UNIVERSITY OF NOVI SAD

FACULTY OF TECHNICAL SCIENCES

Novi Sad
DEPARTMENT OF CIVIL ENGINEERING
AND GEODESY
DEPARTMENT OF ARCHITECTURE AND URBAN
PLANNING
IN COOPERATION WITH
ASSOCIATION OF STRUCTURAL ENGINEERS OF
SERBIA
iNDiS 2015

iNDiS 2015
13 PLANNING, DESIGN,
CONSTRUCTION AND RENEWAL
IN THE CIVIL ENGINEERING
International Scientific Conference

PROCEEDINGS
Novi Sad, Serbia 25 - 27 November 2015

EDITORS
V. Radonjanin, Đ. Lađinović, R. Folić
 UNIVERSITY OF NOVI SAD
FACULTY OF TECHNICAL SCIENCES

DEPARTMENT OF CIVIL ENGINEERING AND

GEODESY

DEPARTMENT OF ARCHITECTURE AND URBAN

PLANNING
IN COOPERATION WITH
ASSOCIATION OF STRUCTURAL
ENGINEERS OF SERBIA

iNDiS 2015
13 PLANNING, DESIGN,
CONSTRUCTION AND RENEWAL
IN THE CIVIL ENGINEERING
International Scientific Conference

PROCEEDINGS
Novi Sad, Serbia 25-27 November 2015

EDITORS
V. Radonjanin, Đ. Lađinović, R. Folić
 Publishing of the Proceedings is supported by Department of Civil Engineering
and Geodesy - Faculty of Technical Sciences - Novi Sad, Ministry of Education,
Science and Technological Development of the Republic of Serbia and with material
support of donators

Editors:
Vlastimir Radonjanin, Ph.D. Civil Engineering
Đorđe Lađinović, Ph.D. Civil Engineering
Emeritus Radomir Folić, Ph.D.Civil Engineering

ISBN 978-86-7892-750-8
CIP - Каталогизација у публикацији
Библиотека Матице српске, Нови Сад

69.05(082)
624(082)

INTERNATIONAL Scientific Conference INDIS (13 ; 2015 ; Novi Sad)

Proceedings [Elektronski izvor] / International Scientific Conference 13 iNDiS 2015
"Planning, Design, Construction and Renewal in the Civil Engineering", Novi Sad, 25-27
November 2015 ; [urednici V. Radonjanin, Đ. Lađinović, R. Folić]. - Novi Sad : Faculty of
Technical Sciences, Department of Civil Engineering and Geodesy, 2015. - 1 elektronski
optički disk (CD-ROM) ; 12 cm

Bibliografija uz svaki rad.

ISBN 978-86-7892-750-8

a) Индустријска градња - Зборници b) Грађевинске конструкције - Зборници

COBISS.SR-ID 301196551

International Scientific Conference iNDiS 2015

Technical organizer of the conference:

Department of Civil Engineering and Geodesy - Faculty of Technical Sciences
Novi Sad

Technical editors of the Proceedings:

Ivan Lukić, Aleksandar Drakulić

Publisher:
Department of Civil Engineering and Geodesy - Faculty of Technical Sciences
Novi Sad

Printing:
Department of Graphic Engineering and Design, Faculty of Technical Sciences
Novi Sad
 iNDiS 2015
This year, Department of Civil Engineering and Geodesy, Faculty of Technical
Sciences - Novi Sad, organizes 13th International Scientific Conference "iNDiS
2015".
The first conference took place in the 1976 with main topic „Industrial construction
of apartments“ as current. In the following years, conference topics were
extended to “Industrialization in civil engineering“, and soon, papers form all
areas of construction have appeared, from urbanism planning and designing
buildings to maintenance and major interventions on engineering structures. It
has caused the expansion of the area covered by this conference and, besides
civil engineers in various fields, urban planners, architects, engineers in other
fields who work in construction, sociologists, economists and others took a part.
The present moment is characterized by, among other things, a crisis in
investment sector, especially in new construction, but, as in the world, more and
more resources must be directed to building management. This requires a
transformation of our activities in construction and adaptation to these trends.
This conference, as well as several previous ones, includes problems of planning,
design, construction and renewal in civil engineering, disaster risk management
and fire safety, which led to an adequate response of foreign and domestic
participants. This wide area includes a wide circle of researchers and engineers,
ie. all professions whose activities are related to architecture, civil engineering,
geodesy and disaster risk management and fire safety in the field of construction.
Members of the International Scientific Committee actively participated in the
preparation of the Conference, as well as in reviewing submitted papers, and
wrote papers published in this Proceeding. These, as well as other papers,
contain a variety of ideas and results of experimental and theoretical research
that became the basis for formulating adequate calculation models of structures
and models used in other areas of civil engineering and environmental protection.
It is expected that, using experience from abroad, adjustment to the legislation
already adopted in Europe will be easier. In addition, it is expected to point out
the main directions of the development of civil engineering in order to meet
modern conditions and needs.
Two Proceedings were published for this conference “iNDiS 2015“, one in the
Serbian and the other in the English language, which allows better
communication and exchange of experiences with colleagues from foreign
countries as well as establishing new and strengthening of existing professional
and collegial relationship.
The editors would like to express sincere gratitude to all authors for the effort
invested in writing papers and for the contribution to this event.

Novi Sad, November 2015 Editors

[i]
Scientific Committee Organizing Committee

Atanacković Jelena, Serbia Vlastimir Radonjanin, Chairman

Balasz Georgy, Hungary Radomir Folić
Banchila Radu, Romania Đorđe Lađinović
Bjegović Dubravka, Croatia Milan Trivunić
Brandl Heinz, Austria Srđan Kolaković
Ćirović Goran, Serbia Darko Reba
Cvetkovska Meri, Macedonia Milena Krklješ
Dan Daniel, Romania Milinko Vasić
Dillinger Thomas, Austria Mirjana Malešev
Dinulović Radivoj, Serbia Tatjana Kočetov Mišulić
Folić Radomir, Serbia
Forde Michael C., England
Gocevski Vlado, Canada
Grdić Zoran, Serbia
Ivanov Yatchko, Bulgaria
Jakimov Todor, Bulgaria
Janković Ksenija, Serbia
Knežević Miloš, Montenegro
Kolaković Srđan, Serbia
Kovačević Dušan, Serbia
Kovler Konstantin, Israel
Krklješ Milena, Serbia
Kukaras Danijel, Serbia
Kurtović-Folić Nađa, Srbija
Lađinović Đorđe, Serbia
Lakušić Stjepan, Croatia
Legat Andraž, Slovenia
Liolios Asterios, Greece
Lučić Duško, Montenegro
Malešev Mirjana, Serbia
Marinković Snežana, Serbia
Marković Zlatko, Serbia
Markovski Goran, Macedonia
Markulak Damir, Croatia
Milašinović Dragan, Serbia
Mirčevska Violeta, Macedonia
Nikolovski Tihomir, Macedonia
Partov Doncho, Bulagria
Pejović Radenko, Montenegro
Petrović Boško, Serbia
Popović Predrag, SAD
Prokić Aleksandar, Srbija
Radonjanin Vlastimir, Srbija
Reba Darko, Srbija
Stanković Milenko, Bosnia&Herzegovina
Stevanović Boško, Serbia
Stoian Valeriu, Romania
Šumarac Dragoslav, Serbia
Tomaževič Miha, Slovenia
Trivunić Milan, Serbia
Veljković Milan, Netherlands
Vuksanović Đorđe, Serbia
Zenunović Damir, Bosnia&Herzegovina
Vasić Milinko, Serbia

[ii]
CONTENTS

EXPERIMENTAL AND THEORETICAL ANALYSIS OF

STRUCTURES
Dragan BOJOVIĆ, Bojan ARANĐELOVIĆ, Ksenija JANKOVIĆ, Marko
STOJANOVIĆ, Lana ANTIĆ
DETERMINING THE FRICTION COEFFICIENT OF CABLE FOR
THE PRESTRESSED ELEMENTS ON PUPIN BRIDGE 2
Ján BUJŇÁK
STUDY ON RECENT STRUCTURAL FAILURES 10
Todor VACEV, Zoran BONIĆ, Milan PETROVIĆ, Verka PROLOVIĆ ,
Nebojša DAVIDOVIĆ
APPLICATION OF FE CONTACT ANALYSIS FOR RETAINING
WALLS MADE OF BETONBLOCK ELEMENTS 20
Jelena DOBRIĆ, Zlatko , Dragan BUĐEVAC, Milan SPREMIĆ, Nenad FRIC
STAINLESS STEEL CROSS-SECTION RESISTANCE ACCORDING
TO CONTINUOUS STRENGTH METHOD 28
Vladimir ŽIVALJEVIĆ, Dušan KOVAČEVIĆ
TESTFRAME - LABORATORY FRAME FOR LOAD TEST OF
STRUCTURAL ELEMENTS 35
Damir ZENUNOVIC, Radomir FOLIC, Mirsad TOPALOVIC, Eldar HUSEJNAGIC
ANALYSIS OF SITE EFFECTS ON BRIDGE STRUCTURE BY
AMBIENT VIBRATION MEASUREMENTS 43
Tatjana KOČETOV MIŠULIĆ, Dragan MANOJLOVIĆ
MODELING OF COMPOSITE TIMBER-CONCRETE SYSTEM
WITH INCLINED CROSS SCREWS 51
Dušan KOVAČEVIĆ, Ranko OKUKA, Igor DŽOLEV
AXISVM® 13 - ADVANCED FEATURES OF FEM SOFTVARE FOR
STRUCTURAL ANALYSIS 60
Dragan D. MILAŠINOVIĆ, Dijana MAJSTOROVIĆ, Radovan VUKOMANOVIĆ,
Nataša MRĐA, Radomir CVIJIĆ
STATIC AND DYNAMIC INELASTIC BUCKLING OF
THINWALLED STRUCTURES USING THE FINITE STRIP
METHOD 67
Branislava NOVAKOVIC
STABILITY OF A BEAM CLAMPED ON ONE END AND
ELASTICALLY RESTRAINED-CLAMPED ON THE OTHER END 74

[iii]
Doncho PARTOV, Vesselin KANTCHEV
COMPARATIVE ANALYSIS BETWEEN (AAEM) METHOD OF
BAŽANT AND INTEGRAL EQUATION OF VOLTERRA IN
INVESTIGATION OF STEEL-CONCRETE BEAM REGARDING
CREEP OF CONCRETE 80
Doncho PARTOV, Chavdar STOYANOV, Milen PETKOV
COMPUTATIONAL ANALYSIS OF THE TIMBER ROOF
CONSTRUCTION OF THE CHURCH ST. DIMITAR IN KUSTENDIL 92
Anka STARČEV ĆURČIN, Đorđe LAĐINOVIĆ, Andrija RAŠETA
Zoran BRUJIĆ, Drago ŽARKOVIĆ
RC PLANE GIRDER STRUT-AND-TIE OPTIMIZATION
ACCORDING TO REINFORCEMENT AMOUNT AND LAYOUT 108
Iliana STOYNOVA, Konstantin KAZAKOV, Radan IVANOV
FEM MODELLING OF FLAT SLAB – COLUMN CONCRETE
CONNECTION SUBJECTED TO STATIC LOADING 116
Mladen ĆOSIĆ, Boris FOLIĆ, Radomir FOLIĆ, Nenad ŠUŠIĆ
PERFORMANCE-BASED SEISMIC EVALUATION OF
SOIL-PILE-BRIDGE PIER INTERACTION USING INDA 124
Meri CVETKOVSKA, Marijana LAZAREVSKA, Ana TROMBEVA-GAVRILOSKA
INFLUENCE OF THE SHAPE OF THE CROSS SECTION AND THE
AXIAL FORCE ON THE FIRE RESISTANCE OF RC COLUMNS 135
Ľuboš ŠNIRC, Monika NAGYOVÁ, Ján RAVINGER
FORMS FOR PRODUCTION OF PRESTRESSED PREFABRICATES 143

CONTEMPORARY CONSTRUCTION MATERIALS

Jelena BIJELJIĆ, Milan PROTIĆ, Saša MARINKOVIĆ, Nenad RISTIĆ .
Zoran GRDIĆ
MECHANICAL PROPERTIES OF STEEL-POLYPROPYLENE
HYBRID FIBER -REINFORCED CONCRETE 152
Vesna BULATOVIĆ, Mirjana MALEŠEV, Miroslava RADEKA,
Vlastimir RADONJANIN, Ivan LUKIĆ
ANALYSIS OF SULPHATE RESISTANCE OF CONCRETE USING
NATRIUM AND MAGNESIUM SULFATE 161
Iva DESPOTOVIĆ, Bojan MILOŠEVIĆ
THE INFLUENCE OF RECYCLED CONCRETE AGGREGATE ON
THE PROPERTIES OF SELF – COMPACTING CONCRETE 172
Dušan GRDIĆ, Nenad RISTIĆ, Gordana TOPLIČIĆ-ĆURČIĆ
EFFECTS OF ADDITION OF FINELY MILLED CATHODE TUBE
GLASS POWDER ON CONCRETE PROPERTIES 179

[iv]
Damir ZENUNOVIĆ, Nesib REŠIDBEGOVIĆ, Snežana MIČEVIĆ, Radomir FOLIĆ,
Eldin HALILČEVIĆ
COMPARATIVE ANALYSIS OF CHLORIDE DIFFUSION
THROUGH CONCRETE COVER OBTAINED BY BDT AND PPT 188
Ksenija JANKOVIĆ, Marko STOJANOVIĆ, Dragan BOJOVIĆ, Ljiljana LONČAR,
Lana ANTIĆ
THE INFLUENCE OF NANO-SILICA ON MECHANICAL
PROPERTIES OF ULTRA HIGH PERFORMANCE CONCRETE 196
Ksenija JANKOVIĆ, Dragan BOJOVIĆ, Marko STOJANOVIĆ, Ljiljana LONČAR,
Lana ANTIĆ
DURABILITY PROPERTIES OF THE SCC CONCRETE WITH
MINE TAILINGS AS A PARTIAL AGGREGATE REPLACEMENT 202
Marija JELČIĆ RUKAVINA, Ana BARIČEVIĆ, Marijana SERDAR,
Martina PEZER, Dubravka BJEGOVIĆ
BEHAVIOR OF REINFORCED CONCRETE WITH RECYCLED
TYRE POLYMER FIBERS AFTER FIRE EXPOSURE 207
Dragica JEVTIĆ, Dimitrije ZAKIĆ, Aleksandar SAVIĆ, Aleksandar RADEVIĆ,
Marina AŠKRABIĆ
INVESTIGATION OF PROPERTIES OF FRESH
SELF-COMPACTING CONCRETE MADE WITH FLY ASH 217
Ivan LUKIĆ, Vlastimir RADONJANIN, Mirjana MALEŠEV, Vesna BULATOVIĆ
INFLUENCE OF MINERAL ADMIXTURES ON WATER
ABSORPTION OF LIGHTWEIGHT AGGREGATE CONCRETE 226
Mirjana MALEŠEV, Vlastimir RADONJANIN, Miroslava RADEKA,
Slobodan ŠUPIĆ, Suzana VUKOSLAVČEVIĆ
THE INFLUENCE OF BIOMASS ASH ON PHYSICAL AND
MECHANICAL PROPERTIES OF CEMENT MORTARS 237
Dragan NIKOLIĆ, Snežana MITROVIĆ, Goran ĆIROVIĆ
AN INVERSE METHOD TO DETERMINE THE MODULUS OF
ELASTICITY OF CONCRETE 246
Irena NIKOLIĆ, Dijana ĐUROVIĆ, Radomir ZEJAK
STRENGTH AND DURABILITY OF ALKALI ACTIVATED
BINDERS BASED ON FLY ASH AND SLAG 254
Miroslava RADEKA, Tiana MILOVIĆ, Mirjana MALEŠEV,
Vlastimir RADONJANIN
EFFECT OF ZEOLITE ON BASIC PHYSICAL PROPERTIES,
MECHANICAL PROPERTIES AND FROST RESISTANCE OF
CEMENT MORTARS 260
Nenad RISTIĆ, Zoran GRDIĆ, Gordana TOPLIČIĆ-ĆURČIĆ, Dušan GRDIĆ
IMPACT RESISTANCE OF CONCRETE MADE WITH ADDITION
MICRO FIBERS AND RECYCLED GRANULATED RUBBER 273

[v]
Ana TROMBEVA-GAVRILOSKA, Meri CVETKOVSKA, Marijana LAZAREVSKA
INFLUENCE OF THE TYPE OF REINFORCEMENT ON THE
BEHAVIOR OF FRP MATERIALS AT INDOOR AND ELEVATED
TEMPERATURES 282

ASSESSMENT, RENEWAL AND MAINTENANCE OF

BUILDINGS
Milica BUBNJEVIĆ, Vladimir ŽIVALJEVIĆ, Vanja VUČINIĆ, Dunja KRTINIĆ,
Mina LJUBISAVLJEVIĆ, Srbislav BABIĆ, Miloš ŠEŠLIJA, Đorđe LAĐINOVIĆ
THE ASSESSMENT OF ROAD PEDESTRIAN BRIDGE ON NEMILA
STREAM IN MELJINE 290
Mina LJUBISAVLJEVIĆ, Dunja KRTINIĆ, Srbislav BABIĆ, Milica BUBNJEVIĆ,
Vladimir ŽIVALJEVIĆ, Vanja VUČINIĆ, Miloš ŠEŠLIJA, Vlastimir RADONJANIN
THE ASSESSMENT AND PROPOSAL OF REPAIR OF STONE
BRIDGE ON THE RIVER SUTORINA IN HERCEG NOVI 298
Predrag L. POPOVIC, James P. DONNELLY
RENOVATION ADDS SPACE AND VALUE TO PARKING GARAGE 306
Predrag L. POPOVIC
EVALUATION AND REPAIR OF PARTIALLY COLLAPSED HIGH
RISE BUILDING UNDER CONSTRUCTION 314
Vlastimir RADONJANIN, Dušan KOVAČEVIĆ, Mirjana MALEŠEV,
Slobodan ŠUPIĆ, Ivan LUKIĆ
TESTING THE INFLUENCE OF DYNAMIC LOADS ON THE
STRUCTURAL ELEMENTS OF PETROVARADIN FORTRESS 322
Dalibor SEKULIĆ
ESTIMATION OF THE STATE OF RC STRUCTURES BY THE
IMPACT-ECHO METHOD USING ADVANCED ANALYSIS 330

DESIGN AND CONSTRUCTION OF BRIDGES AND

ROADS
Doncho PARTOV, Dobromir DINEV
DESIGN APPROACH AND CONSTRUCTION PROCESS OF THE
FIRST LARGE STEEL ORTHOTROPIC BRIDGE IN BULGARIA 339
Slobodan CVETKOVIĆ, Zoja GORONJA
TRACK ARRANGEMENT ON THE RAILWAY BRIDGES WITH
OPEN DECK 349

ASEISMIC DESIGN OF STRUCTURES

Angelos LIOLIOS, Antonia MOROPOULOU, Doncho PARTOV, Boris FOLIC,
Asterios LIOLIOS
CULTURAL HERITAGE RC STRUCTURES STRENGTHENED BY
CABLE ELEMENTS UNDER MULTIPLE EARTHQUAKES 372
[vi]
GEOTECHNICAL PROBLEMS
Slobodan ĆORIĆ, Dragoslav RAKIĆ
FOUNDATION REINFORCEMENT BY MICROPILES 382
Milan ULJAREVIĆ, Slobodan ŠUPIĆ
GEOTECHNICAL FOUNDATION DESIGN OF BRIDGE
"UNDERPASS LUG" 391
Nenad ŠUŠIĆ, Dušan BERISAVLJEVIĆ, Marko PRICA, Ksenija DJOKOVIĆ
DLT-TEST: DETERMINING PILE BEARING CAPACITY USING A
DYNAMIC METHOD 398

MANAGEMENT IN DESIGN METHODS AND

CONSTRUCTION
Jasmina DRAŽIĆ, Aleksandra VUJKOV, Norbert HARMATI
THE MULTI-CRITERIA OPTIMISATION METHOD IN
SELECTING A WALL STRUCTURE BETWEEN TWO FLATS 407
Erika MALEŠEVIĆ
ABC COST ALLOCATION METHOD IN THE CONSTRUCTION
PROCESS 416
Martin TUSCHER, Tomáš HANÁK
MODELLING FLOOD LOSSES TO BUILDINGS: A RESEARCH
DESIGN 426
ARCHITECTURAL AND URBAN PLANNING AND
DESIGN
Borislav Yankov BORISOV
SPATIAL CONCEPT FOR THE INTEGRATION OF TOURISM AND
IMMOVABLE CULTURAL HERITAGE IN THE GENERAL
DEVELOPMENT PLANS IN MUNICIPALITY 436
Borislav Yankov BORISOV
TOURISM AS CRITERION FOR DEFINING THE REGION IN THE
TERRITORIAL DEVELOPMENT ZONING OF BULGARIA 445
Borislav Yankov BORISOV
METHODOLOGICAL ASPECTS OF NORMATIVE REGULATION
OF SPATIAL PLANNING AS A SPECIFIC PART OF THE
PROFESSIONAL FIELD "ARCHITECTURE, CONSTRUCTION
AND GEODESY" IN TECHNICAL SCIENCES 453
Ksenija HIEL, Jovan ĐERIĆ, Dijana BRKLJAČ, Aleksandra MILINKOVIĆ
URBAN BLOCKS OF RESIDENTIAL HIGH-RISE BUILDINGS IN
NOVI SAD 462

[vii]
Yuliya ILIEVA
NEW GEOMETRICAL FORM-FINDING METHOD FOR
CREATING TENSEGRITY MODULES 470
Yuliya ILIEVA
DESIGN OF PLANAR DOUBLE-LAYER TENSEGRITY GRIDS
COMPOSED OF BASIC CUBIC MODULES 478
Yuliya ILIEVA
APPLICATION OF THE “V PLUS V” GEOMETRICAL METHOD
TO FORM-FINDING OF NEW TENSEGRITY MODULES 485
Ljiljana JEVREMOVIC, Branko AJ. TURNSEK, Milanka VASIC,
Marina JORDANOVIC
INCREASING CAPACITY TO REDEVELOP INDUSTRIAL
BROWNFIELDS THROUGH URBAN HERITAGE PROMOTION 492
Milena KRKLJEŠ, Dijana BRKLJAČ, Stefan ŠKORIĆ, Aleksandra MILINKOVIĆ
CHILDREN'S SPATIAL PERCEPTION - DESIGN OF
PLAYGROUNDS 500
Nadja KURTOVIC FOLIC
ON AESTHETICS OF ENGINEERING STRUCTURES 506
Jasmina LUKIĆ, Aleksandar MILOJKOVIĆ, Novica STALETOVIĆ
CONCEPT OF ARCHITECTURAL DESIGN AND CONSTRUCTION
OF RAILWAY PASSENGER TERMINALS 522
Aleksandra MILINKOVIĆ, Ljiljana VUKAJLOV, Dijana BRKLJAČ
INFLUENCE OF ORGANIZATION AND CONTENT OF THE YARD
OF URBAN BLOCK ON THE SOCIALIZATION OF RESIDENTS
CASE STUDY - THE LIMAN BLOCKS IN NOVI SAD 532
Marija STAMENKOVIĆ
THE IMPACT OF GREENERY ON SPATIAL ORGANIZATION OF
PUBLIC BUILDINGS 539
Marina CAREVIĆ
URBANITY AND MIXED USES OF CONTEMPORARY CITIES 548
Stefan ŠKORIĆ, Milena KRKLJEŠ
RECLAIM OF THE CITY'S BUSTLING PUBLIC LIFE IN
CATHOLIC PORT SQUARE 556

SUSTAINABLE DEVELOPMENT AND ENERGY

EFFICIENCY IN CONSTRUCTION
Željko JAKŠIĆ, Norbert HARMATI, Milan TRIVUNIĆ
AN ANALYSIS OF DAMP PRESENCE IN THE SPECIFIC
STRUCTURES OF “DEMIT” FAÇADES 565

[viii]
Konstantin KAZAKOV, Ana YANAKIEVA, Anita HANDRULEVA,
Iliana STOYNOVA, Vladimir MATUSKI
ENERGY EFFICIENCY RENOVATION OF OFFICE-BUILDING IN
SOFIA, BULGARIA - CASE STUDY 573
Željko KOŠKI, Irena IŠTOKA OTKOVIĆ, Hrvoje KRSTIĆ
AIRTIGHTNESS INVESTIGATION OF RESIDENTIAL UNITS
BUILDING ENVELOPE IN CITY OF OSIJEK 580
Milan MARINKOVIĆ, Bojan MATIĆ, Rada STEVANOVIĆ
REVIEW OF USE OF INDUSTRIAL PLASTIC WASTE IN ROAD
CONSTRUCTION 589
Mladen MILANOVIC, Milan GOCIC, Mihailo MITKOVIC, Slavisa KONDIC,
Slavisa TRAJKOVIC
INDICATORS OF SUSTAINABLE GREEN BUILDING 595
Marina PEŠIĆ, Nenad PEŠIĆ, Nikola GAROVNIKOV
ENERGY EFFICIENCY AUDITING OF PUBLIC OBJECTS IN FIVE
MUNICIPALITIES IN MONTENEGRO 603
Igor SVETEL, Marko ЈАRIĆ, Nikola BUDIMIR
TOWARD MODEL INFORMED ENERGY EFFICIENCY DESIGN 611
Norbert HARMATI, Željko JAKŠIĆ, Radomir FOLIĆ, Jasmina DRAŽIĆ
ENERGY PERFORMANCE SIMULATION IN OFFICE BUILDINGS
EQUIPED WITH HEAT PUMP SYSTEM 619

DISASTER RISK MANAGEMENT AND FIRE SAFETY

Senka BAJIĆ, Mirjana LABAN, Jovana SIMIĆ, Vukašin KUKIĆ
FIRE RISK ASSESSMENT FOR SPORTS AND BUSINESS CENTER
BEOČIN 629
Jovana BONDŽIĆ, Nenad MEDIĆ, Tanja NOVAKOVIĆ, Ljiljana POPOVIĆ,
Đorđe ĆOSIĆ
ASPECTS OF PETROL STATION ACCIDENT MODELING 639

Suzana VUKOSLAVČEVIĆ, Mirjana LABAN, Srđan POPOV, Slobodan ŠUPIĆ

CRITICAL ANALYSIS OF THE EVACUATION SIMULATION
SOFTWARE'S APPLICATION 647
Mladen MILANOVIC, Milan GOCIC, Slavisa TRAJKOVIC
SURVEY OF RECOMMENDATIONS FOR DROUGHT
MANAGEMENT 655

[ix]
EUROPEAN STANDARDS IN THE DESIGN AND
CONSTRUCTION OF STRUCTURES
Delyana BOYADZHIEVA
DESIGN OF TIMBER ELEMENTS SUBJECT TO COMPRESSION
COMPARISON BETWEEN EUROCODE 5 AND BUILDING
REGULATIONS OF RUSSIA AND JAPAN 664
Đorđe JOVANOVIĆ, Đorđe LAĐINOVIĆ, Andrija RAŠETA
ON SEISMIC ANALYSIS OF CBF AND EBF STEEL BUILDINGS TO
EN 1998, I: THEORETIC BASIS 674
Đorđe JOVANOVIĆ, Đorđe LAĐINOVIĆ, Andrija RAŠETA
ON SEISMIC ANALYSIS OF CBF AND EBF STEEL BUILDINGS TO
EN 1998, II: CASE STUDY 684
Kiril STOJANOVSKI, Rüdiger HÖFFER, Elena DUMOVA-JOVANOSKA
DESIGN WIND VELOCITY IN THE R. MACEDONIA -
PREPARATION FOR IMPLEMENTATION OF THE EUROCODE 692
Sonja ČEREPNALKOVSKA
CONSTRUCTION PRODUCTS REGULATION (CPR 305/2011),
HARMONIZED STANDARD AND THEIR IMPLEMENTATION ON
A NATIONAL LEVEL 700
Igor DŽOLEV, Meri CVETKOVSKA, Đorđe LAĐINOVIĆ,
Vlastimir RADONJANIN, Andrija RAŠETA
THERMAL ANALYSIS OF CONCRETE MEMBERS SUBJECTED
TO FIRE ACCORDING TO EN 1991-1-2 & EN 1992-1-2 708

DONATORS

[x]
EXPERIMENTAL AND THEORETICAL ANALYSIS
OF STRUCTURES
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Dragan BOJOVIĆ
Bojan ARANĐELOVIĆ2
Ksenija JANKOVIĆ3
Marko STOJANOVIĆ4
Lana ANTIĆ5

DETERMINING THE FRICTION COEFFICIENT OF CABLE FOR

THE PRESTRESSED ELEMENTS ON PUPIN BRIDGE
Abstract: High strength concrete (HSC) application has become common practice in modern Serbian
construction. To overcome the large spans in structures is necessary application of prestressing in HSC.
Dimensioning and design of these constructions requires a large number of input parameters that are
often empirically obtained. For prestressed structures is essential to determine the level of prestressing
force, the coefficient of friction of cables and cable imperfection. These parameters define standards and
are often declared by the manufacturer. The parameters are defined in a wide range and are necessary to
know more accurate values for a cheaper and more effective design. Through this experimental work in
situ, we tried to show in what range the actual friction coefficients.

Кey words: HSC, prestressing force, friction coeficient..

ODREĐIVANJE KOEFICIJENTA TRENJA KABLOVA U

PREDNAPREGNUTIM ELEMENTIMA PUPINOVOG MOSTA
Rezime: Primena Beton visokih čvrstoća (HSC) počela je da bude sve češća pojava u modernom
Srpskom građevinarstvu. Da bi se premostili veliki rasponi u konstrukcijama neophodna je primena
prednaprezanja u betonima visokih čvrstoća. Projektovanje i dimenzionisanje ovakvih konstrukcija
zahteva veliki broj ulaznih parametara koji se najčešće utvrđuju empirijski. Za prednapregnute
konstrukcije osnovno je da se utvrdi nivo prednaprezanja, koeficijenti trenja kablova kao i koeficijent
imperfekcije. Ove parametre definišu najčešće propisi i često sami proizvođači. Parametri su definisani u
širokim opsezima i neophodno je njihovo preciznije poznavanje. Kroz ovaj eksperimentalni rad na
terenu, pokušali smo da pokažemo koji su stvarni opsezi koeficijenta trenja.

Ključne reči: HSC, sila prednaprezanja, koeficijent trenja

1
MSc,Institute IMS, Bulevar vojovde Mišića 43, Belgrade, dragan.bojovic@institutims.rs
2
BScEC,Institute IMS, Bulevar vojovde Mišića 43, Belgrade, bojan.arandjelovic@institutims.rs
3
PhD,Institute IMS, Bulevar vojovde Mišića 43, Belgrade, ksenija.jankovic@institutims.rs
4
MSc,Institute IMS, Bulevar vojovde Mišića 43, Belgrade, marko.stojanovic@institutims.rs
5
MSc, Institute IMS, Bulevar vojovde Mišića 43, Belgrade, lana.antic@institutims.rs

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1. INTRODUCTION
Modern reinforced concrete constructions with significant span cannot be
imagined without prestressing. In order to bridge the large spans as one of the more
economical option is application of prestressing combined with high strength
concrete. The combination of high strength concrete and prestressing is possible to
overcome far greater spans than usual in structures and at the same time is
economically feasible.
The procedure of design prestressed structures established at the beginning of the
application of such systems. Over the years, there were small changes. The basic
premise is that the force in the cable on the active area during the prestressing of the
cable must not exceed the adopted value.
Exceeding adopted value is allowed in cases where the entry prestressing force
controlled modern and very accurate instruments. This case is allowed according to
some international regulations, only when it is unexpectedly high friction at
reinforcing cables over long distances. The maximum force generally calculated in
accordance with equation 1, and the coefficients K1, K2 and K3 are adopted at
national level.
Pmax = A p· p,max (1)
Ap cable cross-section area
 p,max maximal stress which the cable is tensioned = mink 1 · fpk ; k 2 · fp0,1k } or
{k 3·fp0,1k}
Losses that occur during shrinkage cables are not insignificant. The largest share
in the first moments of shrinkage has friction that occurs between cable and pipe into
which is placed the rope. To express this effect has been introduced the coefficient of
friction (μ). In addition to friction and irregularities that occur during the development
serves to reduce the projected force tensioned cables. These irregularities are taken
into account by the coefficient of irregularity (k).
In later structures ages occurs and relaxation of prestressed cables. The
introduction of new types of steel that have good yielding properties to this effect is
minimized.
During the application of the system of prestressing were changing the materials
of all parts of the system. For the calculation of the structure and its performance are
of major importance cables and pipes through which the set cables. The materials
used for these two elements interact, which leads to friction. If this is a much friction
will result in reduce the forces, and vice versa.
In the market there is large number of the manufacturer of the prestressing systems
each of which is specific for something different from the other. However, the
calculation and the conditions that occur when creating structures or some of its parts
are identical for all systems and manufacturers.

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In our construction practice is a common example of the application of new

materials often not enough surveyed. Thus, in the case of prestressed elements
designed route cables are used by steel and plastic pipe as smooth and corrugated.
Plastic pipes are dominant in the market not only because of cost but also because of
the ease of installation in very inaccessible parts of the structure. Taking account of
how and plastics there it is clear that the quality of materials used to make pipes for
prestressing has a major impact on the structure as a whole.
The coefficient of friction is mostly relying on theoretical and laboratory tests. It is
impossible for all types and combinations of materials to examine and determine the
extent to which the coefficients of friction. It should be noted that the coefficient to
irregularities linked to the contractor and his next of experience in such jobs.
In subsequent tension cables prestressing force and the corresponding elongation
of the cable must be checked and measurements must be controlled by the actual
losses due to friction. In addition to these parameters for designers and contractors in
the construction would be of great advantage to be checked and parameters related to
the coefficient of friction and the coefficient of irregularities works on the
prestressing.

2. THEORETICAL AND EMPIRICAL CONSIDERATIONS

Mean value of prestressing force Pm,t(x) at a given point of time t, at distance x (or
measured along the route of the cable) from the active end of the cable is equal to the
maximum force Pmax which tightens the cable on the active end reduced by current
losses and losses depend on the time. All losses are considered in absolute terms.
The value of the initial prestressing force Pm0(x) (at time t = t 0), where the
concrete is exposed directly after tensioning and anchoring cables (with subsequent
tension cables), or after the transfer of prestressing on concrete (at previous tension
cables), we get when the force of the previous tensioning Pmax is reduced by the
current loss P i(x), and must not exceed the following value:
Pm0 (x) = Ap pm0 (x) (2)
where is:
 pm0 (x) stress in the cable immediately after tensioning or transferring force =
min k 7 · fpk ; k 8 ·fp0,1
The prestressing force is usually not constant along the cable due to friction of the
cable on the walls of the channels through which it passes and friction due to changes
in the direction of the cable. In addition, this force overtime and decreases due to
relaxation of steel, shrinkage and creep of concrete.
Accordingly, in one section of the cable have an initial force (Pm0) at the time of
prestressing force at some time "t" (Pm,t) and permanent force, t   , (Pm∞ ), taking
into account the change in force due to the effect of permanent and moving load after
prestressing.

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The current loss of the prestressing force generated during the initial tension
cables and immediately after the procedure tensioning cables, before making
prestressing force to the concrete. These include:
 Losses during tensioning: friction loss in places of bending (in the case of
polygonal wire or cables) and losses due to insertion wedge anchor line
devices.
 before transferring prestressing force to concrete: loss due to relaxation of
cables for prestressing the time that elapses from the tensioning cables to
transferring force and prestressing concrete.
In the case of steam curing concrete, losses due to shrinkage of concrete and
relaxation of prestressing steel should be modified and estimates in an appropriate
manner, with due consideration of direct thermal influences.
 when transferring the prestressing force to concrete: loss due to elastic
deformation of concrete from the force of the pre-tensioned cables on the
concrete element when they are released from the anchor at abutments.
2.1. Loss force due to friction (P (x))
Loss prestressing force occurs in later prestressed concrete elements due to friction
between the cables and protective tubes in the concrete. The size of this loss is a
function of the form of the route of the cable - the effect of curvature and deviations
during assembly of cable route - angular deviation. The values of coefficients that
define force loss are often specified as the process of preparation of the project
selection of different types and shapes of cable route. Since the effect of the curvature
of a predetermined angular deviation is the result of accidental or inevitable
deviations, as there is no possibility that the route of casing the perfect fit.
It should be kept in mind that the maximum value of the force loss due to friction
will be on the other end of the beam if is tensioned at one end. Therefore, friction loss
varies linearly along the span beams and can be interpolated for specific positions if
greater accuracy is needed.
Losses force due to friction P(x) in the subsequent tension of cables can be
assessed by:
P (x) = Pmax (1 – е − ( + kx) ) (3)
where is:
 the sum of the angles of the switch at a distance x (regardless of the
direction or the sign)
 the coefficient of friction between the cable and their pipes
k accidental turn angle of internal cables (per unit length)
x distance along a cable from a point where the force in the cable is equal to
Pmax (force on the active end of the cable during tensioning).

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The coefficient of friction  depends on the surface characteristics of cables and

pipes (holes), and in particular the degree of corrosion of the contact surfaces.
The values for angular deviation k depend on the quality of works: tube-type (or
channel), distances props cable, the degree of vibration when installing concrete and
others. For a value k the stated border 0.005 <k <0.01 per meter (1 / m).
The recommended values for the calculation in Table 1 relate to average
conditions, taking into consideration that the cable meets approximately 50% of the
cross-section tubes.
Table 1. The value of coefficients μ and k
 k
Recommended Recommended
Type of tube Range value Range value
for calculation for calculation
rad-1 rad / m
Corrugated steel
0.18 ÷ 0.26 0.22 (1-10) x 10-3 3 x 10-3

Corrugated
0.10 ÷ 0.14 0.12 (1-10) x 10-3 4 x 10-3
plastic
Concrete 0.34 ÷ 0.62 0.48 (1-10) x 10-3 5 x 10-3

The coefficients k and μ can be found in the documentation of prestressing system.

The values used in the calculation may be increased or decreased within a given
range, depending on the quality of performance, special precautions, control standards
and others. Provided they can justify it.
In prestressed concrete elements there is friction between the cables and the inside
of the pipe during tensioning. Size of friction depends on the type of pipe used and
the type of cable. There are two main mechanisms that produce friction. One is
curvature cable route to achieve the desired route, and the other is unavoidable, and
random differences between the center of cables and pipes.

3. EXPERIMENTAL WORK
The construction of a bridge over the Danube Zemun - Borca used the
prestressing. Prestressing is done to precast beams and structural parts of the central
span of the bridge, which was built cantilever method with two abutments
successively. The Chinese company has its own system of prestressing with all
necessary certification for the European market.
During the design of the bridge there are two possibilities for the use of tubes to
route cables steel and plastic corrugated. Because of the ease of use and cost the
contractor decided to use plastic corrugated pipes. In order to have real data from the

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field the Chinese company has applied for the determination of the coefficient of
friction of cables in I beams length of 26m. Length of applied cables is 27m.
Girders were designed on the class of concrete C40/50 (MB 50) were done
preliminary tests on concrete and on that occasion they met requirements for C45/55
(MB55). Concrete is designed with 420-430kg / m3 of cement CEM II / A (S-L)
42.5R. Aggregate for concrete was from river Morava. To achieve high strength
concrete were used superplasticizers of the last generation that enabled the reduction
of water up to 30%. It was designed concrete consistency class S4 from 160-210mm.

Figure 1. Route of cables N1 and N2

After 28 days of making beams were done prestressing two cables individually.
The first tensioning was cable N1 and then he was released. Then is performed the
second cable N2, and thereafter the same is released. Cables were composed of 7 rope
diameter 15,2mm. Cable route are shown in Figure 1. The diameter plastic pipe is 90
mm. The project envisages that the maximum force in the cables must not exceed
1480kN.
At the active end of the cable press is used for tightening. The force is recorded
with a manometer accuracy class 0.1%. At the end of the passive dynamometer was
used 3000kn capacity and accuracy class 0.1%, which is in regular operation used for
calibrating press for prestressing.
The measurements were made for 80% of the design force for prestressing cables.
For the coefficient of imperfection is taken recommendations from the European
norm. European standards provide for the scope of this coefficient from 0.005 to
0.010.

4. ANALYSIS OF RESULTS AND CONCLUSIONS

After all the measurements that are performed in the field a complete analysis of
the data is made. Coefficients of friction of cables for different values of the
coefficient of imperfection are defined.
The calculation for the adopted values of the coefficient of imperfection from
0,001 to 0,010 calculated values of the coefficient of friction of cables. The results are
shown in Table 2 and Figure 2 shows the test results are mean values of two
measurements on cables N1 and N2.

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Table 2. The ratio coefficient of imperfection and the coefficient of friction of cables
k 0,001 0,002 0,003 0,004 0,005 0,006 0,007 0,008 0,009 0,010

 0,1775 0,1620 0,1490 0,1379 0,1284 0,1201 0,1128 0,1064 0,1006 0,0955

Figure 2. Relationship of coefficients of imperfection and friction cables

Based on results of tests on the building site and processing the test results, it was
concluded the following:
 measurements were carried out showed that one should be careful when
adopting the coefficient of friction imperfections and cables. This conclusion
is a consequence of the results obtained when calculating at trials. Figure 2
clearly shows that the adopted coefficient imperfections of 0,002 and a slightly
lower coefficient of friction of cables may lead to significant differences in the
assessment of the final prestressing force.
 in the case of using recommendations for imperfections coefficient of 0.004
and the coefficient of friction of 0.12 from the accompanying test results to see
if there is a deviation coefficient of friction which is ~ 0.14. This deviation at
the final result in this case is not significant in the final prestressing force.

ACKNOWLEDGMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications" supported by

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the Ministry of Education, Science and Technology, Republic of Serbia. This support
is gratefully acknowledged.

REFERENCES
[1] ETAG 013(Guideline for European Technical Approval of post-tensioning kits
for prestressing of structures), EOTA, 2002.
[2] Sistem za prednaprezanje SPB SUPER, Institut IMS Beograd, 2009.
[3] Nigel R. Hewson, (2003) Prestressed concrete bridges: design and construction
[4] Edward G. Nawy, (2009) Prestressed concrete: a fundamental approach
[5] M.K. Hurst,( 2003) Prestressed concrete design
[6] Benaim R. (2008) The design of prestressed concrete bridges; concepts and
principles

[9]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
Ján BUJŇÁK

STUDY ON RECENT STRUCTURAL FAILURES

Abstract: The study of structural failure events is essential to improving the performance of buildings
and infrastructure and the safety of building occupants. The results of disaster analyses also help assess
the suitability of standards, current practices, and the knowledge in these areas. An example of a
temporary sufficiently designed structure illustrates importance of proper operations. Bad design does
not mean only errors of computation, but an incorrect theories or confidence in inaccurate data. The
bridge structure failure during concrete pouring due to combination of the above reasons proves this
statement. Even an excellently designed and constructed sport hall could not stand on a bad foundation.

Кey words: Structural failure, Buildings, Design process, Construction process, Safety

STUDIJA O NEDAVNIM STRUKTURNIM OTKAZIMA

Rezime: Proučavanje primera strukturnih otkaza je osnovno za poboljšavanje performansi zgrada i

infrastrukture, kao i za bezbednost stanara zgrada. Rezultati analiza katastrofa takodje doprinose proceni
adekvatnosti standarda, trenutne prakse i znanja u ovim oblastima. Primer privremeno dovoljno
projektovane konstrukcije ilustruje značaj ispravnog rada. Loš projekat ne podrazumeva samo greške u
proračunu, već i neispravne teorije ili poverenje u netačne podatke. Otkaz mostovske konstrukcije usled
otpadanja betona, zbog kombinacije gore navedenih razloga, dokazuje ovu tvrdnju.. Čak i odlično
projektovana i izvedena sportska hala nije mogla da stoji na lošim temeljima.

Ključne reči: strukturni otkaz, zgrade, proces projektovanja, proces konstruisanja, bezbednost

Professor, University of Žilina, Faculty of Civil Engineering, 010 26 Žilina, Slovakia, jan.bujnak@fstav.uniza.sk

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1. INTRODUCTION
Structural failures include those failures which occur during the construction of a
structure prior to its exploitation, as well as those which happen after a construction
has been completed and is occupied. In fact, collapses generally have helped to lead
to better understanding of structural performance and contributed much to knowledge
of building design and construction. The causes of major structural failures vary and
usually are due to more than a single factor. Firstly, design errors can result from the
use of incorrect design methods, overlooking critical factors, and lack of attention to
design requirements or load combinations, which may occur during construction.
Further, building inaccuracies include the misunderstanding of design drawings and
specifications. Materials deficiencies, particularly involving earth materials, can also
contribute to failures. Computers allow to look at more options as a solution to a
given problem. At the same time, the increased computational capability presents
further opportunities for errors, both in the development of design and carrying out
the construction. There appears a lack of appreciation of secondary effects such as
corrosion, atmospheric attack, and differential movement. There is a tendency to
build more with less. This is not always accompanied by appropriate analysis of all
the conditions present and the properties of the materials. It might be also noted that
knowledge is still lacking in some specific areas, explicitly wind engineering.
Pressures of time required from the decision to build to occupation can impact the
structural performance of constructions. The use of improved techniques requires
greater team effort and organisation. It is not always clear who is in charge of what
under such construction processes.

2. RISKY WIND ACTIONS ON TEMPORARY STRUCTURES

Temporary spectator area in the form of a rectangle tent for 2 550 participants
consisted of eight tubular vertical columns 300 mm in diameter, carrying axial
compression alone, because their pinned end rotation restrain was negligible [1]. The
compressive forces in the columns were distributed by means of square base plates
500.500 mm to the earth so that bearing stresses remained within acceptable values.
Four threaded round rods 40 mm as anchor bolts had provided the tensile force
resistance of each column footing. Cables composed of small wires  12 mm joined
horizontally the tops of these column masts. The tension ropes were inclined in slope
350 out of the tent contour and anchored to soil at ends. Waterproof textile sheeting
was prepared at the ground level, fixed to the bearing steel rings and after that
uplifted by means of pulleys at the column mast tops in 14 meters height. This roof
covering was suspended between masts with the maximum 3 meters sag in mid-span.
For displacement preventing, textile rectangular prestressed bands 3,6 mm thick and
73 mm large were used also anchored to soil at ends. Vertical round posts 4,2 meters
high in 1,5 meters spacing with their own inclined anchoring had circumscribed the
tent structure border. This supplementary structure parts would allow closing the tent

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spectator area with the vertical screen. But extreme conditions can result in structural
failure.

Figure 1 – Tent structure arrangement

Sudden failure of the tent structure has happened 18 July 2009 in the course of
very poor weather conditions. The weighty steel column masts falling down have
produced serious consequences. Thunderstorm was originated by cumulonimbus
clouds growing vertically instead of horizontally. It was accompanied by heavy rain,
lightings and straight-line winds. Most storm cells expire after relatively short period,
when precipitation causes more downdraft than updraft, causing the energy to
dissipate. Some phases of the consecutive tent structure collapse are illustrated in
Figure 2 together with observers´ pictures showing successive crash stages. It is also
evident that the structure was not enclosed and vertical screens were missing.

Figure 2 – Sequences of the tent structure collapse

According to Beaufort’s scale, the situation can be classified as thunderstorm of

the nine degree with corresponding wind velocity of 21 m/s. For large environment of
this failure area, moreover the wind map specifies the basic wind velocity vb,0 = 24 m/s.
The value of the directional factor cdir can be assumed to be 1,0. The season factor
cseason = 1,0 may be also taken one. Thus, the basic wind velocity was vb,0 = vb,0 =

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24m/s. The terrain is flat with negligible vegetation and without obstacles, as a result
the roughness factor cr(z) = 1,0. The effects of orography may be neglected, because
no slope of the upwind terrain exists and consequently co(z) = 1,0. The mean wind
velocity at a height z above the terrain vm(z)=vb=24 m/s. Reference mean basic
velocity pressure qb=0,5v2=0,5.1,25.242=0,36 kN/m2. The peak velocity pressure
qp(z) at height ze= 11,2 meters includes mean and short-term velocity fluctuations. It
should be determined from relation qp(z) = ce(z).qb. For flat area without obstacles,
the exposure factor ce(z) could be obtained from Figure 4.2 in EN 1991-1-4 [2] as a
function of height above terrain ze and terrain category. For ze= 11,2 meters, it can be
found ce(11,2) = 2,4 and corresponding value of the peak velocity pressure qp(11,2) =
2,4.036 = 0,86 kN /m2. The wind pressure acting on the external surfaces, we , should
be obtained from expression

we= qp(ze)cpe (1)

The pressure coefficients cpe for the external pressure depend on the size of the loaded
area A, which is the area of the structure that produces the wind action in the section
to be calculated. We would apply only cpe,10 because these values should be used for
the design of the overall load bearing structure of the tent area. For circular
cylindrical roofs, the external pressure coefficients cpe = cpe,10 can be determined from
the figure 7.11 of the standard EN 1991-1-4 [2]. Their values cpe are given for zone A,
B and C as function of the ratio of the roof camber f=7,0 m to its span d = 45,0 m. In
the tent structure, the value of this ratio f/d=7,0/45,0 = 0,16. Additionally the values
of the pressure coefficient depend on the ratio of vertical external wall height h to the
tent structure width d, thus h/d = 4,2/45 = 0,09. The reference height was ze = h + f =
4,2 + 7,0 = 11,2 m . Interpolation provides for the zone A pressure cpe = + 0,24, for
the zone B suction action cpe = - 0,87 and for the zone C also suction effect cpe = -
0,40. The design situation considering opened structure should be assessed as
accidental action combination, because the enclosure side walls should resist winding
actions. For this reason, Eurocode EN 1991-1-4 [2] is splitting the internal roof
surface into for zones beginning A to D. The resultant wind pressures acting on the
external as well as internal surfaces are given in Figure 3.

Figure 3 – Wind actions on the external and internal tent surfaces

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The pressure coefficients cpe for the external pressure depend on the size of the
loaded area A, which is the area of the structure that produces the wind action in the
section to be calculated. For circular cylindrical roofs, the external pressure
coefficients cpe = cpe,10 can be determined from the figure 7.11 of the standard EN
1991-1- 4 [2]. Their values cpe are given for zone A, B and C as function of the ratio
of the roof camber f=7,0 meters to its span d = 45,0 meters. Additionally the values
of the pressure coefficient depend on the ratio of vertical external wall height h to the
tent structure width d, thus h/d = 4,2/45 = 0,09. Interpolation provides for the zone A
pressure cpe = + 0,24, for the zone B suction action cpe = - 0,87 and for the zone C also
suction effect cpe = - 0,40. The design situation considering opened structure should
be assessed as accidental action combination, because the enclosure side walls should
resist winding actions. For this reason, Eurocode EN 1991-1- 4 [2] is splitting the
internal roof surface into for zones beginning A to D. The resultant wind pressures
acting on the external as well as internal surfaces are given in Figure 3.
The wind force Fw on a structure or a structural element may be determined by
vectorial summation of the forces calculated from the external pressure we(ze) at
reference height ze and internal one wi acting on the reference area Aref of the
individual surfaces

Fw = cscd.we(ze).Aref (2)

The structural factor cscd takes into account the effect of wind actions from the
non-simultaneous occurrence of peak wind pressures on the surface by size factor cs
together with the effect of the vibrations of the structure due to turbulence by
dynamic factor cd. For buildings with a height less than 15 meters the value of cscd
may be taken as 1. The wind force Fw acting on the roof part between adjacent
column mats, 15 meters spaced, produced by only the external pressures, i.e. for the
enclosed tent structure would be Fwe,standard = γf .15.Σ we.di = 1,3.15.(0,21.5,6 –
0,76.22,4 – 0,35.17) = - 425,06 kN. The forces produced by the external and internal
pressures would be
Fw,standard = 1,3.15.(0,21.5,6 – 0,76.22,4 – 0,35.17) - 1,3.15.(1,22.4,5 + 0,79.13,5 +
0,35.9,0 + 0,79.13,5 + 1,22.4,5) = - 1 116,53 kN, i.e. practically 125 % superior.
While the tent structure is opened, its resistance to wind may be two times
underestimated, which can provide explanation for its collapse. Thus some failures
are not the result of poor design, but the consequence of unforeseen events that create
uncommon loads on structures. The above results are close to the original design [3].

3. FAULTY BRIDGE BACKUP SCAFFOLD ASSIGNMENT

Approximately 50% of all structural failures are due to bad design. The faulty
projects can be caused by design errors such as mistake to account for load,
specifying incorrect conception, or not considering important factors and stresses.
Two similar parallel continuous girder highway prestressed concrete bridges 176
meters long have two equal end spans of 27,9 meters length and three intermediary

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

spans 39,9 meters [4]. The left superstructure comprising the third supplementary
lane is 17.5 meters wide with three pretensioned beams from C45/55 concrete class
with the structural depth 2,80 meters. The right bridge with only two lanes has width
reduced at 13,65 meters. The center-to-center distance between adjacent girders in the
cross-section was 5,6 meters. Concrete deck slab 200 mm thick from C30/37 concrete
class attached to the girders can provide composite action. Cast in place cross-girders
after hardening should interconnect adjacent spans and provide longitudinal
continuous bridge behaviour. Entirely 28 multistraight prestressing tendons, LS
15,5/1800 MPa were situated in girder flanges. Supplementary four cables in deck
slab were required for continuity reasons. The bridge was designed to be constructed
using the formwork for concrete pouring supported by a scaffold suitable for the tasks
in five sequences of construction processe.

Figure 4 – Bridget structure arrangement

During the afternoon of Friday 2 November 2012, the bridge, part of the highway
under construction suddenly collapsed, trapping the personnel on the construction
project. Four of those working for construction company found dead in the downfall.
Eleven workers employed by a subcontractor were injured.

Figure 5 – Bridget cross-section and scaffold arrangement

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Scaffold towers were built-up sections connected together by means of imperfect

battens and double lacing. Their vertical compression members were about 19 meters
long and had to carry large compressive loads. The purpose of this arrangement was
to distribute the material far away from tower centroid axes for providing sufficient
compressive load carrying capacity and also offering easy assemblage of supports at
the building site. By furnishing intermediate backings to compression member, the
unsupported length could be theoretically reduced. However the buckling strength of
built-up columns is always smaller than that of solid column having the same
slenderness ratio and the same area due to shearing forces producing deformations in
the lattice. Particularly in columns with battens, it is assumed that the shear should be
carried by bending of the longitudinal elements as main segments and of batten
plates. Unfortunately improper timber plates and round tension coupling rods were
not sufficiently rigid battens, able to make all of the scaffold components as a unit.
The buckling and sudden bending of solid web rolled I 500 longitudinal main
segments happened prior to developing the full material strength, because the lattice
was unable to assure integral action built-up towers.

Figure 6 – Deflected shape of latticed tower as a whole

4. HALL FOUNDATION FAILURE

Buildings, like all structures, are designed to support certain loads without
deforming excessively. Standardized metal hall structures are widely used in
industrial, commercial, agricultural applications and community facilities, because
they can provide attractive appearance, fast construction, low maintenance, easy
extension, and lower long-term cost.

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The type of barrel vault was applied to the construction of an ice hockey stadium
with the walls and roof combined together [5]. The form of roof was a single-
curvature cylinder, with the structure consisting of steel roof panels arranged on a
cylindrical surface. The transverse span between the supports was 37,0 meters. The
building had 63 meters length and 10,2 meters rise. As the height-to-width ratio varies
about 1/6,18, the primary structural response had to be a beam action. The barrel vault
was sufficient long to be design as parallel arches with curvilinear cross-sections with
extreme compressive stresses near the quarter of span. For erection, the structure was
divided into individual strip blocks, 5,0 meters long and 1,25 meter wide cold-formed
from low alloy steel sheet 1,5 mm thick, corrugated in the wave shape 225 mm high.
With more work being done on the ground, the amount of assembling work at high
elevation could be reduced. In order to fulfil the functional requirements, the load-
resisting behaviour of the structure as a whole and also its relation to the supporting
structure should be taken into consideration.

Figure 7 – Shape of barrel vault building

This vault had been supported continuously along its longitudinal edges on
foundation blocks. The structure finalized already 7 December 2011, as a good recent
example, collapsed on 9 February 2013 early in the morning. Structure was correctly
designed for snow and wind effects. The investigations have proved that the amount
of snow load has respected the location of the structure as well as the slope of the
roof, specified in the building codes. However even an excellently designed and
constructed structure cannot stand on a bad foundation. Though it carries sufficiently
its loads, the earth beneath it may not.

Figure 8 – Mode of vault structure collapse

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

With regard to vertical loads, foundations can receive almost concentrated forces
from the structure and transfer these effects to the soil underneath the foundation,
distributing the load as a stress over a certain area. Part of the soil structure
interaction is then the condition that the stress must not give rise to a deformation of
the soil in excess of what the superstructure can tolerate. But, an inclined load can
have a significant reducing effect on the bearing capacity of a foundation. Firstly by
the inclination factor and then also because the resultant to the load on most occasions
acts off center, causing increased edge stress on one side and a decreased stress value
on the opposing side. Generally, the resultant must fall within the middle third of the
foundation. A large edge stress can be the starting point of a failure by tilting, which
is an indication of excessive edge stress. The inclined load has also a horizontal
component and the calculation of a structure base stability must check that the safety
against sliding is sufficient.
Failure was caused also by poor soil conditions. Long and poor installation by
succesivelly altering bankruptcying companies during long two years, including
winter times produced important degradation of subsoil. Compressibility of the soil
mostly is the result of a change of pore volume. In partially saturated soils, settlement
is evidently rapid, because gas is readily compress when subjected to an increase of
pressure. The foundations sank excessively into soft subsoil.
Thus the collapse resulted from the others numerous shortcomings. The
displacements due to bad foundations have altered the stress distribution significantly.
The foundation displacements transformed originally two-hinged arch as a curved
structural member spanning between bases in curved beams with maximum mid-span
stresses in its crown. The failure shape in Figure 7 illustrates this behavior and points
of the destruction.

5. CONCLUDING REMARKS
Three case studies of structure failure due to accidental actions were presented in
the paper. Their consequences are influenced by properties of the structure, location
and further conditions. Generally, the causes of structural failures vary, and usually,
but not always, are due to more than a single factor. Design errors can result from the
use of inappropriate design methods, overlooking critical factors, and lack of attention
to design requirements. Construction errors include the misinterpretation of design
drawings and poor workmanship in placing, connecting and protecting materials and
members. There is a tendency to build to higher and wider limits and to exploit high
strengths. This is not always accompanied by appropriate analysis and understanding
of all the conditions present and the properties of the materials. There should always
be a design review, irrespective of the identity, qualifications and experience of the
designer. Even the most competent designers can make mistakes. The consequences
of those errors can be avoided only if another suitably qualified and experienced
person checks their work.

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Professional education today exhibits a strong emphasis on theoretical and

fundamental understanding of the sciences. This is at the expense of gaining practical
knowledge

ACKNOWLEDGMENT
The paper presents results of the research activities supported by the Slovak Grant
Agency; grant No. 1/0583/14.

REFERENCES
[1] Bujňák, Ján. Forensic investigation report of the temporary spectator area in the
form of a rectangle tent collapse. University of Žilina 2013.
[2] EN 1991-1-4, Eurocode 1: Actions on structures - General actions - Part 1-4:
Wind actions. 2005
[3] Auszug aus den Richtlinien fur den Bau und Betrieb Fliegender Bauten, Fassung
April 1977 bzw. Oktober 1989. ZELTE, Stadt Koln, Der Oberstadtdirektor
Bauaufsichtsamt, Anlage zu Pruftbuch 95/99.
[4] Bujňák, Ján. Forensic investigation report of the highway bridge scaffold failure.
University of Žilina 2013.
[5] Bujňák, Ján. Forensic investigation report on the failure of the prefabricated
steel hall of the ice hockey stadium. University of Žilina 2013

[19]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Todor VACEV
Zoran BONIĆ2
Milan PETROVIĆ3
Verka PROLOVIĆ4
Nebojša DAVIDOVIĆ5

APPLICATION OF FE CONTACT ANALYSIS FOR RETAINING

WALLS MADE OF BETONBLOCK ELEMENTS
Abstract: The topic of this paper is analysis of the stability of retaining walls made of standard
betonblock elements, easily assembled like "Lego" cubes, without binding. Aim of this research was to
determine bearing performances of the system subjected to active soil pressure, proportional to the wall
height. For the analysis a finite element model was built using solid elements. All adjoining surfaces of
the elements were "coated" with special contact elements, and full contact analysis was done, including
the friction effects, using FEA software ANSYS 14.5. The same structure was built in situ, and
horizontal displacements were measured and compared with FEA data with good agreement.

Кey words: concrete block, retaining wall, FE analysis, contact.

PRIMENA KONTAKTNE MKE ANALIZE KOD POTPORNIH

ZIDOVA OD BETONBLOK ELEMENATA
Rezime: Tema rada je analiza stabilnosti potpornih zidova izrađenih od standardnih betonblock
elemenata, koji se lako sklapaju, poput "Lego" kocki, bez veziva. Cilj istraživanja je bio da se odredi
nosivost sistema. Zid je bio izložen aktivnom pritisku tla, proporcionalnom visini zida. U cilju analize
izrađen je model od zapreminskih konačnih elemenata. Sve dodirne površine elemenata su "obložene"
specijalnim kontaktnim elementima, i obavljena je puna kontaktna analiza, uključujući i efekte trenja, uz
primenu MKE softvera ANSYS 14.5. Ista konstrukcija je realizovana i na terenu, i izmerena su
horizontalna pomeranja zida i upoređena sa MKE podacima, uz vrlo dobro slaganje.

Ključne reči: betonski blok, potporni zid, MKE analiza, kontakt.

1
Assistant professor, Civil Eng. and Architectural Faculty Niš, A. Medvedeva 14, Niš, Serbia,
todor.vacev@gaf.ni.ac.rs
2
Assistant professor, Civil Eng. and Architectural Faculty, A. Medvedeva 14, Niš, Serbia
3
Master Eng., Ph.D. student, Civil Eng. and Architectural Faculty, A. Medvedeva 14, Niš, Serbia
4
Full professor, Civil Eng. and Architectural Faculty, A. Medvedeva 14, Niš, Serbia
5
Assistant professor, Civil Eng. and Architectural Faculty, A. Medvedeva 14, Niš, Serbia

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. RETAINING STRUCTURES
Retaining structures are permanent or temporary, solid or parsed structures whose
main task is to support or prevent the collapse of the steep terrain cuts as well as
material slopes in the embankment. They allow a sudden change of ground level in
order to obtain available space for performing foundation pits, providing side cuts,
road embankments, bridge abutments, dock walls, navigation locks, repositories, etc.
For this purpose, in addition to conventional rigid walls (stone, concrete and
reinforced concrete), and flexible retaining structures (sheet piles, diaphragms,
geotechnical anchors, pile walls), nowadays are increasingly used modern structures
of reinforced earth, gabions, and precast concrete and reinforced concrete elements.

2. RETAINING WALLS OF PRECAST BETONBLOCK ELEMENTS

Landslides and mudslides are frequent along the roads after the winter months,
when there is snow thawing and soil unfreezing. This results in increase in the content
of water in the soil and consequently increase in the soil weight, reducing the
cohesion and the formation of the sliding surfaces. The most common cause of these
phenomena is inadequate drainage of surface water above and below the road. The
result of these processes is backfilling or abruption of road segments or disabling its
basic function.
In these conditions, it is very important to choose such measures of rehabilitation
that would in a fast, efficient and reliable manner restore the road to its functional
state at a low cost. Retaining structures that best meet the above requirements are
retaining walls of reinforced earth, gabions and precast elements.
Retaining walls of precast elements represent a cheap, simple and visually
attractive solution. They are based on the principle of dry construction, usually
without the use of fresh concrete and the construction of the footing of the retaining
wall. This significantly reduces the time and cost of construction, allowing easy
erection in all weather conditions, which are important factors in selecting the type of
the retaining structures.
The basic unit of the retaining walls of precast betonblcok elements is a concrete
block with typical dimensions LxBxH=150x60x60cm (Fig. 1). Elements are produced
with pyramidal studs on the top and recesses in the base of the blocks, so that
elements can be easily assembled into retaining walls, separation walls, fences, etc.
like "Lego" cubes, totally without binding. Concrete blocks are produced by "PUT
INŽENJERING" company from Niš, Serbia [1], and they are already used on many
locations.

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3. FINITE ELEMENT ANALYSIS

The main goal of this research was to determine bearing performances of the
concrete block system, used as retaining wall. The structure is subjected to active soil
pressure, calculated according to the Rankine theory.

a) b)
Fig. 1 a) Concrete block element (measures in cm); b) application as separation walls

The analysis of the structure was done using finite element analysis (FEA) and
software ANSYS 14.5 [2]. FE model was built using solid tetrahedral elements (Fig.
2). All adjoining surfaces of the blocks were additionally "coated" with special
contact elements, and full contact analysis was performed, including friction effects.

a) b)
Fig. 2 – FE model of a concrete block element
a) Block with soil pressure load; b) detail - notice higher mesh density on surfaces in contact

Real betonblocks are produced with tolerance between the studs and the recesses
on the block. This tolerance in horizontal direction is designed to be 5 mm, and
measurements taken from samples at production stock showed average tolerance of

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approx. 6 mm. However, the FE model was built with no gaps at the stud-recess
contact, i.e., it was assumed that the elements were produced without horizontal
tolerance. Reason for this modification is saving the processing time needed for the
analysis. Namely, existence of gaps would require significant number of analyzing
steps in order to achieve contact between adjoining bodies, i.e., upper body should
"travel" along lower body for 5 mm to come into contact. Regarding vertical
tolerances, they were maintained as in real samples, i.e., 5 mm (Fig. 3).

5 mm tolerance

Detail

No tolerance

a) b)
Fig. 3 – FE model of a concrete block element
a) Block assembly H=2x60=120 cm; b) stud and recess assembly - adopted tolerances

Walls of different heights, length, and number of blocks were analyzed (see Table
1). In the analysis, several parameters were especially observed: horizontal
displacement of the wall top, contact stresses at adjoining surfaces of the elements,
contact pressure on the concrete base, and separation of the bottom block from the
concrete base (lifting). In all analyses, blocks were laid on a concrete slab 20 cm
thick, fixed in all directions. If required, different material, e.g. soil, could be used in
analysis. Boundary conditions on the blocks are totally omitted, i.e., blocks are self-
supported via contact surfaces, which highly reflects the assembly concept of the
system.
Graphic representation of the analysis results is given for Model 4 (Fig. 4, 5)
consisted of 7 layers of blocks with total dimensions LxBxH=3x0.6x4.2 m.

Table 1 - Characteristic FEA results for different models

Model Wall Max. horizontal Max. contact Max. contact Max. Separation
dimensions displacement total stress in pressure on contact from
LxBxH [m] [mm] blocks [MPa] concrete base tension concrete
[MPa] [MPa] base [mm]
2 1.5x0.6x3 9.10 10.10 1.51 -0.43 1.20
3 3x0.6x3 2.66 2.38 1.52 -0.44 0.32
7 15x0.6x3 2.71 1.63 1.45 -0.48 0.28
4 3x0.6x4.2 52.39 16.4 4.48 -1.02 4.34

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a) b)
Fig. 4. Model 4. a) FE mesh and soil pressure;
b) horizontal displacements x10 (max. 52.4mm)

a) b)
Fig. 5. Model 4. a) contact pressure of the bottom block on the concrete
base (max. value 4.48MPa);
b) Contact total stress at stud surfaces - detail (max. value 16.4 MPa)

4. TESTING OF THE RETAINING WALL OF PRECAST BETONBLOCK

ELEMENTS
Aim of the test was to reproduce the real situation in situ in the case of gravity
retaining wall when the space behind the wall is filled with coarse material, which is a
common request in the case of retaining walls along the roads. Model of the structure
is made on a concrete base, in situ, in the scale 1:1, with length of 15.0 m and height

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

of 3.0 m, or 5 rows of blocks. The space behind the wall is filled with coarse crushed
aggregate fraction of 0/32 mm. Material was embankmented to a height of 0.90 m,
when the first measurement of horizontal displacements of the points on the wall was
made, according to Fig. 6. Horizontal displacements of characteristic points of the
wall are registered by surveying instruments - total station SOKKIA Set 630R [1].

Fig. 6 – Measurement points on the experimental model

After that filling the space behind the wall is continued to the full height of the
wall, i.e., 2.40 m, when new horizontal displacements of the same points on the wall
are registered. Since the registered displacements of the wall were small, another row
of betonblock elements was placed, and the height of the wall of 3.0 m was reached
(Fig. 6, at right). The space behind the wall was filled with material to the height of
the wall again, and new horizontal displacements are measured again. Summary of
the measured displacements of the characteristic points of the wall is shown in Table
2, and some phases of the experiment are presented in Fig. 7.

Fig. 7 – Some phases of the experiment - testing of the retaining wall to static influence

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Table 2. Registered horizontal displacement of the wall

Measurement Measurement Horizontal
Vertical
point mark point height [m] displacements [mm]
1 0.30 5.0
2 0.90 6.5
I 3 1.50 7.0
4 2.10 12.5
5 2.70 16.5
1 0.30 1.0
2 0.90 4.5
II 3 1.50 9.0
4 2.10 11.5
5 2.70 14.0
1 0.30 7.0
2 0.90 10.0
III 3 1.50 11.5
4 2.10 14.0
5 2.70 18.0

5. DISCUSSION
FE analysis of retaining wall models with different dimensions revealed that
horizontal displacements of the top of the wall depend of two parameters: wall height
and wall length. Namely, the horizontal displacements increase with the increase of
the wall height - from cca. 2.7 mm for 3.0 m high wall (5 block layers), to even 52.4
mm for the 4.2 m high wall (7 block layers). Reason for this is obvious - increase of
the active overturning moment from the soil pressure. On the other hand, the
increasing of the wall length decreases the horizontal displacements. Explanation for
this could be found in the longitudinal bonding of the blocks, which further
strengthens the wall. All this should be considered at design of such structures.
Stability of the structure to overturning is determined using classical approach by
comparing of active and reactive moments, with some safety factor (usually 1.5-2).
Using of the contact FE analysis employs nonlinearities involving large deformations
and changing of contact status. Such approach gives much more real representation of
the behaviour of the structure. The main task here should be to determine adequate
criteria for stability. One of the indicative parameters is tracking of the separation of
the wall bottom from the concrete base, or any upper element from the downlaying
one. In the cases analyzed above those "lifting" values were from 0.3 mm to 4.3 mm,
depending of the height and length of the wall. The allowed separation values should
be proposed and limited, and they should be part of future investigations. Since FEA,

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

and especially contact analysis, are nowadays far from being part of the building
codes (Eurocode primarily), investigations of this type could give helpful guidelines.
Another benefit of the contact analysis is obtaining the data about the pressure of
the structure on the concrete base, also presented in Table 1. Stress concentrations on
the studs can be also detected.
However, contact FEA falls into highly nonlinear and the most demanding
numerical problems. Careful consideration of every case is necessary. Like every
numerical solution, this one too is approximate. Accuracy of the solution can be
improved by varying of numerous contact parameters given in the software. The
analyses presented here also revealed difficulties in obtaining the correct solution.
Namely, the parasite tension stresses given in the Table 1 are consequence of
applying of the so called "weak springs" used to stabilize the numerical solution.
Minimizing of the stiffness values of those springs gives better results, but potentially
leads to divergence [3]. Balance between those conditions requires careful, sometimes
tedious work. However, gains of applying such analysis can be of a more general
significance, since most of the structural problems involve some kind of contact.
Comparison of the FEA and test results are possible in this case only regarding the
horizontal displacements of the wall. Test data show displacements near the wall top
of 14-18 mm. The most similar FE model 7 gave displacement value of 2.71 mm.
This seemingly high disagreement arises largely from the tolerance movements
between the block layers in situ, which was eliminated in the FEA. Knowing this, one
may notice that two methods have very good agreement.

6. CONCLUSION
The retaining wall system and analysis results presented in this paper, confirm two
facts about it: first, simplicity of erection and use, and second, reliability in
determination of its behaviour using contact FEA. Those qualities joined together
offer further potential applications to this system, with guaranteed performance.

REFERENCES
[1] "PUT INŽENJERING" Company, Niš, Serbia, Commercial material
[2] ANSYS 14.5, (2012): Software Manual, ANSYS Inc.
[3] Metrisin, J.T., (2008): International ANSYS Conference Guidelines for
Obtaining Contact Convergence, ANSYS Inc.
[4] http://betonblock.com/

[27]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Jelena DOBRIĆ
Zlatko MARKOVIĆ2
Dragan BUĐEVAC3
Milan SPREMIĆ4
Nenad FRIC5

STAINLESS STEEL CROSS-SECTION RESISTANCE ACCORDING

TO CONTINUOUS STRENGTH METHOD
Abstract: Continuous strength method is a contemporary approach to calculation of resistance of
stainless steel cross-sections which has been recently developed at the Imperial College of London. The
basis of the method is the continuous relation between the slenderness and strain capacity of a cross-
section, nonlinear relation between the stress and strain and the strengthening effects of cold forming. In
the paper are presented the fundamental rules for calculation of cross-section resistance according to
continuous strength method; the comparative analysis of design resistance of the compressed cross-
section was conducted through a numerical example according to this method and EN 1993-1-4.

Кey words: Stainless steel, Continuous strength method, Nonlinearity, Buckling, Resistance

NOSIVOST POPREČNIH PRESEKA ELEMENATA OD NERĐAJUĆEG

ČELIKA PREMA METODI KONTINUALNE ČVRSTOĆE
Rezime: Metoda kontinulane čvrstoće predstavlja savremen pristup u proračunu nosivosti poprečnih
preseka elemenata od nerđajućeg čelika koji je poslednjih godina razvijen na Imperijal Koledžu u
Londonu. Osnovu metode predstavljaju kontinualna veza između vitkosti i kapaciteta deformacije
poprečnog preseka, nelinearna veza između napona i dilatacija i efekati ojačanja materijala usled hladne
deformacije. U ovom radu su prikazana osnovna pravila proračuna nosivosti preseka prema Metodi
kontinualne čvrstoće i, kroz numerički primer, izvršena komparativna analiza proračunske nosivosti
pritisnutog preseka prema ovoj metodi i EN 1993-1-4.

Ključne reči: Nerđajući čelik, metoda kontinualne čvrstoće, nelinearnost, izbočavanje, nosivost.

1
Ph.D, B.C.Eng,assistant professor,Faculty of Civil Engineering University of Belgrade,jelena@imk.grf.bg.ac.rs
2
Ph.D, B.C.Eng,full professor,Faculty of Civil Engineering University of Belgrade,zlatko@grf.bg.ac.rs
3
Ph.D, B.C.Eng,full professor,Faculty of Civil Engineering University of Belgrade,budjevac@grf.bg.ac.rs
4
Ph.D, B.C.Eng,assistant professor,Faculty of Civil Engineering University of Belgrade,spremic@imk.grf.bg.ac.rs
5
Ph.D, B.C.Eng,assistant professor,Faculty of Civil Engineering University of Belgrade,fric@imk.grf.bg.ac.rs

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1. INTRODUCTION
Stainless steel is a generic term for a wide range of steel alloys, of varying kind
and quality, whose resistance to corrosion is achieved with a content of no less than
10,5% of chromium and no more than 1,2% of carbon. Its usage in civil engineering
is synonymous with luxurious and attractive architecture, while its usage in
conventional structures is still limited. The main reason is, above all, high cost of
stainless steel in comparison with the traditional application of carbon steel. The most
used materials in construction industry are austenitic and duplex steel. By observing
the market demands and by continuously improving the production process in the
previous decade the metallurgy industry initiated production of new, depleted alloys
of stainless steels, ferrous and low-alloy duplex steels with low content of nickel, in
this way simultaneously achieving the competitive cost and primary properties of
stainless steel.
The basic specific properties of austenitic stainless steels are material nonlinearity,
anisotropy and asymmetry, ductility and considerable strain hardening due to cold-
formation [1]. The stress-strain curve is prominently nonlinear, there is not clearly
yield point and plasticity plateau and has a low value of stress on the proportionality
limit and it indicates gradual yielding of material. The absence of a sharply defined
yield point necessitates the definition of an equivalent yield point, wherefore is
adopted the value of stress at 0,2% plastic strain (0,2% proof stress). From the point
of view of the cross-section resistance, the important characteristic of stainless steel is
reflected in the improvement of mechanical properties due to cold-forming: rolling or
press braking. This fact is very important if one considers that stainless steel is mostly
used in civil engineering in the shape of cold-formed products. The response to
plastic strain is the material strengthening effect which significantly increases the
yield point and, slightly less, the tensile strength followed with a reduction in ductility
and the formation of residual stresses.
The elastic buckling theory can, in case of elastic-plastic materials, be used only in
the initial domain of elasticity. In case of nonlinear materials, such as the stainless
steel, in the stress domain above the proportionality limit, the stiffness during loading
is proportional to the tangent modulus, and at unloading it is proportional to the
modulus of elasticity. For that reason in case of calculation of cross-section resistance
where buckling occurs in the inelastic (nonlinear) stress domain above the
proportionality limit, a well known expression for the elastic buckling stress cannot
be implemented. In addition, implementation of a design concept which is based on
the perfectly elastic-plastic material model such as carbon steel leads to conservative
results. Considering the uncompetitive position of stainless steel in construction
industry, correct analysis and usage of all of its characteristics is of essential
importance for proposing the design recommendations.

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2. THE CONTINUOUS STRENGTH METHOD

Concept of cross-section classification (or the effective width concept) is a method
which allows defining the resistance of a cross-section in function of the yield point
as the maximum value of stress which can be reached in the cross-section. This
method ignores the significant strain hardening of stainless steels and may produce
conservative results, especially for stocky cross-sections whose resistance is
determined by the higher values of stress in comparison with the yield point.
The Continuous Strength Method (CSM) [2],[3] represents a contemporary
method for design of cross-sectional resistance, which was created as a result of
extensive experimental and analytical studies for the stainless steel members loaded
by compression and bending. The nature of the stress-strain relationship for stainless
steel, and absence of a clear yield point, has as a consequence that the maximum
value of failure stress is not determined by the yield stress start. According to this
method, the stress at which a cross-section buckles (local buckling stress) represents
the only physical limit in the continuous improvement of mechanical properties of a
material which follows the increase of the strain. Such approach permits a more
precise analysis of local buckling effects in calculation of stainless steel cross-section
resistance in comparison with the traditional concept of effective width.
Elastic buckling stress can be determined by applying available numerical
methods CUFSM [4]. Alternatively, according to the recommendations given in EN
1993-1-4 [5], the smallest value of critical stress of an individual part of cross-section
can be assumed as the elastic buckling stress which results in the following equation
for cross-section slenderness:
f 0,2 b/t
p   (1)
 cr, p,min 28,4 kσ
where:
ζcr,p,min is the smallest value of critical stress of an individual part of cross-section,
b is the width of the considered part of cross-section,
t is the corresponding wall thickness of the cross-section part,
ε = [(235/f0,2)(E/210000)]0,5,
k is the buckling coefficient which depends on the support conditions and
distribution of stress.
Deformation capacity of the cross-section is expressed in a normalized form, and
for the stocky cross-sections it is the relation of the strain corresponding to the value
of ultimate load at which buckling occurs, εcsm, and the elastic part of strain at 0,2%
proof stress, ε0,2,el.
By implementing linear regression method in the analysis of experimental data
obtained by testing compressed stub columns it was shown that the area in which the

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relations of the ultimate load and the section yield load, Nu/Af0,2 highter than unity, is
determined by the limit value of the cross-section slenderness:
 p  0,68 (2)
This value determines the limit between the slender cross-sections that fail due to
local buckling in the elastic domain of stress and the non-slender cross-sections where
local buckling occurs in the inelastic domain, after reaching the yield point. A similar
value is observed in equivalent analyses of the structural elements made of carbon
steel and aluminum alloys.
700
fu
600

500
Stress (MPa)

Esh
400 σlb

300 fcsm
f0,2
Continuous Strength Method material model
200
Average Stub Column test

0,16εu
100 Average Longitudinal Tension test
ε0,2
εlb

0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Strain (%)
Figure 1 – Material model according to Continuous Strength Method [3]
In case of stocky cross-sections where the value of the ultimate load Nu exceeds
the value of the cross-section yield load (N0,2= Af0,2), the relation of the end shortening
at the ultimate load δu and the length of the stub column L, is defined as strain
occurring at ―failure‖ of the cross-section εlb due to inelastic local buckling. Strain εcsm
is determined by subtracting the plastic part of the strain at the 0,2% proof stress from
the total value of the local buckling strain εlb:
 csm   lb  0,002   u / L  0,002; N u  N0,2;  p  0,68 (3)
All the available results of experimental research of stub columns and bending
beams, combined with the equivalent results of carbon steels members were analyzed
in order to generate the design curve which defines the relationship between the
normalized value of deformation capacity εcsm/ε0,2,el and slenderness of the cross-
section  p . By using the regression analysis and setting the condition that the design
curve must pass through the identification limit between the slender and non-slender
(stocky) cross-sections, i.e. through the point (0,68;1,0) the following equation was
obtained:
 csm 0,25
 (4)
 0,2,el  p3,6

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Where the value of the strain ε0,2 is determined by the expression:

f 0,2
 0,2,el  (5)
E
Two upper bounds regarding the deformation capacity of the cross-sections were
adopted, resulting from the conditions of required ductility of the material given in
EN 1993-1-1[6] and of the adopted stress-strain material model:
 csm  0,1 u 
 min15;  (6)
 0,2,el   0,2
 
The first versions of the Continuous Strength Method were based on the Ramberg-
Osgood material model [7] which resulted in relatively complex calculation
equations. The research indicated that by adopting a simplified material mode, the
calculation obtain the form which more acceptable for implementation in the
technical regulations and in design codes. For that reason, the elastic, linear hardening
material model was adopted. For the initial point of this model, the value
corresponding to the plastic part of total strain, of 0,2% was adopted, which,
combined with the defined strain capacity of the cross-section εcsm which provides an
accurate assessment of the stress value. The slope of the elastic domain of this model
was determined by the value of the modulus of elasticity E = f0,2/ε0,2,el. The slope of
the strengthened domain of Esh was determined by the slope of the straight line which
passes through the point which corresponds to the yield point (ε0,2,el, f0,2) and the end
points determined by the coordinates (0,16εu, fu):
f u  f 0,2
Esh  (7)
0,16 u   0,2,el
where fu and εu are the ultimate tensile strength and corresponding strain value.
Strain εu can be determined by the application of the equation provided in the
Annex C EN1993-1-4 [5]:
f 0,2
u  1 (8)
fu
After the deformation capacity of the cross-section has been determined by using
equation (4), the limit value of the stress can be determined by applying the proposed
analytical material model:
 
f csm  f 0.2  Esh 0,2,el  csm  1 (9)
 
 0,2,el 
Finally, the design resistance of the compressed cross-section, whose slenderness
is lower than 0,68, can be determined using the equation:
Afcsm
N c,Rd  N csm, Rd  (10)
 M0

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

where A is the cross-section area and γM0 is the material partial safety factor according
to EN1993-1-4 [5].
Figure 1 shows the average stress-strain curves obtained by tensile testing of
material properties and by stub column tests [8], and the elastic, linear hardening
material model with a graphical interpretation of the limiting stress fcsm according to
CSM [3].
The influence of cold forming on the improvement of mechanical properties of
material of the stainless steel structures was not analytically included in the existing
Eurocode EN 1993-1-4 [5]. In the recent several years, the research on the specimens
of press-braked and cold-rolled elements were performed and equations to predict the
0,2% proof stress and tensile stress, in the impact zones of the cross-section, were
developed. Rossi et al. [8] proposed an innovative predictive analytical model to
evaluate the enhanced 0,2% proof stress in the flat section and the corner region of
cold formed section which was based on the determination of the plastic strains
caused during the continuous procedure of cold forming of basic steel material. The
authors provided the equation which, in the function of the cross-section area of
corner region and the gross cross-section area, determines the average value of
enhanced 0,2% proof stress for the entire cold formed cross-section. In this way, the
effects of strength enhancement in the material were taken into consideration, and a
more accurate prediction of cross-section resistance is provided.
2.1. Numerical example
A numerical example of the calculation of design resistance of compressed press-
braked C section according to the CSM [3] is presented in this section. The stub
column specimens, whose design calculations is shown here, were tested in the
Materials and Structures laboratory at the Faculty of Civil Engineering, University of
Belgrade [8].
Cross-section geometric and mechanical properties:
h  100 mm b  40 mm t  4 mm ri  8 mm A  653,7 mm2
E  192202 N/mm2 f 0,2  307,3 N/mm2 fu  633,6 N/mm2  u  0,515  0,2,el  0,0016
92 / 4
Cross-section slenderness:  p   0,484
28,4  0,837 4
 csm 0,25
Cross-section deformation capacity:   3,407
 0,2,el 0,4843,6
633,6  307,3
Strain-hardening slope: Esh   4038,4 N/mm2
0,16  0,515  0,0016
Limiting stress: f csm  307,3  4038,4  0,0016  3,407 1  322,8 N/mm2
Cross-section resistance according to CSM: N u,csm  322,8  653,7  211 kN
Cross-section ressistance according to EN 1993-1-4: N u,EC  200,9 kN
Test ultimate load: N u,test  247,6 kN

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

When the values of the cross-section resistance according to CSM and Eurocode
are compared with the test value, it can be concluded that CSM [3] provided a
considerably better prediction of the cross-section resistance in comparison with the
recommendations provided in the EN 1993-1-4 [5].

3. CONCLUSIONS
The continuous strength method [2],[3] represents an alternative approach in the
calculation of stainless steel cross-section resistance with the generally accepted
cross-section classification approach (or limit slenderness). Its application is limited
to the stocky cross-sections where local buckling occurs in the inelastic stress domain
and whose slenderness is  p  0,68. All recent researches indicated that this method
provides a higher agreement of design and experimental values of cross-section
resistance, so the professional public expects that it will be introduced in the new,
revised version of EN 1993-1-4 [5].

REFERENCES
[1] Dobric J, Markovic Z, Budjevac D, Flajs Z. Specific features of stainless steel
compression elements. Gradjevinar, 67 (2), 143-150, 2015.
[2] Gardner L. The continuous strength method. Proceedings of the Institution of
Civil Engineers - Structures and Buildings, 161(3), 127–33, 2008.
[3] Gardner L, Afshan S. The continuous strength method for structural stainless
steel design. Thin-Walled Structures 2013; 68, 42–49.
[4] Schafer B, Adany S. Buckling analysis of cold-formed steel members using
CUFSM: conventional and constrained finite strip methods. The 18th
international specialty conference onc old-formed steel structures, 39–54, 2006.
[5] EN 1993-1-4:2006 Eurocode 3. Design of Steel Structures: General rules.
Supplementary rules for stainless steels, CEN, 2006.
[6] EN 1993-1-1:2005 Eurocode 3. Design of Steel Structures: General rules and
rules for buildings. CEN, 2005.
[7] Gardner L, Nethercot D. Experiments on stainless steel hollow sections — part
1: material and cross-sectional behaviour. Journal Constructional Steel Research,
60(9),1291–318, 2004.
[8] Dobric J. Behaviour of built-up stainless steel members subjected to axial
compression. PhD thesis, University of Belgrade, Faculty of Civil Engineering;
May 2014.
[9] Rossi B, Afshan S, Gardner L. Strength enhancements in cold-formed structural
sections — Part II: Predictive models. Journal Constructional Steel Research,
83,189-196, 2013.

[34]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Vladimir ŽIVALJEVIĆ
Dušan KOVAĈEVIĆ2

TESTFRAME - LABORATORY FRAME FOR LOAD TEST OF

STRUCTURAL ELEMENTS
Abstract: This is a review of initial version of TestFrame - the laboratory frame for experimental
research of structural elements by test load. Structure of the frame is designed as assembly-disassembly,
free-standing and multipurpose, according to criterion of ability of testing of line (beam, column) and
surface (plate, wall, shell) structural elelemnts made by various building materials.
Development of this version of TestFrame was made simultaneously in two variants of FEM model: with
line FE and with shell FE. Conections (bolts and welding) are modeled as rigid by use of special link
FEs. Model is made in AxisVM® Ver 13.1e FEM software in the master degree thesis on Department
for Civil Engineering and Geodesy, Faculty of Technical Sciences in Novi Sad.

Кey words: TestFrame, AxisVM, FEM model, Test by Load.

TESTFRAME - LABORATORIJSKI OKVIR ZA ISPITIVANJE

KONSTRUKCIJSKIH ELEMENATA PROBNIM OPTEREĆENJEM
Rezime: Ovo je prikaz inicijalne verzije TestFrame - laboratorijskog okvira za eksperimentalno
ispitivanje konstrukcijskih elemenata probnim opterećenjem. Konstrukcija okvira je koncipirana kao
montažno-demontažna, slobodno-stojeća i višenamenska po kriterijumu mogućnosti ispitivanja linijskih
(grede i stubovi) i površinskih (ploĉe, zidovi, ljuske) konstrukcijskih elemenata od razliĉitih
graĊevinskih materijala.
Razvoj ove verzije TestFrame raĊen je paralelno u dve varijante MKE modela: sa linijskim i površinskim
konaĉnim elementima. Veze (zavrtnji ili zavarivanje) su modelirane kao krute, primenom specijalnih KE
veze. Model je uraĊen u MKE softveru AxisVM® verzija 13.1e kao tema master rada na Departmanu za
GraĊevinarstvo i Geodeziju, FTN - Novi Sad.

Ključne reči: TestFrame, AxisVM, MKE model, Probno opterećenje.

1
Master, zivaljevic.vladimir@gmail.com
1
Prof. Dr, Department for Civil Engineering and Geodesy, Faculty of Тechnical Sciences, University of Novi
Sada, Trg D. Obradovića 6, 21000 Novi Sad, dusan@uns.ac.rs

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. INTRODUCTION
This paper describes purpose, topology and modeling of structural behaviour of
laboratory test frame for load testing of various structural elements. For modeling, a
design software AxisVM® Ver 13.1e was used. Geometry and topology were
carefully defined bearing in mind that test frame structure needs to satisfy
requirement such as easy everyday use and manipulaton and to have sufficient
stiffness in order to ensure safe and proper load tests. In that sence, frame is
constructed as assembly-disassembly, with a few elements that change their position
depending on the element being tested, which allow a great variety of structural
elements to be tested. The frame is built out of steel S355 quality, while all
connectors are bolts class 10.9. At the most loaded joints, bolts are preloded.
5600
1 1-1
5300
3100

1
2146 6100 2146 1725 1000 1725
10392 4450

Figure 1 – General disposition with main dimensions of the test frame

2. TESTFRAME: PURPOSE, GEOMETRY, TOPOLOGY AND DESIGN

Test frame is designed for laboratory tests of different structural elements. Being
an assebly-disassebly frame, it is designed with two different types of elements:
 Elements that are present the whole time during tests, no matter which type
and size of structural element is tested
 Elements whose existance and position depend on the test configuration.
Elements that are supposed to be tested are:
 Beams (max 5.0m long)
 Columns (max 2.5m high)
 Slabs (max dimensions 4.2x4.2m)
 Walls (max dimensions 4.0x3.0m)
In consideration of aforementioned, five frame configuration are set apart: two
configurations for beam tests and one configuration for each of the remaining test

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

elements. Two configurations for beam test differ in a way that one configuration
represents load test with one hydraulic jack and the other configuration represents
load test with two hydraulic jacks. These frame configurations are shown in figures
below.

Figure 2 – Beam load test with one Figure 3 – Beam load test with two
hydraulic jack hydraulic jacks

Figure 4 – Column load test Figure 5 – Slab load test

Figure 6 – Wall load test

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

3. MODELING OF STRUCTURAL BEHAVIOR: AXISVM®

Test frame was modelled in AxisVM® Ver 13.1e FEM software. Building
material that was used for modelling is steel material of S355 quality with
yield/ultimate strengths fy/fu=355/510MPa, modulus of elasticity of E=210GPa and
mass density ρ=7850kg/m3. Basic cross-section properties of the frame elements used
in FEM model are given in figure 7.
The structural analysis was first conducted in a variant where all structural
elements are presented as line FE. Purpose of this variant was to preliminary define
cross-section properties of structural elements. Moreover, internal forces at end points
of line FE provided needful information for joint calculation.
Considering the eccentricity of joints, link FE were used to connect nodes of
different structural elements. Values of stiffness components of link FE within the
frame structure were defined as 1E+10kN/m. This means that all joints were
considered as perfectly rigid. Instead of link FE, rigid FE could be used, but
considering the flexibility of modeling of various interface conditions, link FE were
found to be an optimal choice.
In the second variant all structural elements were modelled as shell FE. This
model was used to determine stress values in structural elements more accurately. At
some points, values up to 1300MPa had been registered, which are a few times
greater values than the corresponding values of the line FE model. For comparison,
values in the line FE model reach 285MPa. Stress concetrations in shell FE model
were reduced by various constructive measures. These constructive measures include
placing vertical web stiffeners along elements, enlarging the value of thickness of
webs and stiffeners, as well as shaping structural elements and joints in a way that
was not possible in the variant with line FE. As a result, stress concentrations were
cut down to 423MPa. Although the value of 423MPa exceeds the material yield
strength fy=355MPa of the steel S355, ultimate strength fu=510MPa is not reached.
Moreover, values of 420MPa occur at a few points in the most stressed test
configuration, in zones of 20mm around the nodes. In nearby nodes, stress values
decrease rapidly, below the yield strength. This is completely justified in structural
engineering sense because probality of appearance of unfavorable combination of
stresses is negligible according to real interface conditions in the contact zones
between specimens and test frame.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Figure 7 – 3D view of stress distribution - Stress concentracion points where hydraulic jack is
connected to the frame

Figure 8 – Stress concentracion points – Values that exceede material yield strength

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Figure 9 – FEM model of the test frame (shell FE-variant)

In a line FE-variant, supports were modelled as line supports with stiffness

characteristics that simulate simply supported beam along the entire length.
Furthermore, nonlinear parameters which allow supports to be active only in
compression were assigned to each direction. As a consequence, nonlinear analysis
had proved that regardless of the test load and frame configuration, support reactions
due to test load would always be equal to zero. The same treatement of supports was
applied in a surface FE-variant, with only difference that supports were modelled as
surface supports.
Hydraulic jacks were modelled as beam FE with hinges around y and z local axes
at both ends. In the line FE-variant, hydraulic jack is connected with the frame in one
node. However, in shell FE-variant hydraulic jack is connected with the frame in four
nodes with four rigid link elements. Therefore, stress concentration is from one node
distributed to four nodes. The load which simulates the test load of hydraulic jack was
introduced as a fault in length of the beam FE. The fault in length was determined
iteratively in the following way: Firstly, test samples were defined for each
configuration. Secondly, the deflection and internal forces of the test elemets due to
failure were determined. The above mentioned deflection (hereinafter: critical
deflection) was a start fault in legth of the ˝hydraulic jack˝ in the iterative process.
The fault in legth was increased with evry iteration until the deflection of the test
element in the model coincided with the critical deflection of the element.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

In figures 10 and 11 model information and analysis parameters of line- and shell
FE-variant is given for comparison.

Figure 10 – FEM model data (line FE-variant)

Figure 11 - FEM model data (shell FE-variant)

4. FUTURE DEVELOPMENT PLANS

Future development plans are oriented towards commercial distribution of the test
frame. The frame configuration that will be more flexible in terms of variety of test
specimens will be developed. These measures are directed towards the improvement

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

of the topology of the test frame and addition of new structural elements that will
satisfy requirements of new test configurations.

5. CONCLUSIONS
A comprehensive numerical comparison between the line and shell FE-variant has
been carried out. Results of the line FE-variant suggest that yield strength of the steel
is not reached. However, results of the shell FE-variant confirm that not only values
of yield, but also ultimate strength are almost three times smaller than the highest
value in the model. Therefore, shell FE model should be used for numerical analysis,
because it offers a possibility to introduce minor changes to the model that affect a
great deal in results.
Because of the fact that in reality structural elements are often connected in a way
that their system axes do not intersect within the physical boundaries of the elements,
internal forces due to eccentricity must be taken into account. For this purpose, link
FE should be used.
One of the assumptions defined before the numerical analysis was that vertical
reactions during the load test will remain the same as the reactions due to self weigth
of the frame and element being tested. This assumption could only be proven by the
use of nonlinear analysis, where nonlinear characteristics were assigned to each
support direction. Supports were supposed to be active only in compression. After a
certain number of increments in nonlinear analysis, value of vertical reaction due to
the load test converge to the value due to self weigth of the frame and specimen.

ACKNOWLEDGEMENTS
The presented paper has been done within the research project "Development and
Application of Contemporary Procedures for Design, Construction And Maintenance
Of Buildings", in 2015. on Department for Civil Engineering and Geodesy, Faculty of
Technical Sciences, Novi Sad.

REFERENCES
[1] AxisVM® 13 (2015): User's manual, InterCAD, Budapest
[2] Kovaĉević, D. (2006): FEM Modeling in Structural Analysis (in Serbian),
Belgrade: GraĊevinska knjiga
[3] Kovaĉević, D. (2007): Some aspects of FEM modeling of nonlinear behavior of
civil engineering structures (in Serbian), Invited lecture, Belgrade: Mathematical
Institute of SASA
[4] Živaljević V. (2015): TestFrame - Laboratory Frame for Test by Load Of
Structural Elements, Master degree thessis, Department for Civil Engineering
and Geodesy, Faculty of Technical Sciences, Novi Sad

[42]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Damir ZENUNOVIC
Radomir FOLIC2
Mirsad TOPALOVIC3
Eldar HUSEJNAGIC4

ANALYSIS OF SITE EFFECTS ON BRIDGE STRUCTURE BY

AMBIENT VIBRATION MEASUREMENTS
Abstract: In the framework of the NATO Project SfP 983828 ambient vibration tests and geophysical
investigations were performed. The aim of the research was the definition of the dynamic
characteristics of bridges on the example. The bridge across the river Bosnia near Sarajevo and the
soil surrounding the bridge were instrumented. In this paper comparative analysis of geophysical
investigations and ambient vibration tests of bridge and soil were presented. The results of the
analysis demonstrate the usefulness of ambient vibration tests for identification of the site effects on
bridge structure performance.

Кey words: ambient vibration, bridge structure performance, site effect

ANALIZA UTICAJA TLA NA KONSTRUKCIJU MOSTA

MERENJEM AMBIJENTALNIH VIBRACIJA
Rezime: U sklopu projekta NATO SfP 983828 urađena su ispitivanja ambijentalnim vibracijama i
geofizičkim istraživanjima. Svrha istraživanja bila je definisanje dinamičkih karakteristika tla na
konkretno karakterističnom primeru. Na mostu preko reke Bosne kod Sarajeva i tlu oko mosta su
postavljeni instrukemnti prema programu ispitivanja. U ovom radu je prezentirana uporedna analiza
geofizičkih istraživanja i ispitivanja ambijentalnim vibracijama mosta i tla. Rezultati analize pokazuju
korisnost ispitivanja ambijentalnim vibracijama kod identifikacije uticaja tla na ponašanje
konstrukcije mosta.

Ključne reči: ambijentalna vibracija, ponašanje konstrukcije mosta, uticaj tla

1
Professor, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla, damir.zenunovic@untz.ba
2
Prof. Emeritus, Faculty of Technical Sciences, Trg Dositeja Obradovica 6, Novi Sad, r.folic@gmail.com
3
Professor, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla, mirsad.topalovic@untz.ba
4
Professor, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla, eldar.husejnagic@untz.ba

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. INTRODUCTION
Implementation of ambient vibration tests for identification of site effects has been
studied over last thirty years. Some examples of experimental studies of the soil-
structure interaction, identified by ambient vibration measurements were presented in
papers [1], [2], [3], [5], [6], [7]. Using ambient vibration measurements analytical
model for soil-structure interaction was developed in the paper [4]. The application of
ambient vibration tests for definition of the response of the surrounding soil as well as
the structure were presented in the paper [8]; it was concluded that site-effects may
increase the structural response beyond the provisions of local Codes or Standards.
Ambient vibration measurements can provide assistance in obtaing the correct design
input values.
This paper presents one part of the research in the frame of the NATO Project
“Seismic Upgrading of Bridges in South-East Europe by Innovative Technologies“,
scheduled by Working Package WP 1.4: On-site non-destructive ambient or forced-
vibration tests of selected bridge prototypes for experimental investigation of
dynamic properties. The authors executed some field measurements and comparative
numerical analysis. Some results of the comparative geophysical investigations are
presented as well as ambient vibration tests of the bridge across the river Bosnia near
Sarajevo and the surrounding soil. The aim of the research was the analysis of
usefulness of ambient vibration tests for identification of the site effects on bridge
structure performance.

2. DESCRIPTION OF THE BRIDGE

The bridge over river Bosnia, close to Sarajevo, is a concrete girder bridge with
five spans of 21+3x25+21m (Fig.1). Superstructure consists of reinforced concrete I
girders with recessed deck. Substructure consists of reinforced concrete abutments
and piers based on the footings.

Figure 1 - Bridge over river Bosnia, close to Sarajevo

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

3. FIELD RESEARCH
3.1. Ambient vibration tests
Ambient Vibration Measurements were performed using Three-axial Geophone
Sensors. The Three-axial Geophones have range of measurement up to 254 mm/s,
with resolution 0.127 mm/s or 0.0159 mm/s, and accuracy +/- 5% or 0.5 mm/s.
Frequency Range is from 0 to 315 Hz.

Figure 2 - Test equipment

Ambient vibration test was made with five geophones. One geophone was used for
the reference point (stationary point) 6R (Fig. 3), while the remaining 4 geophones
moved to individual measuring points according to the arrangement. The arrangement
of the measuring points on the bridge is shown in Fig. 3.

Figure 3 - Test equipment

The network of the measuring points of the surrounding soil was established on
both sides of the bridge. The arrangement of the measuring points on the right cost is
shown in Fig. 4.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Figure 4 - The network of the measurement points on the right coast

Detailed analysis of the ambient vibration measurements on the bridge was

presented in the paper [9]. There is an overview of the dominant frequency of
vibration of the soil on the right coast of the bridge (Table 1) and review of the
dominant frequencies of vibration of the piers, the abutments and the soil around the
abutments and piers (Table 2).

Table 1 - Dominant frequencies of soil vibrations on the right coast

MEASUREM MEASURIN Transv. Vert. Long.
ENT G POINT
6R 6,63 5,05 3,79
1 11,6 2,00 11,7
13:24:26 2 7,47 12,4 15,4
3 15,4 12,2 9,07
4 10,1 2,39 9,62
6R 5,45 5,00 3,97
5 11,8 2,00 2,02
13:33:05 6 11,8 12,1 5,67
7 7,8 12,4 5,67
8 15,2 2,13 13,4
6R 5,53 5,46 3,89
9 2,13 2,00 2,00
13:43:19 10 16,8 21,4 13,00
11 11,9 21,4 2,78
12 2,26 2,01 2,41
6R 5,05 5,05 3,87
13 2,26 2,13 2,26
13:51:56 14 16,5 27,7 17,3
15 21,3 16,4 12,3
16 8,1 2,27 7,94

Two sets of data related to local conditions of measurement can be seen in table 1.
Namely, the areas under the bridge are arranged for the passage of the vehicle for
embankment maintenance; frequency of vertical vibrations are in the range of 12-22
Hz. Frequencies of 2 Hz (Fig.5) are in the areas of natural soil vertical vibrations.
Regularity of measurement results cannot be defined for horizontal vibrations.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Table 2 - Dominant frequencies of pier and abutment vibrations and soil vibrations close to
them
MEASURIN Transv. Vert. Long.
G POINT
ABUTMEN 16,6 2,39 6,28
T 14,1 2,27 5,50
4,99 4,99 5,50
PIER
5,84 17,1 6,37
10* 16,8 21,4 13,00
11* 11,9 21,4 2,78
14* 16,5 27,7 17,3
15* 21,3 16,4 12,3
9** 2,13 2,00 2,00
12** 2,26 2,01 2,41
*
embankment
**
natural soil

Figure 5 - The measurements on the right coast

When comparing with the modes of vibration of the bridge it can be seen that
during earthquake impact there is a possibility of significant effect of soil-structure in
the transverse and longitudinal vibration of the bridge.
3.2. Geophysical investigations
Seismic refraction and seismic tomography were used, with the aim to make detail
determination of the soil profile. The transverse and longitudinal seismic waves were
measured. Based on the measurements the following soil parameters are defined:
shear modulus, elastic modulus and Poisson's ratio. Location and layout of seismic
profiles are presented in figure 6. Determined elastic parameters are presented in table
3.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

a) b)

c)

Figure 6 - Seismic profiles: a) Profile location; b) The characteristic lithology; c) Soil profiles

Table 3 - Soil profile, parameters average values

Depth P-waves Young’s Shear Poisson ratio
(m) (m/s) modulus modulus
(MPa) (MPa)
2 800 801 312 0,36
4 1200 1797 699 0,35
6 1600 3193 1242 0,35
8 2400 7179 2791 0,32
3.3. Finite Element Model (FEM)
The FEMs of the bridge and the surrounding soil with detailed analysis
were presented in [9]. The FEM of the natural soil close to the bridge is
presented (Fig. 7). The soil was modelled with solid elements with modulus E,
determined by geophysics soil measurements (see Table 3).

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

a) b)

c)

Figure 7 – The soil frequencies: a) vertical 2.204Hz; b)transversal 10.742Hz; c)longitudinal

11.849Hz

The frequenices obtained by FEMs, modelled with measured geophysical

parameters, are well matched with frequencies from Ambient Vibration
Measurements (see measuring points of natural soil 1,4,5,8 in Table 1).

4. CONCLUSIONS
From the presented ambient vibration frequencies of the abutments and natural
surrounding soil it can be seen that it is necessary to analyze soil-structure interaction
during the processing of the ambient vibration measurements. Also, from the
presented measurements it can be seen the importance of preparation and landscaping
of the foundation soil for vibration frequencies. If we take into account the soil
vibration frequency range of 2 to 22 Hz, depending on the arrangement of the
measurement points (embankment or natural soil), it can be seen that it has an impact
on the decrease or increase the effect of soil-structure interaction.

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ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the
research project TR 36043 supported by the Ministry for Education and
Science Republic of Serbia. This support is acknowledged (R. Folić).

REFERENCES
[1] Ramirez-Centeno M., Ruiz-Sandoval M.: Experimental study of the soil-
structure interaction effects on three different kinds of accelerometric bases,
Eleventh World Conference on Earthquake Engineering, Paper No.719, 1996.
[2] Turek M., Thibert K., Ventura C., Kuan S.: Ambient Vibration Testing of Three
Unreinforced Brick Masonry Buildings in Vancouver, Canada, Conference:
IMAC-XXIV: Conference & Exposition on Structural Dynamics, 2006.
[3] Tabatabaie M., Sommer S.C.: Analysis of Soil-Structure Interaction due to
Ambient Vibration, Paper: UCRL-JC-130342, Lawrence Livermore National
Laboratory, 1998.
[4] Phan L.T., Hendrikson E.M., Marshall R.D., Celebi M.: Analytical Modeling for
Soil-Structure Interaction of a 6-story Commercial Office Building, Fifth U.S.
National Conference on Earthquake Engineering, Earthquake Awareness and
Mitigation Across the Nation, Vol.1, 1994, pp. 199-208.
[5] Regnier J., Clotaire M., Etienne B., Philippe G.: Contribution of ambient
vibration recordings (Free-field and buildings) for post-seismic analysis: the case
of the Mw 7.3 Martinique (French lesser Antilles) earthquake, november 29,
2007., Soil Dynamics and Earthquake Engineering, Elsevier, 2013, 50, pp. 162-
167.
[6] Suárez L.E., Pando M.A., Ritta R.: Ambient Vibration Measurements for
Estimation of Site Fundamental Periods at the City of Mayagüez, Puerto Rico,
Technical Report, USGS Grant Number: 10HQPAQ0001, University of Puerto
Rico at Mayaguez, May, 2012.
[7] Kopf F., Schäfer D., Pistrol J.: Assessment of Soil-Structure-Interaction by
measurement, Vienna Congress on Recent Advances in Earthquake Engineering
and Structural Dynamics 2013 (VEESD 2013), Vienna, Austria, August 2013,
Paper No. 340.
[8] Wenzel H., Achs G.: Determination of Site Effects by Ambient Vibration
Monitoring, First European Conference on Earthquake Engineering and
Seismology (a joint event of the 13th ECEE & 30th General Assembly of the
ESC), Geneva, Switzerland, September 2006, Paper No. 1320.
[9] Zenunović D., Topalović M., Folić R.: System identification of R/C girder
bridges based on field measurements and numerical solutions, Tehnički vjesnik,
Vol.22, No.3, 2015., str,667-675.

[50]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Tatjana KOČETOV MIŠULIĆ
Dragan MANOJLOVIĆ2

MODELING OF COMPOSITE TIMBER-CONCRETE SYSTEM

WITH INCLINED CROSS SCREWS
Abstract: In cases of modeling the timber-concrete composite behavior by software, it is necessary to be
familiar with slip modulus values of applied mechanical fasteners. The analytical expressions, derived
from numerous experimental investigations, have the essential practical significance in modeling the
composite slip behavior. So haw the expressions for slip modulus of dowel type fasteners given in EN
1995-1 are limited to position of the fastener perpendicular to the timber grains, the theoretical
background for estimation of inclined dowel type fasteners in timber surrounding, as well as analytical
procedures for its estimation, are given in the paper. The illustrative numerical example, with
comparative discussion of obtained structural stiffness depending on applied fasteners angle, is also
given in the paper.

Кey words: timber-concrete, crossed screws, slip modulus, transversal modulus, axial modulus.

MODELIRANJE SPREGNUTOG SISTEMA DRVO-BETON SA

UNAKRSNO POSTAVLJENIM VIJCIMA
Rezime: Pri modeliranju ponašanja spregnutog sistema drvo-beton neophodno je poznavati vrednost
modula pomerljivosti upotrebljenog tipa mehaničkog spojnog sredstva. Upotreba odgovarajućih
analitičkih izraza, nastalih na osnovu mnogobrojnih eksperimentalnih istraživanja, je od velikog
praktičnog značaja. Kako se izrazi za modul pomerljivosti štapastih spojnih sredstava dati u EN 1995-1
odnose samo na smer upravno na vlakna drveta tj. vertikalan položaj spojnog sredstva, u radu su date
teorijske osnove za procenu modula pomerljivosti za štapasta spojna sredstva postavljena pod uglom u
odnosu na drvna vlakna, kao i predložene analitičke procedure. Teorijska podloga je u radu ilustrovana
numeričkim primerom, čiji su komparativni rezultati diskutovani sa ciljem upoređenja krutosti sistema u
zavisnosti od ugla postavljanja spojnih sredstava.

Ključne reči: drvo-beton, unakrsni vijci, modul pomerljivosti, smičući modul, aksijalni modul.

1
PhD, Ass. Prof., University of Novi Sad, Faculty of Technical sciences, e-mail: tanya@uns.ac.rs
2
BSc Civ.Eng, Assist., University of Novi Sad, Faculty of Technical Sciences, e-mail manojlovic.dragan@uns.ac.rs

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. TIMBER-CONCRETE COMPOSITES
Timber-concrete composites (TCC) is a field-proven construction system in which
a relatively thin concrete slab is semi rigidly or rigidly attached to a timber beams by
mechanical fasteners. First applications and pioneer tests on this subject were
conducted in 1942, and until nowadays, because of its efficiency, the system occupies
the engineers' and researchers' attention.
TCC represents very effective combination of the two construction materials that
results in higher load-bearing capacity and rigidity of the system, improved fire safety
and sound insulation. It is very acceptable solution for renovating old structures -
especially timber floors (minimum intervention, the aesthetic aspects of a timber
ceiling complemented by the advantages of concrete, unnecessary expensive
demolition, space underneath can be used during construction), and also suitable for
new structures, such as for floors in multi-storey buildings, timber bridge decks, etc...
1.1. Effective bending stiffness of TCC
The degree of composite action in TCC, that may vary from no composite action
for no connection to full composite action for an infinitely stiff connection, Fig 1, [1],
directly depends on connectors type, arrangements, the way of application i.e.
connection stiffness. The shear connectors are key elements of a composite system
because they have to provide effective shear transfer interconnecting the concrete slab
with timber beam. However, the effective bending stiffness of composite structure is
not in linear correlation with connection stiffness. Bending stiffness of composite TC
system could be increased up to maximum 4 times, in particular cases of geometrical
and material properties combination with infinitely stiff connections, Fig 2, [2].

Figure 1 – Full, Partial and No Figure 2 – Correlation between effective bending

composite action in TCC [1] stiffness and stiffness of shear connections of TCC
floors [2]
1.2. Types and arrangements of shear connectors in TCC
Types of fasteners and methods of their applications as shear connectors in TCC
systems started to develop from typical mechanical fasteners for wood (nails, screws,
bolts, studs, ...) as discrete dowels to technologically advanced continual connections

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

(punched metal plates, steel glued lattices, perforated steel "T" ribs, glued-in, etc...).
One of the first classifications of commonly used methods for interconnecting TC
was given by Ceccotti (1995), and the part A, as most common applied methods in
practice in Serbia, are shown in Fig 3, [1].

Figure 3 – Commonly used joining methods in TCC - Group A, [1]

Group A represents mostly doweled type connectors, such as nails, reinforced steel
bars - studs, long and self-tapping screws, in vertical and inclined position. The
advantages and performance of mentioned methods is deeply investigated and applied
for enforcement of many existing floor structures in Serbia by Stevanovic (1991-
2005), [3]. Although they are considered to be the at least rigid in comparison with
other types (groups) of shear connectors, the advantages of dowel type connectors is
that are inexpensive, practical, easy to handle and install, with the sufficient degree of
composite action related to purpose and function of considered floor structures. In
order to promote the use of TCC systems in Serbia, the presented paper is focused on
computational modelling of such systems by allowable domestic software.
1.3. Standards and relevant research about TCC
Analytical models for calculating stresses and deformations in TCC systems are
generally based on semi-rigid connections between two layers. A simple linear model,
widely used and present in Eurocode 5 [4] is based on Newmark's and Mohler's works
developed in 60's and is so called "" method.
1.3.1. EC 1995-1-1: Annex B and "slip modulus"
The mechanical performance of TCC systems is more influenced by joint slip
modulus than the joint ultimate load-bearing capacity. Dominant factor in "" method,
i.e. in Eqs (1-7), Table 1, is slip modulus for connections "Ks", or according to EC5
"Kser" coefficient, - the target value of numerous experimental and theoretical
verification. Eurocode 5 suggests values for "slip modulus" as a function of
connector's type, it's diameter and specific mass weight of wood, in cases when
experimental data are not available. According to EC5, the "Kser" value for screws
and predrilled nails - dowel type fasteners, is given by Eq (8) for SLS and by Eq (9)
for ULS. Suggested equations are derived for timber-to-timber joints, and for TCC
modelling the values for slip modulus have to be doubled.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Таble 1- Cross-section of TCC and basic equations of "γ" method EC5 [4]
Composite TC cross section "γ / Mohler" method Eq No:
n  Ec E w (1)
  1 (1  k) (2)

k  ( 2  E c  A c  s) (L2  K i ) (3)

a c  0.5  (A w (h w  h c )) (   n A c  A w ) (4)
a w  (h w  h c ) 2  a c (5)

Ief  n  Ic    n  A c  a c 2  I w  A w  a w 2 (6)

“Kser” value for screws and predrilled nails (EC5)

K i  K ser  2  1.5  d 23 (7)
in timber-concrete, SLS
“Ku” value for ULS K i  K u  2 3  K ser (8)

1.3.2. Experimental research about TCC and "slip modulus"

Extensive experimental campaigns conducted in last two decades (Gelfi et al.,
2002 [5], Dias 2005 [2], Lukaszewska 2009 [1], etc..) conflict with EC5 suggestions
for "slip modulus", finding it quite conservative and underestimated for TCC systems.
Some of researchers suggest that the slip modulus should be determined in terms of
fastener diameter and timber's modulus of elasticity.
The proposed values in EC5 do not include the presence of formwork in cross-
section, so the additional research [5], gives the theoretical background and
experimental results for stud connectors stiffness with existing formwork, Eq (9):
12Es Is
Ks  , *
 17.3  0.000572  k c  0.00894  k w  0.880  t  4.34  d (9)
*3

Although the findings have limitations (depth of planks in range t = 0-5cm, stud
diameter from 12 to 20mm), given analytical expression is very suitable for
modelling, giving the good results for everyday practice [6].

2. INCLINED CROSS FASTENERS - THEORETHICAL BACKGROUND

Suggested expressions, Eqs (8-9) by Eurocode 5, as well as different proposed
values for slip modulus given by number of researchers, represent the slip modulus in
shear, i.e. Kser=Ks= K  that considers the vertical position (perpendicular to the
timber grain direction) of mechanical fastener, Fig 3 (A1-3). For the very common
cases in practice of inclined and crossed dowel type fasteners in TCC systems, Fig 3
(A4), there is no suggested values for axial slip modulus Kax,ser= K II in EC5, although
cases of inclined dowel type fasteners are discussed in details for load-bearing
capacity with quadratic combination of the axial and lateral behaviour.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

2.1. Inclined fasteners and correspondent stiffness (slip modulus)

The lack of proposed values for calculation of inclined screws stiffness induced
several theoretical and experimental works (Bejtka & Bla 2002, [7], Tomasi & alt.,
2010, [8]). The basis of result formulation was quadratic form proposed by EC5, for
axial and lateral displacements and stiffness, Eqs (10-13), Table 2.

Таble 2- Inclined fasteners in timber-to timber connections and basic equations [8]
Inclined fasteners - experimental arrangements: a) compression, b) tension, c) cross X

a) b) c)

where equations Eq No:

 ,   ,  II - lateral displ., components      cos   II    cos  (10)
 - angle of inclination
K ser  Fser  (11)
K  - lateral stiffness (shear stiffness) K ser,  K   cos   (cos     sin ) 
(12)
K II - axial stiffness  K II  sin   (sin     cos )
 - friction coefficient at the interface K ser,  K   cos 2   K II  sin 2  (13)
between wood elements

Findings by Tomasi & alt. [8], shown that:

 for timber in shear-compression the slip modulus value could be adopted as slip
modulus in shear (a), i.e. according to Eq (7),
 for timber in shear-tension the stiffness grows with angle, reaching maximum in
bi.e. according to Eq (13),
 X crossed fasteners give the maximum values of stiffness (c).
The question of axial slip modulus, i.e. slip modulus parallel to the grains, is still
opened and experiments conducted in order to determine this values show large
variations of results (Dietsch & Brandner, 2015, [9]). Two often proposed expressions
for Kax,ser= K II for self-tapping screws are given by Eqs (14-15).

K II  K ser,ax,i  780  d 0.2  ef

0.4
(14) K II  K ser,ax,i  30  s g  d (15)
Where is: sg - embedment length, in mm
d - outer diameter of screws thread in mm d - outer diameter of screws
lef - penetration screw length in timber, mm thread in mm

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3. MODELLING OF TCC SYSTEM WITH INCLINED CROSS SCREWS

The basic idea of this paper is to promote the benefits of TCC in practice, giving
practical advices for modelling the system by domestic software packages that do not
contain database about slip modulus of fasteners in TC surrounding. The modelling is
done with software package "Radimpex" Tower 7, based on SRPS regulative. The
model is based on a Vierendeel beam analogy, Table 3. The structural analysis is
made using 1st order theory, and model was made using beam elements. X screws
were modelled with beam elements that link central lines of concrete slab and timber
beam. Slip modulus of connectors is introduced trough stiffness of "link" element,
where "link" element stiffness Kl is equal to slip modulus of inclined X screws
Kserobtained from Eq (13). The length of "link" element is adopted as h* Eq (16).
As link element is fixed end beam with stiffness given with Eq (17), the "substitute"
connector diameter d* is necessary to find from Eq (18) for further modelling.

Table 3 - Modeling of TCC beam

Vierendeel beam analogy Eq No:
*
h  0.5  (h c  h w ) (16)
12E I
K  K ser, 
h*
(17)

*
64 K ser,  h
d*  4  (18)
12 E

4. NUMERICAL EXAMPLE OF TCC FLOOR STRUCTURE

Disposition of elements, dimensions, connectors' arrangements and applied
materials adopted for numerical example computation are shown at Fig 4.

Figure 4 – Design example with two arrangements of fasteners and material characteristics

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

In order to compare the effective bending stiffness, degree of composite action,

stress distribution and deflection, two arrangements of connectors (vertical and X
cross) are used in the design example of real floor structure with span of 5m. The
degree of partial composite action is determined on the basis of full and no composite
action, varying the spacing of the screws in the range of e=10-50 cm. Three models
were computed and compared: Model 1 - vertical position of 2 self-tapping screws,
shear slip modulus according Eq (7), Model 2 - X position of screws, axial slip
modulus according Eq (14), and Model 3 - X position of screws, axial slip modulus
according Eq (15).
 Model-1: Kser,α= Kser= K⊥ (Kser according EC5)
2 2
 Model-2: Kser,α=K⊥∙cos α+KII∙sin α (K⊥=Kser, KII= Kser,ax,i= 780∙d0.2∙lef0.4)
2 2
 Model-3: Kser,α=K⊥∙cos α+KII∙sin α (K⊥=Kser, KII= Kser,ax,i= 30∙sg∙d)

5. DISCUSSION OF RESULTS
The results of analysis are shown at Fig 5. Level of composite action is determined
on the basis of full composite action. Basically, Model 1 (with vertical screws) shows
the lowest degree of TC composite action, what was expected, while Models 2 and 3
(with X screws) show mutual differences of about 8%, depending on adopted
expression for axial stiffness. Deflection of all models/varied spacing is in proscribed
limits. Model 3 shows the most favorable results in all aspects. For the degree of
composite TC action of 35% , without exceeding the concrete tensile strength, Model
1 has fasteners' spacing of 20-25cm, Model 2 of 30-40cm and Model 3 of 50cm.

Degree of partial Stress distrubution for

composite action
Degree of partial

Full
composite action Model-1 co
Beam height [cm]

M mp
100% 50 osit
0% o… 0
e
1015203050 -1000 0 1000
Spacing of screws Stress [N/cm2]

Stress distrubution for Stress distrubution for

Full Full
Model-2 co
Model-3 co
Beam height [cm]

Beam height [cm]

mp mp
50 osit 50 osit
0 0
e e
-1000 0 1000 -1000 0 1000
Stress [N/cm2] Stress [N/cm2]

Figure 5 – Degrees of partial composite action and

stress distribution trough TC cross-section for analyzed models (1-3)

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

6. CONCLUSION
Although dowel type fasteners are considered as ductile, their application is
confirmed as convenient in the practice (easy, inexpensive) and satisfactory effective
for the restoration of buildings timber floors. Screws inclined in X direction provide
higher stiffness than vertically placed, so the same flexural stiffness could be
achieved with fewer screws. With commercial domestic software packages, that do
not include databases with experimental results of "slip" modulus in TCC,
engineering problems could be satisfactory solved by given relatively simple
modeling, code's and empirical analytical expressions. For detailed modeling, it is
necessary to apply more sophisticated modelling approach, [10].

ACKNOWLEDGEMENT
This paper is supported by the research project TR 36043 "Development and
application of a comprehensive approach to the design of new and safety assessment
of existing structures for seismic risk reduction in Serbia", financed by the Ministry of
Science of Serbia.

REFERENCES
[1] Lukaszewska, E., 2009. Development of prefabricated timber-concrete
composite floors. PhD thesis, Department of Civil, Mining and Environmental
Engineering. Division of Structural Engineering, Luleå, Sweden, 318p.
[2] Dias, A.M.P.G., 2005. Reinforcement of timber floors using lightweight concrete
– Mechanical behaviour of the connections. Ph.D. thesis, University of Coimbra,
Coimbra, Portugal, 303p.
[3] Stevanović, B., 2004. Eksperimentalna i teorijska analiza spregnutih nosača
drvo-beton izvedenih mehaničkim spojnim sredstvima. Materijali i konstrukcije,
Beograd, vol. 47, № 1-2, pp. 29-46.
[4] EN 1995-1-1:2004, 2009. Proračun drvenih konstrukcija, deo 1-1: Opšta pravila i
pravila za zgrade, Beograd, Građevinski fakultet Univerziteta u Beogradu, 133p.
[5] Gelfi, P., Giuriani, E., Marini, A., 2002. Stud Shear Connection Design for
Composite Concrete Slab and Wood Beams. JSE, pp. 1544-1550.
[6] Manojlović, D., Kočetov Mišulić, T., 2015. Slip modulus in wood-concrete
composites: Practical estimation for modelling. International Conference Proc.:
Contemporary achievements in civil engineering, FCE Subotica, pp. 253-259.
[7] Bejtka, I., Blaß, HJ., 2002. Joints with inclined screws. International council for
research and innovation in building and construction, CIB, W18 – Timber
Structure.
[8] Tomasi, R., Crosatti, A., Piazza, M., 2010. Theoretical and experimental analysis
of timber-to-timber joints connected with inclined screws. Construction and
Building Materials 24, pp. 1560–1571.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[9] Dietsch, P., Brandner, R., 2015. Self-tapping screws and threaded rods as
reinforcement for structural timber elements: A state-of-the-art report.
Construction and Building Materials, Volume 97, pp.78–89.
[10] Persaud, R., Symons, D., Stanislaus, H., 2010. Slip modulus of inclined screws
in timber–concrete floors. Structures and Buildings 163, pp.245-255.

[59]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Dušan KOVAĈEVIĆ
Ranko OKUKA2
Igor DŽOLEV3

AXISVM® 13 - ADVANCED FEATURES OF FEM

SOFTVARE FOR STRUCTURAL ANALYSIS
Abstract: This is a review of advanced features of new version of AxisVM® FEM software. In addition
to standard options, AxisVM® 13 offers sophisticated possibilities of modeling and structural analysis.
Besides the nonlinear static and dynamic analysis of line and surface structures based on the general
geometric nonlinear theory (large displacements, large strains) now is possible an material nonlinear
analysis with variant of "gradual cross-section's plastification" concept (finite layer approach). Load
section consists automatic creation of wind and snow actions and and design options section treats all
common structural materials and most of mainstream national design codes.
On Department for Civil Engineering and Geodesy, FTN - Novi Sad, AxisVM® is used in education, in
research work and for expert tasks of design practice.

Кey words: AxisVM, FEM modeling, CASA

AXISVM® 13 - NAPREDNE MOGUĆNOSTI MKE

SOFTVERA ZA ANALIZU KONSTRUKCIJA
Rezime: Ovo je prikaz naprednih mogućnosti nove verzije MKE softvera AxisVM® za analizu
konstrukcija. Pored standardnih opcija AxisVM® 13 nudi i sofisticirane mogućnosti modeliranja i
analize konstrukcija. Uz nelinearnu statiĉku i dinamiĉku analizu linijskih i površinskih konstrukcija
zasnovanu na opštoj geometrijski nelinearnoj teoriji (velika pomeranja, velike deformacije) sada je
moguća i materijalno nelinearna analiza sa varijantom postupne plastifikacije preseka (metoda konaĉnih
slojeva). Sekcija za opterećenja je dopunjena automatskim generisanjem opterećenja vetrom i snegom, a
opcije dimenzionisanja obuhvataju sve uobiчajene konstrukcijske materijale i većinu glavnih
nacionalnih standarda.
Na Departmanu za graĊevinarstvo i geodeziju, FTN - Novi Sad AxisVM® se koristi u nastavi, u
istraživaĉkog radu i za ekspertske zadatke projektantske prakse.

Ključne reči: AxisVM, MKE modeliranje, numeriĉka analiza konstrukcija

1
Prof. Dr, University of Novi Sad, Faculty of Тechnical Sciences, Department for Civil Engineering and Geodesy
dusan@uns.ac.rs
2
Master, okukaranko@yahoo.com
3
Master, University of Novi Sad, Faculty of Тechnical Sciences, Department for Civil Engineering and Geodesy
igordzolev@gmail.com

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1. INTRODUCTION
AxisVM® is FEM modeling software developed for a Microsoft Windows® by
structural engineers (by InterCAD company, Hungary) and intended for structural
engineers [1]. Due to its wide modeling capabilities, AxisVM is verified as successful
in design of large complex structures and simple buildings.
The software performs linear and nolinear, static and dynamic analysis of line and
surface, plane and space structures. It enables analysis of structural models without
any limits regards to number of nodes and FE.

2. MODELING OF GEOMETRY AND TOPOLOGY:

AXISVM® PRE-PROCESSOR
AxisVM® (Visual Modeling) with very intuitive graphical user interface provides
easy creation and display FEM model what is important in procedures of new FEM
software training. Fig. 1 shows AxisVM® working environment.

Figure 1. AxisVM® desktop

AxisVM pre-procesor editor enables:

 geometry modeling in 2D or 3D with geometry generation commands
(translate, rotate, mirror, scale, with multiple copy or move),
 graphical editing of the model in any view including the perspective view,
 powerful selection tools (filtered selection available), view changes at the click
of the mouse,
 working on parts (allows easy editing of most complex 3D geometries and
includes advanced part management),
 wire frame modeling and rendered display for better model check (see Fig. 2),
 search for entities by type and index and automatic duplication check feature,

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 graphically created joints, members, finite elements, properties, constraints,

releases and loadings,
 cross-section and mateiral libraries with most of the available European and
U.S. sections and mateirals and creation of custom libraries and
 fully integrated graphical cross-section editor for complex shapes (all cross-
sectional properties are automatically calculated based on the graphical input).

Figure 2. AxisVM® rendered model display example

Structural geometry, materials, cross-sections, loads, supports etc. can also be

imported from latest version of IFC files, as well as curved elements and elements
with variable cross-section, loads, load cases and load groups.
The user can merge other AxisVM models to create a new model, thus allowing
parts of the structure to be modeled by different users/departments.

3. MODELING OF STRUCTURAL BEHAVIOR: AXISVM® PROCESSOR

AxisVM implements an object-oriented finite element architecture that inherits
more reliability than the classical systems. It provides a variety of finite elements for
modeling frames and/or surface structures, special elements for modeling boundary
conditions and connections and elements with nonlinear capabilities:
 line elements: truss, beam, rib (the truss and the cubic beam element are the
most widely used finite elements for bar, beam, or column modeling. The rib
element is a 3-node isoparametric element with quadratic displacement
interpolation that can be used similar to the beam element (but takes into
account the shear deformations) or in conjunction with surface elements for
eccentric rib modeling),
 surface elements: membrane, plate, shell (these elements are isoparametric
quadrilateral (8/9-node) or triangular (6-node) elements, that use quadratic

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shape functions to interpolate displacements, and pass the patch test for
arbitrary shape (the plate and shell elements use Mindlin's plate assumptions in
a Heterosis formulation, see Fig. 3)), [2]
 conversion of line elements (beams, ribs) with steel cross section to shell
elements,
 conversion of beam connections to shell elements,
 Winkler type elastic supports for line and surface elements can model elastic
foundation support conditions of line and surface elements with nonlinear
characteristics - tension or compression only, limited resistance,
 joint support elements with arbitrary orientation and stiffness can have a
specified stiffness, and the resulting internal forces are the support reactions
with nonlinear characteristics - tension or compression only, limited resistance,
 gap, spring, link and rigid special FE for modeling of particular structural
phenomena, etc.

Figure 3. AxisVM shell FEs modeling example

Various loads can be applied on the nodes and the finite elements. Up to 99 load
cases can be applied on a model and any number of load combinations can be
generated from these load cases. Load cases can be classified in load groups for
automatic critical internal force calculations.
Finite element mesh generation is possible using triangular, quadrilateral, as well
as mixed triangle-quadrilatetal finite elements.
AxisVM performs most of the analyses, typical in the practical design of civil
engineering structures:
 linear static analysis,
 buckling analysis: critical force and shape computation (Fig. 4),

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 nonlinear static analysis: displacement/force controlled incremental iterative

solution,
 free vibration analysis: eigen-shape and -frequency computation (Fig. 5),
 dynamic and earthquake analysis - response spectrum, time history and push
over analysis - Eurocode 8, ISA (Italian), STAS (Romanian) and MSz
(Hungarian).

Figure 4. Example of AxisVM 3rd order buckling analysis

Clearly, in application of CASA software, it is not sufficient to know only the

basic problem and the essence of the applied method, but also to know the software
performances (in sense of possibilities and limits), numerical methods and a critical
approach in interpretation and application of the obtained results [3, 4].

Figure 5. AxisVM free vibration analysis of bridge example

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4. RESULTS DISPLAY AND DESIGN: AXISVM® POST-PROCESSOR

Civil engineers use AxisVM for the analysis of structures with confidence that
their final engineering product will meet their country specific design codes. The ease
of results exporting allows each user to connect AxisVM to almost every locally
produced and national code compliant design and detailing software. AxisVM is
committed to assisting each user in connecting the results of the finite element
calculations to the programs they use every day.
AxisVM provides multi-window model analysis results display and design
capabilities:
 diagram analysis results display,
 analysis results display for section lines,
 analysis results display for structure parts,
 isosurface analysis results display 2D or 3D (Fig. 6),
 piled foundations design according to Eurocode 7,
 plate deflection calculation according to Eurocode 2, NEN (Dutch), MSz
(Hungarian, STAS (Romanian),
 steel design according to Eurocode 3, NEN 6770/74,
 timber design according to Eurocode 5 EN 1995-1-1:2004,
 reinforced concrete design (beams, columns, plates, membranes, shells)
according to Eurocode 2 (Fig. 7c), NEN (Dutch), DIN (German), SIA (Swiss),
 integrated Report Generator to create report templates for every construction
partner: design approval, steel detailer, bid estimates, component producers,
and departmental specialties,
 detailed documentation of strength and stability checks using formulas and
substituted values,
 3D PDF file export of the graphical content, which can be rotated and zoomed
in and out within the PDF reader.

Figure 6 – Analysis results display - space roof structure

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5. CONCLUSIONS
AxisVM® is based on FEM as a dominant numerical concept. Due to great
possibilities of software implementation (automatic FE mesh creation, the formation
and solving of constitutive equations, numerical and graphic presentation of the
results, etc.) FEM has become a dominant method of numerical modeling of complex
structural problems.
Development, distribution and application of FEM software is the area where the
professional competence is essential, but provided that rather high education in the
field of computer sciences is also possessed. Very similar relations apply when
distribution and, particularly, program application are in question. AxisVM® is
developed by engineers for engineers.
Education and, especially, examination of the knowledge in the primary profession
should be adapted, first, to need of complete understanding of the essence of
structural behavior. Gaining of the "encyclopedia like" knowledge by studying of
many methods for analysis possibly provides wide education and contributes to the
technical culture, but it takes away attention and energy and ruins enthusiasm of
students. Such knowledge is not necessary in the competent use of FEM software. All
this reasons cause introduction of AxisVM® software in course "FEM Modeling in
Structural Analysis".

ACKNOWLEDGEMENTS
The presented paper has been done within the research project "Development and
Application of Contemporary Procedures for Design, Construction And Maintenance
Of Buildings", in 2015. on Department for Civil Engineering and Geodesy, Faculty of
Technical Sciences, Novi Sad.

REFERENCES
[1] AxisVM® 13 (2015): User's manual, Budapest: InterCAD,
[2] Cook, R.D (1995): Finite Element Modeling for Stress Analysis, John Wiley &
Sons, Inc.
[3] Kovaĉević, Dušan (2006): FEM Modeling in Structural Analysis (in Serbian),
Belgrade: GraĊevinska knjiga
[4] Kovaĉević, Dušan (2007): Some aspects of FEM modeling of nonlinear behavior
of civil engineering structures (in Serbian), Invited lecture, Belgrade:
Mathematical Institute of SANU

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NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Dragan D. MILAŠINOVIĆ
Dijana MAJSTOROVIĆ2
Radovan VUKOMANOVIĆ3
Nataša MRĐA4
Radomir CVIJIĆ5

STATIC AND DYNAMIC INELASTIC BUCKLING OF THIN-

WALLED STRUCTURES USING THE FINITE STRIP METHOD

Abstract: This paper aims at providing a unified frame for quasi-static and dynamic inelastic buckling of
uniformly compressed plate structures using the finite strip method. The elastic properties of the material
are determined using the propagation of mechanical waves. The nonlinear behavior of the material is
invoked using the rheological-dynamical analogy. According to the analogy, a very complicated
nonlinear problem in the inelastic range of strains is solved as a simple linear dynamic one. The
orthotropic constitutive relations for inelastic buckling are derived and a new modulus iterative method
for the solution of nonlinear equations is presented.

Кey words: finite strip method, inelastic buckling, modulus iterative method

STATIČKO I DINAMIČKO NEELASTIČNO IZVIJANJE

TANKOZIDNIH NOSAČA METODOM KONAČNIH TRAKA
Rezime: Cilj ovog rada je da obezbjedi jedinstven okvir za kvazi-statičko i dinamičko neelastično
izvijanje pritisnutih pločastih konstrukcija korištenjem metoda konačnih traka. Elastične osobine
materijala su određene korištenjem propagacije talasa. Nelinearno ponašanje materijala se rješava
metodom reološko-dinamičke analogije. Prema analogiji, veoma komplikovan nelinearan problem u
neelastičnom području deformacija se rješava kao jednostavan linearan dinamički problem. Dobijene su
ortotropne konstitutivne jednačine neelastičnog izvijanja, i predstavljen je novi iterativni metod
rješavanje nelinearnih jednačina.

Ključne reči: metod konačnih traka, neelastično izvijanje, iterativni metod

1
University of Novi Sad, Faculty of Civil Engineering Subotica, Kozaračka 2a, Serbia, ddmil@gf.uns.ac.rs
2
University of Banjaluka, Faculty of Architecture, Civil Engineering and Geodesy, BiH, dijanam@aggfbl.org
3
University of Banjaluka, Faculty of Architecture,Civil Engineering and Geodesy, BiH, rvukomanovic@aggfbl.org
4
University of Banjaluka, Faculty of Architecture, Civil Engineering and Geodesy, BiH, mnatasa@aggfbl.org
5
University of Banjaluka, Faculty of Architecture, Civil Engineering and Geodesy, BiH, rcvijic@aggfbl.org

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1. THEORETICAL BACKGROUND
The purpose of this paper is to investigate some new mechanical aspects of
uniformly compressed plate structures. These are structures which are generally made
by joining flat plates at their edges. An important sub-set of these structures, and
which are the main concern of this paper, are those essentially of prismatic form but
which can have some transverse stiffening such as is used in box girders, stiffened
plates and plate girders. The analysis of the behavior of these structures is approached
using the finite strip method (FSM). The FSM is based on the eigen-functions, which
are derived from the solution of the beam differential equation of transverse vibration,
and proved to be efficient tool for analyzing a great deal of structures for which both
geometry and material properties can be considered as constants along a main
direction, while only the loading distribution may vary. This method was pioneered
by Cheung [1], who combined the plane elasticity and the Kirchhoff plate theory.
Wang and Dawe [2] have applied the elastic geometrically nonlinear FSM to the large
deflection and post-overall-buckling analysis of diaphragm-supported plate structures.
Also, the FSM is very rapidly increasing in popularity for the analysis of thin-walled
structures. Kwon and Hancock [3] developed the spline FSM to handle local,
distortional and overall buckling modes in post-buckling range. The interaction of
two types of column failure (buckling) in thin-walled structures: local and global
(Euler) column buckling, may generate an unstable coupled mode, rendering the
structure highly imperfection sensitive. The geometrically nonlinear harmonic
coupled finite strip method (HCFSM) [4-5] is also one of the many procedures that
can be applied to analyze the large deflection of thin-walled structures and buckling-
mode interaction. For these problems, only geometrically nonlinear terms such as
square derivatives of transverse displacement w need be included (von Karman
approach). An analysis of the buckling-mode interaction is carried out by the HCFSM
in [6], taking into account the visco-elastic behavior of material.
If uniformly compressed plate or thin-walled structures undergo inelastic
deformation these structures generally include both nonlinearities: the geometrically
nonlinear effects and nonlinear behavior of the material caused by an inelastic
deformation. A mathematical-physical analogy named rheological-dynamical analogy
(RDA) has been proposed in explicit form to predict a range of inelastic and time-
dependent problems related to one-dimensional members, such as buckling, fatigue
etc. [7, 8]. Consequently, the RDA inelastic theory enables the engineer concerned
with materials (for various structural problems) to utilize simple models, expressible
in a mathematically closed-form, to predict the stress-strain behavior. The main
results in the paper [7] are made on the inelastic buckling in the short to intermediate
column range taking into account the governing RDA modulus. However, the wide-
flange column members or thin-walled structures fail as continuum by first
developing local or global buckling modes, which may be changed into plastic
mechanisms and failure. Because of that the two-dimensional (2D) or three
dimensional (3D) analysis must be used.

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The proposed approach combines the RDA and damage mechanics [9] to solve the
nonlinear problem of plate structures under compression using 2D analysis in frame
of the FSM. The one-dimensional RDA modulus is used to obtain one simple
continuous modulus function and a stress-strain curve [10]. When the critical stress
exceeds the limit of elasticity, the first iteration of the modulus provides the Hencky’s
loading function and the von Mises yield stress, whereas the next ones involve the
strain-hardening of the material through visco-plastic flow. At the end of the
iterations a member failure occurs. The key global parameters, such as the creep
coefficient, Poisson’s ratio and damage variable are functionally related. However,
the fact is that cracking is accompanied by an emission of elastic waves which
propagate within the bulk of the material [11]. Because of that, 3D analysis of the
propagation of mechanical waves is used in this paper. The elastic properties of steel
and aluminum determined on test cylinders from longitudinal resonance frequencies
[12], are used in the numerical applications. For the analysis of plate structures using
the FSM, the inelastic isotropic 2D constitutive matrix is derived starting from the
one-dimensional state of stress. Although the quasi-static and dynamic constitutive
relations are derived for isotropic material, different stress components induce
orthotropy in material through the RDA modulus-stress dependence. The nonlinear
term is the stiffness matrix, which depends on inelastic orthotropic constitutive
matrix. Because of that, a new modulus iterative method for the solution of nonlinear
equations is presented. The convergence of the method is fast and gives satisfactorily
accurate solutions in only several iterations as demonstrated in the case of a
rectangular plates [13], and for thin-walled structures in this paper.

2. NUMERICAL APPLICATIONS
The measured and computed elastic parameters for steel and aluminum are shown
in Table 1.

Таble 1- Elastic parameters for steel and aluminum, computed using RDA procedure.
EH (GPa)  φ* ED (GPa) E(0) (GPa)  
Steel 200 0.3 1.502 274.26 265.84 0.116 0.00773
Aluminum 70 0.33 1.940 110.86 102.17 0.179 0.01202

According to the bifurcation form of stability loss, min is scaling factor related to the
critical stress as follows
 (1)
 cr  min
2t
In order to obtain inelastic critical stresses, the Euler formula for buckling of an
isolated plate strip is employed to find the structural-material constant KE of a plate.
For this problem the relative amplitude for the edge local buckling stress is as follows

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 2 EH
2
t
 crE    (2)

12 1   2  b

Consequently, the edge local buckling stress can be represented by

 crE  k crE (3)
where k is the common local buckling coefficient.
Hence, the structural-material constant for the local buckling mode may be
expressed as follows

KE 
*


* 12 1    b 
2 2
 (4)
 
k crE k  2 EH  t 

2.1. Steel structures

The results of buckling behavior of RHS columns investigated in [14] are used in
this paper in order to compare with the proposed method. The results are compared in
Figure 1.

Figure 1 – Quasi-static elastic and inelastic buckling curves for a RHS columns.

The FSM elastic solution with 14 finite strips and 8-35 series terms is in excellent
agreement with the solution that is referred in [14]. The results of both the FSM
visco-plastic and failure (with only 6 or 7 iterations) predictions are obtained using
the long-time modulus EH and . The results are in well agreement with the GBT
deformation theory. Also, the results with initial parameters E(0) and  are in well
agreement with the GBT flow theory. As it is known, stress-strain laws for materials
which exhibit strain-hardening can be divided into two types called theory of plastic
deformation and theory of plastic flow. According to the first, there exists a one-to-
one correspondence between stress and strain in the plastic range. On the other hand,
the theory of plastic flow is based on the assumption that, for a given state of stress,
there exists a one-to-one correspondence between the rates of change of stress and

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strain. Figure 1 shows that RDA failure stresses, which are based on the long-time
modulus of elasticity, are close to the stresses obtained by the GBT deformation
theory. It is logical, because in this case the strain and stress rates are negligible in the
plastic range. Contrary to this, in the case of the short-time excitation, the strain and
stress rates are dominate in the plastic range and the RDA visco-plastic stresses
obtained by the initial parameters are close to the stresses obtained by the GBT flow
theory.
When strain response is described using the harmonic sinusoidal law, the dynamic
parameters are elements of the compliance matrix.
Figure 2 presents the dynamic inelastic buckling curves for relative angular
frequency (RAF) of 1 and 10. All dynamic stresses are below the elastic critical
stresses. The reason for that is the cyclic stress variation in the material under which
the visco-plastic effects like as the viscous damping are developed.

Figure 2 – Dynamic inelastic buckling curves for a RHS columns.

Figure 3. shows only elastic static buckling modes for two lengths of RHS
columns ( 210 mm and 300 mm) with critical sresses of 405.88 MPa and 361.27 MPa,
which are in well agreement with FSM elastic theory.

Figure 3 – Static elastic buckling modes from Abaqus.

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2.2. Aluminum structures

The buckling behavior of aluminum structures was also investigated in [14] using
the GBT formulation for both flow and deformation theories. Figure 4. presents the
results from [14] and from presented method, which are logical if we compared them.

Figure 4 – Static and dynamic inelastic buckling curves for a C-section columns.

3. CONCLUSIONS
Static and dynamic inelastic buckling of thin-walled structures, according to
classical (linear) buckling theory has been the subject of investigation in this paper.
The inelastic FSM is developed through the RDA modeling of materials. Although
the quasi-static 2D constitutive relations are derived for isotropic material, different
stress components induce orthotropy in the material through RDA modulus-stress
depedence. A new modulus iterative method for the solution of nonlinear equation is
applied. The convergence of this method is fast and gives satisfactorily accurate
solutions in only several iterations.

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4. REFERENCES
[1] Cheung, YK. 1976. Finite strip method in structural analysis, Pergamon Press
[2] Wang, S., Dawe, DJ. 1996. Finite strip large deflection and post-overall-buckling
analysis of diaphragm-supported plate structures, Computers and Structures:
61(1):155-170.
[3] Kwon YB, Hancock GJ. 1991. A nonlinear elastic spline finite strip analysis for
thin-walled sections, Thin-Walled Structures:295-319.
[4] Milašinović DD. 1997. The finite strip method in computational mechanics,
Faculties of Civil Engineering: University of Novi Sad, Technical University of
Budapest and University of Belgrade: Subotica, Budapest, Belgrade
[5] Milašinović DD. 2011. Geometric non-linear analysis of thin plate structures
using the harmonic coupled finite strip method, Thin-Walled Structures:
49(2):280-290.
[6] Milašinović DD. 2012. Harmonic coupled finite strip method applied on
buckling-mode interaction analysis of composite thin-walled wide-flange
columns, Thin-Walled Structures:50(1):95-105.
[7] Milašinović DD. 2000. Rheological-dynamical analogy: prediction of buckling
curves of columns, International Journal of Solids and Structures:37(29):3965-
4004.
[8] Milašinović DD. 2003. Rheological-dynamical analogy: modeling of fatigue
behavior, International Journal of Solids and Structures:40(1):181-217.
[9] Lemaitre J. 1984. How to Use Damage Mechanics, Nuclear Engineering and
Design:80:233-245.
[10] Milašinović DD. 2015. Rheological-dynamical continuum damage model for
concrete under uniaxial compression and its experimental verification,
Theoretical and Applied Mechanics:42(2):73-110.
[11] Carpinteri A, Lacidogna G, Pugno N. 2007. Structural damage diagnosis and
life-time assessment by acoustic emission monitoring, Engineering Fracture
Mechanics:74(1-2):273-289.
[12] Subramaniam VK, Popovics JS, Surendra PS. 2000. Determining elastic
properties of concrete using vibrational resonance frequencies of standard test
cylinders, Cement, Concrete, and Aggregates, CCAGDP:22(2):81-89.
[13] Milašinović DD, Majstorović D, Došenović M. 2015. Quasi-Static and Dynamic
Inelastic Buckling and Failure of Plates Structures using the Finite Strip
Method, In: Kruis, J. Tsompanakis, Y. and Topping, B.H.V. (Editors),
Proceedings of the Fifteenth International Conference on Civil, Structural and
Environmental Engineering Computing. Civil-Comp Press, Stirlingshire, UK,
Paper 100, doi: 10.4203/ccp.108.100.
[14] Gonçalves R, Camotim D. 2004. GBT local and global buckling analysis of
aluminum and stainless steel columns, Computer and Structures: 82:1473-1484.

[73]
 SCIENTIFIC CONFERENCE
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UDK: 624.041
Branislava NOVAKOVIC

STABILITY OF A BEAM CLAMPED ON ONE END AND

ELASTICALLY RESTRAINED-CLAMPED ON THE OTHER END
Abstract: We consider the problem of determining the stability of an elastic beam positioned on Winkler
type of elastic foundation. The beam is loaded by a compressed axial force of arbitrary intensity. The
characteristic equation that determining critical loads for the beam is derived. By using the nonlinear
system of equations we determine the post-critical behavior of the beam. It is shown that there are sub-
critical buckling modes and buckling modes that do not bifurcate from the trivial state.

Кey words: stability, elastic foundation, critical load, post-critical behavior

STABILNOST ŠTAPA UKLEŠTENOG NA JEDNOM KRAJU I

ELASTICNO OGRANIČENOG-UKLEŠTENOG NA DRUGOM

Rezime: Razmatran je problem stabilnosti elastičnog štapa koji se nalazi na elastičnoj podlozi
Vinklerovog tipa. Štap je opterećen aksijalnom silom pritiska proizvoljnog intenziteta. Izvedena je
karakteristična jednačina štapa koja je potrebna za određivanje kritičnog opterećenja. Korišćenjem
neinearnog sistema jednačina određeno je poslekritično ponašanje štapa. Pokazano je da postoje sub-
kritični modovi izvijanja i modovi koji ne polaze od tačaka bifurkacije trivijalnog rešenja.

Ključne reči: stabilnost, elastična podloga, kritično opterećenje, poslekritično ponašanje

Assoc. Prof. PhD, University of Novi Sad, Faculty of Technical Sciences, Trg D. Obradovica 6, nbrana@uns.ac.rs

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1. INTRODUCTION
The beam on an elastic foundation is a structure which has many applications in
technical practice including civil engineering, aerospace engineering etc. The problem
of stability was solved by Timoshenko [1]. Stability analysis of beam on elastic
foundation of Winkler type was presented by Atanackovic [2]. The critical force for a
beam immersed in an elastic medium was determined by Teodorescu [3]. Jin and Bao
[4] derived the sufficient conditions for stability of Euler elasticas. They concluded
that the straight shape of the beam can be stable or unstable depending on the value of
the load. The stability and behavior of a cantilevered beam with tip mass, subjected to
a distributed follower force positioned on elastic foundation was analyzed by Kim at
al. [5]. The secondary post-buckling of an elastic column with spring supports of equal
stiffness of extensional type at both clamped ends is studied by Wu in [6].

2. MATHEMATICAL FORMULATION
Consider an elastic beam of length L loaded by an axial force F with the action
line coinciding with the x axis of a rectangular coordinate system x-B-y (see Figure
1.). The beam is positioned on a Winkler type of foundation has one clamped end and
the other elastically supported end. We use the following notation: H and V are
components of the contact force (i.e. the resultant force in an arbitrary cross-section)
along x and y axes, respectively, M is the bending moment, θ is the angle between the
tangent to the column axis and the x axis, S is the arc-length of the column axis
measured from the origin of the coordinate system B, E is the modulus of elasticity.

L
EI F
B
x
C

y
Figure 1. Coordinate system and load configuration

Also we assume that the beam has a variable cross sectional area A  A(S ) and the
axial moment of inertia I and the cross-sectional area A are connected as I=nAn
where n is a constant that depends of n and n =1, 2, 3. The governing equations:
equilibrium equations, geometrical and constitutive relations (see [2]) are
dH dV dM
 0,  q y ,  V cos  H sin  ,
dS dS dS
(1)
dx dy d
 cos ,  sin  , M  EI .
dS dS dS

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where qy=-y and >0 is a constant stiffness of the foundation. Boundary conditions
are
y  0   0,   0   0,  ( L)  0, V ( L)  cy  L  , H ( L)  F , (2)
where c is a spring constant of the support.
By introducing the dimensionless quantities
S A x y W c
t , a 2 ,   ,   , w 3 , b ,
L L L L L  n EL2 n 3
(3)
 F V M
1  2n4
, 2  2n2
, v 2n2
, m ,
 n EL  n EL  n EL  n EL2 n 1
we obtain
m
v  
1 , m  v cos  2 sin  ,   cos ,   sin  ,   , (4)
an
subject to
  0   0,  (0)  0,  (1)  0, v  1   b  1  , (5)

where    d   .
dt
The trivial solution for the system (4), (5) in which the axis of the rod remains
straight for any value of the dimensionless parameters 1 , 2 is

 0  t , 0  0  v0  0. (6)
To examine stability of the trivial configuration defined by (6) we use Euler
method. In order to obtain nontrivial solution and determine (1,2)R2 for it we
assume    0   ,   0   ,.... where  ,  ,.... are perturbation. After
substituting this in (4) and (5), neglecting the higher order terms in perturbations and
omitting  in front of variables we get
m
v  
1 , m  v  2 ,   0,    ,   , (7)
an

subject to (5) where    d   .
dt

3. CRITICAL VALUES OF LOAD PARAMETERS

The goal of this section is determining the critical loads (1, 2) of the beam for
which there is more than one solution of the system (4), (5). A necessary condition
that (4), (5) has a nontrivial solution is that linearized system (7), (5) has a nontrivial
solution. In the special case when a = const = 1 the Eqs. (7) become

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v  
1 , m  v  2 ,   0,    ,   m, (8)
The system (8) can be reduced, so we have
....
  2  
1  0 (9)
Characteristic equation of (9) is
r 4  2 r 2  1r  0 (10)
The roots of the Eq. (10) are
r1  i1 , r2  i1 , r3  i2 , r4  i2 , (11)
Where
1 1
   2 2  41  2  2  2 2  41  2
1   2  , 2    . (12)
 2   2 
Then the solution of (10) is
  C1 cos  1   C2 sin  1   C3 cos  2   C4 sin  2  , (13)
where Ck, k=1,2,3,4 are arbitrary constant. The boundary conditions subjected to (10)
are
  0   0,  (0)  0,  (1)  0,   1   b  1   2  1   0. (14)
By using boundary conditions (14) we have the following condition for the
existence of non-trivial solution
21 2b   14  2  12  23  sin 1 cos  2   1 2 4  13  2 2  sin  2 cos 1 
(15)
 12  22  b sin 1 sin 2  212b cos 1 cos 2  0.
The necessary condition for the existence of solutions of the Eq. (15) is
22  41  0. (16)

4. NUMERICAL RESULTS
We determine the critical (smallest positive root of (15)) value of the foundation
stiffness parameter from (15) for several values of and b=500 as shown in Table 1.

Таble 1- Critical values of for different values of axial force and parameter b=500
b 500 500 
 147.426136 390.794383 941.006943
 50 65 100

We determine the critical value of the foundation stiffness parameter from (15) for
several values of b and =62 as shown in Table 2.

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Таble 2- Critical values of for different values of b and parameter =62

b 250 500 
 375.945773 338.848043 321.651493
 62 62 62

For the beam clamped on the both end (without elastic support, b is infinity) and
=62 critical value of 1= 305.821889.
The post-buckling shapes for = 338.848043, =63 and b=500 are shown in
Figure 2.

Figure 2. Post-buckling modes for the case 1  338.848043, 2  63, b = 500

The post-buckling shapes of first modes for = 338.848043, =61, b=350 and
b=500 are shown in Figure 3.

Figure 3. Post-buckling modes for the case 1  338.848043, 2  61, b=350 and
b=500

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From Fig. 3, it can be concluded that as the parameter b increases, the amplitude
of the first buckling mode increases as well. For b=350 the amplitude
max=0.069632492, for b=500 the amplitude max=0.1875903638

5. CONCLUSIONS
We analyzed the stability for an elastic beam on elastic foundation which is
clamped on one end and elastically supported-clamped on the other. The
characteristic equation that determining critical loads for the beam with unit cross-
section is derived.
By using the characteristic equation we determined the critical load (lowest
value) of 1 for several values of parameters 2 and b. The value of the foundation
stiffness increases as the value of axial force increases for the constant value of spring
constant b. Also, by increasing spring constant b for the constant value of axial force
we have decreasing of the value of the foundation stiffness.
We studied the post-critical behaviour of the beam. The sub-critical buckling
modes for chosen value of parameters are determined. We obtained buckling modes
that do not bifurcate from the trivial state.
The stability of the buckling modes must be analysed separately. This work is in
progress now.

ACKNOWLEDGMENT.
Funding for this work was partially provided by the Faculty of Technical
Sciences of the University of Novi Sad, Project No2015-054.

REFERENCES.
[1] Timoshenko, S. P. 1961. Theory of elastic stability. Mc Graw-Hill, New York
[2] Atanackovic, T. M. 1997 Stability Theory of Elastic Rods. World Scientific,
River Edge, New Jersey
[3] Teodorecsu, P. 1981. On the buckling of a column in an elastic medium.
International Journal of Engineering Sciences 19: 1749-1755.
[4] Jin, M., Bao, Z. B. 2008. Sufficient condition for stability of Euler elasticas.
Mechanics Research Comminications 35: 193-200.
[5] Kim, J. O., Lee, K. S., Lee, J. W. 2008. Beam stability on an elastic foundation
subjected to distributed follower force. Journal of Mechanical Science and
Tehnology 22: 2386-2392.
[6] Wu, B. 1998. Secondary buckling of an elastic column with spring-supports at
clamped ends. Archive of Applied Mechanics 68: 342-351.

[79]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Doncho PARTOV
Vesselin KANTCHEV2

COMPARATIVE ANALYSIS BETWEEN (AAEM) METHOD OF

BAŽANT AND INTEGRAL EQUATION OF VOLTERRA IN
INVESTIGATION OF STEEL-CONCRETE BEAM REGARDING
CREEP OF CONCRETE
Abstract: The paper presents comparative analysis of the results connected with the stress-
strain changes in statically determinate composite steel-concrete beam, obtained by AAEM
method of Bažant and integral equation of Volterra, due to creep according EC2. The
closeness of the results obtained by the two methods is shown with an example from the
bridge practice.

Кey words: steel-concrete section, integral equations, rheology, Gardner&Lockman model.

KOMPARATIVNA ANALIZA (AAEM) METODE BAŽANTA I

INTEGRALNIH JEDNAČINA VOLTERA U ANALIZI SPREGNUTE
GREDE ČELIK-BETON SA ASPEKTA TEČENJA BETONA
Rezime: U radu je prikazana uporedna analiza rezultata povezanih s promenama napon-deformacija
statički određene grede spregnutog preseka čelik-beton usled tečenja betona prema EC2, dobijenih
AAEM metodom Bažanta i integralne jednačine Voltera. Sličnost rezultata dobijenih dvema metodama
prikazana je na praktičnom primeru mosta.

Ključne reči: Ortotropna ploča, građevinske metode, bugarsko nasleđe - mostovi

1
Prof. PhD.,Univ. of Struct. Eng. and Arch., 1373 Sofia, 175 Suhodolska Str., e-mail:partov@vsu.bg
2
Assoc. Prof. PhD., Univ. of Struct. Eng. and Arch., 1373 Sofia, 175 Suhodolska Str., e-mail:kantchev@vsu.bg

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1. INTRODUCTION
The time-varying behaviour of composite steel-concrete members under sustained
service loads drawn the attention of engineers who were dealing with the problems of
their design more than 60 years[3,4,5]. The solution of structural problems involving
creep and shrinkage phenomena in composite steel-concrete beams has been an
important task for engineers since the first formulation of the mathematical model of
linear viscoelasticity. If on one hand the definition of a suitable formulation of creep
laws involved scientists and researchers in past decades and many prediction models
have been developed, starting from experimental data and from the direct observation
of the long term behaviour of concrete structures, the development of structural
analysis procedures, based on the creep models, is on the other hand, of great interest
for engineers who need to investigate the effects of creep and shrinkage on the
structures they design. In general, time-dependent deformation of concrete may
severely affect the serviceability, durability and stability of structures[5,16].

2. ABOUT SOME METHODS FOR TIME-DEPENDENT ANALYSIS OF

COMPOSITE STEEL-CONCRETE BEAMS REGARDING RHEOLOGY
WITH ACCENT OF AAEM METHOD
2.1. Common considerations
The first works, which give the answer to this problem are based on the Law of
Glanville(1933) –Dischinger(1937,1939) - theory of aging[6], or also called the rate
- of - creep methods, which first formulated a time-dependent stress-strain
differential relationship for concrete. Its refinement is known as the improved
“Dischinger theory of aging” was proposed from Rüsch-Jungwirth-
Hilsdorf(1973)[15]. Many books and papers connected with the Law of Dischinger
and improved “Dischinger theory of aging” represent one independent group for
which it is characteristic, that by writing equilibrium and compatibility equations and
the constitutive laws for the two materials, the problem is governed by a system of
two simultaneous differential equations, which have been derived and solved.
Another scientific works which give the answer to this problem used the theory of
Maslov(1940)[9] - Arutyunyan(1952)[3] –Prokopovich-(1963)[13]-
Aleksandrovskii(1966)[2]. This theory is obviously much more complicated than the
„theory of aging”, but the theory of aging, is substantially more complicated than the
effective modulus method(EMM), described with: Eeff  1/ J (t , )  E ( ) /1   (t , ) .
For the designers of the composite steel-concrete construction, is better to know
that this method is exact only if the loads and stresses in a structure have a single-
step history, which means that they are constant from the moment of first loading.
This fact is more far from true, in internally statically indeterminate system with
significant stress redistributions induced by creep or shrinkage, as in the case of
composite steel-concrete construction. Further development of rheology as a
fundamental science and its application to concrete as well as a great number of

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investigations in the field of creep of concrete have led to new formulations of the
time-dependent behavior of concrete. These new formulations giving the relationship
between  c t  and  c t  are formulated by integral equations, which present the
basis of the theory of linear viscoelastic bodies. The integral-type creep law, i.e., the
superposition equation for uniaxial prescribed stress history  t  , is expressed by:

d  
t
 c t ,t0    sh t    t0 J t ,t0    J t , d . (1)
t0
d
Since the solutions of structural creep problems with realistic compliance function
, such as in ACI209R-92, EC2, G&L models and B3 for creep of concrete provisions
cannot be performed analytically and require a deep knowledge in the higher level of
mathematics theory( integral equations of Volterra, numerical solutions of such of
type equations, using formulae of quadratures - such as: trapecoidal rules, Simpson,
Chebyshov, Gaus, Euler-Gregory –Macloren), simplified approximate methods have
been favoured by designers.

2.2. Formulation of the age-adjusted effective modulus method

However, in order to avoid the mathematical problems in solving of the
integral equations of Volterra for treating the problem connected with the creep of
concrete structures, it has been revised the integral relationship into new algebraic
stress-strain relationship :
 c0
 ct  1   t    ct   c0 1  t  , (2)
Ec 0 Ec 0
where  is the relaxation coefficient known from Trost-Zerna works[14,17].
When more extensive test date and data of long duration became available and were
systematically analysed from Bažant[4,8], it turned out that the afore-mentioned
theory leading to differential equations are overall not more accurate than the
effective modulus methods(Partov and Kantchev[10,11,12]), which leads to algebraic
linear equations with respect to time t. According Bažant and Jirasek[8] none of them
is sufficiently accurate compared to the computer solutions for e realistic (un -
simplified) compliance function based on long – time –measurements with a broad
range of ages at loading. A remedy that is sufficiently accurate in most basic
situations we can found in the age-adjusted effective modulus method, proposed and
mathematically proven by Bažant[8], as a modification and refinement of the
relaxation method, semi-empirically developed by Trost[14,17]. The age-adjusted
effective modulus (AAEM) method is formulated for a one-step loading history. By
using algebraic approach a new simpler forms for (1) are obtained from Bažant[8].
His methods are based on the hypothesis that the strain in the concrete fibers can be
considered as a linear function of the creep coefficient. This permits transforming (1)
in to (3):

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 1   t , t0  
 c  t , t0    sh  t    c  t0    28 
E 
 c 0t  E c 28 
(3)
 1   t , t0  28  t , t0  
  c  t    c  t0     
 Ec  t0  Ec 28 
Ec  t0  Ec 28
where:   t , t0    ; (4)
Ec  t0   R  t , t0  Ec  t0  28  t , t0 
is the aging coefficient;  t , t0  - the creep coefficient ; Rt , t0  - relaxation
function, i.e., the stress response to a constant unit strain applied at the time t 0 ; Ec -
the elastic modulus of concrete at 28 days.
0,992 0,115  J (t  , t1 )  t  t1
R(t , t1 )     1 ;   ; (5)
J (t , t1 ) J (t , t  1)  J (t , t1  )  2
The same expression was derived using another approach from Folich in 2012[7].
The AAEM methods is frequently adopted for the basic investigation of stress
redistribution in non-homogenous cross-section, like prestressed concrete section with
prestressing and reinforcing steel in one or multiple layers, and steel-concrete
composite section. In the papers [10,11] using the mathematical model in fig.1, the
authors introduce the system of linear Volterra integral equation of second kind and
obtain the results from their numerical solutions. The kernels of the integral equations
contain the respective creep functions corresponding to the model EC2 [1].

Nc ,r ( t ) N c ,o

M c ,r t  M c ,o

M0 
 1237,00kNm

N s ,r ( t ) N s ,o
M s ,r ( t ) M s ,0

Fig. 1 Mathematical model Fig. 2. Composite beam

3. BASIC ASSUMPTION AND MATERIAL CONSTITUTIVE

RELATIONSHIP
The hypotheses in the elastic analysis of composite steel-concrete sections
with stiff (rigid) shear connectors are comment in [10,11,12]. In the range of
service ability loads concrete behaves in a way allowing to be treated as a
linear viscoelastic body. Then the stress-strain behavior of concrete can be

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described with sufficient accuracy by the integral equations (1) by Bolztmann-

Volterra:
 t  t
d   1
 c  t   c 0 1    t  t0    c 1    t    d ;
d Ec   
(6),
Ec  t0  t0

Where, according EC2: the creep (compliance) function proposed by the 1990
CEB Model Code (“CEB-FIP”1991) is given by the
 t , t0 
relationship: J t , t0   , where  t ,t0  = the creep coefficient; and
1

Ec t0  Ec
Ec t0  and Ec = modulus of elasticity at the age of t 0 and 28 days, respectively. The
creep coefficient is evaluated with the following formula:
1  RH /100
 t , t0   RH   f cm  t0  c t  t0  where RH  1 - is a factor to
0.46  h0 /100 
0.33

allow for the effect of relative humidity on the notional creep coefficient. RH is the
5.3
relative humidity of the ambient environment in % .   f cm   - is a
 fcm /10 
0.5

factor to allow for the effect of concrete strength on the notional creep coefficient.
 t0  
1
- is a factor to allow for the effect of concrete age at loading on
0.1  t0 
0.2

the notional creep coefficient (for continuous process we consider the function).
   
1
is a function of aging, depending on the age of concrete and it
0.1   
0.2

0.3
 t  t0 
characterizes the process of aging.  c t  t0     is a function to
  H  t  t0 
describe the development of creep with time after loading.
   h0
RH 
18

 H  1501  1.2    250  1,500 coefficient depending on the relative

  100 
 100
humidity (RH in %) and notional member size ( h0 in mm), where f cm  f ck  8 
the mean compressive strength of concrete at the age of 28 days (megapascals); and
2 Ac
h0   the notional size of member (millimeters) ( Ac = the cross section; and u
u
= the perimeter of member in contact with the atmosphere). Constant Young’s
modulus is given by Ec  10 4  f cm 3 . Variable Young’s modulus is given
1

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by: Ec t    cc0.5 Ec , where Ec  10 4  f cm 3 and cc  exp  s 1  5.3/ t 0.5  , where s =

1

 
0.25 for normal and rapid hardening cements.
  5.3  
0.5  0.25 1 
So Ec t   336190e   t 
, 0  RH   f cm  t0  is a final creep coefficient.
 t    RH   f cm    c t      N k   f t    , where k       and
f t      c t    . The function  c t    - (where t is the time interval during
which the structure is under observation,  is the running coordinate of time) –
characterizes the process of creeping. The creep (compliance) function proposed by
the EC2, is composed of the elastic and creep strains.The elastic strain is reciprocal of
the modulus of elasticity at the age of loading Ec t0  and the creep strain is the 28
day creep coefficient 28 (t , t0 ) devided by the modulus of elasticity at 28 days
( Ecm28 ).The creep coefficient 28 (t , t0 ) is the ratio of the creep strain to the elastic
strain due to the load applied at the age of 28 days.

4. BASIC EQUATION OF EQUILIBRIUM

Let us denote both the normal forces and the bending moments in the cross-section
of the plate and the girder after the loading in the time t = 0 with N c ,0 , M c ,0 , N a , 0 ,
M a, 0 and with N c ,r t  , M c ,r t  , N a,r t  , M a,r t  a new group of normal forces
and bending moments, arising due to creep and shrinkage of concrete. For a
Ac nI c n
composite bridge girder with J c   0.2 according to the suggestion of
As I s
(Sonntag 1951) we can write the equilibrium conditions in time t as follows
N t   0; N c,r t   N a,r t  ; (7)
 M t   0; M c , r  t   Nc , r  t  r  M a , r  t  ; (8)
Due to the fact that the problem is a twice internally statically indeterminate
system, the equilibrium equations (7), (8) are not sufficient to solve it. It is
necessary to produce two additional equations in the sense of compatibility of
deformations of both steel girder and concrete slab in time t (fig. 1).

5. DERIVING OF THE GENERALISED MECHANIC-MATHEMATICAL

MODEL USING INTEGRAL EQUATION OF VOLTERRA ACCORDING
EC2
Using strain- compatibility on the contact surfaces between the concrete and the steel
members and compatibility of curvature when   t for constant elasticity module

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of concrete for assessment of normal forces N c ,r t  and bending moment M c ,r t 

two linear integral Volterra equations(9-10) of the second kind are derived[10]:
t
N c ,r t    N  N c ,r  
d
1   RH   f cm    t   d  N N c,0 RH   f cm  t0  c t  t0   (9)
t0
d
  N N sh  c t  t 0 ;
t
M c ,r t   M  M c ,r  
d
1   RH   f cm    c t   d  M M c,0 RH   f cm  t0  c t  t 0  
t0
d (10)
Ec I c
 M N c ,r t r;
Ea I a

6. DERIVING OF THE GENERALISED MECHANIC-MATHEMATICAL

MODEL USING ALGEBRAIC INTEGRAL EQUATION OF VOLTERRA
ACCORDING AAEM METHODS OF BAŽANT
Using the above mentioned approach, for constant elasticity module of concrete
for assessment of normal forces N c  t  and bending moment M c  t  two algebraic
expressions are derived:
N (t ) (t , t0 ) N c (t0 ) (t , t0 )N ;
Nc (t )  1 c 0  (11)
N   (t , ) (t , )  1   (t , ) (t , )N 
M c (t0 ) (t , t0 ) N c (t )r Ec J c
M c (t )   1
   (t , ) (t , )  M   (t , ) (t , )  Ea J a
1
M (12)
M c (t0 ) (t , t0 )M N c (t )rM Ec J c
 
1   (t ,  ) (t ,  ) M  1   (t ,  ) (t ,  ) M Ea Ja

7. NUMERICAL EXAMPLE
The two methods presented in the previous paragraph is now applied to a simply
supported beam, subjected to a uniform load, whose cross section is shown in fig. 2.
The following parameters are chosen according EC2 model.
Ea
Ec  3,2.10 4 MPa , Ea  2,1.105 MPa , Ac  8820 cm 2 , Aa  383,25 cm 2 , n   6,56
Ec
I c  661500 cm 4 , I a  1217963,7 cm 4 , rc  23,039 cm, ra  80,829 cm, r  103,868 cm,
Ai  2453,05 cm 2 , I i  4536360,758 cm 4 .M 0  1237 kNm, N c ,o  846,60 kN , M c ,o  27,56 kNm
1 1
 E A  A r2   EI 
M a ,o  330,13kNm, N  1  c c 1  a   0,060545358, M  1  c c   0,922950026
 Ea Aa  Ia   E a Ia 

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 t0  
1
  f cm  
5.3
 3.06  0,4223
0.1  t0 
0.2
( f cm / 10) 0.5 f cm 30 t0  60

h0  2 AC / u  300 mm ;  H  150 1  1.2*80 /100   h0 /100  250  915,82  1500 ;

18

 

RH  1 
1  RH /100
 1,30146 ; 0  RH   f cm  t0  =1,6817;
0.46 3
 h0 /100  RH 80, h 300
0

 c 36500  60  0,9925811 ; t 36500  0  c 36500  60  1,669242 ;

7.1. Numerical solution using integral equation of Volterra

In fig. 3 and 4a,b it is shown the values of normal forces and bending
moments in time t. A numerical method for time-dependent analysis of composite
steel-concrete sections according EC2, ACI 209R-92 and G&L models is develop
using MATLAB code and numerical algorithm which was successfully applied to a
simple supported beam. These numerical procedures, suited to a PC, are employed to
better understand the influence of the creep of the concrete in time-dependent
behaviour of composite section. For a good accuracy of the time values, the numerical
results are presented on logarithmic time scales. The choice of the length of time
step of the proposed numerical algorithm is based on numerous numerical
experiments with different steps (seven, three and one days). So we conclude that
good results can be achieved from practical point of view with one day step. For our
purpose we consider a period of about 33-35 years. For the service load analysis, the
proposed numerical method makes it possible to follow with great precision the
migration of the stresses from the concrete slab to the steel beam, which occurs
gradually during the time as a result of the creep of the concrete.

a) b)
Fig. 3. Normal forces Fig. 4a,b. Bending moments: M c ,r (t ) and M a ,r (t ) in
Nc,r  t   Na ,r (t ) time in
t  12060 days
time t  12060 days

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7.2. Prediction of Concrete creep effect Using AAEM

Let,s consider the next following initial data: t0  60 days; t  12060 days;
Ec (t0 )  32000MPa ;
The creep coefficient:
0,3
1  t  t0  12060  60 
  t  12060, t0  60   RH   f cm    t0   c  t  t0   1,30146.3, 06.   
0,1  (t0  60)0,2   H  (t  t0 )  12915,82 
 1,30146.3, 06.0, 4223.0,97817747  1, 645095488
1   (t , t0 ) 1  1,145095488
J (t  12060, t0  60)    0, 0000826059 ;
Ecmt0 32000
0,3
1  t  t0  12060  12059  1 
 (t , t0  (t  1))  (12060,12059)  1,30146.3.06   
0,1  (12059)0,2   H  (t  t0 )  915,82  1 
 1,30146.3, 06.0,150368792.0,129215548  0, 079087302;
1   (t , t  1) 1  0, 079087302
J (t  12060, t  1  12059)    0, 000033721 ;
Ecmt0 32000
t  t1 12060  60
   6000 ;
2 2
0,3
1  t  t0  6000 
 (t  , t1 )   (12060  6000, 60)   (6060, 60)  1,30146.3, 06.  915,82  6000  
0,1  600,2  
 1, 611666145.3, 06.0.422309218.0,958279661  1, 611666145;
1   (t  , t1 ) 1  1, 611666145
J (t  , t1 )    0, 000081614 ;
Ecmt0 32000

 (t , t1  )   (t  12060, t1  6060) =
0,3
1 12060  6060  6000 
= 1,30146.3.06.  0, 657063792 ;
0,1  6060  915,82  6000 
0,2 

1   (t , t1  ) 1  1, 657063792
J (t , t1  )    0, 000051783 ;
Et0 32000
Rt , t0  - relaxation function:
0,992 0,115  J (t  , t1 ) 
R(t , t0 )     1 
J (t , t0 ) J (t , t  1)  J (t , t1  ) 
0,992 0,115  0, 000081614 
  1  10036, 49555
0, 000082659 0, 000033721  0, 000051783 

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The aging coefficient:

E (t0 ) 1 32000 1
 (t , t0 )   (12060, 60)      0,849094942
E (t0 )  R(t , t0 )  (t , t0 ) 32000  10036, 49555 1, 645095488
Then: :
Nc (t , t0 ). (t , t0 ).N 84660.1, 645095488.0, 060545358
Nc (t )    7774, 752314daN
1   (t , t0 ). (t , t0 )N 1  0,849094942.1, 645095488.0, 060545358
(according AAEM).
Calculating M c (t ) using the formulae:
Ec I c
N c (t ).r.M
M c (t0 ). (t , t0 ).M Ea I a
M c (t )   
1   (t , t0 ). (t , t0 )M 1   (t , t0 ). (t , t0 ).M
2756.1, 645095488.0, 0922950026 7774, 75.1, 0387.0,922950026.0, 082760998
 
1  0,849094942.1, 645095488.0, 0922950026 1  0,849094942.1, 645095488.0,922950026
 1827,939487  269, 459628  1558, 479859 daNm.

Calculating M a (t ) using the formulae:

M a (t )  M c (t )  Nc (t ).r  1558, 479859  7777,75.1,0387  9634,112684 daNm.
Comparisons between the results obtained from the numerical solution and AAEM
methods are as follows N c (t ) =7774,752314 daN (by ААЕМ) and N c (t ) =7660,20
daN (by numerical method); (  =1,495%). M c (t ) =1558,4798596 daNm (by ААЕМ)
and M c (t ) = 1520,60 daNm (by numerical method) (  =2,49%). M a (t ) =
9634,112684 daNm (by ААЕМ) and M a (t ) = 9477,24 daNm (by numerical method).
(  =1,65%).

8. CONCLUSION
The age-adjusted effective modulus method must to know that is development to
be theoretically exact for any creep function deriving in EC2, ACI209R-92 and G&L
model. In our case to solve the creep problem in the composite steel-concrete beams,
we used the EC2 model for describing the creep evaluation. The results obtained by
the AAEM method of Bažant are completely comparable with the results based on
numerical method according to the EC2 provision.

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REFERENCES
[1] ACI 209.2R-08, Guide for Modeling and Calculation of Shrinkage and Creep in
Hardened Concrete, American Concrete Institute, ACI 209.2R-08, ACI, (2008),
48 pp.
[2] Alexandrovskii S. V. (1966), Analysis of Plain and Reinforced Concrete
Structures for Temperature and Moisture Effects (with Account of Creep) (in
Russian), Stroyizdat, Moscow, (1966), pp 443.
[3] Arutyunian N. Kh., Some Problems in the Theory of Creep (in Russian),
Techteroizdat, Moscow, (1952) (French transl., Eyrolles 1957, English transl.,
Pergamon Press 1966), pp 319.
[4] [14] Bažant Ž. P., Editor , Mathematical Modeling of Creep and Shrinkage of
Concrete, John Wiley & Sons, (1988), pp 459.
[5] Chiorino, M. A., An Internationally harmonized Format for Time dependent
Analysis of Concrete Structures, Proceedings IABSE-FIP Conference
Dubrovnik,(2010), Vol.1, pp.473-480.
[6] Dischinger F., Untersuchungen über die Knicksichereit, die Elastische
Verformung und das Kriechen des Betons bei Bogenbrücken, Der Bauingenieur,
Vol.18, (1937), pp. 487-520, 539-52, 595-621.
[7] Emra,B., Folic, R., Another approach to calculation of concrete age coefficients,
Proceedings- Scientific Conference INDIS, november, 2012, Novi SAD, pp.33-
38.
[8] Jirasek M. and Bažant Z.P. (2002), Inelastic Analysis of Structures, J.Wiley &
Sons, (2002), 734 pp.
[9] Maslov G. N., Thermal Stress States in Concrete Masses, with Account of
Concrete Creep (in Russian), Izvestia NIIG, 28, (1941), pp 175-188.
[10] Partov, D., Kantchev, V., „Time-dependent analysis of composite steel-concrete
beams using integral equation of volterra, according EUROCODE-4“,
Engineering MECHANICS, Vol. 16, 2009, No 5, pp 367-392.
[11] Partov, D., Kantchev, V., „Level of creep sensitivity in composite s steel-
concrete beams, according to ACI 209R-92 model, comparison with
EUROCODE-4(CEB MC90-99)“, Engineering MECHANICS, Vol. 18, 2011,
No 2, pp 91-116.
[12] Partov,D., Kantchev V., “Gardner and Lockman model (2000) in Creep analysis
of composite steel-concrete section “, ACI Structural Journal, Vol.111, No.
1(January-February), 2014, pp 59-69.
[13] Prokopovich I. E. Fundamental study on application of linear theory of creep, (In
Russian),Vyssha shkola, Kiev, (1978), 143 pp.
[14] Trost, H. (1967), Auswirkungen des Superpositionsprinzips auf Kriech- und
Relaxationsprobleme bei Beton und Spannbeton, Beton-und Stahlbetonbau, Vol.
62, (1967), No. 10, pp. 230-238; No. 11, pp. 261-269.

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[15] Rüsch H. and Jungwirth, D., Berücksichtigung der Einflüsse von Kriechen und
Schwinden des Betons auf das Verhalten der Tragwerke, Werner Verlag, (1976),
Düsseldorf.
[16] Šmerda, Z., Křistek, V., Creep and Shrinkage of Concrete Elements and
Structures, Elsevier, Amsterdam- Oxford- New York – Tokyo (1988), pp 296.
[17] Zerna W., Trost H.: Rheologische Beschreibung des Werkstoffes Beton, Beton
und Stahlbetonbau, Vol. 62, H.7, (1967), pp. 165–170.

[91]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Doncho PARTOV
Chavdar STOYANOV2
Milen PETKOV3

COMPUTATIONAL ANALYSIS OF THE TIMBER ROOF

CONSTRUCTION OF THE CHURCH ST. DIMITAR IN KUSTENDIL
Abstract: Based on computational analysis and detailed visual inspection results, scope and general
methods of works construction ensuring adequate rigidity and load capacity of the structure were
determined Calculations of spatial superstructure frame have been made with the use of Tower program.

Кey words: timber structure; computational analysis; excessive deformations, wooden skeleton..

PRORAČUNSKA ANALIZA DRVENE KROVNE KONSTRUKCIJE

CRKVE SV. DIMITAR U KUSTENDILU
Rezime: Na osnovu proračunske analize i rezultata detaljnog vizuelnog pregleda, određen je obim i opšte
metode gradnje koji obezbeđuju adekvatnu krutost i nosivost konstrukcije. Proračun prostornog rama
izvršen je u programskom paketu Tower.

Ključne reči: drvena konstrukcija, kompjuterska analiza, prekomerne deformacije, drveni skelet

1
Prof. D. N. Partov, PhD, 1373 Sofia, Suhodolska Str.175, Univ. Str. Eng. and Arch., partov@vsu.bg
2
Mag. Chavdar Stoyanov, 1373 Sofia, Suhodolska Str.175,Univ. Str. Eng. and Arch., ing4040@abv.bg
3
Assist. Milen Petkov,1373 Sofia,Suhodolska Str.175,Univ.Str.Eng.and Arch., milenspetkov@abv.bg

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1. INTRODUCTION
1.1. General description of the structures of the Church St. Dimitar in Kustendil
Church "St. Martyr Dimitar" is a Bulgarian Revival church located in the eastern
part of Kyustendil[4]. It was built between the 1864th and 1865thh, but the year 1866
for the completion of the temple is considered the most reliable. The church is
rectangular in plan dimensions: width 15,60m and 26,65m length(Fig.1.1.1). The bell
tower of the church was created and added after the liberation in 1876. The whole
church with bell tower is high about 12 meters.

Fig.1.1.1 - Cross Section and Outside View on the Church “St. Dimitar”

The roof structure of the church is made entirely of wood elements. Inside the
church are constructed by two rows of wooden columns, passing through the arch of
the roof structure and reaching the inclined beams of the roof of the building. On the
columns at the level of the floor - ceiling beams and above the level of the roof,
longitudinal beams are situated, bearing by both sides respectively the weight of other
parts of the roof structure. The main structural elements in it - wooden columns, are
located at the intersection of letter and number of axles of the church. On the level of
the top of the stone walls have developed two uninhabited galleries with wooden floor
beams(fig.1.1.2a). At one end floor beams rely on the stone walls of axes A and
G(fig.1.1.2b). The inner end of the beams are based on the main longitudinal beam,
which in turn is supported on wooden columns(fig.1.1.2c). Above this elevation

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wooden columns continue up to a height of 1,96 m. Above the galleries columns are
united with one purlin, which lies on them in the distances marked in digital axes.
Purlin rests on columns by pillow(fig.1.1.2c). The slope of the roof (320) is formed
with inclined ribs which lie in the lower end on the stone walls.

a) b) c)
Fig.1.1.2 a,b,c - View on the wooden galleries, connections between floor and roof beams in
axis A and axis G, main longitudinal beam on wooden columns.

The second support-point of the inclined rafters is on the purlins. The presence of
the lie over the columns determines the construction of a main carrier frame system
with a individual hinge- rod static scheme. In her behavior play a significant role
“pliers”, that are executed on two levels below the ridge. As a second bearing
structure in the roof form intermediate positioned between columns triangular frames.
They stand on the purlin and also on stone walls. In the roof by the joining of two
sloping ribs with pliers on two levels below the ridge (this time without lie) is formed
in the second configuration static scheme of the roof structure. In 2009, the church
was reconstructed. Restoration of the church is carried out due to cracks in the walls
of the temple. Currently, the state of the church can not be described as satisfactory.
Plaster facades is cracked, as in some places missing targets large pieces(fig.1.1.3a,b).

a) b)
Fig.1.1.3 a,b - Global View and Outside View on the Church “St. Dimitar”

Columns bears the load of the roof structure are severely deformed and distorted,
as each is tilted in different directions (Fig.1.1.4a,b).

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a) b)
Fig.1.1.4 a,b - Inside View of the Church “St. Dimitar

The structure bearing the “iconostasis” of the church is subjected to the aggression
of wood pests, some of the beams and columns with time lost part of its cross section
(Fig. 1.1.5a,b), it is not easy to determine, how much should be reduced the actual
cross-section in the forthcoming static calculations.

a) b)
Fig.1.1.5 a,b - The structure holding the “iconostasis” Inside

Between columns over two galleries along the church developed a vaulted wooden
structural elements(fig.1.1.6a,b). Arch beams are massive wooden elements which are
at the lower end cut to a curved shape, which gives the outline of the arch. Under
these vaulted -beam -elements are attached wooden elements formed the semi -
cylindrical shape, bearing the lime plaster, which gives a curved cylindrical shape of
the arch. Arch beams rely on upper belt of a Virendel structure located between the
wooden columns. Arch beams involved in the configuration of the main support
frame structure on the roof. At the upper end, they are connected with the lower joint
pliers.

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a) b)
Fig.1.1.6 a,b - Vaulted wooden structural elements in the roof of the Church “St. Dimitar”

Wooden columns of the frame within tread on stone foundations(fig.1.1.7a,b).

a) b)
Fig.1.1.7 a,b,c - Wooden columns of the frame within tread on stone foundations

2. ASSESMENT OF THE STRUCTURES

When checking the roof structure we were focussed on the points where
deterioration is expected: supports, roof–valley elements, gutters, etc. Special
attention was also put on signs of biological attack (presence of mould or wooden
dust which indicates an attack of wood fungi and insects). The most problematic parts
of the structure were found on the spots where long term wetting was
present(fig.2.1a,b).
Wetting was caused primarily by leaking at bad details at the gutters and at bad
connections of roof planes. In these parts combined attack of fungi and wood insects
caused substantial deterioration of wood, sometimes even the total loss of cross
section and/or strength. One of the most problematic elements was the main beam
with 3,10m span which was bad enough destroyed due to the attack of wood
destroying fungi. The structural elements of the roof was not rigid enough which

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together with the rearrangement of load to other roof elements caused substantial
deformation(Fig.2.2a,b)

a) b)
Fig. 2.1a,b - Long term wetting is present

a) b)
Fig. 2.2a,b - View on Virendel beam and continuous purlin in the roof construction

Not heavy damage due to insect attack (Hylotrupes bajulus) was spotted. Not only
elements at roof edges and gutter valleys, but also elements in the dry surroundings
were damaged also by the “house capricorn” (Hylotrupes bajulus). However we
estimated that the roof structure in this part of the church is in general worthwhile
preserving. There are two types of floor structures: in the level: +5,570 m, above the
entry floor, mainly hollow floor are installed. In the level of empore mainly massive
timber floors are installed. The stages of deterioration of massive timber elements in
the hollow floor was differed: in some areas only the surface was affected whereas in
some corners practically the whole effective height of joists was affected. The level of
deterioration was evaluated with inspection with chisel and hammer and on some
spots with core drilling(2.3a,b).

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a) b)
Fig. 2.3a,b - View on hollow timber floor, Not so bad deterioration of hollow timber floor
(left); massive timber beam from the floor – damage caused by brown rot (right).

3. STATIC CALCULATIONS AND STRENGTHENING OF THE FLOOR

STRUCTURE OF EMPORIA
Emporia is a rectangular in plan structure with dimensions: 4,67/14,40m(fig. 3.1).
Below it is located narthex of the church. On the floor of the atrium construction is
carried out various activities forming part of the life of the church, and the main
purpose is to ensure the collection of the church choir.

Fig. 3.1 - Structural system of the Emporia

Floor structure of the atrium is a wooden beams. The main structural elements of
the atrium floor beams are supported on both sides on a stone and brick wall. In the
investigation of this part of the structure of the church noticed cracks in the facade of
the church tower. For this reason the project for restoration of the structure comes
concept lashing the wooden floor beams to the stone and brick wall with special
anchors to the wall components. The purpose of these anchoring devices is to

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improve the behavior of the floor structure against horizontal: wind and seismic
actions. Last but not least, this intervention will affect more favorable behavior of the
vertical walls of the church against the effects of the strokes of the bells. As a whole
will improve the dynamic characteristics of the floor structure of the atrium, which
will be reflected on the vibrations of the floor, which according to a number of
normative documents must not exceed certain limits. The project proposes the
implementation of sound and heat insulation of mineral wool thickness 10 cm, which
improves fire safety of the object. Furthermore, in order to improve spatial resistance
atrium provided metal links (PVV) of steel Strips (bus: -4 / 40 mm), which is applied
on the wooden floor of the atrium.
3.1. Load model
All the above components were tested on a vertical load of their weight and useful
load of 300 daN/m2 as well as a concentrated force equal to 150 daN. Checks bearing
capacity are made for strength and deformability according to the "Standards for the
design of wooden structures", BBA, 5 – 6/1990. The quality of the wood, when
testing the structural elements of the atrium is adopted as the second category (SI-II).
In severe defects: deflections of beams, cracking and rotting or destroyed by
biological pests parts there of, at the discretion of the designer these beams can be
paired or, in extreme cases, replaced. Special attention should be paid to the contact
areas between the beams and stone walls.

4. STATIC CALCULATIONS AND STRENGTENING OF THE SPACE

STRUCTURE OF THE BELL TOWER
The construction of the bell tower is a skeleton - beam spatial system from
columns and beams, carried out by wooden elements with solid cross-section. The
columns are visible and with sizes: 20.5 / 21.5 cm. The height of the bell tower to the
roof elevation is equal to 14.40 m(fig.4.1a,b).

a)
b)
Fig. 4.1a,b - Bell tower is a skeleton - beam spatial system from columns and beams

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The total number of columns is 6 pcs. They have two pairs of the front facade of
the west, two above the atrium and a one number in the direction of the north and
south side of the building. Basically this is a hexagon with sides equal to 204, 64 cm
and was developed within a square with approximate dimensions: 2.80/2.80 m. In the
part under the roof of the church this hexagon is supported in space with sloping
swept out of its plane. These are supported swept the floor beams in the two side
galleries located in axis B, C and D. In the plains between the columns are vertical
bracing elements, developed with an "X" shape(fig.4.2a,b).

a) b)
Fig. 4.2a,b - View over the structure of bell tower
4.1. Load model
Load in the belfry is: the weight of the wooden elements, weight of the bells, a
dead load equal of 300 daN/m2 on the elevation, which served bells and snow on
ground level:+ 8.61. Dimensions of all floor beams and of all bell tower columns was
proposed. It was found that their dimensions have sufficient reserves, required by the
rules of computing values of tensions, pressure and bending in the wood, and
therefore do not have their further strengthening.

5. STATIC CALCULATIONS AND STRENGTHENING OF THE FLOOR

STRUCTURE OF THE GALLERIES IN AXIS: A-B AND C-D
Galleries are rectangular in plan structures developed along the stone walls and
with dimensions in plan: 3,65/26,65 m(fig.5.1).
On the floor structure of the galleries are not involved in any activities related to
the life of the church. And the main purpose is to ensure the passage of personnel for
a possible order to determine the state of the roof structure. The floor structure of the
galleries stay open. They are performed by the different sizes joists with distances
from one another, ranges from 450 to 610 mm. The dimensions of the beams range
from 60/120mm in the new part to 200/140mm in the old part. At one end (outer),
beams resting on stone walls and at the other end (internal) beams lie on the main
beam above the columns(fig.5.2a,b).

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Fig.5.1 - Geometrical parameter of the galleries structures

a) b)
Fig.5.2a,b - View over the floor structure in the galleries between axes A-B and C-D

The project proposes laying mineral wool between rafters and nailing of the upper
side of the wooden flooring. The aim is to make this part of the roof structure in stiff
diaphragm, which selected the behavior of the building in horizontal effects. On this
flooring provides a nailing horizontal bracing of metal strips with dimensions: 4/40
mm(fig.5.3a,b).

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a) b)
Fig.5.3a,b - Mineral wool between rafters and nailing of the upper side of the wooden flooring

5.1. Load model

All the above components were dimensioned on a vertical load of their weight and
dead load of 150 daN/m2 as well as a concentrated force equal to 150 daN. Were
studied planking sizes: 4/15, floor and beam sizes: 20/14 cm in axial distance between
them adopted 750 mm. Checks bearing capacity are made for strength and
deformability according to the "Standards for the design of wooden structures",
BBA,. No: 5 – 6/1990.

6. EXAMINATION OF THE STONE WALL OF THE CHURCH OF

SEISMIC EFECT
Check the bearing capacity of the stone walls against seismic effects is made
according to EC8. This problem is solved by a model accepts vertical strip with hinge
joints supported in the most unfavorable cases at both ends. We examine dynamic
system with one degree of freedom. The impact of seismic load is determined by
calculating the horizontal force acting in the middle of the stone wall. This force is
determined, featuring so named seismic coefficient "Sa", which is ordinate from the
diagram of calculation response spectra for a given period of oscillation "Ti" of the
stone wall. Indicator of the behavior of the stone wall in earthquake are stresses, in
mortar lied in masonry wall. Studies show that for ordinary marks mortars, seismic
check is not satisfied. The tensile strength in ordinary marks mortars can not resist the
tensile stress received in them due to seismic forces. Special requests without serious
intervention is practically impossible. However, this requires a serious financial
resources.

7. NUMERICAL ANALYSIS OF THE TIMBER ROOF OF THE CHURCH

The main purpose of this part of the article is to show the potentials of a three
dimensional computer modelling and simulation of a building structure. We would

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like to show how the science of engineering in particular, and advanced computer
modelling including finite element methods(FEM), can be used to increase the
understanding of a structure. We intend to show more than simple strength
calculations, which is the most common range of application of the finite element
method. We will also demonstrate how to apply this method to a historical building
structure. This includes a comprehensive study of the structure in mind, which is done
not only to be able to reveal the geometry, but even more to learn to understand the
structure and its behaviour. This knowledge is necessary to be able to judge the truth
of the results. When the static behaviour of the structure is found we will illustrate
this in a way that is simple to understand even for the less experienced viewer. A
historical wooden framework is very likely to be highly complex and machine of
time. That is why it is very important to be able to study the results of a calculation
when dealing with the framework as an entirely. This includes plots of deformations
and reaction forces on the complete structure, as well as special examination of
smaller sections of the structure. With the computer model needed for the above
analysis it is easy to go further and simulate damage to the structure or exposure to
special load cases. This can be done either to include realistic or probable damage in
the dimensioning when restoring the building, or to verify observed damage. This will
not be demonstrated explicitly in this work, but the possibility will be obvious. As an
additional purpose we will also discuss different methods of analysing building
structures, especially old historical wooden structures. Originating in the different
tools, computer calculations and hand calculations respectively, used in Bulgaria we
will try to investigate how the norms and regulations are used. We are interested in
whether the rules must be completely obeyed or whether they may in some cases take
advantage of the calculation method in question. Within the structural analysis of the
historic timber structure, a model is built(fig. 7.1.a,b,c).

a) b) c)
Fig. 7.1a,b,c - Church St. Dimitar – (a) Main Truss, (b) Longitudinal Truss, (d) 3D View

Of course at all time, the structural model is a compromise between a scheme

close to reality, but too complex to calculate and a scheme, easy to calculate, but far
away from reality. The better the model is in line with reality, the more reliable the
diagnosis will be. Therefore, a step-by-step procedure within the modeling is used.
Initially, with the information available from a visual inspection, a first structural
model is made, often not accounting for detailed information on material degradation,
missing structural elements, actual deformed shape of the structure. The outcome

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results of the structural model are compared with the deficiencies identified on site.
This initial analysis is worth full since it better aligns additional research efforts.
According[5,6] the updated model therefore should ideally account for: - overall
geometry of the timber roof, cross-sections of the structural elements, nodal details,
displacements, missing elements, structural interventions, alterations and weakening;
actual material properties, taking into account the rate of decay (mechanical and
physical-chemical-biological), instead of the material characteristics specified in the
original design or provided by codes; the correct nature of connections and boundary
conditions, including differential settlements of the supports; - the uncertainty
associated with the validity and accuracy of the models. In general, following remarks
can be made: the structural analysis software used (Superstat, Tower) is mainly
developed for the design of new timber structures, according to the limit states design
principles, using partial safety factors; there is no software available that accounts for
the time dependent (creep) behavior of timber. The general frame analysis software
mainly used within practice does not account for the non-isotropic material
characteristics of the timber. Within the analysis different types of nodes are
encountered. The outcome of the analysis results strongly depend on the nodal
stiffness assumed and their actual restrained(fig. 7.2 ).

Fig. 7.2 - Different types of nodes modeled as hinge joints within the structural analysis

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7.1. Load model

Loads are adopted pursuant to Ordinance № 3/2004 years. "Basics of designing
the structure of the buildings and the impacts on them" for the region of Kyustendil as
follows: snow region III with value 132 daN/m2 and wind to area II with value 32
daN/m2. Computing values of these values are achieved by multiplying the normative
values of the two impacts with load factor: = 1.40. Studied are all occurring in
wooden frames species components. Static analysis of the various structural elements
of the roof done according to the methods of structural mechanics and verified with
FEM program "Tower". Static schemes of frames and roof are modeled as plane joint-
rod systems. All fixtures in the wooden structure of the roof are filled with bolt-
screws. Dimensions of the different components of the roof frame of strength,
stability and deformability are carried out according to "Standards for the design of
wooden structures", BBA,. №5 – 6/1990. The quality of the wood, when testing the
structural elements of the roof frame is adopted as a second category (SI-II).

8. REQUIRED REPAIRS AND STRENGTHENING

Static analysis and calculations show that the majority of the used components are
not sufficiently sized and require serious strengthening[1,2,3]. The roof sloped ribs is
necessary to strengthen the side with wooden planks with a thickness of 3 cm and a
height equal to 12 cm. The connections between the elements are implemented with
bolted screws. The purlin under the rafters is necessary type simple beam to
reconstructing in etc. type: swept the purlin. Additional swept implemented by beams
with dimensions 10/10 cm. The connections between the elements are also pursued
with bolted screws. Main beams, which are above the columns and beams on which
step of the two side galleries between axes: A and B; C and D are strengthening with
bilateral attached to the side walls "П" shaped steel elements. Details are offered to
enhance all joints between structural elements of wooden structures on the
roof(fig.8.1a,b,c,d).
Visibly twisted capitals roof is necessary also be reinforced with FRP. (This
decision should be taken, however, after a thorough study of the cost value of these
details). Wooden columns that are in the nave and show significant deviations from
the design position in height, reaching in some of the columns to 6 cm require
reinforced with steel jackets on their height. Currently, the design can not be given a
final decision on the type of the new column, which can be wooden or steel because
the detail of the passage of the columns in the false arches is unknown. New types of
wire rope lies, are put under pillow, between the tops of the columns.(fig. 8.2a,b,c).

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a) b)

c) d)
Fig.8.1.a,b,c,d - Strengthening details in the joints between structural elements

a) b)
Fig. 8.2.a,b - Construction of the new wire rope lies, between the tops of the columns

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Among columns was developed in new project in both directions strip

fundaments(fig.8.3a,b). The function of these strip fundaments is to limit the
independent deformation (displacement and rotation) of the individual stone steps,
thereby improving the behavior of the base of the church during seismic actions. So
described constructive scheme of the roof structure of the church is calculated for
vertical loads from the dead load of the elements, uniformly distributed on the two
slopes of the roof snow and evenly distributed only in one of slopes - snow left and
snow right. Furthermore, calculations are made to wind in the transverse direction.

b)
a)
Fig.8.3a,b - In both directions strip fundaments with the aim to limit the independent
deformation, of the base of the church during seismic actions

REFERENCES
[1] Cruz,H., Yeomans, D.,Tsakanika, E., Macchioni, N., Jorissen, A., Touza, M,
Mannucci, M, Paulo B. Lourenço,B.P., Guidelines for the on-site Assesment of
Historic Timber Structures, International Journal of Architectural Heritage:
Conservation, Analysis, and Restoration, 2013, pp. 25.
[2] Drdácký, M., “Historic Roofs and Timber Frames”, State of the Art Studies”,
European Research on Cultural Heritage, Proceedings of the ARCCHIP
Workshops supported from the EC 5th FP project, ARIADNE 18, Volume 4,
Prague 2006, pp.313-531.
[3] Lorenco, P. B,. Selected case studies for ancient Portuguese timber structures,
Workshop on Earthquake engineering on timber structures, Coibra, Portugal,
2006, pp.1-9.
[4] Partov, D., Stoyanov, Ch., Petkov, M., Project Design for Strengthening of
Timber Roof Construction in Curch St. Dimitar, Kustendil.’
[5] Straka, B., Novotný,M., Krupicová,J., Šmak,M., Šuhajda, K., Vejpustek,Z.,
Konstrukce šikmých střech, Grada Publishing, 2013, Praha 7, pp. 230.
[6] Vinař, J., Kufner,V., „Historické Krovy”, Konstrukce a Statika, Grada
Publishing, Praha, 2004, pp.271.

[107]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Anka STARČEV ĆURČIN
Đorđe LAĐINOVIĆ2
Andrija RAŠETA3
Zoran BRUJIĆ4
Drago ŽARKOVIĆ5

RC PLANE GIRDER STRUT-AND-TIE OPTIMIZATION

ACCORDING TO REINFORCEMENT AMOUNT AND LAYOUT
Abstract: The paper presents discrete topology optimization of reinforced concrete plane girder that
includes the replacement of the full girder with truss system used for determination of girder's stress-
strain state. Program "ST method" is developed for the girder analysis and is used for automatic
determination of the final Strut-and-Tie model shape, stress control in the reinforced concrete elements
and required reinforcement amount. Obtained Strut-and-tie model optimization was carried out according
to the required reinforcement amount and reinforcement layout. The reinforcement layout is achieved by
selecting the chosen tensioned reinforcement directions.

Кey words: optimization, truss model, Strut-and-Tie, "ST method".

OPTIMIZACIJA RAVANSKOG AB NOSAČA STRUT-AND-TIE

MODELIMA PREMA KOLIČINI I RASPOREDU ARMATURE
Rezime: U radu je primenjena diskretna topološka optimizacija armiranobetonskog nosača koja
podrazumeva zamenu punog nosača rešetkastim sistemom na osnovu kojeg se proračunava naponsko-
deformacijsko stanje nosača. Za potrebe analiza napravljen je program "ST method" pomoću koga se
može automatski odrediti konačan oblik Strut-and-Tie modela, izvršiti kontrola napona u elementima
modela i odrediti potrebna količina armature. Optimizacija dobijenih Strut-and-Tie modela urađena je
prema potrebnoj količini armature čiji raspored je dobijen odabirom željenih pravaca zategnute armature.

Ključne reči: optimizacija, rešetkasti nosač, Strut-and-Tie, "ST method".

1)
MSc, University of Novi Sad, Faculty of Technical Sciences, astarcev@uns.ac.rs
2)
PhD, University of Novi Sad, Faculty of Technical Sciences, ladjin@gmail.com
3)
PhD, University of Novi Sad, Faculty of Technical Sciences , araseta@gmail.com
4)
PhD, University of Novi Sad, Faculty of Technical Sciences , zbrujic@gmail.com
5)
MSc, University of Novi Sad, Faculty of Technical Sciences , dragozarkovic@uns.ac.rs

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1. INTRODUCTION
The Strut-and-Tie method analysis can be applied for the part or the entire girder
design when using of conventional analysis method is very complex and impractical,
especially in an abrupt change of static values and/or geometrical properties of the
girder.
Real girder is replaced with the truss system, Strut-and-Tie model, the system of
compressed and tension simple elements. The concrete parts of the girder (surface or
volume) are replaced with compressed elements, and the reinforcement is replaced by
the tensioned truss system elements [1]. The layout of the truss elements is
determined according to the principal stress trajectories of the elasticity theory.
As the behaviour of the reinforced concrete is commonly determined by the
reinforcement layout, therefore, the equivalent truss model, used in the Strut-and-Tie
method for replacing the real reinforced concrete girder, receives additional
conditions and opens the problem of ambiguity in modelling. Thus, the engineering
experience plays an important part in determining the specific solutions.
Optimization of the reinforced concrete members can be achieved according to
their topology and geometry and can be discrete and continuum. Discrete
optimization involves girder modeling with the finite element system, while
continuum optimization takes into account the girder as a continuum [2], [3] and [4].
In discrete optimization the girder is discretised by the truss system where all
points of the girder are connected with simple line elements. Continuum optimization
involves specially arranged material that is difficult to present with the finite
geometric characteristics.
In the paper, the reinforcement amount optimization of the Strut-and-Tie models
according to the reinforcement layout is presented and program "ST method" is
developed for the analysis and can automatically determine the final Strut-and-Tie
model shape, the stress control of the model elements and the required reinforcement
amount.

2. AUTOMATIC DETERMINATION OF THE STRUT-AND-TIE MODELS

The removal of elements from the real system for obtaining replaced truss system
can be performed based on various parameters such as stresses, displacements,
stiffness, strain energy of the system and other. The most common criterion for
certain elements removal of the system is rigidity, which is determined by the
expression, [5] and [6]:
E d N i, j-1
K i, j  i (1)
Li f d
The proposed discrete optimization process of reinforced concrete girder with the
truss system, uses the correction of the simple elements cross section axial stiffness

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(EA) depending on the character and the intensity of forces Ni,j-1 shown in [7], [8] and
[9]. Cross sectional area of individual elements Ai,j, i.e. simple elements of the truss
system, is determined by the expression:
N i, j-1
A i, j  i (2)
fd
The design is performed iteratively. In the first step, after the discretisation, a
network of linear finite elements is formed, with the contour conditions and external
load. All the nodes of the finite element mesh are connected with simple elements. In
the zero iteration, all elements of the model have the same mechanical and
geometrical characteristics of the cross sections. The axial forces in the elements are
determined on the basis of the formulated model.
Since reinforced concrete girder behaviour depends on the manner of
reinforcement layout, coefficient βi in the expression (1) and (2) is the reduction
factor which depends on the required ("desired") reinforcement layout in the girder
(values range from 0 to 1). β value of compressed elements is always 1, tensioned
elements have angle 0°, 45° or 90°, as well as other tensioned elements defined with
values from 0 to 1, [8].
For each successive iteration, a model obtained by the correction of the axial
stiffness of the element cross sections is utilized. The correction is conducted on the
character and the intensity of axial forces in the elements from the previous iteration.
At last, equivalent truss model is formed by the final recognition of the dominantly
loaded elements.

3. NUMERICAL ANALYSIS
Analyzed reinforced concrete deep beam, loaded with two concentrated forces, is
shown in Figure 1, where geometrical and mechanical characteristics of the girder are
also given. Statical system for the analysis is shown in Figure 2.
Finite element model, needed for obtaining of the replaced truss model, according
to proposal manner of discrete optimization implemented in program "ST method", is
shown in Figure 3.

Figure 1. Deep RC beam

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Figure 2. Static system of deep RC beam

Figure 3. FEM model of deep RC beam

Obtained Strut-and-Tie models for different layouts of reinforcement are shown in

Tables 1-4, as well as applied coefficient βi combinations.
The required reinforcement amount for the self weight is the same for all the
analyzed girder models, independently of applied coefficient βi combinations. In
reinforcement amount determination, it is assumed that the main rainforcement
amount of the both side edges of the deep beam for all the analyzed variants is the
same.
Table 1. Strut-and-Tie model of RC deep beam – Variant 1
Variant 1 Parameters for analysis

Ec = 33 GPa, Es = 200 GPa

Compressed element: β = 1
Tensioned element:
(0°) β = 1;
(45°) β = 1;
(90°) β = 1;
(other angles) β = 0.01

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Table 2. Strut-and-Tie model of RC deep beam – Variant 2

Variant 2 Parameters for analysis

Ec = 33 GPa, Es = 200 GPa

Compressed element: β = 1
Tensioned element:
(0°) β = 0.01;
(45°) β = 1;
(90°) β = 1;
(other angles) β = 0.01

Table 3. Strut-and-Tie model of RC deep beam – Variant 3

Variant 3 Parameters for analysis
Ec = 33 GPa, Es = 200 GPa
Compressed element: β = 1
Tensioned element:
(0°) β = 1;
(45°) β = 0.01;
(90°) β = 1;
(other angles) β = 0.01

Table 4. Strut-and-Tie model of RC deep beam – Variant 4

Variant 4 Parameters for analysis

Ec = 33 GPa, Es = 200 GPa

Compressed element: β = 1
Tensioned element:
(0°) β = 1;
(45°) β = 1;
(90°) β = 0.01;
(other angles) β = 0.01

Model with reinforcement tensioned directions of 0°, 45° and 90°, that are favored
equally, represents Variant 1. Variant 2 is represented with the model where
reinforcement tensioned directions of 45° and 90° are favored. Model with desired
reinforcement tensioned directions of 0° and 90° represents Variant 3. Variant 4 is
represented by the model with favored reinforcement tensioned directions of 0° and
45°.
According to the analyzed variants, the results of required reinforcement amount
optimization are shown in Table 5, where percentage difference is obtained according
to the required reinforcement amount for Variant 1. Figure 4 shows dependence of the
required reinforcement amount and the reinforcement layout.

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Table 5. Reinforcement amount optimization

Variant Reinforcement [kg] Percentage difference [%]
1 390 /
2 576 + 47.7
3 430 + 10.3
4 390 0.0

Based on the results above, it can be concluded that the optimum combinations of
βi coefficients are those in Variants 1 and 4, according to required reinforcement
amount.

Figure 4. Reinforcement amount optimization

4. SUMMARY AND CONCLUSIONS

Discrete topological optimization is used for the reinforced concrete deep beam
analysis according to the required reinforcement amount and layout.
Program "ST method" is developed and used for the stress-strain state
determination of the girder and the reinforcement amount.
Applied topological optimization involves removing parts of the girder, ie. simple
elements from the replaced truss system, based on the rigidity criteria, whereby
compressed elements in the model replace the girder concrete parts and tensioned
elements replace reinforcement. Removing certain elements of the truss system is
achieved in iterations, where each iteration removes those elements that are "less"
involved in the load bearing capacity.

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Based on the analysis, it can be concluded that Variants 1 and 4 are the optimum
according to the required reinforcement amount. Also, it can be noted that Variant 3
requires slightly larger amount of the reinforcement, but for its combination of β
coefficients, simpler form of Strut-and-Tie model is obtained compared to other
Variants.
The proposed method for determination of the Strut-and-tie models may provide
several different solutions. This is the result of different β coefficient value choice.
The decision, which model will be chosen, is based on the engineering experience.

ACKNOWLEDGEMENTS
The work has been done within the scientific research project TR 36043
"Development and application of a comprehensive approach to the design of new and
safety assessment of existing structures for seismic risk reduction in Serbia", which is
funded by the Ministry of Science of Serbia.

REFERENCES
[1] Schlaich J., Schäfer K.: Design and detailing of structural concrete using strut-
and-tie models, The Structural Engineer, Volume 69, No. 6, 1991.
[2] Burns S.A.: Recent Advances in Optimal Structural Design, By the Technical
Committee on Optimal Structural Design of the Technical Administrative
Committee on Analysis and Computation of the Technical Activities Division of
The Structural Engineering Institute of the American Society of Civil Engineers,
May 3, 2002.
[3] Bendsoe, Martin Philip, Sigmund, Ole: Topology Optimization, Theory,
Methods, and Applications, Springer EUA, New York, 2003.
[4] Bruggi M. Generating strut-and-tie patterns for reinforced concrete structures
using topology optimization, Computers and Structures 87 (2009), pp 1483-
1495.
[5] Kostić N.: Computer-based development of stress fields, 6th International PhD
Symposium in Civil Engineering, Zurich, August 23-26, 2006.
[6] Kostić N.: Topologie des champs de contraintes pour le dimensionnement des
structures en beton arme, These No 4414 (2009), Ecole Polytechnique federale
de Lausanne, Suisse, 11 Juin 2009.
[7] Starčev-Ćurčin A., Rašeta A., Lađinović Đ.: Determination of Strut-And-Tie
Models for Planar Reinforced Concrete Members, Mase, 14 Internacional
Symposium, Struga, Macedonia, 28.09-01.10.2011., str. 133-138, ISBN 9989-
9785-1-8 (kn. 1).

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[8] Starčev-Ćurčin A., Rašeta A., Brujić Z.: Optimization of RC Plane Elements by
Strut-and-Tie Models, International Symposium about Research and Application
of Modern Achievements in Civil Engineering in the Field of Materials and
Structures, Tara, October 19-21, 2011., Društvo za ispitivanje i istraživanje
materijala i konstrukcija Srbije, Beograd, Kneza Miloša 9/I, Zbornik radova, str.
195-202, ISBN: 978-86-87615-02-1.
[9] Starčev Ćurčin A., Rašeta A., Brujić Z.: Automatic Generation Of Planar Strut-
And-Tie Models, Facta Universitatis, Series: Architecture and Civil Engineering
Vol. 11, No 1, 2013., pp. 1-12, DOI: 10.2298 / FUACE1301001S, UDC
624.04:519.673:624.072.22=111.

[115]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Iliana STOYNOVA
Konstantin KAZAKOV2
Radan IVANOV3

FEM MODELLING OF FLAT SLAB – COLUMN CONCRETE

CONNECTION SUBJECTED TO STATIC LOADING
Abstract: Slab-column connection in the flat slab system is frequently subjected to transverse shear
forces, which can cause a punching shear failure. An overview of the finite element, used for modeling
of concrete members and connections and simulation by the FEM is presented, as well as their
implementation in actual models. The models of concrete analyzed using the ANSYS program. Concrete
model using for nonlinear elastic analysis is according to Eurocode 2, and plasticity of concrete is
described by Willam и Warnke model. The concrete is modeled using SOLID65 finite element.

Кey words: concrete, column-flat slab, structural connection, FEM modelling.

MKE MODELIRANJE BETONSKE VEZE PLOČA-STUB IZLOŽENE

STATIČKOM OPTEREĆENJU
Rezime: Veza ploča-stub u sistemu pune ploče često je izložena transverzalnim smičućim silama, koje
mogu da dovedu do probijanja stuba kroz ploču. Pregled konačnih elemenata koji se koriste za
modeliranje betonskih elemenata i veza, i MKE simulacija su predstavljeni u radu, kao i njihova primena
u realnim modelima. Modeli betona analizirani su upotrebom ANSYS programa. Prikazan je model
betona za nelinearnu elastičnu analizu prema Evrokodu 2, dok je model za plastičnost betona opisan
pomoću Willam i Warnke modela. Beton je izmodeliran upotrebom SOLID65 konačnog elementa.

Ključne reči: beton, stub-puna ploča, strukturalna veza, MKE modeliranje.

1
Assist. Prof., PhD Student, USEA (VSU) „L. Karavelov” Bulgaria,1373 Sofia, Suhodolska str, stoynova@vsu.bg
2
Prof., DSc,Eng, USEA (VSU) „L. Karavelov”Bulgaria,1373 Sofia, Suhodolska str, kazakov@vsu.bg
3
Assoc.Prof., PhD, Eng, USEA (VSU) „L. Karavelov”Bulgaria,1373 Sofia, Suhodolska str, r_ivanov@vsu.bg

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1. INTRODUCTION
Slab-column connection in the flat slab system is frequently subjected to
transverse shear forces, which can cause a punching shear failure. In this paper are
presented characteristics of finite elements, used for modeling of punching shear at
column-flat slab connection. The models of concrete analyzed using the ANSYS
program. The concrete is modeled using SOLID65 element, which is capable of
simulating the cracking and crushing behavior of brittle materials. Concrete model
using for nonlinear elastic analysis is according to Eurocode 2, and plasticity model
of concrete is described by Willam и Warnke model.

2. MATERIAL MODELLING
2.1. Concrete material model according to Eurocode 2
Stress – strain relation for concrete nonlinear structural analysis according to
Eurocode 2 for for short-time uniaxial loading is shown in fig.1 and represented by
the following formula (1)[1]:

( )
(1)

Where:

εc– Compressive strain in the concrete

εc1 – Compressive strain in the concrete at the peak stress fc

| |
(2)

This formula is valid at: ,

Where:
Ecm- Secant modulus of elasticity of concrete
εcu1–Ultimate compressive strain in the concrete
fcm- Mean value of concrete cylinder compressive strength

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Fig.1 Stress-strain relation for concrete nonlinear structural analysis

2.2. Willam& Warnke’s concrete material model for nonlinear plasticity

In ANSYS program concrete nonlinear plasticity is described with Willam and
Warnke’s model. This model belongs to the group of elastic-plastic models with
isotropic softening. By cracking the concrete is considered as a homogeneous
isotropic material. These properties are valid until the occurrence of cracking
concrete; it is assumed that cracks are smeared. [4]
Different constants are requiring for application (3) of the material model of
Willam and Warnke in ANSYS. Tranfer shear stress coeficient - β, described the
conditions on the crack surface. The value of β varies from 0 to 1, where β=0 crack
have smooth (do not carry shear stress), and when value of β=1 – there is rough first
crack (no transfer of shear stress loss).

( )

( ) (3)
√
√

This model is formulated for perfectly elastic-plastic behavior of concrete under

compression and perfectly elastic brittle behavior in tension. Concrete material model
predicts failure as brittle material.

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3. FINITE ELEMENTS, USED FOR CONCRETE MODELLING

For modeling of concrete in ANSYS the finite element SOLID 65 (CONCRET 65)
is used. SOLID 65 (fig.2) is a three-dimensional isoparametric element which allows
cracking in tension and crushing under pressure [3]. Defined by eight nodes, each
node has three translational degrees of freedom. The element can simulate the
interaction between concrete and reinforcement, thus describing the reinforced
concrete behavior. This finite element has the possibility to define the properties of a
solid material - concrete, and up to three different types of reinforcing steel. The most
important feature of the element is that it accommodates both linear and non-linear
behavior of concrete. For the linear phase isotropic material is assumed until crack
initiation. In the non-linear phase of plasticity and creep may be introduced
individually or in combination [2].

rebar

Fig.2. 3-D finite element with 8 nodes and 24 DOF’s SOLID 65

4. NUMERICAL MODELS
The presented numerical models are modelling by ANSYS (fig.3). Two sizes of
flat slabs are considered width= 2,00m., breadth =2.00 m. and depth=0.20 m.
Boundary conditions were adopted: restraints are applied on the contour of the slab
along the axes X, Y and Z. The column sizes is 0.25 / 0.25 m. The concrete properties
are: C20/25, fcm=28 МРа, Ecm=30 GPa , Poison`s ratio is 0,2. Are presented centric
load case of column reaction. The axial force is applied by steps from 2 000 kN/m2
to 12 000 kN/ m2 with step of 2000 kN/ m2, or equivalent reaction from 125 kN to
750 kN by step of 125 kN . The flat slab and the column are modeled with SOLID 65
(CONCRET 65) finite elements as nonlinear elastic material model without
reinforcement – tabl.1. In fig.5 is shown the distributtion of the normal and tangential
stresses on the column – flat slab contact zone (above the edges of the column) in the
section across the y=1.125 m. and load of 12 000 kN/m2 (750 kN). In fig.4 is shown
load-max. displasement relation at first model.

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Table.1. Concrete properties

Concrete С20/25 material model

Linear isotropic
Young’s modulus Еc=3E7 kN/ m2
Poison’s ratio ν=0.2
Nonlinear – Multilinear isotropic
Strain, ε, m/m Stress, σ, kN/m2
0 0
0.000373 11200
0.0005 13176
0.0010 21778
0.0015 26526
0.0020 28000
0.0025 26667
0.0030 22909
0.0035 17043

Fig.3. Non-deformed shape

Displasement, m
1.2
*10-3
1
0.8
0.6
0.4
0.2
0
0 200 400 600 800 Load,kN

Resultant force,kN 125 250 375 500 625 750

Max.displacement,m 0,196.10-3 0,392.10-3 0,593.10-3 0,196.10-3 0,001013 0,001057
Fig.4.Load-max. displasement relation at first model

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a) b)
Fig. 5 a) Diagram of ) Distributtion of the normal and tangential stresses on the column
– flat slab contact zone (above the edges of the column) in the section across the y=1.125 m.
for first model – multilinear elastic concrete behavior

Second model of concrete connection with material properties according to tabl. 3

are presented. Two sizes of flat slabs are considered width= 2,00m., breadth =2.00
m. and depth=0.20 m. Boundary conditions were adopted: restraints are applied on
the contour of the slab along the axes X, Y and Z. The column sizes is 0.25 / 0.25 m.
The concrete properties are: C20/25, fcm=28 МРа, Ecm=30 GPa , Poison`s ratio is 0,2.
Are presented centric load case of column reaction. The loading is applied by step of
500 kN/m2 - from 1 000 kN to 3 000 kN/m2 , or equivalent force from 62,5 kN to
187,5 kN by step of 31,25 kN. The flat slab and the column are modeled by SOLID
65 (CONCRET 65) finite elements as nonlinear plasticity material model without
reinforcement. Different constants for application of the material model of Willam
and Warnke in ANSYS are require (Table 2). In fig.6 is shown load-max.
displasement relation at first model . In fig. 7 is shown the distributtion of the normal
and tangential stresses on the column – flat slab contact zone at load of 3 000 kN/m2
(187,5 kN) (above the edges of the column) in the section across the y=1.125 m. In
fig.8 is shown formed cracks.
Table.2 Concrete material nonlinear inelastic model
1. Open crack transfer coefficient ( βt ) 0,4
2. Closed crack transfer coefficient ( βt ) 0,8
3. Uniaxial cracking stress ( fr` ) 4000 kN/m2
4. Uniaxial crushing stress ( fc` ) 40000 kN/m2

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Displasement, m

*10-3 0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
0 50 100 150 200 Load,kN

Resultant force,kN 62,5 93,75 125 156,25 187,5

Max.displacement,m 0,098.10-3 0,147.10-3 0,196.10-3 0,245.10-3 0,328.10-3
Fig.6.Load-max. displasement relation at second model

a) b)
Fig. 7 a) Diagram of ) Distributtion of the normal and tangential stresses on the column
– flat slab contact zone (above the edges of the column) in the section across the y=1.125 m.
for second model –nonlinear inelastic concrete behavior

Fig.8. Formed cracks at second model

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3. CONCLUSIONS
The latest developments in the finite element method modeling suggest that full
advantage must be taken of them for creating new computational and mechanical
models in order to study the punching process in its full complexity. The further
development and clarification of the presented models with different types of loading,
modeling of cracks initiation and propagation until punching shear occurs,
identification of failure mechanisms, accounting for material and geometric
nonlinearity and other yet unforeseen factors is the subject of future research. With
the development of new and more precise models one of the aims is to achieve and
higher effectiveness of materials and improve the performance of the structure as a
unified organism. Also aims at reducing and optimizing of the cross sections, and this
will reduce and rates carbon [6]. Even the FEM alone provides great opportunities for
simulating and studying the patterns of punching and deformation behavior around
the flat slab – column interface.

ACKNOWLEDGEMENT
The study has been financially supported by the National Science Fund, Project
DFNI E02/10121214, and USEA(VSU) “Lyuben Karavelov”, Projects 02/2013 and
02/2014.

REFERENCES
[1] European standard Eurocode 2 – BDS EN 1992-1-1
[2] ANSYS help – www.ansys.com
[3] Kazakov K., The Finite Element Method for structural modelling, third edition,
ISBN 978-954-322-379-4, GEA 2000 publishing house, Sofia, 2010
[4] Willam, K. J. and Warnke, E. P. (1975). Constitutive models for the triaxial
behavior of concrete. Proceedings of the International Assoc. for Bridge and
Structural Engineering, vol 19, pp. 1- 30.
[5] Kazakov K., Theory of Elasticity; Dynamic and Stability of Structures, ISBN
978-954-322-486-9 USEA (VSU) publishing house, Sofia, (2010);
[6] Ivanova J.,V. Valeva,T. Petrova,W. Becker,A. Yanakieva,Interface delamination
of bi-material structures with different industrial applications in energy
structures, In Proc.: Ist South East Europ. Conf. on Sustainable Develop. of
Energy, Water and Environment Systems, 29 June-3 July, Ohrid, Republic of
Macedonia, Ohrid, (2014)

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Mladen ĆOSIĆ
Boris FOLIĆ2
Radomir FOLIĆ3
Nenad ŠUŠIĆ4

PERFORMANCE-BASED SEISMIC EVALUATION OF SOIL-PILE-

BRIDGE PIER INTERACTION USING INDA
Abstract: The purpose of this paper is to present the methodology for performance-based seismic
evaluation of soil-pile-bridge pier interaction using the incremental nonlinear dynamic analysis (INDA).
The INDA analysis was post processed separately for the pier and for the pile, so that the constructed
PGA=f(DR) curves are in the capacitive domain. For these curves the authors identified the IO, CP i GI
performance levels, while the regression analyses were conducted based on the specific DR and PGA
parameters. Fragility curves were constructed based on the solutions of regression analysis and the
probability theory of log-normal distribution. Based on the results of fragility analysis, reliability curves
were also constructed..

Кey words: INDA, seismic performance, fragility, reliability, artificial accelerograms.

EVALUACIJA SEIZMIČKIH PERFORMANSI INTERAKCIJE

TLO-ŠIP-STUB MOSTA INDA ANALIZOM
Rezime: U radu je prikazana procedura evaluacije seizmičkih performansi interakcije tlo-šip-stub mosta
inkrementalnom nelinearnom dinamičkom analizom (INDA). Postprocesiranje INDA analiza je
sprovedeno posebno za stub, a posebno za šip, tako da su konstruisane krive PGA=f(DR) u
kapacitativnom domenu. Za ovako konstruisane krive određeni su IO, CP i GI performansni nivoi, a na
osnovu određenih DR i PGA parametara sprovedene su regresione analize. Krive povredljivosti su
konstruisane na osnovu rešenja regresione analize i teorije verovatnoće log-normalne raspodele, a za
PGA meru intenziteta. Takođe, konstruisane su i krive pouzdanosti na osnovu rešenja analize
povredljivosti.

Ključne reči: INDA, seizmičke performanse, povredljivost, pouzdanost, veštački akcelerogr.

1)
Dr, independent scientist-researcher, http://matrix-structures.com, mladen.cosic@ymail.com
2)
Mr, University of Belgrade, Faculty of Mechanical Engineering, Innovative center, boris.folic@gmail.com
3)
Prof. emeritus Dr, University of Novi Sad, Faculty of Technical Sciences, folic@uns.ac.rs
4)
Dr, Institute for testing materials - IMS, Belgrade, nenad.susic@institutims.rs

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1. INTRODUCTION
Due to the complexity of phenomena involved in the wave propagation in soil-
structure interaction (SSI), mathematical modelling of this problem is based on a
multidisciplinary approach to the engineering seismology and earthquake
engineering. The soil-structure interaction can be considered by conducting tests on
actual models and/or in the laboratory, using analytical and numerical methods.
Seismic performances are considered in several ways: by applying the deterministic
concept with a single earthquake scenario, based on parametric analysis and the
probabilistic concept. The paper [22] presents a 3D finite element incremental
dynamic analysis study of caisson foundations carrying single-degree of freedom
(SDOF) structures on clayey soil. The emphasis is given to the interplay between the
nonlinearities developed above (superstructure) and, mainly, below ground surface,
either of material (soil plasticity) or of geometric (caisson–soil interface gapping and
slippage) origin. The pile performance analysis by establishing a correlation between
the engineering demand parameters (EDP) and the intensity measure (IM) is
presented in [4]. The general approach of modelling the dynamic interaction of piles
groups in the soil using the hybrid techniques by connecting the finite element
method (FEM) and the boundary element method (BEM) is discussed in [5], while
the various aspects of mathematical and numerical modelling of the complex soil-
piles interaction are presented in [11]. General approaches to analyzing the seismic
performance of piles with the emphasis on various mathematical soil-pile interaction
models are presented in [10]. Modelling the piles and soil using 3D finite elements
and taking into account the influence of plastic nonlinear soil behaviour in seismic
performance assessment is presented in [1].
The number of soil-pile-bridge pier interaction studies based on the incremental
nonlinear dynamic analysis (INDA) is considerably fewer. Therefore, the concept of
this work is focused on modelling the aspects of soil-pile-bridge pier interaction
based on the INDA analysis. In order to understand and complete the methodology of
these analyses, in addition to the INDA, the following was also considered: numerical
modelling of soil-pile-bridge pier interaction and the generation of artificial
accelerograms. Results of numerical simulations were presented and 300 NDA
analyses were statistically processed.

2. SOIL-PILE-BRIDGE PIER INTERACTION

There are several approaches to modelling and analyzing the soil-pile-bridge pier
interaction based on the finite element method, taking into account the development
of geometric and material nonlinearity. Figure 1a shows the actual pile model in the
soil, and with the structure above ground level (bridge pier), while figure 1b shows
the numerical pile model formed from column finite elements, and with the structure
above ground level, also formed using column finite elements. The column finite
elements for modelling the pile and the bridge pier are based on the principle of
nonlinear deformation along the element, where at the cross section level a specific

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fibre discretization is implemented. The cross-section is generally considered through

three sub domains: unconfined concrete, confined concrete and steel. The stress-strain
state at the cross section level is determined by integrating the nonlinear single-axis
stress-strain state of each single fibre. According to Mander [15], the constitutive
model of behaviour for the unconfined and confined domains of concrete is a
nonlinear constant confinement concrete model. The constitutive model of behaviour
of steel reinforcement is a bi-linear elastic-plastic model with kinematic strain
hardening in the nonlinear deformation zone [20].

Figure 1. a) the realistic model of pile in the soil, bridge pier and soil, b) the numerical model
of pile, bridge pier and implicit modelling of soil action

The nonlinear dynamic soil-pile-bridge pier interaction is modelled using the

constitutive model of behaviour for the lateral analysis of piles, where the formation
of gaps under cyclic soil deformation is also taken into account [2]. Effects of cyclic
degradation/hardening of soil stiffness and strength are also taken into account; in
addition, actions in the direction pile axis are also separately modelled, which are
orthogonal to the effects that are introduced by applying this model of interaction.
The hysteretic constitutive model consists of four major parts: backbone curve,
standard reload curve (SRC), general unload curve (GUC) and direct reload curve
(DRC) [3]. Defining the mechanical properties of the constitutive model of the soil-
pile-bridge pier interaction behaviour requires nineteen parameters.

3. ARTIFICIAL ACCELEROGRAMS
The procedure of generating artificial accelerograms is conducted by determining
the spectral density function based on the response spectrum; in this specific case a
pseudo response spectra has been used [9]. This function is used to derive the
sinusoidal signal amplitude the phase angle of which is generated by a random
number function in the range between 0÷2π according to uniform distribution.
Sinusoidal signals are compressed in order to generate accelerograms. In order to

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determine the other properties of the artificial accelerogram, such as duration of

recording, it is necessary to obtain additional information about the expected
earthquake based on the response spectrum. Upon the generation of artificial
accelerograms for representing the record of the free field motion, further analyses are
conducted in order to generate accelerograms for soil layers and bedrock motion. In
this specific case, the soil is considered as a single-layer system, but given the number
of input accelerograms in numerical analyses for simultaneous performance of
numerical integration in time, the single-layer system is considered as a multi-layer
system with the same geo-technical properties. For each individual layer
accelerograms are generated taking that waves are propagating similar to the single-
layer system [14].

4. NUMERICAL SIMULATION RESULTS AND DISCUSSION

Numerical simulations of nonlinear pile behaviour in interaction with the soil were
carried out using the finite element method in the SeismoStruct software [18]. The
pile and pier diameter is dp=1.8m, the pile length is Lp=15m, while the bridge pier
height is Lb=10m. The pier and pile are of circular cross-section with radially
disposed reinforcement consisting of 25 rods of Ø40mm diameter. The cross-section
is discretized to 300 fibres, and a total of 10 integration sectors were considered. The
mass applied to the pier top is m=816t. The constitutive concrete model is defined for
the C 25/30 strength class, according to EC 2 [7]. The constitutive model of steel
reinforcement is also defined according to EC 2 [7]: Es=200GPa and fs,y=435MPa.
The following are the parameters of the constitutive model of soil-pile interaction:
Ko=15000KN/m³, P0=0, Pa=0, α=0.5, αn=1, β=0, βn=1, Flg=31, ep1=1, p1=1, p2=0,
pk=1, ek=1, ps=1, es=1 and ks=0.1. Parameters Fc and Fy are determined in the function
of changes along the soil depth, so that these values were separately identified for the
16 link elements used for modelling the soil-pile interaction based on the p-y curves.
The artificial accelerograms were generated using the Simqke software [21] for the
horizontal elastic response spectra according to EC 8 [8] for type C soil, the peak
ground acceleration PGA0=0.35g, the soil coefficient S=1.2 and damping ratio ξ=5%.
Two groups were considered, each with five artificial accelerograms. The first group
consists of accelerograms of shorter total time of acceleration recording tacc=20s and a
shorter time of stationary domain, where the times of stationary domain initiation and
finalization are ts,i=2s and ts,f=10s, respectively. The second group consists of
accelerograms with longer total time of acceleration recording tacc=40s and a longer
time of stationary domain, where the times of stationary domain initiation and
finalization are ts,i=2s and ts,f=15s, respectively. Accelerograms were sampled at a
time interval of Δt=0.01s, so that sampling frequency is fs=100Hz. For all generated
artificial accelerograms, PGA is obtained to be 0.437g.
After the accelerograms were generated, they were further processed in the Shake
software [19], in order to generate independent accelerograms along the soil depth
a(t)i. The soil domain is discretized to 15 soil layers of 1m thickness, while the
bedrock domain is considered separately, so that for each INDA analysis 16

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simultaneous accelerograms were used in the processing phase. A total of 160

accelerograms were generated in this manner. In INDA analyses, these accelerograms
were simultaneously scaled, so that for a single INDA analysis all 16 accelerograms
were scaled with the same scale factor. First, accelerograms were scaled to the initial
value of PGAs,1=0.1g for h=0 and then incrementally scaled to ΔPGA=0.1g. Given the
differences among the accelerograms and the scale factor, the ultimate scale factors
among the accelerograms for a single INDA analysis are also different. Due to the
large number of generated accelerograms, they are not presented in this paper. For
each INDA analysis, accelerograms were scaled to PGAmax=3g, so the total of 300
NDA analysis were carried out. By processing the INDA analyses the discrete values
Ii(EDPi,IMi) were obtained, which were then interpolated and represent the system
response in the capacitive domain. For the EDP parameter, a global drift (DR), while
for the IM parameter a PGA was selected. Figures 2 and 3 are depicting the DR-PGA
ratio curves for the pier top and the pile head, respectively.

Figure 2. The DR-PGA curve for the pier top: a) the first group of accelerograms, b) the second group of
accelerograms

Figure 3. The DR-PGA curve for the pile head: a) the first group of accelerograms, b) the second group
of accelerograms

Generally, it can be concluded that there is a discrepancy in the soil-pile-bridge

pier system response for two different groups of accelerograms. A difference also
exists when considering the pier and pile response, where slightly higher PGA values
were registered for the pile, as compared to the pier. The drift interval value for the
pier is considered in the range of DR=[020]%, while for the pile this range was
DR=[010]%. The limit states of the soil-pile-bridge pier system were determined by
considering the structural performance level (SPL): immediate occupancy (IO),

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collapse prevention (CP) and the global dynamic instability (GI). For the purpose of
the present study, the appropriate limit state for the IM parameter has been
established based on the EDP parameter according to codes.
The IO performance level is determined by considering the PGA value for the
global drift DRIO of reinforced concrete systems according to SEAOC [17], where DIO
is the displacement for the IO performance level and H is the height. The CP
performance level is determined when the tangent slope to the PGA=f(DR) curve is
equal to 20% of the initial elastic slope DRe of this curve or when DR=10%, where
DCP is the displacement for CP performance level. The GI performance level is
determined for the condition that the PGA=f(DR) curve asymptotically approaches
the horizontal line, where DGI is the displacement for the GI performance level. Based
on the above set criteria for determining the performance level, statistical analyzes
were conducted for each PGA=f(DR) curve. Results of these analyzes are shown in
table 1, sorted separately for the pier and pile. Tags in the table are as follows: PGAm
mean value of the maximum acceleration values, PGAmed median value of the peak
acceleration values, PGAmin minimum value of peak accelerations, σ standard
deviation, v variance.

Table 1. Discrete DRi and PGAi values of specific performance levels for the soil-pile-bridge
pier interaction

In this specific case, a lower drift value has been realized of DRmin=0.9% for the
CP performance level, as compared to the drift value of DRmin=1% for the IOmax
performance level at the pile head. The consequence of this situation is that the pile
can much faster develop the state of pre-collapse in the second group of
accelerograms. The determination of the GI performance level is much more
complicated as compared to the previous IO and CP performance levels. More
precisely, it is obligatory that the PGA=f(DR) curve is horizontal; in many cases,
however, this condition is optional, unless the sign of inclination of the PGA=f(DR)
curve changes from positive to negative value. This condition is achieved only in one
case, in DRmin=18.6% and PGA=0.39g for the pier, while in other cases the GI
performance level is determined based on the maximum drift value.

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Unlike the previously presented deterministic methods of evaluation of

performance levels and the conditions of the soil-pile-bridge pier interaction system,
based on the theory of probability it is possible to consider the system's fragility. The
probabilistic concept in the analysis of the soil-pile-bridge pier interaction system is
based on a qualitative consideration of the damage level according to HAZUS [12]:
slight, moderate, extensive and complete. These damage levels are defined as a
function of the system ductility μ, so that the level of slight damage is equivalent to
1<μ<2, the level of moderate damage is equivalent to 2<μ<4, the level of extensive
damage is equivalent to 4<μ<7, while the level of complete damage is equivalent to
μ>7 [6]. The intensity parameter IM is commonly considered by identifying the
appropriate response spectra with the variation of standard deviation ±σ, which is a
function of uncertainty of the seismic demand that is imposed to the structure.
However, in this study, a variation of seismic demand is applied which is a function
of scaling the IM parameter, i.e. the PGA, according the INDA analysis. In this sense,
it is possible to consider a much wider range of seismic demand variations
PGA=[01]g without any further extrapolation. The relation between μ and PGA was
determined based on regression analysis for the linear function of lnμ=k·lnPGA+n.
The fragility curve was constructed in relation to the PGA intensity measure by
using the log-normal distribution, the probability density function. The cumulative
distribution function on the occurrence of damage is determined by [13], where erfc is
the complementary error function and Φ is the cumulative distribution function. The
discrete probability functions for the pier and pile are shown in figures 4a and 4b,
respectively. A lower level of damage is typical up to PGA=0.2g for the pier model,
while for the pile, this value is up to PGA=0.3g.

Figure 4. Discrete probability functions: a) pier, b) pile

The cumulative probability distribution function of damage for the seismic soil-
pile-bridge pier interaction is shown in figures 5a and 5b for the pier and pile,
respectively. The upper limit of the complete damage level is considered for μsup=20,
whereby the changes of this limit significantly affect the cumulative probability
distribution function of complete damage. By comparing the obtained solutions for
the pier and pile, it can be concluded that the pier is more sensitive to the changing
levels of intensity measures PGA. The consequence of this is that the same PGA level
results in larger damage to the pier, where the development higher intensity damage is
also more likely.

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Figure 5. Fragility curves for seismic soil-pile-bridge pier interaction: a) pier, b) pile

Typical values for seismic intensity measures PGA=[0.10.5]g and the

corresponding probabilities of fragility Pi for seismic soil-pile-bridge pier interaction
are shown in table 2. Values of fragility probability beneath the diagonal in table 2 are
typically equivalent to 1 or very close to this value, while those above the diagonal
are typically equivalent to 0 or very close to this value. The values on the diagonal
itself and near to it in table 2 are declining. If, for example, the value of PGA=0.1g,
then it can be concluded that at all fragility levels of the pier are higher than that of
the pile. Thus, for the level of slight damage, the probability of pier and pile fragility
are equal to P=0.88 and P=0.04, respectively, while for the level of extensive damage
this value is P=0 for both the pier and the pile. On the other hand, for PGA=0.3g, the
probability of pier and pile fragility for the level of slight damage are P=1, while for
the level of extensive damage is P=0.99 and P=0.03, respectively.

Table 2. Probability of fragility Pi for the typical seismic intensity measure PGAi of the soil-
pile-bridge pier interaction

Evaluation of the system performance is also performed by analyzing the system

reliability state. When applying this analysis a more complete answer is obtained
regarding the system state, and it is based on the previously considered fragility
analysis. System reliability R is defined by [16]. A negative R coefficient value
indicates a possible failure and system unreliability, while a positive R coefficient
value indicates that the failure probability is approximately equal to 0, i.e. that the
system is reliable to a significant degree. When the R coefficient value is ≈6, then the
system reliability is ≈100%, while in the case when R≈0, the system failure
probability is P=50%. Reliability curves for the seismic soil-pile-bridge pier
interaction are shown in figures 6a and 6b for the pier and pile, respectively.

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Figure 6. Reliability curves for the seismic soil-pile-bridge pier interaction: a) pier, b) pile

Comparing the solutions obtained for the pier and pile, it can be concluded that the
pier is more sensitive to the changing levels of intensity measure PGA, so that higher
levels of uncertainty can be expected at lower PGA values, as compared to the pile.
For P>50%, pier reliability at slight level of damage is PGA≤0.08g, at moderate level
of damage is PGA≤0.14g, at extensive level of damage is PGA≤0.22g and at complete
level of damage is PGA≤0.45g. For P>50%, pier reliability at slight level of damage
is PGA≤0.13g, at moderate level of damage is PGA≤0.24g, at extensive level of
damage is PGA≤0.39g and at complete level of damage is PGA≤0.8g.

5. SUMMARY AND CONCLUSIONS

In this study, a numerical model has been developed for the soil-pile-bridge pier
interaction in order to evaluate the system's seismic performance. Effects representing
the influence of soil were introduced by applying the principle of implicit modelling
the nonlinear dynamic soil-pile-bridge pier interaction. The input signal to the system
is treated through the generated artificial accelerograms, which were further
processed by layers of soil and bedrock. The system response is analyzed in the
capacitive domain using the incremental nonlinear dynamic analysis (INDA). The
INDA analysis was processed in a successive manner by scaling the nonlinear
dynamic analysis (NDA) according the defined scaling criteria.
The NDA and INDA analyses were post processed according to the global drift
DR and the corresponding PGA values separately for the pier and separately for the
pile, so that curves PGA=f(DR) were constructed in the capacitive domain. The IO,
CP and GI performance levels were determined for these curves, and based on
specific DR and PGA parameters regression analyses were carried for the linear
function lnμ=k·lnPGA+n. The fragility curves were constructed based on the
solutions of regression analysis and the probability theory of log-normal distribution
for the PGA intensity measures. The intensity measure IM is typically considered by
identifying the corresponding response spectra with the variation of standard
deviation ±σ, which is a function of uncertainty of seismic demand that is imposed to
the structure. However, in this study the authors applied a variation of seismic
demand in a function of scaling the IM parameter, or PGA according to the INDA
analysis. In this sense, it is possible to consider a much wider range of variation in
seismic demand PGA=[01]g without any further extrapolation. By comparing the
obtained solutions of the fragility curve for the pier and pile, it can be concluded that

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the pier is more sensitive to the changing levels of intensity measure PGA, than the
pile. Thus, the same PGA level results in larger damage to the pier, where the
development of higher intensity damage is also more likely. Based on the solutions
obtained in fragility analysis, reliability curves were also constructed. By comparing
the obtained solutions for the pier and pile, it can be concluded that the pier is more
sensitive to the changing levels of intensity measure PGA, so that it can develop
higher levels of uncertainty at lower PGA values, as compared to the pile. The
methodological procedure for seismic performance analysis presented in this study
provides an integrated quantitative and qualitative consideration and evaluation of the
complex soil-foundation-structure interaction (SFSI).

REFERENCES
[1] Alfach M. (2012) Influence of Soil Plasticity on the Seismic Performance of Pile
Foundations - a 3D Numerical Analysis, Jordan Journal of Civil Engineering,
6(4), pp. 394-409.
[2] Allotey N., El Naggar M. (2008) A Numerical Study Into Lateral Cyclic
Nonlinear Soil-Pile Response, Canadian Geotechnical Journal, 45(9), pp. 1268-
1281.
[3] Allotey N., El Naggar M. (2008) Generalized Dynamic Winkler Model for
Nonlinear Soil-Structure Interaction Analysis, Canadian Geotechnical Journal,
45(4), pp. 560-573.
[4] Bradley B., Cubrinovski M., Dhakal R. (2008) Performance-Based Seismic
Response of Pile Foundations, Geotechnical Earthquake Engineering and Soil
Dynamics IV, ASCE Geotechnical Special Publication 181, Sacramento, USA.
[5] Chen F., Takemiya H., Shimabuku J. (2004) Seismic Performance of a Wib-
Enhanced Pile Foundation, The 13th World Conference on Earthquake
Engineering, Paper No. 1273, Vancouver, Canada.
[6] Choi E., DesRoches R., Nielson B. (2004) Seismic Fragility of Typical Bridges
in Moderate Seismic Zones, Engineering Structures, 26(2), pp. 187-199.
[7] Eurocode 2 (2003) Design of Concrete Structures - Part 1-1: General Rules and
Rules for Buildings, European Committee for Standardization.
[8] Eurocode 8 (2004) Design of Structures for Earthquake Resistance - Part 1:
General Rules, Seismic Actions and Rules for Buildings, European Committee
for Standardization.
[9] Fahjan Y. (2010) Selection, Scaling and Simulation of Input Ground Motion for
Time History Analysis of Structures, Seminar on Earthquake Engineering and
Historic Masonry, University of Minho, Braga, Portugal.
[10] Finn W. (2004) Characterizing Pile Foundations for Evaluation of Performance
Based Seismic Design of Critical Lifeline Structures, The 13th World
Conference on Earthquake Engineering, Paper No. 5002, Vancouver, Canada.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[11] Folic B., Folic R. (2008) Design Methods Analysis of Seismic Interactions Soil-
Foundation-Bridge Structures for Different Foundations, NATO Advanced
Research Workshop 983188: Coupled Site and Soil-Structure Interaction Effects
with Application to Seismic Risk Mitigation, Borovets, Bulgaria.
[12] HAZUS (1997) Earthquake Loss Estimation Methodology, National Institute of
Building for the Federal Emergency Management Agency.
[13] Johnson N., Samuel K., Balakrishnan N. (1994) Continuous Univariate
Distributions, Vol. 1, Wiley-Interscience, New York, USA.
[14] Kramer S. (1996) Geotechnical Earthquake Engineering, Prentice Hall.
[15] Mander J., Priestley M., Park R. (1988) Theoretical Stress-Strain Model for
Confined Concrete, Journal of Structural Engineering, 114(8), pp. 1804-1825.
[16] Nateghi-a F., Shahsavar V. (2004) Development of Fragility and Reliability
Curves for Seismic Evaluations of a Major Prestressed Concrete Bridge, The
13th World Conference on Earthquake Engineering, Paper No. 1351, Vancouver,
Canada.
[17] SEAOC (1999) Blue Book: Recommended Lateral Force Requirements and
Commentary, Report prepared by Structural Engineers Association of California.
[18] SeismoStruct, URL: http://www.seismosoft.com
[19] Shake: URL: http://www.proshake.com
[20] Simo J., Hughes T. (1998) Computational Inelasticity, Springer-Verlag.
[21] Simqke: URL: http://dicata.ing.unibs.it/gelfi/software/simqke/simqke_gr.htm
[22] Zafeirakos A., Gerolymos N., Drosos V. (2013) Incremental Dynamic Analysis
of Caisson-Pier Interaction, Soil Dynamics and Earthquake Engineering, 48, pp.
71-88.

[134]
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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Meri CVETKOVSKA
Marijana LAZAREVSKA2
Ana TROMBEVA-GAVRILOSKA3

INFLUENCE OF THE SHAPE OF THE CROSS SECTION AND THE

AXIAL FORCE ON THE FIRE RESISTANCE OF RC COLUMNS
Abstract: The influence of the shape and the dimensions of the cross section on the fire resistance of
centrically loaded reinforced concrete columns is presented in this paper. A set of columns with same
cross-sectional area, same percentage of reinforcement and different column’s side ratio: 30x30cm,
25x36cm, 20x45cm and 60x15cm (RC wall) are analyzed. Columns are exposed to ISO834 standard fire
from all sides and all over the height. In order to define the influence of the load level on the fire
resistance of the columns, the intensity of the axial compressive force was varied. For the analyzed series
of columns, the fire resistance curves as function of the shape of the cross-section and the intensity of the
axial compressive force were designed.

Кey words: RC columns, fire resistance, parametric analysis, fire resistance curves.
.

UTICAJ OBLIKA PRESEKA I INTENZITETA AKSIJALNE SILE NA

POŽARNU OTPORNOST AB STUBOVA
Rezime: U radu je analiziran uticaj oblika i dimenzija poprečnog preseka centrično opterećenih
armiranobetonskih stubova na njihovu požarnu otpornost. Analizirana je serija stubova sa istom
površinom poprečnog preseka i istim procentom armiranja, a različitim odnosom strana: 30x30cm,
25x36cm, 20x45cm i 60x15cm (platno). Stubovi su izloženi dejstvu standardnog požara ISO834 sa svih
strana i po celoj visini. Kako bi se definisao uticaj nivoa opterećenja na požarnu otpornost stubova,
variran je intenzitet aksijalne sile pritiska. Za analiziranu seriju stubova konstruirane su krive požarne
otpornosti stubova u funkciji oblika poprečnog preseka i intenziteta aksijalne sile pritiska.

Ključne reči: AB stubovi, požarna otpornost, parametarska analiza, krive požarne otpornosti.

1
Prof., Faculty of Civil Engineering, Partizanski odredi 24, Macedonia, cvetkovska@gf.ukim.edu.mk
2
Assist. Prof., Faculty of Civil Engineering, Partizanski odredi 24, Macedonia, marijana@gf.ukim.edu.mk
3
Assoc. Prof., Faculty of Architecture, Partizanski odredi 24, Macedonia, agavriloska@arh.ukim.edu.mk

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1. INTRODUCTION
The columns as structural elements have an important role in preventing loss of
global stability of structures under fire. If these elements do not suffer failure,
damages shall be of a local character, which shall enable evacuation and efficient
extinguishing of the fire. The fire resistance of centrically loaded RC columns
depends on: shape and dimensions of the cross section; concrete cover thickness; type
of aggregate; compression strength of concrete; steel ratio, intensity of the axial force,
as well as the fire scenario [1,3,4].
The set of columns with height h=3m, with same cross-sectional area of 900cm2,
same percentage of reinforcement of 1% and different column’s side ratios: 30x30cm,
25x36cm, 20x45cm and 60x15cm (RC wall) were analyzed in this study. The
columns were exposed to ISO834 standard fire from all sides and all over the height.
All columns were fixed at the bottom side and pin-ended on the other side and such
support conditions were chosen to enable free expansion in longitudinal direction. As
a result of the column’s height and the dimensions of the cross sections, small
slenderness ratios were achieved. In such case the support conditions had a negligible
impact on the fire resistance of the columns and were not varied in this study.
Siliceous aggregate concrete was used and the compressive strength at ambient
temperature was fc(20C)=30MPa. The yield strength of the reinforcing bars at
ambient temperature was taken to be fy(20C)=400MPa.
In order to define the influence of the load level on the fire resistance of the
columns, the intensity of the axial compressive force was varied. The load coefficient
α was defined as ratio between the applied axial force and the ultimate axial force of
the column at ambient temperature. The load coefficient α was varied between α=0.1
and α=0.4.
Because of the symmetry of the cross sections and the symmetry of the fire load,
only one half of the cross sections were analyzed. The cross sections were discretized
by isoparametric four node rectangular elements. The same finite element meshes
were used for the thermal and the stress-strain analysis.

2. FIRE RESISTANCE ANALYSIS OF RC COLUMNS

2.1. Thermal analysis of RC columns exposed to fire
The time dependent temperature field in the cross section of the column exposed
to fire depends on: intensity of the fire and the time of fire exposure; position of the
element with respect to the flames; element geometry; conduction coefficients and the
specific heats of the materials; the processes of heat transfer by convection and
radiation.
The program FIRE-T (Fire Response-Thermal analysis) [1] was used for defining
the time dependent temperature distribution in the cross sections of the analyzed

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columns. While the nonlinear and transient temperature field was determined, the
following assumptions were made:
 A fire was modeled by a single valued gas temperature history-ISO834;
 Temperature dependent material properties were known (recommended in
Eurocode 2, part 1-2 [2]);
 Two dimensional heat transfer was assumed;
 No contact resistance to heat transmission at the interface between the
reinforcing steel and concrete occurred;
 The easier heat penetration, while cracks appeared, or some parts of the cross
section crushed, was neglected.
Numerically achieved results for the temperature distribution in the cross sections
of two types of columns, from the set of analyzed columns, for two characteristic
moments, are presented on Figure 1 and Figure 2.
By comparison of the isotherms in the cross sections it could be found out that in
case when the ratio between the two sides of the cross section is higher (for example
15x60cm), the temperature penetrates dipper in a shorter time period and the average
temperature of the cross section is higher than in case when the ratio is less or equal
to one (case of column 30x30cm). This results with higher reduction of material
properties and reduction of the bearing capacity of the column. Consequently the
column has lower fire resistance.
15 15

10 10
1000 1000
900 900
5 800 5 800
a x is o f s y m m e tr y

a x is o f s y m m e tr y

700 700
600 600
0 0
500 500

400 400

300 -5 300
-5
200 200

100 100

-1 0 20 -1 0 20

-1 5 -1 5
0 5 10 15 0 5 10 15

t=1 h t=2 h
Figure 1- Temperature distribution in the cross section of the column with
dimensions 30x30 cm, for two characteristic moments

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1000
900
5
800
a x is o f s y m m e tr y
700
600
0
500
400

-5 300
200

0 5 10 15 20 25 30 100
20 t=1 h
1000
900
5
800
a x is o f s y m m e tr y

700
600
0
500
400

-5 300
200

0 5 10 15 20 25 30 100
20 t=2h
Figure 2- Temperature distribution in the cross section of the column with
dimensions 15x60 cm (RC wall), for two characteristic moments
2.2. Stress-strain analysis of RC columns exposed to fire
The analysis of the RC columns exposed to fire have to take under consideration
the following aspects: changes in the mechanical properties of the materials due to
temperature changes, the degradation of the cross-section due to the occurrence of
cracks and crushing of concrete, increased effects of creep and shrinkage of materials,
as well as restrained thermal dilatations in the longitudinal direction and within the
cross-section.
The response of a reinforced concrete elements and plane frame structures exposed
to fire is predicted by modulus FIRE-S (Fire Response-Structural analysis) [1].
The modulus FIRE-S accounts for:
 dimensional changes caused by temperature differences,
 changes in mechanical properties of materials with changes in temperature,
 degradation of sections by cracking and/or crushing
 acceleration of shrinkage and creep with an increase of temperature.
The solution method used in FIRE-S is nonlinear direct stiffness procedure
coupled with time step integration. Within a given time step an iterative approach is
used to find a deformed shape resulting in equilibrium between internal stresses and

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external loadings. The internal stresses are function of: current deformed shape;
current temperature distribution; prior response and thermal history.
In each time step on the basis of defined temperature field, the deformed shape of
the column is defined as function of the intensity of the external loads and internal
forces. The analysis stops at the moment when the element collapses as a result of the
crushing of concrete parts of the cross section.
As part of the analysis, besides the shape and the dimensions of the cross sections
of the fire exposed columns, the intensity of the axial force was varied too. The load
coefficient α was involved as ratio between the applied axial force and the ultimate
axial force of the column at ambient temperature. The load coefficient α was varied
between α=0.1 and α=0.4. This enabled comparison of the fire resistance of the
analyzed set of columns with different shapes and sizes, for different load levels.
Numerically achieved results for the stresses in the concrete part of the cross
sections of the two types of analyzed columns, for load coefficient =0.35 and for
two characteristic moments, are presented on Figure 3 and Figure 4.
At first moments of fire expose, because of the high temperature differences
between the surface layers and inner layers and because free thermal expansion is not
allowed, the concrete core cracks. This effect happens when load coefficient is less
than 0.3 and is not so much expressed when the ratio between the two sids of the
cross section is higher. For example, in case of column 15x60cm (Figure 4) this effect
doesn’t appear for load coefficient higher than 0.2. After a time high temperatures
penetrates dipper into the cross section, mechanical properties of steel and concrete
are reduced and the effect of the axial force becomes dominant, so cracks are closed.
15 15 15

10 10 10

2 2 0

5 5 5
0 0 -4

-2 -2 -8
0 0 0
-4 -4 -1 2

-6 -6 -1 6
-5 -5 -5

-8 -8 -2 0

-1 0 -1 0 -1 0 -1 0 -1 0 -2 4

-1 5 -1 5 -1 5
0 5 10 15 0 5 10 15 0 5 10 15

t=0.5 h t=1.0 h t=3.1 h (before failure)

-cracked concrete - crushed concrete
Figure 3- Time redistribution of stresses in the cross section of centrically loaded RC column
with dimensions 30x30 cm, exposed to fire from all sides, (load ratio  = 0.25)

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-1
5
-2

-3
0
-4

-5
-5
-6

-7
0 5 10 15 20 25 30
-8 t=0.5h

-1
5
-2

-3

0 -4

-5

-6
-5
-7

-8
0 5 10 15 20 25 30
-9 t=1,0 h

-2
5
-4

-6
0
-8

-1 0
-5
-1 2

-1 4
0 5 10 15 20 25 30
-1 6t=1.9 h
(before failure)
Figure 4 - Time redistribution of stresses in the cross section of centrically loaded RC column
with dimensions 15x60 cm (RC wall), exposed to fire from all sides, (load ratio  = 0.25)

For the analyzed set of columns, the fire resistance curves as function of the shape
of the cross-section and the intensity of the axial compressive force were constructed
(Figure 5). These curves indicate that the highest fire resistance achieves the column
with lowest ratio between the two sides of the cross section. The reason for that is the
lowest average temperature of the column’s cross section.

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0.5

0.4 column
столб 30x30
30x30
column
столб 45x20
45x20
load coefficient 

0.3 column
столб 60x15
60x15
column
столб 36x25
36x25
0.2

0.1

0
1

4
1.5

2.5

3.5
Fire resistance (h)
Figure 5 – Fire resistance curves for centrically loaded RC columns exposed to fire from all
sides, as function of the shape of the cross section and the load coefficient α

The total axial dilatation of the columns as result of the total thermal elongation
and the negative axial dilatation caused by the compressive axial force, for all four
RC columns exposed to fire from all four sides and for the load coefficient α=0.35,
are presented on Figure 6.

column 30x30
column 25x36
column 20x45
column 15x60

Figure 6 – Axial dilatation of the centrically loaded RC columns exposed to fire from all sides,
for load coefficient α=0.35, as function of the shape of the cross section

If we analyze the total axial dilatation of the columns as function of the intensity
of the axial force and the time of fire exposure, it can be noticed that for all four
shapes of cross sections at the beginning of the heating process the positive dilatations

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caused by temperature are dominant. The negative dilatations caused by the axial
force decrease with tendency to become positive, which is case for load coefficients
less than 0.3.
After a time the average temperatures of the column’s cross sections become
higher, the mechanical characteristics of the steel and concrete are reduced, the
negative dilatations are dominant again and significantly larger than the positive
dilatations caused by temperature. As a result of that, the columns fail in
compression. The most sensitive is the cross section with dimensions 15x60 cm (due
to a higher average temperature), and the best behavior shows the cross section with
dimensions 30x30cm.

3. CONCLUSIONS
Based on the results of the analysis conducted in this study it was found out that in
case of fire exposure from all four sides and action of axial compressive force there is
a significant difference in the behavior of the columns with same cross sectional
areas, but different shapes of the cross sections.
Due to the compactness of the cross section the column with dimensions 30x30 cm
has the lowest average temperature, consequently the highest fire resistance. It is not a
case with the column 15x60cm (RC wall) because in this case the temperature easier
penetrates deeper into the cross section, the column reaches the highest average
temperature and has the smallest fire resistance.

REFERENCES
[1] Cvetkovska, M., 2002. Nonlinear Stress Strain Behavior of RC Elements and
Plane Frame Structures Exposed to Fire, Doctoral dissertation, "Ss Cyril and
Methodius" University, Macedonia
[2] EN 1992-1-2. 2004. Design of concrete structures - Part 1-2: General rules.
Structural fire design
[3] Lazarevska, M., Knežević, M., Cvetkovska, M., Ivanišević, N., Samardzioska,
T., Trombeva-Gavriloska, T., 2012. Fire resistance prognostic model for
reinforced concrete columns, Gradjevinar 64, pp 565-571
[4] Lin, T.D. Zwiers, R.I. Burg, R.G. Lie, T.T. & McGrath R.J., 1992. Fire
resistance of reinforced concrete columns, PCA Research and Development
Bulletin RD101B, Skokie, Illinois, Portland Cement Association

[142]
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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.041
1
Ľuboš ŠNIRC
Monika NAGYOVÁ2
Ján RAVINGER3

FORMS FOR PRODUCTION OF PRESTRESSED PREFABRICATES

Abstract: In the production of prestressed concrete prefabricates T type or double T type cross section
we can have the situation that the form could be more than 100 m long and prestressing force is self-
fixed. Putting the polystyrene in the form and cutting cables we can produce 10 or more beams in one
step. From a viewpoint of theoretical background horizontal deformations represents a problem of
stability and friction.
Another problem we have in the case of bridges produced from prestressed concrete prefabricates. The
costs for transport of prefabricates is very high. A special steel assembled frame for a production of
prestressed prefabricates could be arranged close to bridge site.

Кey words: prestressed concrete, steel frame, bridges, initial imperfection, stability, buckling

OPLATE ZA PROIZVODNJU PREDNAPREGNUTIH PREFABRIKATA

Rezime: Prilikom proizvodnje prednapregnutih betonskih prefabrikata poprečnog „T“ ili „TT“ preseka
može se dogoditi da dužina oplate bude veća od 100 m i sila prednaprezanja fiksna. Postavljanjem
polistirena unutar oplate i prekidanjem kablova, možemo proizvesti 10 ili više greda u jednom koraku.
Sa aspekta teorijske osnove - horizontalne deformacije predstavljaju problem stabilnosti i trenja.
Dodatni problem javlja se u slučaju izvođenja mostova od prednapregnutih betonskih prefabrikata. Cena
transporta prefabrikata je veoma visoka. Moguće je montirati specijalni čelični ram za proizvodnju ovih
elemenata u blizini gradilišta.

Ključne reči: prednapregnuti beton, čelični ram, mostovi, inicijalna imperfekcija, stabilnost, izvijanje

1
Ing., Faculty of Civil Engineering STU, SK-81005 Bratislava, Radlinskeho 11, SVK, e-mail:lubos.snirc@stuba.sk
2
Ing., PhD., e-mail: monika.nagyova@stuba.sk
3
Dr.h.c. prof. Ing.,DrSc., e-mail: jan.ravinger@stuba.sk

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1. FORM FOR THE PRODUCTION OF PRESTRESSED CONCRETE

BEAMS
In the production of prestressed concrete beams we have a situation that the
prestressing force is self-fixed in the form – Figure 1. The form could be more than
100 m long. Inserting polystyrene plates in the form it is possible to produce ten or
more prefabricates in one step.

Steel form Polystyrene Prestressing cable 4000 kN

Figure 1 – The scheme of the steel form for the fabrication of the prestressed concrete beams

50

200
300
Prestressing cable

950
A=0.0646 m2
Ix=8.527*10-3 m4
Iy=26.66*10-3 m4 100

Friction

Figure 2 – Cross section of the form for the fabrication of prestressed concrete beams

Cross section of the form is in Figure 2. Weight of the form is 900 kg/m. Using
linear analysis is enough to follow the vertical deformation of form – Fig.3. Two
millimetres was the limit for maximum vertical deformation of the form. To satisfy
this condition additional vertical load (concrete blocks) had to be used.
In the case of horizontal deformation we have to solve the stability of beam with
the friction forces along a beam.
The span of the form is 120 m and in that case the Euler's elastic critical load is
much smaller than prestressing force. Friction forces could be taken as transverse
load. Transverse load never increases the elastic critical load. Simplification using the
model of buckling of the column with elastic supports has been used. Nine elastic
supports could be taken as elastic foundation – Fig. 4. Results are presented with real
dimensions and forces.
For the evaluation of friction effect following procedure has been used. In Figure
5 is processed non-linear solution when considering the relatively small support
stiffness (k = 20 kN/m). When the load level equal prestressing force (4000 kN) the
deflection of a beam is w  0.19 m . For the determination of deflection springs we
subtract the initial deformation w  0.19  0.05  0.14 m

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Load in a spring is Fp  k * w  20* 0.14  2.8 kN . This force accounts for one
spring.
Distance between springs is 12 m, and therefore the friction force, per spring
is Ft  0.8 * 900* 10* 12  86400N  86.4 kN . (Deadweight of the form is 900 kg/m,
friction coefficient is 0.8.)
We see that the friction force is significantly lower than the load in spring. This
argument entitles us to state that the form will be stable.
In this case the amplitude of the initial deformations was 0.05 m. We see that
result is heavily dependent on this value. Realizing other calculations for different
values of initial deformation of the form will be the subject to further researches.
The nonlinear solution taking into account continouous elastic supports are presented
in Figures 5 and 6. These results give us the displacements of a support and
multiplying this value with the stiffness of support we have transverse force. If this
force is smaller than friction force, we can assume the structure as a stable one.
F0 F0
q F=4000 kN
F
e=250 mm
l=64.0 m

q=5.487kN/m, F0=0

q=10.5kN/m, F0=0 [ ]

q=10.5kN/m, F0=10.0 kN ( )

11.1
„mm“

[87.7]
(105.0)
-20.0

[24.7]
(35.2)

-24.0
[-8.43]
(-3.63)

[-12.5]
(-10.9)

Figure 3 – The approximate solution for unilateral support

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Fcr [kN]
*10
3

30 E,I,A F

k k
l

20 Fcr

Buckling mode k>kcr

l=120.0 m
10
Fcr E=210*106
kPa
Buckling mode k<kcr A=0.0646 m2
buckling -3
kcr=121 kN/mI=26.66*10
4
m k [kN/m]
0 50 100 150 200

Figure 4 – Influence of the stiffness at continuous supports for elastic critical load

F0 [kN]*103
Fcr=6270 kN
6

5
Level of prestressing
4
forces 4000 kN
w0=0.01
w F
0
3 k1
0.05 k1 k l
0.10 1
l=120.0 m
2 E=210*106 kPa
0.25
A=0.0646 m2
1 I=26.66*10-3 m4
0.50 k=20 kN/m
w [m]
0 0.5 1.0
Figure 5 – Nonlinear solution for the buckling of a beam on the elastic foundation

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F0 [kN]*103
Fcr=13466.0 kN
14

12

10

8 w F
0
w0=0.01 k1
6 k1 k l
0.10 1

0.25
4 k=100.0 kN/m
0.50

w [m]
0. 1.0 2.0
Figure 6 – Dependence of the force and deflection in a continuous beam supported by
higher stiffness in supports

2. STEEL FRAME FOR PRODUCTION OF BRIDGE PRESTRESSED

PREFABRICATES
Using a special heavy steel frame, the prestressed concrete continuous plate could
be produced. (Figure 7)

Longitudinal view

72 m (64 m)

16000 kN
Grand view

Transverse view 2*HE1000M

5
m

Figure 7 – Prestressed concrete continuous plate

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Cutting this plate, simple ceiling plates are produced. After more than 20 years of
the production of ceiling plates, the producer decided to stop production.
Decomposed steel frame represented a lot of steel pieces. (Figures 8, 9, 10)

Figure 8 – Decomposed steel frame

Figure 9 – Decomposed steel frame – press for the continues application of prestressing
force

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Figure 10 – Decomposed steel frame – transverse beam for the fixation of prestressing cables

They decided to use these steel for the production of a special steel frame for the
production of prestressed concrete bridge beam prefabricates with a span 36 m.
(Figure 11 and 12). The price of the transportation is very high. Equipment for the
production of bridge prefabricates must be movable and arranged close to the
building place.

3*12=36 m

5000 kN HE1000M

2*HE1000M

9000 kN

Figure 11 – Steel frame for the production of prestressed bridge beams

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Figure 12 – Steel frame in the workshop

3. CONCLUSION
Presented results show that the form of 60 m length is sufficiently stable in terms
of both horizontal and vertical deformations. Undesirable phenomenon of horizontal
deformation might occur in the form with length 120 m. Presented results show an
idea how to evaluate the friction effects in case of the stability of a beam. Initial
imperfections play the crucial role in this problem. Even if we do not have enough
information about these imperfections anyhow this idea helped to solve the problem
in practice.
Second part of this article shows the design and production of special heavy frame
for production of bridge prestressed prefabricates using “the second hand” steel parts.

ACKNOWLEDGEMENTS
This work has been undertaken as a part of a project founded by the Slovak
Scientific Grand Agency. Project No. 1/0272/15.

REFERENCES
[1] Bažant, Z. P. – Cedolin, L.: Stability of Structures. Oxford University Press.
New York-Oxford. 1991.
[2] Ravinger, J.: Stability & Vibration. STU Btatislava. 2012.
[3] Ravinger, J.: Vibration of an Imperfect Thin-walled Panel. Part 1: Theory and
Illustrative Examples. Part 2: Numerical Results and Experiment, Thin-Walled
Structures, 1994, Vol. 19, No 1, 1-36.
[4] Partov, D. – Petkov, M.: A Survay of Temporary Steel Structures Used for
Strengthening of a Great Excavation for New Metro in Sofia. Proceeding 10-th
Int. Scientific Conf. VSU 2010, Sofia. Vol 1. II-50-58.

[150]
CONTEMPORARY CONSTRUCTION MATERIALS
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Jelena BIJELJIĆ
Milan PROTIĆ2
Saša MARINKOVIĆ3
Nenad RISTIĆ4
Zoran GRDIĆ5

MECHANICAL PROPERTIES OF STEEL – POLYPROPYLENE

HYBRID FIBER – REINFORCED CONCRETE
Abstract: Fiber reinforcement of concrete prevents the onset and propagation of the cracks, increases its
toughness and improves other mechanical characteristics. The paper presents the research of mechanical
properties of hybrid fiber reinforced concretes with steel and polypropylene fibers. For the testing
purposes were used steel fibers with hooked ends and monofilament polypropylene fibers, and a total of
6 batches of concrete were made. The testing results demonstrated that the concretes with addition of
0,4% of steel fibers and 0,1% of polypropylene fibers (S4P1) have better mechanical characteristics in
comparison to other concretes.

Кey words: concrete, hybrid fiber-reinforced, steel fibers, polypropylene fibers, mechanical properties.

MEHANIČKE KARAKTERISTIKE HIBRID MIKROARMIRANIH

BETONA SA ČELIČNIM I POLIPROPILENSKIM VLAKNIMA
Rezime: Mikroarmiranjem betona sprečava se pojava nastanka i propagacije prslina, povećava se
njegova žilavost i poboljšavaju ostale mehaničke karakteristike. U radu je prikazano istraživanje
mehaničkih svojstava hibridno mikroarmiranih betona sa čeličnim i polipropilenskim vlaknima. Za
potrebe istraživanja korišćena su čelična vlakna sa ojačanim krajevima i monofilamentna polipropilenska
vlakna, a napravljeno je ukupno 6 serija betona. Rezultati ispitivanja pokazuju da betoni sa dodatkom
0,4% čeličnih i 0,1% polipropilenskih vlakana (S4P1) imaju bolje mehaničke karakteristike u odnosu na
ostale betone.

Ključne reči: beton, hibridno mikroarmiranje, čelična vlakna, polipropilenska vlakna, mehanička
svojstva.

1
PhD student, University of Nis, Faculty of Civil Engineering and Architecture, Serbia, jelena.bijelic@hotmail.com
2
M.Sc., Ph.D. student , College of Applied Technical Sciences Nis, Serbia, protic.milan@ymail.com
3
Assist. M.Sc., University of Kragujevac, Faculty of Mechanical and Civil Engineering, Serbia,
marinkovic.s@mfkv.kg.ac.rs
4
Assist. Ph.D., University of Nis, Faculty of Civil Engineering and Architecture, Serbia, nenad.ristic@gaf.ni.ac.rs
5
Prof. Ph.D., University of Nis, Faculty of Civil Engineering and Architecture, Serbia, zoran.grdic@gaf.ni.ac.rs

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1. INTRODUCTION
Hybrid fiber reinforced concretes represent a relatively new building material
which consists of concrete with fine fractions of aggregate and fibers of various
materials representing reinforcement of the concrete. In order to make this concrete
usable in engineering structures, it is necessary to predict its mechanical
characteristics, strength and durability so that the failure risk of these structures could
be assessed. In the numerous research [1-3] different types of reinforcement fibers
were used (straight and curved steel fibers, carbon, polymer fibers etc) which can
generally be divided into metallic and non-metallic fibers. Addition of various
combinations of these fibers to concrete and their impact on mechanical and
dynamical properties was examined [4].
Crack control plays a crucial role in the performance life of concrete construction.
This is because the settlement and shrinkage cracks may pass through fresh concrete,
thus forming planes of weakness and lowering the integrity of the concrete
constructions. Further, the service loads may overstress hardened concrete for
cracking, leading from cracking to substantial failure in concrete. Concerning the
crack control, the incorporating of discrete fibers into the vulnerable concrete is
useful and effective. The resulting fiber-reinforced concrete exhibits satisfactory
resistance to crack formation and propagation. Because no single type of fibers can
universally build into the concrete the resistance, the hybrid fiber system emerged as
another resistance builder. It has been shown [5] that by using the concept of
hybridization with two different fibers incorporated in a common cement matrix, the
hybrid composite can offer more attractive engineering properties because the
presence of one fiber enables the more efficient utilization of the potential properties
of the other fiber. Most often those are combinations of metallic and non-metallic
fibers, and in this experiment, combination of steel and polypropylene fibers was
used, which according to the research conducted by Sivakumur [1] provides the best
characteristics to concrete, in comparison with the combinations of steel fibers with
glass or polyester fibers.
In a fresh concrete mix with hybrid fiber reinforcement, internal stresses develop
during settlement and shrinkage and they are directed towards the millions of fine
polypropylene fibers distributed in concrete in all directions, and this way, the onset
of micro-cracks is prevented. In the hardened loaded concrete, the polypropylene
fibers with a small modulus of elasticity are inefficient for crack control, but then the
inserted steel fibers with the high modulus of elasticity become prominent. Steel
fibers act like micro-bridges in concrete, transferring stresses from one side of a crack
onto the other, in this way reducing the concentration of stresses at the tops of cracks,
which prevents their further development [6].
Presence of a considerable quantity of steel fibers in concrete reduces the
workability of concrete which leads to the irregular consolidation of fresh concrete,
which leads to the onset of micro-cavities and other deficiencies. By replacing the
steel fibers with hybrid steel-propylene combination, the density of fresh concrete

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mix is reduced and its workability is increased while the polypropylene fibers
partially negate the undesirable effects of steel fibers [1].
The hybrid combination of metallic and non-metallic fibres can offer potential
advantages in improving concrete properties as well as reducing the overall cost of
concrete production considering that steel fibers are the most expensive. It is
important to have a combination of low and high modulus fibres to arrest the micro
and macro cracks, respectively. Another beneficial combination of fibres is that of
long and short fibres. Once again, different lengths of fibres would control different
scales of cracking [1].
According to Qian [7] the longer steel fibers significantly improve the concrete
strengths. The curved steel fibers showed the best results owing to their increased
lengths, higher tensile strength and better cohesion. In the research of Sivakumur [1]
where the amount of fiber reinforcement was maintained constant at 0,5% of the total
volume, steel-polypropylene combination with 0,12% polypropylene fibers and
0,38% steel fibers showed the best results in comparison with the concrete reinforced
with steel fibers only.
The paper presents the research of mechanical properties of hybrid fiber reinforced
concretes with steel and polypropylene fibers. The total amount of fibers of all the
fiber reinforced concretes was the same (0,5% in relation to the volume), while the
ratio between the steel and polypropylene fibers was varied.

2. EXPERIMENTAL RESEARCH
2.1. Materials used in the experiment
The reference concrete was produced with the Portland cement CEM I 52.5 R. For
preparation of concrete, the aggregate obtained by mixing three fractions 0/4, 4/8 and
8/16 mm from the river aggregate of the Southern Morava River was used. Particle
size distribution of the individual fractions is presented in the figure 1.

Figure 1 – Particle size distribution of the individual fractions

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Two types of fibers were used for production of micro-reinforced concretes:

polypropylene fibers FIBRILs S120 produced by “Motvoz” Grosuplje from Slovenia
and steel fibers ZS/N 0.5x30 mm produced by “Spajic” d.o.o. Company Negotin from
Serbia. The steel ZS/N 0.5x30 mm belong to the group of hook ended fibers, while
the polypropylene fibers of FIBRILs S120 type belong to the group of monofilament
fibers of circular cross sections and smooth surface. The fibers characteristics are
given in the table 1. Also used was water reducer SIKA Viscocrete 3070.
Таble 1- Characteristics of polypropylene and steel fibers
Polypropylene fibers Steel fibers
FIBRILs S120 ZS/N 0.5x30 mm
Characteristic
(monofilament fibers) (hook ended fibers)
Fiber length 12 mm 30 mm
Diameter (equivalent) 0.037 mm 0.50 mm
Aspect ratio 324 60
Tensile strength 300,7±31,7 N/mm2 1100±165 N/mm2

2.2. Concrete mixture composition

Six mixtures for testing fresh and hardened concrete properties were made. The
reference mixture was made by the river aggregate, cement, water and water reducer,
marked with E. The mixture marked S5 was made with addition of steel hook ended
fibers ZS/N 0.5x30 mm, in the amount of 0,5% of the volume; P5 with addition of
0,5% polypropylene monofilament fibers FIBRILs S120, in the amount of 0,5% of
the volume; S4P1 with addition of 0,4% of steel and 0,1% of polypropylene fibers;
S3P2 with addition of 0,3% of steel and 0,2% of polypropylene fibers and S2P3 with
addition of 0,2% of steel and 0,3% of polypropylene fibers.
Таble 2- Composition of 1m3 of concrete mixtures used in the experiment
Aggregate Sika VSC Polypropylene fibers Steel fibers
Series of Cement Water
0/4 mm 4/8 mm 8/16 mm 3070 Fibrils S 120 ZS/N 0.5x30
specimen
3 3 3 3 3 3 3
kg/m kg/m kg/m kg/m kg/m kg/m kg/m kg/m3
E 792 440 528 400 180,0 2,40 - -
S5 782 435 522 396 178,2 2,38 - 39,25
P5 787 437 524 397 178,7 2,38 4,55 -
S4P1 783 435 522 395 177,8 2,37 0,91 31,40
S3P2 783 436 523 396 178,2 2,38 1,82 23,55
S2P3 784 436 523 396 178,2 2,38 2,73 15,70

The particle size distribution of basic fractions of aggregates was the same for all
the mixtures (0/4 mm – 45%, 4/8 – 25% and 8/16mm – 30%). The mixtures were
made with the same water /cement ratio (mw/ mc = 0.45) and with the same aggregate
/cement ratio (ma/ mc = 4.40). All mixtures were made with addition of the

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superplasticizer in the amount of 0,6% of the mass of cement. The compositions of

the concrete mixtures are given in the table 2.
2.3. The types of examination in experiment
The consistency was measured on the fresh concrete by the slump test according
to SRPS ISO 4109:1997, the bulk density according to SRPS ISO 6276:1997 and air
content of freshly mixed concrete according to SRPS ISO 4848:1999. The
compressive strength and bulk density of hardened concrete were tested on the cubes
with 150 mm sides according to SRPS ISO 4012:2000, the flexural strength on the
prisms with dimensions 100 x 100 x 400 mm according to SRPS ISO 4013:2000, the
tensile splitting strength on cylindrical cores Ø150×300 mm according to SRPS ISO
4108:2000. The bond strength by “Pull-off test” was tested on the slabs with
dimensions 200 x 200 x 50 mm according to SRPS EN 1542:2010. The compressive
strength was tested on 2, 7 and 28 days old specimens, while the other mechanical
properties were tested on 28 days old specimens.

3. RESULTS OF EXPERIMENTAL RESEARCH

The tests results of fresh and hardened concrete are presented in the tables 3 and 4.
Таble 3- Characteristics of concrete in fresh state
Series of Slump Air content Density
specimen [mm] [%] [kg/m3]
E 110 3,0 2342
S5 100 3,6 2356
P5 30 4,8 2330
S4P1 90 3,7 2348
S3P2 75 3,9 2344
S2P3 55 4,2 2338

Таble 4- Characteristics of concrete in hardened state

Compressive strength [MPa] Flexural Splitting tensile Bond strength

Series of Density strength strength by Pull-off
specimen [kg/m3]
2 days 7 days 28 days [MPa] [MPa] [MPa]

E 2338 39,22 50,67 58,22 5,69 4,34 4,71

S5 2350 40,90 48,14 61,52 6,70 5,11 5,26
P5 2328 43,41 50,00 59,89 6,46 4,94 5,42
S4P1 2342 41,22 48,86 62,18 6,95 5,24 5,56
S3P2 2341 42,01 47,53 60,75 6,55 5,06 5,34
S2P3 2333 42,32 49,44 59,33 6,35 4,85 5,20

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4. DISCUSION OF RESULTS AND CONCLUSION

As it can be observed in the table 3, when testing the consistency of concrete
mixes using the Abrams cone slump test, the highest slump was recorded for the
reference mix with no addition of microfibers, while the mixture reinforced with only
polypropylene fibers had the lowest slump. The mixture reinforced with steel fibers
only had a negligibly lower slump than the reference concrete. The slump of values of
hybrid fiber reinforced mixes ranged between the values of the mixtures reinforced
with polypropylene only or with steel only fibers. Microfibers contribute to the
compactness of fresh concrete mixture, whereby the compactness depends on the type
of used fibers and their characteristics. (aspect ratio, fiber length, diameter). In the
concrete case, the number of polypropylene fibers in a volume unit was considerably
higher than the steel ones, so the workability and placeability of fiber reinforced
concrete mixtures with polypropylene fibers is lower in comparison with the mixture
with steel fibers and reference mixture. It is logical that with the reduction of the
amount of polypropylene fibers the value of the slump of hybrid fiber reinforced
mixtures increases.
Based on the test results provided in table 3, it can be concluded that the addition
of polypropylene and steel fibers had an influence on the variation of air content in
fresh concrete, which was increased. This effect was more prominent in case when
higher quantity of fibers is added (regardless of their kind and type). By comparing
the obtained results, it can be concluded that the concretes reinforced by the only
polypropylene fibers have higher air content in comparison to the concretes with only
steel fibers. This is logical regarding that the number of polypropylene fibers in a unit
of volume is considerably higher in respect to the steel fibers. Also, it can be easily
observed that with the reduction of the amount of polypropylene fibers in hybrid fiber
reinforced mixtures, the content of entrained air in fresh concrete is reduced.
The addition of fibers, had a lower effect on the variation of density of compacted
fresh concrete, table 3. In the case of the mixture with only polypropylene fibers, this
is to be expected regarding the small quantity of fibers (0,5% of the volume or 4,55
kg/m3), as well as a small contribution of these fibers to the total amount of air
content in fresh concrete mixture (table 3). The addition of steel fibers contributed to
small increase of density of compacted fresh concrete, regarding the dosage of these
fibers, amounting to 39,25 kg/m3 of concrete. It is logical that the mixture with the
addition of steel fibers only has the highest density, and the mixture with the addition
of polypropylene fibers only has the lowest density. The density of hybrid fiber
reinforced mixtures ranges between these two values. Also, the value of the density of
fresh concrete mix is influenced by the density of polypropylene (910 kg/m3) and
steel fibers (7850 kg/m3).
Considering the types of concrete mixes which were analyzed in this research, the
value of compressive strength and its increase in time was affected by the type and
geometry of used fibers, as well as the ratio of steel and polypropylene fibers in the
mixture. The results presented in the table 4, regarding the usage of fiber
reinforcement confirm the known fact that the addition of fibers, primarily the

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polypropylene ones, does not have a notable contribution in terms of increase of

compressive strength of concrete. Namely, it is possible to considerably increase
compressive strength of the concrete reinforced with steel fibers, but only in the case
of a higher dosage of fibers (added steel fibers exceeding 0,5% in volume). Since in
this research, the steel fibers were added to the maximum amount of 39,25 kg/m3, i.e.
0,5% of volume, it was logical to expect a small increase of compressive strength, in
comparison with the reference concrete. In terms of concretes reinforced with
polypropylene fibers, the increase of compressive strength is less prominent, which is
explained mostly by the excess of entrained air during mixing and placement of
concrete, table 3. By analyzing the results of compressive strength of 2 days old
samples, table 4, it can be observed that there is a considerable contribution of fibers,
primarily propylene ones, to the increase of strengths, which is logical because in that
period of hardening the cement rock is the main factor of concrete strength. In the 7
days old samples, there is a decrease in compressive strength of fiber reinforced
concretes in comparison with the reference concrete, while at the age of 28 days, fiber
reinforced concretes have slightly higher compressive strengths in comparison with
the reference concrete. At the age of 28 days, the highest value of compressive
strength was recorded for the mixture marked as S4P1 which is for 6,8% more in
comparison with the reference concrete. The increase of compressive strength of the
mixture marked S5 amounts to 5,7%, of the mixture marked S3P2 it amounts to 4,3%,
of the mixture marked P5 it amounts to 2,9% and of the mixture marked S2P3 it
amounts to 1,9% in comparison with the reference concrete.
As it is already known, the addition of fibers to the concrete should primarily
provide higher tensile strength of concrete, as it was confirmed in this paper based on
the test results presented in table 4. In a similar way as in case of the compressive
strength, the flexural strength is influenced by type and geometry of applied fibers, as
well as ratio of steel and polypropylene fibers in concrete. The mixture marked S4P1
had the highest value of flexural strength which was for 22,1% higher than the
reference concrete. The increase of the flexural strength of the mixture marked S5
was 17,8%, of the mixture S3P2 it was 15,1%, of the mixture P5 it was 13,5% and of
the mixture S2P3 it was 11,6% in comparison with the reference concrete.
By analyzing the test results of the splitting tensile strength in table 4, it can be
concluded that fiber reinforcing, regardles of the type of fiber, contributed to
improvement of this mechanical characteristic of concrete. The highest value of
splitting tensile strength was achieved by the mixture marked S4P1 which is for
20,7% higher than the reference concrete. The increase of splitting tensile strength of
the mixture marked S5 is 17,7%, of the mixture marked S3P2 it is 16,6%, of the
mixture marked P5 it is 13,8% and of the mixture marked S2P3 11,8% in comparison
with the reference concrete.
Also, by analyzing the test results from table 4, it can be concluded that both
polypropylene and steel fibers, as well as their combination contributed to the
increase of bond strength by „Pull-off“ test. The highest value of bond strength by
„Pull-off“ test was achieved by the mixture marked S4P1 which is for 18,0% higher

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in respect to the reference concrete. The increase of bond strength by „Pull-off“ test
of the mixture marked S5 is 15,1%, of the mixture marked S3P2 it is 13,4%, the
mixture marked P5 it is 11,7% and the mixture marked S2P3 it is 10,4% in
comparison with the reference concrete. It should be emphasized that the value of
bond strength by „Pull-off“ test was to great extent affected by the arrangement of
reinforcement fibers within the concrete composite. Namely, since the polypropylene
fibers are smaller and more numerous in comparison with the steel ones, the
distribution of these fibers within the concrete composite is more homogenous in
terms of quantity and direction. It is particularly important for the surface parts of the
concrete sample (in practice, it is a structural concrete element) on which the value of
bond strength by „Pull-off“ test is tested. It is logical that higher bond strengths by
„Pull-off“ tests will be obtained, if a larger number of fibers in the surface zone of
concrete are oriented in the direction or at a small angle to the direction of pull-off
force action.
In general, the addition of steel fibers to the concrete, in terms of mechanical
characterstics provides a higher contribution than the polypropylene fibers. In this
research it was demonstrated that replacement of 20% of steel fibers by the propylene
ones in the total amount of 0,1% in relation to the volume contributes to a negligible
improvement of mechanical characteristics of concrete. The explanation lies in the
superposition of the positive effects of addition of polypropylene fibers exhibited in
the early phase of concrete hardening on one hand, and on the other hand in the
positive effects of addition of steel fibers exhibited in the late phase of concrete
hardening.

ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry for Science and Technology, Republic of Serbia. This support is
gratefully acknowledged.

REFERENCES
[1] Sivakumur A., Santhanam M. 2007. Mechanical properties of high strength concrete
reinforced with metalic and non-metalic fibres. Cement&Concrete Composites.29:603-8.
[2] Yew M. K., Othman I., Yew M. C., Yeo S. H., Mahmud H. B. 2011. Strength properties
of hybrid nylon-steel and polypropylene-steel fibre-reinforced high strength concrete at
low volume fraction. International Journal of the Physical Sciences. 33: 7584-7588.
[3] Kwan W. H., Ramli M., Cheah C. B. 2014. Flexural strength and impact resistance study
of fibre reinforced concrete in simulated aggressive environment. Construction and
Building Materials. 63: 62-71.

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[4] Guan X., Liu X., Jia X., Yuan Y., Cui J., Mang H. A. 2105. A stochastic multiscale
model for predicting mechanical properties of fiber reinforced concrete. International
Journal of Solids and Structures. 56-57: 280-289.
[5] Yao W., Li J., Wu K. 2003. Mechanical properties of hybrid fiber-reinforced concrete at
low fiber volume fraction. Cement and Concrete Research. 33: 27-30.
[6] Song P. S., Wu J. C., Hwang S., Sheu B. C. 2005. Statistical analysis of impact strength
and strength reliability of steel–polypropylene hybrid fiber-reinforced concrete.
Construction and Building Materials. 19: 1-9.
[7] Qian C., Stroeven P. 2000. Fracture properties of concrete reinforced with steel-
polypropylene hybrid fibres. Cement & Concrete Composites. 22: 343-351.

[160]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Vesna BULATOVIĆ
Mirjana MALEŠEV2
Miroslava RADEKA3
Vlastimir RADONJANIN4
Ivan LUKIĆ5
ANALYSIS OF SULPHATE RESISTANCE OF CONCRETE USING
NATRIUM AND MAGNESIUM SULFATE
Abstract: This paper presents some results of the experimental investigation on the sulfate resistance of
concrete immersed in 5% Na2SO4 and 5% MgSO4 solutions for periods of 3 and 6 months. The effect of
water-cement ratio (w/c) and cement type (ordinary and sulfate resistance with granulated blastfurnace
slag) were investigated. The experimental results of compressive strength showed that the effect of w/c
ratio was more pronounced for the ordinary cement, while the sulfate resistance cement was less affected
by an increase in the w/c ratio. It was also observed that the period of 3 months is not enough for making
some conclusions about resistance of concrete on sulfate attack in these conditions.

Key words: concrete, sodium sulfate, magnesium sulfate, blast furnace slag.

ANALIZA SULFATNE OTPORNOST BETONA POMOĆU NATRIJUM

I MAGNEZIJUM SULFATA
Rezime: U radu je prikazan deo rezultata eksperimentalnog istraživanja sulfatne otpornosti betona
potopljenih u rastvore Na2SO4 i MgSO4 koncentracije 5%, za period od 3 i 6 meseci. Ispitivani su uticaji
vodocementnog faktora i vrste cementa (običan i sulfatno-otporni sa dodatkom granulisane zgure visokih
peći). Eksperimentalni rezultati čvrtoće pri pritisku pokazali su da je uticaj vodocementnog faktora viši
kod betona spravljenih sa običnim portland cementom nego kod onih sa sulfatno-otpornim cementom.
Takođe, je uoperiod od 3 meseca nije dovoljan za donošenje zaključaka o otpornosti betona na delovanje
sulfata pod ovim uslovima.

Ključne reči: beton, natrijum sulfat, magnezijum sulfat, granulisana zgura visokih peći.

1
MSc, Assistant, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, e-mail: vesnam@uns.ac.rs
2
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, e-mail: miram@uns.ac.rs
3
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, e-mail: mirka@uns.ac.rs
4
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, e-mail: radonv@uns.ac.rs
5
PhD, Assistant Professor, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering
and Geodesy, e-mail: lookic@uns.ac.rs

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1. INTRODUCTION
Sulfate attack is one the most aggressive and the most complex durability
problems associated with concrete. The sulfate attack of concrete leads to expansion,
cracking, and deterioration of many civil engineering structures exposed to sulfate
environment such as piers, bridges, foundations, concrete pipes, etc. The sulfate ions
in solution, which come from the soil, groundwater, rivers, seawater, cooling towers,
industrial wastes, are found in combination with other ions such as sodium,
potassium, magnesium and calcium ions [1].
Sulfate attack "is a complex sequence of physical and chemical processes resulting
in chemical and physical (micro-structural) modifications of the cement paste matrix",
leading to the "loss of mechanical and physical properties of a structure" [2]. Or,
sulfate attack can be defined "as the deterioration of concrete as a result of physical-
chemical interactions between the minerals in hydrated portland cement paste and
sulfate from the environment" [3].
Sulfates can enter concrete in solution form from the external environment, or they
may be mixed into concrete. They occur naturally and are used in industry. Concrete
resistance to sulfate attack has been studied worldwide in order to explain the
mechanisms of sulfate attack and to evaluate the durability of concrete in the sulfate-
rich environments. Although sulfate attack on concrete has been studied many years,
some details of the mechanisms of attack are still not know, and concrete failure still
occurs. The use of new and supplementary cementing materials in recent decades,
while enhancing some aspects of concrete durability, makes the picture of sulfate
resistance more complicated because of the varied effects ranging from beneficial to
deleterious. While there is insufficient understanding of the mechanisms of attack, it
is difficult to devise suitable test procedures, determine adequate performance criteria
and to interpret results satisfactorily [3]. The major problem in assessing materials is
that the form of attack in sulfate environments is variable and the mechanistic theory
is complex and uncertain [4]. The confounding effects of cement composition,
concrete mixture design, chemical and mineral admixtures, concrete placing and
curing procedures, and complicated (often variable) environmental exposures make it
quite difficult to sort out key factors in the process of sulfate attack [2].
Most testing is undertaken on mortar or cement paste samples, as concrete
introduces additional variables and makes testing more labour intensive. However,
penetrability plays a major part in the deterioration process, particularly penetration
of the sulfate solution around the interface layer between aggregate and paste. This
layer does not exist in mortars but does become a major factor in real concrete [4].
Sulfate attack on cement mortars and concrete leads to the conversion of the
hydration products of cement (calcium hydroxide and calcium aluminate hydrate) to
ettringite, gypsum, an other phases, and also to the destabilization of the calcium
silicate hydrate (C-S-H) like providing primary strength. This leads to softening,
expansion and cracking of concrete 5. The actual reactions process depends on the

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type of sulfate salt and reaction products, and especially on the solubility of each
constituent-rich, in turn, is a function of the pH value of the solution 3.
In the case of sodium sulfate (Na2SO4) two reactions are main, the reaction of
Na2SO4 and Ca(OH)2 to form gypsum and the reaction of the formed gypsum with
calcium aluminate hydrates to form ettringite. The expansion resulting from sulfate
attack is generally attributed to the formation of these two compounds (gypsum and
ettringite), although there is some controversy surrounding the exact mechanisms
causing expansion [5]. When the attacking solution contains magnesium ion, such as
in magnesium sulfate (MgSO4), it reacts with all cement compounds, including CSH,
thus decomposing cement, and subsequent forming gypsum and ettringite. Concrete
deterioration due to MgSO4 attack was attributed to the decalcification of C-S-H to
form M-S-H, the formation of magnesium hydroxide (brucite) as well as the
expansion caused by the formation of expansive salts.
The extent to which concrete is affected by sulfates depends on several factors:
porosity and permeability, water to cement (w/c) ratio, type of cement and
composition, exposure conditions and the environment. The chemistry of the cement
and the permeability of the concrete are the easiest way to control the resistance of a
given concrete to sulfate attack. Lower w/c ratio and/or mineral additions (blast-
furnace slag, fly ash, silica fume) as a partial replacement of ordinary cement are
recommended. On this way, permeability and the amount of CH and C3A are reduced.
CH and C3A are known to be responsible for the formation of ettringite and gypsum,
which can be considered as the principal cause of deterioration 6.

2. EXPERIMENTAL INVESTIGATION
Deterioration due to sulfate attack has been evaluated in a variety of tests and
procedures that include visual assessment, wear rating, loss of mass, hardness,
compressive strength, determining modul of elasticity, expansion, determining
permeability and porosity, microstructural analysis etc. Tests used in research
laboratories vary with respect to sulfate solution, exposure duration, temperature,
specimen size, deterioration assessment, etc.
In order to investigate the effects of two parameters (w/c ratio and cement
composition) on sulfate resistance of concrete, ordinary (CEM I) and sulfate resisting
(CEM III) cement were used to prepare eight concrete mixture with two different w/c
ratios, above and below the usually assumed percolation treshold of 0,4 and different
type of coarse aggregate (natural and recycle concrete). These concrete specimens
were immersed in a Na2SO4 and MgSO4 solutions of concentration of 5% by weight
and were tested periodically. The solutions were renewed every 3 months. Control
specimens were immersed in lime-saturated water. The all containers were covered to
minimise carbonation.
This paper presents results of compressive strength and capillary water absorption
of four concrete mixtures with natural aggregate which have been immersed in sulfate
solutions 3 and 6 months.

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2.1. Component materials and the composition of the tested concrete mixtures
For experimental investigation of influence of different water to cement ratio and
different type of cement on the sulfate resistance of concrete, the following
component materials were used:
3
 Portland cement CEM I 42,5R (Lafarge-BFC Serbia, γsc = 3100kg/m ),
 Low heat/Sulfate resistance cement CEM III/B 32,5N LH/SR (Lafarge-BFC
Serbia, γsc = 2650kg/m3),
3
 Fine aggregate (natural aggregate, river Drina, 0/4 mm, γs = 2650kg/m ),
 Coarse aggregate (natural aggregate, river Drina, 4/8 and 8/16mm,
γs = 2650 kg/m3),
3
 HRWRA 1 ("Sika ViscoCrete 3070", "Sika"- Switzerland, γs = 1090kg/m ),
3
 HRWRA 2 ("Sika ViscoCrete 5500MP", "Sika"- Switzerland, γs = 1100kg/m ),
 Tap water.
Before preparing concrete mixtures, the basic physical properties of Portland
cement and Sulfate resistance cement were tested. They have been tested according to
standards EN 196-1, EN 196-3 and EN 196-6. Based on these results, it was
concluded that the cements meets the criteria for CEM I 42,5R and CEM III 32,5N
LH/SR according to EN 197-1 and the appropriate National Code
Concrete mix proportions were determined based on the following assumptions:
 Absolute volume of cement and water were around 0.3 m3,
 Maximum grain size was 16 mm,
 Two w/c ratios were used in this study: 0.38 and 0.55,
 Fuller‘s granulometric curve of a mixture of aggregates
 The amount of super-plasticizer was based on the need to achieve the required
consistency,
 Air content was approximately 2%.
Based on these conditions, quantities of component materials for 1m3 of concrete
mix were calculated. Designed quantities of component materials are shown in kg/m3
in Table 1.
Table 1. Marks and mix proportions of concrete in kg/m3

Concrete mc mc mspk mspk

mv ma,s ma,k w/c
type CEM I CEM III VSC3077 VSC5500

NPC1 350 - 192.5 930 858 - - 0.55

NPC2 423 - 161 936 864 5.9 - 0.38
NMC1 - 338 186 936 864 0.7 - 0.55
NMC2 - 416 158 937 865 - 2.5 0.38

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2.2. Methods and testing results

The following types of concrete specimens were prepared from each mixture for
testing compressive strength and capillary water absorption:
 150mm cubes for compressive strength at age of 28 days
 100mm diameter x 100mm height cylinders for compressive strength at 3 and 6
months after immersing the specimens into the sulfate solutions
 150mmx150mmx75mm slabs for testing capillary water absorption.
After casting and finishing, the molds for cubes and slabs were covered with
plastic sheets and stored for 24h in a moist room, but cylinders stayed in closed cans
for 7 days. After the initial curing period (one day or seven days), specimens were
demoulded and cured in lime-saturated water at 20±2°C until 42 days (from preparing
mixture) after that they were transferred to plastic containers containing a sulfate
solutions or stayed there (control specimens). Specimens from each mixture have first
letter in label "E" if they are in lime-saturated water solution, "N" if they are in
5%Na2SO4 solution or "M" if they are in 5%MgSO4 solution stored. Testing of
compressive strength and capillary water absorption were performed on specimens
before were immersed in sulfate solutions and at 3 and 6 months holding there.
2.2.1. Compressive strength
Samples for the testing of compressive strength were cured in lime-saturated water
or 5%Na2SO4 or 5%MgSO4 solution to the anticipated age. The compressive strength
computed as an average of three specimens are presented in Table 2.
Таble 2 - Compressive strength of specimens at 28 days, 3 and 6 months after immersing in
solutions
Concrete Concrete
28 days 3 months 6 months 28 days 3 months 6 months
type type
ENPC1 54.4 55.1 ENMC1 45.3 46.4
NNPC1 46.3 55.8 42.9 NNMC1 31.8 43.4 46.1
MNPC1 56.3 52.3 MNMC1 43.3 42.5
ENPC2 79.3 87.9 ENMC2 70.0 71.4
NNPC2 72.5 80.7 79.7 NNMC2 52.8 62.6 64.7
MNPC2 81.1 71.5 MNMC2 76.0 74.7
2.2.2. Capillary water absorption
Determination of capillary water absorption were done by procedure given in
SRPS U.M8.300. Before testing, samples were conditioned at standard laboratory air
temperature and humidity for 14 days. Surface area subjected to water was cca
225cm2. After weighing the dry specimens, they were put on rods in a water tank in
such way that they were immersed for no more than 5 mm. To obtain unidirectional
flow, side surface of concrete specimens were covered with a waterproofing
membrane. Measurements were conducted after 1, 5, 15, 30 minutes, 1, 4, 9, 25 and
49 hours. The results were expressed as water absorption in kg/m2 and presented
values are average of three specimens.

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2.3. Discussion
2.3.1. Compressive strength
Concrete compressive strength was tested on 15cm cubes and on 100mmx
100mm height cylinders, as said earlier. The results of concrete compressive strength
at the age of 3 and 6 months of exposure in magnesium sulfate, sodium sulfate and
lime-saturated water as well as the strength prior to exposure to sulfate solutions are
shown in Table 2 and in Figure 1.
As it can be seen on presented diagrams (Figure 2) the type of cement and water to
cement ratio have significant effect on concrete compressive strength. Concrete
mixtures made with CEM I 42.5R have markedly higher strength than corresponding
concrete mixtures with CEM III 32.5N LH/SR (with same v/c ratio, and at the same
age) regardless of the type of exposure ( Na2SO4, MgSO4, or lime-saturated water).
The similar conclusion can be made regarding to water to cement ratio.
ENPC1/NNPC1/MNPC1 ENPC2/NNPC2/MNPC2
90 90
Compressive strength [MPa]

Compressive strength [MPa]

80 80
70 70
60 60
ENPC1 ENPC2
50 50
NNPC1 NNPC2
40 40
MNPC1 MNPC2
30 30
20 20
10 10
0 0
28 days 3 months 6 months 28 days 3 months 6 months
Age Age

ENMC1/NNMC1/MNMC1 ENMC2/NNMC2/MNMC2
90 90
Compressive strength [MPa]
Compressive strength [MPa]

80 80
70 70
60 60
50 ENMC1 50
ENMC2
40 NNMC1 40
30 MNMC1 30 NNMC2
20 20
MNMC2
10 10
0 0
28 days 3 months 6 months 28 days 3 months 6 months
Age Age

Figure 1 – Compressive strength of concrete specimens immersed in lime-saturated

water and sulfat solutions
By comparing obtained values of compressive strength of samples that were
exposure to Na2SO4 or MgSO4 solutions during period of 3 and 6 months with
compressive strength of referent samples at the moment of starting exposure
procedure (Table 2) it can be concluded:
 All concrete mixtures showed an increase in compressive strength at the age of 3
months of exposure to sulfate solutions;
 Most of concrete mixtures showed an increase in compressive strength at the age
of 6 months of exposure to sulfate solutions,
 Concrete mixture with CEM I and w/c= 0.55 showed decrease in compressive
strength of 9% after 6 months of exposure to Na2SO4 solution.

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These changes of strength were additionally evaluated in relation to

corresponding strength of referent specimens (Figure 2).
ENPC1/NNPC1/MNPC1 ENPC2/NNPC2/MNPC2
1,1 1,1
Relative compressive strength

Relative compressive strength

1,05 1,05
1 1
0,95 0,95
ENPC1 ENPC2
0,9 0,9 NNPC2
NNPC1
0,85 MNPC1 0,85 MNPC2
0,8 0,8
0,75 0,75
0,7 0,7
0 3 6 0 3 6
Period of exposure, month Period of exposure, month

ENMC1/NNMC1/MNMC1 ENMC2/NNMC2/MNMC2
1,1 1,1
Relative compressive strength

Relative compressive strength

1,05 1,05
1 1
0,95 0,95
ENMC1 ENMC2
0,9 0,9
NNMC1 NNMC2
0,85 0,85 MNMC2
MNMC1
0,8 0,8
0,75 0,75
0,7 0,7
0 3 6 0 3 6
Period of exposure, month Period of exposure, month

Figure 2 – Changes of compressive strength of concrete exposure to sulfate solutions in

relation to corresponding strength of control specimens

It is obvious that the concrete mixtures with cement CEM I stored in Na 2SO4 and
MgSO4 solutions did not show any significant difference in compressive strength
compared to lime-saturated water stored samples at the age of 3 months. After 6
months of exposure to different solutions, all specimens showed drop in strength
compared to control specimens (Figure 2). The greatest decrease of compressive
strength (24%) is noticed in concrete with w/c=0.55 which was immersed in 5%
Na2SO4 solution.
The concrete specimens with cement CEM III LH/SR and w/c=0.55, stored in both
sulfate solutions, did not show any significant difference in compressive strength at
the age of 3and 6 months compared to corresponding lime-saturated water stored
samples.
The concrete specimens with cement CEM III LH/SR and w/c=0.38, stored in
Na2SO4 solutions, had decrease of compressive strength up to the 10% at the age of
3and 6 months compared to corresponding lime-saturated water stored samples, while
the samples of the same concrete mixture which were immersed in MgSO4 solution
shoved some increase of compressive strength after 3 and 6 months. This was
possible due to the filling of the pores by the reaction products of sulfate attack.

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2.3.2. Capillary water absorption

Capillary water absorption of concrete was tested on 150mmx150mmx75mm
slabs. Figure 3 shows the change in the kinetics of capillary water absorption of the
tested types of concrete after 3 and 6 months of exposure to sodium and magnesium
solutions.
NPC1 - 3 months NPC1 - 6 months
0,25 ENPC1-3m 0,25 ENPC1-6m
Capillary water absorption [kg/m2]

Capillary water absorption [kg/m2]

NNPC1-3m NNPC1-6m
0,20 MNPC1-3m 0,20 MNPC1-6m

0,15 0,15

0,10 0,10

0,05 0,05

0,00 0,00
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8
Time, (h0.5) Time, (h0.5)

NPC2 - 3 months NPC2 - 6 months

0,25 ENPC2-3m 0,25 ENPC2-6m
Capillary water absorption [kg/m2]

Capillary water absorption [kg/m2]

NNPC2-3m NNPC2-6m
0,20 MNPC2-3m 0,20
MNPC2-6m

0,15 0,15

0,10 0,10

0,05 0,05

0,00 0,00
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8
Time, (h0.5) Time, (h0.5)

NMC1 - 3 months NMC1 - 6 months

0,25 0,25 ENMC1-6m
Capillary water absorption [kg/m2]

Capillary water absorption [kg/m2]

NNMC1-6m
0,20 0,20
MNMC1-6m

0,15 0,15

0,10 0,10
ENMC1-3m
0,05 NNMC1-3m 0,05
MNMC1-3m
0,00 0,00
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8
Time, (h0.5) Time, (h0.5)

NMC2 - 3 months NMC2 - 6 months

0,25 ENMC2-3m 0,25 ENMC2-6m
Capillary water absorption [kg/m2]

Capillary water absorption [kg/m2]

NNMC2-3m NNMC2-6m
0,20 0,20
MNMC2-3m MNMC2-6m

0,15 0,15

0,10 0,10

0,05 0,05

0,00 0,00
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8
Time, (h0.5) Time, (h0.5)

Figure 3 – Capillary water absorption of examined concrete mixtures after 3 and 6 months of
exposure to sodium and magnesium solutions
Due to different physical processes and chemical reactions and products that occur
during immersion in sodium sulfate and magnesium sulfate solutions it is very
difficult to analyze obtained results of capillary water absorption. The smallest

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capillary water absorption has concrete mixture with CEM I and w/c=0.38. The
largest capillary water absorption has concrete mixture with CEM III LH/SR and
w=0.55, as shown in Figure 3. Also, specimens with w/c =0.38 have more uniformly
and close values of capillary water absorption compared to specimens with w/c =0.55,
Figure 4 shows these results of capillary water absorption separated by Na2SO4
and MgSO4 solutions and by duration of immersion.
Na2SO4 - 3 months Na2SO4 - 6 months
0,25 0,25

Capillary water absorption [kg/m2]

Capillary water absorption [kg/m2]

0,20 0,20

0,15 NNPC1-3m 0,15 NNPC1-6m

NNPC2-3m NNPC2-6m
NNMC1-3m NNMC1-6m
0,10 0,10
NNMC2-3m NNMC2-6m

0,05 0,05

0,00 0,00
0 2 4 6 8 0 2 4 6 8
Time, (h0.5) Time, (h0.5)

MgSO4 - 3 months MgSO4 - 6 months

0,25 0,25
Capillary water absorption [kg/m2]
Capillary water absorption [kg/m2]

0,20 0,20

0,15 MNPC1-3m 0,15 MNPC1-6m

MNPC2-3m MNPC2-6m
MNMC1-3m
0,10 0,10 MNMC1-6m
MNMC2-3m
MNMC2-6m

0,05 0,05

0,00 0,00
0 2 4 6 8 10 0 2 4 6 8
Time, (h0.5) Time, (h0.5)

Figure 4 – Capillary water absorption of examined concrete mixtures sepatated by solutios

and duration of immersion

It can be seen that concrete specimens with sulfate resistance cement (CEM III)
have the larger capillary water absorption than specimens with Portland cement for
the same w/c ratio and for corresponding period of exposure to sulfate solutions. A
little deviation from this conclusion can be seen on specimens MNPC1-6 months and
MNMC1-6 months (Figure 4).
By comparing results of capillary water absorption after 3 and 6 months of
immersion in Na2SO4 and in MgSO4 solutions the significant decrease of capillary
water absorption of concrete mixture with CEM III LH/SR and w/c=0.55 can be
noticed (FIG 4). In other concrete mixtures the changes in value of capillary water
absorption are negligible.
The decreasing of w/c ratio caused the reduction in capillary water absorption,
except for specimens immersed in MgSO4 solution at 6 months, as shown in Figure 3
and Figure 4.

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3. CONCLUSION
Based on the performed experimental research and the analysis of obtained results,
the following conclusions are derivate:
 All concrete mixtures showed an increase in compressive strength after 3 months
of exposure to 5% Na2SO4 or 5% MgSO4 solutions. This increase in
compressive strength is almost same to the increase in concrete compressive
strength of samples stored in lime-saturated water up to 3 months. This
conclusion indicates that period of three months of exposure of tested concrete
mixtures to 5% Na2SO4 or 5% MgSO4 solutions is not long enough to cause
sulfate attack.
 After 6 months of exposure to both sulfate solutions, all specimens that contain
CEM I showed decrease of compressive strength. The greatest decrease of
compressive strength (24%) is noticed in concrete with w/c=0.55 which was
immersed in 5% Na2SO4 solution.
 Compressive strength of concrete mixtures made with CEM III LH/SR after 6
months of exposure depend of type of sulfate solution. In case of immersion in
5%Na2SO4, the decrease of concrete compressive strength was up to the 10%,
but in case of immersion in 5% MgSO4 the increase of 10% occurred.
 The type of cement has significant effect on concrete compressive strength. All
concrete mixtures made with CEM I 42.5R have markedly higher compressive
strength than corresponding concrete mixtures with CEM III 32.5N LH/SR. But
higher compressive strength does not provide higher sulfate resistance of
concrete. Concrete mixtures with CEM III 32.5N LH/SR have lower
compressive strength at the moment of exposure, but have smaller reduction of
compressive strength after 6 months of exposure to sulfate solutions compared to
corresponding referent samples.
 The effect of water to cement ratio on sulfate resistance is more pronounced in
concrete mixtures with CEM I cement. Negative influence of higher w/c ratio on
sulfate resistance can be seen in concrete mixture with w/c=0.55 in case of
exposure to Na2SO4 solution.
 Concrete mixtures with smaller w/c ratio (0.38) have more uniformly and close
values of capillary water absorption compared to mixtures with higher w/c ratio
(0.55).
 Concrete mixtures with CEM III LH/SR have the larger capillary water
absorption than mixtures with Portland cement for the same w/c ratio and for
corresponding period of exposure to sulfate solutions
 The decreasing of w/c ratio caused the reduction in capillary water absorption,
except for specimens immersed in MgSO4 solution at 6 months
 Both factors, water to cement ratio and type of cement have visible influence on
values and cinetics of capillary water absorption.

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ACKNOWLEDGEMENTS
The research work reported in this paper is a part of the investigation within the
research project TR 36017 "Utilization of by-products and recycled waste materials in
concrete composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry of Education, Science and Technological Development of the Republic
of Serbia. This support is gratefully acknowledged.

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[3] Xu Aimin, Shayan Ahmad, Baburamani Pud: Test methods for sulfate resistance
of concrete and mechanism of sulfate attack, Review Report 5 (1998)
[4] Chabrelie A., Müler U., Skrivener K.L.: Mechanism of Degradation of Concrete
by External Sulfate Ions under Laboratory and Field Conditions, The 13th
International Congress on the Chemistry of Cement, Madrid, 3rd- 8th July 2011
[5] Santhanam Manu, Cohen Menashi D., Olek Jan: Mechanism of sulfate attack: A
fresh look Part1: Summary of experimental results, Cement and Concrete
Research 32 (2002) 915-921
[6] Sahmaran M., Kasap O., Duru K., Yaman I.O.: Effects of mix composition and
water-cement ratio on the sulfate resistance of blended cements, Cement and
Concrete Composites 29 (2007) 159-167
[7] SRPS EN 196. Methods of testing cement
[8] EN 197-1. Cement - Part 1: Composition, specifications and conformity criteria
for common cements
[9] SRPS U.M8.300. Determination of the capillary water absorption of building
material and coatings
[10] SRPS ISO 4012. Concrete - Determination of compressive strength of test
specimens
[11] SRPS EN 206-1. Concrete: Specification, performance, production & conformity

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UDK: 691
1
Iva DESPOTOVIĆ
Bojan MILOŠEVIĆ2

THE INFLUENCE OF RECYCLED CONCRETE AGGREGATE ON

THE PROPERTIES OF SELF – COMPACTING CONCRETE
Abstract: In the last years, due to the environmental protection and sustainable development
requirements becoming stricter and broader, a large number of researches worldwide has been conducted
mainly focused on the potential of application of the old concrete as an aggregate for production of
conventionally vibrated or self – compacting concrete. The presence of old cement mortar significantly
affects a number of physical and mechanical properties, of both recycled aggregate and concrete with
recycled aggregate. Available data from the literature, and own previous researches are used in this paper
to show the influence of recycled concrete aggregate on the characteristics of self – compacting concrete
in the fresh and in the hardened state.

Кey words: Recycled concrete aggregate, self – compacting concrete, sustainable developement

UTICAJ PRIMENE RECIKLIRANOG AGREGATA NA SVOJSTVA

SAMOUGRAĐUJUĆEG BETONA
Rezime: Poslednjih godina problem zaštite životne sredine i zahtevi održivog razvoja postaju sve
striktniji, te je sproveden veliki broj istraživanja širom sveta sa fokusom na potencijalnoj primeni starog
betona kao agregata za spravljanje vibriranog ili samougrađujućeg betona. Prisustvo starog cementnog
maltera značajno utiče na svojstva kako recikliranog agregata, tako i betona sa ovim agregatom.
Dostupni podaci iz literature, kao i sopstvena eksperimentalna istraživanja su korišćeni u ovom radu za
prikazivanje uticaja recikliranog agregata na svojstva samougrađujućeg betona u svežem i očvrslom
stanju.

Ključne reči: reciklirani agregat, samougrađujući beton, održivi razvoj

1
PhD, professor, College of Applied Studies in Civil Engineering and Geodesy, Hajduk Stankova 2, Belgrade,
e-mail: ivickad@gmail.com
2
MA, lecturer, College of Applied Studies in Civil Engineering and Geodesy, Hajduk Stankova 2, Belgrade, e-
mail: prodic_80@yahoo.com

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1. INTRODUCTION
Due to the changes in the requirements and planning of concrete structures,
excessive amount of construction and demolition (C&D) waste is generated in urban
areas worldwide. Annually, 900 million tonnes of C&D waste is estimated in Europe,
USA and Japan [1]. The control and management on C&D waste is becoming a
worldwide challenge, especially for the major urban centres. Considering the
environmental pollution and the consumption of limited natural sources it is crucial to
reuse and recycle C&D waste. The production of recycled concrete aggregate from
C&D waste is important issue since it provides an alternative mean to the dependence
of construction industry on natural aggregates and the critical shortage problem of
natural aggregate sources. It is estimated that in the Republic of Serbia, about 1
million tons of construction and demolition waste is annually produced. This waste
ends up in landfills of municipal waste, and is also used as inert material for coverage
of waste at landfills. Recycling construction waste actually does not exist [2].
Self – compacting concrete (SCC), according to many authors “the most
revolutionary discovery of concrete industry of the 20th century”, does not need
vibrating when placing and compacting. Under the influence of its own weight, it
completely fills all parts of the formwork, even in the presence of dense
reinforcement. With self–compacting concrete, its most important characteristics are
in its fresh state. When designing mixes, emphasis is placed on the ability of concrete
to be levelled out only under the influence of its own weight and to fully fill the
formwork of any shape and dimensions without leaving voids, to pass through dense
reinforcement without blocking, to retain a homogenous structure without separating
aggregate from paste or water from the solid phase, as well as without the tendency of
coarse aggregates to “fall” through the concrete mass under the influence of gravity
(segregation). Therefore, the key characteristics of fresh SCC are floating, viscosity
(expressed by floating rate), passing ability and resistance to segregation [3].
The potential use of recycled aggregates in the SCC composition increases the
ecological value and partly solves the issues of waste disposal sites generated by
construction and demolition of structures. Since this aggregate differs from the
natural aggregate in its sharp-edged shape of grains and the layer of old cement paste
which envelops them, its application will cause certain specificities in the design and
characteristics of fresh self-compacting concrete, which is the subject of this paper.

2. RECYCLED CONCRETE AGGREGATE

Technological process for the production of recycled aggregates involves crushing
pieces of old concrete (Figure 1) to a certain grain size and their sieving, which is
preceded by the separation of metal parts, using magnetic separator, and manual or
mechanical removal of foreign substances. Grains of recycled aggregate, obtained by
this recycling process, consist of grains (or grain parts) of natural aggregates and
cement mortar of original concrete which partially or completely wraps them. The

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amount of cement mortar in recycled aggregates ranges from 25% to 65% (expressed
in volume percentages) and it differs among different fractions – the finer fraction,
the greater the amount of cement mortar. Water absorption of coarse recycled
aggregate ranges from 3.5% to 10%, and of small aggregate from 5.5% to 13% [4].

Figure 1 - Production of recycled aggregate [5]

The presence of old cement mortar, which is of less density and higher porosity
than grains of natural aggregates, significantly affects a number of physical and
mechanical properties, of both recycled aggregate and concrete with recycled
aggregate, i.e. causes “ worse” properties of recycled aggregate compared to natural
aggregate. Therefore, numerous researches have been carried out worldwide with the
aim of improving recycling technologies and obtaining recycled aggregates that
would be practically identical to natural aggregate in their properties or quality. Some
of them are: submerging in HCI (hydrochloric acid) solution at 0.1 molarity for 24 h
at 20 ˚C, submerging in water glass (Na2O·ηSiO2 sodium silicate) for 30 min,
submerging in cement–silica fume slurry for 30 min, the implementation of two-stage
mixing approach [1].

3. EXPERIMENTAL RESEARCH
3.1. Composition of Concrete Mixes
For the purposes of the experimental work, nine three-fraction concrete mixes
have been made. Cement PC 42.5R (Holcim Popovac) has been used as well as
mineral additives: lime (manufacturer “Jelen Do”), fly ash (from the power plant
“Nikola Tesla B” in Obrenovac), and silica fume (product of Sikafume , a
manufacturer of building chemicals SIKA); natural aggregate (Luka “Leget”,
Sremska Mitrovica), recycled aggregate obtained by crushing demolished retaining
wall in the quarry Ostrovica, near Nis. Control concrete was made with each of the
additives and a natural aggregate; in mixes K50, P50 and S50, fraction 8/16mm was
replaced by the recycled aggregate, and in mixes K100, P100 and S100, both coarse
fractions (4/8 and 8/16) were replaced by recycled fractions. In all the mixes,
superplasticizer ViscoCrete 5380 (manufacturer SIKA) has been used, which was

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dosed according to the manufacturer. The criterion in the designing mixes was to
achieve the same consistency of concrete, i.e. slump-flow class SF2, which includes
the usual uses of concrete and involves spreading from 66 to 75cm. While making
concrete mixes, the aggregate was first mixed with half of the required water for a
period of about 30 seconds, and then other components were added. When used
recycled aggregate, the amount of water which was absorbed by the aggregate in 30
minutes (II fraction 2.22%, III fraction 1.5%) was added, although this principle
could not be consistently applied. Composition of concrete mixes is shown in Table
1. The fresh concrete tests were done for density, fluidity - slump flow test according
to EN 12350-8, viscosity – T500 test according to EN 12350-8, the ability of the
passage between the reinforcement – L box test according to EN 12350-10,
segregation resistance – Sieve segregation test according to EN 12350-11 [6].
Table 1 – Concrete mixes
cement lime fly ash sil. fume 0/4mm 4/8mm 8/16mm water VSC5380
(kg/m3) (kg/m3) (kg/m3) (kg/m3) (kg/m3) (kg/m3) (kg/m3) (kg/m3) (kg/m3)
EK 400 120 0 0 770.86 306.28 532 170.8 4.94
EP 400 0 120 0 770.86 306.28 532 192.66 4.94
ES 400 0 0 52 770.86 306.28 532 185.71 4.94
K50 400 120 0 0 809.14 306.28 505.43 182.86 5.08
P50 400 0 120 0 809.14 306.28 505.43 214.28 5.08
S50 400 0 0 52 809.14 306.28 505.43 197.14 5.08
K100 400 120 0 0 809.14 306.28 505.43 189.5 5.08
P100 400 0 120 0 809.14 306.28 505.43 221 5.08
S100 400 0 0 52 809.14 306.28 505.43 208.6 5.08

3.2. Test results

The test results for concrete in the fresh state are shown in Table 2.
Table 2 – Test results for concrete in the fresh state
density Slump-flow T500 L-box Sieve
(kg/m3) cm s H1/H2 segregation,%
EK 2418 73 4 1 12.4
EP 2288 70 4 0.94 11
ES 2416 66 6 0.91 6.8
K50 2362 70 5 0.96 12
P50 2279 70 5 0.95 7.8
S50 2324 67 5 0.94 5.2
K100 2347 69 5 1 10
P100 2298 66 6 0.91 5.5
S100 2359 66 6 0.92 7.5

Testing compressive strength was carried out on the cubes with edges of 15cm.
The test results for compressive strength after 2, 7 and 28 days are shown in Chart 1.

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COMPRESSIVE STRENGTH

80
Strength value (MPa)

70
60
50 2 days
40 7 days

30 28 days

20
10
0
EK EP ES K50 P50 S50 K100 P100 S100

Concrete mix
Chart 1: Compressive strength

4. THE RESULTS ANALYSIS

While designing concrete mixes, in order to obtain the same consistency because
of the use of recycled aggregate, it was necessary to intervene in two directions: to
increase the amount of water and to reduce the amount of III fraction by 5%,
simultaneously increasing the amount of sand by 5%. Without these interventions in
the composition, it was impossible to achieve self-compacting of mixes because of
the sharp-edged grain shape of recycled aggregates and granulometric composition
itself (recycled aggregate had 7% of oversized grains).
Slump –flow test: Fresh concrete was spread from 66 to 73cm which designed
mixes of class SF2 which fits in most common use of concrete in construction. To
achieve the same consistency, when lime was used as a mineral addition, the use of
the recycled aggregate III fraction caused an increase in water-cement ratio from 0.43
to 0.46, while in the case of using I and II recycled fractions, water-cement ratio was
0.47. When fly ash was used as a mineral additive, water-cement ratio increased from
0.48 to 0.55, and when used silica fume, the increase of the water-cement ratio was
from 0.46 to 0.49 and 0.52, due to the use of recycled aggregate. The slightest
movement was recorded in mixes with silica fume, where it is necessary to take into
account their smallest water-cement ratio.
T500 is the time that concrete reaches 500mm, and it is measured when doing
slump-flow test. It represents a check of viscosity of the mix; the recommended
interval for class SF2 is from 3.5 to 6.0s, and all mixes “fit” into it. Since the use of
recycled aggregate caused reduction of spreading concrete, all mixes with recycled

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aggregates had longer period of time T500, compared to the control concrete mix,
regardless of the type of used mineral additive.
L – box test: due to the application of recycled aggregates, horizontality of the
concrete decreases, whereby the combination of lime and recycled aggregate gave the
best results.Blocking of aggregate grains between reinforcement rods was not
recorded in any case.
Segregation test: reduced spreading of fresh self-compacting concrete, due to the
use of recycled aggregates, means greater resistance to segregation, regardless of the
type of applied mineral additive.
When using III and II and III recycled fractions, density in the fresh state is
reduced by 2.3% and 2.9% (with lime), reduced by 0.4% and increased by 0.4% (with
fly ash), and reduced by 3.8% and 2.4% (with silica fume).
Considering mixes with lime, it can be concluded that the differences in the
obtained compressive strength, when using natural and recycled aggregate, are
relatively small, 4.51 MPa (6.8%) and 6.38 MPa (9.6%) – comparison of control
concrete with mixes in which one or both coarse fractions are replaced. In mixes with
fly ash, the difference is 12.3 MPa (19.2%) and 16.8 MPa (26.2%). Greater difference
in strength among mixes with fly ash can be explained by the uneven quality of
recycled aggregate, which represents a major problem of their application. In the
group of mixes with silica fume, the difference between the control concrete mix and
other two mixes was 2.61 MPa (3.6%) and 7.81 MPa (10.8%). The fastest increment
of strength was found in mixes with silica fume. In all concrete mixes with natural
aggregate, a failure was recorded through cement paste, while in mixes with recycled
aggregate, the failure was found through aggregate, no matter which mineral additive
was used.

5. CONCLUSIONS
Use of recycled aggregates solves the problems of over-exploitation of natural
aggregates and of disposing of concrete waste. Increased porosity, caused by the
presence of the old cement paste, and sharp-edged grain shape of recycled aggregates,
adversely affect the properties of fresh self-compacting concrete, so it is necessary to
increase water-cement ratio and/or intervene in the amount of I fraction. An
additional quantity of water is determined by measuring the water absorption of the
recycled aggregate.
Reduction of compressive strength depends on the quality of the applied recycled
aggregate and it is possible to achieve a reduction of only a few percent compared to
the concrete mixes with natural aggregates. The more qualitative the original concrete
was, the better characteristics the newly made concrete will have. It is preferable that
the aggregate is made of concrete of the same brand so that its quality will be as
uniform as possible. In order to remove cement stone from an aggregate grain, a
number of advanced recycling technologies have been developed.

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ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry for Science and Technology, Republic of Serbia. This support is
gratefully acknowledged.

REFERENCES
[1] Guneyisi E, Gesoglu M, Algın Z, Yazıcı H: Effect of surface treatment methods
on the properties of self-compacting concrete with recycled aggregates,
Construction and Building Materials, 64 (2014), p.172–183
[2] Trumić M, Trumić M. (2011): Uloga pripreme u reciklaži otpada i održivom
razvoju Srbije: Stanje i perspektive pripreme mineralnih sirovina u Srbiji,
Inženjerska Akademija Srbije, Beograd, str. 73-93
[3] EFNARC, ERMCO, EFCA, CEMBUREAU, bibm: The European Guidelines for
SCC:Specification, Production and Use; May 2005, p68.
[4] Radonjanin V., Malešev M., Marinković S.: Mogućnosti primene starog betona
kao nove vrste agregata u savremenom građevinarstvu, ZAŠTITA
MATERIJALA, 51 (2010) broj 3, str. 178 – 188
[5] www.concreterecycling.org
[6] Despotović I.: Uticaj različitih mineralnih dodataka na osobine samougrađujućeg
betona, doktorska disertacija, Građevinsko- arhitektonski fakultet, Niš 2015.

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UDK: 691
1
Dušan GRDIĆ
Nenad RISTIĆ2
Gordana TOPLIĈIĆ-ĆURĈIĆ3

EFFECTS OF ADDITION OF FINELY MILLED CATHODE TUBE

GLASS POWDER ON CONCRETE PROPERTIES
Abstract: The paper presents the results of testing of physical and mechanical properties of concrete
which was made with addition of 0 to 10 %, at 2.5% increments, of finely milled recycled glass obtained
from cathode tubes. The glass was milled to the fineness allowing it to completely pass through the sieve
opening of 0,063 mm. Apart from the usual tests of the properties of fresh concrete, the hardened
concrete underwent the bending tensile strength, splitting tensile strength and pull off strength tests at the
age of 28 days. Based on the statistical processing of the obtained result, the effects of the addition of
finely milled glass on the concrete properties were determined.

Кey words: concrete, recycled glass, compressive strength, tensile strength, pull off

UTICAJ DODATKA RECIKLIRANOG STAKLA OD KATODNIH

CEVI VELIKE FINOĆE MLIVA NA SVOJSTVA BETONA
Rezime: U radu su prikazani rezultati ispitivanja fiziĉkih i mehaniĉkih svojstava betona koji je spravljen
sa dodatkom 0 do 10%, sa korakom od 2,5%, fino samlevenog recikliranog stakla koje potiĉe od
katodnih cevi. Staklo je samleveno do finoće mliva koja omogućava da bez ostatka može da proĊe kroz
sito otvora 0,063 mm. Pored uobiĉajenih osobina svežeg betona, na oĉvrslom betonu utvĊene su
vrednosti ĉvrstoće pri pritisku pri starosti od 2, 7, 28 i 90 dana. TakoĊe, utvrĊene su vrednosti ĉvrstoće
pri zatezanju savijanjem, ĉvrstoće pri zatezanju cepanjem i pull off ĉvrstoća pri starosti od 28 dana. Na
osnovu statistiĉke obrade dobijenih rezultata utvrĊen je uticaj dodatka fino samlevenog stakla na svojstva
betona.

Ključne reči: beton, reciklirano staklo, ĉvrstoća pri pritisku, ĉvrstoća pri zatezanju, pull off

1
Asistent, GAF Univerzitet u Nišu, ul. Aleksandra Medvedeva 14, Niš, Srbija, dusan.grdic@gaf.ni.ac.rs
2
Dr asistent, GAF Univerzitet u Nišu, nenad.ristic@gaf.ni.ac.rs
3
Vanredni prof., GAF Univerzitet u Nišu, gordana.toplicic.curcic@gaf.ni.ac.rs

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1. INTRODUCTION
Ferdinand Braun was a scientist who designed the first cathode-ray tube in 1897.
Until 1920, cathode-ray tubes (CRT) were used for reception and emission image of
the first TV sets [1]. By the mid 20th century the first CRTs displaying image in color
were introduced. One of the basic raw materials used for fabrication of CRT glass is
silica (silicon dioxide), whose share is 50-60% [2]. In addition, the tubes are coated
by metal oxides of barium and iron which serve as a protection from dangerous
radiation when using the electronic devices. The European catalogue of waste
materials of 2002 classified the waste glass made from recycled CRTs as dangerous
was which must undergo certain treatment prior to being disposed at the landfills in
order to remove all the matter potentially dangerous for humans and nature (lead,
barium and strontium) [3].
Production of CRT glass increases every year. The mentioned catalogue of waste
estimated in 2002 that he production of CRT glass reached 83.300.000 of units. Given
the such extensive production it is logical that after a certain time, due to the
development of electronics and obsolescence of many devices, proportionally huge
waste will be generated. Data coming from many countries indicate the increase of
the waste glass at the annual level. In California only, one of the most developed
states of the USA, every year three million TV sets and almost as many computer
monitors are disposed to landfills. Certain projections indicate that till 20150, the
annual production of CRT glass in the world will be increased for almost six times
[4]. Therefore, it can be concluded that waste CRT glass is a huge environmental
problem for the entire world, and that it must be seriously addressed. One of the
possible solutions is using the recycled glass to produce concrete.
Emam Ali and Sherif Tersawy tested the properties of fresh and hardened SCC,
where they partially replaced the fine aggregate grade with recycled glass. The fine
aggregate replacement share ranged between 0% and 50% by mass, with 10%
increments. The testing results showed that the slump flow increased with the
increase of replacement glass share in concrete. On the other hand, a certain decrease
of compressive strengths and tensile splitting strength were recorded, as the share of
replacement glass was increased [5].
Kou and Poon, researchers from the Faculty of Civil Engineering of Hong Kong,
in addition to the previously mentioned experiments of SCC with added glass, also
tested concrete shrinkage and resistance to chloride penetration. The results showed
that with the increase of share of the added glass, shrinkage decreases, while the
resistance of concretes to chloride penetration increases [6]. However, one of the
most important conclusions in the papers [5] and [6], is that it is possible to
successfully make a SCC with addition of recycled glass.
One of the potential usages of recycled CRT glass is replacement of a part of
cement constituting mortars and concretes. In order to justify usage of glass as a
partial replacement for cement, it is necessary to previously prove the puzzolanic
activity of the glass.

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The main problem when using recycled glass as concrete aggregate is potential
for the rise of alkali-silica reaction (ASR). Recycled glass has a high content of
amorphous silicon (e.g. glass bottles around 70%) which has a potential of reacting
with the alkali in cement and ASR gel can be generated in the process [7]. ASR gel
in humid conditions would expand in time, which would lead to the onset of cracks
and later to the total destruction of hardened concrete. The size of the glass grains
has a significant impact on the AS reactivity of glass. [7-10]. Some of the latest
researches indicate that the size of the cracks inside the glass grains, which are
grained in the grounding process, determine AS reactivity [7,8]. In cases of large
internal cracks, it is easier for ASR to set in. On the other hand, a very finely ground
glass powder does not cause ASR since less micro-cracks are present in it [8].

2. MATERIALS USED IN THE EXPERIMENT

Pure Portland cement CEM I 52,5R was used for making concrete mixes, as it
meets all the quality requirements of the standard SRPS EN 197-1. Also, three
fractions of the South Morava river aggregate were used, whereby 0-4 mm fraction
had a share of 45%, 4-8 mm fraction had a share of 25%, while the third 8-16 mm
fraction had a share of 30% in the mixture.
Experimental glass was provided to the Laboratory of building materials by the
company “Jugo - Impex” E.E.R. d.o.o. It is a CRT glass which the company
processes in the procedure of recycling of old TV sets and other electronic devices.
Large shards of glass (figure 1, left) were ground to the fineness of 0-4mm in the
asphalt plant of the company “Vodogradnja” Pukovac. The glass was milled to the
desired fineness of 0,063 mm in the Laboratory of building materials (figure 1,
right).

Figure 1 – Glass shards after recycling (left) and milled glass, finer than 0,063 mm (right)

The oxide composition of clear glass is common, and corresponds to the ratio
N2O : CaO : SiO2 = 1 : 1 : 6, as confirmed by a chemical analysis (SiO2 – 72,61%,
Na2O – 13,12%). The share of other oxides (Al2O3, MgO, K2O, SO3) is minor. No
chemical admixtures were used in the experiment.

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3. EXPERIMENTAL RESEARCH RESULTS

3.1. Glass puzzolanic activity tests
Puzzolanic activity of the glass was tested according to the standard SRPS
B.C1.018:2001. The used standard classifies the puzzolanic material in three ways:
 According to the content of reactive silica (SiO2)
 According to the particle size distribution
 According to the mechanical properties
Glass puzzolanic activity was examined on the basis of the tested mechanical
properties of mortar. The glass must have grains finer than 0,063 mm and be dried at
the temperature of 98C. For preparation of mortar were used, 1350 g standard sand
composed of three fractions, 300 g of fine CRT glass, 150 g of standard hydrated lime
and 270 cm3 of water. Mechanical strengths are tested on the test specimens having
dimensions 40 mm x 40 mm x 160 mm. The test specimens are hermetically enclosed
in tin boxes, where after the first 24h spent in laboratory conditions they continue to
be cured at the temperature of 55C for additional six days. The results of the
obtained mechanical properties of mortar are presented in table 1.

Table 1 – Results of mechanical properties of mortar

Test Flexural strength [N/mm2] Compressive strength [N/mm2]
specimen:
5,76
1 2,36
5,82
5,76
2 2,28
5,82
5,95
3 2,43
5,82

The material is considered to be puzzolanically active and it is ranked to have no

less than class 5, if at the age of seven days the minimum flexural strength is 2 MPa
and compressive strength 5 MPa, which was proved with this test. The proved
puzzolanic activity is in agreement with the research [7,8,10].
3.2. Concrete mixes composition
A total of five concrete mixes was made in the experiment (table 2). The goal was
to make a classic concrete, without any chemical admixtures such as
superplasticizers and air-entraining agents. The reference concrete was made with
400 kg of cement and 1720 kg of aggregate having three fractions. Water/cement
ratio was kept constant at 0,50. The remaining four concrete batches were made by
replacing a portion of cement with CRT glass. A protion of the cement mass was
replaced with the recycled glass, the mass portions being 2,5% (the concrete marked
C2,5), 5% (C5,0), 7,5% (C7,5) and 10% (C10,0).

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Table 2 – Composition of the concrete mixes used in the experiment

Aggregate Glass Cement Water
Concrete 0/4 mm 4/8 mm 8/16 mm <0,063mm
% kg/m3 % kg/m3 % kg/m3 kg/m3 kg/m3 kg/m3
E 45 774 25 430 30 516 0 400 200
C2,5 45 774 25 430 30 516 10 390 200
C5,0 45 774 25 430 30 516 20 380 200
C7,5 45 774 25 430 30 516 30 370 200
C10,0 45 774 25 430 30 516 40 360 200

3.3. Test results and result discussion

The results of fresh concrete tests are presented in table 3. Slump test was
conducted according to the standard SRPS ISO 4109:1997, and the content of
entrained air was tested according to the standard SRPS ISO 4848:1997.

Table 3 – Fresh concrete test results

Density Entrained air
Concrete Slump class
[kg/m3] content [%]
E 2351 S2 (80 mm) 2,3
C2,5 2348 S2 (85 mm) 2,2
C5,0 2367 S2 (70 mm) 2,4
C7,5 2345 S2 (80 mm) 2,5
C10,0 2332 S3 (100 mm) 2,5

With the increase of glass content, there was no notable variation of density which
averaged at 2350 kg/m3. Slump class was S2, except in the case where 10% of glass
was added and where slump was slightly higher – S3. A similar conclusion can be
drawn about the content of entrained air since the results were fairly uniform, too.

Tabela 4 – Compressive strength values at the ages of 2,7, 28 and 90 days

Age [days]
Concrete 2 7 28 90
fp [N/mm2] fp [N/mm2] fp [N/mm2] fp [N/mm2]
E 29,1 36,4 44,2 50,9
C2,5 28,0 35,6 41,2 48,5
C5,0 27,1 34,6 40,0 47,1
C7,5 27,4 34,1 38,7 45,2
C10,0 26,1 32,6 38,2 40,7

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The following parameters were tested on the hardened concrete: compressive

strength (SRPS ISO 4012:2000), tensile splitting strength (SRPS ISO 4108:2000),
flexural strength (SRPS ISO 4013:2000) and Pull off strength (SRPS EN 1542). The
values of compressive strength at the age of 2,7, 28 and 90 days were presented in
table 4.
The values of compressive strengths of all concrete mixes increase in the course of
time, which was expected. It can be concluded that with the uniform increase of
added glass content there is a uniform decrease of compressive strengths in
comparison with the reference concrete, figure 2. Yet, there is no notable difference
in compressive strengths of the reference concrete and C2,5, C5,0 concretes, nor even
of C7,5 concrete. At the age of 28 days, the decrease of compressive strengths ranged
from 6,79% for C2,5 concrete up to 12,44% for C7,5 concrete. At the age of 90 the
decrease of strength in comparison with the reference concrete ranges between 10%
for C2,5 concrete up to 16,14% for C7,5 concrete batch. The most prominent decrease
of compressive strengths was measured in the case of concrete with 10% of recycled
glass added. At the age of 28 days, this decrease in strengths was 13,57%, while at the
age of 90 days the strength of C10 concrete batch was as much as 20,04% lower than
the reference concrete.

Figure 2 – Variation of compressive strength at the ages of 2, 7, 28 and 90 days in the

function of quantity of added glass

The results of tensile splitting strength and tensile flexural strength were presented
in figure 3. Through the statistic processing of data, it was concluded that the
decrease of tensile strength is a polynomial function of the second degree with a high
degree of correlation.

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The highest decrease of tensile splitting strength of 28% was measured at C10
concrete. The decrease of flexural strength is lower in comparison to splitting strength
so in the case of the highest content of added glass it amounts to only 12,5%.
Average values of bonding strength are presented in figure 4. The results were, to
a great extent uniform, so in this occasion it cannot be assessed how replacement of
one portion of cement with the recycled glass affects the bonding strength.

Figure 3 – Impact of addition of glass on the variation of tensile splitting and tensile flexural strengths

Figure 4 – Impact of addition of glass on the variation of bonding strength

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4. CONCLUSION
Based on the obtained experimental results, the following conclusions can be
made:
 Recycled glass is puzzolanically active, and on the basis of the tested
mechanical properties it can be concluded that it belongs to class 5.
 Replacement of a portion of cement with the recycled glass in the 0 to 10%
range does not have a notable impact on the change of density.
 There is no change in consistency, up to 7,5% of added glass. in case of C10
concrete batch the consistency is changed, in terms of increased slump.
 Increase of added glass content produces a negligible difference of entrained
air content.
 With the increase of the recycled glass content, there is a decrease of
compressive strength. The highest decrease is recorded for the C10 concrete
batch an it is 13,57% at the age of 28 days, i.e. 20,04% at the age of 90 days.
 Tensile splitting strength and tensile flexural strength decrease as the share of
glass in concrete increases. The decrease of tensile flexural strength is
considerable lower than the decrease of tensile splitting strength. For the C10
concrete the decrease of tensile splitting strength is 28%, i.e. only 12,5% for
the tensile flexural strength.
 The results of bonding strength are uniform for all the concrete batches.
Additional tests are necessary to make a definitive decision about the impact
of addition of CRT glass on this type of strength.

ACKNOWLEDGEMENT
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry of Education, Science and Technological Development, Republic of
Serbia. This support is gratefully acknowledged.

REFERENCES
[1] Leigh, Jason, Johnson Andrew, Renambot Luc (2009): Chapter 2 Advances in
Computer Displays, Advances in Computers, volume 77, str. 57-77
[2] Ching – Hwa Lee, Chang – Tang Chang, Kuo – Shuh Fan, Tien – Chin Chang
(2004): An overview of recycling and treatment of scrap computers, Journal of
Hazardous Materials, volume 114, str. 93-100
[3] Zhao Hui, Wei Sun (2011): Study of properties of mortar containing cathode ray
tubes (CRT) glass as replacement for river sand fine aggregate, Construction and
Building Materials, volume 25, str. 4059-4064

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[4] Zhao Hui, Chi Sun Poon, Tung Chai Ling (2013): Utilizing recycled ray tube
funnel glass sand as river sand replacement in the high – density concrete,
Journal of Cleaner Production, volume 51, str. 184-190
[5] Esraa Emam Ali, Sherif H. Al – Tersawy (2012): Recycled glass as a partial
replacement for fine aggregate in self compacting concrete, Construction and
Building Materials, volume 35, str. 785-791
[6] Shi – Cong Kou, Chi Sun Poon (2008): Properties of self – compacting concrete
prepared with recycled glass aggregate, Cement and Concrete Composites,
volume 31, str. 107-113
[7] Farshad Rajabipour, Hamed Maraghechi, Gregor Fisher (2010): Investigating the
Alkali – Silica Reaction of Recycled Glass Aggregates in Concrete Materials,
Journal of Materials in Civil Engineering, volume 22, str. 1201-1208
[8] Hamed Maraghechi, Masha Maraghechi, Farshad Rajabipour, Carlo Pantano
(2014): Pozzolanic reacitivity of recycled glass powder at elevated temperatures:
Reaction stoichiometry, reaction products and effect of alkali activation, Cement
and Concrete Composites, volume 53, str. 105-114
[9] Ahmed Shayan, Aimin Xu (2006): Performance of glass powder as a pozzolanic
material in concrete: A field trial on concrete slabs, Cement and Concrete
Research, volume 36, str 457-468
[10] Rachida Idir, Martin Cyr, Arezki Tagnit – Hamou (2011): Pozzolanic properties
of fine and coarse color – mixed glass cullet, Cement and Concrete Composites,
volume 33, str. 19-29

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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Damir ZENUNOVIĆ
Nesib REŠIDBEGOVIĆ2
Snežana MIĈEVIĆ3
Radomir FOLIĆ4
Eldin HALILĈEVIĆ5

COMPARATIVE ANALYSIS OF CHLORIDE DIFFUSION THROUGH

CONCRETE COVER OBTAINED BY BDT AND PPT
Abstract: Determination of the chloride diffusion through the concrete cover is one of the most
important parameters for modelling the service life of concrete structures. Samples from two different
concrete mixes were made in order to analyze the diffusion of chloride. The experimental research was
performed and profiles of chloride penetration for specific concrete mix were determined. The
comparative analysis of the chloride diffusion process through the concrete cover submerged in salty
water (Bulk Diffusion Test - BDT) and concrete submerged in salty water under various pressures
(Pressure Penetration Test - PPT) were performed. At the end of the paper diffusion coefficients of
chloride relation obtained by BDT and PPT were recommended.

Кey words: chloride diffusion, concrete cover, specimens, experiment

UPOREDNA ANALIZA DIFUZIJE HLORIDA KROZ ZAŠTITNI SLOJ

BETONA UTVRĐENE BDT I PPT TESTOM
Rezime: Definisanje procesa difuzije hlorida kroz zaštitni sloj betona predstavlja jedan od najvažnijih
parametara za modeliranje eksploatacionog vijeka betonskih konstrukcija. U cilju analize procesa
difuzije hlorida uraĊeni su uzorci betona sa dvije razliĉite recepture. Provedena su eksperimentalna
istraživanja i utvrĊen profil prodora hlorida za pojedine recepture. UraĊena je uporedna analiza procesa
difuzije hlorida kroz zaštitni sloj betona potopljenog u zasoljenu vodu (Bulk Diffusion Test - BDT) i
betona potopljenog u zasoljenu vodu pod razliĉitim pritiscima (Pressure Penetration Test - PPT). Na
kraju rada su preporuĉeni odnosi koeficijenata difuzije hlorida kod BDT-a i PPT-a.

Ključne reči: difuzija hlorida, zaštitni sloj betona, uzorci, eksperiment

1
Professor, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla, damir.zenunovic@untz.ba
2
Assistant, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla
3
Professor, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla
4
Prof. Emeritus, Faculty of Technical Sciences, Trg Dositeja Obradovica 6, Novi Sad, r.folic@gmail.com
5
Assistant, Faculty of Mining, Geology and Civil Engineering, Univerzitetska 2, Tuzla

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1. INTRODUCTION
Today, concrete is the most widely used material in civil engineering. This is
because of its availability in the market and competitive price compared to other
materials. The concept of safety of concrete structures has been defined and
elaborated in standards [1]. The challenge for researchers and engineers in
engineering practice is how to ensure a rational durability of concrete structures. This
issue is treated by the literature that deals with modelling the service life of concrete
structures, which is a result of intensive research over the last thirty years. Thus, there
are some important references from this period [2] - [8].
It is well known that reinforcement corrosion is the main cause of reduction of
service life of concrete structures. The two main causes of reinforcement corrosion
are carbonation and contamination of concrete by chlorides. Since this paper is
dedicated to the effects of chlorides, what follows below is the analysis of the effects
of the presence of chloride in concrete. The chloride ions accelerate the chemical
process that leads to corrosion of reinforcement. Chloride ions can occur during the
concrete mixture production, but usually in very small amounts which are insufficient
for a significant development of chemical process that leads to the commencement of
corrosion. The examples of significant amounts of chloride in engineering practice
include buildings near the sea, maintenance of roads and bridges in winter, and
buildings in industrial zones. The chemical process of corrosion is described in a
large number of references. Here, we can mention the book [9] which explains the
process of corrosion and describes the methods of monitoring and preventing the
corrosion process.
In modelling the service life of concrete structures, the effect of presence of
chlorides is defined by specifying the chloride profile. The report [10] gives an
overview of methods for determining the resistance of concrete against chloride
penetration. The key parameters for forecasting the structure's service life are derived
based on the established chloride profile. One of the key parameters is the chloride
diffusion coefficient. The chloride diffusion coefficient depends on humidity and
temperature of the environment, regime of fostering the concrete, time of exposure of
concrete to aggressive action, type of cement, and water-cement ratio. The impact of
individual factors is described in detail in the dissertation [11].
This paper presents a part of experimental research from the research project
called "Modelling the service life of concrete structures in industrial zones",
conducted at the Faculty of Mining, Geology and Civil Engineering at the University
of Tuzla. Chloride diffusion coefficients through the concrete surface layer exposed
to salted water with and without pressure were analyzed. Two concrete mix formulas
were used. The samples were tested by immersing them into salty water (Bulk
Diffusion Test - BDT) and pressuring them with salted water (Pressure Penetration
Test - PPT). The BDT and PPT test procedures are explained in details in [10]. The
paper concludes with recommendations for ratios of chloride diffusion coefficients
through the surface layer of concrete, as determined based on BDT and PPT.

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2. PART OF THE EXPERIMENTAL RESEARCH REFERRING TO

RESISTANCE OF THE SURFACE LAYER OF CONCRETE AGAINST
CHLORIDE PENETRATION
With the objective of conducting a comparative analysis of chloride penetrability
into the surface layer of concrete exposed to salty water without pressure or under
pressure, concrete samples were tested based on two randomly chosen concrete mix
formulas. The formulas were coded as CM (Concrete Mix). Table 1 provides the
basic information about the formulas, while Figure 1 shows the measured rate of
settlement and the appearance of CM1 samples.

Table 1: Formulas of the tested samples

CM1 CM2
Cement: Cement:
CEM II/B-M(S-V)42.5N –320kg CEM II/B-M(S-V)42.5N –440kg
Aggregate: Aggregate:
0-4mm – 840kg 0-4mm – 850kg
4-8mm – 300kg 4-8mm – 284kg
8-16 – 340kg 8-16 – 416kg
16-32 – 500kg 16-32 – 378kg
Water: 160 l Water: 220 l
Water-cement ratio: Water-cement ratio:
w/c = 0.50 w/c = 0.50
Consistency: Consistency:
Rate of settlement 8.0cm. Rate of settlement 9.5cm.

Figure 1: Formula CM1: a) rate of settlement, b) concrete samples

The samples were kept in laboratory conditions 28 days, and then exposed to the
test regime. Part of the samples is immersed into salty water (BDT test) (Fig.2), and
the other part of the sample is exposed to internal pressure in the vessel, which was
compiled specifically for the testing (test PPT) (Fig.3). In both test (BDT and PPT)
pure industrial salt concentration in the water was 16.5%

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Figure 2: CM1 samples – BDT test

Figure 3: Formula CM1: a) test chamber, b) concrete samples in the chamber

According to the test program, the BDT test should last 90 days, while the PPT
test 10 days.
Table 2 presents the sampling regime.

Table 2: Sampling regime

BDT test PPT test
I. 30 days after the I. 2 days under pressure of 2
immersion - 3 samples bars – 3 samples
II. 45 days after the II. 4 days under pressure of 2
immersion - 3 samples bars – 3 samples
III. 60 days after the III. 6 days under pressure of 2
immersion - 3 samples bars – 3 samples
IV. 75 days after the IV. 8 days under pressure of 2
immersion - 3 samples bars – 3 samples
V. 90 days after the V. 10 days under pressure of
immersion - 3 samples 2 bars – 3 samples

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Since the experiment is still under way in time of writing this paper, the BDT test
data were processed for the first 60 days of immersion, while those of the PPT test
were fully processed.
After removing the samples from salty water, the surface layer of concrete was
sampled on the saturated, dry-surface sample. At the same time, two types of
sampling were conducted:
 Sampling by grinding for the purpose of determining the concentration of
chloride along the depth (Figure 4a)
 Sampling by tearing for the purpose of determining the depth of chloride
penetration (Figure 4b)

Figure 4: Formula CM2; a) sample grinding by layers, b) sample tearing

The chloride concentration was determined by the Mohr’s argentometry method,

that is titration using solution of standard silver nitrate (AgNO3) with potassium
chromate (K2CrO4) as an indicator, while the depth of chloride penetration was
determined using the colorimetric approach by spraying the tear-up samples with
silver nitrate of 0.1 M concentration.
The white colour of the surface layer of concrete saturated with chlorides and the
clear line of chloride penetration can be seen in Figure 4b.

3. PRELIMINARY FINDINGS AND COMPARATIVE ANALYSIS

Based on the above sampling, chloride penetration profiles were constructed, from
which the chloride diffusion coefficients were determined as basic parameters for the
development of a model of the concrete's service life which were intended to further
research activities. Figure 5 shows the profiles of chloride penetration into CM1
concrete surface layer in BDT test after 45 days and PPT test after 4 days under the
pressure of 2 bars. Table 3 provides an overview of identified average diffusion
coefficients in the first two ground layers (1-3 and 3-5mm) for individual formulas by
individual BDT and PPT test phases.

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Figure 5: Comparative profiles of chloride penetration in CM1 concrete samples immersed

for 60 days in 16.5% salted water - BDT test, and samples immersed in 16.5% salted water
exposed to pressure of 2 bars for 2 days - PPT test

Table 3: Average chloride diffusion coefficient (m2/s)

CM1 CM2
BDT 30 days: BDT 30 days:
I layer – 3.168 x 10-12 I layer – 1.891 x 10-12
II layer – 5.388 x 10-12 II layer – 6.119 x 10-12
BDT 45 days: BDT 45 days:
I layer – 4.127 x 10-12 I layer – 3.242 x 10-12
II layer – 8.300 x 10-12 II layer – 2.940 x 10-12
BDT 60 days:
I layer – 2.096 x 10-12
II layer – 4.429 x 10-12
PPT 4 days: PPT 4 days:
I layer – 1.290 x 10-11 I layer – 1.474 x 10-11
II layer – 1.161 x 10-11 II layer – 1.523 x 10-11
PPT 6 days: PPT 6 days:
I layer – 1.870 x 10-11 I layer – 8.760 x 10-12
II layer – 1.578 x 10-11 II layer – 1.146 x 10-11
PPT 8 days: PPT 8 days:
I layer – 1.423 x 10-11 I layer – 7.982 x 10-12
II layer – 1.185 x 10-11 II layer – 1.845 x 10-11
PPT 10 days: PPT 10 days:
I layer – 1.123 x 10-11 I layer – 5.606 x 10-12
II layer – 9.470 x 10-12 II layer – 6.403 x 10-12

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Average chloride diffusion coefficients were calculated according the

methodology presented in detail in [10] and [12].
Based on the results processed to the day of writing this paper, a preliminary
comparison of penetration of chloride ions through the concrete surface without
pressure and under pressure has been conducted.
By comparing the values of chloride diffusion coefficients from the BDT test after
45 days it can be seen that diffusion coefficients of the CM2 formula are lower than
those of the CM1. Also, values of diffusion coefficients determined by the PPT test
are lower than those of the CM2 formula.
Based on the comparative analysis of chloride diffusion coefficients obtained
using BDT test after 45 days and PPT it has been concluded that the values vary
depending on duration of the PPT test: 2.77-1.67 for the CM1, and 4.85 - 1.94 for the
CM2 formula.

4. CONCLUSIONS

Based on the presented research results and preliminary analysis it can be

concluded that the chloride diffusion coefficients are higher in concrete exposed to
salty water under pressure than in the freely immersed concrete. Ratios between
chloride diffusion coefficients determined based on PPT test under pressure of 2 bars
and BDT test are within the range of 1.67 to 4.85. The values vary depending on
duration of the PPT test, with the highest values obtained in PPT test in duration of 2
days, with a downward trend as the test duration increases. Differences in ratios of
chloride diffusion coefficients between the CM1 and CM2 formula result from the
fact that the CM2 formula contains larger quantity of cement (see Table 1). Studies
have shown that in concrete with a greater amount of cement there is a more
pronounced level of increase of chloride diffusion coefficient as determined based on
PPT test than determined based on BDT test. The reliability of identified ratios will
be verified in further research.
Based on the above, the PPT test can be clearly more effective for the time-rational
determination of chloride penetration profile and chloride diffusion coefficient in
concrete exposed to aggressive environments than the lengthy BDT test. PPT test can
also serve as an efficient method for assessing the durability of concrete in aggressive
environment under pressure.

ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the
research project TR 36017 supported by the Ministry for Education and
Science Republic of Serbia. This support is gratefully acknowledged (R.
Folić).

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REFERENCES
[1] EN 1990-Eurocode- Basis of structural design, CEN, Brussels, 2002.
[2] CEB: Durable of Concrete Structures, Design Guide, T. Thelford, London, 1992.
p. 112.
[3] Durability Design of Concrete Structures- RILEM Report 14:(Ed. A. Sarja and
E. Vesikari), Spon, London,1996. p.155.
[4] FIB (CEB-FIP), Bulletin 3 – Structural Concrete – Textbook on behaviour,
Design and Performance (Updated knowledge of the CEB/FIP Model Code
1990), Vol. 3, December 1999.
[5] ACI Committee 365. 1R-42: Service-Life Prediction-State of the Art report,
2000. pp. 44.
[6] FIB (CEB-FIP), Bulletin 34 – Model Code for Service Life Design, fib,
Lausanne, Switzerland, 2006, p. 116
[7] FIB (CEB-FIP): Concrete structure management: Guide to ownership and good
practice, TG 5.3, February 2008.
[8] ACI 201.12R-08: Guide to durable concrete, ACI, 2008.
[9] Bohni H. (Ed.): Corrosion in reinforced concrete structures, Woodhead
Publishing Limited, Abington Hall, Abington Cambridge CB1 6AH, England,
2005.
[10] Stanish K.D., Hooton R.D., Thomas M.D.A.: Testing the Chloride Penetration
Resistance of Concrete: A Literature Review, Research project, FHWA Contract
DTFH61-97-R-00022 “Prediction of Chloride Penetration in Concrete”,
University of Toronto, Toronto, Ontario, Canada, 1997.
[11] Bioubakhsh, S.: The penetration of chloride in concrete subject to wetting and
drying: measurement and modelling, Doctoral thesis, UCL (University College
London), 2011.
[12] Gergely J., Bledsoe J.E., Tempest B.Q., Szabo I.F.: Concrete diffusion
coefficients and existing chloride exposure in North Carolina, North Carolina
Department of Transportation, Research Project No. HWY-2004-12, 2006.

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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Ksenija JANKOVIĆ
Marko STOJANOVIĆ2
Dragan BOJOVIĆ3
Ljiljana LONĈAR4
Lana ANTIĆ5
THE INFLUENCE OF NANO-SILICA ON MECHANICAL
PROPERTIES OF ULTRA HIGH PERFORMANCE CONCRETE
Abstract: Application of nano-silica in concrete is one of the possibilities to improve concrete properties
and increasing structure durability. The use of ultrafine powders (nanoparticles) for the manufacturing of
cement-based composites, suitably combined with the use of waterreducing admixtures, allows to reach
excellent mechanical performance thanks to the optimization of the cement-based composite
microstructure. Nano-silica has higher pozzolanic reactivity than silica fume and can reduce cement
content in ultra high performance concrete (UHPC). The main objective of this paper is to evaluate the
influence of different content of nano-silica on properties of UHPC. In addition, the cement content can
be reduced, as well as the CO2 emission in cement factory production.

Кey words: nano-silica, UHPC, mechanical properties.

UTICAJ NANOSILIKE NA MEHANIČKA SVOJSTVA BETONA

IZUZETO VISOKIH SVOJSTAVA
Rezime: Primena nanosilike u betonu je jedna od mogućnosti za poboljšanje svojstava betona i
povećanje trajnosti konstrukcija. Primenom finih praškastih materijala (nanoĉestica) za proizvodnju
kompozita na bazi cementa, kombinovanih sa odgovarajućim hemijskim dodacima za redukciju vode
moguće je dostizanje izuzetnih mehaniĉkih svojstava zahvaljući optimizaciji mikrostrukture cementnih
kompozita. Nanosilika ima veću pucolansku aktivnost od silikatne prašine i može smanjiti koliĉinu
cementa u betonima izuzetno visokih svojstava (UHPC). Glavni cilj ovog rada je procena uticaja
razliĉitih koliĉina nanosilike na svojstva UHPC. Osim toga, smanjenjem sadržaja cementa smanjuje se i
koliĉina CO2 koje emituju fabrike cementa u toku njegove proizvodnje.

Ključne reči: nanosilika, UHPC, mehaniĉka svojstva.

1
PhD, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, ksenija.jankovic@institutims.rs
2
PhD student, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, marko.stojanovic@institutims.rs
3
PhD candidate, IMS Institute, Bulevar vojovde Mišića 43, Belgrade, dragan.bojovic@institutims.rs
4
BScCE, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, ljiljana.loncar@institutims.rs
5
MSc, IMS Institute, Bulevar vojovde Mišića 43, Belgrade, lana.antic@institutims.rs

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1. INTRODUCTION
Development of building materials with improving characteristics and its
application on increasing structure durability and sustainability is one of goals in
building industry. Application of nano-silica (nS) in concrete is one of the
possibilities to improve concrete properties.
Pozzolanic reaction kinetics, morphology and structure of the hydrates and its
influences on the properties of cement-based materials with nano-silica were
investigated 3.
The acceleration of cement hydration depended of total surface size of added nS
particles 4.
The large capillary pores were refined by the nano-silica, due to the combined
contribution of the nano-filler effect and the pozzolanic reaction 1.
The addition of nano-silica also resulted in an enhancement in compressive
strength as well as in transport properties of UHPC. The optimum amount of cement
replacement by nS in cement paste to achieve the best performance was 3 wt.%. 2.
The results showed that the compressive and flexural strength of UHPC increased
with the increase of the nano-silica content up to 3% and due to agglomeration of nS
particles, the mechanical properties decreased slightly when the nano-silica content
was more than 3%. The hydration process was accelerated by the addition of nS. The
porosity and the average pore diameter decreased with the increase of the nano-SiO2
content and aging 5.
The main objective of this paper is to evaluate the influence of different content of
nano-silica on properties of UHPC.

2. COMPONENT MATERIALS AND MIX DESIGN

Cement content of ultra high performance concrete is usually more than 850 kg/m3
and its properties significantly influence on mechanical properties of UHPC. In this
study ordinary portland cement CEM I 42.5 R was used. Silica fume (SF) is use as
secondary binder. It will fill the pores in the cement paste and contributes to
the strength of composite by forming the products of pozzolanic reaction with
the free calcium hydroxide, the product of primary hydration. Nano-silica (nS) has
higher pozzolanic reactivity than silica fume and can reduce cement content in ultra
high performance concrete. Average nano-silica particle size was 7 nm. Two different
cement replacements by nano-silica (2% - concrete marked K2 and 5% for concrete
mixture K5) were used to evaluate its influence on properties of referent UHPC
without nS (K0). Quartz powder (Qp) with average particle size of 50 m and quartz
sand (Qs) up to 4 mm were used as aggregate. A modified polycarboxylates based
superplasticizer was used to allow high water reduction. Brass coated steel fibers with
8 mm length and a diameter of 0.15 mm were used.
Composition of concrete mixtures are shown in Table 1.

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Table 1. Composition of concrete mixtures (kg/m3)
K0 K2 K5
C 950 931 902.5
SF 200 200 200
nS 0 19 47.5
Qp 350 350 350
Qs 570 570 570
B 0 0 0
Water 230 230 230
Admixture 53 53 53
Fiber 235 235 235
Density 2588 2588 2588

3. EXPERIMENTAL RESULTS
Nano-silica and concrete were heated up to 1000 °C. The loss in weight was
recorded. TGA results are shown in Figures 1. All types of concrete had similar
trends. For example, curves for concrete with 2% nano-silica are given in Fig.1.
Weight loss between 500 and 700 °C was the result of Portlandite decomposition, and
up to 900 °C of calcium carbonate decomposition.

Figure 1. Concrete with 2% nano-silica, DTA-TGA

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Pore-size distribution was tested by RapidAir 457 device. With the increase in the
nano-silica content pore-size distribution becoming finer. Results for concrete without
nano-silica and 2% nS cement replacement are given in Figure 2.

log-normal distribution

12.0
Normalized chord length frequency

10.0

8.0

6.0

4.0

2.0

0.0
0.000 0.100 0.200 0.300 0.400 0.500

Chord length (mm)

K0

log-normal distribution

25.0
Normalized chord length frequency

20.0

15.0

10.0

5.0

0.0
0.000 0.100 0.200 0.300 0.400 0.500

Chord length (mm)

K2
Figure 2. Chord length distribution for concrete without and with 2% nS

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Samples for testing the mechanical properties were prepared in molds 4 x 4 x

16 cm by the vibration on vibro-table for 60s. Next day, specimens were demoulded
and put into water and cured up to testing.
The results of flexural strength of concrete with and without the cement
replacement by nano-silica in the function of the age were given in Figure 3.
160

140
Compressive strength (N/mm2)

120

100

80 K0
K2
60
K5
40

20

0
0 5 10 15 20 25 30
Age (days)
Figure 3. Concrete strength in the function of age

Results obtained values of flexural strength of all concrete types are shown in
Table 2.
Table 2. Flexural strength of concrete(N/mm2)
K0 K2 K5
7 days 17.5 16.6 16.0
28 days 19.0 25.0 21.4
In the concrete in which the 2% of cement is replaced with nano-silica, there is a
change in the structure of the cement matrix, so that it has a much greater influence
both on the compressive and flexural strength

4. CONCLUSION
The experimental work presented in this paper is based primarily on the effect of
nano-silica.
Compressive and flexural strength of concrete increases with the addition of nano-
silica for concrete cured 28 days. The same effect was seen at the age of 7 days for
compressive strength, but flexural strength decreased for concrete with nS.

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The mechanical properties decreased when the nano-silica content increased both
for concrete at age of 7 and 28 days.
Cement replacement with nano-silica in the amount of 2% has a better impact on
both the compressive and flexural strength than concrete with 5% nS due to change in
the structure of the cement matrix which is seen in the pore size and distribution.
Based on the results of testing it can be concluded that addition of nano-silica
increases mechanical properties of concrete. Optimal cement replacement with nS
will be subject of further research.

ACKNOWLEDGMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications" supported by
the Ministry of Education, Science and Technology, Republic of Serbia. This support
is gratefully acknowledged.

REFERENCES
[1] Du H, Du S , Liu X, (2014) Durability performances of concrete with nano-
silica, Construction and Building Materials 73: 705–712
[2] Ghafari E, Costa H, Júlio E, Portugal A , Durães L, (2014) The effect of
nanosilica addition on flowability, strength and transport properties of ultra high
performance concrete, Materials and Design 59: 1–9
[3] Hou P, Qian J, Cheng X , Shah S.P, (2015) Effects of the pozzolanic reactivity of
nanoSiO2 on cement-based materials, Cement & Concrete Composites 55: 250–
258
[4] Land G, Stephan D, (2012) The influence of nano-silica on the hydration of
ordinary Portland cement, J Mater Sci 47:1011–1017
[5] Rong Z , Sun W, Xiao H, Jiang G, (2015) Effects of nano-SiO2 particles on the
mechanical and microstructural properties of ultra-high performance
cementitious composites, Cement & Concrete Composites 56: 25–31

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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Ksenija JANKOVIĆ
Dragan BOJOVIĆ2
Marko STOJANOVIĆ3
Ljiljana LONĈAR4
Lana ANTIĆ5
DURABILITY PROPERTIES OF THE SCC CONCRETE WITH MINE
TAILINGS AS A PARTIAL AGGREGATE REPLACEMENT
Abstract: As mine tailings, taken from the landfill and from the production was no significant difference
in chemical composition and pozzolanic activity for further investigation only material from landfill was
use. This paper presents the possibility of using tailings in self-compacting concrete made with ordinary
cement. Concrete specimens in which the aggregate fraction 0/4 mm was replaced with 10 and 20% of
tailings were examined. The resistance on freezing and thawing with and without de-icing salts is used as
an indicator of concrete durability. Also, for two representative types of concrete with different air
content and degree of damage done by destructive test, non-destructive test by device RapidAir 457 was
done.

Кey words: mine tailings, aggregate, self-compacting concrete, durability.

TRAJNOST SCC BETONA SA PRIMENOM JALOVINE KAO

DELIMIČNE ZAMENE AGREGATA
Rezime: Jalovina koja je uzeta sa deponije i direktno iz proizvodnje rude nije imala znaĉajne razlike u
hemijskom sastavu i pucolanskoj aktivnosti, te je za dalja istraživanja korišćen samo materijal sa
deponije. U ovom radu je prikazana mogućnost korišćenja jalovina u samougraĊujućem betonu
spravljenom sa portland cementom. Ispitivani su betonski uzorci u kojem je frakcija agregata 0/4 mm
zamenjena sa 10 i 20% jalovine. Kao pokazatelj trajnosti betona uzete su otpornosti prema zamrzavanju i
odmrzavanju sa i bez soli za odmrzavanje. TakoĊe, za dva reprezentativna tipa betona sa razliĉitim
sadržajem vazduha i stepena oštećenja dobijenih destruktivnim ispitivanjem izvršeno je i ispitivanje bez
razaranja pomoću ureĊaja RapidAir 457.

Ključne reči: jalovina, agregat, samougraĊujući beton, trajnost.

1
PhD, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, ksenija.jankovic@institutims.rs
2
PhD candidate, IMS Institute, Bulevar vojovde Mišića 43, Belgrade, dragan.bojovic@institutims.rs
3
PhD student, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, marko.stojanovic@institutims.rs
4
BScCE, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, ljiljana.loncar@institutims.rs
5
MSc, IMS Institute, Bulevar vojovde Mišića 43, Belgrade, lana.antic@institutims.rs

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1. INTRODUCTION
Large amounts of flotation tailings are generated during the flotation of ore from
the mine. When metal production is increased, the amount of tailings is increased,
which presents a serious environmental problem.
Possibility of using tailings from the copper ore as a partial replacement for natural
river sand in concrete is showen in [4]. The concrete made from mining waste from
copper ore (substitution of up to 60%) had good strength and durability
characteristics.
Onuaguluchi and Eren [2] investigated effect of the application of copper tailings
which substitute 0%, 5% and 10% of cement mass on the properties of fresh and
hardened concrete. Mortars with copper tailings had greater strength and resistance to
abrasion.
Freezing and thawing of hardened concrete is among the most important problems
of the concrete durability.
For concrete exposed to freezing in its exploitation frost class can also be one of
the conditions for determining the class of concrete. This means that the concrete has
to meet a special property - frost resistance, i.e. a specified number of cycles of
alternate freezing and thawing according to SRPS U.M1.016.
Volume of air bubbles and its distribution in the cement paste influence on
concrete resistance on freezing and thawing. According to SRPS U.M1.206 if spacing
factor is less than 0.20 mm complete protection and durability of concrete against
frost is ensured [3].

2. EXPERIMENTAL WORK
In this experimental work, SCC concrete with partial replacement of 10 and 20%
of fine aggregate fractions with tailings were made. Two groups of SCC concrete
were prepared. In both groups, there were three mixtures in which one is standard and
in the other two mixtures a replacement of 10 and 20% of the fine fraction of tailings
was made. Another group of concrete differs from the first in adding the air entraining
agent. The aim is to compare two types of SCC concrete for frost resistance, as well
as resistance of the concrete surface to frost and de-icing salts.
Comparative destructive tests on hardened SCC concrete which was exposed to
frost, the surface of concrete was also exposed to to frost and de-icing salts, as well as
non- destructive testing of pore spacing factor in concrete were conducted using the
Rapid Air 457 device.
2.1. Component Materials
For the tests described in this paper self-compacting concretes with a part of the
aggregate replaced with tailings from the mine were made two types of concrete with
and without air entraining (Table 1).

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For the preparation of self-compacting concrete the following materials were used:
 Cement: CEM I 42.5 R, Lafarge BFC, Beocin
 Aggregate: river, washed and separated into fractions 0/4, 4/8, 8/16 mm
 Mineral additive Type I: filler
 Mine tailing
 Chemical admixture: 1) Superplasticizer VSC 5380 (polycarboxylate), Sika –
Serbia
 Chemical admixture: 2) Air entraining admixture SIKA Aer, Sika – Serbia
 Water: potable water
2.2. Composition of concrete mixtures
Mixture composition is shown in Table 1.
Table 1. Composition of concrete mixtures
Components materials
Mine VSC
Concrete series Cement Aggregate Filler Aer Water w/b
tailing 5380
kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 %
J_SCC-0% 350 1740 100 0 3.6 - 170 0.378
J_SCC-10% 350 1740 100 78.3 3.6 - 170 0.378
J_SCC-20% 350 1740 100 156.6 3.6 - 170 0.378
J_SCC-0%+A 350 1685 100 0 3.6 0.010 165 0.367
J_SCC-10%+A 350 1685 100 75.8 3.6 0.010 165 0.367
J_SCC-20%+A 350 1685 100 151.6 3.6 0.010 165 0.367

Fresh concrete is designed to meet the minimum properties of self-compacting

concrete, according to EN 206-9 standard. A referent mixture and two mixtures in
which a part of the fine aggregate (10 or 20%) was replaced with tailings were
prepared [1].
Bulk density of hardened concrete was tested according to SRPS EN 12390-7
standard and ranged from 2300 to 2400 kg/m3). Air content of fresh concrete was
tested according to SRPS EN 12350-7 standard and ranged from 0.8 to 3.4%.
2.3. Experimental results
The samples, cubes (d=100mm), were made in laboratory conditions, and were
prepared and tested according to SRPS U.M1.016 class F-200.
The criterion for determining the frost resistance was that the compressive
strength of frozen samples must be at least 75% of the strength the samples of
equivalent age that weren’t frosted have.

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Table 2. Destructive testing of SCC concrete to frost
Results of testing resistance of concrete to frost
Concrete series
Etalon I F150 Etalon II F200
J_OPC-0% 67.7 60.7 75.8 59.5
J_OPC-10% 73.1 65.4 80.2 62.4
J_OPC-20% 70.8 62.7 75.4 58.7
J_OPC-0%+A 66.2 62.1 71.3 60.1
J_OPC-10%+A 61.7 58.1 67.5 56.5
J_OPC-20%+A 63.9 61.1 69.7 57.5

Figure 1 – Ratio of compressive strength F/M (%)

Concrete resistance to frost and de-icing salt is determined by the degree of

damage to the concrete surface of the sample after 25 cycles of freezing and thawing.
The samples are exposed to a temperature of -20 0C for 16 to 18 hours and then at a
temperature of 200C for 6 to 8 hours, according to SRPS U.M1.055. Test results were
show in Table 3.
Table 3. Results Degree of damage
Concrete series
Results of testing J_SCC- J_SCC- J_SCC- J_SCC- J_SCC- J_SCC-
0% 10% 20% 0%+A 10%+A 20%+A
Degree of damage 2 2 2 2 1 1

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For the same samples were cut off one side of the cube h=10 mm to determine the
spacing of micropores in concrete with Rapid Air 457. Test results were show in
Table 4 and Figure 2.
Table 4. Test results obtained by device RapidAir 457
Concrete series
Results of testing
Rapid Air 457 J_SCC- J_SCC- J_SCC- J_SCC- J_SCC- J_SCC-
0% 10% 20% 0%+A 10%+A 20%+A
Air content (%) 4.62 4.19 2.81 4.01 3.56 2.93
-1
Specific surface (mm ) 25.31 23.07 35.15 25.84 40.94 48.92
Spacing factor (mm) 0.212 0.244 0.259 0.364 0.148 0.135
-1
Void frequency (mm ) 0.293 0.242 0.275 0.259 0.365 0.358

Figure 2 – Classification of the pores in SCC concrete series J_SCC-20%+A

3. CONCLUSION
The investigation of SCC concrete with partial replacement of fine fractions of 10
and 20% with tailings showed good results for frost resistance. Concrete that is in
itself had air entraining agent showed better test results. All concretes have met the
minimum ratio of F/E compressive strength of 75%.
Concrete surfaces which are exposed to frost and de-icing salts showed that
concrete J_SCC-10%+A and J_SCC-20%+A have low scaling (1st degree of damage)

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graded - resistant. All other concretes have achieved the 2nd level of damage, that is,
the surfaces of these concretes are not resistant to frost and de-icing salts.
Checking concrete under the Rapid Air 457 microscope provided the indicators
that are consistent with the results of the destructive tests. Spacing factor was less
than 0.2 mm for concrete J_SCC-10%+A and J_SCC-20%+A.
For the concrete to be self-compacting, a large amount of fine particles is
necessary. That amount was obtained from adding fillers. Further research is needed
to check the tailings in the SCC concrete as a partial replacement of fine aggregate,
but without the use of fillers.

ACKNOWLEDGMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications" supported by
the Ministry of Education, Science and Technology, Republic of Serbia. This support
is gratefully acknowledged.

REFERENCES
[1] EN 206-9 - Concrete - Part 9: Additional Rules for Self-compacting Concrete
(SCC)
[2] Onuaguluchi O., Eren O. Recycling of copper tailings as an additive in cement
mortars, Construction and Building Materials 37 (2012) 723–727
[3] SRPS U.M1.206 – Concrete — Specification, performance, production and
conformity — Rules for the implementation of SRPS EN 206-1(2013)
[4] Thomas B. S., Damare A., Gupta R.C. Strength and durability characteristics of
copper tailing concrete, Construction and Building Materials 48 (2013) 894–900

[207]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Marija JELĈIĆ RUKAVINA
Ana BARIĈEVIĆ2
Marijana SERDAR3
Martina PEZER4
Dubravka BJEGOVIĆ5

BEHAVIOR OF REINFORCED CONCRETE WITH RECYCLED

TYRE POLYMER FIBERS AFTER FIRE EXPOSURE
Abstract: Negative effects such as spalling caused by fire exposure of concrete structures can be
diminished by incorporation of polypropylene (PP) fibers. Due to various initiatives taken worldwide in
an attempt to convert waste materials into new products, the main objective of this research is to quantify
contribution of recycled tyre polymer (RTP) fibers as replacement for PP fibers. In the scope of
presented research ordinary concrete, concrete with 1kg/m3 of PP fibers and concrete with 5, 10 and 15
kg/m3 of RTP fibers were considered. Analysis encompassed mechanical properties of unheated concrete
and after the exposure to elevated temperatures up to 800°C.

Кey words: high temperatures, fiber reinforced concrete, recycled tyre polymer fibers.

SVOJSTVA MIKROARMIRANOG BETONA S RECIKLIRANIM

VLAKNIMA NAKON DJELOVANJA VISOKIH TEMPERATURA
Rezime: Upotrebom polipropilenskih vlakana u betonskoj mješavini može se smanjiti ili potpuno izbjeći
pojava eksplozivnog odlamanja, kojeg na betonske elemente uzrokuje djelovanje visokih temperature.
Zbog razliĉitih inicijativa širom svijeta da se otpadni materijali upotrijebe za proizvodnju novih
proizvoda, glavni cilj ovog istraživanja je kvantificirati doprinos recikliranih polimernih vlakana iz
otpadnih guma kao zamjena za polipropilenska vlakna u betonu. U ovom radu su ispitana mehaniĉka
svojstva prije i nakon izlaganja visokim temperaturama do 800°C uzoraka od obiĉnog betona, betona s 1
kg polimernih vlakana i mješavine s 5, 10 i 15 kg polimernih vlakana iz otpadnih guma.

Ključne reči: visoke temperature, mikroarmirani beton, reciklirana vlakna iz otpadnih guma.

1
PhD, University of Zagreb, Faculty of Civil Engineering, Kaciceva 26, 10 000 Zagreb, Croatia, jmarija@grad.hr
2
PhD, University of Zagreb, Faculty of Civil Eng., Kaciceva 26, 10 000 Zagreb, Croatia, abaricevic@grad.hr
3
PhD, University of Zagreb, Faculty of Civil Engineering, Kaciceva 26, 10 000 Zagreb, Croatia, mserdar@grad.hr
4
PhD student, University of Zagreb, Faculty of Civil Eng., Kaciceva 26, 10 000 Zagreb, Croatia, mpezer@grad.hr
5
Prof. PhD, University of Zagreb, Faculty of Civil Eng., Kaciceva 26, 10 000 Zagreb, Croatia, dubravka@grad.hr

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1. INTRODUCTION
Under the impact of fire, different physical, chemical and mechanical processes in
concrete can cause degradation of the mechanical properties and explosive spalling of
protective layer of the reinforcement [1]. The extent of reduction of mechanical
properties is controlled by the heating rate, the maximum temperature reached and
exposure time, but also by a number of concrete properties including aggregate type,
porosity, mineral additives used etc. Furthermore, during cooling of the concrete to
the regular environmental temperature, degradation of mechanical properties
continues up to 20% and the highest reduction is expected to be achieved up to one
week after fire depending of the geometry of the structure [2].
The risk of occurrence of an explosive spalling of protective layer can be reduced
or even completely eliminated by the addition of polypropylene (PP) fibers in the
concrete mixes. Polypropylene fibers melt at temperature of approx. 160°C and
evaporate at temperature of approx. 340°C, creating tiny channels in the concrete
material that allow pore pressure to be released [3,4]. Two different viewpoints exist
regarding the effect of polypropylene fibres on compressive strength with exposure to
high temperatures. According to [5,6] polypropylene fibres cause a quicker loss of
compressive strength, which is inconsistent with [7], who found that polypropylene
fibres benefit the residual strength of concrete after exposure to high temperatures.
With the development of environmental awareness, there is a growing interest to
find more efficient paths for waste management. Waste tyres present a specific type
of waste whose removal from the environment is mandatory. Tyres comprise roughly
80% rubber granules, reinforced with 15% steel and 5% polymer fibre reinforcement
(RTPF) (Figure 1). In the framework of FP7 project - Anagennisi, one of the task is to
identify suitable applications for recycled tyre polymer fibres (RTPF) in concrete [8,
9]. Preliminary research in the framework of aforementioned project showed that
melting of crystalline part of polymers comprising analysed textile fibre occurs in the
temperature range from 210 ºC to 260 ºC and furthermore studied specimens with
reused tyre polymer fibre at a dose equal to or above 2 kg/m3 did not spall during
exposure to hydrocarbon fire [10,11].

Figure 1 – Components left after tyre recycling: rubber granules, steel and polymer
fibres

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This study is focused on determining the influence of the high temperature on the
mechanical properties (compressive strength and modulus of elasticity, in particular)
remained after cooling of concrete specimens made with recycled tyre polymer fibres.

2. EXPERIMENTAL STUDY
2.1. Concrete compositions
Experimental program included five concrete mixes for laboratory testing: two as
reference mixes; plain concrete and fibre reinforced concrete (FRC) with 1 kg/m3 of
polypropylene fibres and three mixes with different amounts of RTPF per m3 of
concrete (5, 10 and 15 kg). All studied mixes were prepared with CEM II/B-M (S, V)
42,5 N, crushed limestone as an aggregate with maximum grain size of 16 mm and
polycarboxylic ether hyperplasticiser for achieving the target workability of mixes.
All mixes were designed to satisfy consistency class S4 (160 – 210 mm) in fresh
state. The concrete mix designs and properties in fresh state are shown in Table 1.
Таble 1- Mix compositions
3
Components (kg/m ) PC PP 5RTPF 10RTPF 15RTPF
Cement 370 370 370 370 370
Water 170 170 170 170 170
Superplasticizer 2.22 2.22 2.22 2.22 3.08
v/c 0.46 0.46 0.46 0.46 0.46
Fibres
Polypropylene -- 1 -- -- --
RTPF by GRP -- 5 10 15
Aggregate
0/4 mm 821.9 841.8 815.8 809.8 800.9
4/8 mm 383.1 364.7 380.3 377.5 366.3
8/16 mm 680.0 637.4 675.0 670.0 644.5
Fresh concrete properties
3
Density, kg/m 2.42 2.40 2.38 2.38 2.38
Air content, % 1.30 1.80 2.05 1.65 1.55

All materials were kept for 24 hours in the laboratory at a temperature of 20 ± 2°C.
The mixing procedure was as followed: first, the aggregates and the recycled tyre
polymer fibres were mixed together to ensure a good dispersion of fibres (Figure 2a).
Mixing was then proceeded for two minutes after adding half of the water (Figure
2b). To allow the aggregates to absorb the needed amount of water, the mixing was
stopped for about two minutes. The cement was then added and mixing started again
with continuous addition of the residual water and superplasticiser (Figure 2c). After
the insertion of all materials, the mixing continued for another two minutes.

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a) b) c)
Figure 2 –Mixing sequences
2.2. Specimens – curing, dimensions, heat treatment
Prepared specimens for experimental program were cylinders with dimensions of
Ø = 75 mm and L = 225 mm (i.e. slenderness equal to 3) recommended by RILEM
Technical Committee 200 [12]. All specimens were demoulded one day after casting
and were kept at a temperature of 20±2°C and relative humidity of 95% in a curing
room for another 27 days. After 28 days of curing, the specimens were dried up to
moisture content below 3% in order to avoid spalling of specimens during high
temperature treatment.
Temperature exposure followed also recommendations of the RILEM Technical
Committee 200. The specimens were exposed to four different temperature cycles in
an electrical furnace (with Tmax = 1350°C) in order that target temperature of 200°C,
400°C, 600° and 800°C be achieved throughout the specimens. The temperature cycle
consisted of:
1) heating at rate ΔT/Δt of 2°C/min up to target temperature achieved in the centre
of specimens,
2) slow cooling down to ambient temperature in the closed furnace in order to
avoid thermal shock to the concrete material.

a) b)
Figure 3 – a) position of the specimens in the furnace; b) position of thermocouple in the
specimen

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For each temperature, seven specimens from the same mix were exposed to
temperature cycle (Figure 3a), with one specimen being monitored for temperature.
The temperature was tracked with a K type thermocouple mounted in the centre of the
specimen before casting (Figure 3b). After cooling, specimens were moved to the
ordinary laboratory conditions (T=20-25°C; R.H.=50-70%) until testing.
2.3. Residual property tests
Compressive strength and modulus of elasticity were tested using hydraulic Toni
Technik testing machine with 3000 kN capacity and speed of applied load of 0.5
MPa/s. Elastic modulus is measured between 0.5 MPa and 1/3 of ultimate
compressive strength. Residual mechanical properties of thermal treated specimens
were performed 7 days after cooling down to the ambient temperature when the
highest reduction is expected. Three specimens were tested per each mix after each
temperature cycle.

3. RESULTS AND DISCUSSION

All the results obtained in this study are presented in Table 2 and Table 3. These
results are expressed as a mean and standard deviation value based on testing the
three specimens from the same mix and the same temperature treatment.
From the Tables 2 and 3 it can be observed that studied concrete mixes possessed
very similar initial values of compressive strength (with difference up to 6 MPa) and
modulus of elasticity (with difference up to 3 MPa).

Таble 2- Results of compressive strength testing, MPa

Temperature, °C
Mix
20 200 400 600
PC fθ 49.0 47.2 29.5 18.0
st.dev. 0.6 2.4 0.4 0.5
PPT fθ 46.5 46.4 27.9 13.9
st.dev. 0.3 0.5 0.7 0.2
5RTPF fθ 45.8 45.6 30.3 15.4
st.dev. 1.9 0.5 0.6 0.8
10RTPF fθ 42.7 46.5 27.4 14.5
st.dev. 1.7 0.6 0.6 0.5
15RTPF fθ 45.1 48.0 26.1 16.5
st.dev. 1.4 2.7 0.6 0.3

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Таble 3- Results of modulus elasticity testing, GPa
Temperature, °C
Mix
20 200 400 600
Eθ 39.4 31.7 15.3 9.8
PC
st.dev. 0.8 1.0 0.5 1.0
Eθ 37.7 29.2 14.9 7.6
PPT
st.dev. 0.2 0.3 0.8 0.5
Eθ 36.7 29.7 15.5 8.3
5RTPF
st.dev. 0.6 0.5 0.4 1.0
Eθ 38.0 30.5 14.4 8.7
10RTPF
st.dev. 0.6 1.8 0.5 0.4
Eθ 36.7 30.3 13.9 9.6
15RTPF
st.dev. 0.5 0.5 0.5 0.2

Seven days from the thermal treatment, testing of specimens that had been
exposed to temperature of 800°C could not be obtained, because specimens started to
crumble. This could be attributed to thermal decomposition of dolomite into lime
(CaO), periclase (MgO) and carbon dioxide (CO2) that is produced at the temperature
of about 700 °C. Absorbed an air moisture in the laboratory conditions, CaO turned
into Ca(OH)2 increasing its volume up to 44% and causing crumbling of specimens
[13].

a) b) c)
Figure 4 – Specimens of PC mix treated at 800°C after a) cooling to room temperature, b) 7
days of thermal treatment and c) 14 days of thermal treatment

In Figure 5 relative compressive strength is plotted against temperature of exposure.

Relative compressive strength is calculated by dividing compressive strength obtained
after temperature treatment at maximum reached temperature, θ, by compressive
strength obtained on unheated specimens (θ=20°C). Relative modulus of elasticity is
calculated analogously and presented in Figure 6.

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Figure 5 –Relative compressive strength versus temperature

Figure 6 –Relative modulus of elasticity versus temperature

From the Figures 5 and 6, it can be seen that studied mixes exhibited very similar
behaviour after thermal treatment. After 200°C, compressive strength of reinforced
concrete mixes (both with PP and RTPF fibres) remained unaffected or have slight
increase up to 9%, while had slight decrease of 4% in reference mix without fibres.
After higher temperatures, all mixes had similar decrease of compressive strength
with difference up to 7%. Comparing obtained results with recommendation for
residual strength of calcareous aggregate concretes given by HRN EN 1994-1-2 [14],
it can be concluded that this curve cannot be applied on studied mixes (Figure 5).

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As expected, modulus of elasticity was more affected by high temperature

exposure compared to compressive strength. All mixes showed almost the same
decrease with increasing temperature with difference within 6%.

4. CONCLUSIONS
This paper presents an experimental study, investigating the influence of polymer
fibres, extracted from waste tyres in concrete, on the residual mechanical properties
remained after high temperature exposure. Obtained results on studied RTPF mixes
were very similar with those obtained on mixes without fibres and with 1 kg of PP
fibres showing that inclusion of RTPF in dosage of 5, 10 and 15 kg per m3 of concrete
did not cause further reduction of mechanical properties, although this type of fibres
melt at temperature range from 210 ºC to 260 ºC and potentially increase permeability
of concrete.

ACKNOWLEDGMENTS
The research presented in this paper are conducted within the project "Anagennisi
- Innovative Reuse of all Tyre Components in Concrete" funded by the European
Commission under the 7th Framework Programme Environment topic. Authors
would like to thank Irena Pucic, PhD, Ruder Boskovic Institute, Division of Material
Chemistry for her contribution for qualitative and semi-quantitative analysis of a
sample of RTPF fibres. Authors would like to thank GUMIIMPEX for their support
and student Goran Degac for his contribution during experimental work.

REFERENCES
[1] Khoury, G.A., Anderberg, Y., Both, K., Fellinger, J., Hoj, N.P., Majorana, C.
2007. Fire design of concrete structures – materials, structures and modelling -
State of art report, Fib Bulletin 38, pp. 106.
[2] Hertz, K. D. 2005. Concrete Strength for Fire Safety Design. Magazine of
Concrete Research, 57 (8), pp. 445–53.
[3] Bildeau A., Kodur V.K.R., Hoff G.C. 2004. Optimisation of the type and amount
of polypropylene fibres for preventing the spalling of lightweight concrete
subjected to hydrocarbon fire, Cement Concrete Composite, 26 (2), pp. 163–174.
[4] Sullivan et al. 2004. Deterioration and spalling of high strength concrete under
fire, Offshore technology report 2001/074.
[5] Suhaendi, S.L., and Horiguchi, T. 2006. Effect of short fibres on residual
permeability and mechanical properties of hybrid fibre reinforced high strength
concrete after heat exposition, Cement and Concrete Research, 36 (9), pp. 1672-
1678.

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[6] Serdar, A., Yazici, H. 2008. High temperature resistance of normal strength and
autoclaved high strength mortars incorporated polypropilene and steel fibres,
Construction and Building Materials, 22 (4), pp. 504-512.
[7] Kalifa, P. et al. 2001. High-temperature behaviour of HPC with polypropylene
fibres: From spalling to microstructure., Cement and Concrete Research, 31 (10),
pp. 1487-1499.
[8] Serdar, M., Baricevic, A., Jelcic Rukavina, M., Bjegovic, D., Pezer, M., 2014,
D4.1: RTPF reinforced concrete, FP7 Project: Innovative Reuse of all Tyre
Components in Concrete.
[9] Baricevic, A., Bjegovic, D., Stirmer, N., Pezer, M., 2014, D4.2: RTPF Sprayed
concrete, FP7 Project: Innovative Reuse of all Tyre Components in Concrete.
[10] Serdar, M., Baricevic, A., Jelcic Rukavina, M., Pezer, M., Bjegović, D., Stirmer,
N., 2015, Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre
Polymer Fibres, International Journal of Polymer Science, Article in Press.
[11] Huang, S.-S., Angelakopoulos, H., Pilakoutas, K., Burgess, I. 2015. Reused tyre
polymer fibre for fire-spalling mitigation, F.Wald, I. Burgess, M. Jelcic
Rukavina, D. Bjegovic, K. Horova, eds., Proceedings of 4th International
Conference Application of Structural Fire Engineering, Dubrovnik, Croatia,
October 15-16, 2015, Czech Technical University in Prague, pp. 355-362.
[12] RILEM TC 200-HTC. 2007. Mechanical concrete properties at high
temperatures—modelling and applications, Part 1: Introduction—General
presentation, Materials and Structures, 40, pp. 841–853.
[13] Savva, A., Manita, P., Sideris, K. K. 2005. Influence of elevated temperatures on
the mechanical properties of blended cement concretes prepared with limestone
and siliceous aggregates, Cement and Concrete Composites, 27, pp. 239-248.
[14] HRN EN 1994-1-2:2012 Eurocode 4: Design of composite steel and concrete
structures -- Part 1-2: General rules -- Structural fire design (EN 1994-1-
2:2005+AC:2008).

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 SCIENTIFIC CONFERENCE
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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Dragica JEVTIĆ
Dimitrije ZAKIĆ2
Aleksandar SAVIĆ3
Aleksandar RADEVIĆ4
Marina AŠKRABIĆ5

INVESTIGATION OF PROPERTIES OF FRESH SELF-OMPACTING

CONCRETE MADE WITH FLY ASH
Abstract: Fly ash, as an industrial by-product with pozzolanic activity, has been used for decades as a
cement addition and mineral addition in concrete and mortar. This paper presents the effects of the use of
fly ash, as a partial replacement of mineral addition (limestone powder) in Self-Compacting Concrete
(SCC), on the properties of the concrete in the fresh state (slump flow, time t 500, V-funnel time, L-box,
segregation resistance). Considering the fact that the biggest disadvantage for the practical application of
fly ash lies in the variation of its properties, which depends on its composition and origin, differences in
the behaviour of fresh SCC mixtures with two different types of fly ash originating from two thermal
power plants "Kostolac" and "Kolubara" were investigated with particular attention.

Кey words: fly ash, SCC, mineral filler, fresh concrete properties

ISTRAŽIVANJE SVOJSTAVA SVEŽEG SAMOZBIJAJUĆEG

BETONA SA LETEĆIM PEPELOM
Rezime: Leteći pepeo se, kao industrijski nusprodukt sa pucolanskom aktivnošću, već duže vreme koristi
kao dodatak cementu i kao mineralni dodatak u betonima i malterima. U radu su prikazani efekti
upotrebe letećeg pepela, kao delimične zamene mineralnog dodatka (krečnjačkog brašna) u
samozbijajućim betonima (Self-Compacting Concrete – SCC), na svojstva betona u svežem stanju
(rasprostiranje sleganjem, vreme t500, vreme V-levka, L-boks, faktor segregacije). Imajući u vidu
činjenicu da najveći nedostatak za praktičnu primenu letećeg pepela leži u neujednačenosti njegovih
svojstava, koja zavise od njegovog sastava i porekla, sa posebnom pažnjom su praćene razlike u
ponašanju svežih SCC mešavina sa dve različite vrste letećeg pepela poreklom iz dve termoelektrane
''Kostolac'' i ''Kolubara''.

Ključne reči: leteći pepeo, SCC betoni, mineralni filer, svojstva svežeg betona

1
Ph.D. Full Professor, University of Belgrade, Faculty of Civil Engineering, dragica@imk.grf.bg.ac.rs
2
Ph.D. Assistant Professor, University of Belgrade, Faculty of Civil Engineering, dimmy@imk.grf.bg.ac.rs
3
Ph.D. Teaching Fellow, University of Belgrade, Faculty of Civil Engineering, sasha@imk.grf.bg.ac.rs
4
Teaching Assistant, University of Belgrade, Faculty of Civil Engineering, aradevic@grf.bg.ac.rs
5
Teaching Assistant, University of Belgrade, Faculty of Civil Engineering, amarina@imk.grf.bg.ac.rs

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1. INTRODUCTION
According to the principles of sustainable development, and possibility of their
implementation into civil engineering industry, it is of highest importance to
investigate the effects of the use of different industrial waste products as components
in concrete. Certainly, these activities must be done with respect to the modern
advances in technology and production of building materials.
Disposal of fly ash represents one of the biggest ecological problems nowadays. In
Serbia, over the years, large landfill areas of fly ash were formed around thermal
power plants, ranging more then 1500 hectares, mainly in the vicinity of nearby rivers
and arable fields. Naturally, the largest landfills in Serbia are located near the largest
power plants, Nikola Tesla in Obrenovac and the power plant in Kostolac[1]. Fly ash
was used in the world for decades as the mineral admixture in cement, because of its
pozzolanic properties. Based on the results from literature, use of fly ash, generally,
leads to the improved viscosity of concrete, lower risk of blocking and lower amount
of superplasticizer necessary to secure similar properties in fresh state [2].
On the other hand, with the advances in chemical industry, production of new
types of concrete mixtures became possible, due to the development of chemical
admixtures for different applications in cement composites. Self-Compacting
Concrete (SCC), introduced for the first time in Japan in mid 80’s, does not require
vibration, but it fills every part of the formwork and surrounds re-bars, even densely
spaced, simply by means of its own weight [3]. To achieve such behaviour of fresh
concrete, beside powerful superplasticizers (High Range Water Reducing Agents -
HRWRA) and VMA (Viscosity Modifying Agents), mineral fillers are used (usually
limestone powder) to improve the segregation resistance and the composition of
aggregate smaller than 0.125 mm. Basicaly, both cement (usually around 300-400
kg/m³ in SCC) and limestone powder (quantities ranging around 200-300 kg/m³) are
used as a powder component of SCC. Because of the fundamentally new concept of
SCC, the microstructure of the concrete, as a result of the hydration process, differs
compared to traditional, normally vibrated concrete [4]. The influence of limestone
powder on the paste properties include several effects: chemical, physical,
mineralogical, and filling [5].
Taking into account all the problems stated above, there is a high motivation to
investigate the influence of fly ash as a partial replacement of limestone powder on
the properties of fresh Self-Compacting Concrete (SCC) [6]. Use of this kind of
material as a mineral filler can lead to potentially positive effects both in physical and
mechanical (improving properties of concrete - pozzolanic effect) as well as in
ecological and economic sense [7].
It should be noted that the major problem of the application of the fly ash is that its
properties are variable, depending on the origin (influence of filters used in the power
plant, type of coal that was used, where and how fly ash was stored, etc). In this
paper, results of application of fly ash from two thermal power plants in Serbia
''Kolubarа'' and ''Kostolac'' will be presented and discussed.

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2. EXPERIMENTAL RESEARCH
The goal of the experimental research presented in this paper was to determine the
possibility of utilizing fly ash originated from Serbian thermal power plants, as a
partial substitution of limestone powder, while, at the same time, detaining properties
of SCC in fresh state. To achieve this goal, all three SCC abilities in fresh state had to
be considered and analyzed: filling ability, passing ability and segregation resistance
[8],[9],[10],[11]. This research was performed in the Laboratory for materials,
Institute for materials and structures, Faculty of Civil Engineering, University of
Belgrade.
2.1. Materials
The river aggregate, originated from Danube river and divided into fractions - I
(0/4), II (4/8) and III (8/16), was used for the production of SCC mixes. Specific
gravity of this aggregate was 2.641 g/cm3, while bulk density in loose state was
approximately 1.600 g/cm3.
Cement PC 42.5R Lafarge Beočin (without additions) was used. Specific gravity
of this cement amounted to 3.040 g/cm3. Limestone powder from "Granit Peščar"
Ljig, with the average diameter of 250 µm and specific gravity of 2.720 g/cm3, was
used as mineral filler in all mixtures.
Table 1 Chemical composition of fly ashes used
Parameter PP "Kostolac" PP "Kolubara"
SiO2 (%) 43.01 58.60
Al2O3 (%) 27.85 21.92
CaO (%) 9.09 6.12
Fe2O3 (%) 11.17 5.97
MgO (%) 1.95 1.77
K2O (%) 0.75 1.50
Na2O (%) 0.16 0.37
TiO2 (%) 0.82 0.49
Loss on ignition (%) 3.75 3.09
Pb (%) 0.0095 0.017
Cd (%) 0.0007 0.0005
Zu (%) 0.0087 0.0092
Cu (%) 0.0145 0.01
Cr (%) 0.0115 0.014
Ni (%) 0.012 0.013
Mn (%) 0.041 0.036
PO43- (%) 0.07 0.053
2-
SO4 (%) 1.34 <0.02
Cl- (%) <0.035 <0.035

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As it was already stated, fly ash used in this research originated from two different
power plants: "Kostolac" and "Kolubara". Specific gravities of these two types of fly
ash were similar: 2.210 g/cm3 (''Kostolac'') and 2.190 g/cm3 (''Kolubara''). Bulk
densities in loose state were as follows: 0.650 g/cm3 (''Kostolac'') and 0.690 g/cm3
(''Kolubara''). Chemical composition results for these two fly ashes are shown in
Table 1. The contents of reactive SiO2 and CaO were 43.01% and 9.09%, for fly ash
originating from ''Kostolac''. For fly ash originating from ''Kolubarа'', the contents of
reactive SiO2 and CaO were 58.60% and 6.12%. Grain size distribution curves of
these two fly ashes are shown in Figures 1 and 2.
Sampling and packing of fly ash was done by workers of the power plants. Fly ash
was transported in plastic bags and held protected from moisture and temperature
changes until experimental research. Fly ash was used in the delivered state, without
any additional means of preparation (sieving, crushing, etc), and it was added with
cement and powder, during the mixing process.

Figure 1. Grain size distribution curve of fly ash from "Kostolac"

Figure 2. Grain size distribution curve of fly ash from "Kolubara"

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The amount of fly ash was restricted to the maximum 20% of the total mass of
filler in SCC (excluding the mass of cement). In the case of tested concrete mixtures,
it means that mass of fly ash amounted to maximum 12% of the total mass of cement,
and maximum 2% of the total mass of SCC. Such (lower) quantities of fly ash were
chosen in order to reduce the influence of fly ash on the robustness of SCC mixtures,
and therefore to achieve higher stability in situations when change in properties (or
small changes of quantities) of components of SCC occur.
Polycarboxylate based superplasticizer Glenium Sky 690 (specific gravity 1.060
g/cm3), produced by BASF Construction Chemicals Spa Italia, was used both as a
HRWR and VMA in all concrete mixtures described in this paper.
Five series of SCC were made, with different quantities of fly ash. First mixture,
marked as E was made without fly ash, and it contained only limestone powder as
filler; therefore it was used as a reference mixture for comparison of fly ash influence
on fresh SCC properties. Other four mixtures contained fly ash, as a 10% and 20%
replacement of the same mass of limestone powder, and they can fall into two groups,
based on their origin, as shown in Table 2.

Table 2 Percentages of limestone powder replaced with fly ash from two power plants
Fly ash origin E LP1 LP2 LP3 LP4
''Kostolac'' power plant - 10 20 - -
''Kolubara'' power plant - - - 10 20

Amounts of cement and aggregate were equal for all SCC mixtures (cement 380
kg/m3 and aggregate 1700 kg/m3 – I fraction 840 kg/m3, II fraction 430 kg/m3 and III
fraction 430 kg/m3). Also, total amount of filler (total mass of limestone powder and
fly ash) was constantly 600 kg/m3. Water/cement ratio remained constant in all of the
mixtures (0.482). Also, in all of the SCC mixtures 2% of superplasticizer of the
cement mass (1.27% of the total powder mass) was added.

3. RESULTS AND DISCUSSION

Results of the tests conducted on fresh SCC mixtures are presented in Table 3
[12]. Results of the slump-flow test ranged between 664 mm and 761 mm for all of
the SCC mixtures and the time measured in V–funnel test (tv) ranged within the limits
of 9.7 s and 22.5 s. Fresh concrete temperatures were also measured and all fell
between 20 and 24°C. Generally, after perceiving the results stated above, it is clear
that all SCC mixtures belonged to the category SF2 according to the European
standard EN 206-9 [13], except concrete mixture E that had a slightly higher value
(761 mm). According to the same standard [13] all of the concrete mixtures belonged
to VS2/VF2 category with t500 (time measured from the moment of lifting the Abrams
cone until the concrete reaches diameter of 500 mm) longer than 2 s and tv longer than
9 s.

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According to the criteria with three bars in L-box, all of the concrete mixtures
reached class PL2 (ratio between the heights at the beginning and at the end of
horizontal part of L-box H2/H1>0.8) [13]. Segregation resistance of these SCC
mixtures can be classified as SR2 (≤15%) [13].
Table 3 Results of the tests conducted on fresh SCC mixtures
Fresh concrete property E LP1 LP2 LP3 LP4 Category
3
Fresh concrete density (kg/m ) 2397 2393 2376 2391 2370 -
SF2
Slump - flow test (mm) 761 738 700 701 664
(except E)
t500 (s) 2.62 5.00 6.72 5.71 10.91
VS2/VF2
tv (s) 9.73 16.87 20.17 15.92 22.46
L-box (H1/H2) 0.97 0.90 0.90 0.92 0.92 PL2
Segregation resistance SR (%) 3.5 2.9 2.5 3.0 2.0 SR2
Results from the tests conducted on fresh SCC mixtures with 10% of limestone
filler replaced with fly ash (LP1 and LP3) compared to the results gained on referent
mixture are shown on Figure 3. Similarly, comparison of the results from tests
conducted on SCC mixtures with 20% of limestone filler replaced with fly ash (LP2
and LP4) is shown on Figure 4.

Figure 3. Fresh SCC test results for the mixtures LP1 and LP3 (10% fly ash)
in comparison to E

Figure 4. Fresh SCC test results for the mixtures LP2 and LP4 (20% fly ash)
in comparison to E

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Fresh concrete density ranged from 2370 kg/m3 to 2397 kg/m3 for all of the SCC
mixtures; while the entrained air content ranged from 1.5% for LP3 mixture to 2.2%
for LP2 mixture (referent mixture E contained 1.9% of air).
As for the properties of the hardened concrete, compressive strength of the
referent mixture (E) reached 62 MPa (28 days) and 71.3 MPa (180 days), while the
values for concrete mixtures with fly ash at same ages ranged from 68.8 MPa (LP2)
to 72.4 MPa (LP4) after 28 days, and from 75.6 (LP1) MPa to 81.0 (LP2) MPa after
180 days.

4. CONCLUSION
This paper focuses on the influence of fly ash, as a partial replacement of
limestone filler in SCC mixtures, on fresh state concrete properties. Special attention
was paid to the comparison of behavior of mixtures with fly ash of different origin
(''Kostolac'' LP1 and LP2 and ''Kolubara'' LP3 and LP4). It is important to notice that
fly ash was used in its original state, without any additional actions of preparation,
which led to several negative effects. Firstly, it contained certain amount of oversized
grains, and certain amount of nonburned grains, which had negative effect on fresh
SCC properties. Conclusion from the literature, that addition of fly ash leads to
decrease in segregation and bleeding of concrete [14], was confirmed by visual
analysis, and by sieve method.
Also, the conclusion can be drown that the capacity of fresh concrete to flow
changed both with increase in the amount of fly ash (10%, 20%), and with change of
origin of fly ash used ("Kostolac" and "Kolubara"). Based on the comparison of the
effect of same fly ash amount but different origin (fly ashes from different thermal
power plants), it can be concluded that capacity of concrete to flow was decreasing
faster when fly ash originated from ''Kolubara'' thermal power plant. It is also
interesting to notice that (based on the results from slump-flow test) although
mixtures LP2 and LP4 reached smaller final diameters, it took them more time to
reach 500 mm diameter than for the mixtures LP1 and LP3.
Results of L-box test show that the passing ability of concrete decreased with the
presence of fly ash in the mixtures, regardless of the origin and regardless of the
amount (10%, 20%) of fly ash.
Although this paper focuses on the fresh state concrete properties, a short
overview of hardened state properties is added, having in mind application of
concrete. Generally, the 28-day compressive strengths of SCC mixtures with fly ash
were higher than the strength of the referent mixture. This is especially the case with
the mixture LP4 whose compressive strength was 16.8% higher than the referent
value. After 180 days, these values were approximately higher 6.6% (mixtures LP1
and LP3), and 12.3% (mixtures LP2 and LP4). These results lead us to the conclusion
that higher amount of fly ash imply higher compressive strength after 180 days,
regardless of the origin of fly ash used. This was expected, due to the pozzolanic

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effect of fly ash. Nevertheless, at earlier ages of concrete, SCC mixtures with fly ash
from ''Kolubara'' power plant showed higher compressive strengths.

ACKNOWLEDGEMENT
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry of Education, Science and Technological Development, Republic of
Serbia. This support is gratefully acknowledged.

REFERENCES
[1] Jevtić D, Zakić D, Savić A, Radević A (2012): The influence of fly ash on basic
properties of mortar and concrete, Scientific conference Planing, design,
construction and building renewal, Novi Sad, pp. 614-620,
[2] Sonebi M., Zhu W., Gibbs J.C. (2001): Bond of reinforcement in Self-
Compacting Concrete, Concrete, 35(7), pp. 26-28,
[3] European Project Group (2005): European Guidelines for Self-Compacting
Concrete: Specification, Production and Use,
[4] Tragardh J.: Microstructural features and related properties of Self-Compacting
Concrete, The 1st International RILEM Symposium on Self-Compacting
Concrete. Skarendahl.A., Petersson.O., editors, RILEM Publications S.A.R.L.,
France, pp. 175-186, (1999)
[5] De Shutter, G (2011): Effect of limestone filler as mineral addition in Self-
Compacting Concrete, 36th Conference on Our World in Concrete and
Structures, Singapore
[6] SRPS EN 450-1:2014 Leteći pepeo za beton – Deo 1: Definicija, specifikacije i
kriterijumi usaglašenosti
[7] Corinaldesi V, Moriconi G (2011): The role of industrial by-products in Self-
Compacting Concrete, Construction and Building Materials, 25, pp. 3181-3186,
[8] SRPS EN 12350-8:2012 Ispitivanje svežeg betona - Deo 8: Samougrađujući
beton – Ispitivanje rasprostiranja sleganjem, Institut za standardizaciju Srbije,
[9] SRPS EN 12350-9:2012 Ispitivanje svežeg betona - Deo 9: Samougrađujući
beton – Ispitivanje pomoću V-levka, Institut za standardizaciju Srbije,
[10] SRPS EN 12350-10:2012 Ispitivanje svežeg betona - Deo 10: Samougrađujući
beton – Ispitivanje pomoću L - kutije, Institut za standardizaciju Srbije,
[11] SRPS EN 12350-11:2012 Ispitivanje svežeg betona - Deo 11: Samougrađujući
beton – Ispitivanje segregacije pomoću sita, Institut za standardizaciju Srbije,

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[12] Savić, A: Istraživanje svojstava svežeg i očvrslog samozbijajućeg betona sa

mineralnim dodacima na bazi industrijskih nusprodukata, Doktorska disertacija,
Univerzitet u Beogradu, Građevinski fakultet, Beograd, mentori: prof. dr Dragica
Jevtić, prof. dr Tatjana Volkov Husović (2015)
[13] EN 206-9:2010 Concrete. Additional rules for Self-Compacting Concrete (SCC)
[14] Liu, M. (2009): Wider Application of Additions in Self-Compacting Concrete,
PhD thesis, Department of Civil, Environmental and Geomatic Engineering,
University College London

[225]
 SCIENTIFIC CONFERENCE
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iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Ivan LUKIĆ
Vlastimir RADONJANIN2
Mirjana MALEŠEV3
Vesna BULATOVIĆ4

INFLUENCE OF MINERAL ADMIXTURES ON WATER

ABSORPTION OF LIGHTWEIGHT AGGREGATE CONCRETE
Abstract: Experimental research presented in this paper was done with the aim to analyse the effect of
large amount of mineral admixtures (fly ash and metakaolin) as a partial replacement of cement on
capillary water absorption and water absorption under pressure of LWAC. Two lightweight aggregates
were selected for this study: lightweight expanded clay (“Leca-Laterlite” - Italy) and lightweight
expanded glass (“Poraver” - Germany). Obtained results showed an increase of capillary water
absorption and decrease of depth of water penetration under pressure of LWAC with high volume of
mineral admixture. It is also concluded that both types of lightweight aggregate have higher impact on
water absorption than selected mineral admixtures.

Key words: lightweight aggregate concrete, capillary porosity, water tightness, water absorption.

UTICAJ MINERALNIH DODATAKA NA UPIJANJE VODE

LAKOAGREGATNIH BETONA
Rezime: Eksperimentalno istraživanje prikazano u ovom radu je urađeno sa ciljem da se analizira uticaj
zamene dela cementa velikom količinom mineralnih dodataka (letećim pepelom i metakaoliom) na
kapilarno upijanje vode i upijanje vode pod pritiskom kod lakoagregatnih betona. Za istraživanje su
odabrani laki agregat na bazi ekspandirane gline (Leca-Laterlite" – Italija) i laki agregat na bazi
ekspandiranog stakla (Poraver" – Nemačka). Rezultati su pokazali da se zamenom dela cementa
mineralnim dodacima povećava kapilarna poroznost vezivne matrice, što za posledicu ima veće
kapilarno upijanje vode, dubina prodora vode pod pritiskom se smanjuje, dok je uticaj zamene dela
cementa mineralnim dodacima na količinu upijene vode pod pritiskom, mnogo je manji od uticaja
svojstava lakog agregata.

Ključne reči: laki agregat, lakoagregatni beton, kapilarna poroznost, vodonepropusnost, upijanje vode

1
PhD, Teaching Assistant, University of Novi Sad, Faculty of Technical Sciences, e-mail: lookic@uns.ac.rs
2
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: radonv@uns.ac.rs
3
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: miram@uns.ac.rs
4
MSc, Assistant, University of Novi Sad, Faculty of Technical Sciences, e-mail: vesnam@uns.ac.rs

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1. INTRODUCTION
Water absorption is one of the features that are directly related to the durability of
concrete and depends on several factors: the degree of hydration of cement, porosity,
pore structure and properties of cement and aggregates [1]. The possibility of water
penetration into the concrete structure defines the speed and extent of penetration of
aggressive substances or ions in, or through, the concrete mass, and thus the speed
and degree of deterioration.
Most of lightweight aggregate concretes (LWAC) show greater absorption than
normal concrete, which can be explained by the very high porosity of lightweight
aggregate, but, absorption is not as much greater as would be expected [2]. The water
penetration is caused by the presence of defects in the structure of concrete. In normal
concrete, interfacialbtransition zone is a "weak spot" due to a higher amount of
calcium hydroxide. Small tensile strength of transit zones further increases the risk of
cracking and increase the permeability of concrete. In lightweight concrete, texture
and porosity of the surface aggregates provide a good bond between aggregate and
cement matrix. During the mixing of fresh concrete, part of the water is absorbed by
lightweight aggregate, which leads to a reduction of water-cement ratio in the
transition zone. This means that, although aggregates are porous, they are surrounded
with less permeable cement matrix. Also, the lightweight aggregate deformability is
higher compared to conventional, natural aggregate, while the difference in stiffness
between aggregate and cement matrix is much smaller, so the possibility of
occurrence of micro-cracks due to shrinkage is lower [3].
Water absorption is closely related to the amount of water in the concrete, and it is
usually higher in LWAC than that of normal concrete [4]. Larger amounts of water
and lower permeability of cement matrix of LWAC have an impact on the extension
of the drying time of concrete [5]. This is of particular importance for the internal
curing because it improves hydration which results in a dense microstructure [6] [7]
or better transition zone.

2. EXPERIMENTAL RESEARCH
Experimental research presented in this paper was done with the aim to analyse the
effect of use of a large amount of mineral admixtures(fly ash and metakaoliom) as a
partial replacement of cement on capillary water absorption and water absorption
under pressure of LWAC.
For the purpose of research, two types of commercial lightweight aggregates that
differ in physical and mechanical properties were chosen:
• Lightweight expanded clay aggregate: „Leca-Laterlite" – Italy;
• Lightweight aggregate - expanded recycled glass: „Poraver" – Germany.

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2.1. Component materials

Component materials used in this study are:
3
• CEM I 42.5R ("Lafarge" Beocin Cement Factory, γs=3100kg/m );
• River aggregate RA (fractions 0/4mm, 4/8mm and 8/16mm);
• Lightweight aggregate „Leca-Laterlite" (0/15 and 4/15mm, Figure 1);
• Lightweight aggregate „Poraver" (fractions 2/4mm and 4/8mm, Figure 2);
• Fly ash (type "V", thermal power plant "Nikola Tesla B" Obrenovac – Serbia,
γs=2100kg/m3);
3
• Metakaolin HR ("Metamax" – USA, γs=2500kg/m );
• Superplasticizer (HRWRA+SRA, "Sika ViscoCrete 4000BP", „Sika
ViscoCrete 3077“ or „Sika ViscoCrete 5500“ γs≈1080kg/m3);
• Tap water.
Grain-size composition, bulk density and water absorption of the river and
lightweight aggregate are tested according to EN1097-3 [8], EN1097-6 [9], EN933-1
[10] and EN13055 -1 [11] standards. The results are shown in Tables 1 and 2.

Table 1 - Grain-size composition of used aggregates (%)

Bottom 0,125 0,25 0,5 1 2 4 8 16 31,5
RA 0/4mm 0.0 1.6 21.7 52.7 65.6 79.0 95.8 100 100 100
RA 4/8mm 0.0 0 0 0 0 1.4 15.1 91.8 100 100
RA 8/16mm 0 0 0 0 0 0 1.6 22.2 95.7 100
Leca 2/3mm 0 0 0 0 0.6 12.3 88.7 100 100 100
Poraver 0/4mm 0 0 0 0 0 5.1 99.0 100 100 100
Poraver 4/8mm 0 0 0 0 0 0 1.4 98.9 100 100

Table 2 - Properties of used aggregates

Water
The absorption The
Type of apparent membrane Pore size
after 30 min Pore shape
aggregate bulk density thickness [μm]
[kg/m3] [% by [μm]
volume]
RA 2660 -
Leca 4/15mm 1020 4,7 5-13 0.2-1000 round
Poraver 2/4mm 300 6,9
2-6 5-250 round
Poraver 4/8mm 291 5,8

Figure 1. Lightweight aggregate Figure 2. Lightweight aggregate „Poraver“

„Leca-Laterlite“

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In addition to standard tests of aggregate, SEM microstructural analysis was

carried out. A grains appearance is shown in Figures 3 and 4 [12], and the analysis
results are given in Table 2.

Figure 3. SEM picture of aggregate „Leca- Figure 4. SEM picture of aggregate

Laterlite“ 4/15 (magnified 1000x) „Poraver“ 4/8 (magnified 1000x)

Differences in the physical and mechanical properties of these two types of

aggregates can be explained by analyzing the microstructure of the aggregate grains
[13]. The greater membrane thickness of the aggregate "Leca-Laterlite" (from 5 μm to
13 μm) than of the aggregate "Poraver" (from 2 μm to 6 μm) and smaller pore size of
aggregate "Leca-Laterlite" (dominant from 25 μm to 80 μm) than of aggregate
"Poraver" (predominantly from 100 μm to 250 μm) lead to reduction of grinding, ie.
greater strength of aggregate "Leca-Laterlite". On the other hand, the higher porosity
of "Poraver" aggregate leads to significantly lower bulk density.

2.2. Concrete mix design

For the realization of the planned research, three groups of concrete were made:
the two groups were prepared with selected types of lightweight aggregates and one
group with coarse river aggregate. Within each group of lightweight aggregate
concrete, the quantities of cement and mineral admixtures were varied. In concretes
with high amount of mineral admixtures, 50% of cement absolut volume was
substituted as follows:
• 40% of the cement absolut volume was substituted with fly ash;
• 10% of the cement absolut volume was substituted with metakaolin.
The composition of concrete mixtures was designed based on the following initial
conditions:
• the same consistency, expressed with settlement after 15 minutes
(∆h=12±2cm, S3 according to EN 206 [14]);
3
• absolute volume of binder and water ~0.3m , absolute volume of aggregate
3
~0.7m ;

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• grain-size composition of a mixture of aggregates is in the form of a

continuous curve;
• additional amount of water was determined by water absorption of lightweight
aggregate after 30min;
• the amount of super-plasticizer is based on the need to achieve the required
consistency;
• effective water-binder ratio was 0.4-0.5 depending on the binder quantity.
Based on the initial conditions, the composition of concrete mixtures was defined.
Total of 9 types of concrete mixtures have been designed and tested. Aggregate Leca-
Laterlite was used in 4 concrete mixtures, Poraver also in 4 concrete mixtures, while
river aggregate was used in one referent mixture. Table 3 presents compositions and
labels of concrete mixtures that have been adopted in order to simplify comparative
analysis.
Table 3 - Quantities of component materials in kg/m3
Concrete type
Leca-Laterlite Poraver Normal
LLK1 LLK4 LLK5 LLK6 LP1 LP4 LP5 LP6 NK
CEM I 42,5R 450 400 244 278 450 400 244 278 450
Effective water 180 180 183 163 180 180 183 163 180
Additional water 15.3 15.6 15.3 15.3 14.2 14.3 14.2 14.2 -
RA 0/4mm 940 955 940 940 990 991 990 990 855
RA 4/8mm - - - - 150 152 150 150 251
RA 8/16mm - - - - - - - - 628
Leca 4/15mm 333 339 333 333 - - - - -
Poraver 2/4 - - - - 46 46.4 46 46 -
Poraver 4/8 - - - - 18 18.3 18 18 -
Fly ash - - 97.6 111.4 - - 97.6 111.4 -
Metakaolin - - 22.4 27.8 - - 22.4 27.8 -
Superplasticizer 3.15 2.4 2.56 2.5 5.8 5.2 4.8 7 3.15
ω=mw/(mc+mf+mmk) 0.4 0.45 0.5 0.4 0.4 0.45 0.5 0.4 0.4
ωef*=mw/(mc+k(mf+mmk)) 0.4 0.45 0.63 0.49 0.4 0.45 0.63 0.49 0.4
* effective water/binder ratio is based on the “efficiency coefficient” according to EN 206 [14]
The concrete properties analyzed in this study are capillary water absorption and
water absorption under pressure of LWAC.
2.3. Testing procedures
Water absorption was conducted in two ways:
• Capillary water absorption according to SRPS U.M8.300 [15] (Fig. 5);
• Water absorption under pressure according to EN 12390-8 [16] (Fig. 6).
Before testing, samples were conditioned as follows: first 24h in moulds at
T≈20±2°, 13 days in water at T≈20±2° and 14 days at the standard laboratory air
temperature and humidity (T≈20±2°, φ≈60%).

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Figure 6. Capillary water absorption setup

Figure 5. Water absorption under pressure

setup
For the capillary water absorption test, specimen surface area subjected to water
was cca 225cm2. After weighing the dry specimens, they were put on rods in a water
tank in such way that they were immersed for no more than 5 mm. To obtain
unidirectional flow, side surface of concrete specimens were covered with a
waterproofing membrane. Measurements were conducted after 1, 5, 15, 30 minutes, 1,
4, 9, 25 and 49 hours. The results were expressed as water absorption in kg/m2 and
presented values are average of three specimens.
2.4. Test results and discusion
2.4.1. Capillary water absorption
The results of capillary water absorption of concrete (expressed in kg/m2), and the
calculated values of the coefficient of capillary water absorption (based on the
amount of capillary water absorbed in the period up to 25 hours) are given in Figures
7 and 8. capillary water absorption and capillary water absorption coefficient are
determined according to the expressions (1) and (2).
,

 
/ 

(1)

, 
  
/ /  (2)
√
where:
• Uk – capillary water absorption;
• mv,k – mass of capillary absorbed water;
• Ai – capillary water absorption coefficient;
• Uk,25 – capillary water absorption after t=25h.

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1,8

1,6
Capillary water absorption [kg/m2]

NK
1,4 LLK-1
1,2 LP-1
LLK-4
1
LP-4
0,8
LLK-5
0,6 LP-5
0,4 LLK-6
LP-6
0,2

0
0 1 2 3 4 5 6 7 8 9
1/2
t [h ]1/2

Figure 7. Capillary water absorption of normal concrete and LWAC

0,3
Capillary water absorption

0,25
coefficient [kg/m2 h1/2]

0,2

0,15

0,1

0,05

0
NK LLK-1 LP-1 LLK-4 LP-4 LLK-5 LP-5 LLK-6 LP-6
Vrsta betona
Figure 8. Capillary water absorption coefficient of normal concrete and LWAC

The lowest capillary water absorption shows concrete NK as a result of the applied
types of aggregates. For the preparation of the concrete mixture river aggregate that is
considered to be non-porous was used. Other types of concrete, which were made
with lightweight aggregate, show greater capillary water absorption.
Analyzing capillary water absorption of concretes with different water/binder ratio
can be concluded that with increasing of water-binder ratio increases the amount of
capillary absorbed water.
The values of capillary absorption of water depends on the type of applied binder.
Concrete made only with cement CEM I showed less capillary absorption compared
to concrete made with CEM I+fly ash+metakaolin. As all concretes have

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approximately the same volume of binder matrix, these results can be explained by
faster hydration and therefore less capillary porosity of binder matrix made only with
portland cement.
Significant differences in the water absorption of concrete with "Leca Laterlite"
and "Poraver" lightweight aggregate can be attributed to the higher porosity of mortar
component of concrete LP due to the substitution of a part of the fine river aggregate
with fine lightweight aggregate, and larger share of fine aggregate in concrete mix.
The same conclusions can be drawn about the kinetics of water absorption by
analysis of coefficient of capillary absorption. The coefficient of capillary absorption
of water close to reference concrete (NK) have concrete with lightweight aggregate
"Leca-Laterlite" and with the highest quality cement matrix (LLK-1). Other concretes
from this group have a coefficient of capillary water absorption similar to concrete
with lightweight aggregate "Poraver" and best binder matrix.
Concretes with high amount of mineral admixtures have significantly higher
coefficient of capillary absorption compared to NK because of cobination of higher
aggregate porosity and binder matrix porosity. Further comparation of coefficient of
capillary water absorption (CWA) has been done separately for LWACs with
"Poraver" aggregate. It can be seen that difference between LP1 and LP6 (with MA)
is not significant. Also, difference between LP4 and LP5 (with MA) is very small
(Fig. 8). It leads to the conclusion that in LWAC wih "Poraver" aggregate mineral
admixture has not negative influence on capillary water absorption. On the other
hand, in LWACs with "Leca-Laterlite" aggregate, concretes with mineral admihture
have higher values of coefficient of capillary water absorption.

2.4.2. Water absorption under pressure

Results of measuring the depth of penetration (in mm) and the quantity of
absorbed water (in kg/m2) are given in Figure 9. The water absorption is calculated
according to the expression:
  


    (3)
 
where:
• Usr – average water absorption in kg/m2;
• m1 – initial mass of the sample;
• m2 – mass of the sample after test;
• A – concrete surface exposed to water under pressure (circle, D≈7.5cm).

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6,0 30
Water absorption under pressure V-II
Water absorption under pressure [kg/m2]

Depth of water penetration

Depth of water penetration[mm]

5,0 25

V-III
4,0 20

3,0 15

2,0 10

1,0 5

0,0 0
NK LLK-1 LLK-4 LLK-5 LLK-6 LP-1 LP-4 LP-5 LP-6
Concrete type
Figure 9. Water absorption and depth of water penetration under of normal
concrete and LWAC

Comparing depths of penetration of water under pressure with the criteria for the
evaluation of watertightness class (acording to SRPS U.M1.206-1/1) it can be
concluded that concretes LLK-4, LLK-5, LLK-6, LP-1 and LP-6 belong to
watertightness class V-III, for which the maximum depth of penetration is limited to
20mm, while concretes NK, LLK-1, LP-4 and LP-5 belong to the class V-II, for
which maximum depth of penetration is limited to 30mm.
Analysing influence of water/binder ratio and binder type to depth of penetration
of water under pressure can be concluded that concretes in which part of the cement
was replaced with high amount of mineral admixtures have generally lower values of
the depth of water penetration. Such results indicate reduction of binder matrix
porosity by replacing part of cement with mineral admixtures.
Compared to ordinary concrete NK, average water absorption under pressure of
concrete with lightweight aggregate is generally higher. The reason for the increased
absorption of LWAC can be found in a large open porosity of lightweight aggregate,
unlike natural river aggregate that is considered to be non-porous.
The amount of absorbed water under pressure in concrete LLK suggest that
replacing some of the cement with mineral admixtures reduces water absorption,
while at the concrete LP increases, which leads to the conclusion that the influence of
mineral admixtures or the quality of the binding matrix is smaller than the influence
of properties lightweight aggregate.

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3. CONCLUSION
Based on the results of experimental research the following can be concluded:
• Lightweight aggregate concrete have greater capillary water absorption than
ordinary concrete as a consequence of the use of porous aggregate (unlike the
river aggregate, which is considered to be non-porous aggregate).
• Substitution of part of cement with mineral admixtures increases capillary
porosity of binder matrix which results in greater capillary water absorption at
the early age. Since mineral admixtures reduces rate of cement hydration due
to pozzolanic properties of admixtures, capillary porosity should, also, be
determined at the later age, when pozzolanic activity gets to its extent.
• Concrete with lightweight aggregate based on expanded glass have the highest
capillary porosity as a result of substitution of a part of the fine river aggregate
with fine lightweight aggregate and a larger proportion of fine aggregate in
concrete mix.
• Compared to ordinary concrete, the average water absorption under pressure of
LWAC is generally higher.
• Substitution of part of cement with mineral admixtures reduces the depth of
penetration of water under pressure.
• Compared to ordinary concrete, the depth of penetration water under pressure
of LWAC is generally lower. According to the depth of penetration of water
under pressure, LWAC belongs to watertightness classes V-II and V-III
according to SRPS U.M1.206-1/1
• Both types of lightweight aggregate have higher impact on water absorption
than selected mineral admixtures.

ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

REFERENCES
[1] Muravljov M. Osnovi teorije i tehnologije betona Beograd: Građevinska knjiga;
2000.
[2] Newman J, Owens P. Advanced Concrete Technology - Processes Newman J,
Choo BS, editors. Oxford: Elsevier Ltd.; 2003.
[3] EuroLightCon. LWAC Material Properties: State of the Art. ; 1998.
[4] FIP. Manual of Lightweight Aggregate Concrete. 2nd ed.: Surrey University
Press; 1983.

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[5] Smeplass S. Drying of LWAC. In Helland S, Holand I, Smeplass S, editors.

Second International Symposium on on Structural Lightweight Aggregate
Concrete; 2000; Kristiansand, Norway: Helli Grafisk. p. 833–843.
[6] Henkensiefken R, Castro J, Bentz D, Nantung T, Weiss J. Water absorption in
internally cured mortar made with water-filled lightweight aggregate. Cement
and Concrete Research. 2009 October; 39(10): p. 883–892.
[7] Bentz DP, Halleck PM, Grader AS, Roberts JW. Water Movement during
Internal Curing: Direct Observation Using X-ray Microtomography. Concrete
International. 2006 October; 28(10): p. 39-45.
[8] ISS. SRPS EN 1097-3: Ispitivanja mehaničkih i fizičkih svojstava agregata - Deo
3: Određivanje šupljina i zapreminske mase u rastresitom stanju. Beograd:
Institut za standardizaciju Srbije; 2009.
[9] ISS. SRPS EN 1097-6: Ispitivanje mehaničkih i fizičkih svojstava agregata - Deo
6: Određivanje stvarne zapreminske mase i upijanja vode. Beograd: Institut za
standardizaciju Srbije; 2007.
[10] ISS. SRPS EN 933-1: Ispitivanje geometrijskih svojstava agregata — Deo 1:
Određivanje granulometrijskog sastava — Metoda prosejavanja. Beograd:
Institut za standardizaciju Srbije; 2013.
[11] ISS. SRPS EN 13055-1: Laki agregati - Deo 1: Laki agregati za beton, malter i
injekcione smese. Beograd: Institut za standardizaciju Srbije; 2007.
[12] Lukić I, Malešev M, Radonjanin V, Bulatović V, Vukoslavčević S, Šupić S.
Lightweight Aggregate Concrete With High Amount Of Mineral Admixtures. In
16th International symposium of MASE; 2015; Ohrid: Macedonian Association
of Structrural Engineers. p. 349-358.
[13] Lukić I. A comparative analysis of the basic properties of structural concrete
made with different types of lightweight aggregates. PhD Thesis. Novi Sad:;
2015.
[14] ISS. SRPS EN 206-1: Beton — Deo 1: Specifikacija, performanse, proizvodnja i
usaglašenost. Beograd: Institut za standardizaciju Srbije; 2011.
[15] ISS. SRPS U.M8.300: Merenje kapilarnog upijanja vode i utvrđivanje
koeficijenta kapilarnog upijanja vode gradevinskih materijala. Beograd: Institut
za standardizaciju Srbije; 1985.
[16] ISS. SRPS EN 12390-8: Ispitivanje očvrslog betona - Deo 8: Dubina penetracije
vode pod pritiskom. Beograd: Institut za standardizaciju Srbije; 2010.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Mirjana MALEŠEV
Vlastimir RADONJANIN2
Miroslava RADEKA3
Slobodan ŠUPIĆ4
Suzana VUKOSLAVČEVIĆ5

THE INFLUENCE OF BIOMASS ASH ON PHYSICAL AND

MECHANICAL PROPERTIES OF CEMENT MORTARS
Abstract: Utilization of biomass ashes as building material or as raw material in the manufacture of
building products can be regarded as a sustainable form of utilization as the use of ashes saves the use of
non-renewable resources, reduces the amount of agricultural waste and CO2 emission. Significant
agricultural residues of field production in Serbia are: wheat straw, maize stover and cobs, soy straw
straw and oil rape straw. This paper presents an experimental research of influence of wheat straw ash
and soy straw ash on physical and mechanical properties of cement mortars. Comparative analyses of
compressive strength and drying shrinkage of cement mortars was conducted. Content of ashes was
varied from 10 to 30% in relation to cement mass. The results suggest that the biomass ashes can be used
in mortars as substitutes of cement without compromising their mechanical performances.
Кey words: biomass, ash, mortars, physical and mechanical properties.

ISPITIVANJE UTICAJA BIOPEPELA NA FIZIČKA I MEHANIČKA

SVOJSTVA CEMENTNIH MALTERA
Rezime: Korišćenje pepela od biomase kao građevinskog materijala ili sirovine u proizvodnji
građevinskih proizvoda zadovoljava principe održivog razvoja, jer njegova upotreba smanjuje korišćenje
neobnovljivih izvora, smanjuje količinu otpada od poljoprivredne proizvodnje i redukuje emisiju CO 2.
Značajni ostaci poljoprivredne proizvodnje u Srbiji su: pšenična slama, kukuruzovina, sojina slama i
slama od uljane repe. Ovaj rad obuhvata eksperimentalno istraživanje uticaja pepela nastalog
sagorevanjem pšenične i sojine slame na fizička i mehanička svojstva cementnih maltera. Urađena je
komparativna analiza čvrstoće pri pritisku i skupljanja pri sušenju cementnih maltera. Sadržaj pepela je
variran u količinama od 10 do 30% u odnosu na masu cementa. Rezultati pokazuju da se biopepeo može
uspešno koristiti kao zamena dela cementa u malterima, bez ugrožavanja njihovih mehaničkih
karakteristika.
Ključne reči: biomasa, pepeo, malteri, fizička i mehanička svojstva.

1
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, miram@uns.ac.rs
2
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, radonv@uns.ac.rs
3
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, mirka@uns.ac.rs
4
Ass. MSc CE, University of Novi Sad, Faculty of Technical Sciences, ssupic@uns.ac.rs
5
Ass. MSc CE, University of Novi Sad, Faculty of Technical Sciences, suzanav@uns.ac.rs

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1. INTRODUCTION
Agroindustry is a sector that mainly serves the needs of food supply, both animal
and human consumption. It has been recently observed that there is a great potential
for some of these industries, such as sugar, wood, and others to share part of their
crops to the production of biomass for power generation. As a result, studies of how
to turn these plants into energy sources have constantly been done to increase power
energy efficiency. However, once the plants have been burned to produce energy, the
product of such combustion is a residue with variable content of organic and
inorganic material; these residues are the biomass ashes (BA) and in most of cases
those residues do not have a defined application; thus, confinement is regularly
practiced. BA contains different features and their properties must be established to
determine the possible uses or final disposal [1].
Utilization of ashes from biomass is part of sustainable power generation and
contributes to the green image, while landfill of biomass ashes may be interpreted
as wasting of valuable nutrients. Utilization of biomass ashes as building material
or as raw material in the manufacture of building products can be regarded as a
sustainable form of utilization when the use of ashes saves the use of non-renewable
resources [2].
Therefore, substitution of cement in mortar and concrete with the ashes produced
by the combustion of biomass (containing Al, Ca, Fe, Mg, Na, P, Si), as CO 2 neutral
fuel, could reduce the impact on global warming, give a new use-value and the
possibility of economic evaluation of biomass ash as a raw material. All these effects
would represent a strong incentive for creating the conditions for integrated
management using about 250 000 t/year of biomass ashes from agriculture in Serbia.
Recently, a number of relatively new supplementary cementitious materials, such
as rice husk ash, sewage sludge ash, and oil shale ash, have undergone extensive
research. Significant agricultural residues of field production in Serbia are: wheat
straw, maize stover and cobs, soy straw and oil rape straw.
Wheat straw ash (WSA) is obtained by the grinding of wheat straw burned in
controlled electrical furnace and then cooled rapidly. The amorphous SiO2 content of
this ash is high and it can be accepted as a pozzolanic material. WSA is finer than
Portland cement (PC). It is known that fine pozzolans improve the properties of
cement-based materials due to their pozzolanic properties and filler effect [3].
Soy straw is an agricultural byproduct that remains after soybean harvest. It is
comprised mainly by dry leaves, husks and stalks that are mechanically removed
during soybean crop. Large volumes of this material are generally abandoned or burnt
in the fields causing environmental pollution. In addition to its high polysaccharide
content, soy straw does not require an extensive grinding process prior to
pretreatment as some other lignocellulosic material. Therefore, it is a renewable and
low-cost material [4].

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This paper is second paper that deal with this topic and together with paper [3]
represent good base for further research of biomass ash possible application. Based on
the results obtained in first paper, by investigating pozzolanic properties of five
different types of ash, wheat straw ash and soy straw ash were selecteded for further
investigation. Testing of physical and mechanical properties of mortars containing
these ashes has been carried out in this research.

2. EXPERIMENTAL INVESTIGATION

2.1. Component materials and the composition of the tested mortar

For experimental investigation of influence of biomass ash on the basic properties

of cement mortars, the following component materials were used:
 Portland cement CEM I 42,5R (Lafarge-BFC Serbia),
 Wheat straw ash (Figure 1), (fineness: 0-0,25mm)
 Soy straw ash (Figure 2), (fineness: 0-0,25mm)
 Standard sand in accordance with EN 196-1,
 Superplasticizer (HRWRA) (SikaViscoCrete 3070, Sika Switzerland),
 Distillated water.

Figure 1 – Wheat straw ash, divided in Figure 2 – Soy straw ash, divided in
fractions fractions
The experimental study was carried out on seven mortar mixtures. Referent mortar
(E) was prepared with Portland cement as binder, standard sand and water according
to EN 196-1. In the next three types of mortars (P10, P20 and P30) the part of cement
was replaiced with 10%, 20% and 30% of wheat ash. In remaining three mortars
(PS10, PS20 and PS30) the part of cement was replaiced with combined wheat and
soy straw ash, likewise.
The mix proportions of these seven mortars are given in Table 1.

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Table 1. Marks and compositions of mortar mixtures

Mortar type E P10 P20 P30 PS10 PS20 PS30
Cement, g 450 405 360 315 405 360 315
Wheat ash, g - 45 90 135 - - -
Wheat and soy ash, g - - - - 45 90 135
Water, g 225 225 225 225 225 225 225
Standard sand, g 1350 1350 1350 1350 1350 1350 1350
Superplasticizer, g - 1,35 1,35 2,025 1,35 1,35 1,35

2.2. Methods and testing results

The following properties were investigated on hardened mortars:

 Pore size distribution at the age of 28 days,
 Compressive strength at different ages (7, 28, 60 and 90 days)
 Shrinkage of up to 60 days.
The compressive strength and shrinkage of mortars were tested on standard prisms
with dimensions 4cmx4cmx16cm.The pore size distribution were tested on fragments
of prisms.

2.2.1. Pore size distribution

Pore-size distribution of selected mortar types was analyzed by mercury intrusion
porosimetry. Total porosity of tested mortar types is presented in Table 2. Results
indicate that the total porosity increases as content of wheat straw ash and soy straw
ash increases, which should cause an impact on the mechanical properties and
permeability of these mortars. The pore-size distribution, in Figure 3, indicates that
the dominant pores interval for all samples is from 0 to 0.06µm. Soy straw ash
contributes to the larger pores quantity increase, while wheat straw ash decreases their
quantity, compared to the referent mortar. However, due to the pozzolanic properties
of the ashes, as content of C-S-H products increases, content of pores smaller than
30nm is also increased. This pore size is too small to have an adverse effect on the
strength and permeability of the hydrated cement paste. However, these small voids
are a real source of water, and its removal under certain conditions may contribute to
drying shrinkage and creep.
Table 2. Total porosity of tested mortar types
Mortar type E P10 P20 P30 PS10 PS20 PS30

Total porosity (%) 6.98 9.5 10.89 13.32 8.43 9.68 13.36

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Figure 3 – Pore-size distribution determined by Mercury intrusion porosimetry

2.2.2. Compressive strength

Samples for the testing of compressive strength were cured in water to the
anticipated age. Compressive strength of all types of mortars is tested according to
EN 196-1. Compression testing machine with range of 150 kN was used. Mean
values of compressive strength of tested mortars for different ages are shown in Table
3. Change of compressive strength of different mortar types in relation to the age is
shown in Figure 4.
Table 3. Compressive strengths of tested mortar types
Mortar type E P10 P20 P30 PS10 PS20 PS30

fcm,28 (MPa) 46.00 45,31 43.62 36.98 45,52 42,19 36,88

fcm,60 (MPa) 52,29 49,58 46,04 43,54 48,96 46,35 41,25
fcm,90 (MPa) 52,50 53,33 52,71 45,73 52,92 50,94 44,10
Compressive strength, MPa

E
P10
P20
P30
PS10
PS20
PS30

Age, days
Figure 4 - Change of compressive strength of different mortar types in relation to the age

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Comparing the values of compressive strength at the age of 28 days, it is obvious

that by increasing of ash content the compressive strength of mortars is decreased.
However, mortars P10 and PS10 showed the compressive strength negligible smaller
then referent mortar.
Based on the trend of the results, shown in Figure 4, it can be concluded that
referent cement mortar gained most of its compressive strength by the age of 60 days.
Afterwards, compressive strength convergates to final value. On the other hand, due
to the pozzolanic activities, all types of mortars containing wheat straw and soy straw
ash show the increase of compressive strength over time. At the age of 90 days,
mortars P10, P20 and PS10 gained compressive strengths even higher then referent
mortar. Therefore, the beneficial effect of adding biomass ash in cement mortars is
more noticeable at later ages.
Changes of compressive strength of testing mortars (P10, P20, P30, PS10, PS20
and PS30) in relation to corresponding strength of reference mortar (E) are shown in
Figure 5.
110
age 28 days age 56 days age 91 ages
Change of strength in relation to "E", %

100
90
80
70
60
50
40
30
20
10
0
E P10 P20 P30 PS10 PS20 PS30
Figure 5 - Changes of compressive strength of testing mortars

2.2.3. Drying shrinkage

Drying shrinkage of all investigated mortars are tested in accordance with method
described in SRPS B.C8.029. Measurements were conducted after 3, 4, 7, 14, 21, 28,
35, 42, 49 and 56 days. For measuring of length changes of mortar samples, length
comparator with base of 160mm was used. The samples were cured in climatic
chamber at the temperature of 200C and relative humidity of 55%. Obtained values of
drying shrinkage are given in Table 4.

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By the analyses of shrinkage curves the following conclusions could be derived:

 All types of mortars have intensive shrinkage up to the age of 49 days.
 Reference cement mortar has the lowest measured shrinkage value.
 With the increase of the wheat straw ash content, the value of shrinkage of
mortars P10, P20 and P30 increase. Therefore, mortar with wheat straw ash
content 30% has the highest shrinkage value.
 Shrinkage of mortars PS10, PS20 and PS30 is smaller in comparison to mortars
P10, P20 and P30. The influence of different content of wheat straw ash and
soy straw ash in mortars PS10, PS20 and PS30 is no significant, especially up
to 42 days.
Table 4. Drying shrinkage deformations of mortars in mm/m
Mortar type
E P10 P20 P30 PS10 PS20 PS30
Age, days
4 0.167 0.188 0.188 0.146 0.167 0.167 0.135
7 0.281 0.354 0.365 0.365 0.323 0.333 0.302
14 0.354 0.458 0.500 0.510 0.458 0.479 0.469
21 0.458 0.573 0.625 0.688 0.552 0.573 0.563
28 0.500 0.625 0.688 0.771 0.646 0.656 0.646
35 0.500 0.635 0.688 0.792 0.646 0.656 0.646
42 0.573 0.708 0.760 0.854 0.688 0.687 0.667
49 0.698 0.792 0.854 0.948 0.781 0.760 0.750
56 0.698 0.792 0.854 0.948 0.781 0.760 0.750

Change of drying shrinkage deformations during the time is shown in Figure 6.

Figure 6 - Change of drying shrinkage of tested mortar mixtures in the relation of time

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3. CONCLUSION
Based on the performed experimental research and the analysis of obtained results,
the following conclusions can be obtained:
 The incorporation of biomass ash in cement mortar provided compressive
strength comparable to reference concrete, especially at later ages. The mortars
with biomass ash showed a noticeable strength development up to the age of 90
days. The mortars in which 10% and 20% of cement were replaced with wheat
ash and mortar in which 10% of cement was replaced with combination of
wheat and soy ash, gained compressive strength even higher than referent
cement mortar. This strength development is a consequence of the pozzolanic
characteristics of these biomass-ashes.
 All types of mortars containing biomass ash showed higher shrinkage
compared to the referent mortar. With the increase of the wheat straw ash
content, the value of shrinkage increased, while the value of shrinkage
decreased as the total content of combined wheat straw ash and soy straw ash
increased.
 Mortars in which 10% and 20% of cement were replaced with wheat ash or
with combination of wheat and soy ash have negligible decrease in 28-day
compressive strengths (up to 7%) in relation to the referent mortar. It lead to
the conclusion that cement mortar can be produced by using biomass ashes as
substitutes of cement in amounts up to 20% without compromising their
mechanical properties.

ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project "Examination of ashes developed by combustion of biomass and used as
supplementary cementitious materials in cement composites", supported by the
Provincial secretariat for science and technological development, Serbia. This support
is gratefully acknowledged.

REFERENCES
[1] J.R. González-López, J.F. Ramos-Lara, A. Zaldivar-Cadena, L. Chávez-
Guerrero, R.X. Magallanes-Rivera, O. Burciaga-Díaz - Small addition effect of
agave biomass ashes in cement mortars, Fuel Processing Technology 133, p. 35-
42, Mexico, (2015)
[2] Jan R. Pels, Danielle S. de Nie, Jacob H.A. Kiel – Utilization of ashes from
biomass combustion and gasification, 14th European Biomass Conference &
Exhibition, Paris, France, (2005)
[3] Miroslava Radeka, Vladislav Zekić, Dragan Milić, Mirjana Malešev, Vlastimir
Radonjanin – Physical, chemical and pozzolanic properties of biomass fly ashes,
in Zbornik radova „iNDiS 2015 - Planiranje, rojektovanje, građenje i obnova
graditeljstva“, Novi Sad, 2015, pp. 114-126.

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[4] Hasan Biricika, Fevziye AkoÈza, Fikret TuÈrkerb, Ilhan Berktay - Resistance to
magnesium sulfate and sodium sulfate attack of mortars containing wheat straw
ash, Cement and Concrete Research 30, p. 1189-1197, (2000)
[5] Emir Cabrera, María J. Muñoz, Ricardo Martín, Ildefonso Caro, Caridad
Curbelo, Ana B. Díaz - Comparison of industrially viable pretreatments to
enhance soybean straw biodegradability, Bioresource Technology 194, p. 1–6,
(2015).

[245]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Dragan NIKOLIĆ
Snežana MITROVIĆ2
Goran ĆIROVIĆ3

AN INVERSE METHOD TO DETERMINE THE MODULUS OF

ELASTICITY OF CONCRETE

Abstract: In practice, the elastic modulus of concrete used in the analysis and design has been
determined by empirical formula obtained from experimental results. Concrete is a phase material
consisting of cement paste matrix, discrete inclusions of aggregate, and an interfacial transition zone
(ITZ) between the matrix and the inclusions. This paper presents a numerical concrete model, which
adopts a three-phase model and the material was modeled as a composite by finite element with material
discontinuity that proposed to analyze concrete with complex interface in three dimensions. This
formulation is used to solve the inverse problem of determining the elastic properties of the composite.

Кey words: modulus of elasticity, concrete, inverse method

ODREĐIVANJE MODULA ELASTIČNOSTI BETONA PRIMENOM

INVERZNE METODE
Rezime: Pri analizi konstrukcija u praksi, modul elastičnosti betona se usvaja na osnovu empirijskih
izraza dobijenih iz eksperimentalnih rezultata ispitivanja. Beton je višefazni materijal koji se sastoji od
cementne paste, krupnog agregata i tranzitne zone između cementne paste i agregata. U radu je prikazan
numerički model kojim se beton opisuje kao trofazni materijal i koji je analiziran primenom metode
konačnih elemenata kao diskontinualni trodimenzionalni materijal sa tranzitnom zonom između dve faze.
Ovaj model je korišćen pri rešavanju inverznog problema za odeređivanje elastičnih svojstava
kompozitnog materijala.

Ključne reči: modul elastičnosti, beton, inverzna metoda

1
PhD, Visoka građevinsko-geodetska škola, Beograd, Hajduk Stanka 2, nikolic@vggs.rs
2
PhD, Visoka građevinsko-geodetska škola, Beograd, Hajduk Stanka 2, mitrozs@sezampro.rs
3
PhD, Visoka građevinsko-geodetska škola, Beograd, Hajduk Stanka 2, cirovic@sezampro.rs

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1. INTRODUCTION
The modulus of elasticity of concrete should be determined in order to decide on
rates of strain and deformation in structural designs based on elasticity. Concrete may
strain under various loads due to its flexural nature. In other words, strain depends on
the type and size of the structure and loading period. Elastic modulus of concrete is
usually determined with Ø15x30cm cylindrical specimens tested under various load
levels within elastic limits.
Concrete is defined as a three-phased anisotropic brittle material that behaves
differently under various loads. Total deformation of a structural element that has an
elastic property under P load is directly proportional with applied load and size of the
concrete component, but is inversely proportional with cross sectional area of the
element. Concrete is a brittle and a composite material consisting of various phases.
However, it has elastic behavior under low stresses. Theoretically, this is equal to a
value of 30-45 % of its compressive strength. Therefore, concrete is considered as an
elastic material in engineering calculations. The σ−ε diagrams are used for explaining
elastic behavior of concrete determined by experimental methods [8].
Nondestructive techniques, such as the resonant frequency and ultrasound
methods, also can be used to measure modulus of elasticity directly. On the basis of
the experimental results, various empirical formulas are derived for practical use by
engineers [12]. However, the empirical formulas are often too simple to differentiate
the effects of some factors, such as the interfacial transition zone (ITZ) thickness,
aggregate shape, and aggregate gradation, on Young’s modulus of concrete [4].
Therefore, it is still necessary to theoretically investigate the quantitative correlation
between the macroscopic Young’s modulus and mesostructure of concrete.
Many researchers have attempted to estimate the elastic modulus of concrete by
both analytical and numerical methods. In the simplest model for the estimation of
elastic modulus of concrete, the concrete is assumed to be a two-phase material,
which consists of coarse aggregates and mortar matrix. The use of two-phase model
provided reasonable estimation for practical purposes, but did not give insightful
results. The difference between the real value and the estimated value by two-phase
model arose from the fact that the model did not consider interfacial transition zone in
concrete at all. This interfacial transition zone, which deeply affects the
characteristics of concrete such as strength, permeability, and crack, must be
considered in the modeling of concrete to capture more realistic behavior of concrete.
Three-phase model, which assumes that concrete is composed of aggregate, mortar
matrix, and interfacial transition zone, has been introduced for the estimation of
elastic modulus of concrete by other researchers[5–8].
In studies by Hashin et al., Neubauer et al., Ramesh et al., and Garboczi et al.,
interfacial transition zone was modeled as thin shell surrounding aggregate and the
model gave reliable results [3, 8, 10,2]. However, it is difficult to estimate elastic
modulus of concrete practically using the three-phase model, since interfacial

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transition zone is too thin to be modeled precisely by conventional numerical

methods.
This paper presents a numerical concrete model, which adopts a three-phase model
and finite element with material discontinuity, for the estimation of elastic modulus of
concrete.

2. SIMULATION OF THE MESOSTRUCTURE OF CONCRETE

Concrete made with different aggregates, i.e., the elastic modulus of fine aggregate
being different from that of coarse aggregate is considered in this paper. In order to
predict the elastic modulus of the concrete as accurately as possible, detailed
knowledge of the mesostructure of concrete is essential [1]. This can be achieved
through simulating the distribution of aggregates and ITZs in concrete, since the
mesostructure of concrete in practical use is random by nature.
Through random simulation, the heterogeneity of concrete can be represented as
realistically as possible. To facilitate the numerical simulation of elastic modulus,
numerical sample of three-phase concrete material is firstly established. The take-and-
place method is adopted to generate two-dimensional inner geometry of concrete. The
aggregate is represented by angular polygon. The particle size is defined as the
minimum width of circumscribed rectangular, the aspect ratio of which is defined as
its elongation gagg. Numerical model of the mesostructure of concrete is adopted
from literature [14].
According to the adopted particle size distribution and volume ratio, aggregate
particles are taken and then randomly placed into a square matrix from large to small
to realize the random aggregate structure (RAS) of concrete by a carefully designed
Monte-Carlo algorithm. In the simulation below, the Fuller parabola is employed to
describe the particle size distribution of dense graded coarse aggregate particles:
0.5
 D  Dmin 
y    (1)
 Dmax  Dmin 
where y denotes the weight ratio passing a sieve with aperture diameter D, and
Dmax;min are the largest and smallest particle sizes, respectively. The volume ratio
of coarse aggregate fagg is retained as fagg= 0:40, and Dmax =16 mm, Dmin = 4 mm.
The elongation of particles gagg is treated as a random variable observing continuous
uniform distribution, abbreviated as U(a;b) with minimum value a and maximum
value b.
The interfacial transition zone is considered as a soft shell surrounding aggregate.
After the realization of random aggregate structure, a thin layer with certain thickness
is isolated from the interface between aggregate and matrix and identified as ITZ. In
literature, there are many experimental observations on the thickness of ITZ. For
various concrete materials observed by different methods, the thickness of ITZ is also
different but mainly located in the range of 20–100 mm [9,13].

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Since the elastic modulus of concrete sample will be solved by finite element
method, all the three phases are discretized with 6-node triangular element employing
the free mesh function of general finite element analysis package ‘‘Abaqus’’. The
triangular element type adopted here has great adaptation to complex geometry of
three phase concrete material and good mesh quality is ensured. The requirement on
the shape of all elements is satisfied to ensure good accuracy of FEM analysis.
Besides, the mesh size of all triangular elements for the interfacial transition zone is
small enough to estimate the effect of ITZ. For the typical numerical sample of 150
mm square, there are about 250,000 nodes, 120,000 elements after meshing operation,
which takes much of the computing time due to the complex geometry and very fine
mesh around ITZ.

3. ANALYSIS ALGORITHM OF ELASTIC MODULUS

The elastic modulus of heterogeneous concrete composite is solved by average-
field theory, which is often used to determine the effective properties of
heterogeneous material from microscopic scale [5,12]. By defining effective
mechanical properties, average-field theory can give the relation between volume
average strain and stress of microscopically heterogeneous materials. Considering a
volume element V made of heterogeneous material with an external boundary jV, the
volume average stress sij and strain eij can be given as:
1 1
 ij 
VV  ij ( x)dV ;  ij    ij ( x)dV
VV
where x is the position vector. The generalized Hooke’s law for such a volume
element gives
 ij  Cijkl
App
 kl ;  ij  Sijkl
App
 kl
where CAppijkl and SAppijkl denote apparent stiffness tensor and compliance tensor,
respectively.
Through the well-known Average Strain and Stress Theorems, the corresponding
volume average strain eij and stress sij can be computed easily as average integral
on external boundary instead of volume

 u (S )n 
1 1
 ij  
V V
Ti ( S ) x j dS ;  ij 
2V V
i j  u j ( S )ni dS

where S; ni; Ti(S); ui(S) denote volume surface, outward unit normal vector,
boundary traction and boundary displacement field, respectively. If homogeneous
displacement field is applied on volume surface S,
ui (S )   ij0 x j for x  S
where e0ij is a constant strain tensor, then the average strain field will satisfy

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 ij   ij0
If homogeneous traction field is applied on the surface S,
Ti (S )   ij0 n j , for n  S
where s0ij is a constant stress tensor, then the average stress field will satisfy
 ij   ij0
Because the aggregate inclusions in concrete sample are not ideally random-
oriented due to its limited number, the stiffness tensor or compliance tensor of
numerical samples are not perfectly isotropic, although the microstructure generated
by Monte-Carlo method is expected to be. For 2D case, herein only the engineering
modulus E11;22 relating the axial strain and stress is directly solved through applying
loading that only one non-zero average stress or strain component is produced. The
main components of stiffness tensor C11;22 for any sample under homogeneous
displacement boundary condition (HDBC) and main components of compliance
tensor S11;22 under homogeneous traction boundary condition (HTBC) are firstly
solved. Then, the effective elastic modulus of concrete material E is defined as the
average value of engineering modulus E11 and E22,
(C11  C22 )(1  v 2 ) 1 1 1 
E or E    
2 2  S11 S 22 
where m is overall Poisson’s ratio of concrete. Since our goal is to obtain the
elastic property only, all the three phases of concrete are assumed to be isotropic and
perfectly bonded together.
To consider the effect of the interfacial transition zone as an interphase, two
models for composites with coated inclusion deposited into a matrix are adopted.
Based on the generalized self-consistent scheme (GSCS), the four-phase model
suggested by Hashin gives the effective bulk modulus KEff as [3]:
f m  f agg
K Eff  K m 
1 /( K e  K m )  3 f m /(3K m  4Gm )
where
f agg /( f m  f agg )
K e  K ITZ 
1 /( K agg  K ITZ )  [3 f ITZ /( f m  f agg )] /(3K m  4Gm )
In the above two equations, f, K and G stand for the volume ratio, bulk and shear
modulus, and subscript m, agg, ITZ denote matrix, aggregate and interfacial transition
zone, respectively. Another model suggested by Ramesh gives the effective bulk
modulus as [11]
1   2
K eff 
3  4

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where

 1  ( f agg  f ITZ )(3K agg  4GITZ )[ K m (4Gm  3K ITZ )  4( f agg  f ITZ )Gm ( K ITZ  K m )]
 2  4 f agg ( K agg  K ITZ )[3K m (GITZ  Gm )  ( f agg  f ITZ )Gm ( K m  4GITZ )]
 3  ( f agg  f ITZ )(3K agg  4GITZ )[(4Gm  3GITZ )  3( f agg  f ITZ )( K ITZ  K m )]
 4  3 f agg ( K agg  K ITZ )[3(GITZ  Gm )  ( f agg  f ITZ )(3K m  4GITZ )]
The above two theoretical estimate schemes are applied to numerical concrete
material with random aggregate structure, constant volume ratio of aggregate f agg =
0.4 and constant width of ITZ 100mm.

From experimental data available in the literature, it seems that the elastic modulus
mainly locates in the range of 10–35 GPa for general hardened cement pastes with
water to cement ratio about 0.4–0.6 [5,10,12]. From this consideration, the elastic
modulus of matrix is adopted as a constant Em=25 GPa to simplify the analysis. The
elastic modulus of aggregate, interfacial transition zone and concrete are generally
noted in terms of matrix’s elastic modulus. The relative elastic modulus of aggregate,
ITZ and concrete, which are also named as contrast ratio below, are defined as
agg  Eagg / Em , ITZ  EITZ / Em , c  Ec / Em
where subscript c stands for concrete material. Although ITZ can be strengthened
by some methods like adding fine or ultrafine supplementary cementing materials, it
is generally softer than the matrix . Hashin and Monteiro also reported that the
Young’s modulus is about 50% of those of the bulk cement pastes [3]. With the aid of
nanoindentation technique, the relative elastic modulus of ITZ to matrix is measured
to be about 70–90%.λ
2
Rel. elastic modulus of concrete lc [-]

1.8

1.6

1.4 λITZ=0.30
λITZ=0.60
1.2

1
1 2 3 4 5 6 7 8 9 10

Contrast ratio of aggregate lagg [-]

Figure 1 – Impact of contrast ratio of aggregate and ITZ on relative elastic modulus of
concrete

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The numerical results are presented in Fig. 1. The numerical simulation is

performed on only one concrete sample of 150 mm square under HTBC.
It is indicated that the estimate can well reflect the impact of aggregate and ITZ on
elastic modulus from the numerical simulation. In terms of contrast ratio of aggregate
lagg as well as ITZ lITZ, the variation curves of elastic modulus of concrete.

4. CONCLUSIONS
Theoretical models are applied to investigate the impact of ITZ and aggregate on
overall elastic modulus of concrete material. The incorporation of aggregate into
matrix brings two opposite effects. Stiff aggregate will enhance the elastic modulus of
concrete while soft ITZ surrounding aggregate will reduce it.
The mesostructure of concrete has been reproduced by distributing aggregate
particles within a rectangular element and the finite element model has been
employed for the stress analysis in the concrete. On the basis of the numerical results,
the effects of the maximum aggregate diameter, aggregate gradation, ITZ thickness,
and aggregate on Young’s modulus of concrete are evaluated in a quantitative
manner.
Because of the concentric microstructure that ITZ coats all the aggregate
inclusions, stiff ITZ can greatly cancel the enhancement of stiff aggregate on overall
elastic modulus.

ACKNOWLEGMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications" supported by
the Ministry of Education, Science and Technology, Republic of Serbia. This support
is gratefully acknowledged.

REFERENCES
[1] Berryman, J.G., 2006. Measures of microstructure to improve estimates and
bonds on elastic constants and transport coefficients in heterogeneous media.
Mechanics of Materials,38:732-747.
[2] Garboczi, E.J., Bentz, D.P., 1997. Analytical formulas for interfacial transition
zone properties. Advanced Cement Based Materials, 6:99-108.
[3] Hashin, Z., Monteiro, PJM., 2002. An inverse method to determine the elastic
properties of the interphase between the aggregate and the cement paste.Cement
and Concrete Resresearch,32:1291–1300.

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[4] Lee, KM., Park, JH.,2008. A numerical model for elastic modulus of concrete
considering interfacial transition zone. Cement and Concrete Research,38:396–
402.
[5] Li, GQ., Zhao, Y., Pang, SS., Li, YQ.,1999. Effective Young’s modulus
estimation of concrete. Cement and Concrete Research, 29:1455–1462.
[6] Li, G.Q., Zhao, Y., Pang, S.S., 1999. Four-phase sphere modeling of effective
bulk modulus of concrete. Cement and Concrete Research, 29:839-845.
[7] Li, C.Q., Zheng, J.J., Zhou, X.Z., McCarthy, M.J., 2003. A numerical method for
the prediction of elastic modulus of concrete. Magazine of Concrete Research,
55:497-505.
[8] Mehta, PK., 2006. Concrete, Prentice-Hall Inc., USA,
[9] Neubauer, CM.,Jennings, H.M., Garboczi, EJ.,1996. A three-phase model of the
elastic and shrinkage properties ofmortars. Advance Cement Based Matererials,
4:6–20.
[10] Nilsen, AU., Monteiro,PJM.,1993. Concrete: a three phase material. Cement and
Concrete Research. 23:147–151.
[11] Ramesh, C., Sotelino, ED., Chen, WF., 1996. Effect of transition zone on elastic
moduli of concrete materials. Cement and Concrete Research, 26:611–622.
[12] Topcu, IB., Bilir, T., and Boga, AR.,2010. Estimation of the modulus of
elasticity of slag concrete by using composite material models. Construction and
Building Materials, 24:741–748.
[13] Zheng, J.J., Li, C.Q., Zhou, X.Z., 2005. Thickness of interfacial transition zone
and cement content profiles between aggregates. Magazine of Concrete
Research, 57:397-406.
[14] Zhou, C., Li K., Ma, F.,2014. Numerical and statistical analysis of elastic
modulus of concrete as a three-phase heterogeneous composite. Computers and
Structures: 139:33-42.

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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Irena NIKOLIĆ
Dijana ĐUROVIĆ2
Radomir ZEJAK3

STRENGTH AND DURABILITY OF ALKALI ACTIVATED BINDERS

BASED ON FLY ASH AND SLAG
Abstract: This research has provided information about the influence of type of alkaline activator (Na
and K activator) and slag addition on the strength and durability of fly ash based alkali activated binders
(AABs). The results have shown that choice of alkaline activator greatly influences the strength of both,
purely fly ash based AABs and alkali activated fly ash /slag blends. The AABs prepared with K activator
generally reach a higher strength in comparison to Na-AABs while the AABs prepared with Na activator
display the better durability in different aquatic. Moreover, slag addition positively influences the
strength evolution and durability of fly ash based AABs.

Кey words: fly ash, slag, alkali activated binders, strength, durability.
.

ČVRSTOĆA I POSTOJANOST ALKALNO AKTIVIRANIH VEZIVA

NA BAZI PEPELA I ŠLJAKE
Rezime: Ovo istraživanje je obuhvatilo ispitivanje uticaja tipa alkalnog akivatora (Na i K aktivatora i
dodatka šljake na čvrstoću i postojanost alkalno aktiviranih veziva (AAV) na bazi pepela. Rezultati su
pokazali da izbor alklanog aktivatora u velikoj mjeri utiče na čvrstoću i postojanost alkalno aktiviranih
veziva na bazi pepela i na bazi mješavine pepeo/šljaka. Uzorci AAV pripremljeni sa K vezivom
generalno dostižu veću pritisnu čvrstoću dok uzorci AAV pripremljenim sa Na alkalnim aktivatorom
(Na-AAV) pokazuju bolju postojanost u različitim vodenim rastvorima. Osim toga dodatak šljake
pozitivno utiče na čvrstoću i postojanost AAV na bazi pepela.

Ključne reči: pepeo, šljaka, alkalno aktivirana veziva, čvrstoća, postojanost.

1
University of Montenegro, Faculty of Metallurgy and Technology, Podgorica, Montenegro
2
Institute of Public Health of Montenegro, Podgorica, Montenegro
3
University of Montenegro, Faculty of Civil Engineering,Podgorica, Montenegro

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1. INTRODUCTION
Alkali-activated binders are the new generation of building materials which are
considering as alternative to traditional Portland cement binder. Mainly, blast furnace
slag was used as a source material for alkali activation process, but recently the focus
has shifted to slag coming from steel processing [1]. Since the production of AABs is
associated with low energy consumption and low CO2 emission, the use of these
binders has technological and ecological advantages in comparison with Portland
cement binder. Moreover, these materials may reach a very high mechanical strength
and display a better durability in a high temperature conditions and aggressive aquatic
environment in comparison to the cement binder which make them a very interesting
alternative from both scientific and commercial points of view [2].
Alkali activation process involves the chemical reaction of source materials and
alkalis like alkali silicates or hydroxides. The process begins with destruction of the
Ca–O, Si–O–Si, Al–O–Al and Al–O–Si bonds in the source materials during the
dissolution stage, which is followed by polymerization and hardening processes.
Understanding the durability of any building material when exposed to aggressive
environments is critical in predicting how the material will behave in service [3].
Within this context, the current research is aimed to investigate the effect of type of
alkali activator on the strength and durability of AABs prepared using the fly ash and
electric arc furnace steel slag (EAFS).

2. EXPERIMENT
Fly ash (FA) and electric arc furnace steel slag (EAFS) supplied from coal fired
power station and Steel mill in Montenegro were used as a source materials. Their
chemical composition is given in the Table 1.
Table 1- Chemical composition of fly ash and slag
FA EAFS
Component % Component %
SiO2 49.45 CaO 46.5
Fe2O3 5.23 FeO 23.5
Al2O3 21.77 SiO2 12.2
TiO2 0.66 Fe2O3 0.9
CaO 13.34 MgO 6.5
Na2O 0.46 MnO 1.3
ZnO 4.510-3 Cr2O3 0.8
MgO 1.29 Al2O3 7.24
MnO 0.02 TiO2 1.06
P2O5 0.24
K2O 1.4
LOI* 4.35
*
Loss on ignition.

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The purely fly ash and mixture composed from 70 % of FA and 30 % of EAFS
were alkali activated with the Na and K activator at solid to liquid mass ratio of 1.3.
Na - activator was prepared by the mixing of 10 M NaOH and Na2SiO3 (water glass:
Na2O = 8.5%, SiO2 = 28.5%, density of 1.39 g/cm3) solutions in a mass ratio of 1.5,
while K-activator was the mixture of 10 M KOH and K2SiO3 (water glass : K2O
=13.18 %, SiO2 = 26,38 %, density of 1.39 g/cm3) solutions.
The four different samples of AABs were prepared (Table 2). The paste obtained
by alkali activation was casted in a plastic cylindric mould (28 x 60 mm), and cured
for 48h at 65 °C. After this, the samples of AAS were removed from moulds and left
to stay an additional 14 days at ambient temperature before any testing was
performed.
Table 2- Composition of initial solid mixtures
Sample FA (%) EAFS (%) A c t i v a t o r t yp e
Na-F-AAB 100 0 Na-activator
K-F-AAB 100 0 K-activator
Na-F/S-AAB 70 30 Na-activator
K-F/S-AAB 70 30 K-activator

For the purpose of the durability test, the AAB samples were immersed in distilled
water, sea water, simulated acid rain (H2SO4:HNO3 60:40 wt.%, pH 3) and 1M HCl
over the period of 14 weeks. The pH values of solutions were monitored weekly.
Compressive strength of samples was recorded before and after the durability tests.

3. RESULTS AND DISSCUSION

The results of investigations have shown that the strength of AAB is strongly
dependent on the type of alkaline activator and composition of initial solid mixture
(Figure 1). Generally, AABs synthesized using the K activator display the higher
compressive strength in comparison to those synthesized using Na activator.
The higher strength of purely fly ash based alkali activated binders prepared with
K activator (K-F-AAB) is attributed to the higher degree of polymerization in a
system containing K ion, compared to those containing Na cations [4] due to the
difference of alkali cation sizes. Smaller Na cations bind strongly with silicate species
present in the alkali solution so that the pair is relatively inert to condensation with
another silicate species [5] which results in a lower degree of polymerization and
lower compressive strength of the Na-F-AAB compared to the strength of K-F-AAB.

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Figure 1 – Influence of composition of alkali activator and initial solid mixture on the strength
of AABs

Besides, the fly ash substitution with the slag positively affect the strength
evolution of fly ash based AABs. The results of mechanical investigations indicated
that steel slag addition in amount of 30 % by weight to fly ash promotes the strength
development of fly ash based AABs. The strength of Na-F/S-AAB and K-F/S-AAB
samples is higher then the strength of purely fly ash based alkali activated binders
(Na-F-AAB and K-F-AAB). Moreover, K-F/S-AAB sample reached the higher
strength in comparison to the Na-F/S-AAB. The glassy (amorphous) phases of slag is
more vulnerable to alkaline attack than the aluminosilicates enriched ones from fly
ash under room temperature and the slag generally has a higher content of reactive
phase than fly ash, thus a higher amount of hydrated reaction product will be formed,
which can explain the increase in compressive strength by the slag addition [6].
The durability testes have shown that immersing of AABs in distilled water and
acid rain, immediately boosts the pH of the highly alkaline solution to about 11, due
to the mobility of alkali cations in solution. While in contact with an aquatic
environment, ion exchange between Na+ or K+ and H3O+ occurs, contributing to the
increase of pH [7]. The pH values of sea water and 1M HCl solution after the
immersion of ABBs were about 8.6 and 2.4, respectively. The pH values of solutions
were monitored weekly and there were no significant changes.
Durability of purely fly ash based AABs is also strongly influenced by the type of
alkaline activator, while the slag addition reduces this effect (Figure 2). It is evident
that the purely fly ash based AABs loose the strength (about 30 - 44 %) after the
exposure to the attack of aggressive aquatic environment. That strength loss was
higher in a case when K- activator was used for preparation of AABs. Slag addition to
the fly ash in amount of 30 % greatly improves the durability of fly ash based alkali

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activated binders. The strength loose of Na-F/S-AAB and K-F/S-AAB samples after
the attack of distilled water, sea water and acid rain was up to 23 %.
In addition, the purely fly ash based alkali activated binders (Na-F-AAB and K-F-
AAB) which were immersed in a 1 M HCl solution have shown the dramatic
deterioration thus these samples were not tested for compressive strength. On the
other hand, samples prepared with the addition of 30 % of slag displayed the residual
strength after immersion in 1M HCl.

Figure 2 – Influence of composition of alkali activator and initial solid mixture on the strength
of AABs

4. CONCLUSIONS
The durability of alkali activated binders synthesized using the fly ash and fly ash
slag/blends with the two types of alkaline activators were investigated. The results
have shown that the choice of alkaline activator greatly influences the both,
mechanical properties and durability of AABs. Generally, AABs prepared with K
activator display the better mechanical properties than their Na counterpart but they
are characterized by lower durability in different aquatic environment. Addition of
slag has improved the booth, compressive strength and durability of fly ash based
alkali activated binders.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the financial support of the Montenegrin
Ministry of Science in the framework of Project No. 01-460.

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REFERENCES
[1] Salmana, M., Cizer, Ö., Pontikes,Y., Vandewalle, L., Blanpain, B., Van Balen,
K., 2014, Effect of curing temperatures on the alkali activation of crystalline
continuous casting stainless steel slag, Construction and Building Materials 71,
308–316.
[2] Van Deventer, J.S.J., Provis, J.L., Duxson, P., Brice, D.G., 2010, Chemical
research and climate change as drivers in the commercial adoption of alkali
activated materials, Waste Biomass Valoriz 1, 145–155.
[3] Bernal, S. A., de Gutiérrez, R. M., Pedraza, A. L., Provis, J.L., Rodriguez, E.D.,
Delvasto ,S., 2011, Effect of binder content on the performance of alkali-
activated slag concretes, Cement and Concrete Research 41, 1–8
[4] Xu, H., van Deventer, J.S.J., 2003, The effect of alkali metals on the formation
of geopolymeric gels from alkali-feldspars, Colloids and Surfaces A:
Physicochem. Eng. Aspects 216, 27 -/44.
[5] McCormick, A.V., Bell, A.T., Radke, C.J., 1989, Influence of Alkali-Metal
Cations on Silicon Exchange and Silicon-29 Spin Relaxation in Alkaline Silicate
Solutions, J. Phys. Chem. 93, 1737-1741.
[6] Chithiraputhiran, S.,Neithalath, N., 2013, Isothermal reaction kinetics and
temperature dependence of alkali activation of slag, fly ash and their blends,
Construction and Building Materials 45, 233–242.
[7] Aly, Z., Vance, E.R., Perera, D.S., Hanna, J.V., Griffith, C.S., Davis, J., Durce,
D., 2008, Aqueous leachability of metakaolin-based geopolymers with molar
ratios of Si/Al = 1.5–4, Journal of Nuclear Materials 378, 172–179.

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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Miroslava RADEKA
Tiana MILOVIĆ2
Mirjana MALEŠEV3
Vlastimir RADONJANIN4

EFFECT OF ZEOLITE ON BASIC PHYSICAL PROPERTIES,

MECHANICAL PROPERTIES AND FROST RESISTANCE OF
CEMENT MORTARS
Abstract: Different properties of natural zeolite as supplementary cementitius material in cement pastes
and mortars are presented in this paper. They contain 0%, 10%, 20% and 30% of natural zeolite in
relation to cement mass. The products of hydration in pastes at 28 days determined by XRD and textural
properties (low temperature nitrogen) of mortars do not correlate to the mechanical properties of mortars
at 28. 60, 90 and 180 days. Compressive strength of these mortars has increased over time and at 180
days mortar with 10% natural zeolite exceeded the standard cement mortar strength value. Furthermore,
natural zeolite in all samples has positively influenced the shrinkage while the best results in frost
resistance of mortars have been obtained in the samples with 10% of natural zeolite.

Кey words: natural zeolite, hydration products, compressive strength, shrinkage, frost resistance.

UTICAJ ZEOLITA NA OSNOVNA FIZIČKA SVOJSTVA,

MEHANIČKA SVOJSTVA I OTPORNOST NA MRAZ CEMENTNIH
MALTERA
Rezime: U ovom radu su predstavljeni razliĉiti rezultati dobijeni na pastama i malterima gde je cement
delimiĉno zamenjen prirodnim zeolitom. U oba sluĉaja cement je zamenjen sa 0%, 10%, 20% i 30%
prirodnog zeolita u odnosu na masu cementa. Produkti hidratacije odreĊeni XRD analizom na pastama za
starost od 28 dana i vrednosti teksturalnih svojstava (Niskotemperaturna adsorpcija azota) maltera nisu u
korelaciji sa mehaniĉkim svojstvima maltera starosti 28, 60, 90 i 180 dana. Ĉvrstoća na pritisak ovih
maltera je rasla sa vremenom i za starost od 180 dana, malter sa 10% prirodnog zeolita je dostigao
ĉvrstoću veću od standardnog maltera. Osim toga, prirodan zeolit pozitivno utiĉe na skupljanje svih
uzoraka, a najveća otpornost na mraz je dobijenja za uzorake sa 10% zeolita.

Ključne reči: prirodan zeolit, produkti hidratacije, ĉvrstoća na pritisak, skupljanje i otpornost na mraz.

1
Professor, University of Novi Sad, Faculty of Technical Sciences, mirka@uns.ac.rs
2
Research Assistant, University of Novi Sad, Faculty of Technical Sciences, tiana.tatomirovic@gmail.com
3
Professor, University of Novi Sad, Faculty of Technical Sciences, miram@uns.ac.rs
4
Professor, University of Novi Sad, Faculty of Technical Sciences, radonv@uns.ac.rs

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1. INTRODUCTION
The group of supplementary cementitious materials (SCMs) comprises materials
that show either hydraulic or pozzolanic behavior. Zeolite belongs to the group of
natural SCMs with pozzolanic activity. The pozzolanic activity is by convention
described as a measure for the degree of reaction over time between pozzolan and
Ca2+ or Ca(OH)2 in the presence of water.
Many studies have advocated the use of natural zeolites as a pozzolan like
supplementary cementitious material, based on their positive effect on the
performance as in preventing bleeding, segregation and delamination of fresh
concrete, decrease of permeability of hardened concrete. It also enhances durability
[1], especially alkali-aggregate reaction and it minimizes the cracks caused by self-
shrinkage in high performance concrete [2]. The most widespread siliceous zeolite in
Serbia is clinoptilolite. One of the silica rich zeolites, like clinoptilolite have been
found to render the cement with SCMs better performances in terms of strength and
durability than aluminous zeolites. The principal factors that have been suggested to
control the zeolite reactivity can be: elevated cation-exchange capacity, Si/Al ratio of
the zeolite framework, instability of the low-density microporous crystal structure
with respect to the structures of higher density, such as feldspars or quartz and the
high densities of defects in zeolite crystals [3].
The influence of pozzolans on the early and final strength of mortar/concrete is not
straightforward [1]. It has been conceived that development of strength is controlled
by dilution effect, the filler effect, the hydration acceleration effect and the pozzolanic
reaction. The rate of the pozzolanic and hydraulic reactions principally determines the
moment when the strength of cement with SCMs exceeds the strength of portland
cement. It is necessary to point out that hydrated portland cement only contains about
20% of Ca(OH)2. The lack of this compound would impede pozzolanic reaction if the
amount of pozzolan was over 40%.
Besides pozzolanic reaction, the properties of hardened mortar/concrete depend on
the developed microstructure, i.e. on the distribution, type, shape of both reaction
products and pores. The pore structure is one of the most important factors governing
the durability, such as drying shrinkage and frost resistance [4].

2. MATERIALS AND METHODS

2.1. Materials
Natural zeolite (particle diameter less than 120 m) from the quarry from Igros
(Brus, Serbia) and Portland cement, CEM I 42.5 (Lafarge, Beocin, Serbia), have been
used in this study.
Two kinds of samples have been prepared: natural zeolite, as SCM, has been
added in cement pastes and mortars. Both kinds of samples have been prepared with
binders comprising natural zeolite with 0%, 10%, 20% and 30% of cement by mass
(samples C, CZ10, CZ20 and CZ30 respectively). Water-to-binder ratio (W/B =0.5)

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has been retained for all samples. Superplasticizer has been added for mortar samples
only. The curing procedure of mortar samples has followed the procedure provided in
standard SRPS EN 196-1.
The dimensions of paste samples were 1x1x6 cm. Paste samples have been used
for determination of mineralogical (XRD) properties, while mortar samples have been
used for determination of textural, mechanical and frost resistance properties.
Mineralogical, textural and mechanical properties have been followed over time (28,
60, 90 and 180 days). The examination of mineralogical properties over time is still
not finished.
2.2. Methods
2.2.1. Chemical analysis
The chemical composition of natural zeolite has been determined in accordance
with SRPS EN 196-2. The results are given in Table 1. The ion exchanged capacity
has been determined using NH4+ ion. The NH4+ capacity of the zeolite is based on its
ability to exchange Ca++,, Na+ and K+ cations by NH4+ ion.
2.2.2. X-ray powder diffraction
The XRD patterns have been acquired on Philips X-ray powder diffractometer
type PW-1710 using copper anticathode with CuKα=1.54128Ǻ and graphite
monochromator. Powder XRD analysis has been performed in the 2θ(º) angle range
from 5° to 50° with a 0.02° step in experiments. The identification of the existing
mineral phases has been performed by comparing interpolate distances (d) and
relative intensity (I) with literature data, or the appropriate card from the JCPDS files.
The qualitative phase analysis of natural zeolite has been published in paper [5]
while the results of hydration after 28 days are presented in this paper.
2.2.3. Textural properties
Low temperature nitrogen adsorption (LTNA), Model 2000, (ASAP Micrometrics,
USA) has been used for determination of textural properties (specific surface area,
pore volume and average pore diameter). Powder samples (natural zeolite - Z,
ordinary Portland cement - CEM I) have been oven-dried at 100oC while mortar
samples (C, CZ10, CZ20, CZ30, 28, 60, 90 and 180 days old) have been oven-dried
and degassed at 50oC. At this temperature the structure of C-S-H, ettringite and other
hydration products should remain stable, while the pore structure could be coarsened
and micro-cracks could appear due to generation of thermo-hydric stresses.
2.2.4. Compressive strength
Mechanical performance of the mortars has been estimated by measuring the
compressive strength of samples at different age, as mentioned in section 2.1, in
accordance with standard SRPS EN196-1. Hydraulic press with a range of 150 kN
has been used.

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2.2.5. Drying shrinkage

Drying shrinkage deformations of all mortar samples have been determined in
accordance with the method described in SRPS B.C8.029. Measurements were started
at the age of 3 days of each mortar, and were conducted after 4, 7, 14, 28, 35, 42 and
49 days. For measuring of length differences of mortar samples, length comparator
with base of 160mm has been used. The samples have been cured in climatic chamber
at the temperature of 200C and relative humidity of 70%.
2.2.6. Frost resistance
Frost resistance of mortar samples has been estimated in accordance with JUS
U.M1.016. The total of six samples of each mortar batch including the referent
mortar, have been prepared (3 samples were exposed to the frost, whereas 3 samples
were referent ones). After 28 days of standard treatment procedure, 3 samples of each
mortar were saturated with water through the method of gradual submersion under
standard atmospheric conditions. Afterwards, each sample was exposed to 50 cycles.
Each cycle lasted for 8h and it consisted of 4h of freezing at -20 ±2o C and 4h of
submerging in tap water.
After 50 cycles, compressive strength of samples has been measured and the
results are presented in Table 7.

3. RESULTS AND DISCUSSION

3.1. Chemical analysis
The stability of zeolite structure depends on several factors. One of them is ratio
Si/Al. In this case the value of this ratio is 4.95, Table 1. The smaller the ratio, the
greater the extent of isomorphous substitution of Al for Si in the tetrahedral
framework.

Table 1- Chemical composition of natural zeolite

Chemical composition of natural zeolite from Igros [%]
SiO2 Al2O3 FeO Fe2O3 CaO MgO TiO2 Na2O K2O P2O5 L.I.* L.H.** SO3
62.30 12.59 0.23 1.20 4.80 1.94 0.22 0.70 0.63 0.016 11.06 4.59 0.05
* Loss on ignition
** Loss by heating

The cation-exchange capacity is the sum of the exchangeable cations that can be
bonded by mineral framework, at a certain pH, Table 2.

Table 2- Exchanged ion capacity and exchanged cations after treatment with NH4+
CEC ( meq/100g) K Na Ca Mg
180 4.4 7.3 147.5 20.8

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The major exchangeable cation in the investigated natural zeolite is Ca ++. Such
high concentration of Ca++.bonded to the structure of natural zeolite has slowed down
the entrance of these ions from Ca(OH)2 solution formed during the process of
cement hydration, i.e. pozzolanic reaction.
3.2. Mineralogical characterisation
After 28 days, XRD analyses have been carried out in order to compare the
products of hydration obtained in pastes composed of pure cement and cements with
natural zeolite as SCMs.
The main mineral component of natural zeolite is clinoptilolite [5]. Aside from
clinoptilolite, a considerable amount of clay mineral smectite is present.
These results are presented in Fig.1.

Figure 1– XRD patterns of cement and cement with natural zeolite as SCMs pastes after 28
days of hydration (P-portlandite, Et-etringite, CSH-calcium silicate hydrate, CAH-calcium
aluminium hydrate)

The main components in all samples (C, CZ10, CZ20 and CZ30) are portlandite,
ettringite, CAH and CSH compounds.
As seen from Fig. 1, the peaks corresponding to portlandite (calcium hydroxide-
CH) have been observed at the lowest intensities of CZ30 samples. The characteristic
peaks of clinoptilolite, the main component of zeolite, have not disappeared.
Moreover, the intensities of the peaks corresponding to clinoptilolite are a bit more
pronounced for CZ30 sample than for others (CZ10 and CZ20). Decrease in the
intensity of Ca(OH)2 peaks in CZ30 sample would normally indicate that pozzolanic
reaction in this sample is more prominent. However, the fact that the presence of
clinoptilolite is also significant implies that pozzolanic reaction is not the only reason
for reduction in intensity of these peaks.

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3.3. Textural properties

Low temperature nitrogen adsorption has been used to characterize specific
surface area, volume of pores and average pore diameter of mainly capillary pores.
Pores in cement paste matrix include gel, capillary and hollow-shell pores as well as
air voids. C-S-H gel is the main component of hydrated cement paste and it contains
gel pores. Gel porosity has a major influence on hydration rates. According to Powers
model [2] their size is about 18 nm.
Capillary pores are forming in the space that has been originally occupied by
mixture of cement and water. Their diameters, in well hydrated pastes, mostly range
from 10 nm to 50 nm. The capillary pores with diameters in this range will influence
drying shrinkage and creep, while pores, with diameters greater than 50 nm, will
influence the strength and impermeable characteristics of mortar and concrete [4].
The results of LTNA are presented in Table 3 and in Fig 2, while changes of pore
volume in range 10-50 nm are shown in Table 4.
In general, the average density of anhydrous binder is higher than the one of
hydration products. Therefore, the specific surface area of hydration products is
usually higher than the specific surface area of anhidrous binder. It would be expected
for the progress in hydration process to reduce specific surface area.
Table 3- Specific surface area, pore volume, average pore diameter of CEM I and zeolite
powder as well as mortar samples after 28, 60, 90 and 180 days of hydration
BET
BET surface Avg. pore Pore Avg. pore
Pore volume surface
Samples area 3 diameter Samples volume diameter
m /g area
m2/g nm 2 m3/g nm
m /g
CEM I nat. zeolite
1.5474 0.008483 20.3093 78.1586 0.230315 12.0790
(powder) (powder)
C 28 3.7229 0.027122 14.5287 C 60 5.3361 0.028052 13.0626
CZ10 28 2.6869 0.015946 17.1915 CZ10 60 5.7025 0.028702 11.3592
CZ20 28 7.1364 0.032364 10.1246 CZ20 60 8.4808 0.033095 7.8563
CZ30 28 6.8596 0.032832 11.0274 CZ30 60 7.8057 0.034648 9.1477
C 90 3.7026 0.024635 10.4878 C 180 6.373 0.031882 11.1050
CZ10 90 6.1007 0.030396 10.6400 CZ10 180 6.4808 0.027007 8.868
CZ20 90 6.6467 0.033407 9.0625 CZ20 180 6.8733 0.027998 8.2488
CZ30 90 1.2145 0.025215 10.6963 CZ30 180 10.0106 0.037485 7.4854

Table 4. Volume of pores in the range of 10-50 nm

Pore volume Pore volume
Samples Samples
m3/g m3/g
C 28 0.017735 C 60 0.019153
CZ10 28 0.011006 CZ10 60 0.015927
CZ20 28 0.015837 CZ20 60 0.015058
CZ30 28 0.017046 CZ30 60 0.018823

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However, the increase in pore volume during hydration process increased specific
surface area, as shown in Table 3. These opposite processes have been confirmed for
the estimated samples. For instance, the values of specific surface area for 60 day old
samples have been increased in comparison to 28 day old samples. For 90 day old
samples C and CZ30, these values have decreased very much in comparison to the
values achieved after 60 days of hydration. From 90 to 180 days the values have
increased again.
The breakpoint at which the trend of the increase of pore volume has changed is
90 days, for samples C and CZ30, while for the others it is 180 days.
The average pore diameter decreases for samples C and CZ10 for all ages, while
for samples CZ20 and CZ30 the breakpoint is reached for 90 days old samples.
In terms of pore size distribution, Fig. 2, it is of interest to discuss three ranges of
pore sizes: number of pores up to 3 nm, from 10 to 50 nm and greater than 50 nm. In
general, number of pores up to 3nm has been the highest for samples CZ20 and CZ30
and the lowest for samples denoted as C. It is probable that zeolite structure in these
mortar samples (CZ20 and CZ30) has been continuously decomposed due to reaction
0,12 0,12
C 60 CZ1060
C 90 0,10
CZ1090
0,10
C 180 CZ10180
Pore Volume (cm /g)
Pore Volume (cm /g)

0,08 0,08
3
3

0,06
0,06

0,04
0,04

0,02
0,02

0,00

1 10 100 10 100
Pore diameter, nm
Pore Diameter (nm)
0,13
0,12 CZ20 60 CZ30 60
0,12
CZ20 90 CZ30 90
0,11
0,10
CZ20 180 CZ30 180
0,10
Pore Volume, (cm /g)
Pore Volume (cm /g)

0,09
3

0,08
3

0,08
0,07
0,06 0,06
0,05
0,04 0,04
0,03
0,02 0,02
0,01
0,00 0,00
-0,01
1 10 100 1 10

Pore Dimeter (nm) Pore Diameter (nm)

Figure 2– Pore size distribution in mortars C, CZ10, CZ20, CZ30

with OH¯ ions as a result of the pozzolanic reaction. Number of pores in the range of
10-50 nm decreases in the following order C 28→CZ30 28→CZ20 28→CZ10 28 and
C 60→CZ30 60→CZ10 60→CZ20 60, Table 4.

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3.4. Mechanical properties

The results of testing and analysis of compressive strength and flexural strength
for ages up to 60 days were presented in paper Malešev et al [6]. The results of testing
and analysis of compressive strength for ages up to 180 days are presented in this
paper.
3.4.1. Compressive strength
The average compressive strengths of tested mortars at the age of 2, 7, 28, 60, 90
and 180 days are shown in Table 5.

Table 5- Compressive strength of tested mortar types

Mortar type C CZ10 CZ20 CZ30
Zeolite - 0.1mc* 0.2mc 0.3mc
fcm,2 [MPa] 26.35 19.69 15.94 10.42
fcm,7 [MPa] 38.28 32.34 25.73 19.27
fcm,28 [MPa] 48.28 46.15 42.97 36.25
fcm,60 [MPa] 52.29 50.83 46.88 38.85
fcm,90 [MPa] 52.29 50.94 53.49 42.50
fcm,180 [MPa] 53.23 57.60 52.19 47.71
* mc- mass of cement

The change of compressive strength of different mortar types over time is shown
in Figure 3. It can be concluded that with the increase of zeolite content, the
compressive strength of mortar samples has been respectively reduced in the first 60
days compared to the strength of reference mortar. After 90 days, mortar CZ20 has
reached the strength of the reference mortar, however, after 180 days it went into a
slight decline. The compressive strength of mortar CZ10 exceeded the value of the
reference mortar after 180 days.
Based on the form of diagram "compressive strength - age of mortar", it can be
assumed that the zeolite in the amount of 30% (by cement mass) has had a very small
contribution to the compressive strength compared to the reference mortar.

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mortar compressive strength [MPa] 70

60

50

40 C
30 CZ10
CZ20
20
CZ30
10

0
0 30 60 90 120 150 180
Age [daysi]

Figure 3– Mortar compressive strength vs age

Increasing/decreasing the strength has been further analysed in relation to the

corresponding strength of the reference mortar (Fig. 4). It can be observed that the
differences between the strengths of mortars containing zeolite and their
corresponding referent mortars have been greater at early ages.
120
Change in strength relative to
corresponding ref. value [%]

100

80 180 days
90 days
60
60 days
40 28 days
7 days
20
2 days
0
0 5 10 15 20 25 30
zeolite content [% of cement mass]

Figure 4– Compressive strength in relation to the corresponding strength of reference

mortar [%]

Table 6 shows the strength values expressed as relative percentages of the 28-day
compressive strength of the reference mortar. When compared to the reference value,

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mortar CZ10 at the age of 180 days has had the highest strength development
(19.30%).
Table 6- Compressive strength of tested mortars compared to the 28-day strength
of reference mortar [%]
Mortar type C CZ10 CZ20 CZ30
fcm,2 [%] 54.58 40.78 33.02 21.58
fcm,7 [%] 79.29 66.98 53.29 39.91
fcm,28 [%] 100.00 95.59 89.00 75.08
fcm,60 [%] 108.31 105.28 97.10 80.47
fcm,90 [%] 108.31 105.51 110.79 88.03
fcm,180 [%] 110.25 119.30 108.10 98.82

It is also interesting to mention that mortars C and CZ10 between the ages of 60
and 90 days have not shown any significant strength development.
3.4.2. Drying shrinkage
Calculated values of drying shrinkage are shown in Table 7 [6].

Table 7- Drying shrinkage deformations of mortars [mm/m] [6]

Age [days] 3 4 7 14 21 28 35 42 49
C 0.000 0.083 0.208 0.354 0.448 0.490 0.542 0.646 0.677
CZ10 0.000 0.081 0.185 0.373 0.446 0.446 0.487 0.560 0.560
CZ20 0.000 0.060 0.206 0.415 0.467 0.486 0.498 0.498 0.498
CZ30 0.000 0.060 0.290 0.498 0.560 0.560 0.581 0.581 0.581

The changes of drying shrinkage deformations over time are presented in Figure 5.
Based on the analyses of shrinkage curves the following conclusions could be
derived:
 reference cement mortar has the highest measured shrinkage value;
 the shrinkage of C and CZ10 mortars will continue to increase over time and the
shape of their curves is similar;
 Shrinkage of mortars CZ20 and CZ30 has a different trend in comparison to
mortars C and CZ10. Up to the age of 14 days, CZ20 and CZ30 have intensive
shrinkage. The shape of shrinkage curves of mortars with higher zeolite content
(CZ20 and CZ30) shows convergation to final shrinkage value.

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Figure 5– Change of drying shrinkage deformations over time [6]

Order of decrease of the values of drying shrinkage for 28 and 49 day old samples
has been compared to the sequence in decrease of volume of pores in the range 10-50
nm for 28 and 60 day old samples. Very good correlation has been obtained for
drying shrinkage of 49 day old samples and volume of pores for 60 day old samples.
Good correlation has been obtained for 28 day old samples.
3.5. Frost resistance
After 50 freezing and thawing cycles, the compressive strength of the samples was
tested and the results are shown in Table 8 and Figure 6.

Table 8- Results of frost resistance examination of mortar after 50 freeze-thaw cycles

fcm,et fcm fcm/fcm,et (fcm,et-fcm)/ fcm,et Requirement
Mortar type
[MPa] [MPa] [%] [%] “< 25%”
C 52.29 47.19 90.25 9.75 +
CZ10 50.83 48.23 94.88 5.12 +
CZ20 46.88 30.21 64.44 35.56 -
CZ30 38.85 27.29 70.24 29.76 -

Mortars CZ20 and CZ30 have not met the requirement of permitted decreasing
strength (<25%). while mortar CZ10 has shown the highest frost resistance (Fig. 6).

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Figure 6– Compressive strength in relation to corresponding strength of referent mortar after

exposure to 50 freeze-thaw cycles [%]

4. CONCLUSION
The results obtained in this study for paste and mortar samples with binders
comprising natural zeolite from Igros, Serbia with 0%, 10%, 20% and 30% of cement
by mass (samples C, CZ10, CZ20 and CZ30 respectively) allow for the following
conclusions:
 the main components in all samples (C, CZ10, CZ20 and CZ30) are portlandite,
ettringite, CAH and CSH compounds. Significant decrease in the intensity of
Ca(OH)2 peaks in CZ30 sample does not indicate that pozzolanic reaction in this
sample is more prominent.
 the results of Low Temperature Nitrogen Adsorption generally indicate an
increase of specific surface area over time and a decrease of average pore
diameter. At some ages this trend changes probably due to entering of hydration
products into the channels of clinoptilolite structure. The number of pores of up
to 3nm is the highest for samples CZ20 and CZ30 and the lowest for samples
denoted as C. The number of pores in the range of 10-50 nm, the presence of
which influences the shrinkage, decreases in the following order C 28→CZ30
28→CZ20 28→CZ10 28 and C 60→CZ30 60→CZ10 60→CZ20 60.
 zeolite has a positive effect on shrinkage and helps in reduction of shrinkage.
The reference cement mortar has the highest measured shrinkage value.
Shrinkage curves of mortars C and CZ10 have a similar shape and the shrinkage
of these mortars will continue to increase over measuring period. Shrinkage of
mortars CZ20 and CZ30 has a different trend in comparison to mortars C and
CZ10. Up to the age of 14 days, CZ20 and CZ30 have intensive shrinkage. The
shape of shrinkage curves of mortars with higher zeolite content (CZ20 and
CZ30) shows convergation to final shrinkage value. Very good correlation has

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been obtained for drying shrinkage of 49 days old samples and volume of pores
for 60 day old samples. Good correlation has been obtained for 28 days old
samples.
 Application of zeolite affects the reduction of the mechanical characteristics
related to the early strength of mortars. At the age of 180 days the value of
compressive strength for sample CZ10 exceeded the value of referent sample,
while the obtained value for the sample CZ20 was very close to the referent one.
 Mortars CZ20 and CZ30 have not met the requirement of permitted decreasing
strength (<25%), while mortar CZ10 has shown the highest frost resistance
value.

ACKNOWLEDGEMENTS
The research work reported in this paper is a part of the investigation within the
research project TR 36017 "Utilization of by-products and recycled waste materials in
concrete composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry of Education, Science and Technological Development of the Republic
of Serbia. This support is gratefully acknowledged.

REFERENCES
[1] Mertens G.,Snellings R., Van Balen K., Bicer-Simsir B., Verlooy P., Elsen J.
(2009) Pozzolanic reactions of common natural zeolites with lime and
parameters affecting their reactivity, Cement and Concrete Research 39, pp 233-
240.
[2] Feng N-Q, Peng G-F, (2005). Applications of natural zeolite to construction and
building materials in China, Constr Build Mater 19, pp 579-584.
[3] Kocak Y., Tasci E., Kaya U. (2013) The effect of using natural zeolite on the
properties and hydration characteristics of blended cements, Constr Build Mater
47, pp 720-727.
[4] Mehta K., Monteiro P. (2006). Concrete: Microstructure, Properties and
Materials, 3rd edition, Mc Graw-Hill.
[5] Radeka M., Malešev M., Radonjanin V., Tatomirović T. (2014). Pozzolanic
activity of natural zeolite from one serbian deposit, in International symposium
on researching and application of contemporary achivements in civil engineering
in the field of materials and structures: Proceedings, XXVI Congress, DIMK,
Vrnjaĉka Banja, pp 191-201.
[6] Malešev M., Radonjanin V., Radeka M., Tatomirović T., Lukić I., Bulatović V.
(2014). Zeolite impact on basic physical and mechanical properties of cement
mortars, in International symposium on researching and application of
contemporary achivements in civil engineering in the field of materials and
structures: Proceedings, XXVI Congress, DIMK, Vrnjaĉka Banja, pp 225-236.

[272]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Nenad RISTIĆ
Zoran GRDIĆ2
Gordana TOPLIĈIĆ-ĆURĈIĆ3
Dušan GRDIĆ4

IMPACT RESISTANCE OF CONCRETE MADE WITH ADDITION

MICRO FIBERS AND RECYCLED GRANULATED RUBBER
Abstract: Impact resistance of concrete represents the quantity of absorbed energy which characterizes
its ability to resist failure due to dynamic loads. The paper presents the effects of adding micro-fiber
(polypropylene and steel) and granulated recycled rubber to concrete on its performances in the hardened
state and on its impact resistance. For the testing purposes, six batches of concrete were made. The
testing results demonstrated that the addition of polypropylene and steel fibers to a considerable extent
contributed to increase of the impact resistance of concrete, while the addition of recycled granulated
rubber contributed to increase of the capacity of concrete to absorb energy of impact loads before the
onset of first cracks.

Кey words: impact resistance, concrete, recycled granulated rubber, polypropylene fibers, steel fibers

UDARNA OTPORNOST BETONA SPRAVLJENOG SA DODATKOM

MIKROVLAKANA I RECIKLIRANE GRANULISANE GUME
Rezime: Udarna otpornost betona predstavlja koliĉinu apsorbovane energije kojom se karakteriše
njegova sposobnost da se odupre lomu usled delovanja dinamiĉkog opterećenja. U radu je prikazan uticaj
dodavanja mikrovlakana (polipropilenskih i ĉeliĉnih) i granulisane reciklirane gume betonu na njegove
performance u svežem i oĉvrslom stanju, kao i na njegovu udarnu otpornost. Za potrebe istraživanja
napravljeno je ukupno šest serija betona. Rezultati ispitivanja su pokazali da je dodatak polipropilenskih
i ĉeliĉnih vlakna u znaĉajnoj meri doprineo povećanju udarne otpornosti betona, dok je dodatak
reciklirane granulisane gume doprineo povećanju sposobnosti apsorbcije energije betona usled udarnog
opterećenja pre pojave prve prsline.

Ključne reči: udarna otpornost, beton, reciklirana granulisana guma, polipropilenska vlakna, ĉeliĉna
vlakna.

1
Assist. Ph.D., University of Nis, Faculty of Civil Engineering and Architecture, Serbia, nenad.ristic@gaf.ni.ac.rs
2
Prof. Ph.D., University of Nis, Faculty of Civil Engineering and Architecture, Serbia, zoran.grdic@gaf.ni.ac.rs
3
Ass. Prof. Ph.D., University of Nis, Faculty of Civil Engineering and Architecture, Serbia ,
gordana.toplicic.curcic@gaf.ni.ac.rs
4
Assist. M.Sc., University of Nis, Faculty of Civil Engineering and Architecture, Serbia, dusan.grdic@gaf.ni.ac.rs

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1. INTRODUCTION
Concrete is brittle material, where the degree of brittleness increases as its strength
increases. It is generally accepted that the ductility of concrete can be improved by
adding various types of fibers to the cement mixtures. Adding fibers to concrete
increases its ductility, tensile strength, flexural strength and resistance against
dynamic and impact loads [1-2]. Steel and polypropylene fibers are the most used
fibers.
There are several test methods that evaluate the impact strength of fiber reinforced
concrete where the simplest method is the drop-weight test proposed by the ACI
committee 544. Experimental results from concrete specimens containing 0.1% - 2%
polypropylene fibers showed that the impact strength of concrete increased both for
the first crack and final fracture compared with plain concrete [3]. Marar et al. [2]
showed that for FRCs containing 0.5%, 1%, 1.5% and 2% hooked-end steel fibers
with aspect ratios of 60, 75 and 83, the samples with a higher fiber content (in all of
aspect ratios) had a higher impact strength; also for specimens with 2% fiber content
and aspect ratios equal of 60, 75 and 83, the absorbed energies increased by 38, 55
and 74 times, respectively. Using a drop hammer apparatus, Nataraja et al. [4]
investigated the impact strength of steel fiber-reinforced concrete with an aspect ratio
of 40 and two strength types, 30 MPa and 50 MPa. The results showed that the impact
strength of all of the samples for the first crack and final fracture increased as the
volume fraction of fibers increased. Song et al. [5] studied the impact resistance of
(HSC) and high strength fiber-reinforced concrete (HSFRC) with a 1% volume
fraction of hooked-end steel fibers with length of 3.5 mm and aspect ratio of 48. The
results showed a 10% and 3% increase in impact resistance of HSFRC and HSC,
respectively. Bindiganavile et al. [6] investigated the effect of the loading rate on the
performance of FRC. They showed that for higher rates of loading, the impact
resistance of the concrete with polypropylene fibers was higher than with steel fibers.
In several investigations it was indicated that usage of fibers, especially steel fiber,
improves impact resistance of concrete [7-8].
Past research has suggested that rubberized concrete could prove to be an ideal
material for energy absorption [9-10]. Adding shredded rubber to concrete softens the
concrete, yielding greater plastic deformation on impact and smaller deceleration
forces [9-11].
The paper presents the effects of adding micro-fiber (polypropylene and steel) and
granulated recycled rubber to concrete on its performances in the hardened state and
on its impact resistance.

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2. DETAIL OF THE EXPERIMENT

2.1. Materials used in the experiment
The reference concrete was produced with the Portland cement CEM I 42.5 R. For
preparation of concrete, the aggregate obtained by mixing three fractions 0/4, 4/8 and
8/16 mm from the river aggregate of the Southern Morava River was used.
Four types of fibers were used for production of micro-reinforced concretes:
polypropylene fibers FIBRILs S120 and FIBRILs F120 produced by “Motvoz”
Grosuplje from Slovenia, steel fibers ZS/N 0.5x30 mm and ZS/N 1.05x50 mm,
produced by “Spajic” d.o.o. Company Negotin from Serbia. The steel ZS/N 0.5x30
mm and ZS/N 1.05x50 mm fibers belong to the group of hook ended fibers, while the
polypropylene fibers of FIBRILs S120 type belong to the group of monofilament
fibers of circular cross sections and smooth surface and the polypropylene fibers of
FIBRILs F120 type belong to the group of fibrillated fibers of rectangle cross sections
and smooth surface. The fibers characteristics are given in the table 1.
Таble 1- Characteristics of polypropylene and steel fibers
Polypropylene fibers Steel fibers
FIBRILs S120 FIBRILs F120 ZS/N 0.5x30 mm ZS/N 1.05x50mm
Characteristic
(monofilament fibers) (fibrillated fibers) (hook ended fibers) (hook ended fibers)
Fiber length 12 mm 12 mm 30 mm 50 mm
Diameter (equivalent) 0.037 mm 0.45 mm 0.50 mm 1.05 mm
Aspect ratio 324 27 60 48
2 2 2
Tensile strength 300,7±31,7 N/mm 274,0±26,9 N/mm 1100±165 N/mm 1100±165 N/mm2

The recycled rubber used was a fraction 0.5-4 mm by the „Tigar“ Pirot
manufacturer. Particle density and bulk density of rubber aggregate in the loose state
were determined according to SRPS B.B8.031:1982 and SRPS B.B8.030:1982 and
amounted to 1150 kg/m3 and 480 kg/m3, respectively. Also used was water reducer
SIKA Viscocrete 3070.
2.2. Concrete mixture composition
Six mixtures for testing fresh and hardened concrete properties were made. The
reference mixture was made by the river aggregate, cement, water and water reducer,
marked with E. The mixture marked R was made with 10% of rubber substitute
instead of the river aggregate. The aggregate substitution was performed by volume.
The mixture marked with PM was made with addition of polypropylene
monofilament fibers FIBRILs S120, PF with addition of polypropylene fibrillated
fibers FIBRILs F120, S30 with addition of steel hook ended fibers ZS/N 0.5x30 mm
and S50 with addition of steel fibers with hook ended fibers ZS/N 1.05x50 mm. The
particle size distribution of basic fractions of aggregates was the same for all the
mixtures, with the minimum difference for those mixtures in which a part of fine river
aggregate was replaced with recycled granulated rubber. The mixtures were made

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with the same water /cement ratio ωc = 0.45 and with approximately same consistency
of concrete (slump 90 - 110 mm) which was achieved using superplasticizer. The
compositions of the concrete mixtures are given in the table 2.
Таble 2- Composition of 1m3 of concrete mixtures used in the experiment
Polypropylene
Aggregate Sika Steel fibers
fibers
Series of Rubber Cement Water VSC
specimen
0/4 4/8 8/16 3070 Fibrils Fibrils ZS/N ZS/N
mm mm mm S 120 F 120 0.5x30 1.05x50
kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 kg/m3
E 806 447 537 - 400 177,6 2,40 - - - -
R 631 449 540 78 404 178,8 3,03 - - - -
PM 806 447 537 - 400 177,4 2,60 0,91 - - -
PF 808 448 538 - 401 177,9 2,60 - 0,91 - -
S30 803 446 536 - 399 176,8 2,80 - - 25,0 -
S50 801 445 534 - 398 176,3 2,80 - - 25,0

3. EXPERIMENTAL RESEARCH
The impact resistance of concrete was tested by the so called. „Drop-weight test“
according to the recommendations of professor Ukrainczyk [12] – adapted to the
requirements of fiber reinforced concretes. A similar test was performed in the paper
[13]. The test setup is displayed in figure 1, and the procedure is as follows: a
constant mass 3kg weight is dropped on the sample from the constant height of 30
cm. The test specimen is a concrete slab having dimensions 40×40×6 cm fixed inside
a steel frame, anchored to the floor. After each weight impact, a visual macroscopic
examination of concrete surface is conducted, for the purpose of detection of potential
damage on the sample. In this case, the damage is considered a clearly visible crack,
occurring on the lower surface of the concrete sample.

Figure 1 – Test setup of concrete impact resistance testing by the „Drop-weight“ method

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The criterion for evaluation of the testing results is related to the number of weight
impacts until the onset of the first crack (N1), as well as to the number of weight
impacts until the failure of the slab (N2). For this purpose, the failure comprises either
the complete propagation of a crack across the full height of the sample or a total
failure (actual breaking) of the sample. The tests were performed on three specimens
of each batch. Each specimen was tested to the maximum number of 40 impacts,
unless the failure occurred prior to that. On the basis of the number of registered
weight impacts was calculated the magnitude of energy expanded for the onset of the
first cracks on the sample (E1), i.e. the total energy corresponding with the failure of
the material (E2) according to the formula:
EN  N  E  n  m  g  h [J ] (1)
where E – energy consumed , corresponding to one weight impact,
EN – total energy after N weight impacts,
m- weight mass – impact mass (m=3,0 kg),
g – Gravitational acceleration (g=9,81m/s2),
h – initial height of the weight (h=0,30 m).
The consistency was measured on the fresh concrete by the slump test according
to SRPS ISO 4109:1997, the bulk density according to SRPS ISO 6276:1997 and air
content of freshly mixed concrete according to SRPS ISO 4848:1999. The
compressive strength and bulk density of hardened concrete were tested on the cubes
with 150 mm sides according to SRPS ISO 4012:2000, the flexural strength on the
prisms with dimensions 100 x 100 x 400 mm according to SRPS ISO 4013:2000, the
tensile splitting strength on cylindrical cores Ø150×300 mm according to SRPS ISO
4108:2000.

4. RESULTS OF EXPERIMENTAL RESEARCH

The tests results of fresh and hardened concrete are presented in the tables 3 and 4.
Таble 3- Characteristics of concrete in fresh state
Series of Density Air content
Slump class
specimen [kg/m3] [%]
E 2370 S3 (110 mm) 3,1
R 2285 S3 (105 mm) 4,1
PM 2370 S3 (100 mm) 3,5
PF 2375 S3 (95 mm) 3,6
S30 2390 S2 (90 mm) 3,4
S50 2385 S3 (100 mm) 3,3

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Таble 4- Characteristics of concrete in hardened state
Compressive The energy
Flexural Splitting tensile The energy
Series of Density strength [MPa] strength strength consumed for the
consumed for
specimen [kg/m3] onset of the first
28 days 90 days [MPa] [MPa] the failure [J]
crack [J]
E 2364 45,23 60,89 5,68 4,71 88,3 185,43
R 2274 33,11 43,78 4,72 3,67 114,79 158,94
PM 2364 45,56 63,23 6,04 5,36 132,45 291,39
PF 2367 42,67 63,78 6,12 5,30 150,11 309,05
S30 2380 44,11 64,11 6,22 5,44 220,75 > 353,20
S50 2376 43,56 63,11 6,08 5,24 194,26 309,05

5. DISCUSION OF RESULTS AND CONCLUSION

As it can be seen in table 3, the highest demand for superplasticizer, so that the
planned slump could be achieved, was observed in the concrete mix in which partial
replacement of fine river aggregate with granulated recycled rubber was performed.
It is a logical consequence of reduction of aggregate particles below 0,5mm, because
the replacement of the natural aggregate fraction 0-4 mm was done by the recycled
granulated rubber having fraction 0,5-4 mm. It can also be seen in the table 3 that for
each type of concrete mixes, there was an increased demand for superplasticizer if the
concretes were micro-reinforced, more so in case of the concretes with steel fibers.
Based on the test results provided in table 3, it can be concluded that partial
replacement of fine river aggregate with recycled granulated rubber to great extent
influenced the reduction of density of compacted fresh concrete (amounting to 3,59%
in comparison to the reference concrete). The reason for this is far lower density of
recycled granulated rubber (1150kg/m3) in comparison to the density of fine river
aggregate (2630kg/m3), as well as somewhat higher percentage of air content in fresh
concrete mixture (table 4). The addition of polypropylene fibers, had a negligibly
lower effect on the variation of density of compacted fresh concrete.
Based on the test results provided in table 3, it can be concluded that the partial
replacement of the natural fine aggregated with recycled granulated rubber caused the
increase of air content of fresh concrete. This is explained by the fact that in the
concrete mixture there is a lack of small particles of 0,5mm which could fill the
empty space between the coarse aggregate grains, because the replacement of the
natural aggregate of fraction 0-4 mm was performed by the recycled granulated
rubber fraction of 0,5-4 mm. The addition of polypropylene and steel fibers had only
a small influence on the variation of air content in fresh concrete, which was
negligibly increased. This effect was more prominent in case when higher quantity of
fibers is added (regardless of their kind and type).
Partial replacement of fine river aggregate with granulated recycled rubber
contributed to the significant decrease of compressive strength. Analyzing the

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obtained results in the table 4, it was stated that in case of the concretes with rubber,
the decrease of compressive strength in respect to the reference concrete is 23,5% at
the age of concrete of 28 days, i.e. 28,1% at the age of 90 days. As for the
reinforcement of concrete with microfibers, it can be said that both polypropylene and
steel fibers provided a small contribution to the increase of compressive strength. The
polypropylene monofilament fibers contribution to the increase of compressive
strength amounted to 0,8% (3,8%), while the contribution of the polypropylene
fibrillated fibers amounted to 2,1% (4,8%) at the concrete age of 28 (90) days. As for
the hook ended steel fibers, the short fibers contribution to compressive strength
amounted to 0,6% (5,3%), while the long fibers contribution amounted to 3,2%
(3,7%) at the age of concrete of 28 (90) days.
As it is already known, the addition of fibers to the concrete should primarily
provide higher tensile strength of concrete, as it was confirmed in this paper based on
the test results presented in table 4. As in case of the concretes made with partial
replacement of fine river aggregate with recycled granulated rubber, the obtained
values of flexural strength were expectedly lower than in the case of the reference
concrete. Partial replacement of the river aggregate with the granulated recycled
rubber in concrete contributed to the drop of flexural strength in the amount of 16,9%.
As for the reinforcing of concrete with microfibers, the polypropylene monofilament
fibers contributed to the flexural strength increase of 6,3%, while the polypropylene
fibrillated fibers contribution amounted to 7,8%. In case of the steel fibers with
hooked ends, the short fibers contributed to the increase of flexural strength of 9,5%,
while the long fibers contribution amounted to 7,0%.
Partial replacement of fine river aggregate with granulated recycled rubber in
concrete contributed to the decrease of splitting tensile strength of 22,1%. As for the
micro reinforced concrete, the polypropylene monofilament fibers contributed to the
increase of splitting tensile strength in the amount of 13,8%, while the contribution of
polypropylene fibrillated fibers amounted to 12,5%. In case of the hook ended steel
fibers, the short fibers contributed to the increase of splitting tensile strength in the
amount of 15,5%, while the long fibers contribution amounted to 11,3%.
Partial replacement of fine river aggregate with granulated recycled rubber in
concrete provides to concrete higher absorption capacity of impact load prior to the
onset of the first crack. After the initial damage is made, the crack propagation is
accelerated, and the sample fails after a lower number of weight impacts. This is
explained by the fact that rubber has better capacity to absorb impacts and vibrations
than concrete, so by being present in the concrete composite, it makes the composite
surface more elastic. Due to the increased elasticity of the concrete surface, the
kinetic energy of the weight after the initial impacts is transformed into the elastic
deformation of the sample, while only a small portion of that energy is expended to
creation of permanent deformation of concrete. After the onset of the first crack, the
damage propagation is accelerated due to the weaker tensile forces in the concrete
composite with granulated rubber (as confirmed by the tensile strength tests).

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Fiber reinforced concretes are more resistant to impact load in comparison to the
non-reinforced concretes, regardless of the type of added fibers. Steel and propylene
fibers contributed to the increase of impact resistance of concrete both in the terms of
increase of absorbed energy until the onset of an initial damage (first cracks) and in
the sense of maintaining serviceability during a protracted period of exposure to
impact loads after the onset of the first crack. Steel hooked-end fibers contributed
more to this type of concrete strength than the polypropylene ones, whereby the
concretes with short steel fibers demonstrated better results than the concretes with
long steel fibers. Namely, the steel fibers are better anchored in the cement matrix
than the polypropylene ones, due to their length and fiber ends geometry, thus they
are able to take on and absorb the impact load to a greater extent. Owing to their more
homogenous distribution within the concrete composite, the short steel fibers with
hooked ends provide a better contribution to the increase of impact resistance of
concrete in comparison to the long fibers. As for the polypropylene fibers,
monofilament fibers provided a slightly smaller contribution to the increase of impact
resistance of concrete in comparison with the fibril ones. The quantity of necessary
energy for creation of the first crack of fiber reinforced concretes was 50-80% higher
than the energy expended when testing the reference concrete, while in case of
concretes reinforced with steel fibers, that energy was 120-175% higher. On the other
hand the amount energy required for breaking the sample made with the addition of
polypropylene fibers was for 55-85% higher than the energy expanded for breaking
the reference concrete sample. In case of concrete with steel fibers, the amount of
energy expended for breaking the sample was 65-100% and more than the energy
required for breaking the reference concrete sample. Some of the concrete samples
reinforced with steel fibers did not fail even after 40 weight impacts.

ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry for Science and Technology, Republic of Serbia. This support is
gratefully acknowledged.

REFERENCES
[1] Lau A, Anson M. Effect of high temperatures on high performance steel fibre
reinforced concrete. Cem Concr Res, 2006; 36: p.p.1698–707
[2] Marar K, Eren O, Celic T. Relationship between impact energy and compression
toughness energy of high-strength fiber-reinforced concrete. Mater Let 2001;47:
pp.297-304.
[3] ACI Committee 544. 1R-96. State-of-the-art report on fiber-reinforced concrete.
Detroit: American Concrete Institute; 1996.

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[4] Nataraja MC, Nagaraja TS, Basavaraja SB. Reproportioning of steel fibre
reinforced concrete mixes and their impact resistance. Cem Conc Res 2005;35:
p.p.2350-9.
[5] Song PS, Wu JC, Hawang S, Sheu BC. Assessment of statistical variations in
impact resistance of high-strength concrete and high-strength steel fiber-
reinforced concrete. Cem Conc Res 2005;35: p.p.393-9.
[6] Bindiganavile V, Banthia N. Polymer and Steel Fiber-Reinforced Cementitious
Composites under Impact Loading. ACI Materls J 2001;98(1):339-53.
[7] Mohammadi Y, Carkon-Azad R, Singh SP, Kaushik SK. Impact resistance of
steel fibrous concrete containing fibres of mixed aspect ratio. Constr Build Mater
2009;23: p.p. 183-9.
[8] Zhang MH, Shim VPW, Lu G, Chew CW. Resistance of high-strength concrete
to projectile impact. Int J Impact Engng 2005;31: p.p. 825-41.
[9] Atahan AO, Sevim UK. Testing and comparison of concrete barriers containing
shredded waste tire chips. Mater Lett 2008;62: p.p. 3754–7.
[10] Sallam HEM, Sherbini AS, Seleem MH, Balaha MM. Impact resistance of
rubberized concrete. Eng Res J 2008;31: p.p.265–71.
[11] Hernández-O. F., Barluenga G, Bollati M, Witoszek B. Static and dynamic
behaviour of recycled tyre rubber-filled concrete. Cem Conc Res 2002;32(10):
p.p.1587–96.
[12] Štimer N., Ukrainczyk V.: Model nadsloja industrijskog poda od udarnim
opterećenjem. Zbornik radova sa 12. Slovenskog kolokvija o betonima „Novosti
pri gradnji tlakov“ u organizaciji instituta IRMA, Ljubljana, 2005, str. 49-63.
[13] Zakić D.: Istraživanje parametara duktilnosti i udarne otpornosti sitnozrnih
betona mikroarmiranih sintetiĉkim vlaknima. Doktorska disertacija, Univerzitet
u Beogradu, GraĊevinski fakultet, 2010.

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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 691
1
Ana TROMBEVA-GAVRILOSKA
Meri CVETKOVSKA2
Marijana LAZAREVSKA3

INFLUENCE OF THE TYPE OF REINFORCEMENT ON THE

BEHAVIOR OF FRP MATERIALS AT INDOOR AND ELEVATED
TEMPERATURES
Abstract: Increasing interest about composite materials and their use in the field of civil engineering
offers possibility for development of new innovative materials, which will be used as constructive
elements. The concept of the composite materials itself, offers possibility of effective exploitation of
mechanical characteristics of the separate components till their limit, even in the design process.
Mechanical characteristics of each composite material depend on its components. In this paper
experiments of different series composite materials differed by the type of used reinforcement are
presented. Experimentally observed mechanical characteristics of different types of composite materials
are discussed in dependence on used reinforcment at indoor and elevated temperature.

Кey words: composite materials, mechanical characteristics, experiments, temperature.

.

UTICAJ TIPA ARMATURE NA PONAŠANJE FRP MATERIJALA NA

SOBNOJ I POVIŠENOJ TEMPERATURI
Rezime: Zainteresovanost o kompozitnim materijalima i njihova primena u konstruktivnim elementima u
građevinarstvu nudi mogućnost razvoja novih inovativnih materijala. Koncept kompozitnog materijala,
sam po sebi, nudi mogućnost efekasnog iskoriščavanja mehaničkih karakteristika pojedinih komponenata
do njihove krajne granice, čak i u fazi projektovanja. Mehaničke karakteristike kompozitnog materijala
zavise od njegovih sastavnih komponenti. U ovom radu prikazani su eksperimentalni rezultati dve serije
kompozitnih materijala različitih po vrsti primenjene armature. Eksperimetalno dobijeni rezultati
mehaničkih karakteristika kompozitnih materijala analizirani su u zavisnosti vrste armature na sobnoj i
povišenoj temperuri.

Ključne reči: kompozitni materijali, mehaničke karakteristike, eksperiment, temperatura.

1
Assoc. Prof., Faculty of Architecture, Partizanski odredi 24, Macedonia, agavriloska@arh.ukim.edu.mk
2
Prof., Faculty of Civil Engineering, Partizanski odredi 24, Macedonia, cvetkovska@gf.ukim.edu.mk
3
Assis. Prof., Faculty of Civil Engineering, Partizanski odredi 24, Macedonia, marijana@gf.ukim.edu.mk

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1. INTRODUCTION
A composite material is a combination of two or more other materials, produced as
a mixture of the main two parts as fiber and matrix. Composites can be defined as
polymer matrix reinforced with fibers as reinforcement in one or more directions,
which provide the strength and stiffness, while the resin matrix acts as a binder
providing impact resistance, compressive strength, and corrosion resistance. FRP
composite materials have advantages in comparison to conventional materials, such
as: higher strength to weight ratio, non-corrosiveness and better stiffness to weight
ratio.
The strength and stiffness of the composite materials according to Barbero [1]
depend on the matrix choice, while the strength of the composite material to
compression and tension, in a direction normal to the reinforcement fibers, depend on
the matrix strength, on the strength of the contact surface between the matrix and the
reinforcing fibers and from the defects in the matrix such as holes and micro
fractures.
Many papers that concern composite materials [2, 1, 3] present the excellent
mechanical characteristics of the composite materials. Experimental research work [2,
1, 3] show that the mechanical characteristics of the composite materials depends on
the matrix and fiber reinforcement selection. Despite the fact, that the mechanical
characteristics of the composite materials could be estimated from previous gained
knowledge, the experimental testing should be performed if new composite product is
developing, in order to obtain precise mechanical characteristics. Furthermore, the
experimentally obtained results could give clear view on the behaviour of the
mechanical characteristics due to changes of components or changes of
environmental conditions, and help the designer to analytically predict behaviour of a
complex structure.
This paper presents the experiment test for the tensile properties of two series of
composite materials, which differed according to the fiber reinforcement. Nonlinear
behaviour of the polymers and their properties mainly depend on the “glass
transmission temperature” [4], so the ultimate tensile strength and the initial module
of the elasticity of the composite materials were experimentally determined at at
elevated temperature close to the “glass transmission temperature”. In order to
analyse the influence of the different components on the final mechanical
characteristics of the composite materials the basic mechanical characteristics from
experimentally obtained σ-ε diagrams, such as ultimate tensile strength and module of
elasticity, were determined. Experimental results are analyzed and discussed
depending on the temperature level and depending on the type of reinforcement.

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2. SPECIMENS PREPARATION AND EXPERIMENTAL PROCEDURE

2.1. Components of composite materials and specimen geometry
For the purpose of the research work two different series of thin laminates were
fabricated, which differ by type of reinforcement and by plies of reinforcement. The
laminates were fabricated using two types fiber glass reinforcement in three and two
plies. For production of the fiber reinforced laminates were used the following
materials:
 Polymer matrix: Polyester resin (P), orthoftalic based acid, type DUGAPOL
H230, and
 Fiber reinforcement: Matta (M) with density 0,315 kg/m2, and Rowing (R) with
density 0,535 kg/m2.
Marking of the laminates was according to their components: the first symbol
refers to the type of the matrix (P), the second symbol refers to the number of
reinforcement plies, the third symbol refers to the type of used reinforcement (M or
R) and the last fourth symbol (T) denotes the specimens tested on increased
temperature. Table 1 summarizes the types of composite laminates used in this
research.
Table 1- Components of tested composite laminates
Laminate Matrix Reinforcement plies Reinforcement
P3M Polyester resin 3 Matta
P2R Polyester resin 2 Rowing
Test specimens were cut from fabricated laminates. Their geometry was defined
according to American test standard ASTM D 3039 [5], Figure 1. All test specimens
had a constant rectangular cross section and tabs on each side. These tabs were made
form G11 laminate, epoxy material reinforced with E glass rowing under high
temperature. In order to avoid different surface stresses the bond between tabs and
specimen was made by araldite, epoxy and polyurethane based adhesive with high
extensive properties.
1,5 mm
Δ
1,5mm b
10 mm 170 mm 30 mm
250 mm
Figure 1 - Geometry of composite test specimens
2.2. Experiment test setup
Test procedure was defined in accordance with American test standard ASTM D
3039 [5]. Prior to the tension tests the final surface preparation was carefully
examined for each test specimen. The dimensions of the specimens were measured

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before tension testing and the specimens’ area were determinate at three places in
order to record the average area.
Experiments were performed by using testing machine SCHENCK
HYDROPLUS-PSB, with capacity of 250 kN. Tests were made in range up to 25 kN.
Pressure controllable hydraulic grips were used. Initial trails were made in order to
determinate the most appropriate pressure on the hydraulic grips. The speed of the
testing machine was set to 1 mm/min in order to obtain constant strain rate in the gage
section, which was observed with trail tests. The specimens were inserted in the grips
of the testing machine taking care of alignment of the ripped specimen with the test
direction.
Tension force was determined with force transducer integrated in the testing
machine. The full bridge strain gage type force transducer was used. Head
displacement of the testing machine was determined by displacement transducer of
inductive type. Strain data were determinate using strain gage in longitudinal
direction. In order to reduce heating effects due to the low conductivity of the used
composite materials the strain gage with resistant of 350 , type HBM 10/350LY11,
were selected. The surface preparation and selection of bonding agent for the strain
gage installation was done in the consultation with the strain gage producer. The
temperature compensation was done by adding a passive strain gage, connected in
half-bridge. The force versus head displacement and the force versus strain were
continuously recorded with sampling rate of 50 Hz. The HBM Spider 8 and software
HBM CATMAN 4.0 were used for data acquisition.
Tensile test experiments of the composite materials were conducted at indoor
temperature on 22° C, Figure 2 а), and at elevated temperature on 80° C. Tested
specimens at elevated temperature were heated up to 80° C in temperature chamber.
In order to avoid a cooling of the specimens during the tensile tests experiments were
conducted in temperature chamber.

3
1 1

1
1 2 3 2 4

a) b)
Figure 2 - Testing machine and equipment for tensile test of FRP specimens at:
a) indoor temperature; b) increased temperature:
1) testing machine; 2) computer; 3) temperature chamber; 4) acquisition unit

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3. RESULTS AND DISCUSION

The tensile testing has been performed on two different series of specimens, each
tested at indoor temperature and at elevated temperature. For the purpose of the
experiment three specimens of each serial were tested. Geometry and experimentally
obtained results for tested FRP specimens are summarized in Table 2.
Table 2 - Geometrical and mechanical properties of tested FRP specimens
Tensile Module of Average Average module
b Δ tensile
Specimen strength elasticity of elasticity
[mm] [mm] strength
[MPa] [МPa] [МPa]
[MPa]
P3M_1 25 3 37,71 6600
P3M_2 24,5 2,8 34,68 6570 35,96 6583,3
P3M_3 25 2,9 35,48 6580
P2R_1 25 1,5 87,33 12200
P2R_2 25,1 1,6 81,77 10850 86,02 11445
P2R_3 25,2 1,6 88,96 11285
P3MT_1 23 4 29,29 1810
P3MT_2 23 4 26,72 1815 27,74 1807
P3MT_3 23,5 4 27,20 1795
P2RT_1 25 1,7 39,22 3900
P2RT_2 25 1,6 81,9 3610 60,58 3653
P2RT_3 24,9 1,5 60,61 3450
Influence of the elevated temperature on the mechanical properties of the
composite materials have been analysed through comparison of σ-ε diagrams of
appropriate series specimens experimentally tested at indoor temperature and at
elevated temperature, Figure 3.
40 90

35 80

70
30
Tensile stress [MPa]

Tensile stress [MPa]

60
25
50
20
40
15
30
10 P3M_1 P3MT_1 P2R_1 P2RT_1
20
P3M_2 P3MT_2 P2R_2 P2RT_2
5 10
P3M_3 P3MT_3 P2R_3 P2RT_3
0 0
0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5
Elongation [%] Elongation [%]
a) b)
Figure 3 - Comparison of σ-ε diagrams at indoor temperature and at elevated temperature: а)
series P3M and P3MT, b) series P2R and P2RT
From the Figure 3 could be concluded that σ-ε behaviour of the composite
materials axially loaded in tension is sensitive to temperature change and the results
are decreased mechanical properties of the composite materials tested on elevated

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temperature. As a result of reduction of the module of elasticity, caused by

temperature depend behaviour of the polymer matrix, increased strain of the
composite materials tested at elevated temperature could be noticed. The results show
that internal stresses in the composite material between matrix and fibers, caused by
different temperature strains, lead to reduction of the ultimate tensile strength of FRP
specimens tested at increased temperature.
In order to observe the influence of the type of reinforcement on the mechanical
properties of the composite materials, comparative analyses of the experimentally
obtained results were carried out. Influence of the used fiber reinforcement has been
analyzed through comparison of the experimental results of series specimens P3M
and P2R at indoor temperature,Figure 4a) and at the elevated temperature, Figure 4b).
90 90
P3M_1 P2R_1 P3MT_1 P2RT_1
80 80
P3M_2 P2R_2
P3MT_2 P2RT_2
70 P3M_3 P2R_3 70
P3MT_3 P2RT_3
60 60
Tensile stress [MPa]
Tensile stress [MPa]

50 50

40 40

30 30

20 20

10 10

0 0
0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5 3
Elongation [%] Elongation [%]
a) b)
Figure 4 - σ-ε diagrams for tensile test specimens for series P3M and P2R: a) at indoor
temperature; b) at elevated temperature
The analyses of σ-ε diagrams, Figure 4 and results presented in Table 2 show that
composite materials reinforced with rowing have approximately two times higher
tensile strength, module of elasticity and maximal strain in comparison with the
composite materials reinforced with matta regardless of temperature level.

a) b)
Figure 5 - Failure modes of tested specimens at indoor temperature: a) series P3M; b) series
P2R

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The failures of tested FRP specimens at indoor temperature were sudden and
brittle and experiment show that the failure modes differed by the type of the used
reinforcement. Standard description of the failure modes was chosen using the three-
part failure mode code, according to American standard ASTM D 3039 [5]. The
failure mode for the test specimens reinforced with matta was denote as LAT (Lateral
At grip/tab Top), Figure 5 a), while the failure mode of the test specimens reinforced
with rowing was denote as LGM (Lateral Gage Middle), Figure 5 b).

4. CONCLUSIONS
This paper presents results from the experimental tests of two series of composite
materials, subjected on axial tension at indoor temperature and at elevated
temperature. The basic mechanical characteristics from σ-ε diagrams, ultimate tensile
strength and module of elasticity, were determined in order to analyse the influence of
the increased temperature and type of reinforcement on the final mechanical
characteristics of the composite materials.
The analysis shows that the mechanical properties of the composite materials are
sensitive to the temperature. Increased temperature leads to decreasing of the initial
tensile strength, the ultimate tensile strength and the module of elasticity followed by
increasing of the strain. The experimental results show that the fiber reinforcement
selection, strongly influence on the mechanical characteristics of composite materials.
Composite materials reinforced with rowing have higher tensile strength as a result of
the great bearing capacity in the direction of the applied tensile force. The analysis
shows that the ultimate tensile strength of the composite materials depends on bearing
capacity of the reinforcement at whole. Furthermore, the experiments show that the
failure mode strongly depends on the choice of the reinforcement used for the
composite material.

REFERENCES
[1] Barbero, E. J. (1999). Introduction to Composite Materials Design, Philadelphia:
Taylor & Francis.
[2] Russo, A., Zuccarello, B. (2007). Experimental and Numerical Evaluation of the
Mechanical Behaviour of GFRP Sandwich Panels. Composite Structures, Vol.
81: pp. 575-586.
[3] Chawla, K. K. (1998). Composite Materials, New York: Springer-Verlag.
[4] Žarnić, R. (2003). Lastnosti gradiv, Ljubljana: Potens.
[5] ASTM D3039/D 3039M-08 (2008): Standard Test Method for Tensile Properties
of polymer Matrix Composite Materials, ASTM International.

[288]
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OF BUILDINGS
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
1 2
Milica BUBNJEVIĆ , Vladimir ŢIVALJEVIĆ ,
Vanja VUĈINIĆ3, Dunja KRTINIĆ4,
Mina LJUBISAVLJEVIĆ5, Srbislav BABIĆ6,
Miloš ŠEŠLIJA7, ĐorĊe LAĐINOVIĆ8

THE ASSESSMENT OF ROAD PEDESTRIAN BRIDGE ON NEMILA

STREAM IN MELJINE
Abstract: Determination of the real condition of structure of pedestrian bridge in Meljine as well as
suggestion of possible repairing measures are given in the paper. In order to define required technical
documentation a complete measurement of structural elements has been carried out. Afterwards, a
detailed visual inspection of accessible structural elements was carried out in order to determine all
existing damages. Based on all mentioned activities it has come to a conclusion about current condition
of the structure and possible repairing measures have been given.

Key words: assessment, steel bridge, damages, repairing measures.

PROCENA STANJA DRUMSKO-PEŠAČKOG MOSTA NA POTOKU

NEMILA U MELJINAMA
Rezime: U okviru rada je izvršena procena stanja i date su globalne preporuke za sanaciju drumsko-
pešaĉkog mosta u Meljinama. Najpre je obavljeno merenje svih dimenzija kako bi se formirale
karakteristiĉne osnove i preseci. Potom je izvršen detaljan vizuelni pregled svih dostupnih elemenata
konstrukcije mosta gde su uoĉena oštećenja. Na osnovu vizuelnog pregleda je dat zakljuĉak o trenutnom
stanju u kome se objekat nalazi i predlog mera sanacije sa ciljem vraćanja objekta u projektovano stanje.

Ključne reči: procena stanja, ĉeliĉni most, oštećenja, mere sanacije.

1
B. Sc, Student, mmbubnjevic@sbb.rs
2
B. Sc, Student, zivaljevic.vladimir@gmail.com
3
B. Sc, Student, vucinic_vanja@yahoo.com
4
B. Sc, Student, the.thorn_bird@yahoo.com
5
B. Sc, Student, ljubisavljevicmina@gmail.com
6
B. Sc, Student, srbislavbabic88@gmail.com
7
M. Sc, Teaching Assistant, slavijasrb@gmail.com
8
Full-time Professor, ladjin@uns.ac.rs
1,2,3,4,5,6,7,8
University of Novi Sad, Faculty of Technical Sciences, Department of civil engineering and geodesy, Trg
Dositeja Obradovića 6 21000 Novi Sad

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1. INTRODUCTION AND BASIC INFORMATION ABOUT THE BRIDGE

Numerous damages appeared in the past period on the steel structure of the bridge
owing to lack of maintenance and the permanent exposure to harsh marine
environment. Damages appeared as corrosion of steel material, significant reduction
of cross-sections and deformation of steel sheets.
In order to determine level and couse of damages as well as the type of repair
works further activities were carried out:
 Complete measuring of all structural elements, defining all important plan
views, cross and longitudinal sections along with re-establishing permanent
technical documentation using АutoCAD software. It has been assumed that
the bridge dates from 20th Century.
 Detailed visual inspection of accessible structural elements in order to
determine the level of damages as well as possible repairing measures,
together with technical description with damage clasification, graphical
presentation and photographs of detected defects.
 Examination of all assembled information and assessment of the structure
along with proposal of possible repairing measures.

Figure 1 - View of a road pedestrian steel bridge on Nemila stream (B-side)

Figure 2 – Model of a road pedestrian steel bridge on Nemila stream

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Figure 3 – Plan view of the bridge in level of cross girders

Figure 4 - Longitudinal section of the bridge and denotement of vertical axes

2. DETAILED EXAMINATION OF THE BRIDGE STRUCTURE

2.1. Main longitudinal girders
A detailed visual inspection of main longitudinal girders showed further damages:
 Surface corrosion;
 Pitting corrosion;
 Delamination and spalling of steel material due to corrosion;
 Corrosion on the joints of longitudinal girders and their cross stiffeners.

Figure 5 – Progress of the surface corrosion, Figure 6 – Surface and spot corrosion
delamination

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2.2. Secondary longitudinal girders

A detailed visual inspection of secondary longitudinal girders showed further
damages:
 Surface corrosion;
 Delamination and spalling of steel owing to corrosion;
 Corrosion on the joints of steel sheets;
 Reduction of cross-section area of steel profiles and local holes on metal
sheets owing to corrosion;

Figure 7 - Delamination and spalling of steel Slika 8 - Reduction of cross-section,

deformation of metal sheet, delamination
2.3. Main cross girders
A detailed visual inspection of main cross girders showed further damages:
 Surface corrosion;
 Corrosion on the joints of steel sheets;
 Deformation and warping of bottom flanges.

Figure 9- Surface corrosion Figure 10 - Deformation of steel sheet,

delamination

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2.4. Secondary cross girders

A detailed visual inspection of secondary cross girders showed further damages:
 Deep corrosion;
 Reduction of cross-section area of steel profiles;
 Delamination and spalling of steel owing to corrosion;
 Deformation of steel sheets;
 Accumulation of insect`s nests along girders.

Figure 11 - Delamination of steel Figure 12 - Delamination of steel,

reduction of cross-section area,
deterioration of concrete
2.5. Supports
Bridge structure is supported by steel rolling supports. A detailed visual inspection
revealed a significant corrosion of supports themselves as well as the lower part of
ribs and flanges of the main longitudinal and cross girders in the area above the
supports.

Figure 13- Corrosion and deterioration of Figure 14 – View of moveable support in

support in axis 6, steel delamination axis 0

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2.6. Superstructure steel truss

A detailed visual inspection of steel truss showed further damages:
 Surface spalling of protective coating;
 Pitting corrosion;
 Surface corrosion;
 Delamination and spalling of steel owing to corrosion, particularly in the joints
of steel sheets;
 Reduction of cross-section area of steel profiles and local holes on metal
sheets owing to corrosion;

Figure 15 - Characteristic damages of superstructure truss (axis A)

Figure 16 - Characteristic damages of Figure 17 - Characteristic damages of

diagonals, diagonal D2/B diagonals, dijagonal D4/B

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3. EVALUATION OF THE CONDITION OF BRIGDE STRUCTURE AND

GLOBAL REPAIRING MEASURES
Based on analysis of information obtained by visual inspection of accessible
elements of superstructure and substructure of steel road pedestrian bridge on Nemila
stream in Meljine, following conclusions were made:
 The durability of bridge structure is significantly reduced due to advanced
corrosion process and permanent exposure to harsh marine environment.
Durability is endangered owing to damage progress that is vastly manifested as
steel delamination and scaling along with reduction of cross-section areas.
 Condition of structural elements does not endanger bearing capacity and
stability of the bridge structure for exploitation load.
 Condition of supports still does not directly endanger the bearing capacity and
stability of the bridge structure.
 Estimated general condition of the bridge is the consequence of a long
utilization of the bridge, lacking of maintenance as well as the aggressive
influence of the marine environment;
In order to restore bridge structure in a technically correct and functional condition
with adequate durability during future exploitation, it is necessary to undertake
decisive repairing measures.
Repair works should include the replacement of all corroded parts of steel
structure, complete cleansing of the bridge structure from surface corrosion and
application of protective anti-corrosion coating. In order to increase the durability of
supports, it is necessary to renew the anti-corrosion protective layer.
Based on all assembled information and global proposals ahead of this Study, it is
necessary to define detailed Rehabilitation project of bridge structure.

ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

REFERENCES
[1] D. Spasić (1949): Zidani mostovi, Izdavaĉ Nauĉna knjiga, Beograd, str. 2013.
[2] Katedra za betonske konstrukcije i mostove (2008): Mostovi, Izdavaĉ Sveuĉilište
u Spriltu, str. 148.
[3] L. Simov (1971): Drveni konstrukcii i mostovi, Izdavaĉ Univerzitet "Kiril i
Metodij", Skoplje, str. 146.
[4] M. Gojković (1989): Stari kameni mostovi – anatomija, patologija, zaštita,
sanacija, konzervacija", Izdavaĉ Nauĉna Knjiga, Beograd, str. 239.

[296]
iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[5] O. Doklestić, (2013): Most na rijeci Sutorini, Zbornik radova iz nauke, kulture i
umjetnosti "Boka" – br. 33, str. 243-258.
[6] O. Doklestić, M. Balabušić, V. Trebješanin (2015): Matkovića most –
konstrukcija, oštećenja, moguća sanacija, Zbornik radova sa IX MeĊunarodnog
nauĉno-struĉnog savetovanja "Ocena stanja, odrţavanje i sanacija graĊevinskih
objekata i naselja, Editor prof. dr R. Folić, Zlatibor, maj 2015, str. 173-178.
[7] V. Radonjanin, M. Malešev, T. Koĉetov-Mišulić, R. Lekić (2010): Oštećenja i
sanacija zidanih, ĉeliĉnih i drvenih konstrukcija, Skripta sa predavanja, Fakultet
tehniĉkih nauka, Novi Sad, str. 124.
[8] V. Radonjanin, M. Malešev, B. Matić (2010): Upravljanje mostovima, Skripta sa
predavanja, Fakultet tehniĉkih nauka, Novi Sad, str. 136.

[297]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
1 2
Mina LJUBISAVLJEVIĆ , Dunja KRTINIĆ ,
Srbislav BABIĆ3, Milica BUBNJEVIĆ4,
Vladimir ŢIVALJEVIĆ5, Vanja VUĈINIĆ6,
Miloš ŠEŠLIJA7, Vlastimir RADONJANIN 8

THE ASSESSMENT AND PROPOSAL OF REPAIR OF STONE

BRIDGE ON THE RIVER SUTORINA IN HERCEG NOVI
Abstract: In this paper evaluation of the real condition of structure of bridge on the river Sutorina in
Herceg Novi dating from 19. century is given. Lack of maintenance throughout the period of exploitation
caused many damages on structure of the bridge. A detailed visual inspection of accessible structural
elements was carried out in order to determine the cause and level of these damages as well as possible
repairing measures. Based on examinations carried out ˝in situ˝ and in laboratory current condition of
structure is determined and possible repairing measures are proposed.

Key words: assessment, stone bridge, damages, repair.

PROCENA STANJA I PREDLOG SANACIJE KAMENOG MOSTA NA

RECI SUTORINI U HERCEG NOVOM
Rezime: U radu je prikazana procena stanja mosta iz 19. veka na reci Sutorini u Herceg Novom. U
proteklom eksploatacionom periodu na konstrukciji mosta su se pojavila brojna oštećenja usled
neodrţavanja. Radi utvrĊivanja uzroka i stepena oštećenja kao i vrste sanacionih radova sproveden je
makroskopski pregled dostupnih elemenata konstrukcije mosta. Na osnovu ispitivanja rezultata dobijenih
na terenu i u laboratoriji procenjeno je stanje konstrukcije mosta i dat je predlog sanacionih mera.

Ključne reči: procena stanja, kameni most, oštećenja, sanacija.

1
B. Sc, Student, ljubisavljevicmina@gmail.com
2
B. Sc, Student, the.thorn_bird@yahoo.com
3
B. Sc, Student, srbislavbabic88@gmail.com
4
B. Sc, Student, mmbubnjevic@sbb.rs
5
B. Sc, Student, zivaljevic.vladimir@gmail.com
6
B. Sc, Student, vucinic_vanja@yahoo.com
7
M. Sc, Teaching Assistant, slavijasrb@gmail.com
8
Full Professor, radonv@uns.ac.rs
1,2,3,4,5,6,7,8
University of Novi Sad, Faculty of Technical Sciences, Department of civil engineering and geodesy, Trg
Dositeja Obradovića 6 21000 Novi Sad

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1. INTRODUCTION
Stone bridge on the river Sutorina is constructed for pedestrian traffic and
subsequent to this in the nearby area a concrete bridge was built for vehicular traffic.
It is regarded as the biggest bridge on the territory of Herceg Novi (Figure 1). The
bridge is dating from period during which Boka Kotorska was under the rule of
French government and it is supposed that the construction begun in July 1808. In
that time, purpose of bridge was mainly for vehicular traffic.

Figure 1 – Front view of the bridge on the river Sutorina

Numerous damages appeared in the past period on the structure of the bridge
owing to lack of maintenance. Characteristic damages appeared as falled out mortar
from joints, local mechanical damages, etc.
In order to determine level and cause of damages as well as the type of repair
works further activities were carried out:
 Complete measuring of all structural elements, defining all important plan
views, cross and longitudinal sections along with re-establishing permanent
technical documentation using АutoCAD software;
 Detailed visual inspection of accessible structural elements in order to
determine the level of damages as well as possible repairing measures,
together with technical description with damage classification, graphical
presentation and photographs of detected defects;
 Taking of stone sample form different structural elements;
 Examination of all assembled information and assessment of the structure
along with proposal of possible repairing measures.

2. BASIC INFORMATION ABOUT THE BRIDGE

Stone bridge is supported by four supports, two abutments at each bank of the
river and two river supports. Two arches bridge the river, while the third arch is
placed on the left bank and place above it is used as a parking space. The third arch
was accessible for visual inspection only at side A. Total length of the bridge (not
including place above third arch) is 29 m.

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Bridge structure is consisted of three simply supported arches.

In nearby area a concrete river bed was built. During construction of adjacent
concrete bridge, a concrete plateau was built around the stone bridge on the river
Sutorina (Figure 3).
On the side A span of arch 1 is 7.8 m and span of arch 2 is 8 m. Rise of both
arches is 3.1 m. Height of voussoirs of arches 1 and 2 on the side A is 35 cm. In axis
0 and 1 there is cutwater of prismatic shape with upper part of pyramidal shape.
Height of cutwater is 190 cm and width is 320 cm and height of upper part is 90 cm.
Transition from cutwater to upper part is emphasized with stone of different color
(Figure 4).
On the side B span of arch 1 is 7.8 m and span of arch 2 is 8 m. Rise of both
arches is 3.1 m. Height of voussoirs of arches 1 and 2 on the side B is 35 cm. On
spandrel wall there is archivolt whose width is 10 cm.
Width of both vaults is 3.2 m.

Figure 2 – Plan of the bridge on the river Sutorina with indication of axis

In nearby area a concrete river bed was built. During construction of adjacent
concrete bridge, a concrete plateau was built around the stone bridge on the river
Sutorina (Figure 3).

Figure 3 – Concrete river bed of the bridge on the

Figure 4 –Aesthetic use of stone
river Sutorina

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3. DETAILED EXAMINATION OF THE BRIDGE STRUCTURE

A detailed visual inspection of following structural elements was carried out:
 Supports;
 Intrados;
 Archivolt;
 Spandrel wall;
 Joints;
 Voussoir;
 Cutwater.
Examination results are systemized and presented for each structural element. A
detailed visual inspection showed following damages:
 Falling out mortar from joints;
 Local mechanical damages;
 Layers of calcium carbonate;
 Vegetation;
 Cracks in spandrel walls.
3.1. Side A
At side A no empty joints were registered. On spandrel wall, beside vegetation,
two cracks were registered above arch 1 (Figure 5) and arch 2 going through joints
and following the line of arch. Since these two cracks were registered on both sides, it
is concluded that they outspread through entire width of vault. Supposedly, this was
due to subsidence of support in axis 2 caused by earthworks during construction of
the bridge in the nearby area.
In addition, poor and empty joints due to falling out mortar were registered (Figure
6).

Figure 5 – Cracks above arch 1

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Figure 6 – Mechanical damages, vegetation and empty joints on cutwater 2 (side A)

3.2. Side B
On side B above-mentioned cracks were registered as well as vegetation and
empty joints (Figure 7).

Figure 7 – Damages on side B (cracks, vegetation and joints without mortar)

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3.3. Vault 1 and vault 2

Stone used for building vaults 1 and 2 is of prismatic shape with rugged surfaces.
Surface of vault is warped. Larger surface area is covered with layers of calcium
carbonate. In addition, vegetation and empty joints were registered (Figure 8).

Figure 8 – Damages of vault (empty joints, layers of calcium carbonate and vegetation)

3.4. Roadway of the bridge

Embankment between two spandrel walls is combination of earth and stone. On
the surface of the roadway vegetation was registered. Above spandrel wall, left of
arch 2, missing of the stone curb was registered (Figure 8).
In the figure 9 a damage scheme of all structural elements is shown.

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VAULT 1 VAULT 2
0 1 2
Empty joints Vegetation
Empty joints

0 Vegetation Vegetation 2
Vegetation
1

SIDE A 1
Empty joints
Crack Crack
0
2

0 2
1
Figure 9 – A damage scheme of developed vault surface and side A

No defect was registered on the structure of the bridge.

4. VISUAL EXAMINATION AND ASSESMENT OF VOLUMETRIC

WEIGHT OF STONE USED FOR BUILDING
Visual examination of stone sample showed that bridge is made of softer
limestone of a good quality. Limestone is of chemical composition of carbonate
sediment, made of mineral calcite. Due to different origin, limestone is of various
structures, textures and porosity. Bulk density, determined with samples of irregular
shape taken from cutwater in the axis 2, is 2672 kg/m3.

5. CONCLUSION
Based on analysis of information obtained by visual inspection of accessible
elements of superstructure and substructure of stone bridge on the river Sutorina,
following conclusions were made:
 The durability of bridge structure is significantly reduced due to empty joints
as well as due to mechanical damages;
 Bearing capacity and stability of the bridge structure for exploitation load are
endangered due to cracks in spandrel wall;

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 Estimated general condition of the bridge is the consequence of a long

utilization of the bridge, lacking of maintenance as well as the aggressive
influence of the marine environment;
 Condition of supports after arrangement of concrete river bed does not
endanger the bearing capacity and stability of the bridge structure.
In order to restore bridge structure in a technically correct and functional condition
with adequate durability during future exploitation, it is necessary to undertake
decisive repairing measures.
Repair works should include complete cleansing of the bridge structure surface
from layers od calcium carbonate and vegetation; re-feeling of empty joints with
appropriate lime-cement mortar as well as injecting of cracks.

ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

REFERENCES
[1] D. Spasić (1949): Zidani mostovi, Izdavaĉ Nauĉna knjiga, Beograd, str. 2013.
[2] Katedra za betonske konstrukcije i mostove (2008): Mostovi, Izdavaĉ Sveuĉilište
u Spriltu, str. 148.
[3] L. Simov (1971): Drveni konstrukcii i mostovi, Izdavaĉ Univerzitet "Kiril i
Metodij", Skoplje, str. 146.
[4] M. Gojković (1989): Stari kameni mostovi – anatomija, patologija, zaštita,
sanacija, konzervacija", Izdavaĉ Nauĉna Knjiga, Beograd, str. 239.
[5] O. Doklestić, (2013): Most na rijeci Sutorini, Zbornik radova iz nauke, kulture i
umjetnosti "Boka" – br. 33, str. 243-258.
[6] V. Radonjanin, M. Malešev, T. Koĉetov-Mišulić, R. Lekić (2010): Oštećenja i
sanacija zidanih, ĉeliĉnih i drvenih konstrukcija, Skripta sa predavanja, Fakultet
tehniĉkih nauka, Novi Sad, str. 124.
[7] V. Radonjanin, M. Malešev, B. Matić (2010): Upravljanje mostovima, Skripta sa
predavanja, Fakultet tehniĉkih nauka, Novi Sad, str. 136.

[305]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
1
Predrag L. POPOVIC
James P. DONNELLY2

RENOVATION ADDS SPACE AND VALUE TO PARKING

GARAGE
Abstract: Innovative scheduling and post-tensioning modifications were involved in the expansion of a
garage in order to provide additional parking for an otherwise overcrowded facility. This was done by
providing a new internal ramp to connect the second level of the garage to the new area of Roof Level
parking. Complexities of this project included the shoring and construction of the new ramp over an
operative existing ramp, and the demolition of a portion of the post-tensioned roof deck slab over the
operating ramp while maintaining the capacity of the post-tensioned roof deck slab in other areas. The
construction was completed in four months.

Кey words: parking garage, post-tensioning, repair, shoring.

REKONSTRUKCIJA OBEZBEĐUJE PROSTOR ZA PARKIRANJE I

PODIŽE VREDNOST GARAŽE
Rezime: Proširenje postojeće garaže je ostvareno inovativnim modifikacijama prednapregnutih betonskih
ploča izvedenim u fazama. Unutrašnja rampa je povezala drugi sprat garaže sa krovom. Kompleksnost
projekta čine skela i izvodjenje nove rampe iznad postojeće rampe sa saobraćajem, kao i rušenje dela
krovne prednapregnute ploče u fazama uz očuvanje kapaciteta krovne ploče u drugim zonama. Projekat
je završen za četiri mececa.

Ključne reči: garaža, prednapregnuti beton, sanacija, skela.

1
Vice President and Senior Principal, Wiss, Janney, Elstner Associates, Inc., Northbrook, Illinois,
ppopovic@wje.com
2
Principal, Wiss, Janney, Elstner Associates, Inc., Northbrook, Illinois, jdonnelly@wje.com

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1. DESCRIPTION OF STRUCTURE
Park Place Tower, a 57-story residential high-rise on Chicago’s North Side, has
900 deluxe apartments. However, until the summer of 1997, its attached two-story,
155,000-square-foot parking garage contained only 600 parking stalls. Therefore,
parking was in great demand, and the garage was frequently overcrowded. During
overnight hours, cars were often parked in the aisles and drive lanes.
The owner consulted our firm, Wiss, Janney, Elstner Associates, Inc. (WJE) to
devise a plan to increase the number of parking stalls. We had been involved with a
similar project in which we considered adding parking on the garage roof and
believed that such an approach would be feasible in this case.
The roof deck of the garage serves as recreational space for tenants, with a
swimming pool and cabanas on the center section and tennis courts on the south wing
(Figure 1). The east wing had shuffleboards and playground equipment and was
relatively underused. This, we believed, was an appropriate place to add parking
stalls. However, the perimeter of the garage is at or near the property line, so we
couldn’t build a ramp next to the garage.

Figure 1 –The ramp was constructed at the south end of the center garage section.

We studied different ramp options, considering factors such as cost, traffic flow,
and the effect on existing parking, and concluded that the best place for the new ramp
was directly above an existing ramp, which links the first and second levels of the
garage (Figure 2). This approach would require demolition of a section of the post-
tensioned roof deck directly above the ramp. Complicating this demolition and the

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construction of the new ramp was the requirement that the parking garage remain in
operation throughout the project.

Figure 2 – The new roof-deck ramp was built directly above an existing ramp that links the
first and second levels of the garage.

The project was completed successfully through excellent cooperation and

contributions by WJE, general contractor Monson Nicholas Inc., and post-tensioning
subcontractor DSI Inc. For example, Monson Nicholas recommended building a
portion of the new ramp before demolishing the roof slab. This not only saved time
and money, it also created a platform on which to construct shoring and catch falling
debris from the demolition phase. In addition, DSI Inc. proposed detensioning and
restressing the roof-slab tendons in three phases. This eliminated the need to shore
the entire roof slab, avoided possible traffic problems in the garage, and reduced the
time and cost of construction.

2. STRUCTURAL ANALYSIS FINDS ROOF PARKING FEASIBLE

Built in 1969, the parking garage originally had two parking levels. The first floor
is a concrete slab on grade. The second-level parking deck and the roof slab are two-
way post-tensioned concrete flat slabs. Expansion joints divide the garage into three
sections: a 45.5 x 86.6 m center section where the main garage entrance is located, a
29 x 73.2 m east wing, and a 30.5 x 47 foot south wing (see Figure 1).
We reviewed the load-carrying capacity of the roof slab, supporting columns and
foundation to determine if the structure could safely support the additional cars.
Because shop drawings showing the slab tendons were not available, we determined

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

the tendon size and spacing with rebar locators and exploratory openings and by
finding tendon anchors on the edge of the structure. The post-tensioning tendons,
consisting of 1/2 inch (12 mm) diameter strands bundled in groups of three or four,
were spaced about 3 feet apart (90 cm) along the length of the structure (Figure 3).
The roof slab, columns and footings were found to have the code-required strength to
support the cars.

Figure 3 – Typical post-tensioning tendons consisted of 1/2 inch diameter strands bundled in
groups of three or four along the length of the structure

3. RAMP DESIGN AND CONSTRUCTION: PHASE I

We designed the new ramp as a concrete slab conventionally reinforced (one way)
with epoxy-coated rebar. The ramp is 6.50 m wide and 18.75 m long. Edge beams
that also form the ramp curbs and span between existing reinforced concrete columns,
which are spaced about 6.1 m apart, support the ramp slab.
The connection of the new edge beams to the existing concrete columns is based
on the shear-friction provisions of the ACI 318 building code. Therefore, the column
face was roughened and cleaned where it would be in contact with the new beam
concrete, and the beam reinforcing was epoxy-anchored into drilled holes in the
column concrete (Figure 4).

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Figure 4 –The connection of the new edge beams to the existing concrete columns is based on
the shear-friction provisions of the ACI building code.

A unique aspect of the construction was that contractor built the new ramp in two
phases, with the lower portion of the ramp being constructed before the roof section
was removed (Figure 5). This allowed the contractor to begin the project earlier in
the construction season and provided a platform from which to shore the roof deck
during demolition.

Figure 5 – Workers place reinforcement during the first phase of ramp construction

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

The formwork for the new ramp required special shoring to permit the ramp below
to remain open during construction. Closely spaced beams spanned across the
existing ramp, supported on both sides by braced shoring frames (Figure 6). Plywood
on top of the beams not only served as forms for the new ramp concrete but also
collected debris from the demolition of the roof deck in the upper part of the ramp.

Figure 6 – The formwork for the new ramp required special shoring to permit the ramp below
to remain open during construction.

4. POST-TENSIONING MODIFICATIONS
The initial phase of demolition required the removal of 10 pool cabanas that rested
on the section of the roof deck to be removed.
Creating the roof opening required detensioning and cutting the roof-deck tendons
and reanchoring them along the edge of the opening. The original design required
installing temporary intermediate anchors at each tendon before detensioning all the
tendons at the edges of the opening for the new ramp. This would have required
costly and disruptive shoring beneath the entire roof slab. At DSI’s suggestion, we
analyzed the roof-slab capacity and found that the tendons could be detensioned and
reanchored in three phases. In each phase, every third tendon bundle would be
detensioned, new tendon end anchorages installed at the appropriate location along
the new slab edge, and the tendons retensioned once the new concrete in the
anchorage zone had achieved sufficient strength (Figure 7). This approach eliminated
the need to shore the roof slab except around the section to be removed. To speed the
project, high-early-strength concrete was used to cast the new anchorage zones,
allowing the tendons to be retensioned two or three days after concrete placement.

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Figure 7 – Workers construct new post-tensioning tendon end anchors at their new locations
along the edge of the roof deck opening.

One difficulty we encountered during the project was the discovery of a few failed
tendons in the portion of the roof to remain. This required spliced repairs of the
tendons before restressing.

5. ROOF DEMOLITION
Once the tendons were reanchored, workers began demolishing the roof slab.
After chipping out the slab edges with hand-held chipping hammers, workers used a
mounted hydraulic breaker on a skid-steer loader to break up the concrete in the areas
of removal. Once broken up, the loose material, now supported by the protective
formwork beneath the removal areas, was scooped up with the skid-steer and dropped
down a debris chute leading to a dumpster parked streetside. After demolition was
completed, Phase I ramp was constructed (see Figure 8).

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Figure 8 – Completed Phase I ramp

6. RAMP CONSTRUCTION: PHASE II

Once the opening in the roof slab was made, workers formed and cast the
remainder of the new ramp slab. They then formed and cast a new concrete parapet
wall along the edges of the ramp as well as barrier walls along the perimeter of the
new roof parking deck. In addition to providing obvious safety benefits, the walls
also made the new parking area less visible from the pool and surrounding buildings.
Because the deck would be exposed to deicing salts, we specified two coats of a
penetrating silane sealer for the roof and ramp to reduce permeability. Additional
features of the design for the new ramp included:
 Supplemental light poles in the new parking area
 Additional light fixtures on the sidewalls and underside of the new ramp
 Supplemental drains on the roof deck
 Replacement of the existing roof deck expansion-joint seal with a new one
suitable for car traffic

7. CONCLUSION
The project resulted in the addition of 70 parking spaces at a cost of $400,000.
Based on the cost of car space rentals in the area, the project created an additional
value to the owner of about $1 million. Construction began in April 1997 and was
substantially complete by 1997.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
Predrag L. POPOVIC

EVALUATION AND REPAIR OF PARTIALLY COLLAPSED HIGH

RISE BUILDING UNDER CONSTRUCTION
Abstract: A partial collapse of the 13th floor of a building under construction due to fire presented
significant challenges to evaluate the safety of the remaining structure and to remove the debris. Quick
action by structural engineers and contractor’s personnel resulted in safe removal of collapsed slabs and
continued construction of the upper floors of the building to meet the original construction schedule.
Fire damaged areas of the structure were repaired without delaying the construction.

Кey words: fire, high rise building, collapse, repair.

ISPITIVANJE I SANACIJA DELIMIČNO SRUŠENE VIŠESPRATNE

ZGRADE U TOKU GRADNJE
Rezime: Kolaps 13-og sprata višespratne zgrade u toku gradnje usled požara, je zahtevao ispitivanje
sigurnosti ostalih delova zgrade i uklanjanje srušenog materijala. Brza akcija inženjera i izvodjača je
dovela do rasčiščavanja srušenih betonskih ploča i nastavljanja gradnje. Oštećeni delovi zgrade su
sanirani u isto vreme dok je gradnja zgrade napredovala, čime je omogućeno da bude završena u
planiranom roku.

Ključne reči: požar, višespratna zgrada, rušenje, sanacija.

Vice President and Senior Principal, Wiss, Janney, Elstner Associates, Inc., Northbrook, Illinois,
ppopovic@wje.com

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1. DESCRIPTION OF STRUCTURE
A 20-story office building under construction had a structural system which
consisted of post-tensioned concrete flat slab supported by reinforced concrete
columns and shear walls. The construction sequence required that the formwork for
each new concrete floor be supported by timber shores from the previously completed
concrete floor. To meet the aggressive construction schedule, the weight of the newly
cast concrete floor was distributed by timber reshores to three lower floors. After the
new concrete floor is cast and its concrete reached required strength, post-tensioning
tendons previously placed within the slab would be tensioned and the new slab floor
would have its full load-bearing capacity. Until this post-tensioning force was
introduced into the concrete floor slab, the weight of the concrete floor had to be
supported by shoring from the lower, already completed floors. The only reinforcing
present, prior to post-tensioning, was a few reinforcing bars over the columns to
control concrete cracking in the completed slab.
To allow for continuous construction through the winter, with temperatures as low
as -30°C, gas heaters were used to help cure the newly cast concrete slab at one-half
of the 13th floor. On 5 January, one of the gas heaters exploded and timber shoring
and formwork caught on fire, as seen in Figure 1. At that point, the 13th floor
concrete slab was only one day old and did not have sufficient strength to carry its
own weight without being supported by shoring. The shoring and formwork quickly
burned and the 13th floor slab collapsed on top of the 12th floor slab. Figure 2 is a
view of the collapsed slab.

Figure 1- Top of building on fire Figure 2 - Collapsed portion of the 13th floor

2. CONDITION OF STRUCTURE
As soon as the firefighters extinguished the fire, the investigation of the building
began. The first concern was the safety of the remaining portion of the building; with
the 13th floor slab debris overloading the 12th floor slab, which was at that point in
time only one week old. In order to access the top of the building safely, a large

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construction crane was used to bring the engineers to the top of the building. A view
of the collapsed 13th floor slab from the crane is shown in Figure 3.
Large sections of concrete slabs were lying on top of the 12th floor and were
partially suspended from the tops of columns and from the shear walls in the core of
the building. The tops of the columns had punched through the slab and the
reinforcing shear heads at the tops of the columns were visible as seen in Figure 4.
Post-tensioning cables over the tops of the columns were tight and they were able to
transfer some of the weight of collapsed slabs to the columns, relieving the load from
the 12th floor slab. Visual inspection of the underside of the 12th floor slab revealed
numerous cracks caused by the weight and the impact of the 13th floor debris.
However, the timber reshores which extended to the three floors below, were able to
distribute the weight of the debris to several floors and prevent the progressive
collapse of the whole building.

Figure 3 - Collapsed concrete slabs Figure 4 - Shear heads on top of columns

Figure 5 - Extensively damaged column Figure 6 - Minor damage to the top of column

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Concrete columns in the collapsed portion of the 13th floor were badly fire
damaged (Figure 5), while columns in the remaining area of the same floor had only
minor damage near the top (Figure 6). The difference in damage was due to the fact
that in the collapsed area, the fire was confined by the presence of concrete slab
before it collapsed and that the columns were exposed to fire for a longer period of
time than in the other area where only the formwork was present. Compressive
strength testing and petrographic examination of concrete samples taken from these
columns confirmed the findings of the visual examination.
Portions of shear walls exposed to fire suffered significant surface damage (Figure
7). The depth of spalled concrete was in a range of 50 mm. The same walls on the
side where the 13th floor slab was not present had only minor concrete damage near
the top of the wall. The top of the 12th floor slab received only minor damage
(Figure 8) due to the fact that the fire load of burning shoring and formwork on the
top of the 12th floor was directed upward. The damage consisted of surface spalling
in a number of areas.

Figure 7 - Fire damaged shear wall Figure 8 - Minor damage to slab below

3. TESTING OF POST-TENSIONED TENDONS

The main concern in evaluating the 12th floor slab after the fire was the condition
and capacity of post-tensioning tendons in the slab. The post-tensioned cables subject
to heating could lose 40 percent of the force at temperatures of about 400°C and up to
90 percent at temperatures of 550°C. The temperature of the concrete surrounding
the post-tensioning tendon during the fire was not known. However, the upward
direction of the heat generated by the burning shoring and the formwork on top of the
12th floor slab indicated that the post-tensioning cables were not subjected to very
high temperatures. The best way to determine the actual remaining force in post-
tensioning tendons was to test a certain number of tendons and measure the remaining
force.
The testing of the 12th floor cables was made easier due to the fact that slab was
only about a week old at the time of collapse and that the ends of the cables along the
perimeter of the building were not yet cut off. The challenge was to come up with a
way to pull individual seven-wire strand and measure the force at the point when the
wedges in cable anchors lift off their position. A hydraulic jack was supplemented

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with a dial gage which measured the displacement of wedges and an additional
acoustical device was connected to the dial gage to give a loud noise signal when the
wedges are unseated. Figure 9 is an overall view of this instrumentation set-up and
Figure 10 is a close-up view of dial gage and hydraulic jack.

Figure 9 - Lift off test apparatus Figure 10 - Dial gage on hydraulic jack

Using this system, about 10 post-tensioning cables along each side of the building
were pulled and the wedges were lifted off their seats. The measured remaining force
was very close to the original jacking force and the conclusion was that if there was
any loss of force, it was insignificant.

4. REMOVAL OF DEBRIS
The most challenging task after the fire was how to safely remove the debris
without damaging this building or the surrounding buildings. The first step was to
determine if there was damage to the top of a steel tower for the material handling
elevator along the side of the building in the area of where fire occurred. The paint
on the surface of the steel tower changed color due to the heat of the fire. After
review and testing, the structure of this elevator was determined to be safe for
continuous use and this elevator was continuously used throughout the investigation
for removal of debris.
Portions of collapsed slabs were hung from the tops of columns along one side of
the building, as seen in Figure 11. The cables hanging over the columns acted as a
string and large pieces of concrete slabs were like beads in a giant necklace. This was
an unstable configuration with a potential that one or more concrete pieces could pull
the rest of the debris down the side of the building and fall on a lower adjacent
building. Trying to remove one piece at a time could have caused all of them to
collapse. To make the situation more difficult, some of the pieces of the collapsed
slab were projecting beyond the building edge.
Each of the pieces of concrete was individually wrapped with steel cables and
special metal hooks were attached to the edges of pieces which were projecting
beyond the edge of the building (Figure 12). Then a cable for each piece was

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connected with a chain and a come-a-long to the base of an interior column to be used
to pull all the pieces simultaneously inside the perimeter of the building.

Figure 11 - Slabs hung along building edge

Figure 12 - Securing individual slab pieces Figure 13 - Cutting the cable to lower slabs

This work was scheduled during a night when the street below could be blocked
and the adjacent lower building was emptied. As the pieces were pulled toward the
inside of the building, cables form which they were hung were cut off to allow the
pieces to be lowered to the top of the 12th floor slab (Figure 13). This operation was
completed safely during the night and the pieces were cut and removed the next day.
Extensively damaged columns were removed (Figure 14) as well as the pieces hung
form the shear walls (Figure 15).

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Figure 14 - Removal of damaged column Figure 15 - Removal of slabs at shear wall

5. REPAIR OF STRUCTURE
Schedule of construction for this building had a major impact on timing of the
repairs. The building had to be completed on schedule and further delays due to
repairing the building immediately after the fire would have resulted in significant
losses of time and money. Also, the temperatures in January, when the collapse
occurred, and in February when the debris was removed and the investigation was
completed, were often below -10°C and were not the best for concrete repair.

Figure 16 - Chipped out and repaired shear wall

After the investigation was completed, a decision was made that the construction
of upper floors proceed and the required repairs be performed in Spring when the
temperature is higher. The fire damaged portions of shear walls were chipped out and

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the concrete surface and reinforcing steel were sandblasted. Then, a new 100 mm
thick layer of concrete was cast on the shear wall face. This wall is shown in Figure
16. The spalled areas of 12th floor concrete slabs were very shallow and they were
sandblasted and patched with an epoxy grout. Since they were inside the completed
building with a stable temperature, there was no concern about potential difference in
temperature moduli between concrete and epoxy grout.

6. CONCLUSIONS
Total collapse of the 13th floor slab due to the fire could have led to the
progressive collapse of the whole building. The presence of the reshores in the three
lower floors helped distribute the weight of the collapsed slab and prevented the total
collapse. The immediate and quick action by evaluating structural engineers and
contractor’s personnel resulted in removal of unstable debris from the top of the
building and in determination that the remaining parts of the structure were
structurally sound and that only minor repairs were necessary to the fire damaged
concrete. The decision to proceed with the construction of the upper floors and to
perform the repairs later helped maintain the original building construction schedule.
All debris removal and structural evaluation work was performed under windy
conditions on the top of the building with the temperatures below -10°C.

[321]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
1
Vlastimir RADONJANIN
Dušan KOVAĈEVIĆ2
Mirjana MALEŠEV3
Slobodan ŠUPIĆ4
Ivan LUKIĆ5

TESTING THE INFLUENCE OF DYNAMIC LOADS ON THE

STRUCTURAL ELEMENTS OF PETROVARADIN FORTRESS
Abstract: Petrovaradin Fortress belongs to the category of significant cultural and historical buildings of
fortification engineering, with expressed architectural, artistic and environmental values and it was
established for the cultural monument in 1948. For years, a number of different events are held at the
fortress, the necessary equipment was delivered and installed and various programs were performed. The
effect of dynamic loads on the elements of the fortress during the festival "EXIT" was investigated, in
order to obtain necessary information about the real condition of structural and non-structural fortress
assemblies and determine the possible degradation of their bearing capacity, rigidity and usability due to
the specific load caused by different events. The paper presents the results of the tests.
Кey words: fortress, dynamic load, degradation, load, capacity, testing

ISPITIVANJE UTICAJA DINAMIČKIH OPTEREĆENJA NA

KONSTRUKCIJSKE SKLOPOVE PETROVARADINSKE TVRĐAVE
Rezime: Petrovaradinska tvrĊava spada u kategoriju znaĉajnih kulturno-istorijskih objekata
fortifikacijskog graditelјstva, izraženih arhitektonskih i likovno-ambijentalnih vrednosti, na osnovu ĉega
je 1948. god. utvrĊena za spomenik kulture. Godinama unazad broj razliĉitih manifestacija se održava na
prostoru tvrĊave, doprema se i montira neophodna oprema i izvode se razliĉiti programi. U cilјu zaštite i
oĉuvanja, izvršeno je ispitivanje uticaja dinamiĉkih opterećenja na elemente Petrovaradinske tvrĊave
tokom festivala „EXIT“, kako bi se na osnovu rezultata ispitivanja dobile potrebne informacije o
realnom stanju konstrukcijskih i nekonstrukcijskih sklopova tvrĊave i utvrdila eventualna degradacija
njihove nosivosti, krutosti i upotreblјivosti usled konkretnih opterećenja izazvanih održavanjem
manifestacija. U radu su prezentovani rezultati predmetnog ispitivanja.
Ključne reči: tvrĊava, dinamiĉko opterećenje, degradacija, nosivost, ispitivanje

1
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: radonv@uns.ac.rs
2
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: dusan@uns.ac.rs
3
PhD, Full Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: miram@uns.ac.rs
4
Ass. MSc CE, University of Novi Sad, Faculty of Technical Sciences, e-mail: ssupic@uns.ac.rs
5
PhD, Assistant Professor, University of Novi Sad, Faculty of Technical Sciences, e-mail: lookic@uns.ac.rs

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1. INTRODUCTION
Petrovaradin Fortress belongs to the category of significant cultural and historical
buildings of fortification engineering, with expressed architectural, artistic and
environmental values, with special significance in the cultural history and it was
established for a cultural monument in 1948. The aim of the work is to determine the
real condition of structural assemblies of Petrovaradin Fortress in the period of
exploitation of the complex during manifestation.

Figure 1 – Petrovaradin Fortress

For years, the number of different events (cultural, musical, sports, etc.), which are
held on the territory of the fortress, has been increased. For the purpose of
maintenance of manifestation (EXIT, Tamburica fest, Baby EXIT, Days Brazil, Days
NIS, individual concerts of popular music, etc.), the necessary equipment is delivered
and installed on the territory of fortress and the various programs are performed and
attended by a large number of visitors. Testing of impacts that accompany these
events (music, noise from the audience, transportation and disposal, as well as
assembly and disassembly of equipment) on the structural elements of the fortress
was never investigated, which for years, without any argument, leaves room for
debate on the justification for using the fortress for such purposes [1].
In order to protect and preserve this unique monument, the effect of dynamic loads
on the elements of the fortress, present in the exploitation area of the complex, has
been investigated in order to obtain necessary information about the real condition of
structural and non-structural assemblies of fortress and determine the possible
degradation of their bearing capacity, rigidity and usability due to the specific load
caused by maintenance events. To examine the impact of vibration, the largest
musical event held in the territory of the fortress - EXIT festival was selected (the
time of the festival "EXIT" 2015 was 9-12. of July 2015). As this manifestation takes
place on more than 20 stages located throughout the complex, typical spots were

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selected, one in the upper fortress and one in HornVerk, which are most exposed to
vibrations, and on which the necessary research would be carried out.
In order to determine the condition of selected structural assemblies of
Petrovaradin Fortress in the period of the exploitation during the festival "EXIT", and
the impact of similar events on the dynamic characteristics and possible occurrence of
damages of masonry structures within the fortress, following activities were carried
out:
 a detailed visual inspection of characteristic masonry structures, with
registration and a description of the observed damages and
 measurement of horizontal and vertical vibrations at 6 measuring points in 3
phases of exploitation.
A detailed visual inspection of the structural and non-structural assemblies on 6
selected locations (where the vibration impact was recorded), with the description of
the registered damages, was carried out prior to the festival "EXIT" and after
completion.
The paper presents a "recorded" state of examined masonry structures, the results
of vibration measurements and analysis of the behavior of selected elements of
masonry elementts of the fortress due to dynamic effects.

2. ASSESSMENT OF THE STRUCTURAL ELEMENTS OF

PETROVARADIN FORTRESS BEFORE AND AFTER THE
MAINTENANCE OF THE FESTIVAL "EXIT"
2.1. UPPER FORTRESS
On the basis of detailed visual inspection of the masonry elements, following
damages were registered:
 longitudinal horizontal cracks along the facade in place where horizontal
insulation was subsequently derived (damage B, Figure 2),
 cracks in the upper parts of the facade, around the openings, extending to the
edge of the roof (Figures 3-4),
 net-like fissures on mortar layer (Figure 5),
 rinsing of mortar joints and brick falling out (Figure 6),
 cracks through mortar joints and bricks (Figure 6),
 ingrown vegetation (Figure 7).
Following figures illustrate listed damages.

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Figure 2 - Scheme with damages on the south-east facade of the museum Arsenal

Figure 3 - Cracks above the door (extending to Figure 4 - Cracks around windows,
the window) extending to the edge of the roof

Figure 5 – Net-like fissures in the mortar layer, horizontal crack in place where horizontal
insulation was subsequently derived

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Figure 7 - The subsequent joints sealing

with mortar, ingrown vegetation

Figure 6 – Rinsing of joints, cracks through Figure 8 - Subsequent filling of joints with
mortar joints and bricks mortar, broken bricks along the edge of the
wall

2.2. "HORNVERK" – MASONRY STRUCTURES

Figures 10-13 present damages of masonry structures, whose general appearance
is shown in Figure 9.

Figure 9 - The appearance of masonry structure

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Figure 11 - Whole bricks falling out,

ingrown vegetation

Figure 10 - Spalling and brick falling out Figure 12 - Spalling of the surface brick
from the wall layer
After the completion of the festival, a second detailed visual inspection of
characteristic masonry structures has been carried out. The analysis of data revealed
that there has not been intensification nor propagation of registered damages on the
measuring spots during the festival. Therefore, negative influence of the
manifestation on the deterioration of the structures on the Fortress has not been
recorded.

3. VIBRATION MEASUREMENTS BEFORE, DURING AND AFTER THE

FESTIVAL"EXIT"
Vibration measurement was carried out in three characteristic phases of
exploitation of land and structures of the Petrovaradin Fortress: before, during and
after the festival "EXIT". It is enough representative for objective insight into the
impact of dynamic loads on the structural integrity and performance of masonry
structures of this complex, especially if the probable conditions of the largest and
most unfavorable dynamic effects are taken into account. The measurement results
are given in Table 1 as the minimum and maximum values of vibration velocity.

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Table 1 - Minimum and maximum horizontal and vertical vibrations in [mm/s] at measuring
points 1-6, before, during and after "EXIT" festival
Measuring The before "EXIT" during "EXIT" after "EXIT"
spot direction
↔ -18.9 16.2 -8.3 6.4 -8.9 8.1
1
↕ -2.6 0.2 -2.4 0.1 -2.5 -0.2
↔ -9.2 6.8 -8.5 6.2 -9.6 10.6
2
↕ -2.6 0.5 -2.1 -0.1 -2.4 0.4
↔ -8.3 5.2 -8.2 8 -18.6 16.4
3
↕ -2.4 0.5 -2.4 0.2 -2.9 0.7
↔ -24.8 18.8 -8.8 6.2 -11.6 11.1
4
↕ -2.5 0.4 -2.2 0 -3.5 0.5
↔ -7.8 6.7 -14.6 14.8 -11.8 7.7
5
↕ -2.6 0.4 -2.8 1 -3.1 0.4
↔ -20.2 19.1 -16.9 14.5 -22.2 15.6
6
↕ -2.5 2.1 -2.2 0.9 -2.8 0.5

Based on the results of horizontal and vertical vibration velocity, the following can
be concluded:
 Registered extreme vibration velocity values do not reflect typical behavior for
the dynamic effects of the observed structural assemblies induced by human
activities, but due to other, probably "environmental" causes, and these values
won't be considered in accordance with the provisions of DIN 4150-3,
 In all the observed structural assemblies at all measuring spots, several times
higher values of horizontal vibration velocity were registered, relative to the
corresponding vertical velocity vibration,
 Vibration of the observed structural assemblies at all measuring spots have
similar values with dominant frequency (fB≈1.8Hz - 2.5 Hz), so it can be
assumed that the dominant cause of vibration is not the result of events at the
"EXIT", especially if the registered frequency "modulation" (fM≈100Hz) is
taken into account,
 Vibrations, measured before and during the festival "EXIT", have similar
values, ie. differences can be considered as random, which corresponds to the
hypothesis on the dominant cause of vibration that is not a consequence of the
events at the "EXIT",
 Vibrations, measured after the manifestation "EXIT" on all structural
components and all measuring spots generally have higher velocity than
vibrations measured before and during "EXIT", which corresponds to the
hypothesis on the dominant cause of the vibration that is not a consequence of
the events at the event "EXIT",
 Exeption from this regularity is a significant difference in the rate of vibration
between the stage prior to and during "EXIT" at measuring spot 5 and refers to

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the registered vertical vibrations, but this difference is significantly below the
permissible limits by DIN 4150-3,
 Due to the nature and size of registered vibration velocities, there is a need to
establish a permanent system of monitoring of the dynamic behavior of the
characteristic structural assemblies of Petrovaradin Fortress in order to
determine the real effects that significantly affect its structural usability.

4. CONCLUSION
Registered damages were largely caused by the destructive environmental effects
(rain, snow, frost), as well as due to lack of maintenance in the past. Currently,
damages do not threaten the capacity and stability of the examined masonry
structures, but their durability is compromised.
Comparing the condition of the structures before and after "EXIT", it can be
concluded that there was no intensification nor propagation of registered damages
during the festival. Therefore, negative influence of the manifestation on the
deterioration of the structures on the fortress has not been recorded.
In order to prevent further deterioration and progressive increase of the damages, it
is necessary to induct the maintenance program, under which "washed" mortar joints
would be filled, parts of missing bricks rebuilt, ingrown vegetation removed, cracks
injected etc.
Based on the analysis of vibration measurements, it can be concluded that the
dynamic behavior of the observed structural assemblies does not reflect the nature of
the events at the "EXIT", but other causes, so introducing a system of permanent
monitoring could be the long-term solution to the structural safety of masonry
structures of Petrovaradin Fortress.

ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

5. REFERENCES
[1] http://www.zzskgns.rs/wp-content/uploads/2015/06/20150617141854.pdf,
downloaded on 07. July, 2015.

[329]
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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.059
Dalibor SEKULIĆ

ESTIMATION OF THE STATE OF RC STRUCTURES BY THE

IMPACT-ECHO METHOD USING ADVANCED ANALYSIS
Abstract: Deterioration of Reinforced Concrete structures is a serious problem worldwide. In order to
assess the condition of RC structures it is necessary to implement reliable and efficient non-destructive
test methods. "Impact-echo" is an acoustic method which utilizes reflections of transient elastic waves
from the damaged areas and boundaries of structural element to assess its condition. The paper presents
examples of In-situ tests performed on actual structures, with the application of advanced signal analysis.
It is shown that damages is determined with greater reliability than by the commonly used Fourier
transform.

Кey words: Reinforced concrete structures, condition assessment, NDT methods, Signal analysis

PROCJENA STANJA AB KONSTRUKCIJA IMPACT-ECHO

METODOM KORIŠTENJEM NAPREDNE ANALIZE
Rezime: Propadanje armiranobetonskih konstrukcija danas predstavlja ozbiljan problem u cijelom
svijetu. Kako bi se ocijenilo stanje armiranobetonskih konstrukcija neophodno je upotrebljavati
pouzdane i efikasne nerazorne metode ispitivanja. "Impact-echo" je akustična metoda koja koristi
refleksije elastičnih valova na oštećenim područjima i rubovima elementa konstrukcije kako bi se
ocijenilo njeno stanje. Rad prikazuje primjere terenskih ispitivanja, gdje su korištene napredne metode
analize signala. Prikazano je da su oštećenja određena s većom pouzdanosti nego uobičajeno korištenom
Fourierovom transformacijom

Ključne reči: armiranobetonske konstrukcije, ocjena stanja, nerazorne metode, analiza signala

Ph.D., Institut IGH d.d., Janka Rakuše 1, 10000 Zagreb, dalibor.sekulic@igh.hr

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1. INTRODUCTION
It is known that Impact–echo test method has certain limitations in respect to size
and depth of damages that can be detected [1, 2], but there are no well-established
criteria for the quantification of detection limits. Previous research is mainly based on
numerical modelling [3] and it is found a limited number of experimental works
involved in detection possibilities of IE method.
In this work, based on measurements performed on experimental reinforced
concrete field, detection limits of one improved IE method are determined. Impacts of
test sphere are generated automatically, by use of electro-mechanical device, leading
to reproducible contact time and force, therefore to better test results. Test results are
analysed by the use of autoregressive method, rather than by Fourier transform. Also
detection threshold is obtained experimentally which insure detection of damages
with 95% probability.
1.1. Impact echo test method
IE method operate with elastic waves of frequencies from about 2 kHz up to 80
kHz, which are introduced into material mechanically, by the low energy elastic
impact of small steel ball, after that a dynamical response to is measured by the
accelerometer. Response to applied impact is successive reflections of elastic waves
from boundary areas or from damages of structural element [4], as shown in Figure 1

Figure 1 (a) IE method principle (b) spectrum calculated by FFT method

Measured time dependent signal are converted into frequency domain by the Fast
Fourier transform (FFT). Figure 1(b) shows a typical spectrum obtained by the FFT
analysis of measured signal, where three dominant frequency peaks are visible. Peak
at the frequency fT appears as result of reflections of elastic waves from the opposite
surface of the structural element, peak at the frequency fD is result of reflections from
the damage and peak at frequency fs is result of flexural vibrations of concrete layer
above the damage. Frequency fD is related with the damage depth, by the equation (1)
[4].
v
D P (1)
2 fD
Where D = damage depth, vP = longitudinal wave velocity, fD = peak frequency.

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At equivalent way, from the frequency maximum fT, a thickness of structural

element T, can be calculated.

2. SIGNAL ANALYSIS METHODS

For signal analysis Fast Fourier transform (FFT) is standard used method to
convert signal from time to frequency domain. One of disadvantages of the FFT
method is that Fourier coefficients which specified spectrum represent averaged
spectral amplitudes during the overall duration of signal, so information about the
time in which particular signal components appear is lost.
FFT method is appropriate for analysis of stationary signals, where particular
frequency components exist during the overall time of signal. However, as IE signal
is no stationary, by knowing of the time period in which particular component of
signal exists can simplify interpretation of test results [2].
2.1. Yule-Walker autoregressive method
In this work for signal analysis Yule-Walker autoregressive method is used. Yule-
Walker method is based on the assumption of the correlation between the part of
signal at the time t = τ and the part of signal at the time t = - τ (autocorrelation) [5].
Autocorrelation is described by the equation:
Rˆ ff ( )  f * ( )  f ( ) (2)

Where R̂ ff ( τ ) is auto covariant function and right side of the equation is

convolution of complex conjugated signal at the time -τ with the signal at the time τ.
In the case of real signal f * ( ) = f ( ) .
For the discrete real signal auto covariant function is given by the expression:
1 N
R   yt  yt 
N t  1
(3)

Where is n filter order (length).

Autoregressive model from the obtained auto regression parameters ai can be
written as:
p
yt   ai yt i
i 1 (4)
From this expression, each signal pattern can be determined on the basis of
previous signal patterns.
Benefits of the use of this alternative spectral analysis method are:
a) Noise decrease – as a noise is randomly process, by the summation of more
spectrums, amplitudes coming from the noise are cancelled;

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b) Spectrum ”softening” - By the summation of more spectrums, frequency

components which are present into all summed spectrums are amplified. For the IE
method, there are resonant frequencies coming from the reflections of elastic waves
and from the flexural vibrations. Waves which appear only in the particular part of
spectrum, such as Rayleigh surface waves will be decreased.
Disadvantages of method are decrease of frequency resolution and loss of some
signals which still can be of interest.
2.2. Detection threshold
Detection threshold is determined from the set of 30 measurements conducted at
the concrete plate for which is known that it is no damaged [4]. Measurements at
different positions include influences of measurement equipment, concrete non
homogeneity and boundary effects to noise level.
As concrete was no damaged at measured spectrums only frequency peaks of
flexural vibrations at low frequency, fSP and responses from the opposite surface of
tested plate, fT was recognised. All other visible frequency peaks are characterised as
a noise. Figure 2 shows intensity of peaks of noise as a noise depending on frequency.
It is obviously that intensity of noise peaks, IN decrease as frequency f increase.
Regression analysis gives best – fit function of hyperbolic shape:
IN( f ) = A / f + B, (5)
7

6
Average noise intensity
5
Intenzitet šuma

4
Detection treshold

0
10 20 30 40 50 60 70 80
f (kHz)

Figure 2. Average noise intensity for 30 measurements, and detection threshold for Yule-
Walker analysis method

Detection threshold is determined as a limit value of noise intensity for 95 %

probability. (Figure 2).
Figure 3 shows one of measuring results analysed by the Yule-Walker method
with indicated average noise level and detection threshold. Peaks above detection
threshold present real damages which is determined with 95% probability and peaks
below detection limit originated from noise. Detection threshold setting at the lower
level would result that signal originated from the noise is interpreted as a response
from the damage.

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Besides that, the detection threshold setting to a higher level would lead to a
reduction of the detection capabilities of IE methods, because it would detect only
defects which give stronger responses.
18

16
fD
14

12
fT
Average noise
Intenzitet

10 level Detection
8 treshold
6

2 1,96 
0
0 20 40 60 80 100
f (KHz)

Figure 3 Example for detection threshold determination for Yule-Walker method of signal
analysis

3. IN-SITU MEASUREMENTS
Established detection threshold is used for analysis of in-situ measurement results.

Figure 4 Damaged foundation of heavy duty fan in the Cement plant

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Figure 4 shows damaged foundation of heavy duty fan in the Cement plant.
Vibrations of unbalanced fan caused bending stresses in RC foundations which cause
appearance of transverse cracks. Impact echo method is used to determine real extent
of damages. Measurements are conducted at the side and top surfaces at the 10x10 cm
measurement grid as shown in Figure 4. Visual assessment shows several open cracks
at side surfaces.
Figure 5(a) shows measurement signal analysed by the Fast Fourier transform
method, where we can see many frequency peaks and it is hard to make decision
which ones originated from cracks. By the signal analysis by the use of Yule Walker
autoregressive method some peaks are separated as shown in figure 5(b). Peaks which
are above the previously established detection limit represent transverse cracks.

(a) (b)

Figure 5 One Example of obtained measurement results analysed by (a) FFT method, (b) Yule
Walker method
Figure 6 show measurement results in B-scan presentation (frequency peaks as a
function of measurement position, for a) standard FFT analysis, b) Yule-Walker
analysis and c) Yule-Walker analysis included detection threshold application.

(a) (b)

(c)

Figure 6 Measurement results for one line analysed by (a) FFT method, (b) Yule Walker
method, (c) Yule Walker method with detection threshold application

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Figure 6 (a) shows many responses and it is very difficult to determine which ones
originated from cracks. By the Yule Walker analysis (Fig) less number of responses is
obtained and with the detection threshold application only responses that originated
from cracks are visible. By the use of equation (1) depths of cracks are calculated.
Depths of founded cracks are in agreement with visually indicated cracks, and also
some non-visible cracks are also detected. Results prove assumption that cracks is
caused by flexural vibrations of foundation elements.

4. MEASUREMENTS ON THE PLATE WITH KNOWN VOID

Measurements on the plate with embedded “realistic damage” made from
polystyrene are conducted by the use of measurement mesh with spacing of 5 cm.
Measured signals are transformed into frequency domain by the Yule – Walker
autoregressive method, described in the clause 2.1.. A detection threshold for 95 %
probability of detection is used, according with the description in the clause 2.2.
Examples of test results presentations as (a) B-scan, (b) C-scan and (d) 4 dimensional
are shown in Figure 7.

(
c)

Figure 7 Examples of test results presentation (a) B-scan, (b) C-scan, (d) 4 dimensional

5. CONCLUSION
Paper shows that use of advanced signal processing methods such as Yule-Walker
autoregressive autocorrelation method leads to better interpretation of measurement
results obtained by Impact – echo test method. By the detection threshold
introduction, a 95% probability of real damages detection is insured and detection of
concrete non-homogeneities (beside other influences) as damages is avoided.

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Based on these assumptions an example of in-situ tests is analysed. Results show

that all open cracks visible from the side of RC element is detected. Some cracks
which is not visible is detected too.
Measurement results of “realistic” damages are successfully presented as a B –
scan, C – scan and in a four dimensional view.
It can be concluded that processing of measurement signals by Yule - Walker
method and use of detection threshold leads to better interpretation of measurement
results.
Paper presents only some results of more extensive research [5], where also
frequencies and intensities of responses are detailed analysed, POD model for Impact
– echo method is established and research of possibility for non-contact detection of
elastic waves by the Laser Doppler vibrometer (LDV) is conducted.

REFERENCES
[1] Carino, N.J. (2001) “The Impact-Echo Method: An Overview”, ASCE
Proceedings of the 2001 Structures Congress & Exposition, May 21-23,
Washington, D.C., Am. Society of Civil Engineers, Peter C. Chang (ur), 18 p.
[2] Shokouhi P., Gucunski N., Maher A. (2006) “Applicability and Limitations of
Impact Echo in Bridge Deck Condition Monitoring” 12th European Meeting of
Environmental and Engineering Geophysics - Near Surface 2006, September 4,
Helsinki, Finland.
[3] Sansalone, M., and Carino, N. J. (1990), “Finite Element Studies of the Impact-
Echo Response ofLayered Plates Containing Flaws” International Advances in
Nondestructive Testing, 15th Ed. W. McGonnagle, Gordon & Breach Science
Publishers, New York, 313-336.
[4] Sekulić, D. (2011) „Detection of damages in reinforced structures by elastic
waves“, Doctoral Thesis, Civil Engineering Faculty, University in Zagreb,
Croatia.
[5] Özdemir, E. (2008) Super-resolution spectral estimation methods for buried and
through-the-wall object detection, MS thesis, Boğaziçi University.
[6] Ryden, H., Ronneteg, U. (2006) “POD (Probability of Detection) Evaluation of
NDT Techniques for Cu-Canisters for Risk Assessment of Nuclear Waste
Encapsulation”, ECNDT 2006, Berlin, September 25-29, 2006.

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DESIGN AND CONSTRUCTION OF BRIDGES
AND ROADS
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.2/.8+625.73
1
Doncho PARTOV
Dobromir DINEV2

DESIGN APPROACH AND CONSTRUCTION PROCESS OF THE

FIRST LARGE STEEL ORTHOTROPIC BRIDGE IN BULGARIA
Abstract: The most spectacular and large bridge in Bulgaria and one of the largest in South-East Europe
– Asparuhov bridge in Varna was put into operation at the beginning of September 1976. The total
length of the bridge is 2050 meters and includes: a middle part with three-span steel structure
(80.5+160+80.5 m) and the rest of the bridge is designed by prestressed concrete beams with length of
40 meters. The middle part is located above a ship canal that connects Varna Lake with Black Sea. The
bridge consists of two parallel parts which carry the traffic in two opposite directions. The steel structure
is designed as a three-span continuous beam with a box cross-section and an orthotropic deck. The paper
deals with the most important aspects which consider the design approach and the construction process
of the first large steel orthotropic bridge in Bulgaria.
Кey words: Orthotropic plate, construction methods, bulgarian bridge heritage.

PRISTUP PROJEKTOVANJU I PROCESU IZGRADNJE PRVOG

VELIKOG ČELIČNOG ORTOTROPNOG MOSTA U BUGARSKOJ
Rezime: N j pek k l niji i eliki mo g koj i jed n od n j e ih j goi očnoj E opi -
A p ho mo V ni p š en je d poče kom ep emb 1976. Uk pn d žin mo je 2050 me
i obuhvata: srednji deo - čeličn kon kcij i pon (80,5+160+80.5m) i o k mo , iz eden
od prethodno-napregnutih betonskih g ed d žinom od 0 me . ednji deo e n l zi izn d k n l
koji po ez je V n jeze o nim mo em. Mo e oji od d p leln del koj no e ob j
d p o n me . Čeličn kon kcij je p ojek o n k o kon in ln g ed ri raspona sa
k ij im p e ekom i o o opnom pločom. U d di k o ni n j žniji pek i koji zm j
p ojek o nje i p oce izg dnje p og elikog o o opnog čeličnog mo g koj.
Ključne reči: O o opn ploč , g Ďe in ke me ode, b g ko n leĎe - mostovi

1
P ofe o , Uni e i y of c l Enginee ing nd A chi ec e, V U“Ly ben K elo ”, lg i ,
e-mail: partov@vsu.bg
2
Assist. Professor, University of Architecture, Civil Engineering and Geodesy, Bulgaria,
e-mail: ddinev_fce@uacg.bg

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1. INTRODUCTION
In the early 1970s the construction of the West port of Varna and the increasing of
the industrial importance of the city demand to widen the existing canal which
connects the Varna Lake and Black Sea to accommodate the increased ship traffic.
The development of the city area leads to increased road traffic in direction Varna-
Bourgas, requires to construct of a motor highway that crosses the canal.
In 1967 – 1968 the government arranged the competition for the preliminary
design solution. The jury was leaded of the famous bridge engineers prof. F. Faltus
and prof. Juri Klimes from Civil Engineering Faculty at Czech Technical University
in Prague. The rest of the jury was prominent Bulgarian persons and experts. The
winning proposal was developed by the team of Dr. B. Bankov (1912 - 1992) and
suggests a large steel bridge with a total length of 2200 m and spans between 100 and
200 m. The other 11 proposals were included a detour road, a tunnel and even a ferry
[1]. In these years it was very difficult for the government to provide so large quantity
of high-strength steel. Because of this the bridge was designed as a combination of
following parts: the central part was a 3-span steel structure (80.5+160+80.5 m); the
approaches to the main bridge were made of 39 spans of 40.2 m of precast prestressed
concrete T-beams (fig.1)[9].
20250 20244 20100 20100 20100 32000 20100 20100
Ñåêöèÿ 5 Ñåêöèÿ 6
Ñåêöèÿ 4 20100 20100 Ñåêöèÿ 7
20100 4020 4020 4020 4020 4020 4020 4020 4020 4020 4020 19980
Ñåêöèÿ 3 4020 4020 4020 4020 4020 4020 4020 4020 4020 3900
20100 45.14
44.19 45.08 44.41 43.69
Ñåêöèÿ 2 4020 4020 4020 4020 4020 43.14 42.96 42.18
41.92 41.58 41.09 40.77 40.61
40.45
20244 39.04
37.52

Ñòúëá 38
36.00
Ñåêöèÿ 1 4039 (20216)
Ñòúëá 28

4092 4072 4021 4020 34.48

Ñòúëá 36
Ñòúëá 29

Ñòúëá 37
32.86
Ñòúëá 25

Ñòúëá 26
Ñòúëá 24
Ñòúëá 23

20317 (4077) (4062) (4036) 31.44

Ñòúëá 27

Ñòúëá 31
29.92

Ñòúëá 35
Ñòúëá 30

Óñòî é
Ñòúëá 32
28.40
Ñòúëá 22

(20250)

Ñòúëá 34

2925
Óäúëæåí èå 170 3937 4095 4095 4095 4095 26.88
Ñòúëá 21

Ñòúëá 33
25.25
Ñòúëá 20

(3930) (4080) (4080) (4080) (4080) 23.84

Ñòúëá 19

22.32
20.96
19.46
Ñòúëá 11

Ñòúëá 12

Ñòúëá 13

Ñòúëá 14

Ñòúëá 15

Ñòúëá 16

Ñòúëá 17

Ñòúëá 18
Ñòúëá 10

17.81 (20.71)
Ñòúëá 9

16.37 (19.11)
Ñòúëá 8

14.83 (17.46)
Ñòúëá 7
Ñòúëá 5
Ñòúëá 4

13.28 (16.02)
Ñòúëá 6

(1675)

(14.48)
(1440)

1710

11.74
(1197)
(1043)

1475
1232
1078

(12.93)
(1070)
1105
(840)

(11.39)
875

-0.28

Figure 1. Side view of Asparuhov bridge

From the static point of view, this decision was not the best, but the reduction of
the support parameters of the continuous bridge construction in the interest of the
inclusion of the pre-stressed concrete in this unique bridge led to the appearance of
negative support reaction at the abutments. However the central steel part of the
bridge was designed with contra-weights at the end supports to prevent negative
support reactions. The contra-weights ware executed by concrete ballast.
The bad soil conditions excluded arc or frame structures because of the presence
of big horizontal support reactions. Nowadays the bridge is a part of the European
route E 87 (fig. 2).

Figure 2. View of the bridge

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2. GENERAL DESCRIPTION OF THE BRIDGE STRUCTURE

The central part of the bridge consists of 3-span continuous beam which rises up to
50 m above the canal (fig. 3)[9]. Still now it is one of the highest bridge in Bulgaria.

Figure 3. Steel part of the bridge

The bridge is divided into two parts by a longitudinal gap and completely
independent substructure. The deck of each of the two parallel parts is 7.5 m wide
with two lanes in each direction (fig. 4).

Figure 4. During the construction process

The central steel part of the bridge which passes over the canal is placed
symmetrically in a vertical curve with a radius of 10 000 m. It is a three-span
continuous orthotropic box beam. The box section is 5.5 m wide and has a varying
depth from 4.0 m at the middle of span to 6.4 m at the main supports. The depth of
the box section at the end supports is 2.6 m. The orthotropic deck plate has a varying
thickness from 12 to 20 mm. The longitudinal ribs are 200 mm deep and thicknesses
of 12, 16 and 20 mm depending on the plate thickness and the stress field distribution.
The distance between them is 300 mm (fig.5).

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Figure 5. Box girder cross section and the assembling process

The transversal beams are T-shaped fabricated sections with web dimensions of
550 mm × 8 mm and flange dimensions of 100 mm × 10 mm. The distance between
them is 2 m.
The webs of the box section have a constant thickness of 12 mm and the bottom
plate of the box has a varying thickness of 10 to 20 mm depending of the stress
distribution. The webs are stiffened in axial direction by 120 × 12 mm and 160 × 16
mm ribs. The stiffening of the bottom plate is made by ribs with dimensions 160 × 12
mm, 200 × 16 mm and 220 × 20 mm. The transversal stiffening of the box webs and
the bottom plate is same as the bridge deck. The overall stability of the box section is
solved by adding of V- and X-shaped braces placed every 4 m (fig. 5). The
connections between the assembly units are made by high-strength bolts according
DIN 6914-18 (fig. 6).

Figure 6. Connection process of the assembly units

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The pier bearings are steel rollers produced by Creutz (fig. 7).

Figure 7. Steel Roller bearing

The bridge piers are two-column hammerhead bents (fig. 8).

Figure 8. Bridge piers

The pier foundation is set on very complex soil conditions. The columns are
supported on pile foundation which consists of six cast-in-place concrete piles with
diameters of 1.2 m and up to 53 m depth.

3. LOADS, ANALYSIS AND DESIGN

In the preliminary design the orthotropic structure was analyzed as continuous
beam with spans of 80.5+160+80.5 m [2, 7, 11].
The design loads are as follows:
 Dead loads- self-weight of the structural components;
 Live loads- uniformly distributed load of 3 kPa on the sidewalks;
 Snow loads- uniform load of 1.0 kPa on the bridge deck and sidewalks;
 Moving loads- N 30 and NK 800 according to [5];

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 Breaking forces- result of two-columns of trucks N30, equal of 540 kN;

 Wind loads- for unloaded bridge = 2.5 kPa and for loaded bridge = 1.25 kPa;
 Temperature loads- uniform temperature of ± 40° C and temperature gradient
of 4° C/m;
 Support settlement – in vertical direction and equal of 30 mm;
 Seismic loads- according to Bulgarian code 1972.
The loads are transmitted to the transversal beams by the longitudinal ribs. The
load distribution was obtained by influence lines techniques for the support reactions
of multi-span continuous beam with rigid supports. The bending moments of the
transversal beams and the longitudinal ribs were calculated as moments in an
orthotropic plate according to the [2] theory and verified by the theory of Pelikan and
Esslinger [11].
The detailed analysis of the bridge was made by a 3D frame model using the finite
element computer program STRUDL [10]. The structure was designed in accordance
of the German codes [3, 6] for all loads [5] acting on the bridge during the assembly
process and in operation. Additional design checks were performed taking into
account the St. Venant torsion and the warping restraint torsion [1]. Steel was
modeled el ic pe fec ly pl ic m e i l (P nd l’ l w). The bili y of he
critical sections in all phases of the assemblage is checked using [4] and Kloeppel
design tables [8].

4. USED MATERIALS, MANUFACTURING AND ASSEMBLAGE OF THE

BRIDGE
The bridge design calculations were made assuming the structural steel
St15XCND, class C36/52 for the main structural elements and StM16CC, class
C24/36 for secondary elements. All steel have to be supplied from Soviet Union.
Because of the commercial considerations the class of the high-strength steel was
changed to St 52-3 imported from West Germany.
There is a problem in welding process due to the chemical properties of the used
steel and the welding requirements for the bridge structures. These problems were
cce f lly ol ed by he m in welding con c o “KZU” wi h he c i e ppo of
the Paton Institute in Kiev, Ukraine. At the beginning of 1975 Varna shipyard was
produced the first steel sheets of Asparuhov bridge. During the production process
was used modern automatic CAM line for steel sheet cleaning, priming, cutting and
welding. The production and tests of all bridge parts with a total weight of 24 000 kN
was finished in 17 months (fig. 9 and 10).

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Figure 9. The assemblage process with open cross-section

Figure 10. The assemblage process

5. METHOD OF CONSTRUCTION
The bridge structure was assembled by using of semi-cantilever launching method.
The process starts from the intermediate piers. The first three segments were placed
over the pier and at the neighboring spans using temporary assembling supports. The
launching process continuous with the segments on the end spans using two
assembling support structures. The same assembling structures were used for
launching of the segments into the main span. During the assembling process two
tower cranes was used- BK 1000 and BK 300 (fig. 11), [12].

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Figure 11 The assemblage process with two tower cranes BK 1000 and BK 300

The launching operation of the main structure was completed in 7 months and was
followed by the installation of the sidewalks and safety railings.

6. PAVEMENT AND WATERPROOFING

The pavement consists of 3 mm polymer epoxy resin for waterproofing, a 45 mm
thick layer of medium grained asphalt and a cover layer, 45 mm thick, made of fine
asphalt mixture. The bond between the steel structure and the waterproofing layer was
improved by sand blasting of the steel deck to remove rust and any other debris and
impurities.

7. NONDESTRUCTIVE TESTING OF MATERIALS AND WELDS

The quality of the structural steel was tested non-destructively by ultrasonic device
befo e c ing he hee . The l defec in eel w del min ion of he hee ’
edge . All weld m de “in i ” w e ed by X-rays.

8. STRUCTURAL TESTING
The final tests of the complete structure were made just before the opening of the
bridge. The testing load consisted of trucks loaded with military tanks, which
provided 100 % of the design load. The response of the structure was controlled by

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measuring of the deflection and strains in the middle of the main span. The dynamic
response of the bridge in a longitudinal direction was tested by simulation of an
impulse, caused by the motion of a particular vehicle along the bridge at various
speeds.
The tests showed that the Asparuhov bridge in Varna is designed and constructed
according to the design code and can be put in operation [4].

9. CONCLUSIONS
The steel orthotropic bridge over the ship canal in Varna is an example of an
effective structural solution for large span bridges. Since the region of Varna is an
active seismic area, earthquake loads have to be considered[9]. However, the
structure was proven to be ideal for earthquake regions. The technical tests proved the
high quality of the structure.
The construction of Asparuhov bridge can be treated as one of the best
achievements of the Bulgarian bridge engineering. This important and complex
bridge has been operating successfully about 40 years (fig. 12).

Figure 12 General view of the bridge

ACKNOWLEDGEMENTS
"This paper is dedicated to the 75 birthday of the great bridge Engineer
Radomir Folić“.

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REFERENCES
[1] yno , M., Dimi o , D. nd yko , P., 1977, “ eel c e of A p ho
Bridge- V n ”, Jo n l of Roads, Vol. 16, No:2, pp.4-8.
[2] o neli , W., 1952, “Die e echn ng de ebenen Fl echen gwe ke mi Hilfe
der Theorie der orthogonal- ni o open Pl e”, De hlb , Vol. 21, pp.21-24;
43-48; 60-64.
[3] DIN 1073, 1973, Staehlerne Strassenbruecken, (Berechnungsgrundlagen).
[4] DIN 4101, 1970, Geschweisste staehlerne Strassenbruecken, (Berechnung,
Bauliche Durchbildung und Ausfuerung)
[5] DIN 1072, 1967, Strassen und Wegbruecken, (Lastannahmen)
[6] DIN 4114, 1961, Stabilitaetsfaelle
[7] Hawranek, A., Steinhardt, O., 1958, Theorie und Berechnung der Stahlbruecken,
Berlin-Goettingen-Heidelberg, Springer Verlag.
[8] Kloeppel, K., 1960, Beulwerte ausgesteifer Rechteckplatten, W. Ernst.
[9] N ideno , M., “A p ho idge-Structure strengthening Accosrding to BS-
EN-1998-2-Project Research, Proceedings, 15-th International Scientific
Conference VSU/ 2015,4-5 June, Sofia,pp.164-160.
[10] STRUDL 1973, Manuals of the computer program STRUDL-II, MIT,
Massachusetts.
[11] Pelikan, W., Esslinger, M., 1957, Die Stahlfahrbahn, Berechnung und
Konstruktion, Ausburg-Nuernberg, MAN- Forschungsheft, No7.
[12] oy no , L., Mih ilo , h., 1977, “ peci l fe e in o g niz ion nd
echnology of embly of eel c e of A p ho idge”, Jo n l of
Construction, Vol. 24, No:10, pp.1-7.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.2/.8+625.73
1
Slobodan CVETKOVIĆ
Zoja GORONJA 2

TRACK ARRANGEMENT ON THE RAILWAY BRIDGES WITH

OPEN DECK
Abstract: All railway lines in “ex-Yugoslavia” have steel bridges with open deck. The existing designs
for the track on these bridges are not in compliance with European standards and cause problems for
smooth train ride, as well as problems with safety and stability of the bridges. Paper gives a
comprehensive approach to a.m. problems based on findings during bridge inspection of 15 railway
bridges in Montenegro (Railway line Vrbnica – Bar as part of Beograd – Bar Railway line).ia.

Кey words: Track, Bridge, Open deck, Rail fixing, Resistance to longitudinal movement, Interaction
track/bridge.

UREDJENJE KOLOSEKA NA ZELEZNICKIM MOSTOVIMA SA

OTVORENIM KOLOVOZOM
Rezime: Na svim zeleznickim prugama u “ex-Jugoslaviji” postoje zeleznicki mostovi sa otvorenim
kolovozom. Postojeci projekti za kolosek na tim mostovima nije u skladu sa Evropskim standardima i
uzrok su problema u saoracaju, kao i sa bezbednoscu i stabilnoscu mostova. Rad daje sveobuhvatan
prilaz gore navedenim problemim koji je baziran na nalazima prilikom pregleda 15 zeleznickih mostova
u Crnoj Gori (pruga Vrbnica – Bar kao deo pruge Beograd – bar).

Ključne reči: Pruga, most, otvoreni kolovoz, pricvrsni pribor za sine, otpor pri poduznim pomeranjima,
interakcija kolosek/most.

1
C&N Consult, Beograd, Beograd, Zivojina Zujovica 2 – suite 1B, slobodacvetkovic@yahoo.com;
2
C&N Consult, Beograd, Beograd, Zivojina Zujovica 2 – suite 1B, zojagoronja@gmail.com

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1. FOREWORD
During Summer 2014, a team of engineers was checking the existing condition of
15 steel railway bridges in Montenegro (Railway line Vrbnica – Bar as part of
Beograd – Bar Railway line). Two of them was built in sixties and rest of them in
seventies of the last century. Seven bridges have open deck, one is with direct rail
fixation and 7 has ballast.
At the beginning of the task, we collected all allowable technical documentation
concerning these bridges, as well as codes that were valid for their design. Based on
findings, the rehabilitation designs were later done. The designs were based on
Eurocodes. At the beginning, we were thinking that collecting of the old codes will be
routine task, but we were completely wrong. We tried to get them from few sources,
but most of them we could not find even in the official library of Serbian (Yugoslav)
Railways as well as in the library of Official Gazette of Yugoslavia. Finally, using
our private connections, we was able to have all codes oh Yugoslav railways that
were valid for design of bridges dated from thirties of last century up today. This data
is not important for subject of this paper, but can be interested for future similar tasks
for bridges on Serbian Railways.
Analyzing existing bridges and specially, their serviceability state, few problems
were pointed out:
 Almost half of analyzed bridges do not fulfill the serviceability limits. We were
aware that standards that were valid for their design requested only check of
bridge deflection, but few bridges have absolutely wrong schedule of bridge
bearings from the aspect of railway tracks and train ride. Similar problems we
found even in the recent bridge designs. It means, that bridge designers make
designs in the way to get the bridge structures that correspond to their
knowledge, with intentions of as much as possible to have „copy – paste“ items
and to reduce and concentrate structural calculations and drawings – in the
most cases they do not care about future railway traffic – the bridge itself is
most important for them. The program of actual university studies is mainly
orientated to the motorway bridges, not to the railway bridges. Beside this fact,
the structural engineers have very poor or no knowledge of the railways.
According to existing practice in Serbia, the civil (railway) engineers are
dealing with interaction between track and bridge using methods and structural
modeling that are in practice minimum thirty years ago. But, this practice is
completely wrong – first: they, generally, do not completely understand the
bridge behavior; second: they apply CWR almost everywhere, neglecting real
bridge characteristics; third: they follow existing rule books of Serbian
Railways that are not in compliance UIC and Eurocodes.
 Recommendations of the Rule books “314 Pravilnik”, “330 Uputstvo” and
“347 Uputstvo” for track arrangements on the bridges with open deck are not in
compliance with “316 Pravilnik”, as well as with UIC 774-3R and Eurocodes

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regarding to the transfer of longitudinal forces from the track to the bridge
structure.
 All railway bridges have a problem with service life of the stringers and cross
beams. The „old“ codes for railway bridge design gave approximate formulas
how to calculate stringers; there was no need for fatigue check of railway deck
grid elements. But, nature of the railway loading cause much more severe
fatigue stressing of these elements comparing with main girder elements. Plus,
in the case of truss bridges with stringers in the plane of bottom truss chords,
there is additional tension axial force due to interaction of the stringers with
main girders. The real traffic statistic for whole service life of the existing
railway lines does not exists – it means that is very hard to calculate fatigue
damages by traffic simulation. The best way how to evaluate the remaining
service life of the stringers and cross beams is to cut a piece of the flange where
it is most severe fatigue stressed. This operation requires experience and skilled
labor as well as coordination with existing railway traffic. In this case, you
have piece of the steel for fatigue testing – result should be curve which
indicates remaining steel service life. Some of our colleagues followed the
practice of steel sampling, but they mainly took samples from bridge bracings
in order to avoid complicated procedure of the stringer repair after sampling.
Later, they presented the results from fatigue testing as relevant ones –
unfortunately non competent Railway engineers accepted them. This happened
because all designs for Serbian Railways were not transparent - all were settled
in the circle of connected companies.
 The problem with stringer supports in the case when they lie over cross beams
were also recorded on the few bridges. Using approximate formulas for stringer
design, bridge designers forgot that high negative support reaction can occur
and, as concrescence, the improper detail of the supports was executed – lifting
of the stringers on the supports was recorded as well as cracking in the zones of
supports.

2. FORCES IN CWR
The demands on existing railway bridges regarding loads, speeds and robustness
will continue to increase. In order to meet the present and future demands on
improved capacities for passenger and freight traffic on the existing railway network,
it is of vital importance to upgrade the existing railway bridges and ensure that they
will behave properly under increased loads and designed speeds during their
remaining service life.
Long welded/continuously welded rails (CWR) have become an inseparable
component of modern railway track structures due to their maintainability, safety and
riding comfort.
On the railway line Vrbnica – Bar, the rails 49E1 on wooden sleepers with K
fastenings, are used. The steel grade of the installed rails are R200 (Rmmim = 680
MPa) and R260 (Rmmim = 880 MPa),.

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Fig.1 Longitudinal stress in the rail

The longitudinal stress in the rail have three main causes:
i. Stress due to thermal effect
In a CWR track the sleepers prevent displacement of rails through the track
fastening elements. After the rails are clamped, any temperature change can cause
thermal stresses in the rails due to restriction of movements. In the case of concrete
prestressed bridges, the effect of the concrete shrinkage and the creep should be
added to the thermal forces.

Fig. 2 Force diagram for CWR under temperature variations

Continuous welded rail includes a "central" zone where expansion and contraction
are completely prevented and two "breather" zones at each end, some 150 m in
length. Expansion devices at the ends of the CWR have a variation of opening of 50
mm and permit the free movement of the ends of the CWR.
ii. Mechanical stress caused by Live Load
To determine mechanical stress in the case of the bridges with ballast-less track is
very complicated task and there depends of the bridge characteristics, rail fastening
system as well as of details of the sleeper fastening to the bridge stringers.
At the approach to the bridges there is the same range of problem – you have to
take care about vertical and horizontal displacements of the bridge ends under Live
Load, as well as about the location and of first few sleepers and their 3D spring
constants under effect of Live Load.
iii. Residual stress caused by processes in rolling mill and welding on the site.

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3. ALLOWABLE STRESS IN RAILS

According to Rule Book „347 Pravilnik“, allowable stress in the rail due to all
effects (Residual stress to be taken into account as 80 Mpa) should be less than
 Rails grade 700 MPa ... 410 Mpa
 Rails grade 900 MPa ... 460 MPa
UIC 774-3R, as well as EN 1993-2 has different approach – they limited stress due
to temperature effects:
Theoretical stability calculations, on UIC 60 CWR, of a steel grade giving at least
900 N/mm2 strength, minimum curve radius 1 500 m, laid on ballasted track with
concrete sleepers and consolidated > 30 cm deep ballast, well consolidated ballast,
give a total possible value for the increase of rail stresses due to the track/bridge
interaction.
The maximum permissible additional compressive rail stress is 72 N/mm2.
The maximum permissible additional tensile rail stress is 92 N/mm2.
In case of other rails than UIC 60 the permissible additional compression and
tensile rail stresses should be specified by the relevant authority.
If we apply UIC requests to our case, ie.to the rails 49E1, grade 900,
∆RT = (9.2 + 7.2) / (0.000012*21000) = 65OC ,or for rail grade 700
∆RT = (9.2 + 7.2) * (700/900) / (0.000012*21000) = 51OC
If we apply UIC requests to our case, ie.to the rails 49E1, grade 900, and under
assumption that track is secured from lateral buckling, we have
∆RT = 2*9.2/ (0.000012*21000) = 73OC (track without buckling),
or for rail grade 700
∆RT = 2*9.2 * (700/900) / (0.000012*21000) = 57OC (track without
buckling),
Old codes for steel structures required to take into consideration temperature
elongation for T = +/- 35°C + ∆T = +/- 15°C, measured from neutral temperature
+10°C. Practically, in the rail stress calculation you have to take limits -25°C and
+60°C, ie. ∆RT = 85°C. The rail temperatures of +60°C and -25°C are real for
climate in the most parts of Serbia (temperature of the rail +60°C and higher had
been recorded many times on Serbian railways). EN 1991-1-5 gives different (more
sophisticated, based on statistic) method for estimation oflocal temperature limits,
but final results are similar.
Conclusion of a.m. analysis:
 CWR should not be allowed for rails grade R200,
 Local temperature conditions should be analyzed for CWR grade 260,
 Allowable stress approach given by Rule Book „347 Pravilnik“, due to high
variation of effects at the bridge ends and in transition area, is not on the safe
side in the practice.

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 The racks in the transition area (bridge to embankment) should be secured

against lateral buckling.
 The neutral rail temperature for calculation of thermal elongations should be
between 20oC and 25oC … average 23oC.

4. CORRELATION BETWEEN CWR AND BRIDGE EXPANSION LENGTH

Rule Book “314 Pravilnik” gives the instruction about correlation between
expansion length of the bridge structure and track with fish-plates as follows:
Track Expansion
on the length of the Necessary measures
bridge bridge
with up to
At the both ends of the expansion length normal rail joints
ballast 60 m.

over Steel and composed bridges at movable bearings – rail expansion device
with
and transversal joint in ballast that corresponds to the elongation of the
ballast 60 m. bridge structure
without up to
Independent elongation of the rails or track over bridge structure
ballast 60 m

60 m – Rail expansion device or Independent elongation of the track over bridge

without
structure. Fixed connection of the track to the bridge structure + rail
ballast 120 m. expansion joint at movable bearings

Rule Book “330 Uputstvo” gives the instruction about correlation between
expansion length of the bridge structure and CWR track as follows:
Track Expansion
on the length of the Necessary measures
bridge bridge
with up to Independent elongation of the rails or track over bridge structure. CWR at
ballast 50 m. approaches in length 120 – 150 m.
Rail expansion device (capacity that covers elongation of the bridge and
with over CWR on embankment) 5m. – 10 m. behind abutment with movable bridge
ballast 50 m. bearing + small rail expansion joint 5m. – 10 m. behind abutment with
fixed bridge bearing

up to Independent elongation of the rails or track over bridge structure. CWR at

without
approaches in length 120 – 150 m. Longitudinal fixation of the rails before
ballast 50 m and behind bridge.
Rail expansion device (capacity that covers elongation of the bridge and
without Over CWR on embankment) 5m. – 10 m. behind abutment with movable bridge
ballast 50 m. bearing + small rail expansion joint 5m. – 10 m. behind abutment with
fixed bridge bearing

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UIC 774-3R , paragraph 1.5.6 - Rail expansion devices, gives following:

It is preferable to avoid expansion devices in the track, but one should always be
inserted at the free end of the deck if the total additional rail stress or the
serviceability displacements exceed the permissible values. The maximum
expansion length of a single deck carrying CWR without expansion device will be:
 60 m for steel structures carrying ballasted track (maximum length of deck
with fixed bearing in the middle:120 m),
 90 m for structures in concrete or steel with concrete slab carrying ballasted
track (maximum length of deck with fixed bearing in the middle: 180 m).
In the case of un-ballasted track, a specific evaluation should be done.
Even when the calculated stresses and displacements do not exceed the
permissible values, it may be necessary to fit an expansion device in the track.
This is the case when the daily variation of the length of the deck exceeds the
permissible values taking into account the track maintenance conditions
(permissible AL to be defined by each railway; generally between 10 and 15 mm).
Note: A.m. is valid for track with concrete sleepers, rails UIC 60, continuous
ballast.
SYSTRA in their Bridge Design Manual gives 80 m. as limit for CWR for track
with concrete sleepers, rails UIC 60, continuous ballast.
Comment
According to Rule Book “316 Pravilnik”, the bridge structure has to take
acceleration / braking forces from the rails and to transfer them to the fixed bridge
bearings. The a.m. statement “Independent elongation of the rails or track over
bridge structure” is not in compliance with “316 Pravilnik” request – In my 45 years
long engineering practice I never saw any device on the railway bridge that is able to
transfer to the structure high longitudinal forces on the bridges that are designed with
movable track/rail connections, but many of these bridges have been reconstructed
due higher longitudinal forces than originally designed (differences in issues of “316
Pravilnik”). It means that bridge designers and railway civil engineers do not
coordinate their designs.

5. FIXING OF THE RAILS

This paper is dealing with bridges with open deck. Open deck bridges have
sleepers supported directly on load-carrying elements of the structure (such as
stringers or girders). The dead loads for open deck structures can be significantly less
than for ballast deck structures. Open decks, however, transfer more of the dynamic
effects of live load into the bridge than ballast decks. In addition, the bridge sleepers
required are both longer and larger in cross section than the standard track sleepers.
This adds to their expense. Bridge sleeper availability has declined, and their supply
may be a problem, particularly in denser grades of structured timber.

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Fig.3 Typical arrangement of the track on the railway bridge with open deck

The most part of railway lines in Serbia and Montenegro have wooden sleepers
26/24 cm with rigid “K” fastening. The contact between rail and steel ribbed base-
plate is over rubber pads or over wooden poplar pads. Standard tightening torque
applied to hook bolts in “K” rail fastening is in the range of 180 – 250 Nm – lock
springs under nuts are always fully compressed.
Recommendations given in “314 Pravilnik”/ “330 Uputstvo” how to grind
clamping plates in order to reduce clamping force to the rail are illustrated on the
Figure 4.

Fig. 4 Modified clamping plate according recommendations in rule books

If you look the drawing or photo with grinded (modified) clamping plates you can
notice that gap exists between ribs of the base plate and clamping plate – simply, the
a.m. recommendations are wrong – the grinded clamping plate induce to the rail the
same clamping force as standard one.

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Fig 5. Modified clamping plate installed on the bridge

If you want to establish real longitudinally movable connection of the rail , than
you have to grind a “K” clamping plate as it is given on the Figure 6 and to install
under-rail pads made of EVA or elastomeric covered by Teflon (Fabreeka). The
standard under-rail rubber pads can be also used if a 1 mm thick stainless steel plate,
H shape, is inserted between pad and rail bottom. This solution can be applied on
tracks with minimum curve radius 1 500 m, but, if you have smaller radius, the
torsion rigidity of the connection is questionable.

Fig 6 Modified “K” clamping plate with zero force.

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The real solution for rail fixation with free longitudinal movements is Pandrol
modified K-lock fastening. It use standard “K” ribbed base plate, rail is laying over
EVA pads, “H” shaped, and has combination of fixed and elastic clamps.

Fig. 7 Pandrol modified K-lock fastening

In the case that you decide to arrange the track on bridge with longitudinally
movable rail fixation, you are obliged to fix the track to the bridge structure, as it is
mentioned in paragraph 4 of this article. In the rehabilitation design for bridges on
railway line Vrbnica – Bar, it was used damping device as shown on the Figure 8.
Fiber reinforced pads are dampers, but the problem is that they cannot act in reverse
without force. The solution with hydraulic dampers is much better – see Figure 9.
Hydraulic dampers are always in the neutral position due to their construction, they
allow movement of ± 5 mm. caused by external forces.

Fig. 8 Longitudinally fixation of the rail on the bridge

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Fig. 9 Detail of hydraulic damper (top) and position of dampers in rail fixation device.

Hydraulic damper, at this moment, is under testing.

In the case that you decide to arrange the track on bridge with longitudinally
movable rail fixation, you are obliged to fix the track to the bridge structure, as it is
mentioned in paragraph 4 of this article. In the rehabilitation design for bridges on
railway line Vrbnica – Bar, it was used damping device as shown on the Figure 8.
Fiber reinforced pads are dampers, but the problem is that they cannot act in reverse
without force. The solution with hydraulic dampers is much better – see Figure 9.
Hydraulic dampers are always in the neutral position due to their construction, they
allow movement of ± 5 mm. caused by external forces.

6. FIXING OF THE SLEEPERS TO THE BRIDGE STRUCTURE

The sleepers on all steel bridges with “open deck” are standard wooden,
dimensions 26 x 24 cm. The safe rails inside of the rack are installed on all bridges
and 15 m. at the approaches . Guard wooden beams outside track are also installed on
the most of the bridges. It means that horizontal rigidity of the track grid is much
more higher on the bridge than on the embankment.- this fact have to be taken into
consideration in design of track lateral supports before and behind the bridge.

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Fig. 11 Sleeper fixation with “L” bolt. Visible

deformation of the stringer’s top flange

Fig.10 Sleeper fixation with steel angle

profile (located over “braking”
bracing)

The fixation detail of the sleepers to the bridge stringers varies from bridge to the
bridge, but “L” bolts are standard fixation device. The “L” bolts that are used on steel
railway bridges in “ex Yugoslavia” have a defect – their attaching head can be easily
rotated under traffic influence.

Fig. 12 Sleeper fixation with steel angle Fig. 13 Sleeper is laying on steel welded
which can move along stringer’s rail. chair

Uplifting of the sleeper prevented with “L” bolts.

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Fig. 14 Improvised “L” bolt

Comment
Detail of the “L” bolt is not changed in “ex Yugoslavia” railways more than 50
years. Maybe, the proposal of new shape of “L” bolt can be accepted – see next
figure.

Fig. 15 Elastic “L” bolt (add double spring washer under bolt nut for better connection)

7. TRANSITION ZONE
Transitions zones are sensible points of railway line. The challenge of this zone
consists in maintaining low deformability levels, allied to very high stresses and good
passenger’s comfort levels. Transition zones embrace different sub-systems and have
the challenge to connect different zones in the best possible way, like an embankment
or a bridge. The
track-bridge interaction will be responsible for shear stresses on the top of
transitions zones, specially when bridge is with open deck. Even when there are any
train passing, due to track bridge interaction, the top part of the transition zone will be
supporting shear stresses due to thermal effects, creep and shrinkage. During train
passage, the deck will deform and the CWR will adapt to this deformation. The

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sleepers above the transition zone will tend to float (Fig. 16) and the shear stresses in
the top of the transition will be increased. When the train is in both sides (bridge ant
transition) the sleepers will be pushed to the ballast and the vertical loads will
increase due to this dynamic effects (Fig. 17). Finally, only the transition will be load
by the train (Fig. 18).

Fig. 16 Train on the bridge – floating Fig. 17 Train on the bridge and embankment
sleepers in transition zone

Fig. 18 Train on embankment

In the UIC 719R, many solutions are showed for transitions zones. Most of them
use soil wedges as a solution for the different stiffness of the embankment and
structure zone.
The French SNCF/RFF transitions solutions, consulted in the “Remblaiscontigues
aux Maconneries” (SNCF/RFF2002), shows different solutions according to the
structure type (inferior passage, abutment characteristics, hydraulic passages, etc),
embankment height - H (H > 10m, 4m ≤ H ≤ 10m, 3m ≤ H ≤ 4m e H < 3m ), and
construction timing(embankment constructed before or after the structure). Example
of such transition zone is given on the Figure 19.
During the inspection of the 15 steel bridges on railway line Vrbnica – Bar,
effects explained by Figures 16 – 18, were recorded. Beside these, almost on all
bridges (exception Mala Rijeka) was noticed that parapet wall on the embankment did
not prevent ballast from falling down. As consequence, the bridge bearings were

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covered with stone from ballast with possibility that bearings could be blocked. Due
to this fact, as well as to improve train ride from “soft” to “rigid”, the sleeper with
elastic pads was installed on the top of parapet wall, instead standard solution where
sleeper is just behind parapet wall.

Figure 19 Connection embankment - bridge

Fig. 20 Sleeper arrangement in transition zone

8. INTERACTION TRACK - BRIDGE

The advantages of continuation of joint-less CWR over bridges are too obvious.
The identification and understanding the behavior of the track and bridges are crucial
in order to avoid eventual damages of the sleepers or the bridge bearings. On almost
all inspected bridges with open deck that have no rail expansion device, some
irregularities had been recorded – some of them very serious damages of bridge
bearings (bridge bearings were the weakest pint) or cracking of relatively new
sleepers.
The advantages of continuation of joint-less CWR over bridges are too obvious.
The identification and understanding the behavior of the track and bridges are crucial
in order to avoid eventual damages of the sleepers or the bridge bearings. On almost
all inspected bridges with open deck that have no rail expansion device, some
irregularities had been recorded – some of them very serious damages of bridge
bearings (bridge bearings were the weakest pint) or cracking of relatively new

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sleepers – all caused by wrong design of the permanent way followed with non-
adequate structural calculation of interaction track / bridge.
As discussed in Paragraph 4 of this paper, on the bridges with open deck, for
bridge expansion length less than 30 - 35 meters, the track should be provided with
rail “free fastening” and with rail longitudinal fixation near bridge fixed bearings. If
the expansion length of the bridge is more than a.m. limit, it is necessary to install rail
expansion device near movable bridge bearing.

Fig. 21 High forces from the track damaged Fig. 22 Cracks in sleepers
anchors of the bridge fixed bearings

The EN 1991-2, as well as UIC774-3R, give the recommendations for structural

calculation of the interaction track : bridge. Also, “347 Uputstvo” gives example for
structural modeling. All structural calculations that are mentioned in a.m. codes are
based on simplified structural models. Today, most of our engineers are orientated to
TOWER software, so no need to work with few simple structural models. In the 3D
model of the bridge that was used for calculation of the forces and deflections, simply
insert the track grid in length of :
on embankment in front/behind movable bridge bearings: ~ 2 x expansion length
of the bridge + bridge +on embankment in front/behind fixed bridge bearings: ~ 10
m.
What you will need are data about track resistance in ballast (summer / winter) and
soil/foundation characteristics of the bridge abutments and piers. Also, you have to
take care about modeling of springs that represent resistance of the track (non-linear).
8.1. Resistance of the track in ballast
EN 1991-2
The longitudinal load/ displacement behavior of the track or rail supports may be
represented by the relationship shown in with an initial elastic shear resistance
[kN/mm of displacement per m of track] and then a plastic shear resistance k[kN/m of
track].

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UIC 774-3R
UIC 774-3R gives the same diagram as EN 1991-2. The conventional values
assumed for ballasted track, with reference to Fig. 21, are as follows:
 Displacement u0 between elastic and plastic zones:
uO = 0.5 mm for the resistance of the rail to sliding relative to the sleeper
uO = 2.0 mm for the resistance of the sleeper in the ballast.
 Current values of resistance k in the plastic zone:
k = 12 kN/m Resistance of sleeper in ballast (unloaded track), moderate
maintenance,
k = 20 kN/m Resistance of sleeper in ballast (unloaded track), good
maintenance,
k = 60 kN/m Resistance of loaded track or track with frozen ballast.

Fig. 23 Variation of longitudinal shear force with longitudinal track displacement for one
track – EN 1991-2 / UIC 774-3R

347 Uputstvo
Calculation of the stress in the rails as well as calculation of the rails’ longitudinal
displacement should be done based on the track longitudinal resistance:
p = b ∙ um
where m = 0.25 – 0.45, and b = 75 – 80 for non-frozen ballast, or
m = 0.13 – 0.2, and b = 150 – 160 for frozen ballast.

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This recommendation allows also to use direct value for resistance of the sleepers
in non-frozen, tamped ballast:
p = 50 N/cm for concrete sleepers
p = 40 N/cm for wooden sleepers
In “347 Uputsvo” , there is more data and recommendations for calculation, but it
gives very simple model (based on software STRESS from seventies) which can not
accept non-linear correlation between longitudinal shear resistance and longitudinal
displacement.
Dr.ing. Ladislav Fryba

Frozen ballast means literally under snow load when the ballast freezes and
behavies as rigid mass.
(*) Rail, bearing plate, wooden sleepers, stringers
(**) Rail, bearing plate, bridge deck
Units reported by UIC and Rail International are different, i.e. kN/m and N/mm2.
For comparison, modulus of track for longitudinal displacements in linear region can
be defined as K = F / displacement / mm.
For ballasted deck bridges with PSC sleeper track, the values by different studies
are given below:

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Rudney c. Querioz

8.2. Soil properties & modulus of elasticity

The value of Modulus of elasticity, Poisson ratio required for working out
displacements and corresponding stresses in rails and support reaction can play a
very important role in assessment. It is important to understand that we are interested
in short term displacements within the elastic range i.e. when the pore water pressure
is not dissipated or on un-drained properties of soil.
Soil also behaves differently under repetitive loading cycles i.e. its stress train
behavior is different in the loading and unloading cycles. The live load of trains sends
waves of energies to the foundation, which behave like foundations for machines and
the dynamic properties of soil are important under these circumstances. The plot on
Figure 24 shows the relationship between static and dynamic modulus of elasticity of
soil.

Fig. 24 Ratio dynamic modulus to static modulus

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Fig. 25 Suggested basic soil properties

Fig. 26 Suggested values for soil modulus (Geotechnical Engineering Handbook by Ulriche
Snoltczyk, Published by Ernst and Sohn (2002)

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9. EXAMPLE FOR ARRANGEMENT OF THE TRACK

On Figure 27 it is given how we designed the rehabilitation of track on Skadarsko
jezero Bridge – simple span truss beam, L = 30 m. applying Eurocode / UIC requests.

Fig. 27 Track arrangement on Skadarsko jezero Bridge

10. CONCLUSION
The intention of this paper is to wake up Railway authorities and to harmonize
their rule books with European standards. As excuse, we know that they are very
conservative, but they have to understand that today is 21st century.
Because of the fact that Serbia proclaimed that want to join EU, all future design
should be based on European standards – most of them are already adopted by ISS.
The current practice that civil railway engineers make calculation of the
interaction track/bridge is not in compliance with Eurocodes and authorization of
their professional licenses issued by Serbian Chamber of Engineers. They have to be
collaborators in structural design of the bridge. Committee for technical control of
Ministry for infrastructure should have in the mind this fact.

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REFERENCES
[1] Eurocodes: EN 1990 – EN 1994
[2] UIC code 774-3R Track/bridge Interaction Recommendations for calculations
[3] 314 Pravilnik o odrzavanju gornjeg stroja pruga
[4] 316 Pravilnik o tehničkim normativima za određivanje veličina opterećenja i
kategorizaciju železničkih mostova, propusta i ostalih objekata na
železničkim prugama
[5] 330 Uputstvo o ugradjivanju I odrzavanju sina I skretnica u dugackim trakovima
[6] 347 Uputstvo za proračun i ugrađivanje dugih trakova šina na mostovima
[7] Luís Miguel Gouveia Coelho: Structure/Embankment Transitions in Railway
Infra-structures
[8] Ashok K Goel: Continuation of LWR on Bridges
[9] Rudney C. Querioz: Longitudinal Track-Ballast Resistance of Railroad Tracks
Considering Four Different Types of Sleepers
[10] Coenraad Elsved: Modern Railway Track

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ASEISMIC DESIGN OF STRUCTURES
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.042.7
1
Angelos LIOLIOS
Antonia MOROPOULOU2
Doncho PARTOV3
Boris FOLIC4
Asterios LIOLIOS5

CULTURAL HERITAGE RC STRUCTURES STRENGTHENED BY

CABLE ELEMENTS UNDER MULTIPLE EARTHQUAKES
Abstract: A numerical approach is presented for the earthquake analysis of existing reinforced concrete
(RC) structures, which are seismically upgraded by ties elements and subjected to seismic sequences. It
is considered the case of old industrial RC structures, which are elements of the recent Cultural Heritage.
A double discretization is applied by using the Finite Element Method and an incremental time
integration scheme. Damage indices are computed in order to compare the seismic response of the RC
structures before and after the retrofit by cable element strengthening, and so to elect the optimum ties
version. A typical multistorey industrial RC frame is investigated.
Кey words: Cultural Heritage RC Systems, Seismic Upgrading by Ties, Multiple Earthquakes.

AB KULTURNO NASLEĐE POJAČAVANO KABLOVIMA POD

VIŠESTRUKO PONOVLJENIM ZEMLJOTRESIMA
Rezime: Prikazan je numerički pristup seizmičke analize postojećih armiranobetonskih (AB)
konstrukcija, koje su pojačane kablovima-zategama izložene seizmičkim dejstvima. Razmatran je slučaj
starih industrijskih objekata koji su svrstani u kategoriju Kulturnog dobra. Korićena je dvostruka
diskretizacija pri primeni metode konačnih elemenata (MKE) i inkrementalna integraciona shema po
vremenu. Naznačena oštećenja su sračunata da bi se uporedili seizmički odgovori AB konstrukcije pre i
posle intervencije pojačavanja kablovima, i za izbor optimalnog rešenja. Pri tome razmatran je
višespratni okvirni sistem AB industrijskog objekta.
Ključne reči: Kulturno dobro AB konstrukcije, Seizmičko pojačavanje zategama, višestruki potresi

Dedicated to Professor Radomir FOLIĆ for the 75th anniversary of his birth.

1
PhD Candidate, Democritus University of Thrace, Dept. of Civil Engineering, GR67100 Xanthi, Greece, (e-mail:
aliolios@civil.duth.gr)
2
Prof., National Technical University of Athens, School of Chemical Engineering, 9 Iroon Polytechniou Street,
Zografou Campus, GR15780 Athens, Greece (e-mail: amoropul@central.ntua.gr)
3
Prof., Lyuben Karavelov University (VSU), Sofia, Bulgaria, (e-mail: partov@vsu.bg)
4
PhD Candidate, University of Belgrade, Mech. Enging Fac., Serbia, (e-mail: boris.folic@gmail.com)
5
Prof., Democritus University of Thrace, Xanthi, Greece, (e-mail: liolios@civil.duth.gr)

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1. INTRODUCTION
The recent Cultural Heritage includes, besides the usual historic monumental
structures (churches, old masonry buildings etc.), also existing industrial buildings of
reinforced concrete (RC), e.g. old factory premises [1]. As concerns their global
seismic behaviour of such RC structures, it often arises the need for seismic
upgrading. For the recent Cultural Heritage, this upgrading must be realized by using
materials and methods in the context of the Sustainable Construction [1, 18-20, 27].
For the seismic upgrading of usual existing RC structures, many and well-known
repairing and strengthening techniques [5-7, 24] can be used. For the strengthening of
existing Cultural Heritage RC frames against lateral induced earthquake loading, one
of the simple, low cost and efficient method is the use of steel cross X-bracings [2,
16]. The use of cable-like members (tension-ties) instead of traditional RC mantles
can be considered as an alternative strengthening method for inadequate RC frame
structures under lateral seismic actions [15]. As well-known, ties have been used
effectively in monastery buildings and churches arches [1]. Cable restrainers are also
used for concrete and steel superstructure movement joints in bridges [25].
These cable-members (ties) can undertake tension but buckle and become slack
and structurally ineffective when subjected to a sufficiently large compressive force.
Thus the governing conditions take equality as well as an inequality form and the
problem becomes highly nonlinear [11, 12, 14, 17, 21].
As concerns the seismic upgrading of existing RC structures, modern seismic
design codes adopt exclusively the use of the isolated and rare „design earthquake‟,
whereas the influence of repeated earthquake phenomena is ignored. But as the results
of recent research have shown [8, 13], multiple earthquakes generally require
increased ductility design demands in comparison with single isolated seismic events.
Especially for the seismic damage due to multiple earthquakes, this is accumulated
and so it is higher than that for single ground motions [13].
In this study, a numerical approach is presented for the seismic analysis of existing
industrial beam-column RC frames that have been strengthened by cable elements
and are subjected to seismic sequences. The approach is based on an incremental
formulation and uses the Ruaumoko structural engineering software [3]. Damage
indices [9, 22] are computed for the seismic assessment of historic and industrial
structures and in order the optimum cable-bracing strengthening version to be chosen.
Finally, an application it is presented for a simple typical example of a two-bay two-
story industrial RC frame strengthened by bracing ties under multiple earthquakes.

2. THE COMPUTATIONAL APPROACH

Details of the developed numerical approaches are given in [14], whereas the
adopted incremental approach is briefly summarized herein. A double discretization,
in space and time, is applied. The structural system is discretized in space by using
finite elements [4]. Pin-jointed bar elements are used for the cable-elements. The

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unilateral behaviour of these elements can in general include loosening, elastoplastic

or/and elastoplastic-softening-fracturing and unloading - reloading effects. All these
characteristics, concerning the cable full constitutive law, as well as other general
non-linearities of the RC structure, can be expressed mathematically by using
concepts of convex and non-convex analysis [17, 21].
Incremental dynamic equilibrium for the assembled structural system with cables
is expressed by the matrix relation:

M  u +C  u +KT u = -M  u g + A s +p (1)

where u(t) and p(t) are the displacement and the load time dependent vectors,
respectively, and C( u ) and KT (u), are the damping and the tangent stiffness matrix,
respectively. Dots over symbols denote derivatives with respect to time. By s(t) is
denoted the cable stress vector. A is a transformation matrix and ug the ground
seismic excitation.
The above relations combined with the initial conditions consist the problem
formulation, where, for given p and/or u g, the vectors u and s have to be computed.
Regarding the strict mathematical point of view, we can formulate the problem as a
hemi-variational inequality one by following [17, 21] and investigate it.
For the numerical treatment of the problem the structural analysis software
Ruaumoko [3] is used. Here, for the time-discretization, the Newmark scheme is
chosen. Ruaumoko uses the finite element method and provides results which
concern, among others, the following critical parameters: local or global structural
damage, maximum displacements, inter-storey drift ratios, development of plastic
hinges, etc.
Ruaumoko has been also applied successfully for multiple earthquakes concerning
the cases of concrete planar frames [8] and RC frames strengthened by cables [14]. It
is reminded that multiple earthquakes consist of real seismic sequences, which have
been recorded during a short period of time (up to some days), by the same station, in
the same direction, and almost at the same fault distance [13].
After the seismic assessment of the existing RC structure, the choice of the best
strengthening cable system can be realized by using damage indices [9, 22]. In this
study the overall structural damage index (OSDI) is used. In the OSDI model after
Park/Ang [22] the global damage is obtained as a weighted average of the local
damage at the section ends of each frame element or at each cable element. The local
damage index is given by the following relation:
m 
DIL   ET (2)
u Fy d u

where: DIL is the local damage index, μm the maximum ductility attained during the
load history, μu the ultimate ductility capacity of the section or element, β a strength

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degrading parameter, Fy the yield generalized force of the section or element, ET the
dissipated hysteretic energy, du the ultimate generalized displacement.
For the global damage index, which is a weighted average of the local damage
indices, the dissipated energy is chosen as the weighting function. So, the global
damage index is given by the following relation:
n

 DI Li Ei
DIG  i 1 (3)
n

Ei 1
i

where DIG is the global damage index, DILi the local damage index, Ei the energy
dissipated at location i and n the number of locations at which the local damage is
computed.
The proposed numerical approach has been successfully calibrated in [10] by
using available experimental results from literature [16].

3. NUMERICAL EXAMPLE
Figure 1 depicts an old industrial reinforced concrete frame F0 subjected to a
multiple ground seismic excitation. The list of these earthquakes, which were
downloaded from the strong motion database of the Pacific Earthquake Engineering
Research (PEER) Center [24], appears in Table 1. The ground acceleration records of
the simulated seismic sequences are shown in Fig. 2. For various seismic sequences
input details see [8, 13].

Figure 1. The initial RC frame F0 without cable-strengthening.

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Table 1. Multiple earthquakes data

Seismic Magnitude Recorded Normalized
No Date (Time)
sequence (ML) PGA(g) PGA(g)
1983/07/22
6.0 0.605 0.165
(02:39)
1 Coalinga
1983/07/25
5.3 0.733 0.200
(22:31)
1979/10/15
6.6 0.221 0.200
Imperial (23:16)
2
Valley 1979/10/15
5.2 0.211 0.191
(23:19)
1987/10/01
5.9 0.204 0.192
Whittier (14:42)
3
Narrows 1987/10/04
5.3 0.212 0.200
(10:59)

Figure 2. Ground acceleration records of the simulated seismic sequences.

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Using Ruaumoko software [3], the columns and the beams are modeled using
prismatic frame elements [4]. Nonlinearity at the two ends of RC members is
idealized using one-component plastic hinge models, following the Takeda hysteresis
rule. Interaction curves (M-N) for the critical cross-sections of the examined RC
frame have been computed. The effects of cracking on columns and beams are
estimated by applying the guidelines of [6, 23, 25]. The stiffness reduction due to
cracking results to effective stiffness of 0.60 Ig for the two external columns, 0.80 Ig
for the internal column and 0.40 Ig for the beams, where Ig is the gross inertia moment
of their cross-section.

Figure 3. The RC frame F2 with X-bracings cable-strengthening.

Figure 4. Constitutive law of the cable-elements.

After the seismic assessment [6], the X-cable-braces system, shown in Fig. 3, has
been proposed in order the frame F0 to be strengthened. For the cable-elements, the
bilinear with slackness hysteresis rule of Ruaumoko [3] is used. The cable elements
have a cross-sectional area Fc = 18 cm2 and they are of steel class S220. The cable
constitutive law concerning the unilateral (slackness), hysteretic, fracturing,
unloading-reloading behaviour, has the diagram depicted in Fig. 4. Ductility index is
μ = d/dy .

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Concerning the Coalinga case of seismic sequence, representative results are

shown in Table 2. In column (1), Event E1 corresponds to Coalinga seismic event of
0.605g PGA, and Event E2 to 0.733g PGA. The sequence of events E1 and E2 is
denoted as Event (E1+ E2). In table column (2) the Global Damage Indices DIG and in
column (3) the Local Damage Index DIL for the bending moment at the left fixed
support A of the frames are given. Finally, in the column (4), the maximum horizontal
top displacement utop is given.

Table 2. Representative response quantities for the frames F0 and F2

FRAMES EVENTS DIG DIL utop [cm]
(0) (1) (2) (3) (4)
Event E1 0.134 0.179 2.227
F0 Event E2 0.301 0.474 3.398
Event (E1+ E2) 0.334 0.481 3.410
Event E1 0.068 0.007 1.126
F2 Event E2 0.097 0.136 1.447
Event (E1+ E2) 0.108 0.154 1.471

As the above table values show, multiple earthquakes generally increase response
quantities, especially the damage indices. On the other hand, the strengthening of the
frame F0 by X-bracings (Frame F2) improves the response behaviour.

4. CONCLUDING REMARKS
The seismic inelastic behaviour of industrial RC frames strengthened by cable
elements and subjected to multiple earthquakes can be numerically investigated by
the herein presented numerical approach. The optimal cable-bracing scheme can be
selected among investigated alternative ones using computed damage indices.

ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36043 supported by the Ministry for Education Science of Serbia. This
support is gratefully acknowledged (B. Folić).

REFERENCES
[1] Asteris, P. G. & Plevris, V. (Eds.). (2015). Handbook of Research on Seismic
Assessment and Rehabilitation of Historic Structures. IGI Global.
[2] Bertero, V.V. and Whittaker, A.S., (1989). Seismic upgrading of existing
buildings, 5as Jornadas Chilenas de Sismología e Ingeniería Antisísmica, 1, 27-
46.
[3] Carr, A.J., (2008). “RUAUMOKO - Inelastic Dynamic Analysis Program”. Dep.
of Civil Engineering, University of Canterbury, Christchurch, New Zealand.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[4] Chopra, A.K., (2007) . “Dynamics of Structures: Theory and Applications to

Earthquake Engineering”, Pearson Prentice Hall, New York.
[5] Dritsos, S.E., (2001). Repair and strengthening of reinforced concrete structures
(in greek). University of Patras, Greece.
[6] Fardis, M.N., (2009). Seismic design, assessment and retrofitting of concrete
buildings: based on EN-Eurocode 8. Springer, Berlin.
[7] Eurocode 8 (CEN 2004). Design of structures for earthquake resistance, Part 3:
Assessment and Retrofitting of buildings, (EC8-part3), EN 1998-3, Brussels.
[8] Hatzigeorgiou, G. and Liolios, Ast., (2010). Nonlinear behaviour of RC frames
under repeated strong ground motions. Soil Dynamics and Earthquake
Engineering, vol. 30, 1010-1025, 2010.
[9] Ladjinovic, Dj. & Folic, R. (2004). Application of improved damage index for
designing of earthquake resistant structures. In: Proceedings of the 13th World
Conference on Earthquake Engineering, Vancouver, Canada (Paper No. 2135,
pp. 1-15).
[10] Liolios Ang. & Const. Chalioris, (2015). “Reinforced concrete frames
strengthened by cable elements under multiple earthquakes: A computational
approach simulating experimental results”, In: Proc. of 8th GRACM Int.
Congress on Computational Mechanics, Volos, 12 July – 15 July 2015.
[11] Liolios Ang., Chalioris C., Liolios K. . and Folic B. (2012). Strengthening by
cable-bracings of reinforced concrete structures: A numerical approach. In:
Radonjanin V., Folic R. and Ladinovic D. (eds.), Proceedings of the Intern.
Scientific Conference iNDiS 2012, pp. 130-136.
[12] Liolios, Ang., Chalioris, C., Liolios, Ast., Radev, S. and Liolios, K., (2012). “A
Computational Approach for the Earthquake Response of Cable-braced
Reinforced Concrete Structures under Environmental Actions”. Lecture Notes in
Computer Science, LNCS, vol. 7116, pp. 590-597, Springer-Verlag, Berlin
Heidelberg.
[13] Liolios Ast., Hatzigeorgiou G. and Liolios Ang., (2012). Effects of multiple
earthquakes to the seismic response of structures, Building Materials and
Structures Journal, vol. 55, no. 4, pp. 3-14.
[14] Liolios, Ast., Liolios, Ang. and Hatzigeorgiou, G., (2013). “A numerical
approach for estimating the effects of multiple earthquakes to seismic response
of structures strengthened by cable-elements”. Journal of Theoretical and
Applied Mechanics, 43(3), 21-32.
[15] Markogiannaki, O. & Tegos, I. (2011). “Strengthening of a Multistory R/C
Building under Lateral Loading by Utilizing Ties”. Applied Mechanics and
Materials, vol. 82, 559-564.
[16] Massumi, A. and Absalan, M. (2013). “Interaction between bracing system and
moment resisting frame in braced RC frames”. Archives of Civil and Mechanical
Engineering, 13(2), 260-268.

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[17] Mistakidis, E.S. and Stavroulakis, G.E., (1998). Nonconvex optimization in

mechanics. Smooth and nonsmooth algorithmes, heuristic and engineering
applications. Kluwer, London.
[18] Moropoulou, A. (2009). “Current Trends towards the Sustainable Construction.
The Relation between Environment and Concrete”. In: Techn. Chamber of
Greece (TEE) (ed.), Proceedings, 16th Hellenic Concrete Conference, Cyprus,
2009.
[19] Moropoulou A., Bakolas A., Spyrakos C., Mouzakis H., Karoglou A.,
Labropoulos K., Delegou E.T., Diamandidou D., Katsiotis. N.K., (2012). “NDT
investigation of Holy Sepulchre complex structures”, in: V. Radonjanin, K.
Crews, (eds), Proc. of Structural Faults and Repair 2012, Proceedings in CD-
ROM.
[20] Moropoulou, A., Labropoulos, K. C., Delegou, E. T., Karoglou, M., & Bakolas,
A. (2013). “Non-destructive techniques as a tool for the protection of built
cultural heritage”. Construction and Building Materials, 48, 1222-1239.
[21] Panagiotopoulos, P.D., (1993). Hemivariational Inequalities. Applications in
Mechanics and Engineering. Springer-Verlag, Berlin, New York, (1993).
[22] Park Y.J. and A.H.S. Ang, (1985). Mechanistic seismic damage model for
reinforced concrete, Journal of Structural Division ASCE, vol. 111(4), 722–739.
[23] Paulay T. and M.J.N. Priestley, (1992), “Seismic Design of Reinforced Concrete
and Masonry Buildings”, Wiley, New York.
[24] PEER (2011). Pacific Earthquake Engineering Research Center. PEER Strong
Motion Database. http://peer.berkeley.edu/smcat..
[25] Penelis G. Gr., & Penelis Gr. G. (2014). “Concrete Buildings in Seismic
Regions”. CRC Press.
[26] Priestley, M.J.N., Seible, F.C. and Calvi, G.G. M., (1996). “Seismic Design and
Retrofit of Bridges”. John Wiley & Sons, Inc..
[27] Spyrakos C.C. and Maniatakis Ch.A. (2006). "Retrofitting of a Historic Masonry
Building", 10th National and 4th International Scientific Conference on
Planning, Design, Construction and Renewal in the Construction Industry
(iNDiS 2006), Novi Sad, 22-24 November 2006, 535-544.

[380]
GEOTECHNICAL PROBLEMS
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.13
1
Slobodan ĆORIĆ
Dragoslav RAKIĆ2

FOUNDATION REINFORCEMENT BY MICROPILES

Abstract: Micropiles can be installed, for foundation reinforcement, in almost all types of soil and
ground conditions. They can be vertical or inclined at any angle and may be considered as a substitute
for conventional piles and anchors. They are installed by methods that cause minimal disturbance to
adjacent structures, minimal vibration and noise, too. In according to that, they are very suitable for
foundation reinforcement in urban areas. In the paper are presented procedures for constructing
micropiles and methods for determining their geotechnical bearing capacity and settlement, too. From
2005. micropiles have been successfully constructed in Serbia.

Кey words: micropile, grouting, steel bar/ pipe, geotechnical bearing capacity, settlement.

OJAČANJE TEMELJA POMOĆU MIKROŠIPOVA

Rezime: U cilju ojačanja temelja, mikrošipovi mogu da se grade u svim vrstama tla i različitim terenskim
uslovima. Mogu da budu vertikalni i kosi i stoga se koriste kao zamena za konvencionalne šipove i
ankere. Metode njihovog građenja su takve da izazivaju minimalne poremećaje okolnog tla i susednih
objekata, a postupak izvođenja nije praćen ni vibracijama a ni bukom. Zato su oni posebno pogodni za
primenu u urbanim sredinama. U radu su prikazani izvođenje mikrošipova i proračun geotehničke
nosivosti i sleganja mikrošipova. U Srbiji se mikrošipovi primenjuju od 2005 god.

Ključne reči: mikrošip, injektiranje, čelična šipka/cev, geotehnička nosivost, sleganje.

1
Prof. Ph.D., University of Belgrade, Faculty of Mining and Geology, Đušina 7, 1100 Belgrade,
e-mail: srdjan_05@yahoo.com
2
Ass. Prof. Ph.D., University of Belgrade, Faculty of Mining and Geology, Đušina 7, 1100 Belgrade,
e-mail: dragoslav.rakic@rgf.bg.ac.rs

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1. INTRODUCTION
Micropiles were conceived in Italy 1952. in response to the demand for innovative
techniques for underpinning historic buildings and monuments that had sustained
damage with time and especially during Second World War. After that, micropiles
tehnology was used in the United Kingdom in 1962, in Germany in 1965, in the
United States in 1973, and so on. It has to mention that till sixties these piles were
called “root piles”[1].
The micropile technology was introduced in Serbia in 2005. for constructing
businees building at the corner between Duke Miloš street and Boulevard of King
Aleksandar- at the place of demolished inn “Three leaves of tobacco”. After that
micropiles were used for rebuildings hotel “Metropol” in Belgrade [2] and television
building in Pančevo [3], repairing footings residential house in Veliki Mokri Lug [4]
and so on.

2. MICROPILE CONSTRUCTION
A micropile is a small diameter pile which is constructed by drilling a borehole,
placing reinforcement and grouting the hole. A typical cross sections of micropiles
are shown in Fig.1.

Figure 1 – Typical cross sections of micropiles

A micropile diameter is mostly between 150-300 mm and its length can be several
tenth meters. In Serbia maximum length of micropiles was 15 m.
The grout is cement- water mix with typical water/cement (w/c) ratio in range of
0.40 to 0.50 by weight. Its design compressive strenght after 28 days is between 28
and 35 MPa. Reinforcement may consist of a single reinforcing bar, a group of
reinforcing bars or a steel pipe. Pressure grouting is usually between 1.0 and 5.0 MPa
and a grout tehnique can be in one or two steps. A micropile construction sequence is
illustrated in Fig. 2 [5].
Micropiles can be installed in almost all types of soil and ground conditions. They
can be vertical or inclined at any angle and may be considered as a substitute for
conventional piles and anchors. They are installed by methods that cause minimal
disturbance to adjacent structures. The installation procedure causes minimal

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vibration and noise and can be used in conditions of low headroom (for example: the
weight of drilling equipment is 1,2 t and the height is about 1,0 m) [3].

Figure 2 – Micropile construction sequence

In according to that, they are very suitable for application in urban areas (Fig. 3.).
It has to say that the same type of equipment is used for ground anchors and for
micropiles.

Figure 3 – Micropile applications for footing reinforcement

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Micropiles can mostly withstand axial loads. Their axial ultimate capacity can be
even 3000 kN- 4000 kN. In Serbia have been constructed micropiles with maximum
axial bearing capacity 1200 kN. The special drilling and grouting methods used in
micropile installation allow for high grout/ ground bound values along the grout/
ground interface. The grout transfers the load through friction from the reinforcement
to the ground in the micropile bond zone in a manner similar to that of ground
anchors. The grout/ground bound stenght achieved is influenced primarily by the
ground type and grouting method used.

3. GEOTECHNICAL BEARING CAPACITY OF A MICROPILE

The bearing capacity of micropiles, with the respect to axial loading, consists of
two basic aspects:
 The structural load capacity which depends on area of composite reinforced
micropile and strength of the sections materials
 The geotehnical load capacity which depends on the grout/ground interface
parameters and effects of pressure grouting
In this paper will be estimated geotechnical bearing capacities of micropiles, only.
In determining bearing capacity of micropiles any end-bearing contribution is
generaly neglected and the grout transfers the load through friction along the grout/
ground interface. This is due to the following factors:
 The area for the skin friction is significantly larger then the area for end bearing
 The pile movement needed to mobilize frictional resistance is significantly less
than that needed to mobilize end bearing.

Figure 4 – Geotehnical bearing capacity of a micropile

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Following that, the geotehnical bearing capacity of a micropile (Fig. 4) can be

expressed by following equation [6]:

Qs    Ds  Ls  qs (1)
where:
Qs = Qf - geotehnical bearing capacity
Ds = · D - diameter of grouted cross-section of a micropile
 - coefficient of expanding diameter of a micropile
D - diameter of drill hole
Ls - length of grouted part of a micropile
qs - strenght of interface between grout and ground
The values of coefficient  depend of grout technique and ground conditions i.e.
type of soil and they are shown in Table 1 [6], [7]:
Table 1 – Typical values of coefficient α
grout technique
soil/ rock
IRS* IGU**
gravel 1,6-1,8 1,2-1,4
sand 1,4-1,6 1,1-1,2
silt 1,4-1,6 1,1-1,2
clay 1,6-2,0 1,1-1,2
chalk, marl,
marled 1,8 1,1-12
limestone
rock 1,2 1,1
In Table 1 is: IRS - technique of several phases of grouting with pressure grouting pi
which is higer then Menard`s limit pressure pl i.e. pi ≥ pl
IGU - technique of one phase of grouting with pressure grouting pi as
0.5pl < pi < pl
On the basis of numerous tests determined following diagrams for estimating
interface strength qs [6]. These diagrams depend of soil/ rock type, grout technique
(IRS or IGU) and of SPT- N values and Menard`s limit pressure pl, too (Fig. 5,6,7,8).
The geotehnical bearing capacity of micropile, obtained from equation (1), may be
used for determining bearing capacity of anchors i.e it is valid for axial compression
force and for axial tension force, too.

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Figure 5 – Diagrams for determining qs in sands and gravels

Figure 6 – Diagrams for determining qs in clays and silts

Figure 7 – Diagrams for determining qs in chalk, marl and marled limestone

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Figure 8 – Diagrams for determining qs in weathered and fractured rocks

The allowable bearing capacity of a micropile Qa can be obtained from the

equation
Q
Qa  s (2)
Fs
where:
Fs - factor of safety
The value of Fs is mostly 2.0. [1], [8].
If micropiles are constructed in multi layers soil it has to take in consideration in
the same way as for conventional piles [9].
In addition to above, geotehnical bearing capacity of a micropile can be implicitly
included by increasing shaft capacity about 10 % [10], [11].
It has to emphasize that if the tip of micropile is rested on rock, than it has to
determine end bering capacity of micropile Qp. In that case bearing capacity of a
micropile Qf is:

Q f  Qp  Qs (3)
The Qp has to determine in the same way as for conventional piles [9].

4. SETTLEMENT OF A MICROPILE
The settlement of a micropiles s has the elastic se and plastic sp components [1]
i.e.
s  se  s p (4)

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The elastic displacement of a micropile se can be approximated using the equation

F L
se  (5)
A E

se - elastic component of total displacement

F - applied axial load
L - elastic length of micropile
A·E - axial stiffness of a micropile cross section

The plastic settlenent sp is the consequence of the soil displacement under the
micropile tip. It can be determined during load tests. The plastic displacement will
increase with an increased applied load and will increase with increasing softness of
the soil or decreasing geotehnical bond capacity. In most cases typical plastic
settlement values may vary from 2 mm to 5 mm.
It has to mention that when micropiles are in a group than procedure for evaluating
micropile group plastic settlement is similar to that for conventional piles. The same
is valid for geotechnical bearing capacity, too.

5. CONCLUSION
The application of micropiles for constructing and rebuilding structures is a
contemporary method of foundation. Micropiles may be considered as a substitute for
conventional piles and anchores. They are installed by techniques that cause minimal
disturbance to adjacent structures. The installation procedure causes minimal
vibration and noice and can be used in conditions of low headroom. So they are very
suitable for foundation reinforcement in urban areas.
Since 2005. micropiles have been successfully constructed in Serbia.

REFERENCES
[1] Federal Highway Administration (FHWA). (2005): “Micropile design and
construction reference manual”, Publication no. FHWA NHI-05-039. United
States Dept. of Transportation, Course no. 132078. pp. 456.
[2] Hranisavljević, M., Mandić, D., Kiković, A. (2010): „Micropile in the function
of building strengthening, remediation and founding“, 3 Symposium
Macedonian Asoc. Geotechnics, DGM, pp. 209-216.
[3] Ćorić, S., Mandić, D., Rakić, D. (2008): „Glavni projekat izmene fundiranja
objekta zgrade televizije rtv Pančevo sa geotehničkim izveštajem“,
Dokumentacija rudarsko-geološkog fakulteta, Departmana za geotehniku.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[4] Vujović, I. (2013): „Glavni projekat sanacije temelja stambenog objekta – lamela
3 na kp. 1049/1, Veliki Mokri Lug“, Dokumentacija saobraćajnog instituta CIP.
[5] Frank, R. (2006): “The French national project on micropiles”, 14 th Prague
Geotechnical Lecture, pp. 62.
[6] Bustamante, M., Doix, B. (1985): „Une methode pour le calcul des tirants et des
micropieux injectes“, Bull. Liaison Labo p.et ch., 140, ref. 3047.
[7] Collota, T. (2005): „Geotecnica 3“, Palermo: D. Flaccovio.
[8] Liew, S. S., Fong, C.C. (2003): „Design & construction of micropiles“,
Geotechnical Course for Pile Foundation Design & Construction, Ipoh.
[9] Ćorić, S. (2008): „Geostatički proračuni“, Rudarsko-geološki fakultet Beograd i
časopis „Izgradnja“ str. 460.
[10] Han, J., Ye, S.L. (2006): “A field study on behavior of micropiles in clay under
compression or tension”, Can. Geotech. J. 43.
[11] Tonon, F., Mammino, A. (2004): “Reliability – based design and construction
issues for a micropile foundation in Costa Rica”, Practice Periodical on
Structural Design and Construction, ASCE, vol. 9. no.4

[390]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.13
1
Milan ULJAREVIĆ
Slobodan ŠUPIĆ2

GEOTECHNICAL FOUNDATION DESIGN OF BRIDGE

"UNDERPASS LUG"
Abstract: The paper presents the results of the ground investigation and assessment of the ground
conditions in order to design underpass "Lug" foundation. The works were carried out within the project
design of highway Banja Luka - Doboj. Underpass Lug enables a crossing of the highway across the
existing local road. The purpose of the present investigation was the determination of the ground
conditions (stratigraphy, ground water, subsoil characteristics) at the position where the underpass is to
be constructed. After assessing the ground conditions, the values of the ground parameters were
determined in order to design its foundation (ground strength parameters, bearing capacity, settlements).
Finally, based on the deducted ground parameters, geotechnical calculations are carried out and
subsequently, proposals regarding the type of the foundation are made.

Кey words: underpass, foundation, geotechnical investigation, ground conditions, bearing capacity.

GEOTEHNIČKO PROJEKTOVANJE TEMELJA PODVOŽNJAKA

"LUG"
Rezime: U radu su prikazani rezultati ispitivanja tla i ocena terenskih uslova u cilju projektovanja
temelja podvožnjaka "Lug". Radovi su vršeni u okviru izrade projekta Autoputa Banja Luka – Doboj.
Podvožnjak Lug omogućava prelaz Autoputa Banja Luka – Doboj, na deonici Banja Luka - Prnjavor,
preko postojećeg magistralnog puta. Cilj ovog istraživanja bio je utvrđivanje kopnenih uslova tla
(stratigrafija, podzemne vode, karakteristike tla) na poziciji gde pomenuti podvožnjak treba da bude
izgrađen. Nakon procene uslova tla, određene su vrednosti parametara tla (parametri čvrstoće tla,
nosivost tla, sleganja). Na kraju, na osnovu utvrđenih parametara tla, urađeni su geotehnički proračuni i
dati predlozi za vrstu temelja.

Ključne reči: podvožnjak, temelj, geotehničko ispitivanje, uslovi tla, nosivost.

1
PhD Student, MSc CE, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering
and Geodesy, e-mail: umilan89@gmail.com
2
Ass. MSc CE, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering
and Geodesy, e-mail: ssupic@uns.ac.rs

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1. INTRODUCTION
The scope of the present report is to present the results of the ground investigation,
which was carried out in the understudy area and assess the ground conditions in
order to design underpass "Lug" foundation. The present investigation included
determination of the ground conditions (stratigraphy, ground water, subsoil
characteristics) at the position where the mentioned underpass is to be constructed.
After assessing the ground conditions, the values of the ground parameters were
determined in order to design its foundation (ground strength parameters, bearing
capacity, settlements). Finally, based on the deducted ground parameters,
geotechnical calculations are carried out and subsequently, proposals regarding the
type of the foundation are made.
The bridge is located on the highway Banja Luka - Doboj, section Banja Luka -
Prnjavor, at chainage 4+325.00km of the highway’s axis. The location is presented in
the plan view extract of Figure 1. The box’s dimensions are length x width = 30.00m
x 10.30m. Cross section of structure is a frame structure with 8.70m of clear width
and 5.70m of clear height. Independent wing walls with length of 9.00 to 9.20 m and
height of 7.20m are located at the entrance and exit of the structure [1].

Figure 1 – Plan view extract with barehole location

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2. GROUND INVESTIGATION
According to the geological report, the geology of the area consists of alluvial
sediments in the form of river terraces Vrbas (t). More specifically, these sediments
consist of gravel with layers of sand and clay.
2.1. Ground investigation - Fieldwork
According to geotechnical reports, in the understudy area one borehole (ΒΟ-154)
was drilled, in September 2009. The depth of BO-12 borehole was 10.0m. The
boreholes location is presented in the extract of the plan view of the area in Figure 1.
In the following Table 1, boreholes’ co-ordinates, depths, elevations, and the ground
water level are given.
Table 1 - Borehole location, depth and ground water level
Depth Co-ordinates Elevation
Barehole Depth of ground
(name) (m) X Y Z(m) water (m)

BP-154 10 6446436.76 4975055.01 122.06 5.50

2.2. Ground investigation - Laboratory testing

Based on geotechnical reports, in borehole BO-154, a program of ground
engineering laboratory tests was carried out, on selected samples. The program
included the following:
 Soil Classification tests - measurement of natural characteristics (particle size
analysis, Atterberg limits, moisture content, bulk density and specific gravity),
 Mechanical Soil properties - measurement of soil mechanical characteristics
(unconfined compressive strength test, and one-dimensional consolidation test).
2.3. Subsoil stratigraphy
According to the results of the ground investigation, the stratigraphy of the area
consists of:
 Superficially and to a depth of 0.80m, humus is encountered.
 From the depth of 0.80m to a depth of 2.00m, the ground consists of brownish
yellow silty SAND to sandy SILT (SM/ML).
 From the depth of 2.00m to a depth of 3.00m, brownish - yellow lean CLAY
with sand, hard, with intermediate plasticity is found (CL).
 From the depth of 3.00m to a depth of 10.0m where the borehole is terminated,
the ground consists of brownish - yellow GRAVEL poorly graded, partly with
silt, very dense (GP).
During the execution of borehole BO-154 in September 2009, ground water was
encountered at 5.50m. The geotechnical parameters of the ground layers are taken
directly from the results of the laboratory tests and indirectly from correlations
dictated by international literature. The typical ground model of the area where the

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culvert is to be constructed, is displayed in Figure 2. This model is then used to carry

out geotechnical checks and to form proposals regarding the foundation of the culvert.

Figure 2 – Typical ground model

Based on the aforementioned, the geotechnical longitudinal cross section is
presented in Figure 3.

Figure 3 – The geotechnical longitudinal cross – Underpass Lug

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3. GEOTECHNICAL EXAMINATION – PROPOSAL

3.1. Foundation depth and allowable bearing pressure
The underpass, as presented in the structural design, is to be founded at a
minimum depth of approximately 2.0m. At this depth, the ground consists of
Brownish - yellow lean CLAY with sand.
Given the consistency of the ground as well as the form of the structure, the use of
a raft foundation (reinforced concrete slab) is proposed.
The allowable bearing pressure against ground failure is calculated according to
JUS for rectangular foundations, with a minimum foundation depth of D=1.5m from
the ground surface.
The adopted geotechnical model is used for the calculations, with the assumption
of founding the structure on Brownish - yellow lean CLAY with sand, which is
encountered from the depth of ~2.0m to the depth of ~3.0m as shown in Typical
Ground Model. For the calculations it is assumed that the structure is founded on a
cohesive stratum, overlaying a granular stratum of infinite depth, with undrained
shear strength Cu≈120kPa.
For a foundation of sizing according to the structural design, without horizontal
loading, the allowable bearing pressure is calculated to be σ επ≈118kPa and
respectively smaller under the condition of horizontal loads applied.
In the case of seismic loading, the value of the allowable bearing pressure is
calculated to be σεπ≈361kPa.
The allowable bearing pressure and the results for static and seizmic load are
presented in Figure 4.

Figure 4 – Ultimate bearing capacity for static and seizmic loads (B' – effective foundation
width, H – horizontal load)

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3.2. Settlement calculations – Soil stiffness

For a single pad, the settlement Δh at its foundation can be estimated based on the
approximate elasticity equations.
For the foundation of the structure, the following parametric values are assumed
σf=50kN/m2 to 250kN/m2, Β=8.0÷12.0m and constant ratio L/B=2.6 with a minimum
foundation depth of D=1.5m (the values of σf are used with a factor of safety of 1.0
over the dead and live loads of the superstructure due to the fact that the settlement
check is carried out on serviceability limit state). The results of the settlement check
for a rectangular foundation are presented in Figure 5.
The resulting settlement values are in the order 3cm approximately for a
foundation pressure of σf≈100kN/m2. The value of the index of soil stiffness
Κ=σf/Δh, under static conditions and for a foundation’s width of B≈11.0m, is
estimated to be in the order of 3.5kN/m3. It is assumed that the structure is founded on
soil exhibiting elastic behavior.This value is valid when the consolidation settlements
are completed (i.e., for dead and typical live loads, in long-term loading conditions).
In the case of seismic loading, the value of K can be assumed to be equal to three
times the aforementioned value.
In conclusion, the total settlement of the structure, if the actual average imposed
load to the foundation is in the range of 100 KN/m2, is considered to be acceptable.

Figure 5 – Settlements for a rectangular foundation

4. CONCLUSION
Based on the results of the ground investigation, the subsoil in the area where the
culvert is to be constructed consists of CLAY with sand overlaying clayey GRAVEL
with sand.

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As for the type of foundation, the use of a raft foundation (reinforced concrete
slab) is proposed as the best solution.
The allowable bearing pressure (according to JUS) is estimated (without
horizontal loading) to be equal to 118kPa.
The induced settlements are calculated and are considered to be acceptable
(≈3.0cm). The index of soil stiffness is also estimated for static loading under the
assumption that the structure is founded on elastic ground.
Due to the presence of underground water (≈5.50m depth), pumping might be
required, if the excavation takes place during winter or spring time. Therefore, it is
proposed to start the foundation works in summer time.

ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

REFERENCES
[1] Highway Banja Luкa - Doboj, section: Prnjavor - Doboj, final geotechnical
foundation design of bridge "Underpass Lug'', Public Company 'Motorways'
Banja Luka

[397]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 624.13
1
Nenad ŠUŠIĆ
Dušan BERISAVLJEVIĆ2
Marko PRICA3
Ksenija DJOKOVIĆ4

DLT-TEST: DETERMINING PILE BEARING CAPACITY

USING A DYNAMIC METHOD
Abstract: Over the past several years, the use of DLT method for determining pile load-bearing capacity
has been intensified both globally and domestically, as an alternative to static load tests. The main
advantage of the DLT over static tests is reflected in the fact that it saves both time and money. The
paper presents theoretical bases of the DLT method as well as the manner of its application in-situ. In
conclusion, the paper offers an analysis of results and a procedure for determining bearing capacity of
piles, using the DLT method.

Кey words: pile, bearing capacity, dynamic method, principles, stress waves, weights, sensors.

DLT-TEST: ODREĐIVANJE NOSIVOSTI ŠIPA DINAMIČKOM

METODOM
Rezime: Poslednjih nekoliko godina u svetu i u našoj zemlji DLT metoda intenzivno se koristi za
određivanje nosivosti šipova kao alternativa statičkom probnom opterećenju. Glavna prednost DLT
metode u odnosu na statičku je ušteda u novcu i vremenu. U radu će se prikazati teoretske osnove DLT
metode, način izvodjenja testa na terenu. U zaključku će se dati analiza rezultata i postupak odredjivanja
nosivosti šipa DLT metodom.

Ključne reči: šip, nosivost, dinamička metoda, principi, naponski talasi, tegovi, senzori.

1
PhD, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, nenad.susic@institutims.rs
2
MSc, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, dusan.berisavljevic@institutims.rs
3
BSc, IMS Institute, Bulevar vojovde Mišića 43, Belgrade, marko.prica@institutims.rs
4
MSc, IMS Institute, Bulevar vojvode Mišića 43, Belgrade, ksenija.djokovic@institutims.rs

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1. THEORETICAL GROUNDS OF THE METHOD

Over the past several years, the DLT method has been intensively used in our
county for determining bearing capacity of piles as an alternative to the static load
test. The main advantage of the DLT method over the static one is that is saves money
and time to the Investor who does not have to secure a pricey counter weight.
With the DLT method, a generated stress wave, caused by a falling weight causes
substantial specific deformities within the pile that could be measured from its
surface. By continually measuring deformity () and acceleration (a) in time (t) it is
possible to calculate forces and speeds within the pile. The force is a product of
deformity, dynamic modulus of elasticity (E) and surface of the pile’s cross section at
the measurement level (A), equation 1.

F=EA (1)

Deformity is measured with two extensometers and measurements thus taken are
further used to calculate two forces, namely, F1 and F2 and the corresponding median
force: F=(F1+F2)/2.
By integrating acceleration in time (t), we obtain the speed of movement of the
pile (v) at the measurement level, equation 2.

v=adt (2)

DLT KW22-43
Force and Velocity x Impedance ( Blow Number: 11 )
Force Velocity x Impedance
5

2
Force[MN]

-1

-2

0 10 20 30 40 50 60 70 80 90
Time [ms]
PDA-DLT 8.1.18

Figure 1. Measured signals of force and speed x impedance in time

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Acceleration is measured using two accelerometers and thus taken measurements

are used to calculate velocities v1 and v2 and the corresponding median velocity
v=(v1+v2)/2.
By integrating the resulting median velocity we obtain the value of movement of
the pile in time.
The grounds for analyzing results of dynamic tests performed on piles are the
force signal (F) and speeds multiplied by pile impedance (v x Z), Figure 1. All data
(pile stresses, bearing capacity…) are obtained based on these two signals.
Theoretical assumptions of wave mechanics indicate that the force acting upon
cross section of the rod (pile) is proportional to the speed of movement of the
observed part of the pile and the proportionality constant is represented by pile
impedance (Z), equation 3.

F=Zxv (3)

Impedance can be calculated using equation 3. From Figure 1, it is obvious that in

the beginning, the signals are identical (overlapping) and they remain to be such as
long as there are no reflections from surrounding soil or from discontinuities within
the pile. After the starting segment, signals start to separate and the relative distance
between them indicates the magnitude of mobilized friction along the pile casing. A
larger distance indicates the bigger “contribution” of friction along the pile casing to
the overall bearing capacity of the pile.
Different methods are used to determine bearing capacity based on measured
signals, and they can be either direct or indirect.
Direct methods provide for in-situ determination of static resistance of soil, from
measured accelerations (speeds) and deformities (forces) at the time of pile driving.
CASE, Impedance and TNO methods are among the most frequently used direct
methods, 1. Direct methods are applied under the assumption: that the pile is of
uniform cross section, that the material the pile is made of is linearly elastic and that
stress wave propagation is one dimensional (1-D). Te assumption that the cross
section of the pile is uniform poses an obstacle to the application of direct methods
for determining bearing capacity of bored piles since their cross sections are often not
uniform. Direct methods are therefore broadly used only with precast concrete and
steel piles. Bored piles call for the use of an indirect method, the so called “Signal
Matching“ (SM) procedure which can include in calculations different dimensions of
cross sections within the same pile.
The Signal Matching is a procedure involving computerized search for signals
which best match the measured one. This method requires previous adoption of the
appropriate model of pile and soil. The measured signal of force is set up in the
software as the starting condition at the pile top (position of the sensors) and, taking

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into account the formed model of the pile and soil, the search starts for the signal
which best matches the measured one.
A special advantage of the SM procedure relative to direct methods is its
possibility to simulate a static load test. This makes it possible to draw up a graphic
display of settlement depending on load for the base (toe) as well as for the casing of
the pile. Thus obtained dependency can be compared to dependency obtained from
the static test load. This enables calibration of the parameters of soil used in the SM
procedure thus raising significantly its reliability and making it possible to use such
parameters for other piles driven into similar soils.

2. APPLYING TEST LOAD

Dynamic testing implies applying several dynamic blows of the falling load-
weight (Figure 2) onto the pile while measuring and controlling parameters indicating
the quality of blows and magnitude of stress generated in the pile. By falling onto the
pile, the weight induces a stress wave, and accelerations and deformities within the
pile caused by thus generated wave are registered by accelerometers and
extensometers positioned at the distance of 1.5 to 2.5 diameters from the top of the
pile, Figure 3. At least two pairs of accelerometers and extensometers are required for
testing, positioned diametrically opposite relative to the pile axis in order to be able to
control blow eccentricity. Thus measured deformities and accelerations serve for
calculation of force and speed in the function of time, constituting the grounds for
interpretation.

Load lifting/releasing
hydraulic system

Weight W=10 t

Hardwood cushion

Base plate 1000mm

Figure 2.Disposition of dynamic pile testing  1.2 m, length L=14.0 m

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

Choosing appropriate weights is of essential importance for successful testing of

bored piles [2]. Weight, falling height and details pertaining to materials to be placed
between the weight and the pile should be determined in such a way to enable the
weight blow to cause sufficient movement (penetration) of the pile to mobilize the
required resistance of soil without allowing the stresses generated by blows to exceed
the value of compressive and tensile strength of the pile. The height from which the
weight is dropped varies from 0.3m to 3.0m. Heavier hammers require lower heights
and vice versa. Hussein et al. [2] simulated a dynamic load test on bored piles of
different diameters using GRLWEAP software, based on which they gave a general
recommendation that the weight should weigh 1.5% of the static bearing capacity that
needs to be proven through testing.
Piles can be prepared for testing in several ways, and the aim is to enable
positioning of the sensors to the pile shaft at the sufficient distance from the top and
to ensure that the weight is positioned centrally relative to the pile axis. If the piles to
be tested are pre-identified, each pile shaft should be executed 2-3 pile diameters
lengthier relative to the planned length and then cropped (0.5m, for inst.), to ensure
best possible quality of concrete at the top. This is followed by excavation to the
depth equal to the value of 2-3 diameters of the pile and by placement of sensors to
the pile shaft. The other way is best for piles of non-uniform cross section and
concrete mixtures the quality of which varies along the pile length (for inst. bored
piles with bentonite suspension), and it implies also execution of an extension on top
of the pile head, Figure 4.

Acceleration and
strain sensors

Figure 3. Pile acceleration and strain sensor

Concrete extension should be strengthened by internal reinforcement or external

casing in the form of a thin steel pipe. Sensors are attached directly to the concrete (if
there is a steel pipe, square shaped openings should be made with sides measuring
approximately 200m).

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The surface receiving the weight should be flat, smooth and perpendicular to the
pile axis to ensure an optimum transfer of energy from the weight to the pile.
Particular attention should be paid to the place for placing extensometers, taking into
account that measured deformities are larger in poor quality concretes, which has
direct impact on test results.

Figure 4. AB extension in casing in the execution phase (left) and after concreting (right)

3. AN EXAMPLE OF DETERMINING PILE BEARING CAPACITY WITH

THE APPICATION OF DLT METHOD
The following is an example of determining bearing capacity of a pile which is
part of a bridge pillar foundation. The bridge is at the route of a highway currently
under construction. With respect to execution technology, it is a reinforced concrete
bored pile L=14.0 m in length,  1.2 m in diameter. The test was carried out with the
application of a 10.000 kg weight.
Measured signals of force (F) and velocity (v) for both sensors are presented in
Figure 5. The presented signals are of excellent quality and centricity. In practice,
signals of quality better than of those presented here are rarely obtained.
Diagram F and vxZ presented in Figure 6 is a combination of signals given in
Figure 5 with introduced proportionality constant (Z).
From the diagram, one can see the sudden increase in velocity at the level of the
base (toe) of the pile, indicating that the reflected (tension wave) bears the opposite
sign relative to the wave (compression) generated by weight blow. This is more
clearly visible from the Figure 7 chart showing the change of force in time for the
wave moving up (upward wave). In the beginning, force grows as a consequence of
mobilizing friction along the casing, only to experience a sudden
drop in the face of the upcoming, reflected wave. Further on, the signal is subject
to the joint impact of forces coming from the base (toe) and casing of the pile. The
permanent pile set for the analyzed weight blow amounts to 2.6mm, which might
indicate that the limit bearing capacity of the pile has been mobilized.

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Pile Driving Analysis

Pile Driving Analysis Velocity 1 & 2 as function of time ( Blow Number: 6 )
Force 1 & 2 as function of time ( Blow Number: 6 ) Velocity 1 Velocity 2
Force 1 Force 2 1,2

14 1,0

12 0,8

10 0,6

Velocity[m/s]
8 0,4
Force[MN]

6 0,2

4
0,0

2
-0,2
0
-0,4
-2
-0,6

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
Time [ms] Time [ms]
PDA-DLT 8.1.18 PDA-DLT 8.1.18

Figure 5. recordings of F and v in time

Pile Driving Analysis

Force and Velocity x Impedance ( Blow Number: 6 )
Force Velocity x Impedance
14

12

10

6
Force[MN]

-2

-4

-6

0 10 20 30 40 50 60 70 80 90 100
Time [ms]
PDA-DLT 8.1.18

Figure 6. F and vxZ in time

Pile Driving Analysis

Upward force wav e as function of time ( Blow Number: 6 )

-1
Force[MN]

-2

-3

-4

-5

-6

-7

0 10 20 30 40 50 60 70 80 90 100
Time [ms]
PDA-DLT 8.1.18

Figure 7. Force in the function of time for the upward wave

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Figure 8. Diagram of pile head movements, depending on load

Thus obtained signals were used in an SM procedure to determine bearing

capacity of the pile and dependency of pile top setting on load, Figure 8.
By interpreting the results, it was established that the limit bearing capacity of the
pile was 4376 kN, with the bearing capacity of the base being 1357 kN (31 %), and
that of the shaft, 3019 kN (69 %).
When testing piles with the application of a DLT method, one should make sure
not to exceed allowable compressive and tensile stresses within the pile. In this
example, tensile stresses amount to -3 MPa, and compressive stresses to 13 MPa
which is below the values of allowable stresses for reinforced concrete used for bored
piles. Other data can be obtained using a DLT method as well (dynamic resistance,
weight efficiency, etc.), but these are of minor practical significance to the Investor
who pays most attention to the data on limit values of bearing capacity of piles.

4. REFERENCES
[1] German Society for Geotechnique. Recommendations for Static and Dynamic
Pile tests
[2] Hussein M.H., Likins G. E., Rausche F. (1996). Selection of a Hammer for High-
Strain Dynamic Testing of Cast-in-Place Shafts. Proc. of the Fifth International
Conference on the Application of Stress-wave Theory to Piles, FL, 759-772
[3] TNO-Report. (1996). TNOWAVE, Dynamic Load Testing Signal Matching,
Users Manual
[4] Smith E.A.L. (1960). Pile driving analysis by wave equation. Journal of the Soil
mechanics and Foundation division, ASCE, vol 80, str. 1145-1171

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MANAGEMENT IN DESIGN METHODS
AND CONSTRUCTION
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.055
1
Jasmina DRAŽIĆ
Aleksandra VUJKOV2
Norbert HARMATI3

THE MULTI-CRITERIA OPTIMISATION METHOD IN SELECTING

A WALL STRUCTURE BETWEEN TWO FLATS
Abstract: The paper considers the problem of selecting the optimal solution for a wall structure between
two flats. The evaluation of the selected five variants of walls encompasses several criteria: costs,
construction time, weight, and sound insulation. The output results in the form of a ranking list with the
overview of optimal solutions for the wall between two flats are calculated using the multi-criteria
optimisation method. The influence of the optimisation criteria on the selection of the final solution is
also analysed.

Кey words: walls, construction, costs, time, weight, sound insulation, multi-criteria optimisation

METODA VIŠEKRITERIJUMSKE OPTIMIZACIJE U IZBORU ZIDA

IZMEĐU DVA STANA
Rezime: U radu je razmatran problem izbora optimalnog tipa zida između dva stana. Vrednovanje
izabranih pet varijanti zidova obuhvatilo je više kriterijuma: troškove, vreme izrade zida, težinu i zvučnu
izolaciju. Primenom metode višekriterijmske optimizacije, dobijeni su izlazni rezultati, rang lista
najpovoljnijeg rešenja zida između dva stana. Analiziran je i uticaj kriterijuma optimizacije na izbor
konačnog rešenja.

Ključne reči: zidovi, izvođenje, troškovi, vreme, težina, zvučna izolacija, višekriterijumska optimizacija

1
Prof., PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy
dramina@uns.ac.rs
2
M.Civ.Eng., University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, vujkovaleksandra@yahoo.com
3
Ass. PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, harmati@uns.ac.rs

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1. INTRODUCTION
Walls, as an integral element of each building, represent a solid structure that,
depending on its purpose, function and position in an object, can play an important
role in the load distribution, partitioning, heat control, coldness control, passage
design, sound insulation, etc. Well-designed and well-constructed walls will primarily
fulfil their primary function, and then, depending on the applied materials and
finishes, can also contribute to a more beautiful and interesting interior (exterior)
impression.
This paper analyses different types of walls that can be placed between two flats,
as well as the selection of the most optimal type of the wall. Apart from the criteria
related to the construction of walls (costs, time), the positioning of the wall between
two flats requires that the solutions related to the sound insulation and the effective
regulation defining this area are to be considered in the analysis. Depending on the
design solution, these walls may be directly or indirectly included in the structural
assembly; hence, the choice of the appropriate material (weight) can contribute to a
more rational structure, and consequently more economical solution for the entire
building. Due to the large number of different construction materials that can be used,
as well as the requirements that those walls have to satisfy, the problem of selecting
the best variant of the wall can be solved as a problem of multi-criteria optimisation,
where the solution implies the inclusion of adequate methods.
For the selection of the optimal alternative for the wall between two flats, the
following walls were analysed: brick wall, hollow block wall, plasterboard wall,
concrete block wall, and reinforced concrete wall. The criteria for evaluation are
reduced to: costs, construction time, weight, and sound insulation.

2. SOUND INSULATION
The materialisation of walls inside a building is determined by the function of the
wall within the building, basic structural requirements, as well as the requirements of
statics and seismics. In addition to these key requirements, it is necessary to consider
the requirements of acoustics in the area of sound insulation when defining the
structure of the wall between two flats.
The right solution for the sound insulation of walls contributes to the improvement
of noise reduction. For sound insulation, it is very important which material is to be
used for the wall (i.e. partitions), as well as the overall system of building elements in
a room. The wall thickness also affects the value of sound insulation. A higher level
of sound insulation can be achieved by selecting the wall with a greater mass.
In this paper, the criterion for sound insulation is observed as a limiting factor in
selecting the alternative variants. Providing the minimal values of insulation
properties that have to be fulfilled for different types of walls is the main criterion for
determining the sound insulation. In order to accomplish the potential requirements

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for premises and facilities in the future, achieving higher values of sound insulation is
a recommendation. Technical requirements for the design and construction of
buildings in the area of acoustics are determined by the standard SRPS U.J6.201,
which proposes the minimal values of sound insulation in buildings and the maximum
allowed sound level of impact that has to be met. This standard defines the
requirements in terms of value that needs to be satisfied when designing walls (i.e.
partitioning) in buildings intended for human residence. The minimum value of sound
insulation for a wall between two flats is prescribed to be 52 dB.

3. VARIANT SOLUTIONS FOR WALLS

Five variants for walls between two flats are considered. For each variant, there is
a short description of materials used and the construction method applied.
Brick walls are built following the rules for masonry, so the bricks are stacked in
horizontal layers and connected to one another by mortar. Such a wall, properly
constructed, in the selected manner, is a stable wall. The brick wall (Variant 1) is
shown in Table 1.
Table 1. Variant 1
VARIANT 1 Brick Wall

Brick wall is assembled of full

bricks (dimensions 25x12x6.5cm).
The wall is plastered on both sides
in cement-lime mortar (1:2:6) 2cm
thick.

Building the wall of hollow blocks is performed in stages. Prior to building the
wall, it is necessary to level the floor base using mortar which corresponds to the
dimension of the wall, at least 1 cm thick. The blocks are placed on the levelled layer
of mortar, so that they are joined to one another using the tongue-groove system. The
second row of blocks continues with the normal masonry bond with a minimum
overlap of 30%. Variant 2 – the wall of hollow blocks – is shown in Table 2.
Table 2. Variant 2
VARIANT 2 Hollow Block Wall

Wall of hollow blocks is built by

POROTHERM blocks (dimensions
20x37.5x23.8 cm). Both sides are
plastered in cement-lime mortar
(1:2:6) 2cm thick.

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The plasterboard walls are made of the substructure (horizontal and vertical
galvanised steel profiles) and plasterboard cladding. Plasterboards are available in a
range of sizes and thicknesses, with two sides in grooves, and the other two with
tongues used for joining. In order to obtain a monolithic wall, proper construction of
joints has to be taken care of. Special glue is utilized for connecting the plasterboards,
consisting of plaster, synthetic binders and additives that increase the hardness and
stickiness. Variant 3 – the plasterboard wall – is presented in Table 3.

Table 3. Variant 3
VARIANT 3 Plasterboard Wall

Wall of plasterboards is made of

A13 boards 1.25cm thick.
Horizontal (UW) and vertical (CW)
girders, 75mm long and 0.6mm
thick, are made of galvanised steel
profiles. Knauf KR SK rockwool,
5cm thick, is placed between
plasterboards and has a role in
improving the sound and thermal
insulation.

Building the wall of concrete blocks begins by placing the first row of blocks on
the cement-lime mortar of a drier consistency 1-3 cm thick. Mortar made in the ratio
of 1:2:6 (cement:lime:sand) is poured over the previously set hydraulic insulation.
The second row continues by placing blocks with shear connectors shifted for the half
block’s length. Variant 4 – the concrete block wall – is shown in Table 4.

Table 4. Variant 4
VARIANT 4 Concrete Block Wall

Wall of concrete blocks is built of

concrete (YTONG) blocks (dimensions
25x20x62.6cm) in Ytong thin-layer
mortar. Both sides are plastered.

Reinforced concrete wall is cast in-situ, as a monolithic structure, by setting the

framework, placing reinforcing bars, and pouring fresh concrete. The quality of
reinforced concrete walls depends on the properties of components in the concrete,
their proportion in the concrete mass mix, their production and transportation, the

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construction, as well as the care of the cast concrete element. In order to achieve a
better quality of construction, the concrete is compacted either by the use of vibrators
or by centrifugation. Variant 5 – the reinforced concrete wall – is presented in Table
5.
Table 5. Variant 5
VARIANT 5 Reinforced Concrete Wall

Reinforced concrete wall is cast by

using reinforced concrete 14cm
thick. Both sides are plastered with
2cm thick mortar.

4. OPTIMISATION CRITERIA
The analysis of evaluation and optimisation encompasses four criteria: wall
construction costs, wall construction time, weight of the wall, and the indicator of
sound insulation for the wall. The values for all five wall variants are presented in
Table 6.
First two criteria represent the indicators of construction efficiency, since the
appropriate selection of materials and the construction type, as well as the reduction
of individual costs and time (cost and time required for wall construction), can
influence the total cost and time period for the construction of a building. Third
criterion (wall’s weight) is important in the analysis and calculation of structural
elements. Selecting the appropriate elements (walls) of a lesser weight contributes to
the more rational solution of construction and the entire building. The sound
insulation indicator for a wall is a criterion that the wall between two flats has to
satisfy in accordance with the regulations (standards) dealing with the sound
insulation issues.
Cost calculation and the time required for wall construction are based on the
norms in civil engineering [1]. For materials and the procedures of construction that
are not included in the standards, empirical data from contractors is used. Prices of
materials are taken from the building material manufacturers. The material price
includes the transportation costs to and on the building site [2].
The time required for wall construction is calculated in hours for each variant. The
values shown imply that every labourer performs one activity; hence there are no
parallel activities [2].
The total net weight of structural and non-structural elements is included into the
analysis of load when structural elements are calculated. Wall thickness, mortar
thickness on both sides and the supplementary elements affecting the weight gain

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(insulation, reinforcing bars, steel sections, etc.) are considered when determining the
final value of the weight of the suggested wall variants.
The value of sound insulation for the brick wall plastered on both sides is 52 dB
[3] and the value of sound insulation for the concrete block wall is 52dB [4]. For the
calculation of sound insulation for the hollow block wall, reinforced concrete wall
and plasterboard wall, the software for calculating the sound insulation, Knauf Sound
Insulation, is used [5]. By entering the basic data into the program (type of the
element, material, purpose and dimensions of the room in which the selected element
is located), the output results are obtained in a report. In addition to the basic
information, the report consists of the results of calculation and diagrams, tables with
values for sound insulation Rw, as well as the criteria in accordance with the standard
SRPS U.J6.201.

Table 6. The values of cost, time, weight and sound insulation for walls
COSTS TIME WEIGHT SOUND INSUL.
[RSD/m2] [h/ m2] [kN/m2] [dB]
VARIANT 1 6668.35 3.68 3.28 52
VARIANT 2 3263.90 1.85 1.29 59
VARIANT 3 2461.03 1.17 0.42 54
VARIANT 4 4814.00 1.49 2.27 52
VARIANT 5 5580.21 3.27 4.00 60

In this paper, the best (most optimal) solution for the wall is selected from the five
variants described. Each wall variant is evaluated according to four criterion
functions. Model optimisation, the vector criterion function, minimises all four
individual criterion functions, and is thus given as
min F(x)= min (f1,f2,f3,f4), (1)
where
f1 is the cost for wall construction [RSD/m²];
f2 is the time required for wall construction [h];
f3 is the weight of the wall [kN/m²];
f4 is the indicator of sound insulation, f4=Pz=1/Rw, (2)
where
Rw is the sound insulation of a wall (dB).
The selection of the most optimal type of the wall between two flats is calculated
using the methods of multi-criteria optimisation, compromise programming and
compromise ranking [6, 7]. Three analyses are performed:
 Analysis I – in the process of optimisation, all criteria have equal weight (the
same weight coefficients);
 Analysis II – priority is attributed to the cost and the time required for wall
construction; and
 Analysis III – priority is attributed to the sound insulation indicator.

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Output results are demonstrated in Tables 7, 8, 9 and 10.

Table 7. ANALYSIS I – Compromise Programming Method

V1 V2 V3 V4 V5
p=1 5 1 2 3 4
p=2 5 1 2 3 4
p=∞ 5 1 2 3 4
p=1 - the solution is the best by all criteria considered together
p=2 - the solution is geometrically closest to the ideal point
p=∞ - priority is attributed to the criterion with the highest deviation

Table 8. ANALYSIS I – Compromise Ranking Method with the Same Weight Coefficients
V1 V2 V3 V4 V5
v=0.0 5 1 2 3 4
v=0.3 5 1 2 3 4
v=0.6 5 1 2 3 4
v=0.9 5 1 2 3 4
v=1.0 5 1 2 3 4

Table 9. ANALYSIS II – Compromise Ranking Method with Different Weight Coefficients

(w1=w2=0.4, w3=w4=0.1)
V1 V2 V3 V4 V5
v=0.0 5 2 1 3 4
v=0.3 5 2 1 3 4
v=0.6 5 2 1 3 4
v=0.9 5 2 1 3 4
v=1.0 5 2 1 3 4

Table 10. ANALISYS III – Compromise Ranking Method with Different Weight Coefficients
(w1=w2=w3=0.2, w4=0.4)
V1 V2 V3 V4 V5
v=0.0 5 1 3 4 2
v=0.3 5 1 3 4 2
v=0.6 5 1 3 4 2
v=0.9 5 1 2 4 3
v=1.0 5 1 2 4 3

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Based on the calculation results (the order of variant solutions), the following can
be concluded:
 In the case of equal treatment of all criteria, the hollow block wall is the best
(optimal) solution – (ANALYSIS I),
 When advantage is attributed to costs and time required for wall construction, the
plasterboard wall is the best (optimal) solution – (ANALYSIS II),
 When advantage is provided for the indicator of sound insulation, the hollow
block wall is the best (optimal) solution - (ANALYSIS III).

5. CONSLUSION
The paper analyses different types of walls that can be placed between two flats,
and the optimal type of wall is selected. Five variants for walls with different
materials, most frequently used in construction today, are described. The alternatives
were: brick wall, hollow block wall, plasterboard wall, concrete block wall, and
reinforced concrete wall. For each of these variants, a brief description of materials
and construction procedures is provided.
Walls are evaluated according to several different aspects on the basis of cost, time
required for wall construction, weight and sound insulation.
The results are calculated using the methods of multi-criteria optimisation,
compromise programming and compromise ranking, and a ranking list is made with
the overview of the most optimal solution for the wall between two flats. Ranking,
according to the analysis in which all criteria are treated equally and when the
advantage is provided to the indicator of sound insulation, demonstrates priority to the
hollow block wall. In the analysis where the advantage is attributed to the criteria of
construction efficiency (construction cost and time), the plasterboard wall is
recommended as the optimal solution. Applying the suggested optimisation methods
offers the possibility to select the optimal solution, i.e. the best variant for the wall
between two flats, in accordance with the set aim of optimisation.

ACKNOWLEDGMENTS
The work reported in this paper is a part of the investigation within the research project
„Development and aplication of contemporary procedures for design, construction and
maintance of buildings“ supported by the Department for Civil Engineering and Geodesy,
Faculty of Technical Sciences in Novi Sad. This support is gratefully acknowledged .

REFERENCES
[1] "Normativi i standardi rada u građevinarstvu - visokogradnja", Civil Engineering
book, Belgrade, 2004.
[2] Vujkov, A.: Master’s Thesis, Faculty of Technical Sciences, Novi Sad, 2015.

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[3] Veršić,Z.: “Tehnička regulativa gradnje - zaštita od buke u zgradarstvu, zvučna

izolacija pregradnih zidova”, Polytechnic of Zagreb, Deparmant of Civil
Engineering, Zagreb
[4] http://www.ytong.rs/
[5] http://www.knauf.rs/
[6] Opricović, S.: "Optimizacija sistema", Faculty of Civil Engineering, Belgrade,
1992.
[7] Opricović, S.: "Višekriterijumska optimizacija sistema u građevinarstvu",
Faculty of Civil Engineering , University of Belgrade, Belgrade, 1998.

[415]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.055
Erika MALEŠEVIĆ

ABC COST ALLOCATION METHOD IN THE CONSTRUCTION

PROCESS
Abstract: ABC (Activity-Based Costing) method of cost accounting is based on the methodology for
measuring costs and performance of activities, resources and facility costs, thereby joining resources to
activities while the activities are joint to the expenses of the facility based on the volume of use. Using
the ABC method it is possible to establish a causal link between the cost indicators and activities. This
method also contributes to more effective cost management in line with the business strategy of building
companies. The paper aims to demonstrate the applicability of the aforementioned methods in the
construction process and to indicate a higher level of objectivity in reporting particularly indirect -
general costs.

Кey words: ABC method, construction costs, indirect costs, allocation of costs, construction company

ALOKACIJA TROŠKOVA ABC METODOM U PROCESU GRAĐENJA

Rezime: ABC (engl. Activity-Based Costing) metoda obuhvatanja troškova zasniva se na metodologiji
merenja troškova i performansi aktivnosti, resursa i troškova objekta, pri tome se resursi pridruţuju
aktivnostima dok se aktivnosti pridruţiju troškovima objekta na osnovu volumena korišćenja. ABC
metodom je moguće utvrditi uzročnu vezu između troškovnih indikatora i aktivnosti. Takođe ova
metoda doprinosi efikasnijem upravljanju troškovima u skladu sa strategijom poslovanja građevinskog
preduzeća. Rad ima za cilj da prikaţe primenljivost pomenute metode u procesu građenja i da ukaţe na
viši nivo objektivnosti obuhvatanja naročito indirektnih - opštih troškova.

Ključne reči: ABC metoda, troškovi građenja , indirektni troškovi, alokacija troškova, građevinsko
preduzeće

Prof., PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy
erikam@uns.ac.rs

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. INTRODUCTION
One of the segments of construction management is cost management. Calculation
of costs should provide an objective accounting of the incurred costs, their transfer
into the price by calculation. The amount of costs has influence on the price which
also has an impact on the competitive position of the construction company.
Achieving positive financial results, or profit maximization requires cost
optimization.
Since the calculation of costs and especially cost optimization is a complex
management task, various methods have been developed. Therefore, there is not only
one way of cost calculation, because the costs are classified according to different
criteria, and thus apply different methods.
Major changes in the business environment of the second half and especially since
the end of the last century put business management system to face a new challenge
in the field of cost management.
Many factors especially technical and technological changes, many new business
transactions and various social factors caused the increase in the share of the general
operating expenses in total costs so it was necessary to find new methods of cost
accounting compared to the existing ones ie. The so-called traditional methods.
Based on research (Miller and Vollman, 1985), and (Johnson and Kaplan, 1991)
new information emerged regarding the calculation of costs. The Activity-based
costing can affect the calculation of costs to correct certain drawbacks of traditional
methods.
The paper starts from the thesis that the ABC method represents such a method of
encompassment of the costs which will provide more objective allocation of indirect -
general costs, activities, thus giving reliable information on the consumption of
resources and the selection of individual activity.

2. THE IMPORTANCE AND THE PLACE OF COST ACCOUNTING

Management of the business systems includes lifelong business decision-making
in order to achieve positive business result – profit. Profit can be increased by
increasing the revenues or reducing expenses. Most of the expenses are the costs of
the business itself, which means that business success is largely dependent on the
cost. The importance of cost accounting is primarily related to information for the
purposes of decision-making by management of the business system in order to create
a business strategy which would affect the positive effects of business on the one
hand and on the other to improve the competitive position. However cost
management has the purpose to achieve the optimum relationship between investment
and achieved results. This process is focusing on two main areas:
 Reduction of costs and
 Cost control

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Lowering or reduction of the cost tends to decrease the costs, wherein the
reduction should have positive effects.
Cost control is an effort to keep costs within planned levels, or so to manage the
processes to avoid exceeding the planned cost.
In modern intensive businesses, in the construction industry where the basic
process of construction takes place on the basis of well-composed project is difficult
to implement the reduction of costs, because the standards determine the level of
costs for specific objects. So lowering some of the costs can happen at the expense of
quality and thus do not achieve the positive effects. Cost control is showing better
effects because it focuses on cost management which keeps the costs within the limits
of budget and this may, to some extent, prevent the uncontrolled increase in
construction costs.

3. CLASSIFICATION OF COSTS AND METHODS OF CONTROL COSTS

To understand the role and importance of costs in the business and in the process
of building it is necessary to introduce cost types and classify them according to
various criteria. With the development of business and economy numerous costs
theories were created. One of the most popular classification is [3]:
 According to the natural type or appearance,
 By business functions,
 By segment (responsibility centers) and areas of cost,
 By way of assignment to carriers,
 By the change of the level of employment capacity (dynamic),
 By method of charging a particular period,
 By impact on the operating result,
 By the invest in the business process,
 By the contribution to the quality.
The following classification of costs is also very well known [1]:
 Natural types of costs,
 The economic and noneconomic costs,
 Direct and indirect costs,
 Cost per place and agents,
 Accrued, implemented and billed costs,
 Actual, planned and standard costs,
 Absorbed, preabsorbed and unabsorbed costs,
 Short-term and long-term costs,
 Costs that can be controlled and costs that are out of control,
 The production costs and transport costs,
 Fixed, variable and semi fixed costs,
 Other divisions and group costs.
Numerous other classifications include the already mentioned costs. Cost
classification has its foundation in an effort to identify as precise as possible the costs.

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On standpoint of the addressed topics we focus on analyzing the indirect costs of their
identification and coverage in the field of construction.
Classification of costs therefore aims to identify costs as accurately and
identification alone is the basis for the selection of appropriate methods of cost
management.
Modern business and the development of new management functions have
necessarily led to the finding of new management methods in the area of operating
costs. Often is cited paragraph in the literature that new methods should ensure
greater accuracy and efficiency in the allocation of certain types of costs compared to
traditional methods. Previously known methods of cost management are:
 The method of the traditional management of manufacturing costs (Traditional
Product Costing - TPC),
 The method of cost management based on processes (Process Based Costing -
PBC),
 The method of cost management on the basis of activities (Activity Based
Costing - ABC),
 Method for integration on the basis of cost management process / activity (PBC /
ABC),
 Method of target costs (Target Cost - TC),
 The method of budgeting based on activities (Activity Based Budgeting _ ABB),
 Method for balanced results found map (Balanced Score Card _ BSC),
 «Kaizen» Cost method (Kaizen Costing - KC),
 Value Analysis (Value Engineering _ VE),
 Methods of cost management quality (Quality Cost Management _ QCM).
For this paper we have selected the ABC method since it manages directly
indirect, general costs.

4. CHARACTERISTICS OF ABC METHOD

One of the most common activities of management is to find a way to successfully
manage costs and thus influence the competitive ability and profitability of the
company. This requires control of each organizational unit within the enterprises,
which are in the sense of organization an area of responsibility and control of costs.
Costing in individual organizational parts of the enterprise requires certain conditions,
in terms of quality and quantity, according to cost accounting, so it is necessary to
organize the accounting and adapt it to the needs of the new system of calculation.
The results obtained from the accounting are the real basis for the formulation of
better policies and for the achievement of a more favorable financial results of the
company.
By applying the ABC method, cost accounting shows better indicators that allows
estimation of effectiveness of each organizational part of the company, and thus a
more correct assessment of the contribution of individual organizational units to the

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financial results. The main purpose of these data is to be used by various users in the
process of decision making.
Practical application of simple forms of cost accounting has its origin in the US in
1940, when cost accounting system based on activities began to be developed. Then
in 1950 theorists were developing a similar system as a function of cost accounting.
Only in 1985 two authors Miller and Vollman published their work "The hidden
factory", in which it is pointed out that the cause of increasing general operating
expenses is to be linked with increased volume of various transactions. Only in 1987
Johnson and Kaplan in the book “Relevance Lost: The Rise and Fall of Management
Accounting” described the method of cost accounting, the basis for all further
research on this topic.
ABC method is based on the assumption that the cost holders use certain activities,
and activities or business processes use certain resources. Depending on the purpose,
the ABC method will offer solutions if there is adequate information basis. ABC
method analyzes the processes and spending and is allocating them to the holders.
Indirect costs and direct costs thus become associated with products and services that
are valued with respect to the justification of their sustainability, development or
abandonment. By applying the ABC method in the production company a better and
more objective classification of production is achieved compared to the traditional
method of classifying costs. The use of the ABC method allows the evaluation of the
product in accordance with its real contribution to the overall business results of the
company. [4]
ABC costing methods focuses on general and indirect costs of production that are
the reason for revising and redefining of the traditional methods of cost. The overall
costs of production are only indirect costs because, unlike the cost of direct materials,
direct labour cannot be directly covered by the cost holder and can have
characteristics of variable and fixed costs as well.
ABC method, as a modern cost accounting system aims to overcome the
weaknesses of traditional methods of cost in terms of cost and scheduling:
 Because of the increasing complexity of the production program of enterprises,
 Because of the increasing share of overhead costs within the total cost of the
product
 Because of increasing responsibility in terms of making important, strategic
decisions about product prices and costs, process technologies, etc., and in which
distortion of information on costs can lead and often lead to the realization of the
negative effects.
Implementation of the ABC method is based on the cost hierarchy, which includes
the following:
 Unit cost of output,
 Costs of product series,
 Support costs of products and
 Support costs of individual segments.

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According to the traditional method of indirect costs are divided into individual
groups and by certain keys (factor) are allocated to products or to a segment or
organizational. The traditional allocation of costs is shown in the following scheme
[7]:
Input
Final product
Resource input
Organization Organization Informations
Unit 1 Unit 1
Material
Energy Object of spending
2 2
Labour force
Financial means Production process Output
Informations

Scheme 1. Traditional allocation of the costs

ABC method focuses the allocation of the direct – common costs onto the
activities as shown on the scheme 2 [7]
Input
Final product

Resource input Use of resources Maintanance of final

users
Sales channels maint.
Material
Activities
Energy Informations
Labour force
Financial means Cost holders Object of spending
Informations
Output
Scheme 2 Cost allocation using the ABC method

There is a qualitative difference between the traditional conception of costs and

the concept of using the ABC method. ABC method joins the input resources over
activity to the holders thus enabling a clearer view of which activities consume as
much resources and within the framework of activities which elements are the direct
cost holders. This results in not having unnecessary activities that waste resources and
increase costs. ABC methods can actually contribute to savings in the use of
resources and thus in economizing with the costs.

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The process of implementing the ABC method therefore starts by identifying

activities which includes as accurate structuring of resource costs for each activity
and their transfer to cost as shown in Scheme 3. [7]

Resource Resource Resource

Input costs
costs 1 costs 2 costs n

Activities Activities Activities

Activity costs
1 2 n

Costs of the final

Cost holders: Final product – Services, Final users, etc.
product

Scheme 3. Analytical structure of the ABC method

Displayed logical structure of the ABC method clearly demonstrates the capability
of accurately separating direct from indirect costs, because the direct costs are
identified in input costs and indirect cost would be covered at the cost of activities. In
this way it is possible to obtain the more objective costing according to the holders or
the final product. Higher effects are achieved if it is possible to group the cost of
resources towards certain activities as shown in the following simplified scheme: [7]

Cost of the input – resources

Activities Activities Activities

1 2 n

Cost holders

Scheme 4. Process of allocation of the costs through activities onto holders

In the process of analysis and grouping costs may appear a number of variant
whereby certain activities may occur as activities which transpose indirect costs on
holders. In Scheme 4 as a simplified example, dashed arrows indicate indirect costs.
This means that when planning activities from 1 to n that provides a choice among a
great number of activities on order to rationalize the use of resources, as the cost of
activities already signaled the burden of indirect costs which should then be
transferred to the holder. Perhaps some activities that are more burdened by indirect
costs may be omitted (eg. more efficient organization that does not require large
overheads).

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Before making a decision to introduce the ABC method in business it is important

to establish a few key facts about a business entity of which will depend the project
implementation and operation of this method, namely:
 Economic activity of the subject,
 What is the main activity of the business entity and what are its aims,
 Size of the business entity,
 The number of employees,
 Organizational structure;
 Legal form.
By introduction of the ABC method cost performance and profitability can be
significantly improved, given that the existing traditional models in today's
production environment do not give a true picture of the actual cost of each product.

5. NEED FOR IMPLEMENTATION OF THE ABC METHOD IN THE

PROCESS OF CONSTRUCTION
Indirect costs cannot be directly separated to individual products and services at
their origin. These are mutual costs of the place, operation, phase, or jointly for the
whole company. They are the cost holders linked indirectly via selected key
allocations (eg. Production hours), so they are also called indirect costs.
Identification and coverage of costs according to certain criteria aims as already
mentioned above to classification of information to the cost calculation for the
purposes of comparison.
Indirect costs in the construction process can be grouped into:
1. Indirect costs for each construction site, which include:
 The cost of a preparatory finishing works,
 Uses a construction site and directing,
 Other costs of the construction site.
2. Indirect costs at the enterprise level are:
 Overheads of the administration,
 Cost of services (procurement, marketing, finance, legal service etc.),
 Other indirect costs at the enterprise level.
In practice, the construction companies apply additional calculation method
whereby indirect costs are added to the direct costs.
Price position of works is determined by analysis of price-calculation as follows:
[5]
Cp = EMAT+MEH + ERS x F (1)
where
Cp – price of position (works)
EMAT+MEH - Cost of material with cost of mechanization
ERS - Cost of work force
F - Calculative factor for the costs of work forces (gross earnings of production
workers)

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Calculative factor F is quotient of all associated costs not included in the

calculation of the prices and gross earnings of production workers:

F= PT /ERS , (2)
where :
F – calculatice factor,
PT - following costs (for example, cost of personnel, material costs, office supplies,
transport services, various fees and charges, representation expenses, etc.)
ERS - labor costs (gross wages of production workers)
The question can be asked with which objectivity calculative factor cover all
indirect costs of construction, or whether this factor exaggerates and jeopardizes the
competitive position of the construction company.
Implementation of the ABC methods in the construction process is dictated by the
cost of the structure. There are considerable differences in the prices of certain
objects. If the company specializes in high-cost facilities where indirect costs exceed
one-third of the cost structure, one can reflect on the need to introduce ABC method.
If in the cost structure the indirect costs make up a smaller part of it and do not
threaten effectiveness and profitability, the introduction of the ABC method could
give better effect, because it should be noted that the introduction of new methods
require new investments.
The introduction, therefore, of the ABC method is certainly not an easy task, but
the future development of the position of construction companies requires it among
other things, a change in the way business if companies want not only to survive in
the market but in a competitive environment ensuring growth and curves.

6. CONCLUSION
This paper presents the issue of cost accounting based on activities developed in
the 80-ies of the last century in an attempt to correct the shortcomings of traditional
cost accounting system. Implementation of ABC method is not simple, but in
practice there are examples of successful use. Theoretical considerations and
practical analysis include the possibility of its wide range of applications, including
applications in construction. Analyses have shown that the application of ABC
methods amenities contributes to more objective overview and allocation of indirect
costs and thus increasing the efficiency of construction companies.

REFERENCES
[1] Drury, C.,(2000), Management and Cost, London, Accounting Bussiness Press
[2] Ivković, B.Popović, Ţ.,(1994), Upravljanje projektima u građevinarstvu,
Beograd, IP „ Nauka“
[3] Majcen, Ţ.(1976), Troškovi u teoriji i praksi, Zagreb, Informator

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[4] Miller, A.,I., (1996), Implementing Activity Based Management in Daily

Operatios, New York, I.Wiley and Sons
[5] Ćirović, G.,Luković,O.,(2006), Finansijsko poslovanje i investicije u
građevinarstvu, Beograd, VGGŠ
[6] Stoiljković,N.,(2000), Activity Based Costing/Management – nuţnost a ne
odabir, Zagreb, Infotrend, br.84
[7] www.bi – control.hu

[425]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.055
1
Martin TUSCHER
Tomáš HANÁK2

MODELLING FLOOD LOSSES TO BUILDINGS: A RESEARCH

DESIGN
Abstract: The aim of this paper is to outline the research design of a doctoral research exploring various
aspects that may have a significant impact on the assessment of flood losses to buildings, such as depth
of flooding, room dimensions, materials, use of building etc. It reports present findings which have
already been published and outlines future research steps that will help to achieve a more accurate
evaluation of flood losses using loss curves or indicators.

Кey words: building, depth, flood, loss, room dimensions.

MODELOVANJE GUBITAKA USLED POPLAVA U OBJEKTIMA:

ISTRAŽIVANJE
Rezime: Cilj ovog rada je da prikaže istraživački projekat doktorske disertacije vezan za različite aspekte
koji mogu imati značajan uticaj na procenu gubitaka usled poplava u objektima, kao što su dubine
plavljenja, dimenzija sobe, materijali, namena objekta i slično. U radu se prikazuju predmetna
istraživanja koji su ve objavljena i konture budu ih istraživačkih koraka koji e pomo i da se postigne
tačnija procena gubitaka usled poplava koriste i krive gubitaka ili druge pokazatelje.

Ključne reči: objekat, dubina, poplava, gubici, dimenzije sobe.

1
Brno University of Technology, Faculty of Civil Engineering, Veveří 95, 602 00 Brno, Czech Republic,
tuscher.m@fce.vutbr.cz.
2
Brno University of Technology, Faculty of Civil Engineering, Veveří 95, 602 00 Brno, Czech Republic,
hanak.t@fce.vutbr.cz.

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1. INTRODUCTION
The primary reason for taking out a property insurance policy is to protect the
property from the consequences of contingencies. Such insurance provides financial
reimbursement in case the property is damaged due to the realisation of various risks.
Insuring residential buildings and unfinished other structures protects them not only
from theft and damage by a third person, but most importantly also from damage
caused by the forces of nature.
Real property insurance constitutes a significant part of the portfolio of insurers,
but it also burdens insurance companies with a large amount of paperwork. In the vast
majority of cases, every property owner, as a natural person, takes out a real and
personal property insurance policy [1]. In the case of large-scale natural disasters such
as floods, the insurance company may become unable to fulfil its obligations – timely
investigation and payment of insurance claims – due to an overwhelming amount of
incoming claims.
When an insured building is flooded, insurance companies are obliged to
investigate the claim as soon as possible, as it is necessary to document all the
damage caused to the real and personal property in time. This is a time- and money-
consuming process that should be completed as quickly as possible so that the insurer
can settle the claim and the insured has the finances necessary to repair the damage
and return the property to the state before the event. In the case of areal flooding, the
vast majority of insurance companies is unable to settle insurance claims in time. As a
result, payments of insurance claims are delayed and the actual extent of flood losses
is distorted, because the properties are cleared out and repaired before the damage can
be documented by insurance claim adjusters.
A simplified process of claim settlement would use a loss indicator per unit of
measure of the damaged building. With such indicator, the extent of flood losses
could be calculated more quickly, which would also lead to a quicker payment of the
claim by the insurance company. At the same time, using this indicator would
streamline the whole settlement process and lower the costs of work and
administration necessary for investigating the insurance claim on site.
This loss indicator would be included in every insurance policy concluded
between the insured and the insurance company. Specifically, the policy would
include a description of the insured building, description of materials used for
individual structures, technical parameters such as the length, width and height of
individual rooms and how old the building is. Based on these parameters, the loss
caused by flooding of the building would be calculated quickly and simply.
A similar research was conducted at the Faculty of Civil Engineering of the Brno
University of Technology [2]. This research modelled flood curves for different types
of buildings and areas based primarily on the depth of flooding and subsoil bearing
capacity.

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The loss indicator could be also used in determining losses for whole areas where
floods could potentially occur and damage real property. Based on simulations of
water depth, the number of buildings and the loss indicator, it would be possible to
determine the amount of expected flood losses for a given real property. This amount
would then be further analysed to determine whether it would be cost-effective to
build expensive flood control measures. Besides [2], a research conducted at the
University of Economics in Prague also examined a similar topic [3].
This paper aims to summarise the progress of a doctoral research of evaluation of
flood losses to structures using flood curves and coefficients and, most importantly, to
outline the future focus of the research.

2. RESEARCH METHODOLOGY AND RELATED ACHIEVED RESULTS

A loss indicator must be based on model situations that describe the type of
building, depth of flooding, floor area, side ratio and materials that are damaged or
destroyed by flood in the flooded building. Each of the elements listed above plays an
important role in modelling accurate loss curves. Therefore, all possible aspects of the
individual elements must be examined, including their interaction.
2.1. Building Categories
For a greater clarity of determining flood losses to real property, individual
structures were categorised according to their use: A – Houses; B – Apartments; C –
Common and cellar areas of apartment buildings. In the process of methodology
development, these categories were found to be insufficient and were further divided
into subcategories. Category A – Houses was divided into subcategories A1 – One-
floor houses without residential attic; A2 – One-floor houses with residential attic;
and A3 – Two-floor houses. The methodology is still under development and is
currently only being tested on category A – Houses, subcategory A1 – One-floor
houses without residential attic [4].
2.2. Unit Loss in Relation to Depth of Flooding
To determine the loss indicator, it was necessary to prepare model cases and
subject them to tests that would clearly show the loss per 1 m2 of floor area in relation
to the depth of flooding. Therefore, a database of 10 representative buildings in the
A1 subcategory was created. These were bungalows with floor area ranging from 60
to 140 m2. None of them included a garage or a cellar. In all ten cases, it was assumed
that they were built on flat ground and that their structural system consists of
insulated masonry structures.
A detailed bill of quantities was created in MS Excel for all ten houses. The rooms
were defined by their floor area, circumference, wall area and area of doors and
windows. All areas and circumferences in the individual buildings were summarised
in a table that included the quantities for laminate floorings, wooden baseboards,
ceramic floor tiles, indoor stucco, ceramic wall tiles, paint and facades. Afterwards,
the depth of flooding of each building was modelled. The depths of 0.4, 0.9, 1.4 and

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1.9 m were entered into the Excel programme one after another. As the depth of
flooding increased, so did the area of damaged plaster and wall paint. All calculations
of quantities were connected by formulas for quicker conversion of the quantities in
the summarisation table of the building [5].
2.3. Loss Indicator
Afterwards, the losses were evaluated in the KROS plus construction works
budgeting programme based on quantities calculated for the simulated depths. The
total calculated loss budgets for the model buildings were used to determine losses
using a weighted average per m2 of floor area for the depth of flooding of 0.4, 0.9, 1.4
and 1.9 m regardless of the overall floor area size. After entering the loss indicator
into the database, the budgeted losses and losses calculated by the conversion of floor
area and loss indicator were compared. The difference in the results was between -
16% and +15%.
During a review of the values, it was found out that the individual buildings were
all constructed in the same way, but they had a different layout of rooms. This
suggested that the comparison of the individual buildings must include not only the
floor areas, but also the vertical areas of the walls. A building with 100 m2 of floor
area and two rooms can be used as an example. If another building with the same
floor area of 100 m2 has 4 rooms and if both buildings are flooded at the same time to
the depth of 1 m, the building with the larger number of rooms will sustain greater
loss, as the ratio of vertical and horizontal surfaces will be greater than in buildings
with a smaller number of rooms [5].
2.4. Side Ratio
A model of a room defined by its floor and sides area was created to ascertain the
relationship between vertical and horizontal surfaces. The model room has 14
different floor areas from 4 to 30 m2 and each area is assigned a defining side ratio.
The side ratio [6] is expressed by the following equation:

Where:
l – length
w – width
with variables l and w representing room dimensions. Furthermore, the outcomes for
2 different SR values are compared; specifically, SR = 1.0 (square-shaped room), SR
= 0.1 (rectangle-shaped room). The core parameters of the examined sample are
listed in Table 1.

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Table 1. Parameters of the examined set [6]

Room size Area [m2] Side dimensions l, w Side dimensions l, w
group with side ratio with side ratio 0.1 [m]
1.0 [m]
l=w l w
RG1 4 2.000 0.632 6.325
RG2 6 2.449 0.775 7.746
RG3 8 2.828 0.894 8.944
RG4 10 3.162 1.000 10.000
RG5 12 3.464 1.095 10.954
RG6 14 3.742 1.183 11.832
RG7 16 4.000 1.265 12.649
RG8 18 4.243 1.342 13.416
RG9 20 4.472 1.414 14.142
RG10 22 4.690 1.483 14.832
RG11 24 4.899 1.549 15.492
RG12 26 5.099 1.612 16.125
RG13 28 5.292 1.673 16.733
RG14 30 5.477 1.732 17.321

For SR = 1.0 it holds that l = w; for SR = 0.1 it holds that l/w = 0.1. The following
structural and material specifications were set for the examined rooms: vertical
structures consist of masonry walls with plaster and paint, horizontal structures
consist of concrete panels and laminate composite flooring.
For the purposes of modelling damage to structures, the parameters of the flood
also had to be specified. At this stage of research, the depths of flooding used in the
models ranged between 0.0 m and 2.5 m. Other flood factors (duration of flooding,
flow velocity etc.) were not taken into account at this stage. Depth of flooding was
recorded for each 250 mm increase in depth; overall, the analysis assessed 154
scenarios for 11 different depths of flooding for a specific RS value. The scale of
damage to structures can be specified in this context. In the case of floors, the
structures in question are the tread layers and baseboards; in the case of walls, they
are plasters and paints. Damage to horizontal structures remains constant for various
depths of flooding, while damage to vertical structures increases in proportion to the
depth of flooding. This stage of research disregards damage to door wings and frames
as well as windows and windowsills to simplify the examined methodology. For the
purposes of loss modelling, depth of flooding of 0.0 m entailed only damage to

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horizontal structures, with no damage to vertical structures (disregarding any possible

damage to plaster by capillary action) [6].
2.5. Loss Curve
Afterwards, itemised budgets corresponding with the estimated level of damage
were developed for the individual scenarios to determine the costs of repair of the
damaged structures. For the flooding of masonry walls (vertical areas), the budget
includes costs of works related to the removal of plaster, high-pressure cleaning and
disinfection of the masonry, manual plastering using lime stucco plaster and final
surface treatment using two layers of antimicrobial paint. Flooding of floors
(horizontal areas) was modelled specifically for laminate composite flooring. In this
case, the budget covers works needed to mount and remove laminate floating
flooring, baseboards and bottom counterbalance layers, just as in [6]. Calculation of
costs related to transport of rubble and material on the construction site was added to
the work done on both vertical and horizontal structures. Afterwards, unit loss for 1
m2 of room floor area was calculated from the resulting amount of total loss.
The prices of work and materials was calculated using the KROS plus budgeting
programme with 17.00 price database [8]. The materials used are priced at the
standard level. All prices for work and material are listed without VAT (exchange
rate CZK 1 = EUR 0.0369 as of 19 October 2015). Creating a database with 154
different situations for defined RS = 1.0 and RS = 0.1 brought a large dataset of 308
model situations; loss per 1 m2 of floor area was calculated for each situation. In the
next step, loss curves for the individual room size groups were created for the given
RS.
Altogether, there are 14 lines with each line representing one rooms size group
(RG) [7]. It has been observed that loss per 1 m2 of floor area increases linearly with
the increasing depth of flooding of the room. In general, it holds that the larger the
area of the room, the lower the unit loss and vice versa. This dependence arises out of
the changing proportion of the amount of loss resulting from damage to horizontal
and vertical structures in the total loss. The closer RS is to 1.0, the lower the unit loss
and vice versa – the larger the difference between the length and the width of the
room, the higher the value of the unit loss. This dependence is valid regardless of the
size of the room. The reason is a longer room circumference related to the lower side
ratio value; the primary consequence of this is an increase in the areal extent of
damage to vertical structures (plaster, paint). These connections were already proved
during the previous stage of research and are confirmed at this stage [7].
It is interesting to note that an increase in the depth of flooding corresponds with a
more profound difference between unit losses, for example when comparing different
RG or RS. Figure 1 shows that the significance of the relative difference of unit loss
per m2 for different RS (1.0 m and 0.1 m) within one room size group increases with
increasing depth of flooding. Specifically, the amount of unit loss for RG1 and depth
of flooding of 0.0 m is 14% higher for RS = 0.1 than for RS = 1.0. At the same time,
the amount of unit loss for the depth of flooding of 2.5 m is 59% higher for RS = 0.1

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than for RS = 1.0. This dependence can also be seen in the case of values related to
RG14 as well as for situations when RS is constant and RG is changing [7].

Figure 1. Comparison of loss curves for RG1 and RG14 with RS = 1.0 and RS = 0.1

It can therefore be concluded that the impact of room dimensions on the amount of
unit loss increases in significance with increasing depth of flooding. This is caused by
the changing ratio of damage to vertical and horizontal structures.

3. FUTURE RESEARCH
So far, the research confirmed that there is a relationship between the depth of
flooding and the amount of unit loss determined with regard to the impact of room
dimensions. The results proved that with increasing depth of flooding, the impact of
room dimensions on the ability to evaluate the loss with required accuracy becomes
more significant. In other words, the higher the depth of flooding, the greater the
inaccuracy in determining the unit loss, unless room dimensions are taken into
account during the evaluation process.
To simplify the calculation models, only the floor and vertical structures of the
model rooms were taken into account; doors and windows were not included in the
model. Furthermore, the relationships described in this paper are valid for individual
(separate) rooms, not for whole buildings. Therefore, future research should be

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directed not only to accounting for doors and windows, but also to modelling various
material specifications so as to asses the significance of the examined factors on the
level of the whole building.

Figure 2. Methodology development process

Figure 2 shows the process of methodology development and predicts the steps
needed for a successful outcome.
More detailed future research into the use of loss curves and indicators could
contribute to a more accurate choice of parameters for loss assessment, which is used
not only for settling insurance claims but could also be helpful for the prediction of
potential future losses and adjustment of loss rates.

4. CONCLUSION
During the research, it was necessary to adjust the intended steps based on the
results to achieve an accurate loss indicator. Every inaccurate result moved the
research a step ahead thanks to adding and specifying other specific characteristics
that are an essential part of the calculation. The original model database of buildings

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assumed that loss per m2 of floor area will be the same if the depth of flooding is the
same. This assumption was refuted and the research gradually focused on individual
rooms inside the buildings rather than the buildings as a whole. The loss indicator is
modelled at this level and after further refining it will be applied to whole buildings.
Afterwards, its accuracy will be tested in practice on actual investigated insurance
claims; if it stands the test, it could be then used in academic and commercial
practice.

ACKNOWLEDGMENT
The project presented in this paper is supported by research grant FAST-J-15-2706
entitled “Refining the Calculation Methodology Used to Determine Damage to
Buildings Caused by Floods”.

REFERENCES
[1] Hanák, T., 2007. Modelování optimální struktury zdrojů finančního krytí škod na
pojišťovaných stavbách: disertační práce. Brno: VUT Brno, 131 s.
[2] Korytárová, J. a kolektiv 2007. Povodně a nemovitý majetek v území. Brno:
Akademické nakladatelství CERM s.r.o., ISBN 978-80-7204-573-0, 181 s.
[3] Čamrová, L. a kolektiv 2006. Povodňové škody a nástroje k jejich snížení. Praha:
IEEP Fakulta národohospodářská. ISBN 80-86684-35-0, 422 s.
[4] Tuscher, M.; Hanák, T., 2014. Problematika oceňování povodňových škod z
pohledu pojišťovny s využitím škodního ukazatele. Brno: VUT Brno, Juniorstav
2014. s. 1-5. ISBN 978-80-214-4851-3.
[5] Tuscher, M.; Hanák, T., 2014. Assessing flood losses from the perspective of
insurance companies using loss indicator. Brno: VUT Brno, PBE PhD FORUM
2014, ISBN 978-80-214-5050-9.
[6] Tuscher, M.; Hanák, T., 2015. Evaluation of Flood Losses to Buildings: Effect of
Room Dimensions. Periodica Polytechnica Social and Management Sciences,
Online published: 02-06-2015, pp 1-5, DOI: 10.3311/PPso.8158.
[7] Tuscher, M.; Hanák, T., 2015. Modelling Flood Losses to Buildings:
Relationship between Room Dimensions and Depth of Flooding. Accepted for
publication in proceedings of 2nd International Conference "Innovative
Materials, Structures and Technologies, Riga, Latvia, 30.09. - 02.10.2015.
[8] Kalkulační a rozpočtovací program KROS plus 2014, Praha ÚRS a.s.

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ARCHITECTURAL AND URBAN
PLANNING AND DESIGN
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Borislav Yankov BORISOV

SPATIAL CONCEPT FOR THE INTEGRATION OF TOURISM AND

IMMOVABLE CULTURAL HERITAGE IN THE GENERAL
DEVELOPMENT PLANS IN MUNICIPALITY
Abstract: The development of tourism is closely related to city planning. The general development plans
are one of the main instruments for the implementation of this commitment, in which an important role
has the immovable cultural heritage. Spatial Planning Act provides sustainable and integrated
consideration of this issue, but does not specify the methodology by which it will be implemented. The
theoretical exploration of methodological guidelines and principles in the development of a spatial
concept for the integration of tourism and immovable cultural heritage in the general development plans
in Bulgarian aims to justify the possibilities for more systematic, effective and efficient handling of this
issue.
Кey words: spatial concept, tourism, cultural heritage, urban development master plan (MP)

PROSTORNI KONCEPT ZA INTEGRACIJU TURIZMA I

NEPOKRETNOG KULTURNOG NASLEĐA U OPŠTE RAZVOJNE
PLANOVE U OPŠTINAMA
Rezime: Razvoj turizma je usko povezan sa urbanističkim planiranjem. Opšti razvojni planovi, u kojima
nepokretno kulturno nasleđe igra značajnu ulogu, predstavljaju jedan od glavnih instrumenata za
sprovođenje ove obaveze. Zakon o prostornom planiranju pruža održivo i integrisano sagledavanje ovog
pitanja, ali ne precizira metodologiju po kojoj e ono biti implementirano. eorijsko istraživanje
metodoloških uputstava i principa u razvoju prostornog koncepta za integraciju turizma i nepokretne
kulturne baštine u opštim razvojnim planovima u Bugarskoj, ima za cilj da opravda mogu nosti za više
sistematično, efektivno i efikasno rukovanje ovim pitanjem.
Ključne reči: prostorni koncept, turizam, kulturno nasleđe, urbanističko planiranje master plan (MP)

Dean of the Faculty of Architecture of VSU "Lyuben Karavelov" – Sofia, Head of the Department "Urban
Planning, Theory and History of Architecture", 1373Sofia, str. Suhodolska 175, Bulgaria, e-mail: archbb@abv.bg

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1. INTRODUCTION
The main goal of the spatial concept for tourism and conservation, use and
development of the immovable cultural heritage in the general development plans
/GDP/, hereinafter referred to spatial concept (SC) or the concept is to create
conditions for sustainable development of tourism for the protection and socialisation
of the cultural heritage in the territorial and urban dimension. The concept contains
proposals and strategic guidelines for the development of tourism through
implementation of the immovable cultural heritage (ICH) as a specific resource for:
socio-economic and urban development; the development of urban functional systems
(work, housing, green system, tourism and recreation, social infrastructure, transport
and communication system, engineering infrastructure, etc.).
This research starts from the premise that as a tourist activity in the Tourism Act
are defined "real cultural values under the Cultural Heritage Act, cultural institutes
under the Protection and Development of Culture Act, the protected areas under the
Protected Areas Act in case that they are socialized and offer conditions for
acceptance and maintenance of tourist visits, and in accordance with the arrangements
for their protection and with the internal rules of the persons granted the right of
management ...." [1].
2. EXPOSITION
2.1. Clarifying the role and place of the spatial concept for tourism on the
protection and use of immovable cultural heritage in the framework of the
urban development master plans
Тhe spatial concept for every master plan has specific characteristics that are
different for each town and each municipality, but it methodologically complies with
the country urban development plans and normative documents. Such a document is
"Strategy for the Sustainable Development of Tourism in the Republic of Bulgaria
Horizon 2030" (project). In the chapter "Cultural Tourism" it is clarified that
"Bulgaria is one of the oldest European countries and is the only one which has not
changed its name since it was founded; The successor of the ancient civilizations –
Thracians, Romans, Byzantines and Bulgars who left in these lands extremely
valuable artistic and architectural testimonies of their developed cultures; Attractive
destination for people with an interest in history and culture; The resources for the
development of cultural tourism in Bulgarian include archaeological, architectural,
ethnological, religious sites, historical landmarks and cultural institutions – museums,
galleries, community centers and cultural events of various kinds, involving over
intangible culture, as well as "creative" tourism, in which tourists create culture. They
are characterized by their diversity, authenticity and uniqueness..."[7].
2.2. Priorities of the tourism in the spatial concept
An essential part of the purpose of the concept is connected to the budget
allocation, the allocation of time for recreation and tourism in view of the various

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forms of systematic and excursive, periodic and episodic tourism. The

implementation of the envisaged in the concept tasks should lead to improving the
market positions of local tourism and will depend on the possibilities for the
realization of the following priorities:
 Maintaining and improving the quality of the natural and anthropogenic tourist
resources in organizational aspect;
 Developing a sustainable cultural tourism taking into account the advantages of
the diversity, uniqueness and authenticity of the tourist resources of the ICH;
 Maintaining the balance between the development of cultural tourism and the
conservation of resources;
 Improving the infrastructure – social and technical;
 Applying good practices and innovations in products, technology and human
resources for the development of tourism;
 Developing a strategy for urban cultural tourism that shall be integrated into the
MP;
 Cultural tourism has to be seen as part of the urban and regional planning, so to
be connected with other plans and programmes for development (rural
development, infrastructure development, education, health, etc.).
 Detection and recovery of architectural-urban potential, regardless of its cultural
and historical value;
 Inclusion in the framework of the common tourist products with other countries,
regions, communities and sectors;
 Promotion of the city or the municipality which is developed as a tourist
destination in the master plan;
 Formation of new travel products to realize the potential of the new sites,
ensembles and other objects;
 Balanced /as continuity and change/ urban development; Optimizing the design
intervention.
 Creating prerequisites for the formation of a common marketing local politics in
tourism joint and third markets;
2.3. The importance and application of the concept, indirectly evaluated in
theoretical studies of other authors
Many authors of professional analyses, studies and thematic studies related to
tourism develop various aspects of the problem of planning of tourism within the
framework of the MP and indirectly assess the scientific and practical significance of
this aspect. Assoc. Prof. Dr. M. Mihailov is one of those professionals, who in his
theoretical work "Strategic approaches for the development of cultural tourism" in p.
11-12 says: "Methodology and the overall process of protection of cultural values
depend on their type, status and location. Territorial spatial protection of immovable
cultural heritage covers the design, coordination and approval of spatial plans, as well
as financing and carrying out activities for their protection and exposure. It includes:
 protection regimes;

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 schemes of protected areas for the conservation of immovable cultural

heritage;
 master plans of protected areas for the conservation of immovable cultural
heritage and specific rules and regulations to them;
 plans for the conservation and management of immovable cultural values"[2].
According to Mihailov "preservation of cultural values is accomplished through
specialized activities, conservation, restoration and adaptation, which aim is to
prevent the demolition, their condition stabilization, as well as facilitating their
perception and evaluation for maximum preservation of authenticity..."[2]. These
activities are planned and are the subject of spatial plans developed to them, including
the concepts of tourism and the ICH.

3. THE METHODOLOGICAL APPROACH, TOOLS AND

TECHNOLOGICAL PECULIARITIES IN THE DEVELOPMENT OF
THE SPATIAL CONCEPT
3.1. Consideration of the Spatial Concept as a kind of scheme.
In the framework of schemes supporting the MP on the Spatial Planning Act
(SPA), the scheme of the concept illustrates the extent of the urban planning
intervention in the framework of the existing territorial structure, recommended
specific rules and norms, illustrates the location of immovable cultural values and
cultural itineraries, sets the tourism objects and the ICH. Comply with the
requirements of Regulation No 8 for the volume and content of spatial plans [6].
Exploration of the possibilities of SC as specialized research and analysis
accompanying the textual part of the MP on the SPA;
Exploration of the possibilities of SC as a prognostic modeling of urban
development in the framework of the integrated planning on the Spatial Planning Act
and Regional Development Act on hypotheses for tourism and conservation, use and
development of the immovable cultural heritage in the urban development master
plans. Elaboration of alternative options, their comparison and evaluation.
3.2. Determination of the territorial scope of the spatial concept for tourism on
the protection and use of immovable cultural heritage includes:
Research and design in scope beyond the master plan, at national, regional and
district level; Macro level of territorial research is strongly important for the creation
of an integrated in appearance and content concept, in which the mutual commitment
of the contact areas is essential.
Research and design on the scope and framework of the master plan; Creating the
concept for the entire territory of the plan.
Detailed studies, research, analyses and developing fragments of a part of the
territory of the MP. "The micro level" on territorial survey is also a sine qua non for a
comprehensive explanation of both analytical and prognostic parts of the concept.

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3.3. The specific tools and means of the spatial concept for tourism development
in the protection of the immovable cultural heritage.
The individual specialized tools of the concept contains the development,
discussion and planning of specific arrangements for protected areas and for the
protection of the immovable cultural heritage as a tourist resource. Through the
methods of renovation, reconstruction and conservation the immovable cultural
heritage objects within the SC can fit better as part of the urban environment;
The concept involves the development, discussion and planning of specialized
circuits at different scales and details on tourism development, ensuring the
preservation of the sites of the immovable cultural heritage and complementary
modern achievements, current uses and their socialization;
Immovable cultural heritage conservation within the SC is seen as part of the
overall specialized policies for the sustainable development of the environment
realized by the means of the MP.
3.4. Spatial study and territorial modeling of the historical development of the
urban structure. Comparative analysis of stages and specific haracteristics
in urban development
In the development of tourism and the ICH schemes to MP the development of
urban structure can be traced historically and compositionally backup cadastral and
regulation plans. Comparative diagrams (Figures 1 and 2) show important aspects of
continuity and variability, regardless of the sequence of zoning changes that led to the
image of a modern town in the form in which it is at the moment.

Figure 1- Graphical study of part of the Master Figure 2-Comparative scheme of the urban
Plan of Samokov, from 1895, with more structure from 1895 and updated cadastral
important objects (Prof. Dr. arch. B. Borisov) map (Prof. Dr. arch. B. Borisov)

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3.5. The determination of the extent of the intervention, depending on the

criteria for the conservation of urban memory and image.
The dosage of the planned intervention is one of the most delicate terms of the
high professional approach in the development of the spatial concept for tourism and
the ICH within the MP. In this aspect could define various characteristics and degrees
of intervention could be defined, namely:
 conservation – the restrictive regime;
 reconstruction-renovation;
 new construction in terms of the specific urban context, while maintaining the
context of the existing environment;
 removing, reshaping or partial reconstruction (including façade redecoration or
redesigning of the ground level) of objects that prevent compliance with the
criteria for the protection of the ICH and are not compatible with the criteria
for the development of tourism.
3.6. Research of historic and cultural resource in several key for tourism aspects
within the SC:
 as criteria for sustainable tourism, spatial and socio-economic development;
 as a specific sector-professional tourism factor in spatial planning;
 as a promoter of tourism through the development of leisure activities, the
rationalization of leisure, public liveliness, servicing etc.
3.7. The elaboration of proposals for the protection of immovable cultural
heritage (ideas, status, territorial specificities, conceptual approaches) as a
tourist resource.
In the MP by the methods of the SC are defined:
 Territories with the status of the immovable cultural heritage, conservation of
values types: reserve, security zones, status of single and group real cultural
values, cultural places and landscapes – compulsory regulatory regimes are
developed;
 Territories without status, but with the potential for the conservation of
immovable cultural heritage - recommended regulatory regimes are developed;
 Cultural-informative and thematic itineraries. Macrostructural itineraries,
itineraries in the scope of the MP, urban interior itineraries, etc.;
 Specific rules and regulations for the application of the MP with the aim of
conservation of immovable cultural heritage. Types, rules and norms:

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4. RESEARCH, STUDIES, EXAMPLES AND RESULTS IN THE

DEVELOPMENT OF THE CONCEPT OF TOURISM AND THE ICH.
4.1. Experimental results and empirical research in the framework of specific
developments to the Master plan of the town of Samokov from the collective
headed by Prof. Dr. arch. B. Borisov[3].
In the Master plan of the town of Samokov and the metropolitan territory,
developed by the collective of the National Center for Regional Development
(NCRD) headed by Prof. Dr. arch. Borislav Borisov, special attention is paid to the
development of cultural tourism as an opportunity for conservation, socializing and
further disclosure of the potential of the immovable cultural heritage of Samokov and
the metropolitan territory.

Figure 3-Countryside cultural thematic tourist Figure 4- Part of the immovable cultural heritage at
itinerarie, Prof. Dr. arch. B. Borisov the MP of the town of Samokov with great potential
for the development of tourism

4.2. Examples and results of theoretical study on spatial concept of the

immovable cultural heritage and tourism at the Master plan of the town of
Stara Zagora, made by a collective, headed by Prof. Dr. arch. B. Borisov. [4]
Bulgarian territory was included in the East Trans Balkan road which is a part of
the network of cultural corridors of South-East Europe and contains in itself the
territory, seen from the MP of Stara Zagora.

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Figure 5- Scheme of the MP, which shows the Figure 6-A conception of immovable cultural
connection between the traditional town and the heritage at MP of the town of Stara Zagora,
other possible cultural and thematic itineraries collective headed by Prof. Dr. arch. B. Borisov

4.3. Cultural-informative itineraries in the spatial concept of tourism and the

ICH at the MP of the municipality of Blagoevgrad, made by a collective
headed by Prof. Dr. arch. B. Borisov. [5]
Cultural-informative itineraries are based on the rich heritage of the settlements of the
municipality and are a prerequisite for the development of cultural-informative
tourism. The MP offers mainly four cultural-informative itineraries within the
boundaries of the municipality: Urban and suburban itinerary includes the town of
Blagoevgradp; Eastern Mountain itinerary – along the Bistritsa river; Western
Mountain itinerary, South-west Mountain itinerary.

Figure 7- Immoveable cultural A scheme of immovable cultural heritage at the MP of the municipality
of Blagoevgrad, made by a collective headed by Prof. Dr. arch. B. Borisov.

5. FINDINGS AND CONCLUSIONS ON THE PRACTICAL APPLICATION

OF THE SPATIAL CONCEPT FOR TOURISM AND THE IMMOVABLE
CULTURAL HERITAGE WITHIN MASTER SPATIAL PLANS
By the improvement of the methodology for the development of a spatial concept for
tourism through the protection and use of immovable cultural heritage in the

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framework of the master spatial plans of cities and towns in Bulgaria you can create,
on the one hand, better conditions for conservation, and protection of such cultural
heritage and to improve citizens' access to cultural values, and on the other hand to
stimulate the development of tourism by means of cultural and historical heritage in
the master spatial plans and their implementation. The specifics of this design and
planning toolkit requires in-depth studies on all the features typical of a particular
town or municipality, which made the MP. The methodology of the spatial concept
for tourism and the immovable cultural heritage within the master spatial plans
provides a reliable systematic approach that is experienced in the examples of this
theoretical study. Expected scientific and applied result can be achieved with long-
term effects on the development of tourism in the city planning of Bulgaria.

6. REFERENCES
[1] Article 3(2), point 21 of the Tourism Act
[2] Mihailov, Mihail (2012) Strategic approaches for the development of cultural
tourism. Working Paper. p. 11-12
[3] Master plan of the town of Samokov and the metropolitan territory, developed by
the collective of the National Center for Regional Development (NCRD) headed
by Prof. Dr. arch. Borislav Borisov (http://www.ncrdhp.bg)
[4] Master plan of the town of Stara Zagora, developed by the collective of the
National Center for Regional Development (NCRD) headed by Prof. Dr. arch.
Borislav Borisov (http://www.starazagora.bg/worktemp/OUP_2011.pdf)
[5] Master plan of the municipality of Blagoevgrad, developed by the collective of
the National Center for Regional Development (NCRD) headed by Prof. Dr.
arch. Borislav Borisov (http://www.blgmun.com/cat68/OUP/)
[6] Regulation No8 (for the volume and content of spatial plans), prom. SG.
No.57/14 June 2001, amend. SG. No.22/Feb 2014
[7] Strategy for the Sustainable Development of Tourism in the Republic of Bulgaria
Horizon 2030", p. 62

[444]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Borislav Yankov BORISOV

TOURISM AS CRITERION FOR DEFINING THE REGION IN THE

TERRITORIAL DEVELOPMENT ZONING OF BULGARIA
Abstract: The idea of writing this article is deeply enshrined in the hypothesis developed by me for a
new spatial-development zoning of the territory of Bulgaria and the necessity of unifying and integrating
the regional and territorial (spatial) planning through unified spatial planning documents. The
hypothesis, herein, is illustrated or affirmed within the aspect of analytical study of the Black Sea region,
as well as within the context of its tourism development and comparative analysis of the territorial and
tourism zoning.

Кey words: Territorial development, region, tourism and territorial zoning

TURIZAM KAO KRITERIJUM ZA DEFINISANJE REGIONA U

KONTEKSTU ZONIRANJA PROSTORNOG RAZVOJA BUGARSKE
Rezime: Ideja pisanja ovog rada je duboko utemeljena u sopstvenu hipotezu za zoniranje novog
prostornog razvoja teritorije Bugarske i potrebu objedinjavanja i integrisanja regionalnog i teritorijalnog
(prostornog) planiranja kroz objedinjenu prostorno-planersku dokumentaciju. Hipoteza je u radu
ilustrovana ili potvrđena u pogledu analitičke studije o crnomorskom regionu, kao i u kontekstu
njegovog turističkog razvoja i komparativne analize teritorijalnog i turističkog zoniranja.

Ključne reči: Prostorni razvoj, regija, turizam i prostorno zoniranje

Dean of the Faculty of Architecture of VSU "Lyuben Karavelov" – Sofia, Head of the Department "Urban
Planning, Theory and History of Architecture", 1373Sofia, str. Suhodolska 175, Bulgaria, e-mail: archbb@abv.bg

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1. INTEGRATION OF THE TERRITORIAL DEVELOPMENT AND

REGIONAL PLANNING /INCLUDING TOURISM/ IN UNIFIED
DOCUMENTS.
The theoretical concept of the integration of the territorial development cum the
urban and regional planning in a single document theoretically, as well as practically,
may lead to a better efficiency of the planning as a whole and to economizing
valuable and socially beneficial resources, time and personnel. A scientifically proven
reduction from six to three types of planning documents can be achieved, while as a
number of legally regulated - a total of 16 to 6 urban planning documents, which
would have a substantial practical application. The regulation of the Black Sea
region, as part of this theoretical concept through its experimental modeling and
empirical research, provides enough conclusions for scientifically applicable
generalization in this material. For the purpose of exemplifying some of the pre-
planned changes to the territorial planning and regional development (LTPRD - the
"Stroitel" newspaper, iss. 15/11.04.2014) [1] the graphic illustration of the attached
diagram (Figure 1) can be used.

Figure 1- Territorial development – main changes of reduction and integration of LTPRD

(Law on Territorial Planning and Regional Development) ( Prof. Dr. Arch. B. Borisov, the
"Stroitel" newspaper, issue 13/28.03.2014, p. 10) [2]

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2. NEW TERRITORIAL DEVELOPMENT ZONING

A reduction of the planning regions, following NUTS 2 1, from six to four has
been proposed, thus achieving a more even distribution of the population by regions,
better matching under EUROSTAT 2, a better and more rational management, and
their more appropriate formation by functional territorial development feature. Such
may be the Danube region, the Black Sea region, the Thracian region and the
Southwest region. The new territorial development country zoning offers a theoretical
concept wherein the entire territory is separated or defined into four regions, namely:
1) The Danube region (Misia) covers 12 areas, namely the areas with town centres
Vidin, Vratsa, Lovech, Montana, Pleven, Veliko Tarnovo, Gabrovo, Razgrad, Rousse,
Silistra, Targovishte and Shumen, inland waterways and the Danube ports of the
Republic of Bulgaria;
2) The Black Sea region encompasses the territories of the three areas, namely
those with town centres Dobrich, Varna and Bourgas, the marine spaces and the sea
ports of the Republic of Bulgaria; /a possible option is the inclusion of Shumen
region/;
3) The Thracian region (Thrakiya) covers the territories of eight areas, namely the
areas with town centres Kardzhali, Pazardzhik, Plovdiv, Smolyan, Haskovo, Sliven,
Stara Zagora and Yambol.
4) The South-west region comprises the territories of five areas, namely the areas
with town centres Blagoevgrad, Kyustendil, Pernik, the district of Sofia and Sofia
city;
This proposal is based on the territorial development /including the tourism/
features of the different regions, which gives grounds for uniting territories with
identical, similar or complementary characteristics, not only in socio-economic but
also in technical and spatial aspects.

Figure 2 - Concept for new zoning of Bulgaria (Prof. Dr. Arch. B. Borisov)

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The system of the new level-2 four regions is a territorial development structure
with greater potential integration, concerning the territorial policy of the European
Union, as it shall serve for more effective implementation of the European inter-
regional connections. It meets more accurately the sense of regional belonging and
identity to a certain territory. The system of cultural corridors in Southeastern Europe,
including the passing of five corridors through the regions - the Danube corridor, the
Diagonal corridor (Via Diagonalis / Via Militaris), the Black Sea corridor Via
Pontica, the Western Trans-Balkan corridor, the Eastern Trans-Balkan corridor, also
more accurately fits into the concept of a new spatial planning or zoning.

3. TOURISM ZONING IN TERMS OF COMPARISON TO THE

TERRITORIAL DEVELOPMENT ONE
Tourism zoning has adopted and has been using tourism resources as criteria and
thus its aim is the management of the tourism sector according to specific territorial
characteristics. In this sense, it is consistent with the criteria for territorial
development zoning in general. Following the implemention of the specialized
Tourism Act in 2014, an alternative proposal for tourism zoning was developed by
the National Centre for Territorial Development /NCTD/ at the Ministry of Regional
Development[3]. This new concept for tourism zoning of Bulgaria, observing the
sector specificities characteristic of the development of this industry, has been drafted
upon assignment by the Ministry of Economy and Energy. The Tourism Act of 2013
provides for the establishment of organizations for management of tourist areas and
the separation of the country into such, but does not offer a comprehensive scheme of
zoning. A scheme for tourism zoning has been proposed based on analysis of existing
proposals and studies carried out, which has undergone theoretical and
methodological research, whose practical purpose has been to address the real
marketing targets and the formation of organizations for management of tourist areas.
The same was published in the "Construction and City" newspaper (issue 27/7-13
July, 2014)[6]. It has been proposed that tourist areas shall be designed (formed up)
and their functions be determined on the basis of sector criteria, not on integrated
territorial development criteria. Under the provisions of the Tourism Act, the future
areas should be seen as marketing tourist management areas, as related to the type of
activities held in three main directions based on region identification. We can also
contend that as far as zoning is concerned they are spatial development in nature:
 Creating regional tourism products
 Realization of regional marketing and advertisement;
 Tourism coordination and management at a regional level.
Here, it may be noted that the existing zoning by regions in the current RDA is
contrary to the current tourism zoning and the criteria for its establishment as
proposed by NCTD. The need of tourism zoning of Bulgaria is motivated by the
desire to develop competitive tourism, conduct regional tourism policy, based upon
the spatial characteristics and specificity of the various parts of the country,

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implement effective regional marketing, which shall make tourist areas /regions/
recognizable for the potential tourists and to successfully promote them on the
domestic and international tourist market, but all those are, per se, aspects of the
territorial cum regional planning and zoning. The tourist zoning scheme proposed by
NCTD seeks to take into account the naturally shaped tourist territorial formations in
our country over the recent years - regional tourist associations and groups of
municipalities united for the implementation of projects for developing regional
tourism products and destination marketing under OP Regional Development 2007 -
2013[5], but is not based on the demand for a universal spatial zoning and division of
sustainable regions. The tourism zoning scheme proposed by NCTD covers the entire
territory of the country in which municipalities are the smallest territorial unit for the
demarcation of the areas but cannot find justification in the existing or in a new
regional zoning as a statutory or institutional regulation. Nine (9) are the tourist
regions that have been defined, which according to the creators of the project are "big
enough" to be clearly identifiable on the tourist map and "small enough" to be
managed effectively, but they are not recognized or supported by clear regional
differentiation and institutional form of governing. In shaping the tourist areas, NCTD
points out that it has been guided by the following principles and requirements, which
practically do not cover the criteria for land or territorial zoning and are not based on
a workable regional concept /the "Stroitelstvo i Gradat weekly" newspaper (iss. 27/7-
13 July, 2014) [6].
 “The area boundaries shall match the actual dimensions of tourism
development (including the existing organizational structures) or the findings
on tourism potential;
 Attractiveness - significant attractions to be available (exposed or potential
ones), which shall provide rich enough "menu" of the tourist offers, that may
make it possible to create a complex tourist product (a product mix), and can
keep visitors for at least a few days of stay;
 Infrastructure provision – the areas may offer or have the potential to develop
a complex of tourist services and relevant infrastructure for the needs of
tourists and tourism business;
 Homogeneity - relative similarities of the natural and socio-economic
conditions, resource potential, product structure, and regional identity (to be
perceived as complete units of major market segments, local authorities,
tourism business and travel associations and agencies);
 Territorial integrity (compactness) - territorial fragmentation of the region and
/ or overlapping with other areas are not allowed (one municipality may
belong only to one area);
 Tolerance - wherever possible to aim at preserving the territorial integrity of
the existing regional associations and other voluntary formations between
municipalities, provided this is not in conflict with the above criteria."

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Four of the six requirements possess territorial development characteristics,

which confirms the relevance of the new proposal for a regional segmentation under
the project – LTPRD.
The formation of a new united Black Sea region is assessed positively by local
authority representatives from large municipalities, as indicated in the publication
"Varna, Bourgas and Dobrich to be brought together in one region, mayors require”.
(DarikNews.bg, March 25, 2009)[4].

Figure 3 - Scheme of the proposal for the Black Sea region (dariknews.bg) [4]

„A new zoning is to be developed, within which the regions of Bourgas,Varna and

Dobrich municipalities shall be brought together in a unified or common Black Sea
region.” This proposal from the Mayor of Bourgas, Dimitar Nikolov, and the mayor
of Nessebar, has been announced today at the 15th annual general meeting of the
Association of Black Sea Municipalities (ABLM) by Atanas Stoilov, Chairman of the
Board of the association. According to Dimitar Nikolov it is perfectly feasible, but it
requires some legislative changes. "Burgas connects more easily with Varna and
Dobrich than with Stara Zagora, and our problems are the same,"[4] said
Nikolov.”The idea is worth realizing, but it cannot happen soon” [4], said Zdravko
Sechkov from the Foundation for local governance. The text cited once again
confirms the relevance of the proposal for a new territorial zoning and spatial
development of the Black Sea region.

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4. INTEGRATION OF TOURISM AND TERRITORIAL DEVELOPMENT

ZONING IN FOUR GENERAL AREAS.
In the draft of NCTD [3], some new geographical names of the regions have been
proposed, reflecting the specificity of each area, and which can be grouped into draft
regions, namely:
 the Danube region; up to Stara Planina region;
 the Rose Valley region; Trakiya region; and the Rhodope region;
 Rila – Pirin region; and Sofia region;
 Varna region (Northern Black Sea Coast) and Bourgas region (Southern
 Black Sea Coast).
1) As seen from the figure proposed, the tourism regional zoning in many ways
coincides with the concept of the four planning regions that meet the criteria for
spatial development planning and zoning, which demonstrates and proves its validity
and practical application;
2) The Danube region - covering the area of "Danube" and much of the area of
"Stara Planina". Under the current RDA, the so called "Stara Planina" region is part of
the North-West and the North Central regions;
3) The Black Sea region - covering the area of "Varna" (Northern Black Sea
Coast) and the region of "Bourgas" (Southern Black Sea Coast), incorporating
Singurlare municipality of the Bourgas region, which is part of South Eastern region
under the RDA;
4) The Thracian region - the area of the "Rose Valley", the area of "Trakia" and
the area of "Rodopi" and a small part the area of "Stara Planina" region - part of the
Sliven region;
5) The South-West region – between the Sofia region and the Rila-Pirin region
there is complete overlapping of boundaries.

Figure 4 - A comparative scheme of the tourist /by NCTD/ and spatial zoning
(Prof. Dr. Arch. B. Borisov)

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REFERENCES
[1] Borisov,B.(2014) Draft Law on Spatial Planning and Regional
Development.“Builder 15, 11 April, pp.19-22, URL: http://vestnikstroitel.bg/wp-
content/uploads/2014/04/Stroitel-6-15-s.pdf)
[2] Borisov, B. (2014) Regulation in the investment process has become a brake on
the economic development. Builder 13, 28 March, pp.9-11 (URL:
http://vestnikstroitel.bg/wp-content/uploads/2014/03/ Stroitel-6-13-s.pdf)
[3] Concept for territorial development of tourism/CTDT/, NCRD, 2003
(URL:www.strategy.bg/FileHandler.ashx?fileId=5154)
[4] DarikNews (2009) Varna, Burgas and Dobrich to unite into one region, mayors
require, 25 March, Varna: DarikNews. URL:
http://dariknews.bg/view_article.php?article_id=341728 (Accessed on
25.03.2009)
[5] Regional Development Operational Programme for the programming period
2007-2013, Priority Axis 3 - Sustainable Tourism Development (URL:
http://www.bgregio.eu/op-regionalno-razvitie/prioriteni-osi-na-op-regionalno-
razvitie/ustoychivo-razvitie-na-turizma.aspx)
[6] Stroitelstvo Gradut (2014) The tourist regionalisation of Bulgaria is being
prepared. Stroitelstvo Gradut (iss. 27/07-13 July, 2014), pp.30-31
(http://stroitelstvo.info/print/?broi=3345)

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Borislav Yankov BORISOV

METHODOLOGICAL ASPECTS OF NORMATIVE REGULATION

OF SPATIAL PLANNING AS A SPECIFIC PART OF THE
PROFESSIONAL FIELD "ARCHITECTURE, CONSTRUCTION AND
GEODESY" IN TECHNICAL SCIENCES
Abstract: Without the necessary science-based motifs and the desired continuity in respect of the
traditional theory, practice and regulations in the territorial units, of the Bulgarian National Spatial
Development Concept /NSDC/[5] as a new statutory regulated document in the Regional Development
Act /RDA/[7]. From the very beginning of its development as a public document the NSDC as a
statutory document of national importance comes into a methodological controversy with their cognitive
and terminology apparatus of the Spatial Planning Act /SPA/[8] as well as with possibility of a more
efficient and integrated territorial and regional planning in the uniform planning documents.

Кey words: spatial planning, development concept, sustainable and integrated development

METODOLOŠKI ASPEKTI NORMATIVNOG REGULISANJA

PROSTORNOG PLANIRANJA KAO ODREĐENOG DELA STRUKA
"ARHITEKTURE, GRAĐEVINE I GEODEZIJE" U TEHNIČKIM
NAUKAMA
Rezime: Bez potrebnih naučno-zasnovanih motiva i željenog kontinuiteta u odnosu na tradicionalnu
teoriju, praksu i propise u teritorijalnim jedinicama, zakonski je regulisan Bugarski Nacionalni Koncept
Prostornog Razvoja /NSDC/ [5] kao novi dokument u Zakonu o regionalnom razvoju / RDA / [7]. Od
samog početka razvoja NSDC, kao javnog zakonskog dokumenta od nacionalnog značaja, ušao je u
metodološki sukob sa poznatom terminologijom Zakona za prostorno planiranje ACT/SPA/ [8] kao i sa
mogu noš u za efikasnijim i bolje integrisanim teritorijalnim i regionalnim planiranjem u planskim
dokumentima.

Ključne reči: prostorno planiranje, razvojni koncept, održivi integrisani razvoj

Dean of the Faculty of Architecture of VSU "Lyuben Karavelov" – Sofia, Head of the Department "Urban
Planning, Theory and History of Architecture", 1373Sofia, str. Suhodolska 175, Bulgaria, e-mail: archbb@abv.bg

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1. INTRODUCTION. ACTUALITY AND DIRECTION OF THE PROBLEM.

Arguments, concerning the obligations of Bulgaria for its integration as a member
of the EU, the justification, that the perception of "new practice" on the application of
the basic principles of the euro policy for spatial development, the requirements of the
programme for research in the area of city planning ESPON[3], the programme for
environmental protection Natura 2000, the Europe 2020 Strategy and other
documents with pan-European significance motivate the development of the NSDC. It
is set up as a new statutory regulated document and, accordingly, as part of the
general planning of the European space, notwithstanding the fact that the SPA
required for more than a decade to develop a National Comprehensive Development
Scheme /NCDS/, and even before that the Territorial and Urban Development Act [9]
required the development of Single Urban Development Master Plan /SUDMP/. In
2010, as head of the team of specialists of the National Centre of Territorial
Development /NCTD/, for the award of the Ministry of Regional Development and
Public Works (MRDPW), I finished "Methodological Guidance for the Development
of the NSDC" [2], which was adopted and published on the site of the MRDPW.
Then, in 2012, on the basis of methodological guidance, the NSDC was developed
and the SPA and the RDA were changed. In such reference, in the national legislation
the new document was entered – the NSDC. In this document /NSDC/ it is noted that
"Methodological guidance of the MRDPW for the development of the National
Spatial Development Concept of the Republic of Bulgaria by 2025, links the main
objective with the national industrial policy, which according to art. 1. of the Spatial
Planning Act should ensure the protection of the territory of the country as a national
treasure." In this sense, no doubt, it can be considered as a state spatial planning
document of national significance /meaning the theory of spatial planning/, the NSDC
reaffirms with staging for the purpose requirement of article 1 of the SPA, generates
and reproduces the methodological inconsistency between the object, the conceptual
and terminology apparatus of the SPA and the RDA, which is partially addressed
here.
2. TERMINOLOGICAL CONTROVERSY BETWEEN REGIONAL,
TERRITORIAL, STRUCTURAL AND SPATIAL DEVELOPMENT.
Whether confession recorded in the adopted by the Council of Ministers NSDC
and the mentioned here Methodological guidelines, as well as by the legislative
change in 2012, legislated this document, this theoretical material is an attempts to
analyze a part of the problems of the current complex, contradictory and even too
controversial situation of theory, practice and the regulatory framework in the field of
spatial planning in our country, including terminology, fundamental concepts,
methodology, definitions, provisions, etc.

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Figure 1 - Use in the theory and practice of different terminology for the same professional concepts
(Prof. Dr. arch. B. Borisov)

Some statements in the NSDC are indicative, explaining the hypothesis of the
present survey. "... The National Spatial Development Concept of the Republic of
Bulgaria, 2013-2025 is developed as part of the project "Programming of regional
development for the period 2014-2020", so it is not developed as a spatial planning
document pursuant to the requirement of article 100 of the then current SPA, but
rather as part of the RDA, serving the regional programming. The NSDC itself clearly
and eloquently notes that: "...The National Spatial Development Concept for the
period 2013-2025 should replace the National Comprehensive Development Scheme
(NCDS), provided in the Spatial Planning Act, which acc. to art. 100 had timely to
determine "how to achieve the goals and tasks for spatial planning at national level,
linked to the overall sustainable socio-economic development." This text follows the
NSDC is an analogue that substitutes the NCDS within the meaning of the SPA.
There is a shift in terminology, in which territorial development as a specific theory
and sharing of scientific knowledge, regulated in national classification of scientific
areas and disciplines, studied in several textbooks and many high schools, developed
in a number of scientific research papers and applied many years in practice, has been
just replaced with a new translated from abroad term – "spatial development". The
following quote from the NSDC. ".. This is the first document for the territory
planning over the past three decades, covering the entire country ...."." ...a document
which gives guidelines for planning, management and protection of the national
territory.... ", once again shows that the new document is actually a document for the
planning of the territory, i.e. a territorial development document and as such covers
and provides guidance for the same things as the NCDS of the SPA. Continuing in the
NSDC explanation that it is: "...a basic document in the latest BG legislation and
long-awaited tool for integrated planning and sustainable spatial, economic and social
development..." is made only with the change of terminology and immediately after
the quoted in the same document article 100 of the SPA, strongly advising that the
territory development is "tied to the overall sustainable socio-economic development
", i.e. it must be integrated with socio-economic development and be sustainable on
its own terms.

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3. EXAMPLES FROM THE PAST ON TERMINOLOGY CHANGES AND

INNOVATIONS
Above leads us to think about the newly announced concept "spatial development"
and whether or not it is synonymous with territorial development from the recent or
distant past? Whether it is the familiar spatial planning and territorial development,
studied at the universities or it is something else? Is it regional development or not? Is
that an attempt to introduce a new term foreignism as a replacement for the traditional
notion of something that exists with a long history in our national theory and
practice? Whether or not it formally moves the legislatively regulated documents
from one in another act with a change of their name? This Bulgarian phenomenon of
searching synonyms, but with a claim to a new theory, is not something surprising
and unknown in this professional matter. Arch. Georgi Nenov in 1927 /almost a
century ago/ in his article in the Magazine of BIAD, titled "Urbanization and
urbanism" [4] examines the meaning and use in England and France of the concepts
and terms "urbanism" and "urban development" and "urbanization". There he called
criticism of arch. Tr. Trendafilov, who, according to him, made a "careless and free
translations" of the foreign term "urbanism", shifting the meaningful and utilized by
all Bulgarians French term "urbanization" and called the Trendafilov`s actions
unreasonable innovation. (By the research of Assoc. Prof. Dr. arch. Dobrina Martins
[1]on the occasion of the 150th anniversary of the birth of architect G. Nenov). Like
this example from the past is today launched into law the concept of "space" for
territory, as the traditional notion of Bulgarian, enshrined in the Constitution of our
State, in the SPA, the Black Sea Coast Spatial Planning Act (BSCSPA), the Sofia
Municipality and Reconstruction Spatial Planning Act (SMRSPA), in many other
acts, regulations, in science textbooks, theory and practice. The literal translation of
foreign languages is not always appropriate in the specialized terminology. However,
the new document for the national "spatial development" is made in the "National
Center for Territorial Development", which confirms once again the replacement of
the existing and traditional concepts with their "translated" versions. Many other
similar examples can be given.
4. METHODOLOGICAL ASPECTS OF COMPARISON AND ANALYSIS
In this theoretical material a specialized analytical toolbox of simultaneous
terminology-text comparison and use of synonymous concepts is attached, behind
which lies the same or a similar meaning. In the same text from the below quoted
excerpts of "Methodological guidance for developing the NSDC" are lifted and bold
the concepts that are only in openness of the traditional terminology of SPA,
Terrotirial and Urban Development Act (TUDA), Planned Construction Act)[6] the
Urban Development Act[10] and are associated with unique longstanding theory and
practice in spatial planning in Bulgaria and are supplemented with pronounced italics
concepts, which in its meaning also illustrate and prove the thesis about the
possibility and the necessity to preserve the Bulgarian specific professional and
scientific productions of territorial development. This approach and comparative

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model provides a relatively simple, quick and logical conclusion about results of the
allegations concerning spatial planning and its gradual replacement, displacement,
duplication, aggravation and confusion due to translation of foreign languages
"innovations in regional and spatial problems." To illustrate more clearly this thesis it
will be necessary to stop at a couple of examples as a kind of empirical research and
to motivate shaped part of the methodology of spatial and possible legislative
changes, which would have solved this problem and would lead to the application of
the findings of this theoretical material.
4.1. Mission, Vision, Goals and Oobjectives of the NSDC Do not Differ
Principally and Substantially from Those of the NCDS Before the
Legislative Change at the RDA IN 2012.
"…In the methodological aspect, the mission of the NSDC is the spatial
/territorial/ coordination of the processes occurring in the national territory through
the creation of spatial /territorial/ basis and regulator for making not only regional,
but also the individual socio-economic sectoral planning at national level in the
context of pan-European spatial /territorial/ development, with the aim of achieving a
comprehensive, integrated planning. On the other hand, the Mission of this is the
creation of NSDC national framework for implementing the spatial /territorial/
planning of the lower territorial levels (regional, provincial, municipal), as formulated
in general guidelines and principles for the conduct of the State policy for spatial
planning.
The Vision of the NSDC, from the methodological viewpoint, should outline the
strategic expectations and priorities for future spatial /territorial/ development, and in
this sense it can be seen as a forecast model for spatial /territorial/ development
within the national territory and in the context of the European common space
/territory/.
The main objective of the NSDC in accordance with national industrial policy,
whose goal is defined in article 1 of the SPA for the territory of the Republic of
Bulgaria as a national asset, is to ensure "...sustainable development and favourable
conditions for living, work and leisure of the population". From this text it becomes
clear that there is the same goal as that of the NCDS. The specific methodological
objectives and tasks of the NSDC, that determine what kind of a document it is, and
what is it in the system of strategic planning, are the same or similar to those in
NCDS.
Integration of spatial planning with regional and sectoral planning through
territorial coordination of sectoral policies, strategies, plans and programmes which
directly or indirectly relate to spatial /territorial/ development;
Reducing budgetary imbalances in use, incl. overbuilding of the territory without
rejecting the principle of regional /territorial/ concentration policy;
Creating optimal conditions for sustainability and planning in spatial /territorial/
development/ adjustment of the violent urbanization with planned, balanced and
stimulated developing territories and impact areas/;

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Creating a territorial basis to stimulate the polycentric development of the network

of towns."
The following examples and quotes have motivated the necessary change.
4.2. Basic Methodological Guidelines and Principles For Spatial /Territorial/
Planning Are the Same or Similar to Those in the Previous Documents and
Allow the Same Terminology.
"...In the NSDC are set out spatial /territorial/ approaches for the implementation
of development policies through the application of basic methodological guidelines
and principles for conducting national spatial /territorial/ planning:
NSDC plays an important role in balancing the public and individual interests so
that to implement the priorities of the national industrial policy;
Scientific approach – in all activities and levels of spatial planning. In the process
of the NSDC developing a number of complex problems are solved – on the
formation of spatial solutions;
NSDC handled with the content management and monitoring of the two types of
objects — tangible substances (territories, settlements, infrastructure, people) and
processes (urbanization, deurbanization, a change in the status of the territories."
4.3. The coordination role of NSDC is also not new. Such is the role of the Single
Urban Development Master Plan (SUDMP) from 1977 in the Territorial
and Settlement Development Act and of the NCDS from 2001 in the SPA.
The coordination and integration are some of the main functions of spatial
planning in the traditional Bulgarian theory and practice from its
occurrence till today.

Figure 2 - Coordinative role of the NSDC / collective headed by Prof. Dr. arch. B. Borisov to
Methodological guidance for developing the NSDC (MRDPW)

"…Coordinating function the NSDC should perform and in terms of its

hierarchical territorial coherence of supranational territorial level /in the territory of
the EU, South East Europe, cross-border cooperation regions/, as well as the
territories of the regions, counties and municipalities within the national space
/territory/. The coordination role of the NSDC reflects the role of the interdisciplinary
composition of the design team, such as synthesis /complex/ project coordinator, so as
to meet the requirements for participation of sectoral departments, professional

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circles, the academic community, business and civil society representatives. The
coordination role of the NSDC is achieved and assesses the implementation of a
number of spatial /territorial/ indicators and criteria for the connection and
consistency with the other documents for regional and sectoral development..." The
following examples clarify the conclusion for essentially identical treatment of
"spatial" as territorial planning and development.
4.4. The formal translation of European "spatial" /territorial planning led to
the replacement of the traditional terminology, concepts and duplication
unnecessary repetitions of documents and plans.
From the methodological point of view it is necessary the foreign expertise to be
explored, generalized and adapted to the specific conditions at home, so the practice
of European countries showing the uniform treatment of the issues of spatial planning
with the issues of regional development /in Germany – Raumordnungsgezets, in
France – Amenagement de territoire, in Hungary – a general act on regional planning
and territorial development, etc./, to be adapted to the specific Bulgarian conditions.
The absence of EU-wide directives on spatial /territorial/ planning is offset by the
presence of common European principles and approaches, synthesized in many EU
documents, some of which in the literal translation from English led to the
terminological shifting, duplicate and changes. We can continue with the quotes for
the NSDC: "… The polycentric development in the territory of the EU… Basic
requirements for sustainable spatial planning and ...spatial /territorial/ development of
the European continent… Promoting territorial cohesion… Horizontal cooperation
with sectoral policies, which have strong impacts on the territory and vertical
cooperation in such a way that regional/ local authorities to adapt their territorial
development to measures taken to a higher level .... "
4.5. Relationships of the NSDC with the other strategic planning documents
indicate that there may be an integrated territorial national document NSTURR.
In the development of the NSDC its interconnections with all documents for the
strategic planning of regional development and sectoral strategies, plans and
programmes at different territorial levels of planning are clarified.

Figure 3 - Integration into the planning process /Prof. Dr. arch. B. Borisov

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- Methodological guidelines for the elaboration of the NSDC (MRDPW)

The integration of the different territorial levels of planning is not only possible,
but also desirable for greater efficiency, avoid the risks of inconsistencies,
simplification and reduction the time of the planning process and for better
compliance with European practices. The graphic illustrates the possibility of
unification of the territorial and regional levels of planning documents.
5. THE CONCEPTUAL THEORETICAL PROPOSALS FOR CHANGING
THE NORMATIVE REGULATION IN THE TERRITORIAL UNIT.
Some of the issues in this material may be considered as theoretical bases and
professional reasons for legislative reform in the field of spatial planning.

Figure 4 - Stages of laws in spatial planning/Prof. Dr. arch. B. Borisov

 Can the spatial planning be regarded as a separate planning theory, scientific

discipline, design and planning practice, legislation and legal regulation?
 How to create and modify the law on regional development in the transitional
period of the Republic of Bulgaria and does it have anything to do with the
structure of the territory, and the scientific theory of SPA development?
 Can the laws of Bulgaria regulate the integrated planning of the territory,
including both the spatial and regional development?
 Possible reduction in the number and types of planning documents governing
the spatial and regional development?
 What is the specific location of Sofia and other major cities in the system of
territorial and regional planning?
The answers to these and other questions, related to the normative regulation of
spatial search in the present study, explore the reasons for the problems in this part of
the scientific knowledge, looking for evidence in the traditional Bulgarian experience,
accumulated over many years, that convincing enough to be able to justify the
possible theoretical and regulatory changes, as well as to develop hypotheses about
these legal changes.

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Fiure 5 - Evolution of the spatial planning period, Prof Dr. arch. B. Borisov

In conclusion it can be observed that the new theoretical concept – a hypothesis

about the normative regulation of public documents for spatial planning in Bulgaria,
as a specific share of technical studies in the field of architecture, construction and
geodesy – is practically realizable and would result in methodological and
terminological clarification and unification of the practice by regulating the uniform
planning documents for each territorial level. The proposal for amendment is based
not only terminologically, methodologically or for reasons of more integrated
planning, as it is in most European countries, but with the well-established over time
traditions of the national spatial planning.
6. REFERENCES
[1] A research by Assoc. Prof. Dr. arch. Dobrina Martins on the occasion of the
150th anniversary of the birth of architect G. Nenov /http://zheleva-martins.com
[2] Borisov, B., Methodological Guidance for the Development of the NSDC
/http://www.mrrb.government.bg/
[3] European Obseravtion Network for Territorial Development (ESPON)
/http://www.evrofinansirane.eu/content/view/411/16/
[4] Magazine of BIAD, 1927, No. 9, p. 173-176
[5] National Spatial Development Concept (NSDC)
/http://www.mrrb.government.bg/
[6] Planned Construction Act
[7] Regional Development Act (RDA) /http://www.mrrb.government.bg/
[8] Spatial Planning Act (SPA) /http://www.mrrb.government.bg/
[9] Territorial and Urban Development Act /http://www.lawoffice-bg.net/userfiles/
[10] Urban Development Act

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Ksenija HIEL
Jovan ĐERIĆ2
Dijana BRKLJAĈ3
Aleksandra MILINKOVIĆ4

URBAN BLOCKS OF RESIDENTIAL HIGH-RISE BUILDINGS

IN NOVI SAD
Abstract: Residential high-rise buildings represent a unique phenomenon in the Vojvodina cities. Novi
Sad as the capital of the province has more than 341,000 residents, of whom about 6,000 live in
buildings with ten or more floors. These data show the importance of urban space as a function of the
extended housing for all residents of high-rise buildings. This paper explores the relationships between
built structure residential high-rise buildings and their immediate and enveloping free space within the
urban block on the territory of Liman 1-4. The current situation and spaces that permit the specific
functional processes in everyday outdoors stay of all age groups and residents in high-rise buildings is
analysed after which the guidelines for reconstruction of these spaces are proposed.

Кey words: urban space, urban blocks, residential high-rise buildings, functions.

URBANI BLOKOVI STAMBENIH SOLITERA U NOVOM SADU

Rezime: Stambeni oblakoderi - soliteri predstavljaju jedinstvenu pojavu u gradovima Vojovodine. Novi
Sad, glavni grad pokrajine ima više od 341.000 stanovnika od kojih više od 8.000 živi u soliterima sa
deset i više spratova. Ovi podaci ukazuju na znaĉaj urbanog prostora u funkciji proširenog stanovanja za
sve stanovnike solitera. U radu se istražuje odnos izmeĊu izgraĊene strukture stambenih solitera i njihove
neposredne okoline u okviru urbanog bloka na teritoriji Limana 1 – 4. Analizirano je postojeće stanje
urbanih blokova koji omogućavaju specifiĉne funkcionalne procese na otvorenom u svakodnevnom
životu stanovnika okolnih solitera za sve starosne grupe na osnovu ĉega su ponuĊene smernice za
rekonstrukciju otvorenih prostora urbanog bloka.

Ključne reči: urbani prostor, urbani blok, soliter, prošireno stanovanje.

1
Assistant Professor, Faculty of Agriculture, Trg Dositeja Obraodvića 8, Novi Sad, ksenija.hiel@polj.uns.ac.rs
2
Research Ass. Jovan Đerić, Faculty of Tech. Scinces, Trg D. Obradovića 6, Novi Sad, djeronimus@gmail.com
3
Teaching Ass. Dijana Brkljaĉ, FTS, Trg D. Obradovića 6, Novi Sad, dijana_apostolovic@yahoo.com
4
Teaching Ass. Aleksandra Milinković, FTS, Trg D.Obradovića 6, Novi Sad, aleksandrabandic@gmail.com

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1. INTRODUCTION
End of the 19th and a beginning of the 20th century brought many social changes
that have influenced the changes in the city shapes too. The new architectural trends,
the use of modern materials, the development of transport and accelerated
construction has led to the emergence of new architectural typologies. Appearance of
the elevator enabled the construction of high-rise buildings, which created a new
image of previous cities. Dramatic changes in this field have taken place in most
American cities, particularly Chicago and New York. Expresion "skyline" was used
as traditional meaning for line where earth met sky.[1] These high-rise buildings have
turned priviously calm horizontal line into recognizable images of cities. Silhouette of
buildings created by this line for some cities has become a sign of recognition -
identity. (Figure 1) European cities reduced a multi-storey building to a moderate
height according to the size of cities and population. Only after World War II
construction of skyscrapers took root in the capitals of European cities.

Figure 1 – Panoramic view - skyline of Novi Sad [2]

This new type of high-rise buildings introduced a new relationships in urban

environments, which are most often resulted in inconsistent relationships, from one
side between the surrounding existing relatively low level buildings, and from the
other side between the building and the surrounding free unbuilt space. Rationalistic
or Progressive architecture, commonly called International style is characterised by
clear forms, simple volumes and the absence of ornamentation. Genius loci as well as
the principles of vernacular architecture was rejected. In this respect, the plans of
cities acording the international stile did not have a positive attitude towards the
location, cultural or social traditions, indigenous materials and traditional construction
technology. Context of topography was incorporated in the projects in order to obtain
an adequate vista, and better position of certain premises in relation to the sun, with
the aim of increasing the health of inhabitants. The principles of the Athens Charter

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were implemented at all latitudes and lengths, in all cultures and religions as well as
socially and economically developed or less developed countries. The care of health
and hygiene was addressed as unique model in all the cities which looked like large
and spacious green areas - urban blocks bordered by roads - with erected free-
standing multi-storey buildings - skyscrapers. Traffic was separate function from
housing, work and recreation.

2. URBAN BLOCKS WITH HIGH-RISE BUILDINGS IN NOVI SAD

Principles of planning and designing of high-rise buildings represented by
members of the International Style are brought to life in the former Yugoslavia, in
which Novi Sad was not remain the exception. After World War II urban plans with
broad boulevards and zoning the city territory into the four basic functions: housing,
work, recreation and transport emerged in all countries. The traditional way of
buildings on plots with edge block construction and internal semi-public amenities
has been replaced by the principles of the International Style and the Athens Charter.
Thus, in Novi Sad was created residential areas such as Satelit, Grbavica, Limani,
Bistrica, and strips along the Boulevar Oslobodjenja. (Figure 2 & 3) The new parts of
the city were formed on the surfaces of relatively large urban blocks with a free-
standing building levels from 4 to 18 floors. The size of the urban blocks vary from
2ha to 16ha, in the form of various geometric shapes, but usually square or
rectangular. Typology of urban blocks in relation to the construction system varied
from semi-open to open spece, with facilities withdrawn from the street roads. Free-
standing buildings were surrounded by children's playgrounds and green areas. With
increasing the standards and the development of car industry a part of the green
spaces inside the urban blocks were slovely turned into a parking area. Garages was
sporadic and mostly those spaces were part of the ground floor of buildings. In this
way, pedestrian passages were even more separated from the streets and apartment
blocks became a "dormitory."

Figure 2 and 3–Liman 3 before first buildings in 1970.(left) and Narodnog fronta Street in
early 1980 (right)[3]
The critics have been pointed to the drawbacks of this type of planning and design.
They warned that urban solutions are mainly beautiful drawings on the paper as a
combination of rectilinear and curvilinear geometric shapes, and that real life in these
areas is a major threat to the urban morphology, which resulted in the abolition of

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public facilities along the street movements. Rectilinear forms of urban development
plans were the principle of design in a landscape architecture too. (Figure 4 and 5)
Large grassy areas of free space between the buildings are supplemented by children's
playgrounds and sports fields usually for basketball. The winding paths that connects
the fields with pedestrian flow along the street roads were the only organic forms in a
space. Marginal zones of urban blocks and parking spaces are articulated with the
strict lines of the tree avenue, while the bushy species appeared as a supplement to the
remaining free spaces. Thus formed groups of deciduous and conifer trees have to
meet the basic sanitary and hygienic conditions to protect the inhabitants living in
these urban blocks from harmful micro climate. The effect of the reduction of air
pollution from exhaust gases as well as reduction of noise that reaches from the
surrounding roads was most often achieved. The variation of equippment was not the
dominant factor in planning these urban blocks. A decorative and aesthetic role was
dominant in relation to the content-functional design of the urban block but residents
are not properly enabled with functions of every day needs. The main ideas of the
General Urban Plan (GUP) in Novi Sad from 1963 was achieved until the mid
seventies when a new GUP from 1974 was adopted. Although urban policy strive to
human relationships in a space (GUP from 1985), the high-rise building were built
until the end of the eighties, mainly under the influence of Modern movement and
socialistic concept of housing in the cities.

Figure 4 and 5 – Conceptual solution from 1977 of urban blocks of Liman 3 between Bul C. Lazara
(north), Despota Stefana (south), Šekspirova Street (east) and Balzakova Street (west) [4]and satellite
photo from 2015 (right figure)[5]
During the last decade of the 20th century and the first decade of the 21st century,
the traditional understanding of the urban blocks as a closed space defined with
buildings on the edge has become the basic principle of the reconstruction of existing
urban structures. Yet this principle was not applied in all segments, in order to build a

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more humane living spaces, especially when it involved the reconstruction of existing
housing blocks with single-family housing typology. Disadvantages of this type of
planning is evident in Grbavica, Nova Detelinara and parts of Podbara. Construction
of the high-rise buildings again ranks in the zoning plans, but as sporadic "planted"
facilities in enclosed or semi-enclosed urban blocks. These facilities are in contrast to
previous built as residential-commercial or exclusively commercial buildings. The
ground floors are with mainly service-commercial content that provide the physical
connection to the surrounding public space of the street. High-rise buildings are again
gaining the importance role in urban development plans, and the image of the city has
continued to change from plain and humane scale city to city with disproportion,
overcrowding, the vast surface parking places, traffic chaos and sporadic
"architectural monuments".

3. CHARACTERISTICS OF URBAN BLOCKS WITH HIGH-RISE

BUILDINGS IN THE LIMAN 1-4
The cityscape of Novi Sad during the sixties of the 20th century was an image of a
typical Pannonian lowland settlements of major proportions. According to GUP from
1963 the spatial and functional development of the city envisaged the development
primarily on the free surfaces (south-Limani, west-new residential area and northern
parts around the new railway station with the area along the canal-Klisa) as well as
the reconstruction of the existing urban tissue. The construction of the first high-rise
building in Liman 1 in Veljko Petrović Street in late fifties began to alter the former
image of peaceful plain low-rise city. (Figure 6) These three towers with 11floors and
intensive construction of high-rise residential buildings, in other parts of the city
during seventies and eighties, has definitely changed the image of Novi Sad, which
has now grown into a modern metropolis on the banks of the Danube. (Figure 7) By
the end of the 20th century all the residential high-rise buildings at Liman1-4 were
built and this part of the city became the most densely populated part of the city with
more than 32,000 residents. [6]

Figure 6 and 7–Firs toll building in Liman 2.(left) a view to a south-west part of Novi Sad (right)[2]

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In the analysed urban blocks with high-rise buildings on Liman 1-4 lives about
6,600 residents in 2,540 housing units. Structure of housing units varies from studio
area about 30m2 one bedroom flat 40 m2, two bedroom flat with about 55m2 up to
three-bedroom and four-bedroom flats with maximum floor area of 88m2. [7] By
reviewing an urban plans and analysis of the present situation on the site a certain
similarities or absence of identity was observed. Six high-rise buildings on the corner
of Šekspirova Street and the Narodni front Street are similar to the group of high-rise
buildings in the urban block closer to the corner of Balzakova and the Narodnog
fronta Street. Architecture of high-rise buildings in the Boulevard of Despota Stefana
is identical to the high-rise buildings at 1300 kaplara Street. This repetition is evident
in the landscaping of the same analysed urban blocks. Abolition of the traditional
street frontage with the buildings on the edge of the urban blocks as well as grouping
the buildings around a common "centre" within open and degraded urban block has
led to the impression of loneliness and discontinuity. [8] Such disposition of facilities
and planning of free space around the buildings create an ideal image of unity and
facilities, but only in the drawings and plans.
The reality of space and lives of the citizens in these areas point to a many
shortcomings. Results of the survey conducted among residents [9] indicate a strong
dissatisfaction of respondents, regardless of their age and gender. Most of the
negative comments were related to: flats on the upper floors, lack of communication
with the surrounding space-nature, the disorganisation and lack of equipment, cars
overcrowding, lack of space for socialising and gatherings, security especially for the
youngest children and the elderly, as well as for the all other users of the urban block.
Solutions to some problems has been seen in: underground garages, improved design
and organisation of free surfaces, better-maintained greenery and active participation
of inhabitants in decision-making process about how the reorganisation of the urban
block should look like.
In order to look better into the current situation of the observed urban blocks with
residential high-rise buildings a SWOT analysis was carried out. Although this
analysis is made for each urban block with high-rise buildings in particular, some
conclusions that are common to all analysed areas can be highlighted. The aspect of
strenght is reflected in the fact that these buildings represents an urban landscapes,
have a good position in the urban structure of the city, has a good connection with the
other parts of the city, as well as the entire territory of Liman 1-4, especially when it
comes to lines of the public transport service. Strengths are reflected in the excellent
view from units especially the upper floors as well as in the contrast achieved with
suraunding built structures. Special strenght is existing greenery with diversity of
species and categories of green areas. Weaknesses are reflected in old age building
structures, precast concrete facade elements affecting the drastic reduction in energy
efficiency and increasing the surface of the radiant heat in the summer months.
Elements of street furniture are old, neglected or completely collapsed and are
insufficiently widespreaded in the analysed areas. Parking spaces are available in
sufficient numbers, parking spaces for bikes are sporadic with absence of bike paths

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inside of the urban blocks. A large number of spontaneous footpaths had not paved.
The safety of inhabitants is reduced due to inadequate lighting or its complete
absence. In all analysed parts of urban blocks it is noticeably inadequate parking cars
which are often parked on the pedestrian walkways and green areas. Many green
areas are overcrowded due to inadequate conduct of a greenery and maintanance.
Entrances in to the buildings are very ofen inaccessible. The potential or possibilities
of these urban blocks indicate the following facts. Some high-rise buildings represent
the unique architecture and a recognizable landmark in the city. The location offers
opportunities for exlusive residence with the benefit of proximity to downtown and
the University campus as well as numerous services and commercial activities. The
proximity of Spens, Liman Park, the beach on the Danube Štrand, Ribarsko ostrvo on
the Danube, Djaĉko igralište playgrounds and walkways along the river Danube are
indispensable convenience when it comes to recreation and sports. For the realisation
of any plans in terms of reconstruction and revitalization of the analysed parts of
urban blocks threats from SWOT analysis represent a major obstacles. They are
reflected in inadequate management and maintenance of facilities and the surrounding
area. Inadequate purpose and use of the land within and on the borders of urban
blocks makes their rearrangement in both functional and aesthetic terms. A significant
threat to any type of physical interventions are the lack of financial resources and
ownerhips refers to buildings (construction of the underground garage, restoration of
facades, etc.).
Green urban blocks with free-standing multiple family dwellings in form and
function of the green blocks, and for its natural and cultural values represents a green
areas for everyday use. [10] In this sense, both functional and aesthetic values such as
observed areas must meet many and varied demands of their users. Bearing in mind
the age, gender, cultural, religious and many other differences that distinguish the
inhabitants of urban blocks suggests the following changes. Retention of existing and
opening a new vistas in places where it is possible, with removing of existing barriers
is required. Planting a new single and high massif trees is possible only in the zones
of "blind" facade and places in the interior of the block where they will not obstruct
the view from the flats. The principles of universal design must be incorporated in all
aspects of the intervention to the interior of buildings. The existing physical barriers
must be removed, and urban blocks with displacement field must be set up with ramp
slopes up to 5%. For all pedestrian communication should foresee the installation of
tactile paths. The interior of the urban blocks on the meeting places of pedestrian and
vehicular traffic should clearly emphasize with the colors and types of pavingas well
as with the light. Children and sports facilities must be adequately equipped with the
following urban furniture. A number of benches must be protected from weather
conditions (sun, rain, snow, wind). Construction of the underground garage will allow
liberation of a large area presently under parking areas and their access roads. Roofs
of new garages should be designed for the principles of intensive greening with
functional amenities to meet the needs of the inhabitants.

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The introduction of new pedestrian and cycle path communication is imperative

during any intervention in these urban blocks. Spaces for temporary parking of
bicycles must be planned in front of the each entrance to the building, as well as near
all playgrounds and areas for relaxation. Permanent parking and accommodation of
bicycles is necessary to provide in underground garages or rooms on the ground floor
(basement) of the buildings that are accessible by ramps. The entire above
communication path is required to adequately illuminate within urban blocks and
along the streets that creates the bloc's borders. The facades should be restored by
using the materials that will improve the energy efficiency of housing units and
reduce the temperature at the micro level during the summer. Installing external air
conditioning units should be unified or replaced with implementation of a unique
system of air-conditioning within buildings.

4. CONCLUSION
Construction of residential high-rise buildings as a special, architectural structures
brings the new relations in the urban tissue of Novi Sad. Urban blocks in which there
are such buildings were and remain as open urban blocks with a relatively large free
spaces - green area with various functions - usually playgrounds. Such open urban
blocks with a free set buldings that characterize the openness, the failure to consider
the boundaries, a relatively large green areas and accessibility to all citizens, differ
from traditional urban structure of closed or semi-closed urban blocks. In this sense as
the specificity of the urban matrix of Novi Sad these urban blocks and their high-rise
buidings must be retained and preserved from decay and transformation.

5. REFERENCES
[1] Kostof S. 1999. The City Shaped: Urban Patterns and Meanings Through Histor.,
New York, Thames & Hudson.
[2] Authors photo
[3] https://www.google.com/search?q=stari+novi+sad
[4] Archival record of Faculty of Agriculture, Department of fruit science,
viticulture, horticulture and landscape architecture
[5] Google Earth
[6] http://katastar.rgz.gov.rs/KnWebPublic/
[7] http://juznobacki.okrug.gov.rs/sr/novi_sad_infrastruktura.php?lang=lat
[8] Supek R. 1987. Grad po mjeri ĉoveka. Zagreb, ITRO Naprijed
[9] The survey conducted as part of research for the Strategy of the green spaces of
the City of Novi Sad 2015-2030. Faculty of Agriculture, Department of fruit
science, viticulture, horticulture and landscape architecture in 2013 and 2014.
[10] Anastasijević H. 2002. Podizanje i negovanje zelenih površina, Beograd,
Šumarski fakultet.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Yuliya ILIEVA

NEW GEOMETRICAL FORM-FINDING METHOD FOR

CREATING TENSEGRITY MODULES
Abstract: The creation of new forms is one of the current trends in the development of tensegrity
structures. The reviewed form-finding methods can be classified as geometrical and mechanical. The
latter is subdivided into statical and kinematical. The present paper describes a new geometrical form-
finding method for creating tensegrity modules. It was named “V plus V” manipulation. Following these
rules, a large class of tensegrity units can be designed. The invention was applied to cubic modules and
to a twisted truncated pyramid with square bases. The created tensegrity cells comprise four struts. The
compression elements can be clockwise or counterclockwise twisted.

Кey words: Tensegrity, tensegrity modules, form-finding methods, “V plus V” manipulation.

NOVA GEOMETRIJSKA METODA PRONALAŽENJA FORMI ZA

KREIRANJE TENSEGRITI MODULA
Rezime: Kreiranje novih formi predstavlja jedan od trenutnih trendova u razvoju tensegriti konstrukcija.
Revidirane metode pronalaženja formi moguće je podeliti na geometrijske i mehaničke. Kasnije je
izvršena podela na statičke i kinematičke. U radu je prikazana nova geometrijska metoda pronalaženja
formi za kreiranje tensegriti modula pod nazivom “V plus V” manipulacija. Na osnovu ovih pravila,
moguće je kreirati tensegriti jedinice visoke klase. Predmetni pronalazak je primenjen na kubnim
modulima i na uvrnutoj zarubljenoj piramidi sa kvadratnom osnovom. Kreirane tensegriti ćelije čine
četiri razupirača. Pritisni elementi mogu biti uvrnuti u smeru kazaljke na satu ili suprotno.

Ključne reči: Tensegriti, tensegriti moduli, metode pronalaženje formi, “V plus V” manipulacija.

Chief Assist. Prof. Dr. Arch., University of Structural Engineering & Architecture “Luben Karavelov”, 175
Suhodolska Str., 1373, Sofia, Bulgaria, yuliya_ilieva@vsu.bg

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1. INTRODUCTION
Tensegrity structures date back to the twentieth century. They are lightweight
spatial reticulated structures, composed of discontinuous struts in compression inside
a net of continuous cables in tension, in such a way that the compression components
do not touch each other. These systems are in a self-equilibrium and self-stress state
with any self stress level. Thus their stability and stiffness are ensured. Buckminster
Fuller, David Emmerich and Kenneth Snelson are considered the creators of
tensegrity structures. The term “tensegrity” reveals the mechanical behavior of this
type of systems as it derives from the words tension and integrity. It was first
proposed by the American architect and engineer Buckminster Fuller [3]. Nowadays
tensegrities are attracting the attention of architects and engineers with their
remarkable configurations and potential for further improvement in architectural and
technical aspect. These kinds of structures have been taken into account in the last
years with increasing frequency for the construction of canopies, roofs, covers,
bridges, furniture, interior elements and etc.
The creation of new forms is one of the current trends in the development of
tensegrity structures. Scientists from different parts of the world are working on this
problem. The reviewed form-finding methods can be classified as geometrical and
mechanical. The latter is subdivided into statical and kinematical. The present paper
describes a new geometrical form-finding method for creating tensegrity modules. It
was named “V plus V” manipulation. Following these rules, a large class of tensegrity
units can be designed. They have similar characteristics in terms of geometry and
topology. The invention was applied to cubic modules and to a twisted truncated
pyramid with square bases. The created tensegrity cells comprise four struts. The
compression elements can be clockwise or counterclockwise twisted.

2. EXISTING METHODS FOR CREATING TENSEGRITY MODULES

The process of defining the geometrical configuration of tensegrity structures is
called form-finding. It is a key step in their design. Buckminster Fuller, David
Emmerich and Kenneth Snelson used mainly regular, convex polyhedra as the basis
for finding new configurations. This purely geometric research resulted in a large
number of tensegrity modules which were later classified by Pugh [13] by identifying
three pattern types: diamond, circuit and zig-zag.
In their patents Fuller, Emmerich, Snelson, Wemyss and Liapi described identical
tensegrity units composed of three rods, which were spirally twisted in the vertical,
and a network of connecting cables [8]. In compliance with the above-mentioned
manner of spatial arrangement, groups of similar tensegrity modules could be
obtained by increasing the number of compression struts - four, five, six and so on.
Aleksandrova [2] achieved architectural expression by twisting thicker and thinner
rods or rod-shaped elements on a spherical surface. She et al. designed a high
building type “skyscraper” in which similar spherical surfaces were used [1].

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Tibert and Pellegrino [15] classified the existing mechanical form-finding methods
for tensegrity structures into two broad families, kinematical and statical methods.
Kinematical methods determine the configuration of either maximal length of the
struts or minimal length of the cable elements, while the length of the other type of
elements is not allowed to vary. They are best suited to obtain only configuration
details of structures that are already essentially known. The second category contains
statical methods, which determine the possible equilibrium configurations of a
tensegrity structure with a given topology, i.e. a given number of nodes and
connecting elements between them.
Raducanu [14] proposed a new methodology for creating tensegrity grids by
means of the use of interdependent expanders instead of independent autostable
modules, applying topological and geometrical relationships between them. He
proposed three different types of expanders depending on their shape: V, Y and Z
(Fig. 1). Thus new grids never found before were obtained. The Z - expander is
formed by closed chains of n contiguous struts going zigzag between the upper and
lower layer of the double-layer tensegrity grids (DLTG). When applied to different
geometry the V – expander can be used for the generation of bi-, tri- and quadri-
directional tensegrity grids (Fig. 1 a, b, c). Motro [12] described them either by their
2V expander or by their cubic elementary stitch, but also by frames. Thus, all of those
edge cables form a continuous zigzag pattern along the border of the grid, visible in
the upper middle zone. The mutual weaving of zig-zag lines, situated in two, three or
four intersecting directions may also be used as a construction principle for this type
of structures. First Snelson began to apply the zigzag arrangement of rods in
tensegrity structures in 1960 [7].

a) b) c) d)
e)
Figure 1 – Tensegrity expanders: a ), b), c) The V – expander; d) The Y – expander; e) The Z -
expander

Gomez et al. [5] proposed a new technique, known as Rot-Umbela manipulation.

It permits conventional double-layer grids (DLG) to be transformed into tensegrity
grids. Thus opening and endless catalogue of new and unknown forms could be
obtained. Applied to polyhedra, Umbela Manipulation is defined as an operation that
consists of an opening in a given direction in the space in such a way that we can
obtain a regular polygon with its vertices placed in a plane perpendicular to the
chosen direction [4]. In the case of a grid or tessellation, Rot-Umbela manipulation is

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defined as a particular Umbela manipulation in which the vertex of a grid is converted

to several nodes linked together and usually rotated around the original vertex. The
main parameters and sequence for the Rot-Umbela manipulation are given in Fig. 2.
Final shape and rotation would be defined by the initial conditions imposed to
geometry and state of self-stress applied to the structure. When talking about DLGs,
Rot-Umbela manipulations can be applied to just one of the two layers or both, as
well as to all the vertices of the grid or just some ones.

a) b) c) d)
Figure 2 – Main parameters and sequence for the Rot-Umbela manipulation in a grid: a)
Original configuration of the DLG; b) Opening (a) of the original upper vertex and
generation of six new vertices; c) Rotation (r) of the new vertices around the original vertex;
d) Reorganization of the top cables to avoid interferences

Tensegrity modules, composed of three pairs of mutually orthogonal compression

members and a network of connecting cables were first discovered by Emmerich as
noted by Ilieva [8]. Christopher Kitrick associated their morphology with the
geometry of icosahedron. Tensegrity units can be obtained as a result of a
modification of the so-called expanded octahedron. In Tor Vergata footbridge [11]
four of the parallel struts are vertical. The module enjoys a wide “cross-sectional”
space.
Researchers from different countries have been using tensegrity models over the
last thirty years in order to reveal the structural features of particular representatives
of flora and fauna as well as to illustrate their mechanical behavior at both
microscopic (cellular) and macroscopic (anatomical) scales. Nature’s perfect
organization can inspire visual design and invention. It can also be used to seek for
innovative tensegrity structures for application in architecture and construction [9]. In
the paper “Innovative Tensegrity Models Generated on the Basis of Representatives
of Living Nature” [9] different innovative biotensegrity models were presented and
analyzed by Ilieva.

3. GENERATION BY “V PLUS V” MANIPULATION

3.1. “V plus V” Manipulation
The present paper describes a new geometrical form-finding method for creating
tensegrity modules. It was named “V plus V” manipulation. Following these rules, a

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large class of tensegrity units can be designed. In this research the invention was
applied to cubic modules and to a twisted truncated pyramid with square bases, but it
could be used for any convex polyhedra. Each of the created tensegrity cells
comprises four struts. This fact gives us reason to call the modules Quastruts. The
term was first introduced for tensegrities by Gomez et al. [6]. If we look at the plan
view of the elementary unit we will see that there are two pairs of bars (marked with
red and blue in the examples below). They seem like two intersecting letters “V” and
are twisted clockwise or counterclockwise in the vertical direction. In space
compression elements pass each other between the upper and lower layers of the
body. Thus the created basic modules comply with the definition given by Fuller [3]
for tensegrity. They consist of discontinuous compressive members and continuous
tensile members. The number of rods that meet at the same node is equal to 1. The
bottom tips of the two “V” letters do not match. The end of each strut can be a vertex
of one of the bases of the module or a point of one of the edges of its bases. The
tensegrity cell may have a certain rotational symmetry depending on the location of
its elements.
3.2. Design Results
In this part of the research the design results after the application of the “V plus V”
Manipulation to two cubic modules and to a twisted truncated pyramid with square
bases can be seen. The generated tensegrity modules have two layers, a lower and an
upper, that consist of cables. Both layers are connected together by an intermediate
layer of compression struts and tension wires, arranged diagonally or vertically. The
obtained units could be implemented for the design of DLTGs, but also for another
kind of structures, like pedestrian bridges or light canopies.
The module presented in Fig. 3 is included within a cube. The blue compression
bars connect a vertex of one of the bases of the cube (i. e. the bottom) to the midpoint
of the opposite edge of the other layer. The red struts connect a vertex of one of the
bottom bases of the unit to the opposite vertex of the other top base and a vertex of
one of its top bases to an adjacent vertex of the other bottom base. They can also be
defined respectively as a body diagonal of the cube and as a diagonal of one of its
sides. The top and bottom cables outline a trapezoidal shape (Fig. 3). There are also
additional diagonal tensile elements at both of the bases of the cube, which cross each
other. So the number of the cables of each base of the elementary unit is equal to 5.
The number of the vertical and diagonal cables of the tensegrity module is equal to 4.
They extend from each of the nodes of a layer (i. e. the bottom) that reaches a
compression element to the corresponding node corner of the other layer (i. e. the top)
and vice versa. There is no twist angle between the upper and lower sides of the cube
that simplifies the implementation of the basic unit.

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a) b) c)
Figure 3 – A 4-strut cubic tensegrity module: a) architectural model; b) axonometry; c) top
view

My second tensegrity module, generated by applying the “V plus V”

Manipulation, was also included within a cube [10]. The compression bars connect a
vertex of one of the bases of the cube (i. e. the bottom) to the midpoint of an adjacent
opposite edge, but of the (top) opposite base. The bottom and the top cables can form
a S-shape or a Z-shape. As a result, two different tensegrity modules are obtained
with the same configuration of rods, but different distribution of wires. The number of
the cables on each base of the cube is equal to 4. The S-shape net of wires of the
bottom layer is rotated by 90˚ relative to the superior one. The Z-shape meshes of
bottom and top cables are parallel to each other, but are turned upside down relative
to one another. The number of the diagonal cables of the Quastrut is equal to 4. They
lie in vertical planes and extend from each of the intermediate nodes of a layer (i. e.
the bottom) that reaches a compression element to adjacent node corner of the other
layer (i. e. the top) and vice versa. The Quastrut has a rotational symmetry of 180˚,
instead of 90˚, that the conventional four-strut tensegrity prisms have. There is no
twist angle between the upper and lower sides of the cube.
The basic tensegrity module that is shown in Fig. 4 is included within a twisted
truncated pyramid with square bases. Its layers are rotated at an angle of 45˚. The
compression bars connect a vertex of one of the bases of the prism (i. e. the bottom)
to an opposite vertex of the other (top) base or a vertex of one of the bases to the
midpoint of the opposite edge of the other layer. The top and bottom cables outline a
trapezoidal shape. The number of the cables on each base of the elementary unit is
equal to 4. The number of the diagonal cables of the tensegrity module is equal to 8.
They extend from each of the nodes of a layer (i. e. the bottom) that reaches a
compression element to the adjacent node corner of the other layer (i. e. the top) and
vice versa.

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a) b) c)
Figure 4 – A 4-strut twisted truncated pyramid tensegrity module: а) architectural model; b)
top view

4. CONCLUSION
In the current paper the existing methods for creating tensegrity modules were
reviewed. A new geometrical form-finding method named “V plus V” manipulation
was presented. It was proven that these rules may be used for the generation of
different double layer tensegrity modules from prisms (cubes) and truncated pyramids
with square bases. The possibilities for creating innovative units are open. The
application of the invention to other convex polyhedra should be the subject of further
research. Structural stability analysis of the proposed modules also has to be done.

ACKNOWLEDGEMENTS
The author gratefully acknowledges the financial support provided by the
University of structural engineering & architecture “Lyuben Karavelov” – Sofia for
participation in the conference. The presented results are part of my work on the
scientific research project entitled: „Innovative methods for creating tensegrity
structures for applications in architecture“.

REFERENCES
[1] Aleksandrova L., Y. Aleksandrov, L. Mancheva and Mustafa Hasan (2014).
Pacific Heights Ocean Skyscraper Architectural Competition – 2014. Project №
1000001341. <http://www.superskyscrapers.com>.
[2] Aleksandrova, L. (2015). Similarity of Twisted and Spun Geometric Shapes,
Designed for Implementation of High-rise Buildings of the Skyscraper Type.
Proc., 15th International Scientific Conference VSU'2015, University of
Structural Enineering and Architecture (VSU) “L. Karavelov”, Sofia, volume III,
pp. 27- 32.
[3] Fuller, B. (1962). Tensile-integrity Structures. US Patent No. 3,063,521.

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[4] Gancedo Lamadrid E., J. Gómez, J. González and J. Menéndez (2004). A New
Method to Obtain and Define Regular Polyhedra. Geometriae Dedicata, 106 (1),
pp. 43–49.
[5] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado (2012). Novel
Technique for Obtaining Double-Layer Tensegrity Grids. International Journal
of Space Structures, volume 27, issue 2 & 3, pp. 155-166.
[6] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado (2013). Innovative
Families of Double-Layer Tensegrity Grids: Quastruts and Sixstruts. Journal of
Structural Engineering © ASCE, volume 139, pp. 1618-1636.
[7] Ilieva, Y. (2014). Genesis and Development of Tensegrity Structures. Proc., 14th
International Scientific Conference VSU'2014, University of Structural
Enineering and Architecture (VSU) “L. Karavelov”, Sofia, pp. 55-60.
[8] Ilieva, Y. (2014). Innovative Solutions for Designing Tensegrity Structures.
Proc., International Conference on Civil Engineering Design and Construction
(Science and Practice), Varna Free University “Chernorizets Hrabar”, Varma,
pp. 394-401.
[9] Ilieva, Y. (2014). Innovative Tensegrity Models Generated on the Basis of
Representatives of Living Nature. Proc., 2nd Conference for PhD students in
Civil Engineering CE-PhD 2014, Technical University of Cluj-Napoca in
partnership with Academy of Technical Sciences of Romania & SEnS Group,
Cluj-Napoca, pp. 668-675.
[10] Ilieva, Y. (2015). Planar Double-layer Tensegrity Grids Composed of
Elementary Cubic Modules. Proc., 2nd International Conference with Exhibition
S.ARCH, Environment and Architecture, RENECON International, Budva, pp.
409.1-409.8.
[11] Micheletti, A. (2012). Modular tensegrity structures: the TorVergata footbridge.
Mechanics, Models and Methods in Civil Engineering, LNACM 61, pp. 375-384.
[12] Motro, R. (2003). Tensegrity: Structural Systems for the Future. London and
Sterling, VA: Krogan Page Science.
[13] Pugh, A. (1976). An Introduction to Tensegrity. University of California Press,
Berkeley, California.
[14] Raducanu, V. (2001). Architecture et système constructif: Case de systémes de
tenségrité. Ph.D. thesis, Université de Montpellier II, Montpellier, France.
[15] Tibert A. G., S. Pellegrino. Review of Form-Finding Methods for Tensegrity
Structures. <http://www.pellegrino.caltech.edu/publications/review>.

[477]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Yuliya ILIEVA

DESIGN OF PLANAR DOUBLE-LAYER TENSEGRITY GRIDS

COMPOSED OF BASIC CUBIC MODULES
Abstract: Double-layer tensegrity grids (DLTGs) can be defined as self-stressed, stable spatial
reticulated systems based on tensegrity principles. Their top and bottom surfaces are made by two
parallel networks of tensile members, that nodes are linked by vertical and/or inclined web members
under compression and tension. The genesis of DLTGs coincides with the appearance of the first
tensegrity structures in the twentieth century. The aim of the present paper is to create a new family of
planar DLTGs composed of novel four strut cubic modules. Additional cables can be used in order to
make the overall stiffness of the basic cells and their mosaic assemblies greater. Special attention was
paid to the variants of mutual juxtaposition of the basic tensegrity modules and their joints.

Кey words: Tensegrity, tensegrity structures, planar double-layer grids, cubic modules.

KREIRANJE PLANARNIH DVOSLOJNIH TENSEGRITI REŠETKI

SASTAVLJENIH OD OSNOVNIH KUBNIH MODULA
Rezime: Dvoslojne tensegriti rešetke (DLTGs) mogu se definisati kao samoopterećeni, stabilni prostorno
umreženi sistemi, zasnovani na tensegriti principima. Njihove gornje i donje površine sačinjene su od
dve paralelne mreže zateznih elelemata, čiji su čvorovi povezani vertikalnim i/ili nagnutim mrežnim
elementima pod pritiskom ili zategnutim. Pojava ovih rešetki podudara se sa pojavom prvih tensegriti
konstrukcija u XX veku. Cilj rada jeste kreiranje nove familije planarnih DLTGs sastavljenih od
osnovnih kubnih modela. Moguće je upotrebiti dodatne kablove u cilju povećanja ukupne krutosti
osnovnih ćelija i njihovih mozaičnih sklopova. Posebna pažnja je posvećena varijantama uzajamne
jukstapozicije osnovnih tensegriti modula i njihovih veza.

Ključne reči: tensegriti, tensegriti strukture, planarne dvoslojne rešetke, kubni moduli.

Chief Assist. Prof. Dr. Arch., University of Structural Engineering & Architecture “Luben Karavelov”, 175
Suhodolska Str., 1373, Sofia, Bulgaria, yuliya_ilieva@vsu.bg

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1. INTRODUCTION
Double-layer tensegrity grids (DLTGs) can be defined as self-stressed, stable
spatial reticulated systems based on tensegrity principles. Their top and bottom
surfaces are made by two parallel networks of tensile members, that nodes are linked
by vertical and/or inclined web members under compression and tension [2]. As
modular structures, DLTGs are composed of basic tensegrity units. Their variety is
based on the configuration of the assembling members and on the way in which these
components are connected to each other to form a system. Most tensegrity modules
have a prismatic or pyramidal shape with triangular, square or pentagonal bases.
DLTGs for application in architecture and building construction can have planar
surfaces, surfaces of single curvature or double curvature. Among tensegrity forms,
double-layer tensegrity grids, composed of tensegrity simplexes, appear most suitable
as structural forms.
One recent report [4] investigated in detail the genesis and the contemporary
trends in the development of planar tensegrity grid structures. Their geometric
characteristics, basic tensegrity modules, which they are composed of, and patterns of
assembly were also examined thoroughly. The genesis of DLTGs coincides with the
appearance of the first tensegrity structures. This is the period of the 50s and 60s of
the last century.
The aim of the present paper is to create a new family of planar double-layer
tensegrity grids composed of novel four strut cubic modules. The principles of
combinatorial composition were implemented. The basic cells are at a stable self-
equilibrated state and so are their mosaic assemblies. Additional cables can be used in
order to make the overall stiffness of the DLTGs greater and to receive closed
configurations. Special attention was paid to the variants of mutual juxtaposition of
the basic tensegrity modules and their joints. Some examples of innovative DLTGs
were presented. At the end of the present paper conclusions were summarized. They
point out the main findings of the study and further research that should be done on
this subject.

2. DESIGN OF INNOVATIVE PLANAR DLTGS

In order to reveal the design procedure for generating new DLTGs, the unit
geometry, the method of defining planar configurations and design results were
successively explained.
2.1. Unit Geometry
The basic tensegrity module is included within a cube (Fig. 1). It has two layers, a
lower and an upper, that consist of cables. Both layers are connected together by an
intermediate layer of compression struts and tension wires, arranged diagonally or
vertically. If we look at the plan view (Fig. 1 c) of the elementary unit we will see that
there are two pairs of bars (marked with red and blue). They seem like two

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intersecting letters “V” and are twisted in the vertical direction. The blue compression
bars connect a vertex of one of the bases of the cube (i. e. the bottom) to the midpoint
of the opposite edge of the other layer. The red struts connect a vertex of one of the
bases of the prism (i. e. the bottom) to the opposite vertex of the other (top) base or a
vertex of one of the bases of the prism (i. e. the top) to an adjacent vertex of the other
(bottom) base. They can also be defined respectively as a body diagonal of the cube
and as a diagonal of one of its sides. The number of struts is equal to 4. This fact
gives us reason to call the module Quastrut. The term was first introduced for
tensegrities by Gomez et al [3]. The top and bottom cables outline a trapezoidal shape
(Fig. 1). There are also additional diagonal tensile elements at both of the bases of the
cube, which cross each other. So the number of the cables of each base of the
elementary unit is equal to 5. The number of the vertical and diagonal cables of the
tensegrity module is equal to 4. They extend from each of the nodes of a layer (i. e.
the bottom) that reaches a compression element to the corresponding node corner of
the other layer (i. e. the top) and vice versa. The obtained unit was used for the design
of the planar double-layer tensegrity grids, described in this paper. Additionally, I
tried to get new variations of tensegriy modules that have the same configuration of
rods, but different distribution of wires at the bases (Fig. 1, 2). Each lower and upper
layer of the second example includes only 4 cables that outline a trapezoidal shape
(Fig. 2). The module showed poor spatial stability. It was not used for further
research. The third studied example had cables of the layers forming a Z-shape. It
also was not in a stable self-equilibrated state.
The proposed basic module (Fig. 1) complies with the definition given by Fuller
[1] for tensegrity. It consists of discontinuous compressive members (struts) and
continuous tensile members (cables). The number of rods that meet at the same node
is equal to 1. Additionally, there is no twist angle between the upper and lower sides
of the cube that simplifies the implementation of the basic unit.

a) b) c)
Figure 1 – A 4-strut cubic tensegrity module: a) architectural model; b) axonometry; c) top
view

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a) b) c)
Figure 2 – Another embodiment of the 4-strut cubic tensegrity module: a) architectural model;
b) axonometry; c) top view

2.2. Geometric Method of Defining Planar Configurations

In this part of the scientific research I explore the compositional possibilities for
generating automatically different planar DLTGs composed of the above defined
four-strut tensegrity module. The applied connection method is edge-to-edge. In the
paper „Planar Double-layer Tensegrity Grids Composed of Elementary Cubic
Modules“ [5] Ilieva proposed several different patterns of assembly for edge-to-edge
connection. Two adjacent elementary units can be connected by a full or a partial
overlap of their upper and lower base sides. In this scientific research I explored the
example of a full overlap of the upper and lower base sides. The arrangement of the
basic modules along x and y is the same and this facilitates the implementation. In
turn, two adjacent tensegrity units can be without a mutual rotation or with a rotation
equal to 90˚, 180˚ or 270˚ relative to the plane, set by their bases. Variants of
additional rotation of the modules in relation to a plane, defined by the axes xz and/or
yz, as well as a variant of a mirror copy were also investigated. That is to say,
different planar DLTGs can be obtained not only by rotation, but also by the use of
mirror symmetry. Additional cables can be used in order to make the overall stiffness
of the DLTGs greater and to receive closed configurations.
2.3. Design Results
The examined planar models of DLTGs are shown in Figs. 3-5. The first one is
composed by 4x4 tensegrity units. They are without a mutual rotation. The struts of
the adjacent modules are connected to each other by end to end or only to cables. The
maximum number of rods concurring to the same joint is 3 and the minimum is 1.
Even though there are multiple possibilities to combine the Quastruts and their
variations, only two of them (Fig. 4 and Fig. 5) have the same corner zones as
geometry. When the elementary tensegrity unit derives from a cube, but it does not
completely fill the volume of the cube, this problem is an important factor in selecting
the appropriate variant. The adjacent compound elements of the second example (Fig.
4) are mutually rotated at an angle of 180˚ relative to xz plane or mutually rotated at

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an angle of 180˚ relative to yz plane plus additional rotation of 180˚ relative to xy

plane. The third model, that is shown in Fig. 5, consists of mirror copies of tensegrity
modules. The second and the third variant are composed by 4x3 tensegrity units in
order to obtain uniform corner zones as geometry. The DLTG that is shown in Figs. 4
has a maximum number of rods concurring to the same joint 3 and a minimum 1. For
the third model these values are respectively 4 and 1. According to Skelton et al. [6]
classification of any tensegrity structure can be done depending on its class k
(maximum number of struts concurring to the same joint). So while types 1 and 3 are
class 3, type 3 is class 4.

Figure 3 – Axonometry and top view of model 1

Figure 4 – Axonometry and top view of model 2

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Figure 5 – Axonometry and top view of model 3

3. CONCLUSION
The basic principle in the construction of DLTGs is the integration of basic
modules into more complex systems. Among tensegrity forms, they appear most
suitable as structural forms. Their compound units usually derive from geometric
objects that have a prismatic or pyramidal shape with triangular, square or pentagonal
bases. Also, there can be a twist angle between the upper and lower layers of the
tensegrity modules. The basic units of DLTGs can intersect each other or can be set
alongside one another in such a way that the contact between them can be through a
full or a partial overlap of their edges and/or vertex-to-edge connection. There are
variants with and without mutual rotation of two adjacent modules. Different planar
DLTGs can be obtained not only by rotation, but also by the use of mirror symmetry.
The struts of two adjoining modules can be connected to each other by end to end or
their contact can be avoided. When the elementary tensegrity unit derives from a
cube, but it does not completely fill the volume of the cube, the problem of achieving
a structure with the same corner zones as geometry is an important factor in selecting
the appropriate variant.
In the present paper it was proven that there are possibilities for generating
automatically different planar DLTGs composed of this new four-strut cubic module.
The spatial stability, strength and resistance to mechanical deformations of
tensegrities depend on the number and location of the compression struts, the extent
of prestressing the structure and the way in which the tensile cables connect the rigid
elements. By increasing the number of struts, the structure becomes more unstable
and deformable due to the larger number of connections between its elements.
Additional cables can be used in order to make the overall stiffness of the DLTGs
greater and to receive closed configurations.
The structural stability analysis of the proposed DLTGs should be the subject of
further research. The problem of creating surfaces of single curvature or double
curvature is also very important.

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ACKNOWLEDGEMENTS
The author gratefully acknowledges the financial support provided by the
University of structural engineering & architecture “Lyuben Karavelov” – Sofia for
participation in the conference. The presented results are part of my work on the
scientific research project entitled: „Innovative methods for creating tensegrity
structures for applications in architecture“.

REFERENCES
[1] Fuller B., Tensile-integrity Structures, US Patent No. 3,063,521, 1962.
[2] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado. Novel Technique for
Obtaining Double-Layer Tensegrity Grids. International Journal of Space
Structures, volume 27, (2012), issue 2 & 3, pp. 155-166.
[3] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado. Innovative Families of
Double-Layer Tensegrity Grids: Quastruts and Sixstruts. Journal of Structural
Engineering © ASCE, volume 139, (2013), pp. 1618-1636.
[4] Ilieva, Y. (2014). Genesis and contemporary trends in the development of
tensegrity enclosing planar grid structures. Proc., First scientific – applied
conference with international participation “Project Management in
Construction”, University of architecture, civil engineering and geodesy, Sofia,
pp. 405-411.
[5] Ilieva, Y. (2015). Planar Double-layer Tensegrity Grids Composed of
Elementary Cubic Modules. Proc., 2nd International Conference with Exhibition
S.ARCH, Environment and Architecture, RENECON International, Budva, pp.
409.1-409.8.
[6] Skelton R., R. Adhikari and W. Helton (1998). Mechanics of tensegrity beams.
Rep. No. 1998-1, Structural Systems and Control Laboratory, Univ. of
California, San Diego, CA.

[484]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Yuliya ILIEVA

APPLICATION OF THE “V PLUS V” GEOMETRICAL METHOD

TO FORM-FINDING OF NEW TENSEGRITY MODULES
Abstract: The creation of new forms and the determination of stable 3D geometrical configurations is
one of the current trends in the development of tensegrities. Scientists from different parts of the world
are working on this problem. A new geometrical form-finding method for creating tensegrity modules
was described in one of my previous papers. It was named “V plus V” manipulation. Following these
rules, a large class of tensegrity units can be designed. The invention was first related to cubic modules
and to a twisted truncated pyramid with square bases. The aim of the present paper is to apply this form-
finding method to regular hexagonal prisms. The discovered modules comprise six compression
elements. The struts can be clockwise or counterclockwise twisted.

Кey words: Tensegrity, modules, form-finding methods, “V plus V” manipulation, hexagonal prisms.

PRIMENA “V PLUS V” GEOMETRIJSKE METODE ZA

PRONALAŽENJE FORMI NOVIH TENSEGRITI MODULA
Rezime: Kreiranje novih form ii određivanje stabilne 3D konfiguracije predstavlja jedan od aktuelnih
trendova u razvoju tensegriti konstrukcija. Naučnici iz raznih delova sveta se bave ovim problemom.
Nova geometrijska metoda pronalaženja formi za kreiranje tensegriti modula je opisana u jednom od
mojih pređašnjih radova. Metoda je nazvana “V plus V” manipulacija. Koristeći ova pravila, moguće je
kreirati tensegriti jedinice visoke klase. Pronalazak se prvenstveno odnosio na kubne module i na
uvrnutu zarubljenu piramidu sa kvadratnom osnovom. Cilj rada je primena ove metode na pravilne
heksagonalne prizme. Otkriveni moduli obuhvataju šest pritisnih elemenata. Podupirači mogu biti
uvrnuti u smeru kazaljke na satu ili suprotno.

Ključne reči: Tensegriti, moduli, metoda pronalaženja formi, “V plus V” manipulacija, heksagonalne
prizme.

Chief Assist. Prof. Dr. Arch., University of Structural Engineering & Architecture “Luben Karavelov”, 175
Suhodolska Str., 1373, Sofia, Bulgaria, yuliya_ilieva@vsu.bg

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1. INTRODUCTION
Tensegrity structures are lightweight spatial reticulated structures, composed of
cables in tension and struts in compression. They can be defined as a subclass of
cable structures, but unlike the latter their tensile forces are not anchored. The
stability and stiffness of tensegrity structures are ensured by a self-equilibrated and
self-stress state among tension and compression members. A specific feature of these
systems is that their struts do not touch each other and do not transfer each other the
forces which they are subject to. Tensegrity structures emerged in the twentieth
century. Buckminster Fuller, David Emmerich and Kenneth Snelson are considered as
their creators. The term “tensegrity” reveals the mechanical behaviour of this type of
structures as it derives from the words tension and integrity. The American architect
and engineer Buckminster Fuller proposed it [2].
Nowadays tensegrity structures have been taken into account with increasing
frequency for the construction of canopies, roofs, covers, bridges, furniture, interior
elements and etc. They have potential for further improvement in architectural and
technical aspect. The creation of new forms and the determination of stable 3D
geometrical configurations are one of the current trends in the development of
tensegrities. Scientists from different parts of the world are working on this problem.
A new geometrical form-finding method for creating tensegrity modules was
found by Ilieva [7]. It was named “V plus V” manipulation. Following these rules, a
large class of tensegrity units can be designed. They have similar characteristics in
terms of geometry and topology. The invention was first related to cubic modules and
to a twisted truncated pyramid with square bases. The aim of the present paper is to
apply this form-finding method to regular hexagonal prisms. The discovered modules
comprise six compression elements. The struts can be clockwise or counterclockwise
twisted.

2. EXISTING EXAMPLES OF TENSEGRITY MODULES DERIVED FROM

REGULAR HEXAGONAL PRISMS
The existing examples of tensegrity modules derived from regular hexagonal
prisms were reviewed below.
In their patents Fuller, Emmerich, Snelson, Wemyss and Liapi described identical
tensegrity units composed of three rods, which were spirally twisted in a vertical
direction, and a network of connecting cables [6]. In compliance with the above-
mentioned manner of spatial arrangement, groups of similar tensegrity modules could
be obtained by increasing the number of compression struts - four, five, six and so on.
The basic units can be related to geometric bodies as a straight n-angle prism, an
oblique prism, a twisted prism and a n-angle truncated pyramid. Some of the
elementary modules that were discovered by Emmerich [1] are shown in Fig. 1. The

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double-layer tensegrity grid (DLTG) represented in Fig. 1 c is composed of basic

units which derive from regular hexagonal twisted truncated pyramids.

a) b) c)
Figure 1 – Emmerich’s tensegrity structures:a) three-strut module; b) four-strut module; c)
double-layer tensegrity grid (DLTG)composed of basic units related to regular hexagonal
twisted truncated pyramids

Gomez et al. [4] proposed a new technique, known as Rot-Umbela manipulation.

It permits conventional double-layer grids (DLG) to be transformed into tensegrity
grids. Thus opening and endless catalogue of new and unknown forms could be
obtained. In the case of a grid or tessellation, Rot-Umbela manipulation is defined as
a particular Umbela manipulation [3] in which the vertex of a grid is converted to
several nodes linked together and usually rotated around the original vertex. Final
shape and rotation are defined by the initial conditions imposed to geometry and state
of self-stress applied to the structure. Gomez et al.’s tensegrity modules derive from
different prisms whose bases have an even number of sides, that is, cubes, hexagons,
octagons, and decagons. The new structures were named respectively as the Quastrut,
Sixstrut, Octastrut, Decastrut and so forth. The Sixstrut model is shown in Fig. 2. The
topology and geometry of the basic units, and especially the connections of the bars
inside the prism, are of particular interest. The struts go from a vertex of an edge of
one base of the prism (e.g., bottom layer) to the midpoint of an adjacent edge of the
other base of the prim (e.g., top layer).

a) b) c)
Figure 2 – Gomez et al.’s Sixstrut:a) prototype built with wooden dowels and elastic stripes;
b) axonometry; c) plan view

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3. GENERATION BY “V PLUS V” MANIPULATION

3.1. “V plus V” Manipulation
The new geometrical form-finding method for creating tensegrity modules that
was named “V plus V” manipulation could be used for any convex polyhedra. The
generated elementary units comprise at least 2n compression elements. If we look at
the plan view of the basic module we will see that there are n pairs of bars. The struts
seem like intersecting letters “V” and are twisted clockwise or counterclockwise in a
vertical direction. In space compression elements pass each other between the upper
and lower layers of the body. Thus the created basic modules comply with the
definition given by Fuller [2] for tensegrity. They consist of discontinuous
compressive members and continuous tensile members. The number of rods that meet
at the same node is equal to 1. The tensegrity cells may have a certain rotational
symmetry depending on the location of their elements.
3.2. Design Results
In this part of the research the design results after the application of the “V plus V”
Manipulation to regular hexagonal prisms can be seen. Three variants of tensegrity
modules were created (Fig. 3, 5 and 6). Each of them comprises six struts. This fact
gives us reason to call the elementary units Sixstruts. The term was first introduced
for tensegrities by Gomez et al. [5]. The generated tensegrity modules have two
layers, a lower and an upper, that consist of cables. Both layers are connected together
by an intermediate layer of compression struts and tension wires, arranged diagonally.
There is no twist angle between the upper and lower sides of the hexagonal prisms
that simplifies the implementation of the basic units. The obtained modules could be
implemented for the design of DLTGs, but also for another kind of structures, like
pedestrian bridges or light canopies.
If we look at the plan view of the elementary units (Fig. 3 c, 5 b and 6 b) we will
see that there are three pairs of bars (marked with red, blue and brown). They seem
like three intersecting letters “V” and are twisted in a vertical direction. Each
compression strut connects a vertex of one of the bases of the hexagonal prism (i. e.
the bottom) to the midpoint of another edge of the other layer. For the Sixstrut
module 1 this is the opposite edge of the other base. The bottom tips of the three “V”
letters do not match. In plan view they are situated on every other edge of the
hexagon. The opening angle of letter “V” for the modules is respectively 32.2˚,
33.0˚and 98.2˚. The top and bottom cables of the modules outline a six-sided shape.
There are no additional diagonal tensile elements at both of the bases of the
hexagonal prisms. So the number of the cables of each base of the elementary units is
equal to 6. The number of the diagonal cables of the tensegrity modules is equal to 9.
They extend from each of the nodes of a layer (i. e. the bottom) that reaches a
compression element to the corresponding node corner of the other layer (i. e. the top)
and vice versa. Additionally, I tried to get new variations of tensegriy modules that
have the same configuration of rods, but different distribution of wires at the bases
(Fig. 3 and 4). The embodiment shown in Fig. 4 has 6 diagonal cables instead of 9. Its

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spatial stability is deteriorated in comparison with the variant represented in Fig. 3.

Additional cables in the boundary of the prisms can be used in order to make the
overall stiffness greater. The generated Sixstruts have a rotational symmetry of 120˚.
Their alignment is not the same, which gives more versatility to the design of
different types of DLTGs.

a) b) c)
Figure 3 – Sixstrut module 1: a) architectural model; b) axonometry; c) top view

a) b) c)
Figure 4 – Another embodiment of Sixstrut module 1: a) architectural model; b) axonometry;
c) top view

a) b)
Figure 5 – Sixstrut module 2: a) axonometry; b) top view

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a) b)
Figure 6 – Sixstrut module 3: a) axonometry; b) top view

4. CONCLUSION
In the current paper the existing examples of tensegrity modules derived from
regular hexagonal prisms were reviewed. It was proven that the new geometrical
form-finding method named “V plus V” manipulation may be used for the generation
of different double layer tensegrity modules. In this research they were related to
regular hexagonal prisms. With the increase in the number of struts of this kind of
structures, they become more unstable, because of the higher number of connections
in the system. Additional cables in the boundary of the prisms can be used in order to
make the overall stiffness greater. The possibilities for creating innovative units are
open. The application of the invention to other convex polyhedra should be the
subject of further research. Structural stability, rigidity, resistance, and deformation
analysis of the proposed modules also has to be done. The combination of these new
tensegrity units for the generation of new DLTGs should be examined too. It depends
on their different variations, ways of composition and methods for stiffening them.

ACKNOWLEDGEMENTS
The author gratefully acknowledges the financial support provided by the
University of structural engineering & architecture “Lyuben Karavelov” – Sofia for
participation in the conference. The presented results are part of my work on the
scientific research project entitled: „Innovative methods for creating tensegrity
structures for applications in architecture“.

REFERENCES
[1] Emmerich, D. (1964). Construction de Reseaux Autotendants, French Patent No.
1.377.290.
[2] Fuller, B. (1962). Tensile-integrity Structures. US Patent No. 3,063,521.
[3] Gancedo Lamadrid E., J. Gómez, J. González and J. Menéndez (2004). A New
Method to Obtain and Define Regular Polyhedra. Geometriae Dedicata, 106 (1),
pp. 43–49.

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[4] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado (2012). Novel

Technique for Obtaining Double-Layer Tensegrity Grids. International Journal
of Space Structures, volume 27, issue 2 & 3, pp. 155-166.
[5] Gómez-Jáuregui V., C. Otero, R. Arias and C. Manchado (2013). Innovative
Families of Double-Layer Tensegrity Grids: Quastruts and Sixstruts. Journal of
Structural Engineering © ASCE, volume 139, pp. 1618-1636.
[6] Ilieva, Y. (2014). Innovative Solutions for Designing Tensegrity Structures.
Proc., International Conference on Civil Engineering Design and Construction
(Science and Practice), Varna Free University “Chernorizets Hrabar”, Varma,
pp. 394-401.
[7] Ilieva, Y. (2015). New Geometrical Form-finding Method for Creating
Tensegrity Modules. Proc., 13th International Scientific Conference iNDiS 2015,
Planning, desing, construction and building renewal, University of Novi Sad,
Novi Sad (in print)

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Ljiljana JEVREMOVIC
Branko AJ. TURNSEK2
Milanka VASIC3
Marina JORDANOVIC4

INCREASING CAPACITY TO REDEVELOP INDUSTRIAL

BROWNFIELDS THROUGH URBAN HERITAGE PROMOTION
Abstract: Understanding historical value and significance of inherited industrial landscapes that are
unused and abandoned due to numerous reasons may help us to find more appropriate forms of their
conversion. By evaluating the urban morphology of the particular site, and knowing and learning about
the urban structure, their relations and processes of transformation, the aim was to create a framework
that can be used in regeneration processes. The outcome of the analysis was in the text discussed in the
context of integrating this principle with the on-going practice of brownfields redevelopment. The
discussion is devoted to the improvement of the existing theory and practice of industrial brownfields
redevelopment by highlighting the main pros and cons of the proposed strategy.

Кey words: industrial brownfields, urban morphology, redevelopment, urban heritage, planning.

UNAPREĐENJE KAPACITETA ZA OBNOVU INDUSTRIJSKIH

BRAUNFILDA KROZ PROMOCIJU URBANOG NASLEĐA
Rezime: Razumevanje istorijske vrednosti i značaja nasleđenih industrijskih prostora koju su danas
neupotrebljeni i napušteni kao posledica brojnih razloga, može nam pomoći da pronađemo odgovarajuće
mogućnosti da se takvi objekti i prostori konvertuju. Evaluacijom urbano morfologije konkretnih
lokacija, proučavanjem njihove urbane strukture, njehovih relacija i procea rtensformacije, naš cilj je da
se stvori okvir koji se može daje koristiti u procesima regeneracije. Rezultati ovih analiza u radu su
diskutovani u smislu njihove integracije u postojeći okvir obnove industrijskih braunfilda. Diskusija je
posvećena i unapređenju postojeće teorije i prakse u obnovi indstrijskih braunfilda uz isticanje glavnih
prednosti i mana predložene strategije.

Ključne reči: industrijski braunfild, urbana morfologija, obnova, urbano nasleđe, planiranje.

1
PhD Student, Faculty of C. Engineering and Architecture, A.Medvedeva 14, Nis, jevremovicljiljana@gmail.com
2
PhD, Associate Prof., Faculty of C. Engineering and Architecture, A.Medvedeva 14, Nis, ajbranko@yahoo.com
3
PhD Student, Faculty of C. Engineering and Architecture, A.Medvedeva 14, Nis, milanka.vasic@gaf.ni.ac.rs
4
PhD Student, Faculty of C. Engineering and Architecture, A.Medvedeva 14, Nis, marinajordanovic@gmail.com

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1. INTRODUCTION
For the last several decades, industry has been vanishing from the cities and their
core urban areas. Although the reasons are greatly different, the decay of industry has
brought the similar problems and processes to many of the cities worldwide. The
derelict land and dilapidated buildings that are left abandoned, challenge architects,
planners, politicians and all those who are interested in the vitality of own cities.
Today, there is decades-worth of achievements ranging from well-publicized projects
to those only known by their neighbors. As the schemes of the redevelopment
strategies are usually very different, but in the same time they are mainly focused to
economic beneficiaries, we are proposing here recognition and evaluation of heritage
value of brownfields sites that may open up new solutions to planning, policy and
design problems that are common to regeneration projects. Understanding historical
value and significance of inherited industrial landscapes that are left unused and
abandoned due to numerous reasons may help us to find more appropriate forms of
conversion. The discussion is devoted to the principle of improving the existing
theory and practice of industrial brownfields redevelopment by highlighting the main
pros and cons of the proposed strategy.
Knowing that there are much more important aspects that significantly shape the
redevelopment strategies and projects, here is more concerns given to an idea that in
societies that have not jet faced any of successfully redevelopment, such as Serbia is,
is very important for a start to emphasize the existence of urban heritage. In some
way, it would be necessary to educate the society, not only professionals, to
recognize, respect and to value own urban heritage. [6]
The paper deals with brownfield are defined as areas that have lost their previous
function and as such represent a negative phenomenon in cities. The principal idea of
the paper is to demonstrate the potential that lies in brownfield. Emphasis is placed on
the urban morphology of brownfield areas with particular emphasis on the
morphology of modernist complexes, which were characteristic to the industry almost
the entire twentieth century. This approach to the problem of brownfields is important
because it can contribute to a better understanding of the potential that lies in
industrial brownfields and to display them in a different light in terms of promoting
their capacities. For all of the negatives that accompany them, a different "reading" of
such spaces acts as a positive impulse. To understand this idea, it is necessary to point
out that there is a quality of modernist urban space of industrial complexes that can be
pointed out as comparative advantages of spaces that need revitalization.

2. A SHORT HISTORY OF URBAN HERITAGE THEORY

By definition given in Habitat III Issue Paper „Urban heritage represents a social,
cultural and economic asset and resource reflecting the dynamic historical layering of
values that have been developed, ... . Urban heritage comprises urban elements (urban
morphology and built form, open and green spaces, urban infrastructure),
architectural elements (monuments, buildings) and intangible elements. Urban

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heritage conservation or urban conservation relates to urban planning processes

aimed at preserving cultural values, assets and resources through conserving the
integrity and authenticity of urban heritage, while safeguarding intangible cultural
assets through a participatory approach.“ [1]
Such approach in polices of planning and developing cities is not a recent agenda.
Already during the nineteenth century there were some hints towards a wider scope of
looking at the meaning and management of heritage. John Ruskin, pioneer in the
protection of historic monuments who has been influential at an international level
when it comes to heritage protection, noted the importance of a wider scope in
heritage protection by introducing the possibility of attributing value to more than just
the „isolated richness of palaces“. He did not identify the value of the whole, but
made a start by identifying the value of more than just some specific palaces. For
Ruskin, urban fabric consists of varied assemblies, in which all buildings could be
preserved. While Ruskin argues for the conservation of the individual elements that
convey memorial and social values, Camilo Sitte mostly argues their sum in historic
and esthetical values. Sitte is considered to be the first of a generation of urban
morphologists who really focused on the existing city and its essential (tangible)
elements. He provided us with a new objective in urban planning: the preservation of
urban structure and fabric. Later, Patrick Geddes claimed that „urban heritage
underpins urban development“, but actually Gustavo Giovannoni is credited with the
invention of the actual term ‘urban heritage’; he argued and promoted the protection
of heritage on an urban scale, without excluding the importance of urban development
as he defined a historic city as a monument and a living fabric at the same time. [3]

3. ANALYSIS OF BROWNFILED SITES – TWO EXAMPLES

In order to simplify the presentation of ideas that are promoted in the text, this
article analyzes the two industrial complexes in Serbia through whose analysis it is
possible to consider the factors that may be relevant to a potential renewal.
Intentionally the chosen examples of two typologically and morphologically different
complex that will as such be compared. There are several aspects that can be
compared and analyzed in this comparative process:
 typology of the urban form of the block and complex,
 typology of buildings - architectural materialization and style,
 treatment of open areas and their capacity,
 evaluating social acceptance of the brownfield.
As neither of these two industrial-complex has not been revitalized, cannot be
measured by their degree of success of any search for potential success factors, but
our analysis will be focused on the exploration potential that lies in them. A
comparative analysis of the two in many ways different complexes want to stress that
their particularities i.e. the specificity of the group they represent.

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3.1. Old Weifert's brewery, Pancevo

Old Weifert’s brewery is an industrial complex in the center of Pancevo, which
was built in the period from the end of XVII century to the 30's of XX c. Architecture
belongs to the epoch in which it was built and by the function, unlike today, the
brewery served as a self-contained complex for the production of beer but also as a
place for a gustation (a pub), as well as a sort of meeting place of important social
events in the city. The building was out of order last few decades, while the process
of its devastation starts since the end of World War II.
The form of the urban block of this complex features as a closed block with edge
construction of buildings with inner courtyards. The building in the complex have
different levels from ground to those with two or more floors. The complex was built
in stages, and upgraded without homogeneous approach to the design and
materialization of objects. However, the main characteristic of all objects are massive
brick walls, mainly plastered and painted. Some objects have richly decorated the
fronts facing the street, especially towards the main (now pedestrian) street where is
positioned the main entrance to the complex. Also, the form and composition of the
complex is closed so that except the entrances, there are no many openings towards
the surrounding streets. The buildings are organized facing the internal courtyard.
This area is not very large due to the development of the complex through decades
and building the complex on the limited space, the open free space is reduced to a
minimum. In fact, the planned green space is almost gone, and open surface is paved
with stone blocks.

Figure 1 – Site plan Old Weifert Brewery Pancevo (SERBIA)

Today, the entire complex is recognized as a treasure trove of history of industrial

architecture of the region and is as valued as a significant cultural and historical

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monument protected by the authorized departments’ acts that do not allow any change
of existing facilities except revitalization. However, these acts failed to prevent an
absolute decline of the complex due to lack of maintenance, neglect and complete
abandonment. It is so rundown, with no real function for more than 40 years, that the
rich architectonics of space, the spirit of place and atmosphere completely faded and
the identity of this complex that had gave almost to the whole city (depot building
was an essential part of many postcard of Pancevo for years) is fading away. Formal
recognition of the status of this complex as a cultural property is absolutely positive
signal, but the inertness in realization has the rehabilitation plans transformed into
their contradiction.

Figure 2- Old Weifert Brewery Pancevo (SERBIA)

3.2. Electronic Industry, EI Nis

Electronic Industry site in Nis, with area of 66ha, 4.5.km from city center, once
had been outskirt of the city. Today this area is positioned deeply in the matrix of
urban area of city of Nis. This complex has been built after the WWII, while in last
two decades it has lost all of its earlier functions. Well equipped with infrastructure,
with good traffic connections, which gives advantage, this complex is recognized
with a chance for successful redevelopment. Built as modernistic complex, with
spatial patterns that are recognized with freestanding buildings and a lot of free open
spaces with greenery that are orthogonally shaped with matrix of internal traffic
roads. This is important advantage giving possibilities to divide the site into separated
plots with satisfying communications of each plot, which would reduce
redevelopment costs in advance. Complex of 20 buildings on the site is mainly made
of production buildings. The site was built and developed during a period of several
decades, so that buildings differ by age, in appearance, vary by degree of
preservation, and have different level of architectural attractiveness and usefulness.
However, the site as a whole as well as the buildings within the complex is not listed
as a protected heritage and could be significantly changed or even destroyed during
the redevelopment process.

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Figure 3 – Site plan Electronic Industry Nis (SERBIA)

A previous production of electronic appliances undoubtedly has left consequences

considering soil contamination, which has to be determined. However, despite all
today this complex serves as a kind of business park, since many small companies
find some of the buildings in the complex suitable for their business. By renting free
and abandoned industrial facilities for new business this complex begun a new life
cycle that has spontaneously raised on the fragments of the old one. Although this is
very positive impulse, the lack of strategy and a systematic approach, this
spontaneous growth has also brought additional destruction of the original complex,
as well as inappropriate alterations of the buildings and the complex as a whole.

Figure 4 – EI Electronic Industry Nis (SERBIA)

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4. CONCLUSIONS
By comparison of these two examples, it is possible to conclude that, regardless of
the differences in position, shape and dimensions, both these former industrial
complexes have developmental problems. The variety of eras that belong to, make a
difference in the architectural style as well as in urban form and typology of
complexes. This difference is especially featured when compared to treatment with
the complex in terms of protection as architectural heritage. While this older
(brewery) is protected as a cultural and historical property, this postwar soc-realistic
complex (electronic industry) is not identified as such. The compact structure of the
non-uniform complex of brewery gives picturesque look of old structure that can be
put to good use. The size of buildings, their proportions and worthy materialization
are also the positive side of the brewery complex. On the other hand, oversized as a
whole, and out of proportion to the humane size, complex of electronic industry
seems to require a complex reflection on new functions. Yet the size of the free space
in the complex as well as the dimensions of buildings that are not burdened by the
demands of heritage protection of cultural values, have led to certain economic
activities within the complex. Especially here should be emphasized the possibility of
separating it into many smaller units which operate apart. Also, the greenery that
surrounds the buildings specifically enriches the space, and can be considered an
important factor in the evaluation environment that exists within the industrial
complex. Despite the low architectural value of buildings, their changeability and
freestanding position in the space, enough green lawns in the environment as well as
easy accessibility to the city traffic roads are main strengths of such complexes. On
the other hand, older complexes are usually recognizable and socially significant but
such references can be burdensome factor for them. Also a site that is actually
historical city core, while on the one hand means the potential of the other is the limit.
The redevelopment projects of underused and abandoned industrial areas should
follow design principles that promote sustainability, reduce negative environmental
impacts, and foment economic prosperity, social inclusion, multi-functionality and
better quality of life. For this reason such projects should reinforce the character of
the existing urban structure taking into consideration the spirit of the place and
integrating the previous existence (industrial) in the new multifunctional landscape, in
order to achieve sustainable development, not only environmentally, but also
culturally, socially and economically. After the analyses in this article it is concluded
that in Serbia the post-industrial landscape is commonly experienced negatively as
fragmented and incoherent because it is difficult to conceive a legible whole. The
sites presented constitute representative examples of post-industrial landscape which
reclamation in Serbia would enable a sense of spatial enrichment, with high degree of
complexity, richness in historic layers of spatial and urban structure and with diverse
economic, ecological and social benefits. [2]
There are many lessons to be learned about how cities are changing from hubs of
industry to redefined urban centers. While it’s obvious that works for one doesn’t
work for all, certain principles crop up throughout many of the projects. Whether is

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about the remarking of a harbor or the rebuilding of dilapidated building, the

redevelopment of industrial sites required incredible perseverance, knowledge, and,
yes, a bit of luck. [6]

REFERENCES
[1] The United Nations Task Team on Habitat III 2015. Habitat III Issue Papers, 4 –
Urban Culture and Heritage. New York: UNESCO.
[2] Panagopoulos, Thomas 2009. From Industrial to postindustrial landscapes –
brownfield regeneration in shrinking cities. Proceedings of the 2nd WSEAS
International Conference on Urban Planning and Transportation (ISSN: 1790-
2769, ISBN: 978-960-474-102-1): p.p.51-57.
[3] Veldpaus, Loes; Pereira Roders, Ana R.; Colenbrander, Bernard J. F. 2013.
Urban Heritage: Putting the Past into the Future. The Historic Environment, Vol.
4 No. 1, W. S. Maney & Son Ltd: p.p. 3-18
[4] Solitarea, Laura; Lowrie, Karen 2012. Increasing the capacity of community
development corporations for brownfield redevelopment: an inside-out approach,
Local Environment, Vol. 17, No. 4, Taylor & Francis: p.p.461–479
[5] Jevremovic Ljiljana, Turnsek A.J. Branko 2014. A Role of Brownfields in
Strategic Planning – Understanding Potential, BROWNINFO - International
Academic Conference, 6-7 November 2014, University of Banja Luka Faculty of
Architecture, Civil Engineering and Geodesy, Conference Proceedings, eds.
Djukic A., Stankovic M., Milojevic B., Novakovic N., p.p. 55-63, Banja Luka,
Bosnia & Herzegovina
[6] Jevremovic, Ljiljana; Vasic, Milanka; Jordanovic, Marina 2012. Aesthetics of
Industrial Architecture in the Context of Industrial Buildings Conversion, IV
International Symposium for Students of Doctoral Studies in the Fields of Civil
Engineering, Architecture And Environmental Protection – PHIDAC, Faculty of
Civil Engineering and Architecture, Nis, Serbia, 27-28 September 2012,
Proceedings (ed. Z. Grdic, G. Toplicic-Curcic), p.p. 80-87
[7] Jevremovic, Ljiljana; Turnsek, Branko AJ. 2011. Possibilities of Brownfield
Sites as Land Resource for Sustainable Urban Development and Space
Management, The 4th International Conference on Hazards and Modern Heritage
- „The Importance of Place“, 13.-16. June 2011, Sarajevo, B&H, Proceedings
Vol. 1, No. 1, p.p. 416-428, CICOPBH, Sarajevo, B&H
[8] Jevremovic, Ljiljana; Turnsek, Branko AJ. 2009. Contribution to Analysis of the
Problem of the Reintegration Desolated Industrial Complexes in Urban City
Structure, 11th National and 5th International scientific meeting - iNDiS 2009 –
Planning, design, construction and renewal in the civil engineering, 25.-27.
November 2009, Novi Sad, Proceedings, p.p. 225-237, Novi Sad

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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Milena KRKLJEŠ
Dijana BRKLJAĈ2
Stefan ŠKORIĆ3
Aleksandra MILINKOVIĆ4

CHILDREN'S SPATIAL PERCEPTION - DESIGN OF

PLAYGROUNDS
Abstract: Spatial perception is a process, very important for many functions in children’s development.
Perception gives the child the ability to establish the relationship with space as well as with various
objects in public space. It is therefore necessary for successful use of the equipment on playgrounds.
When using all elements and equipment children coordinate their physical movements in relationship to
what is perceived in the space. Most of playground’s design is focused on “safety”, neglecting the
importance of children’s perception. Therefore the aim of this paper is to discuss what playgrounds for
children should be like, having in mind design suggestions that have implemented design principles
starting from contemporary observations about children’s spatial perception.

Кey words: spatial perception, children, playgrounds, design, public space.

PROSTORNA PERCEPCIJA DECE – DIZAJN DEČJIH IGRALIŠTA

Rezime: Prostorna percepcija je process koji je veoma važan za mnoge funkcije u razvoju dece, jer im
omogućava uspostavljanje interakcije sa okruženjem u celini, kao i sa svakim pojedinaĉnim elementom
ili objektom koji ga ĉini. Stoga ima znaĉajnu ulogu u svakodnevnoj igri dece. Kroz korišćenje razliĉite
opreme na igralištima, deca koordiniraju svoje fiziĉke pokrete u odnosu na ono što opažaju u prostoru.
Dizajn igrališta se pretežno fokusira na bezbednost, zanemarujući znaĉaj deĉje percepcije. Cilj ovog
rada je istraživanje o kvalitetu igrališta, imajući u vidu dizajn strategije koje sprovode principe dizajna
bazirajući se na savremenim zapažanjima o deĉjoj prostornoj percepciji.

Ključne reči: prostorna percepcija, deca , igrališta, dizajn, javni prostor.

1
PhD., assistant professor, University of Novi Sad, Faculty of Technical Sciences, Trg Dositeja Obradovića 6, Novi
Sad, Serbia, 021 485 2462, milenakrkljes@gmail.com
2
MArch., teaching assistant, University of Novi Sad, Faculty of Technical Sciences, dijana.apostolovic@gmail.com
3
MArch., research assistant, University of Novi Sad, Faculty of Technical Sciences, skoricstefan@yahoo.com
4
MArch., teaching assistant, University of Novi Sad, Faculty of Technical Sciences, aleksandrabandic@gmail.com

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1. INTRUDUCTION
The most important activity during child development is play, the behaviour that
provides children with possibilities to explore, interact with and learn about their
environments. According to many scientists play is significant in all phases of child’s
life. Friedrich Froebel, inventor of the kindergarten, states that play is highly serious
and of deep significance [4], and like Vygotski observed it has developmental
tendencies and is itself a major source of development [11]. According to Frost, play
is the primary means of development of imagination, intelligence, language, and
perceptual-motor abilities in infants and young children [6].
Starting from the fact that play is important for the development of children’s
social, emotional, cognitive and physical ability, as well as creativity and imagination,
design of places that are meant as playgrounds have mediating role in the overall
developing process. Recently, most of playground’s design is focused on safety,
neglecting the importance of other issues that should be implemented in overall
design, such as the question of children’s perception. Perception is the ability to
interpret and understand the information that comes through the senses as a response
to the environment, a dynamic process that identifies, organizes, interprets, and
understands what is perceived. It integrates sensory and motor information generated
by the brain and body to derive meaning from it and direct movement. Therefore the
aim of this paper is to discuss what public playgrounds for young children should be
like, having in mind those design suggestions that have implemented design
principles starting from contemporary observations about children’s perception.

2. CHILDREN’S PLAY AND SPACIAL PERCEPTION

Spatial perception is a developing process, very important for many functions in
children’s development. It is the ability to interpret and understand what is seen,
developed by integrating and using the information gathered, learning from it and
modifying the information by experience. Perception gives the child the ability to
establish the relationship with space as well as with various objects in public spaces.
This mostly incorporates sight with the interpretation of the physical environment, but
should also incorporate their understanding of what is seen and how it should be used.
It is therefore necessary for successful use of the equipment on playgrounds. Through
using all elements and equipment children coordinate their physical movements in
relationship to what is firstly perceived in the space.
Spatial perception has influence on children's behaviours on playgrounds. It is
shown that there are differences in children's behaviours on various playgrounds, not
strictly according to the extent to which they reflected contemporary design
suggestions, but more in special organization such as zoning, encapsulation and the
provision of appropriate materials, that are connected with the way children perceive
the space on which the play should be organized [1]. The researchers have shown that
visual perception is a required skill on the playground for successfully using much of
the playground equipment. It is specially important when using overhead equipment,

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such as overhead ladders, rings, and monkey bars, when children must judge the
distance from one rung to the next and then coordinate their physical movements to
reach the next rung [7].
For understanding the importance of special design of playgrounds related to the
children’s perception it is important to have in mind different categories of play.
According to Brown et alt. the first category is "cognitive play" which primarily build
thinking and reasoning skills and includes repetitive muscle movements to explore the
environment (e.g., repeatedly hitting the ground with a shovel, or repetitively going
up and down the steps), exploratory play, pretend play, construction play (e.g.,
building sand castles), and games with rules. The second category is "social play" that
encapsulates the various ways children interact with peers. The third category deals
with children's physical development and includes physical growth of the body and
vital organs, health-related fitness, gross and fine motor activities. A fourth category
deals with children's emotional development, which includes affective reactions
during play, including behaviours such as aggression and verbal signals [2].
According to Frost et al., perceptual-motor skills include body awareness
(understanding about the different parts of the body, how they move, what they can
do and how to make movements more efficient), spatial awareness (understanding
about how the body and objects occupy space and how to move them within that
space), directional awareness (understanding about the location and direction of the
body and objects in space) and temporal awareness (understanding about the
relationship between movement and time) [5].
There are also many health-related benefits, such as muscular endurance, strength,
flexibility that might be improved through play in all types of movement [9],
experience, including both gross and fine motor activities, increases muscular
responses by strengthening synaptic connections [8] and therefore playgrounds could
be places whose proper design and appropriate equipment might stimulate and force
children’s overall development.

3. INTERDEPENDENCE OF PERCEPTION AND PLAYGROUNDS

DESIGN
Since perceptual-motor development results from the interaction between sensory
perception and motor actions in increasingly complex and skilful behaviours [5], four
above-mentioned categories of play cover the spectrum of behaviours children engage
in during the play and give adults guidelines how to design environments of children's
play. Urban designers and architects must have an important role in this process,
trying not to use only prefabricated equipment, but to improve knowledge about
children play and perception in the holistic design of the play environment.
The important issue in design of playgrounds is how to implement knowledge
about perception to design contemporary playgrounds that will promote educationally
desirable social, language, or motor behaviours as well as simple and free play.
Recently, playground design was too focused much more on safety, based on the

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socially accepted myth that playgrounds are dangerous [7], but on research how
children really perceive their playgrounds. Although safety is important issue, much
more important one is to create natural, challenging places for children to play
spontaneously.
Perception is very important for children’s play on playgrounds, since it guides
motor activities and interprets space and time. From one side it is important as basic
point for design of various elements for play, but on the other one it is a learned skill
and developed over time, and therefore all equipment and its design have influences
on child development. The ability to interpret and understand what is seen is
developed by integrating and using the information gathered, learning from it, and
modifying the information by experience. Since children spend most of their time
playing, it is very important to have in mind those influences during design of
equipment end environment for their play.
It is important to have in mind some of the points related with the perception of
the space, that are defined in the research about specific activities on the playgrounds,
to see why they are important and how they help children to perceive the environment
around them. The first one is climbing, the activity through children increase their
visual field, perceive closer the nature, experience basic physics (gravity, inertia,
pendulums, optics), stimulate kinaesthetic perceptions and increase vestibular
sensations. There are also perceptual motor skills developed while climbing, such as
body awareness, spatial awareness and directional awareness and as well as visual
perception skills since while climbing, children develop the ability to perceive
affordances. There are also some benefits of play on overhead equipment, such as
developed visual perception of distance and spatial coordination. Although swinging
has not been directly connected with the spatial perception, it improved cognitive
development and sensory stimulation that are related with the visual perception.
Besides playing on the elements on playground, sand and water play is mostly closed
to the natural play and therefore have some benefits that are related with sensory
exploration [7].

Figure 1 – Playgrounds with various elements of perception

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Considering possible ways for designing children’s playgrounds, it is important to

bear in mind that the perception and needs of children considerably differ from those
of adults. From children’s perspective, space can be defined as a serious of different
structural elements whose relations forms an entity. Spaces for children should not be
something definite and final, but in continuous process of transformation and places
of open possibilities that would encourage their development [10]. Besides following
of the standards, designers should have in considerations aspects of proper children
psychophysical and social development. Since children recognize space as a series of
activities connected with a particular place, we should consider that during designing
playground to provide them with environment that consists of everyday challenges
suitable for their levels of development, age and gender, encouragin them to explore
and discover new possibilities of their own surroundings. Also, every single element
that is used in playgrounds should have challenging role in children's play and not be
just the standard and boring one. More greenery on the site can make play pleasant
during the hot summer days and also provide cosy environment. In addition, some
urban furniture and lighting may contribute to a better image of these spaces and also
to a better safety perception.

4. CONCLUSION
If we accept facts that perceptions and needs of children considerably differ from
those of adults and that children need freedom to create their own games, we have to
offer them inspiring places of playgrounds, but at the same time, they must be safe
and designed according to the highest predefined safety standards in line with most of
the recommendations for overall sustainable development. We should have in mind
that play involves the whole child and that thinking, creative expression of thoughts
and feelings, and physical demands all interact in the dynamic process of play [3].
Therefore they perceive spaces and develop experiences through their senses,
movements through spaces, creating their own world of existence. They are
constantly learning and developing through continuous play and perception of
environments around them. All of playgrounds should be designed as child-friendly
environments that promote exploration and environmental learning, different
activities and social interactions, by adequate shaping of physical characteristics of
playgrounds and by allowing children to express themselves freely in creation and
control of their spaces. Only in this way, play-spaces can become appropriate for
overall children’s development.

ACKNOWLEDGEMENTS
The paper was done within the project “Optimization of architectural and urban
planning and design in function of sustainable development in Serbia” (TR36042),
funded by the Ministry of Education, Science and technological Development,
Republic of Serbia.

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REFERENCES
[1] Brown J. G., Burger C. (1984). Playground Designs and Preschool Children's
Behaviors. Environment and Behavior vol. 16 no. 5, pp. 599-626.
[2] Brown P.S., Sutterby J. A., Therrell J. A., Thornton C. D. The Importance of
Free Play to Children's Development, www.imaginationplayground.com
[3] Chatterjee S. (2005). Children’s Friendship with Place: A Conceptual Inquiry.
Children, Youth and Environments 15(1). pp. 1–26.
[4] Froebel, F. W. (1887). The education of man. New York: D. Appleton.
[5] Frost, J., Wortham, S. & Reifel, S. (2001). Play in child development. Columbus,
OH: Prentice Hall-Merrill.
[6] Frost, J. L. (1992). Play and playscapes. New York: Delmar Publishers.
[7] Frost, J. L., Brown P. S., Sutterby J. A., Thornton C. D. (2004). The
Developmental Benefits of Playgrounds. Olney, MD: Association for Childhood
Education International.
[8] Gabbard, C. (1998). Windows of opportunity for early brain and motor
development. Journal of Physical Education, Recreation and Dance, 69(8), pp.
54-61.
[9] Ignico, A. (1994). Early childhood physical education: Providing the
foundation. Journal of Physical Education, Recreation and Dance, 65, pp. 28-30.
[10] Krklješ M., Jevtić M. (2012). Playgrounds in Novi Sad (Serbia) and their
influences on children's health and development. HealthMED, Vol. 6, No. 3,
DRUNPP, pp. 864-874.
[11] Vygotsky, L. S. (1978). Mind in Society: The Development of Higher Mental
Processes. Cambridge, MA: Harvard University Press.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Nadja KURTOVIC FOLIC

ON AESTHETICS OF ENGINEERING STRUCTURES

Abstract: Throughout the history, people have been creating engineering structures according to the
ability of builders. This term, builders, means both, technical knowledge of construction engineers and
architects aesthetic sensibility. When in the nineteenth century came to a stark division between civil
engineer-constructors and architects, it was time when it was also open discussion on what constitutes
the aesthetic value of the engineering structures? Is it a specific, selected structural form itself that is
aesthetically very valuable or it needs to be upgraded by decorative elements to get on the better
aesthetic value? The paper will present the classic aesthetic criteria for engineering structures, with
examples. It will then point to today's practice and creation of magnificent engineering structures in
whose design the role of the architect is very specific.

Кey words: aesthetics, engineering structures, architecture, principles, criteria, values.

O ESTETICI INŽENJERSKIH KONSTRUKCIJA

Rezime: Kroz celu istoriju ljudi su stvarali inzenjerske konstrukcije u skladu sa mogucnostima graditelja.
Termin graditelj oznacavao i tehnicko znanje formiranja konstrukcija i arhitektonski estetski senzibilitet.
Kada je u XIX veku doslo do razdvajanja gradjevinskih inzenjera i arhitekata, otvorena je diskusija sta
predstavlja estetsku vrednost inzenjerske konstrukcije? Da li je to estetski vredna konstrukcija sama po
sebi ili treba da se unapredi dekorativnim elementima da bi dostogla vecu estetsku vrednost? U tekstu se
predstavljaju klasicni estetski kriterijumi za inzenjerske konstrukcije i ukazuje na savremenu praksu u
kojoj je uloga arhitekata vrlo specificna.

Ključne reči: estetika, inzenjerske konstrukcije, arhitektura, zakonitosti, kriterijumi, vrednosti.

To Radomir Folic who loves engineering structures and family

Dr, University of Novi Sad, Trg D. Obradovica 6, Novi Sad, Serbia, nfolic@gmail.com

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1. INDRODUCTION
Throughout the history of construction it was considered that the builder should be
very knowledgeable, and especially to be well versed in the design of spatial
organization, structure, materials and techniques, decorative details, finance,
organization and construction, land policy, politics in general, the human response to
the built forms, social trends, in short, to be a kind of encyclopaedists in building
jobs. This knowledge, however, only helps that he, as an artist, could express his
aesthetic conceptions. Each of these specialities he could have known more or less,
but the aesthetic values of the epoch in which he had created had to know in details.
Modern division between the structural engineer and the architect was not expressed,
only some builders know entirely how to carry out their buildings, including
construction, while others needed help of the colleagues who were more skilful to
experience with what constructive solutions will be building, bridge, or fortification,
will be more stable. Today these are not just structural engineering more inclined to
the builders, but structural engineers specialized in designing structures in which,
sometimes, the architect has a marginal role. As a result, the personality of designers
and architects are destined to clash. Mario Salvadori explains this situation writing:
"Happy is the client whose architect understands the construction and designer whose
structural engineer prices aesthetics of architecture."[21]
The study of the links between architecture and engineering is a complex issue,
because those responsibilities often overlap. Both professions are now participating in
the design of various structures. The architect should design a protective covering of
space that should meet the needs of the client, as well as aesthetic appearance. The
main responsibility of the engineer is to ensure stability and security structures in
accordance with the laws, regulations and standards. The cooperation of architects
and constructors can take place smoothly, with full understanding of the common
task. Communication, however, does not always have to be so balanced, it can consist
of mutual criticism, different requirements and restrictions. This second, more
unpleasant form of cooperation is much better documented from the moment when
the jobs are architects and civil engineers have become more clearly profiled, when
their education has become more focused on different types of training for performing
specific tasks, and when, in recent times, investors showed great interest in
extravagant, profitable projects.
From the earliest times all structures contain an element of aesthetic experience,
even if the builder does not seek to do more than just to satisfy the function. [11] It is
known that the original structure are developed by imitating natural forms, and since
the laws of nature usually constitute the starting point for the fundamental laws of
aesthetics, then the imitation of nature in shaping the structure causes their aesthetic
expression that relates to the natural environment. [16] For example, bridging the
natural barrier by building the bridges always amazes and excites users and observers.
The convincing functionality and form that surpass those of nature, with intuitive
aesthetic of engineering present the basic source of this perception, showing the

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principle which is the starting point in creating confidence in the transfer of power
and the human ability to accomplish it. This adrenaline-rich aesthetic experience was
able to realize, for example, professor Mijat Trojanovic who built the bridge on Tara
River (from 1937 to 1940.year). The bridge is 172 m above the river Tara, 365 meters
long, with five arches, the biggest range of 16 meters.

Figure 1 - Bridge on Đurđevića Tara, designed by Mijat Trojanović

(copyright@www.montenegrotravel)

2. BASIC PRINCIPLES OF AESTHETICS OF ENGINEERING

STRUCTURES
Occupied with the complex problems of form, function and construction, modern
researchers sometimes neglect aesthetics which marked their era throughout history.
[9] Often, even the lack of a width of judgment brought to a complete neglect of
certain aesthetic legality pursued in the history of art of building. However, we are
constantly talking and writing about the good and bad structures, and such division
exists in all other arts. This is because by hype, the current fashion that can be
affected, which can pander, there are universal laws that were in force for all forms,
regardless of the time of their creation. This legality extended to all arts, and to the art
of building creativity too.
The origin of those principles is complex, so they are more concerned with
philosophers and psychologists. But regardless of where they are based, certain laws
follow all the creative arts. These are the general rules according to which the human
mind always works when strives to create something, or to produce something that
will have as a goal the creation of quality beauty that satisfies human needs and
feelings.
First of legality is so universal and so essential that the satisfaction of this law is
often considered the only condition to be fulfilled in order to realize the beauty of the
work. Pythagoras and Aristotle proclaimed it about 2,500 years ago and almost every
philosopher since then has used this argument when discussing beauty. According to

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these authors, “the beauty is that the characteristics of each object composed of
different elements that create a unity of effects on feelings of the viewer.” The
formula sounds simple, but when you explore its meaning, it shows that it is very
complex, so sometimes the unity of expression and appearance seems hardly feasible.
This definition of beauty is very convenient when it comes to engineering
structures because their fundamental wholeness is in their construction which can be
seen in its totality, regardless of the number of elements they contain. Unlike
buildings, where all of their parts sometimes can only be imagined rather than seen,
engineering structures which, due to their specific functions, can always be
perceptually covered as a whole.
The definition emphasizes the word unity as particularly important. What is unity?
Unity is the quality of the structure through which it is reflected as a final and organic
thing. This unity as a quality is possessed by each structure that leaves the observer
with the impression of a unique composition. Regardless of the level of complexity of
structural elements or spatial wholeness, if the complex elements immediately take
their place as integral parts of the whole, the structure is a unique and good structure,
as shown in Figure 2.

Figure 2 – Gwazi – An interwining trill for car races, Buches Gardens Tampa Bay, Florida
(http://www.streetergroup.com/pages/eng-coasters_gwazi.html)

Ivo Andric, laureate of Nobel Prize for literature in 1961, won this prize for the
novel “The Bridge on the Drina”. His words of appreciations were: “Out of all things
that human beings raise and build in their vital propensity, nothing is better and more
valuable to my eyes than bridges. They are more important, more sacred than houses;
they are more civic than temples. They are equally useful to all, being always built
with high carefulness, in places where most of human needs meet, more durable than
other constructions and without serving evil or hidden purposes”.[3] A stone bridge
from the 16th century, an endowment of Mehmed-pasha Sokolovic, like a mute

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witness remembers the seeming harmony of different cultures, religions and people
whereas deep antagonism exists between them .[8]
The construction of the bridge represents the apogee of the Ottoman monumental
architecture and civil engineering. It consists of 11 masonry arches with spans of 11m
to 15m, and an access ramp at right angles with 4 arches on the left bank of the river .
[7] The 179.5 m long bridge is a representative master piece of Mimar Sinan, one of
the greatest architects and engineers of the classical Ottoman period and a
contemporary of the Italian Renaissance, with which his work may be compared as he
is also known as Turkish Michelangelo. The unique elegance of proportion and
monumental nobility of the whole site bear witness to the greatness of this style of
architecture as it could be seen on Figure 3.

Figure 3 - The Bridge on the Drina, designed by Kodza Mimar Sinan

http://www.palelive.com/visegrad/

Everybody who once sees this bridge is fully aware of its beauty, but we all cross
other bridges or go nearby them sometimes unconcerned, since they are already
integrated into our usual landscape which we perceive and memorize as part of our
everyday life. We may admire them without knowing anything about their history:
who had the vision about their elegant lines and who transposed them into plans, and
materialized those plans into engineering structure. Not even the time lapse in which
they were built.
The skill of builders working on such a large structure is reflected in respecting the
principle of maintaining the basic line simple, with the regular repetition of main
motifs, usually arches in case of stone bridges. In this way, they were able to create a
unity from the complexity of the whole, forming a bridge structure which perfectly
meets the first and probably most important requirement of beauty. In Latin it is
defined in the ancient times using the phrase E pluribus unum (one out of many), and
it is stated liveliest in bridge construction.
However, we can easily miss this valuable impression of unity of the continent.
One of the first ways to achieve the unity of the structure is the repetition of the same

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motif, but this repetition of motifs, if done improperly can produce monotony or
ostentation and confusion. All the structures, good and bad, have a certain degree of
complexity. One must have not only practical but also aesthetic reasons. The absolute
uniqueness, if such a thing is possible at all, can cause wonder and amazement, awe,
but never satisfaction as one of the impressions that beauty gives.
It is practically impossible for the builder to design a engineering structure which
is simple. Connecting all the different units into a comprehensive work is the largest
aesthetic problem and involves establishing a relationship between them, so that each
of them meets the required aesthetic level, and each unit can establish its own
relations with any other unit, as well as with the wholeness of the structure. How can
this be achieved in structure design?
The best way to answer this question, so important both for the person who
evaluates and assesses the bridges and the designer who uses that experience in his
work, is to find the dominant qualities, i.e. properties, common to all beautiful and
whole structures. These qualities were often analyzed through the history and after
analyzing the results, they were gradually codified in laws or rules of the artistic
composition. In short, these are rules of balance, rhythm, good proportions, climax
(peak, centre, the main motive), and harmony.
The first requirement of aesthetics is the law of balance that can be expressed in
the following: each structure should be composed so that its parts on both sides of an
imaginary line in the eyes of the observer create the impression of having the same
weight. The simplest application of this law can be seen in symmetric structures,
while the more complex implementations are realized in the so-called picturesque and
asymmetric structures, as seen in Figure 4. Simpler schemes are more successful, and
the difficulty in arranging the composition increases with the addition of motives,
since the increase in complexity makes it difficult for the eye of the observer to
immediately perceive the present balance, which is an element of beauty of the whole.

Figure 4 – Suger silos in Halfweg, Netherlands ((http://www.a10.eu/materials/sugar_crystals.html)

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It is much more difficult to understand the application of the law of balance in

asymmetric structures. At first glance, the asymmetrical structure may seem to be out
of balance, but its beauty cannot be denied. The world would be a boring place if
every structure or building was absolutely symmetrical. There is a range of structures
worth mentioning which possess a free and obvious charm described by the term
picturesque, such as the coffe and tobacco factory built in late 1920's presented in
Figure 5.

Figure 5 – De van Nellefabriek, Rotterdam, Netherlands

(https://geolocation.ws/v/P/52312347)/
The second important law of artistic creativity is the law of rhythm that can be
expressed by the definition that every beautiful structure should be composed so that
its units have some rhythmic relations among themselves. Again, unlike most
buildings in which it is difficult to set a specific group of elements that will be
repeated in the same form without interruption, in engineering structures it is vastly
present. It is this continual repetition of the same rhythmic form, almost of the same
dimension what provides many structures with the impression of strength and
comprehensive monumentality as it presented in Figure 6.
Closely related to the issue of rhythm is the following the law of aesthetics – the
law of proportions. This law says that every beautiful structure should be well
proportioned. Good proportions are the quality of every structure whose relationships
between the parts are making a satisfactory impression. It is more about the quality of
the relationship of all the structural elements than about the quality of each individual
element. Some claim that the sense of good proportions is achieved when the
structural elements are in simple arithmetic proportions, such as two and three, two
and four; with this in mind, some efforts were made to codify mathematically what is
a good proportion. The designer may have the final idea of relationships in his mind
while creating a vision of the structure, but the best design is always generated by
continually and freely matching the dimensions and ratios of the structural elements,

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until a unique beautiful design is achieved and a "good proportion" ensured. In a good
structure, each element, no matter how beautiful, is in fact only part of the whole and
as such should always be evaluated. [23] An example of well achieved proportions
can be seen in Figure 7.

Figure 6 – New runway of the Funchal Airport, Madeira, Portugal

(http://www.oddee.com/item_93109.aspx)

Figure 7 - The "Gazela" bridge over the Sava River in Belgrade

(http://www.dizajnzona.com/forums/)

When considering proportions in this wider manner, it is clear that the law of
proportions is closely related to the next important law of aesthetics, which says that

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the bridge should be harmonious in order to be beautiful. Bridge harmony covers

much wider field than only the harmonic proportions of various elements. There also
should be a harmony of expression and to some extent a harmony of style: in short, in
a beautiful bridge, not a single element should be designed to look strikingly
different, lonely and isolated from the whole, because in this way the bridge loses
unity in the eye of the observer, and without unity there is no beauty. Thus, harmony
is threefold: harmony of proportions, harmony of expression, and harmony of style.
There is also one aesthetic rule or canon that should be considered carefully – the
law of climax. The need for climax, a point on the bridge, more interesting than all
the others, has already been mentioned in the discussion on balance. The eye,
wandering over a large structure, becomes tired when lacking a single feature where it
can rest; thus, eye fatigue is fatal to beauty in the same way as mental fatigue is fatal
when reading a long prose without any climax where the mind can rest. In
architecture, the need for the centre of interest is expressed so carefully that the
climax may become inconspicuous, even unnoticeable, but still significantly affects
the quality of the overall experience. However, more frequent are the cases where the
centre of interest is highly pronounced, or hypertrophied. Some critics even believe
that they could be functionally less conspicuous, but they were emphasized for
aesthetic reasons, as presented in Figure 8. Architectural wonder, one of the largest
bridges in the world with a single pylon, in a constructive and visual sense is the pride
and symbol of the capital of Serbia; thus, residents and travelers who come and go
provide the Serbian capital "acceleration".

Figure 8 - The new bridge over Ada island, Belgrade, Serbia

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3. WHO ARE THE CONTRIBUTORS IN AESTHETICS OF ENGINEERING

STRUCTURES?
Firstly, distinction should be made between engineering as a discipline and
personality of civil engineer-designer. The earliest application of architectural
engineering date back to 4000 BC when people had a good strain of mind to create
living conditions for themselves, such as shelters, houses, roads, including bridges
and canals. However, it was not until modern times that there were almost no
distinctions between civil engineers and architects and they were hard to define.
In the mid 13th century the term engineer was introduced which literally means one
who is engaged in military machines. To differentiate from military engineers, the
term structural engineer was coined in the second half of the 18th century, implying
personality who is engaged in constructing roads, bridges, canals, harbours and docks,
drainages and industrial plants. [25]
Until then, all of them were builders, often labelled as architects. There were
certain differences among them. There were authors with more or less capacity to
constructively implement their ideas. If they lacked skilfulness to physically
implement their ideas, they were assisted by others, also builders, possessing a
healthy construction logic which made them more able to realize and improve
engineering structures and other activities pursued today by structural engineers.
Renaissance architects who have left written discussions behind have usually also set
forth their views and advices of how to construct bridges, roads and fortifications.
[19]
The fact is that civil engineering of the 19th century, in its enthusiasm, was
insufficiently interested in architectural expression and integration of spatial
creativity. It was looking only for the most logical, most rational, and best way to
shape its tasks, including bridges. [20] A range of new discoveries were in favour of
the engineering option. At the beginning, it was only a striking change in the
organization of building and improved machinery; thus, it was followed by the
numerous uses of new building materials and structural solutions. New materials,
purposeful such as glass, steel, and concrete were used and experimented without any
hesitation. The advent of new discoveries and the improvement of technical abilities
have significantly changed and diversified the forms of education in a completely
different context than that of future architects. Unusual combinations of advanced
structural systems appeared, such as bridges with cables, but some elements, such as
pylons were still designed in architecture of historic styles, very conspicuous in
Figure. 9. Parallel to architecture, J.A. Röbling, the author of the Brooklyn Bridge in
New York, has also studied civil engineering, and bridge and foundation structures,
which enabled him to design this monumental and utilitarian traffic link over the East
River.
During the 19th century, in some areas the responsibility of caring about the
appearance of the city was divided between the city civil engineer, city architect and
city manager, as it is often the case nowadays. In Amsterdam, for example, the

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construction of the three-aperture stone bridge in 1883 was entrusted not to city
engineer, but to the city architect B. de Greef and his assistant W. Springer, who have
decorated the fence with sculptural lamps too abundantly, as seen on Figure 10.

Figure 9 - New York’s Brooklyn Bridge pylon detail

http://images-gededah.in/2014/06/brooklyn-bridge-suspension-cable/

Figure 10 - Sculptured details of Blauwbrug in Amsterdam

https://www.flickr.com/photos/twiga_swala/4746221665

The battle of interests between civil engineers and architects lasts for a long time,
sometimes aggravated by statements of famous authors. In the late 1900's, the Belgian
painter, architect and designer Van de Velde cynically stated as a fiery advocate of
Art neauveau that "the beauty of engineering structures stems from the ignorance of

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engineers that beauty must be sought." In that period, important and influential civil
engineers emerged, with pronounced sensitivity to design their bridges intuitively,
respecting the aesthetic principles, and at the same time significantly improving
constructive solutions and building technology. However, in certain cases
functionalism prevailed, while the form remained on the level of minimalist solution
that failed to provide a significant visual experience.
As a civil engineer whose opus contains such works, along with works of the
highest anthological value, R. Maillart the famous Swiss author who in his late
bridges applied solutions that significantly changed the philosophy of bridge design
which is often referred to in this context. At the bottom of the aesthetic ladder of his
bridges is the reinforced concrete bridge Zouzi from 1901 over the River Inn, while
the top of his global achievements is taken by the Salginatobel Bridge over the
Salgina Valley, Schiers, also in Switzerland, built from 1929 to 1930. [4] It is enough
to compare these bridges on Figure 11 to see what aesthetic levels can be achieved by
carefully setting and fitting the structure in the context of environment.
Cooperation and disagreement between civil engineers and architects have
continued to the present day, with ups and downs in mutual understanding. The
institution of contest, introduced usually for sensitive locations, historic city centres,
protected natural landscapes, allowed the equality of solutions offered by civil
engineers and architects. It is interesting to note that these solutions are rarely signed
by civil engineers and architects in parallel; the authorship is still that of the architect,
and it is supported by civil engineer or company, and vice versa, i.e. civil engineer
offers a conceptual solution, which is complemented by architect who shapes the
form somewhat more freely.[6]

Figure 11 - Robert Maillart, Zouz Bridge and Salginatobel Bridge, both in Switzerland
(http://structurae.net/structures/zuoz-bridge) (http://en.graubuenden.ch/nature-culture)

Since the influence of architects on engineering structure aesthetics is permanently

present in different ways, the architects' influence on engineering construction is
extended in a specific way. [18] Within the development trends of architecture a
specific form of avant-garde architecture is present, whose proponents are trying to
change the accepted ideas about what a structure should be. The main theoretical goal

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of these architects is to reverse the conventional ideas on the structure, while the main
practical goal for them is to be shockingly new and different, even if their structure is
uncomfortable and disorienting to its users. Treating the structure as an abstract
sculpture and intellectual game, they are known as "starchitects". This approach made
the starchitects highly sought because their buildings, in addition to basic functions,
are given the role of tourist attractions, and the benefit from their popularity is
significant. Parallel to this, and applying the same principles, they also began to
design bridges, TC towers, Some of the today's most extravagant and popular
structures were built by Sir Norman Foster and Santiago Calatrava. Some of their jobs
they realized on contests, some by direct engagement. Boldness in shaping new forms
is their indisputable advantage over other civil engineers and architects, but their
influence is gradually expanding, and an increasing number of cities want to have
sculpturally shaped structures next to an extravagant building by which they will be
distinguished on a world map. However, this new phase of searching for new
aesthetic values of engineering structures also has its ups and downs, because
sometimes the weakness of these ideas are shown in the process of realization, as
happened with the original version of the Millennium Bridge in London, or costs are
significantly increasing during the phase of construction, such as in the case with
some Calatrava's projects, shown in Figure 12.

Figure 12: Millennium Bridge in London, Sir Norman Foster (http://www.janloopersmith.com/)

Samuel Beckett Bridge in Dublin, Santiago Calatrava ( http://www.yelp.ie/biz/samuel-beckett-
bridge-dublin-2)

4. CONCLUDING REMARKS
Exploring the complex and multilayer relationships that historically exist between
civil engineers and architects when it comes to engineering structures designing, it
can be concluded that, despite the competitive spirit which can be constantly felt, this
discourse most often has a happy ending and coexistence is possible to secure in
different ways.[22] [12] However, neither is every civil engineer naturally gifted to be
able to provide high-quality visual experience along with a good functional solution,
nor every architect can feel the movement of forces through the engineering structure
to be able to provide his vision of beauty with security.

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In his book "Philosophy of Structures", Eduardo Torroja, a creator of highly

aesthetic structures writes: “The design of a bridge, even of relatively small span,
presents a serious problem of basic construction and cannot be as simple as the design
of a floor. F. Stüsi, the Swiss engineer, has said: “The problem of long spans has
always fascinated the specialist as well as the layman. The realization of a bridge with
a length of span hitherto unattained, not only requires great technical knowledge and
capability, but also intuition and creative courage; it signifies a victory over the forces
of nature and progress in the battle against human insufficiency.” [24]
Architects are trained to deal with the arrangement of abstract and symbolic forms.
Even if they possess elementary knowledge and constructions, it mainly refers to the
construction of buildings, rather than engineering structures. Very few are those who
have the sense to conceive visual expression that combines forces, balance and load.
As a result, a small number of talented architects can engage in designing a structure
by resolving its primary function. Most architects are able very actively to participate
in upgrading a conceptual project, refining the basic construction by materials
processing, designing fences, lighting, signalling and other necessary parts of the
structure which make it fit in the environment. [14] On the other hand, civil engineers
sometimes lack a sense of beauty and harmony, because they are instructed that their
primary mission is to satisfy the function, or the necessity of overcoming certain
obstacles, while the visual appeal is less important.
Nowadays, the situation is somewhat different, which can be seen by the
increasing number of publications on engineering structure aesthetics intended for
civil engineers. [5] K.E. Kruckemeyer writes: “Aesthetics must be part of the program
for a bridge from the very beginning. They must be an active part of bridge
engineering decisions at every step of the wag, and they must be apart of the careful
application of each detail of the bridge and its approaches. Thus, aesthetics cannot be
fully achieved if they are left to the bridge architect. Aesthetic must become the
province and responsibility of every bridge engineer and, for that matter, of every
administrator. This is true for both the public agencies which are responsible for
bridges and for the in-house and consultant design staffs which design them”.[1]
The conclusion of this discussion about the influence of architects on engineering
structure aesthetics has been formulated very long ago by Leon Battista Alberti. [2]
According to him, beauty is the reasonable harmony, the consonance of all parts of
the body, so that nothing can be added, subtracted or changed, without impairing the
harmony of the whole, while the decor can be defined as a supplement to the beauty.
This stance applies to all built forms, including engineering structures. It follows that
the beauty is a specific essential property (indissolubly bound) suffused by the whole
(structure) body that can be called beautiful; while the decor (fencing, lighting,
signaling...) has the character of something added.

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ACKNOWLEDGEMENT
This paper has been undertaken after part of the Project 36042 supported by Ministry
of Education and Science of Serbia

REFERENCES
[1] Aesthetic Guidelines for Bridge Design (1995), Office of Bridges and Structures,
Minnesota Department of Transportation.
[2] Alberti, L.B. (1452/1988) De re Aedificatoria/On the Art of building in ten
books, (translated by Joseph Rykwert, Robert Tavernor and Neil Leach), MIT
Press.
[3] Andric, L.B. (1977), The Bridge on the Drina, University of Chicago Press.
[4] Billington, David P., Robert Maillart and the Art of Reinforced Concrete,
Architectural History Foundation, 1991
[5] Bridge&Structures Architecture, WSDOT Bridge Architect Services,Washington
State Department of Transportation.
[6] Bridge Architecture and Aesthetic, (2015), In Bridge Design Practice, Caltrans,
211-237.
[7] Celic, Dz. and Mujezinovic M. (1998), Stari Mostovi u BiH, Kulturno nasledje.
(in Bosnian)
[8] Chabouh-Akšamija L. (2010), Arhitektura svrhe: Akcentiranje kamene mostovne
konstrukcije otomanskog perioda na Carskom bosanskom drumu. Sarajevo. (in
Bosnian)
[9] Faber, O. et al. (1944), “The Aestethic Aspect of Civil Engineering Design”,
Series of six lectures delivered for the members of the Institution of Civil
Engineers, Journal Ins. C.E.
[10] Florea, S. and Ionescu, C. (2012), The Bridge – Creation, Passion and
Knowledge, Bridges in the Romanian Geographic Area, S.C. Media Drumuri
Poduri S.R.L.
[11] Fowler, C.E. (1929), The Ideals of Engineering Architecture, Gillette Publishing
Company.
[12] Gauvreau, P. (2002), “The Three Myths of Bridge Aesthetic”, In Developments
in Short and Medium Span Bridge Engineering 2002 , (ed. P. H. Brett, N.
Banthia, and P. G. Buckland), Montreal: Canadian Society for Civil Engineering.
[13] Goldblatt, D. and Paden, R. (eds.). (2011). The Aesthetics of Architecture:
Philosophical Investigations into the Art of Building, The American Society for
Aestetics,
[14] How Can the Architect Contribute to a Sustainable World? (2001), Wingspread
Proceedings (Compiled and edited by John P. Glyphis), Racine, Wisconsin,
Second Nature.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[15] Heyman, Jacques (1999). The Science of Structural Engineering. Imperial

College Press.
[16] Hu, N. et al. (2013), “The Gift of Nature: Bio-Inspired Strategy for Developing
Inovative Bridges”, Journal of Bionic Engineering 10 (2013), 405-414.
[17] Katanic, N. and Gojkovic, M. (1961), Gradja za proucavanje kamenih mostova i
akvadukta u Srbiji, Makedoniji i Crnoj Gori, Beograd. (in Serbian)
[18] Kinderman, P.D. (2009), Bridge Architecture of the 21st Century, A Bridge
Architect’s Perspective, Transportation Research Board, Bridge Aesthetic Sub
Committee, Washington State Transportation Department.
[19] Palladio, A. (1570/1965), The Four Books of Architecture, Dover Publication.
[20] Petroski, H. (1996), Invention by Design, How Engineers Get from Thought to
Thing, Harvard University Press.
[21] Salvadori, M. (1980). Why Buildings Stand Up, The strength of Architecture,
W.W. Norton&Company, INC, New York. 1980.
[22] Tessmann, O. (2008), Colaborative Design Procedure for Architects and
Engineers, Dissertation an der Universität Kassel.
[23] Tonkovic, K. (1985), Oblikovanje mostova, Zagreb, Tehnicka knjiga (in
Croatian)
[24] Torroja, E. (1958), Philosophy of Structures, University of California Press
[25] Wittfoht, H. (1984), Building Bridges, History, Technology, Construction,
Beton-Verlag

[521]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Jasmina LUKIĆ
Aleksandar MILOJKOVIĆ2
Novica STALETOVIĆ3

CONCEPT OF ARCHITECTURAL DESIGN AND CONSTRUCTION

OF RAILWAY PASSENGER TERMINALS
Abstract: Railway passenger terminals are only a part of a whole series of spatial, organizational and
functional entities - various railway stations and infrastructure facilities, which together form a railway
junction. In this paper, exposed material refers exclusively to passenger railway station buildings.
Through analysis and reasoning basic principles and norms necessary for the proper approach to design
these types of facilities are outlined. The aim is to explain the way of operation and the methodology of
design, construction of passenger railway terminal in an efficient and concise manner.

Кey words: Rail passenger terminals, operation, design, dimensioning, construction

KONCEPT ARHITEKTONSKOG PROJEKTOVANJA I

KONSTRUISANJA ŽELEZNIČKIH PUTNIČKIH TERMINALA
Rezime: Železnički putnički terminali su samo deo čitavog niza prostornih, organizacionih i
funkcionalnih celina – različitih železničkih stanica i infrastrukturalnih sadržaja, koje zajedno čine
železnički čvor. U ovom radu izložena materija se odnosi isključivo na putničke železničke stanične
zgrade. Kroz analize i obrazloženja naglašeni su osnovni principi i norme neophodne za pravilan pristup
projektovanju ove vrste objekata. Cilj rada je objasniti način funkcionisanja, metodologiju projektovanja
i konstruisanja putničkih železničkih terminala, na efikasan i sažet način.

Ključne reči: železnički putnički terminali, funkcionisanje, projektovanje, dimenzionisanje,

konstruisanje

1
Ass. mr FTN, Knjaza Miloša 7, 38220 K.Mitrovica, jasmina.lukic@pr.ac.rs
2
Doc.dr GAF, Aleksandra Medvedeva 14, 18000 Niš, aleksandar@garagegroup.net
3
Vanr.prof.dr Fakultet za ekologiju i zašitu životne sredine, Univerzitet UNION – NIKOLA TESLA, Cara Dušana
62-64,11000 Beograd nomstale@open.telekom.rs

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1. INTRODUCTION
Railway passenger terminals are generally huge objects, which represent, due to
their attractive form, dominant and functionally important objects among other ones
in a city where they are located. They are spots where flows of passengers change
their directions, as some passengers start their journey at the same time when the
others end it, while some passengers change trains, from one train to another, and the
other passengers after disembarking from the train change to another form of
transportation - road, water or air.
Design process of railway passenger terminals depends on the strict normatives of
proper dimensioning and complex demands from technical and technological
relations.

2. ARCHITECTURAL SOLUTION AND CONCEPT OF THE OBJECT

2.1. FUNCTIONAL ORGANISATION
The basic elements which constitute the railway passenger station are station
square, railway passenger terminal and railway installations, so the mere passenger
building is connected with the platforms on one side, and on the other side with the
station square, which is actually a connection between the railway station and the city.
Functional concept of the object and final architecture of the whole station
complex are determined by the terrain configuration, so the railway passenger
terminal can be positioned at ground level, in a cut or in an embankment, partially or
completely dug in.
Depending on categories of travelers, capacity of the building, and type of railway
station, it is determined a type of rooms in the passenger building, their size and
interconnectedness.
Passenger railway station terminal consists of the following functionally different
sections: [6]
 Section intended to provide the necessary services to passengers,
 Administrative section where railway business is performed,
 Technical section where trains are drawn in and dispatched out.
The section intended to provide necessary services to passengers consists of part
that make service facilities related to travel and all other facilities - catering, trade,
crafts and entertainment.
Utility contents reffered to travelling are related to the processes of the arrival and
the departure of passengers. This include: [3]
 entrance hall - the vestibule,
 ticket offices,
 info-desks,
 waiting rooms,
 luggage rooms,

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 wardrobe,
 information systems, public toilets and
 platforms and platform shelters.
Entrance hall is one of the most important and the biggest station rooms since it
is found to be a connection between the platform and the station square.
The basic demands which must be met in the hall designing are:
 the hall should be spacious enough so passengers could move without
obstruction,
 the hall should be functional with clearly noticable walking lines for users, the
entrances and the exits,
 the hall should be connected with the other station rooms, but without any
intersected moving flows,
 the hall should have exits for the first platform,
 the hall should be positioned in the same level with the station square (insofar as
the terrain configuration does not impose another solution),
 the hall should be properly lighted, ventilated and easily surveyed.
Considering that station hall is the most attractive area of the railway passenger
terminal, a special attention should be given to chairs, trash cans, water and green
areas, information system elements, and a large wall clock.
Ticket offices or counter halls are intended for purchasing all the types of travel
documents. They are located in the entrance hall of the railway passenger terminal.
Their best position is sideways, to the right, or frontally to direction of passengers
movement from the station square to the station platforms. They must be clearly and
easily noticeable.
Info desks are located in the entrance hall, laterally or frontally to the direction of
movement from the station square to the platforms, although they may be organised
as separate, differently shaped spatial elements.
Waiting rooms are used by departing passengers and persons accompanying
them, as well by persons waiting for someone. They are divided according to classes
(I, II and III), and according to categories of passengers (VIP, military, and waiting
rooms for mothers with small children). They differ in applied standards, interior
design, equipment and furniture and their quality. [7] Тhe concept of passive waiting
is already considered outdated, while the concept of active waiting is more present
through using a variety of catering, commercial, servicing or craft facilities. It does
not refer to the waiting rooms for mothers with small children and the VIP waiting
rooms.
Luggage-baggage rooms provide the service of reception and transportation of
heavy and bulky pieces of luggage, which could be handed in at the departure stop,
and collected at the arrival stop; they serve the purpose of reception, storing, sorting
and issuing bulky pieces of luggage which is transported with the same speed as
passengers. They need not to be directly connected to the entrance hall, but they must

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have a propper conectedness with station platforms. The luggage is transported to the
train by handcarts or electrical vehicles.
Wardrobes for temporary storage of luggage used by arriving passengers -
tourists, persons on business trips, passengers who switch the trains in a certain
station, as well by some of departing passengers (specifically in tourist areas), so it is
essential the wardrobes to be placed on the path of movement of arriving passengers,
although their position should be convenient also for departing passengers, what
depens on size of the station.
Information systems are integral parts of the proper functioning of railway
passenger terminals. They can be audible and visual systems.
Public toilets are to be used by all users of railway passenger terminals. Upon its
position, this facility need not to be within the station hall, but must be in its
immediate vicinity. Depending on the size of the terminal there can be one or more
toilets.
Other facilities for passengers and other users of railway passenger terminals are
not directly related to traveling, but certainly affect the achievement of higher level of
quality in service delivery. They are cattering, shopping, service, craft and
entertainment facilities.
Catering facilities are the most topical among all supporting facilities. How much
they would be attended depends on their general quality: position, interior design,
asortment and service quality. These include [3]: station restaurant, coffee shop, fast
food restaurant, coffee bar, grill, pizza parlor, pastry shop, pub, etc,
The station restaurant and the cafe are very important facilities in the railway
passenger terminal, which affect the quality of the service provided for passengers. It
is necessary they to be organised on the line of movement towards the platforms, or to
station market, but in such a way in which the basic movement flows would not be
hindered. They can be organised as separate areas or as integrated ones, what is much
more favorable, since a common kitchen serves them all. Considering their
organisation, serving in the restaurant and cafe is done in the classical "a la carte"
way, while in a fast food restaurant it is done in the self-service way.
Shopping facilities in scope and type depend on the capacity of the terminal. They
can be groceries, shops for daily newspapers and magazines, cigarettes, souvenirs,
gifts, and jewelry, as well as flower shop, bookstores, perfumeries, etc. It is desirable
that only groceries and shops for daily newspapers and magazines are positioned
within the entrance hall, and all the others can be on the way towards the platforms or
the station market. The latest trends in designing different types of traffic passenger
terminals suggest realisation of complex, multifunctional, so called hybrid objects,
where the terminal and shopping would make a conglomerate of different, advanced
functions, unified by the single site - the common central hall.
Service facilities are to be found for providing services for the terminal customers
in post offices, banks, exchange offices, travel agencies, etc. If it is possible, it is

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desirable that all these activities are organised as a part of the entrance hall.
Otherwise, they must be clearly defined by pictograms.
Craft facilities are to be found for providing services for the terminal customers in
hairdressing salons for both sexes, photographic and optic shops, watchmaker's shops,
key cutting shops, copy shops, etc.
Leisure facilities enable for the terminal customers various amenities in order that
waiting time quickly passes. These include variety of slot machines, internet cafes,
cinemas, etc. It is not necessary they to be positioned within the entrance hall.
The administrative section of the railway passenger terminal enable proper
performance of all the functions incorporated there. These include: management,
administration, train dispatching service, security-telecommunication and service
facilities.
Administration performs tasks that are identical or very similar to the
administration tasks of any other object types. Its composition depends on the
capacity of railway passenger stations. It may include: director, director assistant,
legal department, commercial department, economic services, business manager, and
revenue control department, technologist of the station, traffic inspector and school
inspector. Beside these facilities, there are: meeting room, classroom, archives, a
restaurant for staff with kitchen and all accompanying facilities, sanitary rooms and
staff entrance.
Management consists of: station manager, station manager assistant and
operational assistant.
Train dispatching service is the basic operational service, and traffic flow in the
station depends on it.
Safety-telecommunication devices are designed to ensure safe and secure traffic
flow, as well as for establishing a connection between two stations or station and
locomotive. In designing of this segment of the railway passenger terminal, it is
necessary to be consulted relevant experts.
Service facilities help the overall operation of the railway passenger terminal.
Most of the contents of these areas are standardised, as with the other architectural
structures.
The connection with the platforms some official facilities must have, while
some do not need.
The main conditions which must be defined during the design of railway
station terminals are:
 capacity of the station (small, medium, and large)
 position of the station building in relation to the tracks (in the plane of the
ground, in a cut or in an embankment, partially or completely dug)
 categories of the passengers using the station (departing passengers and arriving
passengers, passengers in transit and passengers in local transport) and

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 diagram of technological process (flow and movement of passengers during

arrival and flow and movement of passengers in departure).
The basic requirements that must be met when designing passenger railway
stations:
 it is desirable to be managed a separation between major flows of passengers and
luggage according the categories and directions of movement already at the very
station square, which could be achieved by setting adequate entrances and exits,
as well as the separation of rooms that serve for different groups of passengers
and baggage, and special path of movement to the platforms and vice versa,
 station must be comfortable for passengers, including proper organisation of
arrangement of basic passengers’ rooms, so that a passenger could gradually
accomplish all necessary steps, according an appropriate order of actions,
 paths of movement through the station must be as simple and short as possible,
having no intersections, while maintaining quality,
 possibility for extending the station should be predicted, based on a unique
architectural idea, which means that it must be reserved an appropriate territory
for the development of the railway tracks, setting up access to the station, as well
as for new public transport stops,
 technical and other operations should be performed neatly, accurately, fast and
imperceptibly for passengers.
The basic principles that must be followed in designing the railway passenger
terminal are:
 spatial relations should enable a good flow of passengers, following the direction
of their movement, as well as a comfortable stay in the waiting rooms,
 rooms for performing certain functions must be arranged in a logical order,
whereby the actual capacity must be properly dimensioned,
 unified space must be clear and corridors must be reduced to a minimum.
The basic principles to be followed when designing passenger station building
are: [1]
 when entering the station building, passenger must be easily oriented and must
quickly perceive the most important spatial units according to their function,
 direction of movement of arriving and departing passengers - from the ticket
office, the luggage room, wardrobe, and waiting rooms towards the train and
back must be as clearly marked,
 accesses to the platform and to the station building must be direct,
 waiting rooms must be out of range of passers-by.
The functional concept of the object and the final architecture of the whole complex
of the station are determined by the terraine configuration, so that the railway
passenger terminal can be at ground level, in a cut or in an embankment, partially or
completely dug in.
The easiest solution is if the entire building is positioned on a single level or at the
level of the station square.

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However, if the station square is 3 - 5m below or above the platform due to the
terrain configuration or for other reasons, what allows an entire floor to be
constructed, at the level of the square is placed a vestibule with operative rooms, the
waiting rooms and the restaurant are raised or lowered to the level of the basic
platform, where the official and some other rooms are positioned. In this case, access
to the platforms are from tunnels or from walkways.
Two-level station should be designed even a large station is needed, but the station
square and platforms do not have enough or required area. In, this way, the
passengers are maximally brought closer to the platforms, which are easy to be
surveyed. In this case it is achieved the illumination of the whole station building.
When conditions permit, one of more favourable variant is a station building with
basement, because it is suitable place where the luggage room and wardrobes for
temporary storage of baggage may be placed, which are connected with ground floor
by freight elevators, as well toilets and utility rooms of restaurants. In this case it is
advisable the ground of the first floor to be raised 1 m above ground level of the
station square, resulting in natural daylight of the basement. Thereby, station building
gets a certain monumentality, because it is raised and the entrance is emphasised by a
wide staircase.
2.2. CONSTRUCTIVE SOLUTION AND APPROACHE TO MODELING
One of the important factors that affect the functional organisation quality of the
railway passenger terminal is the proper arrangement of the structural load bearing
elements, as of the terminal as well of the platforms.
Covering the platform is what especially characterises this space, in order to
ensure complete smooth functioning, independent of weather conditions, so that the
main passenger terminal that follows the entire length of the platform and its
architecture defines the ambience of the area. The designers, when designing these
types of facilities, intend to achieve a greater range of structural, load-bearing
elements and as more elegant design. This is most easily accomplished by glazed
steel frameworks in the form of arches, which unify platform area and, by their
transparency make light enters the space, forming a covered street. That covered
platforms have become the most original part of the architecture of railway stations.
The basic characteristic features of the station buildings consist of a particularly
distinctive large entrance and vestibule, which should dominate the rest of the
building, thus indicating a great care for the architectural treatment of the main look
toward the city. This is achieved by large glass surfaces, broad front of access, a great
shelter in front of the entrance, which emphasizes the specificity of the object.
Today's railway passenger terminals represent the top of modern architecture and
engineering.
Fig. 1 - Kanazawa, Japan - represents a synthesis of traditional Japanese design and
futuristic architecture. Entrance into the passenger terminal is 14m high. The dome is
impressive, consists of 3,000 glass plates.

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Fig. 2 - Southern Cross Station is popular for its undulated trapezoidal roof system
covering an entire city block of about 60,000 square metres. It is 23m at its highest
point. The roof was specially designed to allow the diesel fumes, hot air and exhaust
gases to move upwards and be dispelled through louvres using the force of the
existing winds.The project also witnessed the use of etthylene tetrafluoroethylene
(ETFE) for the first time in Australia for constructing a building. The roof system
provides sufficient ventilation and daylight.

Figure 1 – Kanazawa, Japan Figure 2 – Southern Cross, Australia

Fig. 3 - Shanghai South Railway Station has a circular base. It is the first object of
such form and for that purpose in the world. Its radius is 307m, and the highest point
is at 47m height, where the central area within the radius of 150m is completely free
of columns. The supporting structure consists of 18 steel, radially arranged primary
carriers, a forked shape. Secondary steel girders are supported on it, there are 34
peaces in each field. The dome is closed with polycarbonate plates, over which it is
set fixed aluminum sunbreaker system. [4]

Figure 3 - Shanghai South Railway Figure 4 - High-Speed Train Station, Napoli

Station

Fig. 4 - High-Speed Train Station, Napoli - The primary concept of the passenger
terminal is the bridge that stretches across all the railway lines, forming a pedestrian
passage that connects both sides of the station. This dynamic is achieved by using
concrete and glass.

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Fig. 5 - Grand Canary Wharf Crossrail Station, London - whole of the station is
located in the waters of the Canary Wharf with the North Dock. The space above the
water is made of aluminum profiles, which are fixed to the triangular roof grid. The
modules that make up the triangular structure of the roof are of transparent ethylene
tetrafluoroethylene (ETFE) plastic, that allows penetration of the natural light in the
interior space. Some modules are omitted, allowing rainwater to fall in vegetable
central garden.

Figure 5-Grand Canary Wharf Crossrail Figure 6-Haramain High-speed Railway

Station Saudi Arabia

Fig. 6 - Haramain High-speed Railway, Saudi Arabia – it is made of square grid of

columns in the range of 27m, 25m in height, above which are formed arches, creating
a vaulted roof.
Fig. 7 - Gare de Liege Guillemins, Belgium - The entire building of the railway
passenger terminal makes the roof structure in form of a massive dome, 200m long,
73m wide, with a cantilevers long 156,25m, heigh 35,35m. It consists of 39 primary,
parallely positioned steel ribs, with the secondary beams, which make up an
impressive unity. Both sides rest on steel pedestrian bridges, while each of them rest
on five strong four-part steel columns, so-called quadripodes. [4]

Figure 7 - Gare de Liege Guillemins

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3. CONCLUSION
After the basic concept of organization of railway junction and network are
adopted in accordance with the mission and location conditions, when designing the
railway passenger terminal, some functional requirements must be met, and they are
seen through analysis approach, respect of spatial relations, proportions, and size,
through equipment, design the overall architecture building, proper lighting and
choice of material and arrangement of structural, load-bearing elements, in order that
they would not be an obstacle in fulfilling the functional requirements.
By meeting the above requirements and principles it is provided the maximally
good organisation of functional process, comfort and economy of the general
structure of the passenger terminal, as well good solution of architectural, artistic and
constructive tasks. All these factors affect the passenger who, entering the city,
acquires the most favourable impression.

REFERENCES
[1] Beširević, Sadik (1997): Organizacija železničkog saobraćaja, Sarajevo: Fakltet
za saobraćaj i komunikacije; Univerzitet u Sarajevu
[2] Dobrović, Nikola (1953): Tehnike urbanizma 2A, Beograd: Naučna knjiga
[3] Fejzić, Emir (2011): Funkcionisanje i proračun željeznčkih putničkih terminala.,
Sarajevo: University Press; Beograd: Građevinska knjiga.
[4] Fejzić, Emir (2011): Suvremeni željeznički putnički terminali., Sarajevo:
University Press; Beograd: Građevinska knjiga.
[5] Vasiljev, V., Cetinin, N. N (1967): Arhitektura želznodorožnih vokzalov. Moskva
[6] Stevanović, Ksenija (2008): Renesansa železničkih terminala, Beograd:
Zadužbina Andrejević

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Aleksandra MILINKOVIĆ
Ljiljana VUKAJLOV2
Dijana BRKLJAĈ3

INFLUENCE OF ORGANIZATION AND CONTENT OF THE YARD

OF URBAN BLOCK ON THE SOCIALIZATION OF RESIDENTS
CASE STUDY - THE LIMAN BLOCKS IN NOVI SAD
Abstract: The Limans are a part of Novi Sad through which the high culture of living, different sub-
typology of residential architecture, the morphological genesis of freestanding and buildings in a row, as
well as urban premeditation of contents in an approximately correct, orthogonal street scheme are
reflected. Four blocks of similar size, shape and contents that are present in them, visible on the territory
of Liman I, II, III and IV are going to be analyzed in this paperwork. The aspects, according to which a
comparative analysis will be carried out, have aim to draw attention to the current problems and urban
omissions that could provide and outline proposals and recommendations that would contribute to the
overall social prosperity on a micro ambience levels.

Кey words: urban block yards, socialization, activities, open space.

UTICAJ ORGANIZACIJE I SADRŽAJA UNUTARBLOKOVSKIH

PROSTORA NA SOCIJALIZACIJU STANOVNIKA
STUDIJA SLUČAJA - BLOKOVI NA LIMANIMA U NOVOM SADU
Rezime: Limani su deo Novog Sada kroz koji se odražava visoka kultura stanovanja, razliĉite
podtipologije u stambenoj arhitekturi, morfološka geneza slobodnostojećih i objekata u nizu, kao i
urbanistiĉka osmišljenost sadržaja na otvorenom u približno pravilnoj, ortogonalnoj šemi ulica U radu će
biti analizirano ĉetiri bloka, ujednaĉena po veliĉini, obliku i sadržajima koji su u njima prisutni, izdvojeni
na teritoriji Limana I, II, III i IV. Aspekti prema kojima će se raditi uporedna analiza imaju za cilj da
ukažu na trenutne probleme i urbanistiĉke propuste koji uz adekvatna rešenja, sa detaljnom analizom i
valorizacijom postojećeg stanja, mogu da pruže i ukažu na predloge i preporuke koje bi doprinele
ukupnom socijalnom prosperitetu na nivou mikroambijenata.

Ključne reči: unutarblokovski prostori, socijalizacija, sadržaji, otvoreni prostor

1
Teaching Assistant, Faculty of Techical Sciences, Trg Dositej Obradović 6, aleksandrabandic@gmail.com
2
Associatet Professor, Faculty of Techical Sciences, Trg Dositej Obradović 6, ljiljavukajlov@sbb.rs
3
Teaching Assistant, Faculty of Techical Sciences, Trg Dositej Obradović 6,dijana_apostolovic@yahoo.com

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1. INSTRUCTION
The city's complex nature and its genesis are discernable in the intricate
morphological organization that is a product of numerous decade-long
transformations of the urban tissue and maturation of the society that shaped it. The
city is thus a far more complex "social being, than occasional reviews of its social
history may imply" [7]; therefore, the reading of its layers through the eyes of its
inhabitants itself found more modern interpretations. Spatiousness and territorial
growth of settlements do not allow it to become a single entity in the eye of its
beholders, which is why a comprehensive image of particular micro-nucleuses is
rendered impossible. Spatial and morphological changes imply a heterogeneous
physical structure, leading to incoherence and division of the whole into smaller areas
and ambiences.
From an urban planning perspective, Novi Sad clearly illustrates a modern concept
of european cities' development. Formation of urban quarters is long finished, but
internal transformations are under way, so as to meet contemporary functions and
demands. The city is clearly divided into more than 25 quarters, a strong indicator of
its urban-social tradition. Each of the quarters represents a concept of creating a "city
within a city" and formation of territorially distinct, yet economically, architecturally,
socially and ambientally, closely bound urban fragments. Functional and
morphological inconsistency of urban districts raises the overall quality of urban
quarters and meets most needs of its inhabitants.
There are no clear examples of mono-functionality as a concept of shaping and
organization of space within the city; however, housing has taken territorial
precedence. A strategic solution to this existential need has brought accelerated
construction and has led to creation of 'young' urban quarters with fragile identities
and a weak socio-psychological concept that required introduction of numerous
urban and architectural, economic, cultural, marketing and other factors. "Building
construction becomes a global skill; contemporary building materials are available to
all and the need for mass-construction, in particular housing, is strong" [5] which
results in districts such as Klisa, Telep, Nova Detelinara, Grbavica to completely lose
their identity in the collective mental city map. In contrast, these districts have very
lively and distinct histories that are sidelined by the modern city builders and urban
authorities alike. A visually unified architecture and spatially indistinctive borders of
urban blocks' construction provide space for non-residential programmes that could
potentially result in higher standard of living; however, such a concept is very rare. In
addition to the issue of socialization of large numbers of people that inhabit these
districts, there are the pressing matters of lack of vegetation and space for pedestrian
traffic, high frequency road traffic, lack of safety, the psychological problem of
inhabitants identifying themselves with their housing districts and decreased living
comfort in the emerging housing fund available on the market.

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2. SOCIALIZATION WITHIN URBAN BLOCKS

"Housing and housing policy cannot be studied outside of their social context,
which gives particular weight to sociology of housing" [6] in the matters of assessing
quality of living conditions and ascertaining public benefits for inhabitants of specific
age categories, who primarily use the designated space. Lack of space, and primarily
healthy physical and mental development, require public programs in the open.
Issues of family inheritance, ambient prestige, functional characteristics, relative
position, sociological or economic lifestyle, greatly depend on urban districts, which
makes it understandable why "Novi Sad inhabitants once identified themselves
relative to their urban district" [7]. Such segregation is much less prevalent nowadays,
since urban districts are much more ambiguous of the origins of their inhabitants.
Unbuilt open spaces inside urban blocks provide a context for social interaction of
their inhabitants, since a person as a social being has the need for public gathering
that cannot be met inside the living unit. Socialization in public spaces is mostly
associated with the youngest and the oldest members of the society; these two age
groups are regarded as most demanding and specific and have, therefore, been taken
as reference for many existing studies.
Children are users that need open spaces to discover through play, whereas parents
want interesting spaces that are absolutely safe and where they can supervise the play.
Throuhg play, a child learns about its surroundings, develops psycho-social and
mental abilities, grows intellectually, and acquires moral traits of its personality. Play
is, according to Peter Gray, a manner for a child to develop free of the need to
dominate and exhibit agression [2]; the viewpoint of numerous other psychologists,
sociologists and pediatricians is dominantly inclined towards positive aspects that
socialization and introduction into the public may bring to a young person, a child in
particular.
On the other hand, there is the pressing issue of limited open space within an
urban block, combined with a large number of users and a clash of diverse needs and
levels of tolerance. Child play begins to disturb, whereas the noise from their
exhilaration and pleasure slowly becomes tiresome even for their parents; there is less
and less playgrounds where children meet, exchange toys and play catch, so that "one
of the most prominent changes to open, public spaces of the last century is the
disappearance of children." [3] The elderly also face lack of appropriate programs that
would complement and enrich their daily schedules. Sports' courts are seldom, both
for the youth and those targeting older. Open spaces sheltered from the elements,
furnished spaces with cultivated vegetation, urban equipment or atypical programes
are not present in any of the urban blocks' open spaces. There are rare cases that
sections of it are adapted to socialization of the elderly, thus enriching and
complementing their standard of living.

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3. UNDERUTILIZED OPEN SPACES INSIDE RESIDENTIAL URBAN

BLOCKS - CASE STUDY LIMAN DISTRICTS
Envisioned as a grand urban planning endeavour of the second half of the 20 th
century in Novi Sad, the Liman districts have offered exceptional residential
conditions for its inhabitants. Located in the south-eastern part of the city, next to the
Danube river, the districts have utilized the natural and created conditions to leverage
a series of advantages of their location. Consisting of four entities, with a dominant
condominium typology, the Liman districts are, in an architectural sense, districts
with a large number of inhabitants and an optimal ubran density, realized through a
combination of free standing buildings and row housing typologies; it hosts a large
number of educational, health, commercial and business buildings, sheltered spaces
and spaces for pedestrian traffic. Each of the mentioned urban-spatial characteristics
effects the manner in which open space within an urban block is formed and its
programmes, as well as its popularity and the quality of experience they offer.
We selected four control urban blocks for the purpose of this research:
 Liman I: urban block between the Fruškogorska, Draga Spasić, Veljko
Petrović and Jireĉekova streets;
 Liman II: urban block between the Fruškogorska, Resavska, Ravaniĉka and
Narodni Front streets;
 Liman III: urban block between the Car Lazar Boulevard, Balzakova, Narodni
Front and Banović Strahinja streets;
 Liman IV: urban block between the Car Lazar Boulevard, Banović Strahinja,
Narodni Front and Ivo Andrić streets.
As for the selection criteria, they were their immediate vicinity (boundary urban
blocks of each of the Liman districts), residential as the primary building typology,
similar organization of built entities within a block and both more and less frequent
roads at their borders. There is a large number of related factors that have in
combination led to unfavorable conditions for safe visit by children, youth and the
elderly. From the point of view of needs and interests of each age category of users, it
is necessary to offer a series of micro ambiences within the urban block, which would
meet diverse requirements of those who would use it the most.

Figure 1 – Urban blocks without contents in Liman I and Liman II

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Quality of playgrounds and open leisure spaces is questionable in each of the

districs studied. Correct orientation is key in determining popularity of an open space,
which seems not to have been a criterion of design and organization of public spaces
at the time. Furthermore, there is poor urban equipment and fittings, large parking
spaces and active road traffic that decrease safety and increase pollution are often
nearby; choice and position of vegetation is inadequate and it is mostly poorly kept;
minimal attention was payed to meeting the standards of universal design and choice
of materials; lighting is often not provided, decreasing visibility and public safety.

Figure 2 – Basketball court and concrete benches in Liman III

How much sociology, as study of society, is an interesting topic in the Liman

residental districts, may be illustrated by the nature of alterations to the residential
units on the ground floor, barred windows, unfamiliarity with neighbours and overall
resident intolerance. Lack of privacy is an alarming issue in a psychological sense
that leads to a range of anomalies of the society at large; however, this issue is more
prominent in the districts of Grbavica, Nova Detelinara, and Novo Naselje. Residents
of Liman districts is diversified, but it is evident that youger children accompanied by
parents or older chaperones, are the primary users of public open spaces during the
day; also, there is a growing number of residential units owned by senior citizens who
have the need to spend time outside and socialize.

Figure 3 – Football court and children playground in Liman IV

If we observe the issue from this perspective and adopt efficiency and profit as
primary evaluation criteria (which automatically implies a capitalistic predisposition
of the society), one is not surprized by the fact that public open spaces are neglected,

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since they do not generate profit. Spaces within urban blocks not dedicated to
pedestrian traffic render areas of accidental communication, and not those of joy and
socialization. Current problem implies the fact that "by grouping buildings around an
open space" [4] one does not simply result in an area for socialization and leisure, but
rather in a space that requires further creative and strategic planning and design
efforts.
In case of the first urban block, there was a lack of urban furnishing appropriate
for the predominant user age group. The interior of the block is rather cold, cluttered
by high vegetation, in deep shade and damp, which decreases its overall
attractiveness. The location is not used to its full potential and there are no resident
initiatives to this effect. Disinterest is also visible in the case of Liman II urban block.
Smaller, partially opened interior courtyards are not furnished, primarily utilized as
communication paths and spontaneous pedestrian traffic. This block is next to an
elementary school building, which additionally implies that micro ambients with
carefully designed programs could improve socialization and significantly contribute
to a more quality leisure time spent in the open. The situation in Liman III and IV
urban blocks is urbanistically somewhat more favourable. Sports' courts surrounded
by free and green open spaces leaves more possibilities for public gathering of the
yougth. Liman IV urban block also hosts a frequently visited children's playground.
One might, however, question whether the reason for its popularity is genuine quality
verified by objective comparative parameters, and to which extent the lack of similar
spaces in the vicinity has contributed to this.
The current image in studied blocks is also applicable in relation to the seasons.
Sheltered spaces inside the urban blocks are more attractive during the winter, as they
are creatively utilized for children's playtime activities. The changing nature of urban
blocks' open spaces should indeed respond to the seasons and times of day; however,
the visual attractiveness of the space neglected, little attention was paid to ambiental
lighting, furnishing, maintenance of the green surfaces as well as to the variety of
programs that would attract users to visit these spaces more often. Another of the
pressing issues is the lack of residential culture of nearly all age categories,
intolerance and lack of understanding of other people's needs and desires, as well as
lack of initiative to change the status quo.

4. CONCLUSION
Based on the case study of four urban blocks in the Liman districts we illustrated a
series of advantages and weaknesses in the social and ecological sense that affect the
living comfort in these residential urban districts. A city is not a stage for short-term
performances; on the contrary, it hosts a range of spatial levels that contribute
towards healthy and human-centric spaces. Initiative is the first thing needed to
ensure an active public discussion on these and related phenomena in other Novi Sad
urban districts. Existing block courtyards have great potential for reigniting
socialization across all age categories. Due to lack of care by users themselves and the
city administration, these spaces remain underutilized.

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"An urban planner is acquainted with functions to be satisfied; his task is to

assemble a coherent whole from the existing possibilities and given conditions" [1],
both in view of existing built structures, and the free open spaces inside urban blocks.
These spaces are unattractive, uninteresting and unsafe, rendering them desolate and
without a concrete purpose and users that would enrich them and contribute to their
preservation and significance. With certain smaller or larger investments it is possible
to enhance their function, as well as to raise the overall quality of all free spaces and
thus facilitate human socialization.
It is feasible to develop a strategy that would require less resources and facilitate
better utilization of inner-block space. It is, therefore, necessary to negotiate a better
materialization of pedestrian and thematic spaces for children, child-safe playground
furnishing, vegeration control and maintenance, street lighting and visibility of public
gathering spaces. Furthermore, a significant step would be towards introduction of
sports' courts, green spaces for pets, micro-scale ambiences for leisure and
socialization of the elderly, social games in the open. It should be emphasized for the
purpose of further research that the issue of poor socialization is pressing in all
predominantly residential districts; To that effect, in addition to initiative, it is
necessary to propose strategic actions towards transforming particular urban blocks
into spaces of public interest, simultaneously offering higher quality programs and
ensuring healthier growing up and a pleasurable and enriching living experience.

ACKNOWLEDGEMENTS
The paper was done within the project "Optimization of architectural and urban
planning and design in function of sustainable development in Serbia" (TR36042),
funded by the Ministry of Education, Science and Technological Development,
Republic of Serbia.

REFERENCES
[1] Gidion S. 2012. Prostor, vreme, arhitektura. Beograd: GraĊevinska knjiga,
[2] Gray P. 2010. Freedom to Learn,
http://www.psychologytoday.com/blog/freedomtolearn
[3] Dudek M. 2005. Children’s Spaces. Velika Britanija: Elsevier
[4] Krijer R. 2007. Gradski prostor u teoriji i praksi. Beograd: GraĊevinska knjiga
[5] Milinković A. Vukajlov Lj. 2014. Elementi identiteta Grbavice u Novom Sadu,
(NaĊa Kurtović-Folić ed: Tematski zbornik radova: Optimizacija arhitektonskog
i urbanistiĉkog u funkciji održivog razvoja srbije planiranja i projektovanja).
Novi Sad: Departman za arhitekturu i urbanizam, Fakultet tehniĉkih nauka, pp.
493-508
[6] Petrović M. 2004. Sociologija stanovanja, Beograd: Institut za sociološka
istraživanja Filozofskog fakulteta u Beogradu
[7] Pušić Lj. 2009. Grad bez lica, Novi Sad: Medi Terran Publishing

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Marija STAMENKOVIĆ

THE IMPACT OF GREENERY ON SPATIAL ORGANIZATION OF

PUBLIC BUILDINGS
Abstract: Due to high density of construction in city centers, the areas under the greenery are
considerably reduced. It has multiply negative effects concerning conservation of natural environment.
One of the ways to create healthier environment is implementation of greenery within the buildings.
Topic of the paper is the investigation if and how greenery affects the spatial organization of public
buildings, which largely cover city centers. The analyses of the presented buildings were done on the
basis of determined criteria. Research findings indicate that the disposition of greenery, in any case, does
not have negative influence on spatial organization of buildings. It is concluded that this manner of
contemporary design and construction could bring many benefits.

Кey words: greenery, public buildings, spatial organization, contemporary design, urban areas.

UTICAJ ZELENILA NA PROSTORNU ORGANIZACIJU JAVNIH

OBJEKATA
Rezime: Usled velike gustine izgrađenosti u gradskim centrima, površine pod zelenilom su znatno
smanjene. To dovodi do višestrukih negativnih efekata u pogledu očuvanja prirodne sredine. Jedan od
načina stvaranja zdravijih sredina je implementacija zelenila u okviru objekata. Tema rada je istraživanje
da li i na koji način zelenilo utiče na prostornu organizaciju javnih objekata, koji u najvećoj meri
zauzimaju gradske centre. Analize prikazanih objekata su urađene na osnovu utvđenih kriterijuma.
Rezultati istraživanja ukazuju da položaj zelenila, ni u jednom slučaju, nema negativan uticaj na
prostornu organizaciju objekata. Zaključeno je da bi se ovakvim načinom savremenog projektovanja i
izgradnje mogle ostvariti mnoge koristi.

Ključne reči: zelenilo, javni objekti, prostorna organizacija, savremeno projektovanje, urbane sredine.

Assistant at the Faculty of Technical Sciences, University of Priština, Kneza Milosa 7, 38220 Kosovska Mitrovica,
Serbia; e-mail: marijastamenkovic81@gmail.com

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1. INTRODUCTION
Design of public buildings is determined by the legalities which are primarily
referred to the functional schemes of certain types of buildings. They have to be
complied with the aim of proper disposition and grouping of rooms within functional
zones, where rooms are linked by vertical and horizontal communications which
should be characterized by the simplest directions, the shortest trajectory of motion
and good interconnection. Every building type is also characterized by modular span,
structural system, materials of construction, etc. Traditional method of design
considers fulfilment of these requirements, while the contemporary concept of design
adds the requirement of sustainable design. One of the ways to design sustainabe
buildings is the usage of greenery inside or outside the buildings. If and how greenery
affects the spatial organization of public building is investigated in the paper, based
on determined criteria.

2. CRITERIA FOR DETERMINING THE IMPACT OF GREENERY ON

SPATIAL ORGANIZATION OF PUBLIC BUILDINGS
The criteria which are considered in the paper are:
 rooms disposition and their linkage into functional zones – it is investigated if
the presence of greenery affects the rooms disposition within the functional
zones and vice versa,
 vertical and horizontal communications – it is investigated if the greenery
position affects the position of communications and vice versa, and
 floor dimensions – it is investigated if the floor dimensions are changed due to
the presence of greenery.

3. THE IMPORTANCE OF LINKING GREENERY WITH PUBLIC

BUILDINGS
Urban areas are characterized by dense construction and by impermeable areas
which cause multiply negative effects because of the devastation of natural ecosystem
[3]. Some of them are: change of microclimate of the cities – the effect of urban heat
island, increased possibility of flooding, noise pollution, air pollution, etc. [5]. This
can be alleviated by design and construction of green roofs and facades, green areas
inside the building and by design where the ground is minimally used by the building,
which could affect the spatial organization of public buildings.
As the city centers are primarily occupied by public buildings, it is necessary to
fulfill the principles of contemporary design for these types of buildings.
Although the public buildings are intended to periodical staying of workpeople
and visitors, the usage of greenery provides pleasant staying in created natural
environment, which also affects the building aesthetics inside and/or outside.

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4. GREENARY POSITION IN REGARD TO THE BUILDING

Two specific cases of greenery position in regard to the building are investigated
in the paper, and they are:
 greenery inside the building and
 greenery on the outside of the building.
4.1. Greenary inside the building
Greenery inside the building could be placed in the central part of a building, at
the brim or could be evenly distributed. Related to that, three examples of public
buildings are analyzed.
Project of the public Logan Library (Utah, USA; Utah Projects; 2008) (Fig.1)
presents a three level high multifunctional building, with a circular plane (Fig.2).
Central part of the building is a lobby which extends through all levels, and greenery
occupies this area.

Figure 1 – Logan Library [15] Figure 2 – Ground floor [16]

From the presented ground floor, it can be seen that the greenery positively affects
the rooms disposition because it separates different building functions – library and
conference block. At the second floor, open space also has a role to separate different
functions within the library. Discussing the positions of communications, it can be
determined that the position of greenery does not affect the positions of vertical
communications and the greenery is a part of main horizontal communication. The
presence of greenery has no influence on floors dimensions changes. It fills the large
space of the lobby making the building interior pleasant to stay in. Conclusion is that
the greenery inside this building is a positive result of design and spatial organization.
New National Library Building in Singapore (Singapore; Ken Yeang; 2005)
(Fig.3) is a multifunctional multi-level building consists of two blocks linked by
bridges at the upper levels. Multimedia facilities, an auditorium and exhibition space
are in smaller, curved block, while the more traditional library collections are placed
in larger one [9]. The building has two huge gardens, which contain 12m high trees at
the 5th and 10th floor levels. The gardens are placed at the brim of the building, in the
central part of the smaller block (Fig.4). They are glazed on all sides.

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Figure 3 – New National Library Building Figure 4 – Levels under (a,b) and above
[17] (c,d) the gardens [7]

The position of the gardens i.e. air space above them justifies their existence
concerning spatial organization of the library, because they separate “noisier”
activities as a buffer layer [7]. Vertical communications are not directly connected to
the gardens space, while the corridors link the rooms on both sides of the smaller
block. The green space does not have negative influence on corridors position. By the
position of gardens, corridors have access to natural light from both sides, making the
environment close to the nature in densely built urban area. Concerning the influence
of greenery on changes of floors dimensions, it can be determined that the absence of
gardens would change them from 5th level to the top of the building. It would not
reduce occupation of the land, which is a tendency of modern design. It can be
concluded that the presence of greenery within this building was a requirement to
make a low-energy building and to reduce greenhouse-gas emissions.
Contemporary project of the Culture and Art Center “Culture Forest”
(SeongDong-gu, South Korea; Unsangdong Architects; 2010) (Fig.5) presents a
multifunctional building with a specific interior design – closed and mostly open
spaces are connected through greenery which is evenly distributed [8]. The zoning of
different building functions is shown in Figure 6.

Figure 5 – Culture Forest – Open space Figure 6 – Open and closed space zoning
zoning [18] [18]

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Since the greenery is a part of open spaces, its position is justified by the function
of open spaces which are intended to attract visitors through glazed facades. At the
same time, open spaces are the main communications in the building, so the greenery
has positive influence on their position. Concernig floors dimensions changes due to
presence of green spaces, it can be said that they have no negative influence because
the presence of greenery was the basic idea for design of this building, and by that, a
requirement for making healthier environment, achieving energy efficiency and
attractive appearance of the building.
Based on analyzed examples of buildings with different position of greenery inside
them, it can be concluded that the greeney in each case has positive influence on
spatial organization of buildings.
4.2. Greenery on the outside of the building
Greenery on the outside of the building can be directly linked to the building (as
green roof or façade) and indirectly – so its position in the external environment
affects the spatial organization of the building. This reffers to contemporary
requirement of design to reduce the land use and to reduce the negative impact on the
natural environment. Three specific cases are analyzed – greenery on the building in
form of a green roof, greenery indirectly linked to the building and the combination of
first two cases.
ACROS Fukuoka Prefectural International Hall (Japan; Emilio Ambasz; 1994)
(Fig.7) is a multifunctional multi-level building which form steps up in a stratification
of low landscaped terraces with the aim of conservation of park area [14]. The layer
of greenery, as a part of roof construction, also contributs the efficient energy use of
the building [2]. Cross section of the terrace building is shown in Figure 8.

Figure 7 – ACROS Building [11] Figure 8 – Building cross section [13]

Concerning the influence of greenery on rooms position, it can be said that their
position is caused by building form, which is a consequence of a condition for
existance of green area. So, the greenery indirectly affects the position but not the
disposition of rooms. Main vertical communications are placed at the brim of the
highest block and greenery also has indirectly influence on their position [13]. Floors

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dimensions are changed for the purpose to allow the formation of terrace structure
with the aim to extend the park area. The existance of greenery is a requirement of
design, resulting in limited building form well imbeded to the environment.
Project of the National Library building in Astana (Kazakhstan; BIG; 2009)
(Fig.9) is characterized by its specific form. A circle arises and makes spiral form of
the building [6]. A basic motive was to link natural environment – ground and sky
through the building. The building is presented as an inseparable part of the
environment, which is confirmed by its form, concerning minimal land use and
minimal violation of the environment. Inner open space, and also the building
environment, are covered with greenery. In this example, greenery is indirectly linked
to the building.

Figure 9 – National Library in Astana [12] Figure 10 – Zoning of building functions [12]

Zoning of the building functions is shown in Figure 10. They consist of closed and
open spaces, linked to each other. The greenery on the outside of the building has no
direct influence on rooms disposition within functional zones. It is caused by the
building form. The position of vertical and horizontal communications is also
conditioned by the building form and do not directly depend of the greenery. It can be
concluded that greenery indirectly affects building design, and also floors dimensions
changes. This “hover” structure meets the requirement of contemporary design by
conservation of natural environment.
Project of the New Taipei City Museum of Art – Artscape (Taiwan; HWKN;
2011) (Fig.11) resulted from the designers idea to integrate the building into natural
environment [10]. The form of a hill is intersected by passages in the ground level,
creating separated parts of the building, while the building form is compact at the
underground levels (Fig.12). In this example, greenery is directly linked to the
building – in a form of green roof, and also indirectly – making the green area as the
building environment without clear boundaries from outside.

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Figure 11 – Artscape Museum [10] Figure 12 – Building cross section [10]

Created passages enable access to each part of the building, which presents a
particular functional zone, at the ground level. Greenery in a form of green roof does
not affect the rooms disposition directly because it is caused by the created building
form. Its position is well used for the requisite of the building underground function.
As the exhibition space, placed at the underground level, requires indirect or artificial
light [4], the greenery disables penetration of direct solar radiation and, at the same
time, has an insulation role. Main vertical communication is placed in the central part
of the building, and greenery does not have negative influence on its position.
Concerning the idea of merging this new space with the environment, it can be said
that the greenery affects the building form i.e. changes in floors dimensions. Its
existence is a requirement for design of this building. The conclusion is that the
presence of greenery on the outside of the building is well used for its spatial
organization.
Presented examples of different position of greenery on the outside of the building
indicate on good design solutions with the aim of the environment conservation.

5. CONCLUSION
The accomplished linkage between architecture and natural environment brings
numerous benefits. Beside the building aesthetic and achieved healthier environment
for living and working, greenery is used as a natural material for construction in most
of presented cases and as a passive technique for cooling and heating, in order to
improve efficient energy use and to decrease the greenhouse-gas emissions, which all
refer to sustainable contemporary design [1]. Related to this, the examples of public
buildings with different greenery positions are analyzed with the aim to determine
their influence on spatial organization. It is concluded that various positions of
greenery do not have negative influence on their spatial organizations. On contrary,
their presence positively affects the spatial organization in regard to the separation of
different functions and connection of the similar ones.
Green areas which are directly or indirectly connected to the building are
sometimes a requirement and sometimes a result of design. Their position should be
used in the best possible way due to spatial organization of a building, and that is
proven by the analyzed examples.

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REFERENCES
[1] Bayer, R. 2008. Green museums and Green exhibits – communicating
sustainability through content and design, Master project, University of Oregon.
[2] Johnston, J. and Newton, J. 2004. Building Green: A guide to using plants on
roofs, walls and pavements. Greater London Authority.
[3] Narkhede, P.G. 2009. Importance og the Terrace Gardens in growing Urban
Areas, Architecture – Time, Space and People. pp. 18-25.
[4] Neufert, E. 2002. Architects’ Data. 37th Edition. Gradjevinska knjiga.
[5] Stamenkovic, M. And Vuckovic, G. 2011. Environmental Aspects of Formation
of Green Roofs in Urban Areas, Proceedings of the ECOS 2011 – 24th
International Conference on Efficiency, Cost, Optimization, Simulation and
Environmental Impact of Energy Systems. Faculty of Mechanical Engineering,
University of Nis. pp. 1966-1971.
Web sources:
[6] Basulto, D. 2009. National Library in Astana, Kazakhstan / BIG, ArchDaily.
Available at: http://www.archdaily.com/33238/national-library-in-astana-
kazakhstan-big/ (Accessed September 2015.)
[7] Hart, S. 2011. Ken Yeang’s National Library of Singapore. ArchitectureWeek.
(533). Available at:
http://www.architectureweek.com/2011/0921/environment_1-1.html (Accessed
September 2015.)
[8] Jordana, S. 2010. Culture Forest / Unsangdong Architects. ArchDaily. Available
at: http://www.archdaily.com/82417/culture-forest-unsangdong-architects/
(Accessed September 2015.)
[9] Lane, T. 2005. A chiling tale. Magazine Features. (29). Available at:
http://www.building.co.uk/a-chilling-tale/3054081.article (Accessed September
2015.)
[10] Meinhold, B. 2011. HWKN’s Artscape is a Green-Roofed Museum That
Emerges From The Ground for Taipei. Inhabitat. Availabe at:
http://inhabitat.com/hwkns-artscape-is-a-green-roofed-museum-that-emerges-
from-the-ground-for-taipei/ (Accessed September 2015.)
[11] Phrawong, X. 2012. Urban Green Mountain. Available at:
http://www.creativemove.com/architecture/urban-green-mountain/ (Accessed
September 2015.)
[12] BIG / National Library in Astana, Kazakhstan. Architectural. Availabe at:
http://www.arthitectural.com/big-national-library-in-astana-kazakhstan/
(Accessed September 2015.)
[13] Green Architecture – The Acros Fukuoka Building of Japan. 2012. Travellers
Bazaar.

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Available at: http://www.travellersbazaar.com/green-architecture-the-acros-

fukuoka-building-of-japan.html#.VC66KW04I5Y (Accessed September 2015.)
[14] 7 awsome rooftop gardens. 2012. St1le. Availabe at:
http://st1le.wordpress.com/2012/03/28/7-awesome-rooftop-gardens/ (Accessed
September 2015.)
[15] http://www.utahprojects.info/Project/Details/116/Logan-Library (Accessed
September 2015.)
[16] http://library.loganutah.org/newlibrary/level1.cfm (Accessed September 2015.)
[17] http://newnation.sg/wp-content/uploads/national-library-singapore.jpg (Accessed
September 2015.)
[18] http://www.designdaily.us/2012/12/culture-forest-unsangdong-architects.html
(Accessed September 2015.)

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
Marina CAREVIĆ

URBANITY AND MIXED USES OF CONTEMPORARY CITIES

Abstract: The issue of this paper is the correlation between urbanity and mixed use. Considering that
these two phenomena are rooted in the same principles, they are presented both individually and through
analysis of mutual relations. Taking into account the complexity of urban systems, the starting point in
the research is based on an understanding of urbanity as a quality that is based on the interaction of
various urban elements, not only physical. The same opinion is also about mixed-use phenomenon,
which is considered a quality if there is an interaction and synergy between uses, and especially among
people who utilize them. The aim of the paper is to explain the notion of urbanity in a broader sense and
to stress the significance of mixing uses to achieve it.

Кey words: Urbanity, mixed use, complexity, urban planning.

URBANITET I MEŠOVITE NAMENE SAVREMENIH GRADOVA

Rezime: Rad se bavi odnosom izmeĊu urbaniteta i mešovite namene. Smatrajući da poĉivaju na istim
principima, ova dva fenomena prikazana su i pojedinaĉno i kroz analizu meĊusobnih relacija. Uzimajući
u obzir složenost gradskih sistema, polazište u istraživanju bazirano je na razumevanju urbaniteta kao
kvaliteta koji se zasniva na interakciji razliĉitih urbanih elemenata, ne samo fiziĉkih. Isti stav zauzima se
i prema konceptu mešovitih namena, koji se smatra kvalitetom ukoliko meĊu tim namenama, odnosno
meĊu ljudima koji ih koriste postoji interakcija koja doprinosi stvaranju većih vrednosti. Cilj rada je da
se pojam urbaniteta razmotri u širem smislu, kao i da se ukaže na znaĉaj ukljuĉivanja mešovitih namena
za postizanje urbaniteta.

Ključne reči: urbanitet, mešovita namena, složenost, urbanistiĉko planiranje.

d.i.a. – Master, Teaching Assistant, Department of Architecture and Urban Planning, Faculty of Technical Sciences,
University of Novi Sad, Trg Dositeja Obradovića 6, Novi Sad, marinac@uns.ac.rs

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1. INTRODUCTION
The complexity, as one of the essential characteristics of contemporary cities, is
becoming more explicit, which inevitably affects the change in understanding of the
notion of urbanity. This complexity implies the existence of many different
components in the urban environment among which relations are created and
multiplied, forming thereby dynamic systems of interconnected elements. As one of
the implications of this multitude, there is also a plenty of city uses, which are with
respect to modern tendencies of sustainable urban development combined within the
same areas following the example of the traditional densely built cities and in contrast
to the modernist dispersed and functionally zoned city.
A review of the literature gives the impression that the issue of the relationship
between urbanity and mixed use is rarely studied, and is therefore the subject of this
paper. Considering that these two phenomena are rooted in the same principles, they
are presented both individually and through analysis of mutual relations. Taking into
account the complexity of urban systems and a multitude of attributes ascribed to it,
the starting point in the research is based on understanding of urbanity as a quality
that is based on interaction of various urban issues, not only physical. The same
opinion is also about mixed-use phenomenon, which is considered a quality if there is
an interaction and synergy between those uses, and especially among people who
utilize them increasing activity and contributing to the creation of greater value.
The aim of this paper is to explain the notion of urbanity in a broader sense and to
emphasize the significance of mixing uses to achieve the urbanity. This combination
of uses should not predefine all functions, but enable development of informal
activities and open possibilities for new connections and interactions.

2. URBANITY
The notion of urbanity is often interpreted in various ways. In the broadest sense
of the term, it could be explained as the state of being urbane, which, according to the
Merriam-Webster dictionary, refers to polite, confident and fashionable (Merriam-
Webster, 2015). Even in the narrower sense, in the urban theory, urbanity is defined
differently. In books of Ranko Radović, there are several variations of explanations.
He quoted the definition of Spreiregen that "urbanity is the quality of good relations
among buildings which enables parts of the physical structure to remain connected to
each other by building the spatial values, which are greater in its entirety, than the
value of each structure taken individually" (Spreiregen, 1965 cited in Radović, 2005).
Radović also presents his vision of urbanity by which it is "a harmonious relationship
between buildings in an urban environment, kind of consensus between the houses."
Although further he explains that the relationship between certain physical structures
can be established according to the content, height, origin and historical values, place
in space, visual relationships, etc., the emphasis is still on the buildings i.e. on the
morphological aspect of the city, which cannot be considered as the only one.

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Similarly, for Louis Kahn, urbanity is a system that is based on an agreement among
the elements of the urban landscape. Reba defines urbanity as the conceived and
sensitive response to surrounding impacts, where those impacts consider all the forces
that shape the form and function of urban space (Reba, 2010). Although this approach
is wider in its understanding (includes all forces, as well as form and function) it
seems that notion "conceived and sensible response" refers only to new interventions
in space, so it could be characterized more as a strategy for urbanity achieving, rather
than definition. In this context, we could also mention Stonor's opinion that urbanity
is the product of urbanism, derived from the synthesis of social, economic and
environmental factors. He also adds that a key challenge of urban design is that its
practitioners successfully orchestrate diverse professional inputs - space/form issues,
transportation issues, land use issues (Stonor, 2006).
Reba and Stonor in a certain way recommend redefining of the term urbanity,
reminding that the urban environment is much more than physical appearance, and
that therefore urbanity itself should involve a much deeper meaning. According to
Montgomery urbanity is "urban quality" - "principle of good city form, activity, street
life and urban culture" (Montgomery, 1998). Without human activity and culture, the
city would be just an aggregate of built structures, so these terms cannot be omitted
from thinking about urbanity. Jean Nouvel also considers culture as one of the main
media between man and the city, noting that urbanity implies harmonious form of
urban intervention, seeking to place people in relationship to the city through culture
and the "genius loci" (Nouvel, 1980 cited in Elin, 2002).
Finally, we should mention the view of Saskia Sassen, similar to Spreiregen, but
more general. Sassen does not emphasize the physicality of urban element, and that is
why such understanding is the most relevant for this work. In her opinion, multiple
elements come together in the context of an urban aggregate and produce something
that is more than the sum of its individual parts (Sassen, 2008). Such opinion gives
the support to think about urban elements not only as built parts of physical structures
but also as immaterial - program, social, cultural, economic etc. Opposed to this, as
she says traditional and Western perceptions, Sassen sets a new term – "cityness".
"Cityness" is a concept that encompasses innumerable types of urbanity, including,
indeed, an intersection of differences that actually produces something new - weather
good or bad, this intersection is consequential (Sassen, 2008). To illustrate this Sassen
mentioned the example of Manhattan where the visual experience of neutral
architecture is conjoined by the experience of the smell of food coming from
immigrant vendors, creating new perspective.
Summing up all above mentioned, it could be said that urbanity is a quality based
on the interaction of various urban components, whether material or immaterial.
Taking into account some Batty's (Batty, 2011) studies of cities and basic
mathematical laws by which the number of connection between the elements is
greater than the number of elements, it is clear why this quality is greater than the
sum of the individual elements. Exactly at this synergetic effect, the concept of mixed

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use is based on, which gives the reason to assume that it contributes to the creation of
urbanity, as an important factor.

3. MIXED USE
In the modern sense, the concept of mixing urban uses was firstly considered in
the sixties of the twentieth century, when the consequences of the construction of
strictly zoned, so-called functional cities were perceived. One of the main goals of
mixing uses in cities is to achieve diversity and vitality by providing the intensity of
activities.
Jane Jacobs was among the first theorists who criticized mono-functional use of
the land, emphasizing that the key condition for generating exuberant urban diversity
is that the districts must serve more than one primary function; preferably more than
two. Primary activities considered are for instance working or living, while the
purpose of the secondary uses is to service the main uses. According to Jacobs, this
must ensure the presence of people who go outdoors on different schedules and are in
the place for different purposes, but who are able to use many facilities in common
(Jacobs, 2011).
3.1. Mixed-use and contemporary age
If Jane Jacobs showed that mixing uses is the essence of urban culture and
economy, then Koolhaas, whose projects represent a radical combination of urban
functions, brought this diversity to the limit, considering that culture must necessarily
be "overloaded" with diversity. He explores how to realize a greater number of
programs with less money, believing that what the building makes exciting is exactly
the complexity of the uses (Dženks, 2007). Koolhaas further points out that
architecture, aesthetically made, and which does not take into account "the great
problems of our time," is losing its credibility and becomes dysfunctional to the
"inevitable paradigm - the universe of systematic supersaturation and malnutrition at
the same time" (Koolhaas, 1998). The culture of supersaturation can be linked to the
phenomenon of excess, which Augé uses to determine the state of supermodernity1 in
the broad anthropological sense, where spatial overabundance is seen as one of the
figures of this excess. Spatial overabundance "is expressed in changes of scale, in the
proliferation of imaged and imaginary references, and in the spectacular acceleration
of means of transport. Its concrete outcome involves considerable physical
modifications: urban concentrations, movements of population and the multiplication
of what is called non-places2" (Augé, 1995). The abundance of diversity, Florida sees

1
According to Augé, supermodernity is a phenomenon which stems from the three figures of excess:
overabundance of events, spatial overabundance and the individualization of references (Augé, 1995)
2
For Augé the word non-place "designates two complementary but distinct realities: spaces formed
in relation to certain ends (transport, transit, commerce, leisure) and the relations that individuals have
with these spaces". He also defines it as a negative of the notion of antropological place, i.e. "spaces in
which neither identity, nor relations, nor history really make any sense" (Auge, 1995)

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not only as a consequence of modern society, but also as a basic need of people,
especially young and creative members of so-called creative class, who look for
plenty of high-quality experiences, an openness to diversity of all kinds, and above all
else the opportunity to validate their identities as creative people (Florida, 2005).
Diversity takes an important place in the work of Sassen, too. She claims that the key
challenge of our time is the recovering of places in the context of globalization,
telecommunication and the proliferation of transnational and translocal dynamics.
"Recovering place means recovering the multiplicity of the presence in this
landscape" (Sassen, 2007). The large city of today has emerged as a strategic site for a
range of new types of operations - political, economic, cultural and subjective - places
where major macro social trends localize and materialize.
Accepting the superabundance as social reality, one might say that
superabundance of urban land uses is the part of it. However, in order to make this
multitude the quality, to make the whole become more important than the sum of its
parts, it is necessary that there are interactions among these parts. When it is spoken
of uses, that means that they must be integrated and organized so that they support
each other, which in spatial terms means that they are within walking distance,
accompanied with the proper built and residential densities, which would provide a
critical mass of users. MVRDV studio believes that the "lava" of programme obtains
its coherence simply through its difference (Maas, 1996), and confirmation of this is
reflected in the existence of a multitude of users. If continuous and intensive presence
of human activities in space is provided, it could be said that the multifunctionality is
at satisfactory level.
3.2. The diversity of uses and uniformity of urban landscape
In 1967, Guy Debord noted that with the beginning of industrialization, the same
architecture appears everywhere, even in the most backward countries in this regard,
as a key prerequisite for the development of a new type of social life (Debord, 2006).
Furthermore, Sassen asserts that homogenization of the urban landscape is the
implication of the contemporary process of urbanization and globalization, but notes
also that this visual uniformity doesn’t bring necessarily unification of economic
processes that are taking place in the certain area (Sassen, 2010). The presence of
people in public spaces that are there because of the various programs existing in the
area, also contribute to visual experience. Winy Maas similarly points out that, in
architectural terms, places around the world are not so prone to homogeneity as
critical regionalists would have us fear. For Maas, places are manifestly different
because of the basic data that lies behind their main formal qualities (Weller, 2001),
since they are manifestation of various processes influenced by local context - social,
economical, political, cultural, historic etc. - different in any given place. Regarding
this, Tilman believes that the most pressing problem is not one of "image quality", but
relates to programmatic givens of an economic and socio nature. Furthermore, he
adds that the design that fixes beforehand all functions and the structures to house
them is absurd - it would fail to plug into the new life-rhythm of the metropolis
(Tilman, 1997). Sassen as well, confirms the importance of informal activities,

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assuming them to be one of the indicators of "cityness". She also states that this type
of "cityness" can be established, even in areas that cannot be said to have urbanity
(understood only as the relationship between the physical structure) (Sassen, 2008).
Uniform urban landscapes can hardly be described as spaces of urbanity, but if mixed
use adds the activity to them, the perception is changed.

4. URBANITY AND MIXED USES

Without denying the role of architectural expression, which not only creates an
image but also conveys meaning and form identity - all of which undoubtedly affects
the urbanity, Montgomery emphasizes that without activity there is no urbanity. In
this regard, the essential condition for achieving urbanity is to generate enough
diversity - the mixture of uses (Montgomery, 1998). This diversity, accompanied with
appropriate densities, should enable activities by stimulation of contacts among
people, therefore through interactions, which are already specified as key
characteristic of urbanity.
The thesis of mixed use as a generator of urbanity, was one of the topics of the
work of Dutch architect Hoek who explored the city of Amsterdam, and showed that
those districts where residential to non-residential gross floor area ratio is about the
same creates an atmosphere of urbanity (Hoek, 2009). This relationship is usually
existent in the central city districts, while the mono-functional zones (whether
predominantly residential or non-residential) are mainly positioned in the periphery.
Through analysis of literature, Hoek has confirmed that the assumption on the impact
of diversity of the uses on urbanity is valid in other cities as well (e.g. in Barcelona).
Mixed-use urbanity can be seen as the urban patina after numerous steps of
transformation and redevelopment, resulting in richness and diversity (Hoek, 2009).
Nevertheless, the question arose about the new fragments that occur in a short period
of time and how to achieve urbanity within them. When we talk about the
interpolations of individual objects in the existing urban fabric, urbanity can be
accomplished as "a conceived response to the surrounding influences" and integration
into the existing context, however, large urban developments, especially greenfield
investments, requires much more attention. The variety of urban facilities and
environment generally develops over time and reflects the accumulated multiplicity
of individuals and social groups, therefore artificially created diversity, so-called
"instant diversity" (Sennet) achieves the desired quality with certain difficulties.
Large contemporary urban developments are often criticized for functionally
overdeterminated, completely spatially detached, privatized, controlled and regulated
form of space (Majoor, 2006). Critics have referred to these places as "junkspace"
(Koolhaas, 2002) and "non-places" (Augé, 2005), that challenge our common-sense
view of public spaces. At the same time, however, such complexes offer the
possibility for innovative combinations of different uses in order to create new places
of urbanity.

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Taking into account the importance of building new areas for the development of
cities, there is an obvious need for their improvement, not just criticism. Jane Jacobs
believes that residents usually isolate from each other in those areas of the city that
lack with natural randomness of public life (Džejkobs, 2011), therefore formal
planning methods should direct human activity just to encourage happening of
informal and spontaneous processes. The existence of open public space is only the
first requirement for achieving this goal. Attracting people and the development of
secondary diversity should be enabled by the presence of diverse primary uses. The
presence of different people in the same place at the same time will not always lead to
mutual understanding and cohesion, but will potentially contribute to social
interaction and creation of an atmosphere of urbanity. It is especially important that
new mixed-use fragments are not planned as isolated islands but as components that
connect the surrounding urban structure, giving people the ability of comfortable
movement through open spaces and staying in it, as well. After all, when Rowley says
that many of the virtues of mixed-use development, only exist to the extent that they
affect, and are experienced from, the public realm (Rowly, 1996), he in fact stresses
the importance of the unbreakable relationship between city and human activities.

5. CONCLUSION
Considering urbanity in the context of contemporary social circumstances, it can
be concluded that urbanity is a quality based on the interaction of various urban
actors, and particularly important is the relationship between the attributes of different
types - between material and immaterial, built and unbuilt, physical and cultural,
morphological and programming, visual and functional, and especially between
human activities and the city. It must be emphasized that this is about adding a
meaning, and not about replacing - adding one more layer of reality to what is already
understood as urbanity, without exclusion of existing components.
Achieving urbanity is an indicator of good relations among different uses, but
open spaces between them have also undeniable contribution to this. However, the
importance of the existence and design of open public spaces for the establishment of
not only social and cultural relations, but also economic, is insufficiently treated topic
in research as well as in developments of mixed use. Given that the core of social life
in public areas is made by spontaneous activities, it would be important to research
the methodology that would help that variety of planned activities accelerate the
development of unplanned, in order to create urbanity.

ACKNOWLEDGEMENT
The paper was done within the project “Optimisation of architectural and urban
planning and design in function of sustainable development in Serbia”, (TR36042)
funded by the Ministry of Education and Science, Republic of Serbia.

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REFERENCES
[1] Auge, M. (1995). Non-Places. London, New York: Verso.
[2] Batty, M. (2011). Building a Science of Cities. UCL working papers series, 1-14.
[3] Debor, G. (2006). Društvo spektakla. Beograd.
[4] Džejkobs, Dž. (2011). Smrt i život velikih američkih gradova. Novi Sad:
Mediterran Publishing.
[5] Dženks, Ĉ. (2007). Nova paradigma u arhitekturi. Beograd: Orion art.
[6] Elin, N. (2002). Postmoderni urbanizam. Beograd: Orion art.
[7] Florida, R. (2005). Cities and the Creative Class. New York: Routledge.
[8] Hoek, J. v. (2009). The Mixed Use Index (MXI) as Planning Tool for (New)
Towns in the 21st Century. New Towns for the 21st Century; the Planned vs. the
Unplanned City, (pp. 198-207). Almere, The Netherlands.
[9] Kolhas, R. (1998). Šoping i grad. Kultura 97 , 41-55.
[10] Koolhaas, R. (2002). Junkspace. October, Vol. 100, Obsolescence , 175-190.
[11] Maas, W. (1996). Massive pluralism. In J. v. W. Maas, FAX MAX (pp. 615-617).
Rotterdam: 010 Publishers.
[12] Majoor, S. (2006). Conditions for multiple land use in large-scale urban projects.
Journal of Housing and the Built Environment Vol.21, No.1, Springer , 15-32.
[13] Merriam-Webster, http://www.merriam-webster.com/dictionary/urbanity,
accessed 20.09.15
[14] Montgomery, J. (1998). Making a city: Urbanity, vitality and urban design.
Journal Of Urban Design, Vol.3, No.1 , 93.
[15] Radović, R. (2005). Forma grada . Beograd: Orion Art.
[16] Reba, D. (2010). Ulica - element strukture i identiteta. Beograd: Orin art.
[17] Rowly, A. (1996). Mixed-use Development: ambiguous concept, simplistic
analysis and wishful thinking? Planning Practice and Research, Vol.11, No.1,
85-97
[18] Sassen, S. (2007). A Sociology of Globalization. W. W. Norton & Company.
[19] Sassen, S. (2008). Cityness. In I. &. Ruby, Urban Trans Formation (pp. 84-87).
Berlin: Ruby Press.
[20] Sassen, S. (2010). Seeing like a city. In R. Burdett, & D. Sudjic, Endelss city (pp.
276-289). Phaidon Press.
[21] Sennet, R. (n.d.). Quant, The Public Realm. http://www.richardsennett.com/
site/SENN/Templates/General2.aspx?pageid=16, accessed 21.08.2013.
[22] Stonor, T. (2006). The Insecurity of Urbanism. In M. Moor, & J. Rowland,
Urban Design Futures (pp. 76-82). New York: Routledge.
[23] Tilman, H. (1997). When dense, when lite? In FAR MAX (pp. 121-127).
Rotterdam: 010 Publishers.
[24] Weller, R. (2001). Between hermeneutics and datascapes (Part Two). Landscape
Review 7(1), 25-43.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 72.01
1
Stefan ŠKORIĆ
Milena KRKLJEŠ2

RECLAIM OF THE CITY'S BUSTLING PUBLIC LIFE

IN CATHOLIC PORT SQUARE
Abstract: In the course of recent years, there has been noticeable loss of meaningful places for the public
life of a city, resulting in gradual withdrawn of public life from the squares. The Catholic Port has
remained almost the only public space of Novi Sad that meets the stationary parameters that distinguish
open space of the city as the square. The aim of this research is to point out dynamic parameters that
constitute a square as vibrant living space which are as important as the stationary physical parts,
creating an "inner dynamics" in the life of the city. The paper will assess different user groups and
activities, as parameters that establish a square suitable for the active social and cultural life of Novi Sad.

Кey words: social space, dynamic parameters, life of square, public activities, Catholic Port.

POVRATAK DINAMIČNOSTI JAVNOG ŽIVOTA GRADA

NA TRGU KATOLIČKE PORTE
Rezime: Tokom poslednjih godina primetan je gubitak značajnih mesta za javni život jednog grada, što
je rezultiralo i u postepenom povlačenju javnog života sa trgova. Trg Katoličke porte je ostao gotovo
jedini javni prostor u Novom Sadu koji ispunjava stacionarne parametre koji čine jedan otvoreni prostor
grada - trgom. Cilj ovog istraživanja je da ukaže na dinamične parametre koji čine jedan trg živim
prostorom, a koji su jednako važni kao i stacionarni fizički delovi trga, stvarajući „unutrašnju dinamiku“
u životu grada. Rad analizira različite grupe korisnika i aktivnosti, kao parametre koji čine trg pogodnim
za aktivni društveni i kulturni život Novog Sada.

Ključne reči: društveni prostor, dinamični parametri, život trga, javne aktivnosti, Katolička porta.

1
M.Arch., research assistant, University of Novi Sad, Faculty of Technical Sciences, Trg Dositeja Obradovića 6,
Novi Sad, Serbia, 021 485 2462, e – mail: skoricstefan@yahoo.com
2
Ph.D., assistant professor, University of Novi Sad, Faculty of Technical Sciences, Trg Dositeja Obradovića 6, Novi
Sad, Serbia, 021 485 2462, e – mail: milenakrkljes@gmail.com

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1. INTRODUCTION: THE WITHDRAWAL OF PUBLIC LIFE FROM

OPEN PUBLIC SPACES
Shaping of a Novi Sad's identity is based on interlacing of many aspects, among
which architectural and urban elements, such as open public spaces, are prominent
elements that have left a mark in the urban matrix of the city. Existence of public
spaces, both within urban core and in its wider surroundings, has contributed to city's
position and importance in gravitating area. A characteristic urban matrix of the city
is punctured with open public spaces, squares and streets, and concealed micro
environments, all standing out as public spaces intended for bustling public life.
Public spaces of the city are complex frames for activities of modern society, and
it is why they are "a powerful symbol of our complex society" [6]. Recent years have
introduced a new kind of city, the one without a place attached to it - a "non-place
urban realm", that provides the bare functions of a city, while doing away with vital,
formal and social mix that gives cities life, resulting in what is missing in this city is
not a matter of any particular building or place, but the spaces in between [13]. These
"non-places", are spaces created for specific goals (transportation, transit, shopping,
etc.) with certain people's attitude towards such spaces [8].
The complex transformations have left consequences on the public spaces of Novi
Sad, initiating that large number of city's squares has lost original purpose of public
space intended for city's public life. The capitalist city has created the center of
consumption, phenomenon that has "eaten away" available public spaces. Interaction
among citizens in traditional public space has been comprehensively dismissed,
despite that the need of every social being is a need for staying in the open public
spaces of the city. On the other hand, the process of privatization and deregulation of
urban policy have increased exclusivity of public space [9], limiting their utilization
to only a specific groups of people. State, supported by class power, expresses the
claim on the exclusive right to dispose and regulate public space, and the public in
general has no right to public space [3].
Cultural policy has continually recognized the importance of open public spaces'
ambiance with a various happenings taking place there. What makes space public is
often not its preordinated "publicness", rather, it is when some group takes space and
through its actions makes it public [7]. The lifelessness of public space depends on
the quality of the space itself, and whether it is encouraging people to do various
public activities and use public space as a significant part of everyday life. All
dynamic activities taking place on open public spaces may be crucial to the spatial
identity of the city, and contribute to the strengthening of public places renowned by
city's inhabitants and visitors. These premises were examined in the case-study of the
Catholic Port, the square that was transformed by decades of rapid changes and still
remains the key 'stage' of the city's public life. This paper explores various stationary,
and in particular dynamic parameters of Catholic Port, constituting framework for
bustling social and cultural life of the city.

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2. SOCIAL SPACE: COLLECTIVE PRODUCTION OF SPACE

Space, temporality, and social being can be seen as dimensions that together
constitute human existence. Collective creation and production of space establishes
people's need for the right to appropriation of public space and a full use of space. To
be able to reach this, open public spaces need to be appropriated by people and their
public activities. On the contrary side of spaces that are produced and designed within
the control of ruling power and as a result of collaboration between the state, capital
and institutional knowledge, there are social spaces. Social space is lived space,
which is shaped by people and in accordance with the needs of the people during an
extensive period of time.
Lefebvre advises that space has a social dimension when used and changed by
people, explaining "the lived" space as a social space [4], focusing on the social
production of the spaces within which social life takes place. Lefebvre embodies the
social spaces by historical sites in old cities, with the concept of "oeuvre" to name this
collective and social production process [5]. The space is an outcome of a collective
and social production, and the city as a social space, is an art work that has been
produced by societies that have lived in the city, and nonetheless "oeuvre" as a space
is an art work that has been created as a representation that is directly related with the
life of society. Socially produced space is created structure that is comparable with
other social structures that are the result of transformation of the given conditions of
life, in exactly the same way that human history represents a social transformation of
time [11].
In addition to the physical dimension of space perceived by diverse senses, space
also has a mental dimension that can be conceived as a concept, or the representation
shaped in our mind about the physical space. Such space is controlled, planned and
produced as a result of human involvement, and it has taken over everyday life by
means of spatial practices. The right to the city appears initially as "a right of
consumption - a right to consume what the city, and city life, has to offer" [10]. That
advises important role of public space as a stage for city life in order to reclaim the
spaces of everyday life, and on the other hand the risk of thereof loss. The squares
were of the utmost importance to every city, as they played out the larger part of
public life.
Streets, squares, parks and other open spaces of Novi Sad are not able to articulate
its urbanity and cope as the public spaces of the city that can build the city's image of
authenticity. In recent times, public life has gradually withdrawn from the public
spaces of the city, and therefore they have lost their earlier meaning and importance.
Today, public life takes place inside huge shopping malls and enclosed halls,
implying increased alienation of people from the possibilities of unmediated social
interactions between them. Such "pseudo public" places, spaces such as malls,
corporate squares and redeveloped parks have encouraged control-led interaction
more than the advancement of unconstrained social relations.

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3. RECOGNITION PARAMETERS OF CATHOLIC PORT SQUARE

Physical, or stationary parameters of square (the urban disposition, geometry of
space, street inflowing, architectural framework, openness/closeness, etc.) are
creating conditions for introduction of dynamic parameters which are generating
public life of the square. The geometry of the square is closely related to analysis of
proportions of square dimensions, as well as between square itself and the height of
surrounding buildings façades. Camillo Sitte points out that the closed nature of the
square is the only way in which the free space in the middle of the city can truly
become square [15], and to create, in that sense, a scene for public life. Successful
squares often have ingenious variations in scenic settings that they offer to their users
[1], and Catholic Port Square achieves to offer such setting to its visitors.
Catholic Port Square (Figure 1, left) is visually contrasted through its enclosed
concept with neighbouring Liberty Square, which has open space character. Catholic
Port Square presents a more intimate urban space in dense urban core of Novi Sad,
achieved by its closeness, size, architectural framework, and contents of the ground
floors. The squares is enclosed with rich architectural framework including the
Cultural Center of Novi Sad, Vatican Palace building, and The Name of Mary
Church, a three-nave Roman Catholic church forming link with the Liberty Square.
On the south-eastern corner, Katolicka Porta Street is making direct connection with
main pedestrian Zmaj Jovina Street, and from northeast Mite Ruzica Street is
tangentially inflowing from Laze Teleckog Street.

Figure 1 – Urban disposition (left) and present existence of Catholic Port Square (right)

Various ambiental, historical and cultural aspects of a square, all represent an

important points in the presence of the square as "urban stage" for socialization,
public activities and public life in general. The square has been reconstructed in 2007,
when centrally positioned fountain was set as main element of urban furniture,
leaving most of active contents in the open ground floors public, including many
restaurants and coffee bars (Figure 1, right). The rectory building, built in 1808, is
one of the most representative examples of profane architecture in Novi Sad and
Vojvodina. Square has intensely changed between the two world wars, when several
buildings were built, such as four-storey building of eminent engineer, publicist and

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historian Daka Popovic, than a former Roman Catholic crafts school and a three-story
building on the corner of Zmaj Jovina Street [14].
As a result of these transformations Catholic Port Square has lost a part of its
character as an enclosed space, notwithstanding that only enclosed spaces could
provide the users with a sense of well-being, comfort and pleasure, and therefore
could determine the public for such spaces. Explored stationary and physical elements
(including preferable areas for sitting and standing, levels of pedestrian movement,
etc.) will make people to stop or spend time within the open public space. An
arrangement of both stationary parameters and dynamic activities has to be achieved
in order to make open public space lively, successful, and engaged with people.

4. DYNAMIC PARAMETERS GENERATING LIFE OF THE SQUARE

Historically, people were engaged in some kind of necessary activities in the
bustling streets, squares and other open public spaces as an important part of daily
life, regardless whether the quality of the space is provided or not. The present-day
public spaces reveal that most of the people are not using public spaces out of
necessity, but because they want to use the public spaces which offer them valuable
opportunities in present-day society. The optional character of the most public
activities sets demands on the quality of public spaces, causing that people will use
them only if the public spaces are well designed. Analysed stationary parameters,
defining the quality of space itself, are creating conditions for introduction of
dynamic public life into the square. All moving elements in the city, and in particular
the people and their activities, are as important as its stationary elements.
Jan Gehl introduces the different concepts of necessary, optional and social
activities [2]. Necessary activities are activities that have to be done (e.g. going to
school or work, necessary shopping, etc.), and they occur regardless of the quality of
the public space. Optional activities are probable only when weather conditions,
quality of public space, surrounding attractiveness, and all other features are met.
Attractive public space is characterized by a multitude of optional activities, creating
conditions for people to choose to spend time in this public space. Social activities
occur whenever people interact with other people. A respectable lively public space
offers a wide range of necessary and optional activities, and it creates stage for social
activities. On the other hand, people using public space can be placed in five user
groups [12]:
1. Everyday users (people that live and work in the area);
2. Visitors/customers (people that visit the services in the area);
3. Passers-by (pedestrians in transit or passing through the area);
4. Recreational visitors (people that visit the area to use the public space in
relation to recreation, pleasure, exercise, play, etc.);
5. Visitors to events (people that visit the public space because of special events).
User group 1-3 visit public space out of necessity, regardless of actual urban
quality of such space, and user groups 4 and 5 visit a public space only if it offers

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high urban quality of space. If these groups are persistent doing optional activities,
they are the indicators of a lively open public space. Only when the quality criteria of
public space is addressed, and when all user groups and different activities are
probable, public space can be a successful public space of high urban quality.
Novi Sad, especially its center, remained with a large number of open public
spaces and different ambients, through which an active social life can take place. In
that sense, open public space, as a part of the city is moment of inner dynamics of the
city itself. Catholic Port Square has remained the only open public space of Novi Sad
that fulfills stationary parameters enabling it to be perceived as square, and
introducing diverse ongoing activities of citizens (Figures 2 and 3).
Despite necessary activities, various optional and social activities are also taking
place in Catholic Port, distinguishing this square from other open public spaces of the
city. Spatial characteristics of square, specifically its closeness, are offering
opportunities for such demanding activities requiring high quality of space. Physical
boundaries made up of architectural framework are generating enclosed space
suitable for optional activities such are open-air exhibitions (Figure 2, left) or weekly
stickers swapping (Figure 2, right).

Figure 2 – Outdoor exhibition (left) and stickers swapping event on Catholic Port Square
(right)

Relation between the quality of public space generated by its stationary

parameters, and the rate of occurrence of dynamic components (necessary, optional
and social activities) is determining the success and lifeness of an public space.
Quality of open public space does not have a great impact on occurrence of necessary
and social activities. On the other hand, good physical quality of public space is
essential for optional activities, creating public spaces that people will use on their
own will. Catholic Port Square is generating good quality of space with its stationary
parameters, making it almost the only public space of Novi Sad intended for optional
activities, and eventually for social activities. Therefore, presence of people and
dynamic activities in the square is key point in attracting all other people.
High frequency of everyday users of square, visitors or customers of available
contents, or current passers-by, is creating inner dynamics of Catholic port. On the

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other hand, the real indicator of successful public space is presence of recreational
visitors and visitors to specific events. Daily, weekly or annual events, such are
gatherings of young people (Figure 3, left), art/music/film festivals (Figure 3, right),
workshops, etc., altogether attract large number of visitors.

Figure 3 – Evening gathering of youth (left) and the Cinema City International Film Festival
(right)

5. CONCLUSION
Most of Novi Sad's squares have lost their original purpose of open spaces
intended for public, resulting in withdrawal of public life. Physical or stationary
parameters of Catholic Port Square, in particular its closeness, should be utilized in
order to create conditions for introduction of dynamic parameters generating public
life of the square. Catholic Port Square has not been used in its full capacity, and
therefore has not yet reached its full potential as open public space of the city.
Experience of dynamic character is crucial for the quality of open public spaces,
which enables spontaneous life of the squares and empowers them to reach their
potential as squares. Dynamic parameters are important as the indicators of a
prosperous and lively public space, reclaiming one square to the citizens. Finding an
appropriate manner in which to emphasize unique spatial characteristics and
potentials of Catholic Port Square could affect cultural policies and preserve such
historically significant space intended for city's bustling public life.
Interrelation between stationary elements constituting square and its urban quality,
various types of activities and different user groups, all mutually determine the
success and lifeness of a public space. If the public spaces are places of encounter and
exchange, well designed and enabling the extensive usage, people will use them,
while the other public spaces will only be used for passing through. Only when the
stationary quality parameters of the square are addressed, and when all user groups
and the different activities are probable, square can be consider as an authentic public
space of the city.

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ACKNOWLEDGEMENTS
The paper was done within the project 'Optimization of architectural and urban
planning and design in function of sustainable development in Serbia' (TR36042),
funded by the Ministry of Education, Science and Technological Development.

REFERENCES
[1] Džejkobs, Dž. 2011. Smrt i život velikih američkih gradova. Novi Sad:
Mediterran Publishing, p. 120
[2] Gehl, J. 2011. Life Between Buildings: Using Public Space. London: Island
Press, p. 9
[3] Harvi, D. 2012. Pobunjeni gradovi: Od prava na grad do urbane revolucije. Novi
Sad: Mediterran publishing, p. 219
[4] Lefebvre, H. 1991. The Production of Space. Oxford: Blackwell, p. 362
[5] Lefebvre, H. 1996. Writings on Cities (eds. Kofman, E. and Lebas, E.). Oxford:
Blackwell Publishers Ltd, p. 169
[6] Lynch, K. 1960. The Image of the City. Cambridge, Massachusetts: The MIT
Press, p. 5
[7] Mitchell, D. 2014. The Right to the city: social justice and the fight for public
space. New York: Guilford Press, p. 35
[8] Ože, M. 2005. Nemesta: uvod u antropologiju nadmodernosti. Beograd:
Biblioteka XX vek, p. 89
[9] Petrović, M. 2009. Transformacija gradova: ka depolitizaciji urbanog pitanja.
Beograd: Institut za sociološka istraživanja Filozofskog fakulteta, p. 109
[10] Schmid, C. 2012. Henri Lefebvre, the Right to the City, and the New
Metropolitan Mainstream. In Cities for people, not for profit – Critical urban
theory and the right to the city (ed. Brenner, N.). London: Routledge, p. 36
[11] Sodža, E. 2013. Postmoderne geografije: Reafirmacija prostora u kritičkoj
socijalnoj teoriji. Beograd: Centar za medije i komunikacije, p. 111
[12] Søholt, H. 2004. Life, spaces and buildings – turning the traditional planning
process upside down. Paper presented to Walk21-V Cities for People, The Fifth
International Conference on Walking in the 21st Century, June 9-11 2004,
Copenhagen, Denmark, p. 4
[13] Sorkin, M. 1992. Introduction: Variations on a Theme Park. In Variations on a
Theme Park: the New American City and the End of Public Space (ed. Michael
Sorkin). New York: Hill and Wang, p. xii
[14] Tepavčević, B. 2008. Trgovi u Vojvodini: morfogeneza, fizička struktura i
funkcije. Novi Sad: Fakultet tehničkih nauka, p. 97
[15] Zite, K. 2006. Umetničko oblikovanje gradova. Beograd: Građevinska knjiga,
p. 61

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SUSTAINABLE DEVELOPMENT AND ENERGY
EFFICIENCY IN CONSTRUCTION
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Ţeljko JAKŠIĆ
Norbert HARMATI2
Milan TRIVUNIĆ3

AN ANALYSIS OF DAMP PRESENCE IN THE SPECIFIC

STRUCTURES OF “DEMIT” FAÇADES
Abstract: In last decade in the bigger cities of Serbia, usage of the expanded polystyrene within the
reconstruction of existing facades with purpose to improve their energy performances as well as overall
esthetic value, better known as “Demit” façade, happens frequently. Such finishing façade walls are
economical and efficient, and therefore commonly used at finishing new buildings. From the long period
of using “Demit” façade has been known that inside of these facades in specific circumstances on edge
between walls and Styrofoam plate some amount of moisture has appears due to condensation of vapor.
This article deals with analyzing cases of the often used structures of facade walls and offers some
solutions that eliminate this phenomenon.

Кey words: Energy efficiency, façade walls, condensation, expanded polystyrene.

ANALIZA PRISUSTVA KONDENZOVANE VODENE PARE U

SPECIFIČNIM KONSTRUKCIJAMA “DEMIT” FASADA
Rezime: U poslednjoj dekadi je u većim gradovima u Srbiji učestala primena ekspandiranog polistirena
(stiropora) u postupku rekonstrukcije postojećih fasada u cilju poboljšanje njihovih energetskih
performansi, kao i opšte estetike, tzv. “Demit” fasade. Ovakva završna obrada fasadnih zidova je, zbog
svoje ekonomičnosti i delotvornosti, učestala i na objektima novogradnje. Iz ranijeg perioda je poznato
da se u ovim fasadama u određenim okolnostima pojavljuje vlaga na spoju konstrukcije zida i izolacije,
kao posledica kondenzovane vodene pare. U ovom radu su analizirani slučajevi konstrukcije najčešće
primenjivanih fasadnih zidova i predloţena rešenja kojima će se eliminisati ova pojava.

Ključne reči: Energetska efikasnost, fasadni zidovi, kondenzacija, ekspandirani polistiren.

1
PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,
e-mail: alt96@uns.ac.rs
2
PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,
e-mail: harmati@uns.ac.rs
3 PhD, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,

e-mail: trule@uns.ac.rs

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1. INTRODUCTION
In comparison with the economic and technological developed countries, Serbia
has seriously focused toward preservation of the energy resources. Among other
things, this is being reflected throughout the characteristic of façade’s structure, both
new buildings and at existing ons. As the most economic suitable styrofoam is in
traffic use, although not the best.
Previous experience in practice indicates that the economy is equal with both price
and working duration. This material has proven to be very practical in cases of
regenerating the facade surfaces whose reparation is complex (requires long work
time and serious financial resources, e.g. at RCC prefabricated façade panels.)
Long term usage of Styrofoam within a structure of facade wall allows more
detailed insight in both the advantages and disadvantages of this procedure. The basic
shortage is the moisture that appears in the contact between two surfaces – structure
of the wall and plate of styrofoam, no matter if or not facade wall satisfies thermal
requests.
For the purposes of this article, using the method of calculation, the structures of
most frequently used facades with integrated Styrofoam were determined, as well as
the ones in cases facade rehabilitation of existing facilities. The results should
indicate weaknesses of the established contents and order of layers at facade wall with
heterogeneous structure. Based on these results a discussion has been done that
enabled adoption of suitable solutions in which have been stopped appear of moisture
within a facade wall. The study was conducted in accordance with the valid national
regulations for energy efficiency.
In this article all calculations have been performed by program „URSA – the
physics for civil engineering 2“ which is adapted to the Serbian regulations for energy
efficiency.

2. FAÇADE ANALYSIS
2.1. Types of facade structures
"Demit" fasade is an expression that represents the specific content of façade walls
layers. In Serbia, „Demit“ facade is widespread as a form of thermally secured walls
for a long time.
"Demit" facade is applied for several affirmative reasons compared with other
existing facades on site (in-situ):
 Satisfactory duration of manufacturing facade;
 Satisfactory quality of the facade, as well as a relatively simple and
economically acceptable remediation of damage;
 Low weight of the material for thermal insulation and façade layer generally;
 Good quality of thermal insulation;
 Good quality of acoustic protection;
 Durability.

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The changes within content of facade structure occurred in that period was not
regarding structure layers changes, but implemented material manufacture technology
inside facades layers. These changes are surely positive.
Diversity in case of "demit" fasade are reflected in the basic structure of facade
element and both the mechanical characteristics of applied Styrofoam (density) and
Styrofoam layer thickness. In the case of primary structure of facade, there are two
categories:
 within new facilities, and
 within existing facilities.
In accordance with the article's theme, the moisture presence in facade wall
structure will be calculated as a function of thickness of the insulation layer made of
Styrofoam. Based on the previous experiences by the calculation has been proven
that the existing moisture in facade wall in the border zone between the wall and
thermal plates are in direct proportion to the insulation thickness – if the layer is
thicker that is less likely to moisture occurs.

2.1.1. Facade walls at the new facilities

Within new facilities as basic structure is being used clay products (bricks normal
format and blocks) or the silicate elements (Ytong), Fig.1.

a) b)
1. Finish (mortal) ... 2cm
2. Masonry – a) ceramic block and b) Ytong ... 25cm
A. Adhesive
3. Styrofoam ... 8-12cm – it varies depending on the structure of the wall
4. Adhesive + glass fibre mesh + adhesive + facade plaster ... approximately
1,5cm

Figure 1 – Styrofoam as an element of thermal protecting for façade walls made of clay
products (blocks or bricks)

For the purpose of calculation three solutions of facade wall will be in use, which
vary only within the thermal insulation thickness (Fig. 1, item 3). These variants will

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be used for three cases of manufacturing of the basic wall structure made of masonry:
brick, clay block and Ytong block.
Table 1 presents an overview of selected facade structures, with remark that the
layers of thermal insulation were installed with thicknesses which are necessary to
satisfy their energy efficiency requests.
Таble 1- Three types of facade walls insulated by plates of Styrofoam
Sketch of façade wall structure Temperature distribution Diagram of vapor diffusion

A
R=3,469m2K/W
Uc=0,288W/m2K
Basic structure made of brick Umax=0,300 W/m2K

B
R=3,381m2K/W
Uc=0,296W/m2K
Basic structure made of clay block Umax=0,300 W/m2K

C
R=3,366m2K/W
Uc=0,297W/m2K
Basic structure made of Ytong Umax=0,300 W/m2K

2.1.2. Facade walls at the existing facilities

Within existing facilities the both side plastered wall has been used as basic
structure of facade which is made of different kinds of clay products (different types
of bricks or blocks) and prefabricated reinforced concrete panels, Table. 2 and 3.
The new Regulation treats the structure of existing façade wall as a different
structure in regards to the new wall. The allowed value of coefficient Umax (0,400
W/m2K) is a little bit higher than at the existing Umax in the new Regulation (0,300
W/m2K)

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Таble 2- A type of existing facade wall: A) non insulated; B) insulated
Sketch of façade wall structure Temperature distribution Diagram of vapor diffusion

A
R=0,698m2K/W
Uc=1,433W/m2K
Basic structure made of brick Umax=0,400 W/m2K

B
R=3,398m2K/W
Uc=0,294W/m2K
Basic structure made of brick
Umax=0,400 W/m2K
reinforced by Styrofoam

Таble 3- A type of existing facade wall made of RCC: A) non insulated; B) insulated
Sketch of façade wall structure Temperature distribution Diagram of vapor diffusion

A
R=2,741m2K/W
Basic structure made of brick Uc=0,365W/m2K
Umax=0,400 W/m2K

B
R=3,490m2K/W
Uc=0,287W/m2K
Basic structure made of brick Umax=0,400 W/m2K
reinforced by Styrofoam

3. DISCUSION
The Regulation for energy efficiency treats a facility as a building that dissipates
energy. The first crucial change refers to the design temperatures at winter which are
higher at some cities in comparison with previous Regulation and in a same time
according to the new climate conditions. Based on external design temperature a
division on zones has been done to determine the temperature of external air in case

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of the vapor calculations in a structure at the heating time and a duration drying of the
structure in case of the condensation.

Таble 4- Cross section throughout the tie (ring) beam or lintel made of RCC:
A) non insulated; B) insulated
Sketch of façade wall structure Temperature distribution Diagram of vapor diffusion

A
R=0, 337m2K/W
Uc=2,965W/m2K
Basic structure made of RCC Umax=0,400 W/m2K

B
R=1, 112m2K/W
Uc=0,899W/m2K
Basic structure made of RCC Umax=0,400 W/m2K

The article researches a presence of vapor inside the layers of façade walls, which
was created as effect of the water vapor diffusion, for an average level of moisture of
55%. Increasing temperature of the outside air to calculate diffusion within the
Regulation, reveals the following facts:
 Within a new build facades wall made of clay elements and thermal insulated
by Styrofoam plates there is no condensation (Table 1);
 Within an existing façade wall made of clay elements, on both side plastered
(Table 2. A) without thermal insulation there is neither condensation nor dew;
 Within an existing façade wall made of clay elements additionally insulated by
Styrofoam plates with thickness a=3cm it's possible ensure a minimum value
of Uc. No condensation occurs (Table 2. B);
 At existing reinforced concrete insulated wall panels some amount of
condensation are obvious;
 At existing reinforced concrete sandwich panels by adding insulation layer
thickness of at least а=3 cm prevents the occurrence of condensation in the
construction. A thinner layer of Styrofoam (e.g. a = 2 cm) could not prevent
this phenomenon;
 Changing the thickness of thermal insulation or percentage of the humidity
does not affect the appearance of condensation in the structure of façade wall,
while the density of the final layer does it. If the material density increases, the
quantity of condensate increases, too.

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4. COMMENTS AND SUGGESTIONS

Appearing condensation inside the layers of facade wall is a phenomenon that can
be proved by calculation. According to the new Regulation about energy efficiency
within the cases of analized facade walls only inside of the precast RCC panel occurs
the condensation (about 17 days drying).
Increasing the finishing layer thickness of panel (fig.2 tout=8cm) the quantity of
condensate grows, too as well as increase of the drying days. At the other types of
façade walls made of bricks or clay blocks or Ytong blocks, at some unusual
circumstances (e.g. changes of the indoor air humidity or significantly lower external
temperature), may reach to an unsatisfied value of overall coefficient Uc or dew but
not the condensation.
Based on the previous observations, we can conclude that the condition and
appearance of condensation in the façade structure which is insulated by the
Styrofoam affects the processing of finalisation of outer layer – by its own density
and thickness.
By applying the new Regulation can be seen that it is enough to put an insulating
layer by thickness of d = 3cm to prevent the occurrence of condensation in inside of
RCC walls. For the other types of facade walls (brick, block, Ytong) dew does not
occur even when there haven't been insulated (Table 2 and 3).
Precast RCC panel (Table 3) is the only facade wall among the analized walls in
the article at which condensation appears where it notes that the drying takes more
than 17 days. By adding a layer of Styrofoam minimum thickness d = 3cm eliminates
the possibility of condensation in the wall structure.

5. CONCLUSION
It’s generally known that condensation in the structure of building presents a
double dangerous: a) minimize a thermal insulation efficiency and b) damaging the
same one. By using a method of calculation, within the new Regulation about energy
efficiency, in the article have been analysed the cases of the condensation occurrence
in the external walls with and without insulation of Styrofoam.
The basic idea was to establish and to adopt as a standard for the construction
purposes a content of layers of the most commonly used structures of external walls.
A necessary thickness of thermal insulating layer of Styrofoam to satisfy all necessary
minimal conditions (heat transfer coefficient, diffusion of water vapor, resistance to
dew and thermal stability) has been used for that case. The accent was given on
satisfying of heat transfer coefficient and diffusion of water vapor (and the occurrence
of condensation inside the wall structure). It is also necessary to note that under the
new Regulations for the maximum permissible value of coefficient U is different for
the existing walls and the new ones.
Obtained results was generally expected although it has assumed that condensate
would have occured in the much more situations within the structure of facade wall.
The main conclusion derived from this research is that final layer over the Styrofoam

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must be vapor permeable and low density. The thicker final layer with high density is
a characteristic of the prefabricated RCC panels. In these cases, the appearance of
condensed water can be prevented at old buildings by adding a layer of minimum
thickness of 3 cm , and for new RCC panels can be avoided by adding a vapor barrier
between the inner wall and Styrofoam. Installing plates of Styrofoam as a final layer
upon the RCC panels is the most efficient method for the renewing of old facades
(inexpensive and quick).

ACKNOWLEDGMENT
The work reported in this paper is a part of the investigation within the research
projects III42012 supported by the Ministry for Science and Technology, Republic of
Serbia.

REFERENCES
[1] RAISA, Metod Saje s.p., URSA – the physics for civil engineering 2. Belgrade:
URSA, Belgrade. (in Serbian)
[2] CETRIS8 facade systems, http://www.kalcer.rs/cip_cetris/Katalog%20fasade.pdf,
Review a browser 08.10.2015.
[3] Winterling, H., Sontag, N.(2010). Rigid Polystyrene Foam (EPS,XPS).
Kunststoffe International.10/2011. PE1108pp. 32-37.
[4] Pauter, P., Panovec, J. Energy efficiency project according new and existing
buildings. OAMK – Oula University of Applied Sciences.
http://www.oamk.fi/utils/opendoc.php?aWRfZG9rdW1lbnR0aT0xNDMwNzYx
MDI2. Review a browser 08.10.2015.
[5] TOPIC Moisture Safety – NBS 2014. http://www.nsb2014.se/wordpress/wp-
content/uploads/2014/07/Moisture_Safety.pdf Review a browser 08.10.2015.

[572]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Konstantin KAZAKOV
Ana YANAKIEVA2
Anita HANDRULEVA3
Iliana STOYNOVA4
Vladimir MATUSKI5

ENERGY EFFICIENCY RENOVATION OF OFFICE-BUILDING IN

SOFIA, BULGARIA - CASE STUDY
Abstract: In this paper a comparative analysis of phased energetic renovation of an office building,
situated in the city of Sofia and designed according to the standards for Energy efficiency, forced at the
time was made. Different economic indicators are used. For comparison base modern legislation and
prices of materials for remediation are adopted. The most suitable approach for a such case is shown.
Optimal pricing strategy is formulated.

Кey words: energetic renovation, energy efficiency.

ENERGETSKA OBNOVA POSLOVNE ZGRADE U SOFIJI U

BUGARSKOJ – STUDIJA SLUČAJA
Rezime: U radu je sprovedena komparativna analiza fazne energetske obnove poslovne zgrade, locirane
u Sofiji i projektovane prema standardima za energetsku efikasnost koji su tad bili na snazi. U analizi su
korišćeni različiti ekonomski indikatori. Za komparaciju su izabrane osnove modernog zakonodavstva i
cene materijala za obnovu. Takođe, prikazan je optimalan pristup i formulasane su optimalne cenovne
strategije.

Ključne reči: energetska obnova, energetska efikasnost.

1
USEA “Lyuben Karavelov”, Department “Mechanics and Mathematics”, e-mail: kazakov@vsu.bg
2
Bulgarian Academy of Science, Institute of Mechanichs, e-mail: aniyanakieva@imbm.bas.bg
3
USEA “Lyuben Karavelov”, Department “Mechanics and Mathematics”, e-mail: anita_handruleva@abv.bg
4
USEA “Lyuben Karavelov”,Department “Mechanics and Mathematics”, e-mail:, e-mail: stoynova@vsu.bg
5
USEA “Lyuben Karavelov”, Department “Mechanics and Mathematics”, e-mail: vladimirmatuski@abv.bg

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1. INTRODUCTION
According to EU directives required rate of renovation of buildings is increased, as
the existing building stock is the sector with the greatest potential for energy savings.
The conclusions of the European Council of 2007 stressed the need to increase energy
efficiency in the Union to achieve by 2020, 20% of primary energy consumption in
the Union compared to projections. Moreover, buildings are crucial to achieving the
Union's target to reduce greenhouse gas emissions by 80-95% by 2050 compared to
1990. The implementation of cost-effective energy solutions and the development of
measures to improve energy efficiency the buildings are justified by the benefits and
savings associated with their implementation. [1] In developing measures to improve
energy efficiency should take into account the benefits and savings associated with
efficiencies that are achieved through the widespread application of cost-effective
technological innovations.

2. DESCRIPTION OF THE BUSINESS BUILDING

Concerned business building was built in 1996 and is situated in Sofia. It was
designed and constructed according deystvashtana then regulations and requirements
for the technical efficiency. Then current requirements for the technical efficiency are
quite low in comparison with the requirements placed on energiiyna efficiency at
present. The building has four floors and a basement and attic. Filled Reinforced
concrete roof slab and 10 cm insulation. EPS under the roof covering. Its built area is
221 square meters and the total area of 1603 square meters slack. The construction is
reinforced concrete, skeletal beam, brick external walls are 25 cm thick.

Fig.1. Facades east – north-east and west before implementation of rehabilitation

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3. ENERGY RENOVATION
The building was renovated in stages, according to current regulations. Renovation
of the building was completed in early December 2010. Filled external insulation of 8
cm. EPS (expanded polystirol) in two stages and mineral plaster. In implementing the
first stage is filled insulation just southwest facade and internal insulation of
reinforced concrete diaphragm earthquake of eastern facade. In the second stage is
completed thermal insulation of facades and other bays. Replaced all sills and
removed existing leaks. External brick walls insulation was executed according to the
detail shown in Figure 2. Replacement is compromised insulation on the balconies on
the top floor. In the attic is filled insulation 5 cm. EPS by hand Flatten the ceilings of
the rooms and the walls and ceilings laid insulating latex.

Wall
Adhesive
EPS-Facade heat insulation panel
Adhesive
Glass-fiber mesh
Facade mineral plaster

Fig. 2 Detail the performance of insulation in walls

Fig. 3. Facades east – north-east and west after a refurbishment

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4. COMPARATIVE ANALYSIS OF TECHNICAL-ECONOMIC

INDICATORS
Table 1 shows the technical and economic indicators of the present building.

Tab.1 Technical and economic indicators of the present building.

Built area 221 sq.m.
Built-up area 1603 sq.m.
Area of the walls filled with insulation – I stage 110 sq.m.
Area of the walls filled with insulation – II stage 503 sq.m.
Value of construction works for carrying out energy efficiency measures 11 020 Euro

Fig. 4 and 5 show graphs of average monthly temperatures (Figure 4) during the
heating season of 2009-2014, and electricity consumption (Figure 5) for the same
period.
Typical of these graphics are sharp jumps consumption in 2009-2010 and
significantly smooth increase or decrease in electricity consumption in the period
after 2010 ie after the refurbishment.

16
14
12
10
Temperature, C
o

8
6
4
2
0
-2
-4
-6
Jan Feb Mar Apr Oct Nov Dec
2009 -2 1 6 12 12 8 3
2010 0 2 6 11 10 11 0
2012 -3 -4 6 12 14 8 -1
2013 0 3 6 12 13 8 -4
2014 1 6 9 11 11 7 1
Fig. 4. Average monthly temperatures during the heating season, 2009-2014.

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14000
12000
kWh
kWth 10000
8000
6000
4000
2000
0
Jan Feb Mar Apr Oct Nov Dec
2009 9736 7425 12719 9004 5700 5891 9004
2010 8258 8357 7762 5588 4404 4998 10748
2011 9450 9005 9278 5517 4277 6455 8537
2012 8802 9314 7356 3390 1404 4250 9874
2013 8620 4690 4516 4470 2806 5430 5250
2014 4720 5400 4170 2073 1870 5640 8620

Fig. 5. Consumption of electricity generated for heating, 2009-2014.

Fig. 6 and 7 respectively show graphs of average temperature and average fuel
elekroenergiya for the heating season 2009-2014.
There are approximately the same average temperatures for the heating season of
2009, 2010 and 2013 gradually reduce the cost of electricity generated for heating the
building, such a reduction is 16% for 2010 compared to 2009 and by 40% in 2013
compared to 2009.
8.0
Temperature,

6.0
Temp.

4.0
2.0
0.0
C

2009 2010 2011 2012 2013 2014

o

Series1 5.7 5.7 4 4.6 5.4 6.6

Fig. 6. Average temperatures for heating season.

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9000
8000
7000
6000
5000
kWth
kWh

4000
3000
2000
1000
0
2009 2010 2011 2012 2013 2014
Series1 8497 7159 7503 6341 5112 4642

Fig. 7. Average cost of electricity for heating season.

Tab 2. Movement of electricity prices during the period 2009-2014.

Year 2009 2010 2011 2012 2013,
2014
Jan.- Jan.- July- Jan.- July- Jan.- July- Jan.-
Dec. June Dec. June Dec. June Dec. Dec.
Price, 0.112 0.112 0.118 0.123 0.128 0.128 0.148 0.153
€/kWh

5. BASIC REMARCS
The conclusions are made based on observations of an office building with about
24 units. tenants for seven years: two years ago and renovating five years thereafter.
The building has no central heating and each tenant decides how to be heated in the
autumn and winter months. In this case do not always choose the most efficient
heater. So comparing electricity consumption with the average temperature in the
months and years. The graph shows that after the renovation costs decrease with each
subsequent year. There's a few reasons:
a) The summer temperature of the outer walls of the building is retained longer.
b) Only tempering premises becomes faster and less power consumed. Energy
because the walls are already playing the role of the battery heat.
c) A comfortable working temperature in the rooms.
d) Life of electricity. Heaters shall be extended for a smooth load schedule of
work without spikes.
e) Savings in power. Energy can help to purchase more expensive, but more
efficient heaters with a longer service life and lower power consumption.
f) if we ignore the price increase of current expenditure for rehabilitation in our
case can be compensated for 12 years. But we should be noted that from 2009

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to 2015 the price of electricity has changed from 0.22 l BGN / kWh to 0.30
BGN / kWh or 36%. On the other hand this discipline people and they begin
to use more efficient heating and displayed as graphs consumed el. Energy
decreases while keeping the other components: tempering, comfortable
temperature.

6. CONCLUSION
Taking into account the reduced energy consumption of electrical charges as a
result of the use of energy efficient solutions, such as the remediation costs incurred
will be recouped over a period of 10-12 years. The temperature in the premises of 21 -
23oC is achieved and maintained with significantly less heat loss. Energy efficient
solutions enable optimum use of space heaters, as well as more flexible temperature
control in workplaces both work and overtime. Beyond these financial indicators can
point to progress and greater comfort in the workplace, as well as more rational
operation of heating appliances, thus increasing and their lifetime.

ACKNOWLEDGEMENT
The study has been financially supported by the National Science Fund, Project
DFNI E02/10121214, and USEA(VSU) “Lyuben Karavelov”, Projects 02/2013,
02/2014 and 13/2014.

REFERENCES
[1] Directive 2012/27 / EU of the European Union on energy efficiency
[2] Energy Efficiency Act, Prom. SG. 35 of 05.15.2015, effective from 05.15.2015
[3] Michael Donn et al., Solution Sets for Net Zero Energy Buildings,
Ernst&Sohn,2015,ISBN 978-3 433-03072-1
[4] Ivanova J.,V. Valeva,T. Petrova,W. Becker,A. Yanakieva,Interface delamination
of bi-material structures with different industrial applications in energy
structures, In Proc.: Ist South East Europ. Conf. on Sustainable Develop. of
Energy, Water and Environment Systems, 29 June-3 July, Ohrid, Republic of
Macedonia, Ohrid, (2014)
[5] Aleksiev A., Hrischev L., Solar radiation influence on the temperature change
expanded polysyrene's top surface, 15-th International Conference VSU 2015q
Sofia, Bulgaria.

[579]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Ţeljko KOŠKI
Irena IŠTOKA OTKOVIĆ2
Hrvoje KRSTIĆ3

AIRTIGHTNESS INVESTIGATION OF RESIDENTIAL UNITS

BUILDING ENVELOPE IN CITY OF OSIJEK
Abstract: This paper describes the airtightness investigation process of existing residential units in the
city of Osijek in order to determine their condition and potential for building envelope renovation.
Research presented in this paper was the first of this kind carried out in Croatia. The residential units’
airtightness database is obtained in situ at 58 units in the local area. This paper presents average
airtightness values for non-renovated residential units in each period of construction and procedure of
data processing for forming database needed for neural network learning. Results indicate a trend of
significant improvements in airtightness in the periods of recent construction. The results obtained by
this research were used for prediction of residential units' airtightness by applying neural networks.

Кey words: airtightness; residential units; building envelope

ISPITIVANJE ZRAKOPROPUSNOSTI STAMBENIH ZGRADA NA

PODRUČJU GRADA OSIJEKA
Rezime: U radu je opisan postupak ispitivanja zrakopropusnosti stambenih jedinica na području grada
Osijeka s ciljem utvrđivanja postojećeg stanja i potencijala za obnovu ovojnica zgrada. Istraţivanje
prikazano u radu je prvo takve vrste provedeno u Republici Hrvatskoj. Načinjena je baza podataka o
vrijednostima zrakopropusnosti za 58 stambenih jedinica. U radu su prikazane prosječne vrijednosti
zrakopropusnosti neobnovljenih postojeći stambenih jedinica ovisno o periodu izgradnje kao i postupak
formacije baze podataka koja bi se koristila za učenje neuralnih mreţa. Rezultati su pokazali trend
poboljšanja vrijednosti zrakopropusnosti za novije periode izgradnje. Prikazani rezultati su se koristili za
formiranje modela predikcije zrakopropusnosti uporabom neuralnih mreţa.

Ključne reči: zrakopropusnost; stambene zgrade; ovojnica zgrade

1
Associated professor. Faculty of Civil Engineering Osijek, Crkvena 21, Osijek 31000, Croatia, zkoski@gfos.hr
2
Assistant Professor. Faculty of Civil Engineering Osijek, Crkvena 21, Osijek 31000, Croatia, iirena@gfos.hr
3
Assistant Professor. Faculty of Civil Engineering Osijek, Crkvena 21, Osijek 31000, Croatia, hrvojek@gfos.hr

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

1. INTRODUCTION
The European building sector is responsible for about 40% of the total primary
energy consumption [1]. This great amount of energy is partly wasted because
buildings that were constructed several decades ago do not meet the energy efficiency
requirements according to current legislation in the European Union. Airtightness of
the building helps to avoid uncontrolled airflows through the building envelope,
which can lead to problems related to the hygrothermal performance, health, energy
consumption, performance of the ventilation systems, thermal comfort, noise, and fire
resistance [2]. Airtightness of rooms is a critical factor in buildings and houses,
especially when reducing convective heat losses to a minimum by extended thermal
insulation ventilation becomes the major factor of energy use. Any air change on top
of the necessary volume is a causeless loss [3].
The main scientific target of this research was to gather information on the
airtightness of residential units various construction types, usage and age. A building's
airtightness directly affects its heat losses, so uncontrolled air exchange dramatically
increases heating requirements. Figure 1 shows the relationship between heat losses
[kWh/m2a] and air changes [1/h] in buildings.
Summarized previous research regarding buildings airtightness reveals the
following:
 Airtightness can be affected by design and management concept, design
details, type of structure, method of construction, type of thermal insulation,
the number of storeys, building envelope surface area, floor area, execution
quality of works and supervision of construction, season of the year, climate,
how well the units are maintained, type of unit, joinery, frame materials,
window frame length, total frame length, age of the buildings, number of
significant cracks and management context [2, 4-9] and
 The leakage airflow rate might be evaluated using predictive models
determined from experimental databases [10].

Figure 1 – Relationship between specific heat demand and air changes [11]

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The research presented in this paper was the first of this type in Croatia and it took
place as part of the IPA Cross-border Cooperation Programme between the Republic
of Hungary and the Republic of Croatia under the title “Air tightness investigation of
rooms from the point of view of energy and comfort”, (ID: HUHR/1001/2.1.3/0009),
which was co-financed by the European Union.
This paper highlights the lack of practical research in airtightness for
existing residential buildings in Croatia and develops a comprehensive procedure for
forming airtightness values database. The aim of this paper is to present:
 Formation of database for airtightness measurement,
 Analysis of obtained measurements results and
 Possibility of processing obtained data for forming database needed for neural
network learning.

2. AIRTIGHTNESS MEASUREMENTS IN CROATIA

For the purposes of this study, a database of residential units in the territory of
Osijek-Baranja County has been created. The database contains 58 residential units,
47 of which are from the area of the city of Osijek (81%), while the other 11 are
located in suburban areas (19%). In order to determine the representativeness of the
residential units' database in terms of construction year and share of residential units
according to the construction year in the total number of residential units in the
Republic of Croatia, the following comparison was made and presented in Figure 2.
Figure 2 shows that shares of residential units according to the construction year in
the total number of residential units at project level and at the level of the Republic of
Croatia are analogous.

Figure 2 – Graphical presentation of age comparison between residential units stock from the
database of the Air Tightness Project and the residential units stock of the Republic of Croatia

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Similar comparison was made between the age of residential units at the level of
the European Union (average values from year 2010. without Bulgaria; Source: Age
distribution of housing stock, Housing Statistics in the European Union 2010) and Air
Tightness Project, the results are presented in Figure 3. Figure 3 which show that
shares of residential units according to the construction year in the total number of
residential units at project level and at the level of the EU are somewhat analogous.
The results presented in figures 2 and 3 are important because this research has
tendency for developing a predictive model which could be applied in all EU
countries.

Figure 3 – Graphical presentation of age comparison between residential units stock from the
database of the Air Tightness Project and the average residential units stock in the EU

Before beginning the testing of airtightness in buildings one needs to gather all
necessary data. Required data can be categorized in four basic groups:
 General information on the building
 Information on reconstruction of the building,
 Information on the building envelope and
 Meteorological information.

The method most often used for measuring airtightness is the pressure difference
method (the “blower door” test); application of this method is described in detail in
the HRN EN 13829:2002 standard (Thermal performance of buildings -
Determination of airtightness of buildings - Fan pressurization method).
Measurements were carried out following method A– the condition of the external
building envelope needs to be representative for the season of the year when heating
or cooling systems are used, without additional sealing [12, 13].

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The Air Changes per Hour at 50 Pascals (n50, ACH at 50 Pascals) is commonly
used measure of building airtightness [14]. Measuring of airtightness was conducted
using the device “Minneapolis BlowerDoor”. The device was connected to a
computer via an USB port and an accompanying program called TECTITEExpress
3.6.
Typical air leakage places in the studied residential buildings were same in this
research as described already by other previous researchers such as [2]:
 junction of the ceiling/floor with the external wall;
 junction of the separating walls with the external wall and roof;
 penetrations of the electrical and plumbing installations through the air barrier
systems;
 penetrations of the chimney and ventilation ducts through the air barrier
systems;
 leakage around and through electrical sockets and switches;
 leakage around and through windows and doors.

3. ANALYSIS OF MEASUREMENTS RESULTS

Measured value of airtightness at a pressure difference of 50 Pa (n50) for entire
database of residential units ranged between 0.76 and 19.64 (1/h). Average
airtightness values for non-renovated residential units in individual periods of
construction are presented in Table 1, also visible on the chart in Figure 4.
These results show a trend of significant improvement in airtightness in the
periods of recent construction, which can be expected considering the technical and
technological advancements in construction.

Таble 1- Results of measuring airtightness

Period of Prior to After
1945-65 1966-75 1976-85 1986-95 1996-05
construction 1945 2006
Number of
5 11 13 13 8 4 4
samples
Mean value n50 9,69 8,43 10,87 5,26 3.00 2,32 2,99

Further on, analysis of the thermal quality of windows installed in residential

buildings in the last hundred years reveals a continuous trend of improvement,
especially in the last two decades.

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Figure 4 – (a) Mean value of airtightness (n50) according to periods of construction; (b)
Changes in thermal quality of windows and external walls

The curve in Figure 4a reflects the changes in airtightness of residential units

throughout different periods of construction and it is comparable to the curves in
Figure 4b which are approximation of changes in average quality of thermal
protection of external walls [15] and approximation of improvements in thermal
quality of windows through different construction periods. Average airtightness value
for entire database of non-renovated residential units is 4.90 1/h.
Those average values, minimum and maximum airtightness values and number of
houses together with remarks are compared among different countries according to
data [2] presented in Table 2.

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Таble 2- Comparison of airtightness of detached houses in different countries [2]

Air change rate at
Number 50 Pa, n50 (1/h)
Country, measurement
of Remarks
time Min-
houses Average
max.
Belgium, 1995-98 51 7,8 1,8-25
Canada, 1985-95 222 3,1 0,4-11 New conventional hoses
Estonia, 1999-2000 19 9,6 4,9-32
Estonia, 2003-05 31 4,9 0,7-14 Built in 1993-2004
Common pre-fabricated timber-
Finland, 1979-81 16 6,0 2,2-12
frame wall-element hoses
Finland, 1981-98 171 5,9 1,6-18 Mostly reclamations cases
Finland, 2002-04 100 3,9 0,5-8,9 Timber-frame envelope
Built in 1980, low-energy
Norway, 1984 10 4,0 3,3-5,4
houses
St.dev.
Sweden, 1978 205 3,7 Built in 1982-89
1,24
United Kingdom 471 13,1 -
USA 12902 29,7 0,5-84 Built in 1850-1993
0,76-
Croatia, 2013-14 58 4,9 Built in 1945-2006
19,64

4. CONCLUSION
Measurement results of airtightness in Croatia by using the blower door method
are comparable to the results of measurements obtained in other countries. Obtained
results were used for the purpose of testing the possibilities of using neural network
model for predicting airtightness in residential units. An evaluation system was
created for evaluating input parameters which were found in the course of the study to
have an effect on airtightness results [9]. A noticeable effect on airtightness results
comes from the quality of transparent parts of the residential unit envelope, i.e.
windows, as well as the quality of their installation. An example of this can be given
in the form of measured airtightness values (n50) at two different locations. The same
residential units, following a complete alteration of windows, exhibit significant
reduction in airtightness, from the initial 6.39 (1/h) to 1.13 (1/h) and from 5.73 (1/h)
to 0.94 (1/h). The analysis of measurement results provided the selection of 4 input
parameters of the model: the quality of transparent and opaque parts of residential
unit envelopes, the percentage of transparent parts in the envelope and the percentage
of residential unit envelope which borders with (i.e. is directly exposed to) exterior
space. The neural network model gave a good prediction of airtightness on the
measured database in local condition, correlation coefficient between measured data
and neural network prediction is 95.37%. Validation of the model on new sets of

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measured data will give a fuller insight into the applicability of the model locally as
well as broader.

ACKNOWLEDGEMENTS
Acknowledgement for the EU Hungary-Croatia IPA (Instrument for Pre-
Accession Assistance) Cross-border Co-operation Programme is for funding the
project including equipment procurements and manpower.

REFERENCES
[1] Tommerup, H., J. Rose, and S. Svendsen, Energy-efficient houses built
according to the energy performance requirements introduced in Denmark in
2006. Energy and Buildings, 2007. 39(10): p. 1123-1130.
[2] Kalamees, T., Air tightness and air leakages of new lightweight single-family
detached houses in Estonia. Building and Environment, 2007. 42(6): p. 2369-
2377.
[3] Fülöp, L., et al., Air tightness investigation of rooms from the point of view of
energy and comfort, 2013: Osijek.
[4] Wanyu, R.C., J. Jeffrey, and H.S. Max, Analysis of Air Leakage Measurements
of US Houses. Energy and Buildings, 2013. 66: p. 616–625.
[5] Sinnott, D. and M. Dyer, Air-tightness field data for dwellings in Ireland.
Building and Environment, 2012. 51(0): p. 269-275.
[6] Montoya, M.I., et al., Air leakage in Catalan dwellings: Developing an
airtightness model and leakage airflow predictions. Building and Environment,
2010. 45(6): p. 1458-1469.
[7] Pan, W., Relationships between air-tightness and its influencing factors of post-
2006 new-build dwellings in the UK. Building and Environment, 2010. 45(11):
p. 2387-2399.
[8] Sfakianaki, A., et al., Air tightness measurements of residential houses in
Athens, Greece. Building and Environment, 2008. 43(4): p. 398-405.
[9] Krstić, H., et al., Application of Neural Networks in Predicting Airtightness of
Residential Units. Energy and Buildings, 2014(0).
[10] Iordache, V. and T. Catalina, Acoustic approach for building air permeability
estimation. Building and Environment, 2012. 57(0): p. 18-27.
[11] ISOVER. Energy efficiency - Save money with ISOVER. 2014 [cited 2014
8.11.2014.]; Available from:
http://www.isover-airtightness.com/Benefits/Energy-efficiency.
[12] EN 13829:2002, Thermal performance of buildings -- Determination of air
permeability of buildings -- Fan pressurization method (ISO 9972:1996,
modified; EN 13829:2000), 2002.

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[13] Tehnički propis o racionalnoj uporabi energije i toplinskoj zaštiti u zgradama

(Translation: Technical Regulation on the Rational Use of Energy and Thermal
Insulation in Buildings). „Narodne novine“ broj 97/14, 130/14; Available from:
http://narodne-novine.nn.hr/clanci/sluzbeni/2014_08_97_1938.html.
[14] TECTITE Express Manual Ver 3.6. The Energy Conservatory [cited 2013
15.10.2013.]; Available from:
http://materialy.wb.pb.edu.pl/irenaickiewicz/files/2013/01/TECTITE-Express-
Manual-Ver-3.6.pdf.

[588]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.131.1
1
Milan MARINKOVIĆ
Bojan MATIĆ2
Rada STEVANOVIĆ3

REVIEW OF USE OF INDUSTRIAL PLASTIC WASTE IN ROAD

CONSTRUCTION
Abstract: This paper presents the review of the possibility of the plastic's use as a waste material in the
road construction industry. There are 46 different types of plastic that can be classified in two groups.
The classification into groups was carried out on the basis of the properties, ie. the possibility of their re-
use in the production process. Also, the types of plastics and products producted from these plastics
types are presented in this paper. The process of waste accumulation is explained as well. In addition,
some of the achieved results, regarding plastics use in various percentages in the asphalt mixtures, are
mentioned.

Кey words: industrial waste, plastic, properties of use.

PREGLED UPOTREBE INDUSTRIJSKOG PLASTIČNOG OTPADA U

PUTOGRADNJI
Rezime: U ovom radu napravljen je pregled mogućnosti upotrebe plastike kao otpadnog materijala, u
putnoj industriji. Postoji 46 različitih tipova plastike koji se mogu svrstati u dvije grupe. Prikazana je
podjela na grupe koja je izvršena na osnovu njihovih svojstava, tj. mogućnosti njihove ponovne
upotrebe u procesu proizvodnje. Nabrojane su vrste plastika i proizvodi koji su proizvedeni od tih vrsta
plastike. Objašnjeno je kako dolazi do stvaranja otpada. Navedeni su i neki od dosadašnjih rezultata
postignutih upotrebom plastike u različitim procentima u asfaltnoj mješavini.

Ključne reči: industrijski otpad, plastika, mogućnost primjene.

1
PhD Student, MSc CE, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering
and Geodesy, Trg Dositeja Obradovića 6 21000 Novi Sad, e-mail: milan-marinkovic11@hotmail.com
2
PhD, MSc CE, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, Trg Dositeja Obradovića 6 21000 Novi Sad, e-mail: bojanm@uns.ac.rs
3
Ass. MSc CE, University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and
Geodesy, Trg Dositeja Obradovića 6 21000 Novi Sad, e-mail: nikolic.rada @gmail.com

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1. INTRODUCTION
Asphalt concrete is a material which consists of mineral aggregate and bitumen.
Bitumen is used as a binding agent that envelops aggregate. Generally speaking,
when looking at the amount of material to be used, road construction is an expensive
proposition. Therefore, we strive to reduce our total cost of road construction using
cheaper materials such as industrial waste. In Serbia, annually, over 8.2 million tons
of industrial waste is produced [1], of which is 7.9 million tonnes of non-hazardous
waste. Only 19% of this waste is recycled which is far below the European average.
In 2012, it is generated 13 938 tonnes of hazardous plastic [2].

1.1. Types of plastics

There are two groups of plastic (Table 1) and 46 different types of plastic.

Table 1 – Groups of plastic

Thermoplastics Thermosetting
Polyethylene Teryphthalate Bakelite
Polypropylene Epoxy
Polivinil Acetat Melamine
Polyvinyl Chloride Polyester
Polystyrene Polyurethane
Low density polyethilene Urea-Formaldehyde
High density polyethilene Alkyd

The first group are thermoplastic materials and it includes materials such as PET,
PVC. The second group are thermosetting plastic or thermoset. This group includes
materials such as bakelite.

Figure 1 – Bakelite (black and white)

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The main difference between these two groups of plastics is in their properties
after passing through the manufacturing process. Thermoplastics are mainly
recyclable. Before production the thermosetting plastics are usually in liquid form or
in the form of a sticky resin. In such state, they are casted in the molds to give the
final product. During the curing process this mass is transformed through cross-
linking process. In this process, molecules with a higher molecular weight are formed.
In thermal processing thermosetting plastics change their structure, thus, produced
waste from this plastics is impossible to recast or reformat. This is the reason why we
tend to take care of plastic that belongs to this group, by using it as a supplement in
basic materials in road construction.
In order to facilitate the sorting of the plastic waste after use in the United States
of America, an association of Society of Plastics Industry introduced labels that
indicate plastic products (table 2). This labeling system was subsequently introduced
in Europe.

Table 2 - The types of plastics and their labels according to the SPI coding system
Plastics Designation Symbol
Polyethylene Teryphthalate
PET

High density polyethilene HDPE

Polyvinyl Chloride PVC

Low density polyethilene LDPE

PP
Polypropylene

Polystyrene PS

Other types of plastic Other

Table 3 shows the list of products that are made from certain types of plastic.

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[3]
Table 3 - Products that are made from certain types of plastics
Plastics Products
Polyethylene Teryphthalate Drinking water bottles, trays for frozen dinners
Polypropylene Bottle caps and closures, wrappers of detergent, biscuit,
vapors packets, microwave trays for readymade meal
Polyvinyl Chloride Mineral water bottles, credit cards, toys, pipes and
gutters; electrical fittings, furniture, folders and pens,
medical disposables; shampoo bottles, trays for food
Polystyrene Yoghurt pots, clear egg packs, bottle caps.
Foamed Polystyrene: food trays, egg boxes, disposable
cups, plastic cutlery, protective packaging for electronic
equipment and toys
Low density polyethilene Carry bags, sacks, milk pouches, bin lining, cosmetic
and detergent bottles.
High density polyethilene Carry bags, bottle caps, house hold articles
Bakelit Jewelry boxes, desk sets, clocks, radios, game pieces
like chessmen, poker chips, billiard balls, in
electrical insulators, radio and telephone casings,
kitchenware, pipe stems, firearms, and children's toys
Melamin Table, plates, parts in laminate floors, melamine
dinnerware

2. ADVANTAGES OF USE OF PLASTICS

According to Article 38 of the Law on Waste Management (Official Gazette RS
br. 88/10), the use of waste for the same product from which it was built, or for other
purposes, is permitted. The use of plastic waste in road construction primarily leads to
material resources use reduction, because instead of expensive materials, we use
waste that is practically free. Nevertheless, lower amounts of stone material reduces
the risk of injuries of workers in quarries. It also results in savings of space required
for storage of waste materials and reduces environmental pollution.

3. RESULTS ACHIEVED BY USING PLASTIC

When waste is used as material for road constructio, it is usually as filler which
has a role to replace some portion of the stone material or they are used together with
bitumen to replace a certain percentage of bitumen. The same goes for plastic waste.
If the plastic has a lower softening temperature than 170 °C, it is used as an addition
to bitumen. If the plastic has a higher softening temperature than about 170 °C, it can
be used as a supplement to filler.
The following table presents the properties of individual types of plastics (table 4).

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Table 4 - The behavior of a plastic polymer under the influence of temperature [3]
Polymer Decomposition Products Flash point Products
temperature (in ºC)
(in ºC)
PE 270-350 CH4 , C2H6 > 700 CO,CO2
PP 270-300 C2H6 > 700 CO,CO2
PS 300-350 C2H6 > 700 CO,CO2
PVC 320-350 C2H6 , HCl > 700 CO,CO2 , Cl2, HCl

Figure 2 – Bakelite after heating on 220 ºC

In previous studies the samples were formulated with the several different
quantities of plastic. The percentage of plastic is used in the ratio to the quantity of
bitumen. Plastics were used between 0% and 15% relative to the quantity of bitumen.
Previous studies have examined the use of the following types of plastics: PET,
ABS[5], HIPS[5], HDPE, LDPE, bakelite. In some tests, chemical additives were
used to make better contact between binders and aggregates. The application of
plastics provides an improvement in terms of rutting reducing and performance at
high temperatures.

4. CONCLUSION
As the human population gets larger, quantities of waste are also getting larger. A
particular problem is the waste that can not be recycled and therefore we should strive
to increase the number of tests for the possible use of waste in asphalt mixtures. The
main criteria to be fulfilled are: economically visible use of waste and improvement
regarding the performance of materials in relation to a conventional materials.

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ACKNOWLEDGEMENTS
The work reported in this paper is a part of the investigation within the research
project TR 36017 "Utilization of by-products and recycled waste materials in concrete
composites in the scope of sustainable construction development in Serbia:
investigation and environmental assessment of possible applications", supported by
the Ministry for Science and Technology, Republic of Serbia. This support is
gratefully acknowledged.

REFERENCES
[1] The Agency for Environmental Protection (2014): Announcement
[2] The Republic Institute for Statistics (2012): Industrial waste in Republic of
Serbia, 2012., Announcement, pg.2
[3] R.Vasudevan, S.Rajasekaran, S.Saravenavel (2005): Utilisation of Waste Plastics
in Construction of Flexible Pavement; GPEC 2005-PED Division
[4] Amit Gawande, G. S. Zamre, V. C. Renge, G. R. Bharsakale, Saurabh Tayde
(2012): Utilization of Waste Plastic In Asphalting of Roads; Scientific Reviews &
Chemical Communication, 2277-2669,str.147-156
[5] B.W. Colbert, Z. You, P. Heiden (2012): The Mechanical Performance of
Asphalt Binders Modified With Free Radical Treated Electronic Waste Plastics

[594]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.131.1
1
Mladen MILANOVIC
Milan GOCIC2
Mihailo MITKOVIC3
Slavisa KONDIC4
Slavisa TRAJKOVIC5

INDICATORS OF SUSTAINABLE GREEN BUILDING

Abstract: The world faced with the great challenges such as climatic changes, environment
endangering and socio-economic inequalities during the past decades. The complexity of previous
problems has caused the need for the introduction of new concept of development i.e. sustainable
development. The concept of sustainable development has the major role in modern civil engineering
and architecture, and it leads to sustainable green building.
This paper analyzes the indicators of sustainable development and their application for the green building
objects. The case study includes the analysis of green roof construction at the Faculty of Civil
Engineering and Architecture..

Кey words: Sustainable development, green building, green roof.

INDIKATORI ODRŽIVE ZELENE GRADNJE

Rezime: Poslednjih decenija svet se suočava sa velikim izazovima kao što su klimatske promene,
ugrožavanje životne sredine i socio-ekonomske nejednakosti. Složenost prethodno navedenih problema
je uslovila potrebu za uvođenjem novog koncepta razvoja tj. održivog razvoja. Koncept održivog razvoja
ima važnu ulogu u modernom građevinarstvu i arhitekturi, i doveo je do održive zelene gradnje.
Rad analizira indikatore održivog razvoja i njihovu primenu na objekte zelene gradnje. Studija slučaja
obuhvata analizu konstrukcije zelenog krova na Građevinsko-arhitektonskom fakultetu.

Ključne reči: Održivi razvoj, zelena gradnja, zeleni krov.

1
MSc, Faculty of Civil Engineering and Architecture, A. Medvedeva 14, Nis, Serbia, mmsmladen@gmail.com
2
Dr, Faculty of Civil Engineering and Architecture, A. Medvedeva 14, Nis, Serbia, mgocic@yahoo.com
3
MSc, Faculty of Civil Engineering and Architecture, A. Medvedeva 14, Nis, Serbia
4
MSc, Faculty of Civil Engineering and Architecture, A. Medvedeva 14, Nis, Serbia, skondic555@gmail.com
5
Dr, Faculty of Civil Engineering and Architecture, A. Medvedeva 14, Nis, Serbia, slavisa@gaf.ni.ac.rs

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1. INTRODUCTION
The world faced with the great challenges such as the climate changes,
environment endangering, large gap between the developed and developing states,
and social problems during the past decades. During the seventies years of 20th
century, these challenges caused the appearing of new concept of development named
sustainable development that is based on three aspects i.e. economic, social and
environmental aspects.
The building industry consumes large amount of natural resources [1]. This fact
causes the needs for development of sustainable building i.e. green building. Primary
concept of green building is based on ecological principles without of detrimental
impacts on environment.
Researchers have analyzed the concept of green building and especially green
roofs, which provide aesthetic and environmental advantages of buildings [1-5].
This paper presents the analysis of sustainable development system, its
connections and influence on green building and especially on green roofs. Two
groups of sustainable development indicators vital for green building are presented.
The case study includes green roof construction at the Faculty of Civil Engineering
and Architecture.

2. SUSTAINABLE DEVELOPMENT
The economic growth was the primary goal in the social development during the
past. Further exploitation of resources started to be dangerous for the environment.
The concept of sustainable development is imposed as a solution between protection
of environment and development goals of society.
Sustainable development represents a system in which the economic development
without threatening the environment and social development will be realized [6]. This
kind of development has an influence on all sectors of society and nature, and for that
reason there is no unique definition of sustainable development. There is a balance
between the use and recovery of resources in this system as well as awareness that the
future generations will be dependent on our earlier behavior. Sustainable development
gives guidance how to achieve previously defined plans in the best way.
The concept of sustainable development is defined to connect the three important
aspects [7, 8]: 1) economic, 2) environmental and 3) social.
Economic aspects of sustainable development are based on compatibility of
economical development with resources. They can be observed through the
production, economic interest and consumption.
Environmental aspects should enable maintenance of biodiversity, a stable
resource base and its rational use. Also, these aspects include the reduction of
environmental protection, care of endangered species and ecosystems.

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Social aspects refer to social relations, respect of human rights, adequate provision
of social services and the involvement of people in decision-making processes.

3. GREEN BUILDING INDICATORS

3.1. Green building
The concept of sustainable development leads to the new concept in civil
engineering named green building. It represents a way to achieve the sustainability in
civil engineering [3]. This process follows the green object through all sectors of
building life, which includes planning, designing, constructing, operating,
maintaining and removing buildings using the concepts of sustainability.
Using the green building, it is possible to achieve the growth of economics and the
quality of life and to reduce the adverse influence on the environment.
The main aims of green building are [1]: to increase efficiency of using the energy,
water and materials and to reduce the influences on human health and environment.
These aims can be achieved by using the sustainable materials, building the energy
efficient objects using the new methods of building and providing the ecology
sustainable energy resources.
Green building benefits can be classified as environmental, economic and social
benefits [2, 3], Table 1.
Table 1 - Green building benefits
Green building benefits
Environmental Economic Social
- enhance and protect - reduce operating and - enhance occupant
biodiversity and ecosystems maintenance costs comfort and health
-improve air and water - create, expand and shape - heighten aesthetic
quality markets for green product qualities
- reduce waste streams and services - minimize strain on local
- conserve and restore - improve occupant infrastructure
natural resources productivity - improve overall quality
- minimize global warming - optimize life-cycle of life
economic performance
- improve the image of
building
- reduce the civil
infrastructure costs

In order to conduct the certification of buildings built as green buildings, a huge

number of green standards have been developed such as Leed, Breeam, DGNB,
Casbee, and Green Star.
If a building achieves the green building standards, its market price will be higher.
That increases economic efficiency, protection and restoring of ecological systems
and improving human well-being.

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3.2. Green building indicators

The UN provided the guidelines and methodology for the selection of indicators
[9] where the importance of using the indicators on a national level is emphasized. A
large number of countries developed their national set of indicators representing the
UN recommendations adapted to the national needs.
By implementing a concrete selected set of sustainable building, it is possible to
analyze certain areas such as the green building development.
The most important element of the sustainable development is the increase of
energy efficiency at all sectors of economy [10]. Low energy efficiency is a limiting
factor of industrial development. The following indicators are designed for
monitoring the energy efficiency of green buildings:
 the number of employees in the companies that have introduced cleaner
production principles,
 the reduction of losses in natural transport and distribution,
 full cost recovery prices for established energy.
Apart from energy efficiency of green building, the indicators show the
successfulness of the care about the environment stand apart as well:
 the number of ecological incidents and damage,
 percentage of budget spending on environmental protection,
 percentage of total recycled waste, and
 carbon dioxide emissions.

4. GREEN ROOFS
The contemporary concept of green roofs was created only with the development
of the reinforce concrete in the second half of 19th century with the emergence of
contemporary styles in architecture. In the future, there may even be not only green
roofs, but green architecture, which will be an integral part of a structure in the
esthetic and functional terms [4].
Green roofs are roof structures specially engineered and covered by necessary
layers for planting the vegetation. There are several different classifications of green
roofs according to different criteria. The most widely spread classification is related
to the growing vegetations: intensive and extensive green roofs [5]. Intensive roofs
are thicker and can support several kinds of plants, but they are heavier and require
more maintenance. Extensive roofs are covered by the thin layer of vegetation and
they are lighter than the intensive green roofs.
The advantages of green roof in comparison with the classic roofs are:
 soil is an excellent thermal insulation and alleviates the effects of external
temperatures,
 the need for heating (in winter) and for cooling (in summer) is reduced and
energy is saved,

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 soil is an excellent soundproofing material, and it reduces external noise,

 during heavy rainfall, the soil retains water for a time, and it is partially
consumed by the plants, while the rest drains slowly so there is no violent runoff
of precipitation water (drainage of excessive water is a problem which is difficult
to solve in civil engineering), and
 the characteristic layers are protected by soil from the effects of rain, wind and
UV radiation, so their service life is longer than the classic roofs (4-8 times).

5. CASE STUDY
The Faculty of Civil Engineering and Architecture produced a conceptual design
of the Innovation center [11]. By extending the faculty building, new designed
building is located above the part of the building in the ground level, containing the
entrance hall and amphitheaters.
Cross section of the Innovation center is shown in figure 1.

Figure 1 – Cross section of the innovation center

The roof of the innovation center is designed as a green roof. Figure 2 shows the
south side of the Innovation center with cross section of green roof layers.

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Figure 2 – South side of the innovation center

Roof plateau surrounding new designed structures thar are cosntructred as a flat,
impassable terrace – green roof. Adequate hydro-insulation is designed, with the
following layers (top to bottom) layer of soil with the plants 10 cm, drainage layer
Sarnavert Aquadrain 550 or smilar. FPO membrane Sarnafil TG 66 or similar, layer
of concrete, average depth 7 cm, PE foil, rigid insulation plates of rock mineral woll
20 cm thick, vapor dam Sarnavap 1000 E, existing floor slab.

Figure 3 – Conceptual design of Innovation center

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The formal concept of new designed building is a continuation of the orthogonal

form of the existing structure. The simple architectonic form dominated by the large
glazed surfaces and the overhang along the entire building, has a goal of harmonious
fitting of new designed structure into the prominently horizontal volume of the
existing structure, figure 3.

6. CONCLUSION
The paper analyses the sustainable development by using its three aspects
(economic, environmental and social), which are used in civil engineering. Using the
trend of sustainability in all sectors of society, and especially in green building, the
concept of green roofs becomes the unique solution. Also, the analyses included two
most important groups of indicators for green building, i.e. indicators for energy
efficiency and for environment. The case study presents constructed green roof at the
Faculty of Civil Engineering and Architecture in Nis.
Number of countries insists that new buildings should be built according to green
building principles. Green building is still in growth in Serbia. The future will be
oriented to analysis of the influence of other indicators of sustainable development on
development of green building.

REFERENCES
[1] Bribian, I.Z., Capilla, A.V., Uson, A.A. (2011): Life cycle assessment of
building materials:Comparative analysis of energy and environmental impacts
and evaulation of eco-efficiency improvement potential, Buiding and
Environment, 46, 1133-1140.
[2] Nilashi, M. et al. (2015): A knowledge-based expert system for assessing the
performance level of green buildings, Knowledge-Based Systems, 86, 194-209.
[3] Ahn, Y.H. (2010): The Development of Models to Identify Relationships
Between First Costs of Green Building Strategies and Technologies and Life
Cycle Costs for Public Green Facilities, Doctor dissertation, Virgina Polytechnic
Institute and State University, Blackburg, Virginia.
[4] Nikolić, V. (2009): Estetski i ekološki aspekti primene zelenih krovova,
Nauka+praksa, 12, 147-150.
[5] Lennep, E., Finn, S. (2008): Green Roofs Over Dublin, A green roof policy
guidance paper for Dublin, Tepui, Dublin.
[6] Emas, R. (2015): the Concept of Sustainable Development: Definition and
Defining Principles, Brief for GSDR 2015, 1-3.
[7] Haris, J. (2003): Sustainability and Sustainable Development, International
Society for Ecological Economics, Encyclopedia of Ecological Economics, 1-12.

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iNDiS 2015 - PLANNING, DESIGN, CONSTRUCTION AND BUILDING RENEWAL

[8] Giddings, B., Hopwood, B., O’Brien, G. (2002): Environment, Economy and
Society: Fitting the Together into Sustainable Development, Sustainable
Development, 10, 187−196.
[9] United Nations (2001): Indicators of Sustainable Development: Guidelines and
Methodologies, Second Edition, UN Sales Publication No.E.01.II.A.6, New
York.
[10] Action plan for the implementation of the national sustainable development
strategy for the period 2011-2017, Official Gazette of the Republic of Serbia, No
31/10, 2010.
[11] Građevinsko-arhitektonski fakultet (2015): Idejni projekat inovacionog centra,
Niš.

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PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Marina PEŠIĆ
Nenad PEŠIĆ2
Nikola GAROVNIKOV3

ENERGY EFFICIENCY AUDITING OF PUBLIC OBJECTS IN FIVE

MUNICIPALITIES IN MONTENEGRO
Abstract: Municipalities of Bar, Ulcinj, Budva, Kotor, Tivat and Old Royal Capital Cetinje were the
beneficiaries of the EU-funded (IPA) project “Improvement of Energy Efficiency through an Inter-
Municipal Management Network. This project aimed to improve energy efficiency in public sector in
southern Montenegrin region and to find best solutions for future investments. Summary report on
preliminary energy audits of public buildings, public lighting, waste water systems and water supply
systems were completed. Representative public objects from each municipality are taken and
simultaneously analysed. Audits are developed for each object for the current state and after the proposed
measures are implemented. The results are compared and the comments are given.

Кey words: energy efficiency, energy audits, renewable energy sources.

ANALIZA ENERGETSKE EFIKASNOSTI JAVNIH OBJEKATA U

PET OPŠTINA U CRNOJ GORI
Rezime: Zajednica opština Bar, Ulcinj, Budva, Kotor, Tivat i Stara Kraljevska Prestonica Cetinje
korisnik je fonda EU (IPA) za projekat „Unapređenje energetske efikasnosti kroz međuopštinsku
upravljačku mrežu“. Cilj projekta je unapređenje energetske efikasnosti u javnom sektoru u južnoj regiji
Crne Gore i iznalaženje najboljih rešenja za buduća ulaganja. Potrebno je dati Sumarni izveštaj
energetskih pregleda javnih objekata, javne rasvete, sistema vodo-snabdevanja i sistema otpadnih voda.
Za potrebe ovog rada, karakteristični javni obekti iz svake opštine su obrađeni i paralelno analizirani.
Auditi su sastavljeni za postojeće stanje i za stanje nakon sprovođenja predloženih mera unapređenja en.
ef. Rezultati su upoređeni i komentarisani.

Ključne reči: energetska efikasnost, energetski pregledi, obnovljivi izvori energije.

1
Master of Science, Koning Ltd. Novi Sad, Danila Kiša 7, 21 000 Novi Sad, Serbia, marinapkoning@gmail.com
2
Master of Science, Koning Ltd. Novi Sad, Danila Kiša 7, 21 000 Novi Sad, Serbia, contact@koning.rs
3
Master of Science, Bluewaters Environmental Consultants, Amalienstrasse 3, 1130 Vienna,
nikolagarovnikov@gmail.com

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1. PROJECT DESCRIPTION
The main objective of this assignment is to perform preliminary energy audits of
the public buildings and other facilities under jurisdiction of Local Self Government
of Ulcinj, Budva, Tivat, Kotor and Old Royal Capital Cetinje. According to EBPD
requirements and national legislation these audits can be performed only by trained
professionals for energy auditing. Audits performed will provide sufficient
information for energy efficiency improvements and all necessary data for already
established Central Information System of Energy Consumption (CISEC) as well as
National Information System for Monitoring and Verification of Energy Savings.
Audits will also represent a basis for consideration of present building stock
conditions giving overview of constructive and energy performances. All these
information are necessary for future analyses, programs and plans, as well as
benchmark comparisons.
In order to fulfil this task on best way possible, the team of experts analysed
technical documentation of all buildings and other facilities, firstly, then collected all
information on energy (electricity, energy and sanitary water) consumption, and
visited sites in order to compare facts from technical documentation and on site and to
collect missing data. These site visits served to collect all information which do not
exist in technical and design documentation and to make interviews with staff
responsible for energy consumption, maintenance, interventions etc.

2. CHARACTERISTIC PUBLIC BUILDINGS

2.1. City Hall in Ulcinj

Figure 1 – Characteristic picture of the object

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The object was built in 1968 in prefabricated RC system. Walls are 10cm in
thickness, with no thermal insulation. The doors and windows are old, timber in a
poor condition. Some of the windows are replaced with new PVC ones. However,
these windows do not have adequate thermal properties.
The object is located near the centre of Ulcinj. It is detached from the surrounding
buildings and partially protected from noise and overheating with greenery which is
surrounding the building. Facades are in poor condition, due to lack of maintenance.
Small cracks and imperfections can be noticed, but no major structural damages.
The boiler room exists, but is not in use. All heating/cooling is performed via split
systems. Water consumption is not significant. Most of the electricity is used in
summer for cooling and in winter for heating.
2.2. City Hall in Old Royal Capital Cetinje

Figure 2 – Characteristic picture of the object

The object was built of stone in 1932. Walls are 65 cm in thickness, with no
thermal insulation. Windows and doors are old, with double frames, made of timber,
in poor condition. The object is under protection of the state, and nominated for the
UNESCO world heritage sites.
Object is located near the center of Old Royal Capital Cetinje. It is detached from
the surrounding buildings and partially protected from noise and overheating with
greenery which is surrounding the building. Facades are in fine condition. The roof
was recently repaired, adding thermal insulation.

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Biler room exists, and that is the main way of heating. Cooling does not exist.
Three split systems are installed on the whole object. Since the object is protected ac
a cultural monument, air-coditioning units shall be removed from the facades.
2.3. City Hall in Tivat

Figure 3 – Characteristic picture of the object

Object is located at Trg Magnolija, the main administrative square. It is detached

from the surrounding buildings and partially protected from noise and overheating
with greenery which is surrounding the building. Object was built in 2013; therefore
facades and carpentry are in fine condition.
The object was built of RC and blocks, with 5cm insulations. Since Tivat is in 1st
Climate zone of Montenegro, as stated in Energy Performance Requirements, this
thermal envelope shall be satisfying. Thermal pump is used for both, coolig and
heating. Surprisingly, electricity consumption was quite high.
2.4. City Hall in Budva
Object is located near the centre of Budva. It is detached from the surrounding
buildings and partially protected from noise and overheating with greenery which is
surrounding the building. Facades are in fine condition, but with no thermal
insulation. Small cracks and imperfections can be noticed, but no major structural
damages.
Most of the doors and windows are replaced. Thermal properties were not taken
into account when ordering. Boiler room exists, but it is not in use. Electricity is
mainly used for cooling and heating, via split systems. New chillers were installed in
the assembly hall. Water consumption is not sigifficant.

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Figure 4 – Characteristic picture of the object

2.5. Zgrada Obnove in Kotor
Object is located in Škaljari, 1km from the center of Kotor. It is detached from the
surrounding buildings and protected from traffic noise, even though there is lack of
greenery. Even though it was built in 1981, it is not energy efficient, and at the same
time it is in quite poor condition.
Prefabricated RC panels were used for ceiling, while the walls were built with
only 8cm insulation between two thin metal sheets.

Figure 5 – Characteristic picture of the object

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3. RESULTS´ COMPARISON
Table 1 gives overview of the average electricity consumption for each object in
each month. Table 2 gives overview of the electricity consumption for each object per
square meter. Specific consumption for all objects is given in following figures as
well. This method of expressing electricity consumption per square meter was used in
order to make results comparable.

Таble 1- Total electricity consumption before and after energy efficiency measures´
implementation
Total electricity consumption before and after energy efficiency measures´ implementation
Ulcinj City Hall Cetinje City Hall Budva City Hall Tivat City Hall Kotor - Zrada Obnove
Object
NKP [m2] 2399.00 NKP [m2] 8820.00 NKP [m2] 2367.00 NKP [m2] 3863.93 NKP [m2] 1640.00
Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE
Month
[kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh]
January 134993.23 23904.92 395891.09 123151.88 132344.69 11727.17 88073.14 74267.35 51702.50 20917.43
February 102157.26 16331.54 308860.45 99488.95 98513.06 8355.96 92508.40 65907.14 38064.27 15149.16
March 53995.01 24044.36 239855.45 79586.37 56139.71 8718.38 91367.05 63185.53 21112.31 8439.83
April 70269.51 33664.88 105477.70 38548.87 23843.43 12875.91 73286.78 48419.80 21955.01 13485.89
May 150175.30 49735.60 134727.57 53265.87 101142.83 21291.42 83811.55 52066.13 47690.68 23156.56
June 214588.27 57460.42 203650.37 70783.54 160615.29 24206.59 91048.71 59791.61 70155.72 32545.60
July 252588.17 64970.23 389454.95 130604.21 195379.87 27932.09 128340.01 86931.44 82130.63 35393.98
August 240803.18 62701.25 376762.48 126936.11 189341.52 27685.55 138543.73 93910.02 76341.32 35049.31
September 149276.24 46650.18 109709.55 43477.71 106884.76 20248.36 109709.12 70572.54 42038.55 20447.58
October 73478.05 33698.81 105419.98 35732.76 36660.13 14337.53 98783.72 64755.12 17960.92 10609.50
November 56042.65 14948.39 238515.35 77035.47 52599.78 8786.25 88423.57 64437.58 25225.66 9807.36
December 134550.92 23416.65 373481.76 121193.40 125188.99 11466.35 121276.48 86086.16 49055.25 19861.42
Total: 1632917.77 451527.21 2981806.70 999805.15 1278654.07 197631.54 1205172.27 830330.42 543432.82 244863.62

Таble 2- Specific electricity consumption before and after energy efficiency measures´
implementation
Speciffic electricity consumption before and after energy efficiency measures´ implementation
Ulcinj City Hall Cetinje City Hall Budva City Hall Tivat City Hall Kotor - Zrada Obnove
Objekat
NKP [m2] 2399.00 NKP [m2] 8820.00 NKP [m2] 2367.00 NKP [m2] 3863.93 NKP [m2] 1640.00
Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE Before SMUEE After SMUEE
Month
[kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh] [kWh]
January 56.27 9.96 44.89 13.96 55.91 4.95 22.79 19.22 31.53 12.75
February 42.58 6.81 35.02 11.28 41.62 3.53 23.94 17.06 23.21 9.24
March 22.51 10.02 27.19 9.02 23.72 3.68 23.65 16.35 12.87 5.15
April 29.29 14.03 15.28 4.37 10.07 5.44 18.97 12.53 13.39 8.22
May 62.60 20.73 23.09 6.04 42.73 9.00 21.69 13.47 29.08 14.12
June 89.45 23.95 44.16 8.03 67.86 10.23 23.56 15.47 42.78 19.84
July 105.29 27.08 42.72 14.81 82.54 11.80 33.21 22.50 50.08 21.58
August 100.38 26.14 12.44 14.39 79.99 11.70 35.86 24.30 46.55 21.37
September 62.22 19.45 12.44 4.93 45.16 8.55 28.39 18.26 25.63 12.47
October 30.63 14.05 11.95 4.05 15.49 6.06 25.57 16.76 10.95 6.47
November 23.36 6.23 27.04 8.73 22.22 3.71 22.88 16.68 15.38 5.98
December 56.09 14.87 42.34 13.74 52.89 4.84 31.39 22.28 29.91 12.11
Total: 56.72 16.11 28.21 9.45 45.02 6.96 25.99 17.91 27.61 12.44

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100.00 40.00
Budva City 30.00 Tivat City
50.00 Hall NKP 20.00 Hall NKP
[m2] Before 10.00 [m2]
0.00 SMUEE 0.00 Before
July

July
October

October
April

April
January

January
[kWh] SMUEE
[kWh]

60.00 Kotor -
40.00 Zrada
20.00 Obnove
NKP [m2]
0.00
Before
July
October
April
January

SMUEE
[kWh]

It can be conclude that City Halls in Ulcinj and Budva, have largest electricity
consumption, especially in summer period. This proves that electricity is mostly used
for cooling. Electricity consumptio for heating, during winter, is significant as well,
and again, same two objects show highest consumption, therefore lowest energy
properties. Both of these object were made of precast RC elements, with no thermal
insulations neither in walls, nor in the roof.
City Hall in Tivat showed best properties, which was expected, since the object
was build in 2013 and the desiger was following current requirements form the Law
on energy efficiency.

4. CONCLUSION AND RECOMMENDATIONS

Measures for improving energy efficiency in buildings are divided in three groups:
a) “No” or low cost energy efficiency measures

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 Increase consciousness: choose energy dissipation characteristic cases, make

calculations and show employees how much energy and money is wasted,
and teach them how to save energy, improving their everyday habits,
 Improve regular maintenance: a large amount of energy is wasted due to
poorly maintained windows, doors, pipes with hot water, air-conditionig
systems, boilers, etc.
b) Medium investment energy efficiency measures
 Improving thermal envelope on the object - transparent and non-transparent
surfaces,
 Shading glazed surfaces exposed to direct sunlight,
 Application of bioclimatic principles.
c) High investment energy efficiency measures
 Boliers using oil as energy source shall be changed for those using pellet.
Pellet is renewable energy source which can be provided nearby. Heating cost
can be significantly reduced.
When considering investment return period, it is cleat that first group of measures
shall be implemented instantly, since they consider mostly education of the
employees and regular maintainance of the building.
After implementing first two groups of energy efficiency improvement measures,
the savings will be very large. Of course, we shall be reminded that City Hall in
Cetinje is under protection as cultural heritage, therefore certain measures are
forbiden, such as placing new thermal envelope on the exterior side of the façade
walls.
High investment energy efficiency measures shall be considered as well. New
boilers using renewable energy sources would be smart and environmentally friendly
solution for improving energy efficiency of the object.

[610]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Igor SVETEL
Marko ЈАRIĆ2
Nikola BUDIMIR3

TOWARD MODEL INFORMED ENERGY EFFICIENCY DESIGN

Abstract: Lately, a merger of the BIM and energy simulation software was seen as the solution for the
energy efficiency design. The idea was based on the assumption that BIM software can produce general
building model that can provide all necessary information for the energy simulation software.
Unfortunately, the current level of technology development does not support streamlined energy
efficiency design process. The paper discusses main obstacles in the current technology that postpone
their application in everyday design process, and concludes with the proposal for further research and
software development toward computer assisted design process where information model plays central
role and enables designer to better understand energy requirements of the building.

Кey words: BIM, energy simulation, energy efficiency design, information model

PREMA ENERGETSKI EFIKASNOM PROJEKTOVANJU

ZASNOVANOM NA MODELU
Rezime: U poslednje vreme BIM i softver za energetsku simulaciju su viđeni kao rešenje za energetski
efikasno projektovanje. Ideja je bazirana na pretpostavci da BIM softver proizvodi opšti model građevine
koji pruža sve neophodne informacije programima za energetsku simulaciju. Na žalost, trenutni razvoj
tehnologija ne omogućava kontinualni proces energetski efikasnog projektovanja. Rad razmatra glavne
prepreke u postojećoj tehnologiji koje usporavaju njihovu primenu u svakodnevnom projektovanju i daje
predlog za dalje istraživanje i razvoj softvera prema računarski podržanom projektovanju gde
informacioni model igra centralnu ulogu i omogućava projektantu da bolje razume energetske zahteve
građevine.

Ključne reči: BIM, energetska simulacija, energetski efikasno projektovanje, informacioni model

1
dr, Innovation Center, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, isvetel@mas.bg.ac.rs
2
dr, Innovation Center, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, mjaric@mas.bg.ac.rs)
3
dr, Innovation Center, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, nbudimir@mas.bg.ac.rs

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1. INTRODUCTION
Most today programs for building energy consumption simulation appeared in the
late 1970s, and were refined during 1980s. With the expansion of PC computers in
1990s these applications became available to wider audience. At that time, their
widespread adoption in everyday practice was suppressed because applications
required 3D computer models of the building. However, architectural practice was
based on paper documentation, and 2D drafting programs where considered as the
state of the art technologies. Lately, with the advent of the Building Information
Modeling (BIM) technology that enables creation of the building models composed
from components that mimic real physical building elements, containing not only 3D
geometrical information, but also information about materials, their properties, and
rules describing constraints and relations among objects, the merger of BIM with
existing energy consumption simulation programs was seen as the solution for the
energy efficiency design.
The paper discusses three main obstacles in the current technology that prevent
seamless integration of technologies: 1) current BIM applications do not construct
general building model, instead each application uses different modeling concepts
making their models incompatible, 2) interoperability formats like IFC and gbXML
provides just data structures for information interchange between applications, but do
not prescribe which information is necessary for each particular energy simulation
application, and 3) the information flows in one direction from BIM applications
toward energy simulation applications. The paper concludes with the proposal for
further research and software development toward computer assisted design process
where information model plays central role and enables designer to better understand
energy requirements of the building she/he designs, and to develop more efficient
solutions.

2. BUILDING MODEL
At first glance, the BIM applications like ArchiCAD and Revit exhibit similar
functionality. The user chooses among different building components (like wall,
ceiling, roof, window, door, plumbing, etc.), then in appropriate dialog box specifies
values of the parameters to define specific building component that is part of her/his
design. When all necessary parameters are defined, the designer chooses location of
the component in the building model. Finally, the application launches its core
mechanism and updates the model according to defined parameters and inherent
composition rules.
It comes as no surprise that each BIM application applies specific core
mechanism. But in BIM this difference is fundamental and impacts on the way the
technology is applied in the actual design practice. In the paper we are discussing
differences among two BIM applications that are most prevalent in the Serbian
market – ArchiCAD and Revit.

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Starting with building components, the designer will quickly recognize that both
applications does not share the same basic set of components. Also same components
in different applications exhibit diverse composition behavior. Soon, the designer will
discover that she/he can download from the internet missing or enhanced
components, that each application requires different file format, and that if the
component is not available for your application there is no general substitution.
This brings us to the core mechanisms that ArchiCAD and Revit use to construct
their models.
The ArchiCAD uses Geometry Description Language (GDL) to describe all
application components. It is a BASIC like programming language that defines
parameters, object geometry, user interface display, behavior, and other necessary
information. The language is flexible and enables definition of any geometry,
inclusion of custom parameters, and even creation of custom user interface. The
designer‟s experience when using ArchiCAD resembles virtual construction or mock-
up making. The designer first shapes building component that she/he is going to
include in model by defining appropriate parameters. While doing, she/he can
constantly monitor parameter‟s effect on component by watching 3D preview. After
the component is located, the system applies rules and includes component in the
model. If the component does not fit appropriately in the model, the designer can
make further modifications to achieve perfect fit. Some real building logic is included
in the system, for example windows and doors become part of the wall in which they
are located and when wall is moved, windows and doors move together with the wall.
Also, when two walls are connected the system takes care about appropriate
trimmings and connects together same materials in two walls. But, if one wall is
moved, established connection breaks apart, and designer has to make all necessary
modifications. In large models manual update of revisions becomes tedious and time
consuming task.
The Revit is an application designed from the beginning to achieve effective
revision update. Its name is invented to imply for “revise instantly”. To achieve that
goal, designers devised core mechanism that is based on relations among elements
that enables quick propagation of modifications from one component to all related
components. Since the relationships between elements represent piece of the core
mechanism, the components that are part of the application library are predefined as
the families. If the designer wants to create custom building component she/he
chooses family that suits her/his needs and adapts it to achieve desired results. This
kind of “machine like” behavior is apparent during modeling process. When the
designer defines parameters he can not see how they influence component that she/he
is shaping. After the designer chooses location for the new component the system
checks relations between all components and reports to the user about all found
inconsistencies that have to be resolved before component is included in the model.
The system does not allow small user‟s adaptations after the element has become part
of the model. Contrary to the ArchiCAD, all relations once established (like
connection between two walls) will apply during all further model revisions. If, for

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example, designer moves one wall, all walls already connected to it will automatically
change their dimensions to preserve connections.
The ArchiCAD and Revit use two significantly different core mechanisms to
accomplish similar task. Differences are such that some instructors even prevent their
disciples to think of components in one application in terms of other application. It is
obvious that different core mechanisms and resulting diverse models prevent
development of unified BIM design method, and as the consequence it is impossible
to treat BIM as the general solution for the computer assisted green building design.
The building models created with ArchiCAD and Revit are rich models containing
both detailed information about geometry and information about building materials,
spaces and zones in the building, their occupancy type and daily schedules.
Unfortunately, these models are too detailed for the current building energy
consumption simulation applications. At the time when most energy simulation
algorithms were developed 3D building models were scarcity, and computers did not
had enough power to accomplish complex calculations. For that reason computer
applications were based on simplified models. In the meantime, algorithms were
refined and achieved level of good prediction so at the moment nobody sees no need
to change the model on which energy consumption simulation applications are based.
Instead, these simplified models coupled with the related results acquired status of
Building Energy Models (BEM). The process of transforming BIM model to a BEM
model is not straightforward and requires many specific operations depending on the
BIM application and target energy consumption simulation application [6].

3. INTEROPERABILITY FORMATS
The field of computer assisted building design was confronted with diverse
applications having proprietary data formats from its beginning and diverse
interoperability formats, primarily geometry oriented, were devised. In 1994
Autodesk started initiative on defining set of classes that could support development
of AEC (architecture, engineering, and construction) software. This initiative led to
formation of industry consortium that devised Industry Foundation Classes (IFC)
standard [2]. It is a neutral and open object oriented data model developed to attain
highest level of interoperability in AEC. The standard defines classes necessary to
represent all concepts related to building during its lifecycle and is registered as the
ISO 16739:2013 standard [4]. The standard is anticipated to provide data interchange
without information loss among all AEC applications and unified model-based
description of all building components.
Initially, it was thought that IFC can function as the neutral and open building
model. But soon, it was recognized that incompatibilities between BIM applications,
caused by their core mechanisms, make such an idea impossible. Additionally,
richness and flexibility of IFC standard intended to enable data transfer among all
AEC applications and to provide space for future new products and techniques has led
to confusion in the data exchange. This led to the development of strict definitions

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what information is necessary in particular data exchange and clear specification of

what data structures are used. The result that is now introduced in majority BIM
applications is the IFC 2x3 Coordination View 2.0 [3].
Despite all efforts, data exchange using IFC format is not a seamless process.
When one application exports data as IFC it translates its internal building model to
IFC format according to IFC 2x3 Coordination View 2.0. Since the specification is
not intended to transfer all information, data specific to one particular BIM
application will not become part of IFC file. On import side the problem is increased
since every BIM application interprets building blocks in IFC file and tries to
reconstruct how to create this component using native mechanism. The IFC file
contains only information on current state of particular component and importing
application needs to reconstruct how this particular state can be achieved using
application‟s core mechanism. In this process many specific information not shared
between all applications will be lost, like for example information about relations that
is specific only to Revit application. When we come to the problem of exporting BIM
model for the use in energy simulation software the situation is even worse. The IFC
2x3 Coordination View 2.0 covers only coordination between the architectural,
mechanical and structural engineering tasks during the design phase. No official
model view definitions exist for the use of IFC format in the energy simulation. So
the process is based on try-and-error method and that is the reason why only one
commercial energy simulation application uses IFC format to import building model
for further analysis.
The Green Building XML schema – gbXML [1] is the format based on the
Extensible markup language (XML) developed to facilitate data exchange between
digital building models and the energy simulation applications. Its geometric
requirements deal only with spatial volumes and thermal zones with simple boundary
surfaces. BIM application that supports must export its complex model information in
a simplified form. This process is not regulated in any particular way, so every
application performs that task in a way that developers believed to be best. And only
when the designer tries to import such file to particular energy simulation application
that she/he finds errors. And sometimes energy simulation application simply
proclaims the file to be invalid and leaves the designer without any answer how to
establish connection between two applications [6]. Different simulation programs
may have different software architectures, different algorithms to model building and
energy systems, and require different user inputs even to describe the same building
envelope or HVAC system component. The existence of the gbXML provides only
standard data structure for information transfer and the task of preparation appropriate
data depends on the detailed knowledge of each particular energy simulation
application.

4. INFORMATION FLOW
The information flow between BIM and BEM is unidirectional from BIM
applications toward energy simulation applications. The designer creates her/his

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model in the BIM application and when she/he wants to analyze how the design
performs regarding the energy efficiency she/he prepares the model for the export.
The exported model is imported in energy simulation application, missing data is
added to create valid BEM model. After the required calculations are performed the
results remain connected to the BEM model. Even if energy simulation application
provides mapping of the results on the building model, that mapping is performed
against simplified BEM model.
The designer who wishes to design energy efficient building is forced to base
her/his decisions on the interpretation of the BEM model. If designer tries to do that
by himself, she/he he falls into the trap of false understanding of results. Result
obtained with different applications or with different version of the same application
shows considerable variation [5]. The understanding of the results requires detailed
knowledge of particular energy simulation application that only proper expert can
have. Unfortunately, these people are specialized in their field and they can give
excellent recommendation how to improve BEM model to achieve better results, or
how to improve BIM model to get more accurate BEM model. The designer does not
receive any feedback from BEM model how to improve her/his design to achieve
more energy efficient building. He can not get any information how to improve
building‟s form, how to select more appropriate building components or how to
design efficient building systems. All these decisions are still based on designer‟s
experience and intuition.

5. MODEL INFORMED ENERGY EFFICIENCY DESIGN

We can conclude that at the current level of technology development applications
are using models to achieve final results like consistent building plans, coordinated
technical documentation, effective rendering or precise simulation of building energy
consumption. The model per se is not treated as an important component of the whole
process. This fact is confusing in the time when majority of engineering branches
embrace model as the essential building block of their profession. Perhaps the reason
lies in the fact that in the AEC, especially in architecture, the model is identified with
the mock-up.
In the initial stage of popularization of BIM technology computer generated
building model was seen as the core around which all applications gather and every
one believed that interoperability formats will provide the appropriate support. But
reality denied that initial optimism. On the other hand, as the paper shows, greater
reliance on computer model of the building is necessary if we want to achieve better
energy efficiency design.
The first step toward model informed energy efficiency design is change of
designer‟s habits. Greater effort must be invested in the education of designers and a
better understanding of the term “model” should be achieved. The computer based
building model should be regarded as an essential source of information which
underlies all design decisions. We don‟t need to develop some new overarching

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theoretical construct that will again led to overoptimistic expectations, instead we

should use existing information resources and technologies and enhance its value by
creating better interconnection. Also, the list of useful applications should be
expanded to include programs like SketchUp and other light BIM applications.
Attention should also be paid to the so-called BIM explorers or viewers, like BIMx,
Tekla BIMsight, DDS-CAD Viewer, etc.
The first step toward model informed energy efficiency design is thorough
analysis how each design application interacts with each energy simulation
application, and special attention should be paid to free energy simulation software
that often offers excellent simulation algorithms but lack in compatibility with other
programs. This should led to better understanding of what information is needed by
energy simulation applications, how is that information handled by existing
interoperability formats, and finally, how that information is incorporated in
components that design applications (BIM or light BIM) uses to construct their
models.
Once detailed understanding of information needs is achieved the next step will be
the development of software tools that that connect various files and applications and
inform the designer to how achieve optimal connectivity. The technology most suited
for that task has already been developed as the part of the semantic net project [7]. It
compromises of the layers of standardized technologies that allow addition of the
meaning to basic information. Using this technology it will be possible to develop a
knowledge bases that will improve the use of BIM tools and provide feedback that
will help the designer to develop more efficient solutions. Also, new developments in
the field of building information interoperability, like IFC4 Design Transfer View
will add increase the efficiency of data exchange between applications and lead to
even simple creation and use of computer based building model.

6. CONCLUSION
Computer software like BIM applications coupled with energy simulation
applications have great potential to improve energy efficient design despite current
problems. The existing technology already has potential to achieve that goal, what is
now required is greater involvement of designers in that endeavor that will led to
better understanding of technologies and more informed requirements toward
technology improvements that will persuade software developers to enhance their
products.

ACKNOWLEDGEMENT
This work was supported by the Ministry of Education, Science and Technological
Development of the Republic of Serbia under grant TR-36038. It is a part of the
project „Development of the method for the production of MEP design and
construction documents compatible with BIM process and related standards.‟ The
project director is dr Igor Svetel.

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REFERENCES
[1] gbXML, http://www.gbxml.org/, accessed 15th Oct 2015.
[2] IFC, (2013) Industry Foundation Classes Release 4 (IFC4),
http://www.buildingsmart-tech.org/ifc/IFC4/final/html/index.htm, accessed 15th
Oct 2015.
[3] IFC2x3 CV V2.0 (2013) Coordination View Version 2.0,
http://www.buildingsmart-tech.org/specifications/ifc-view-definition/
coordination-view-v2.0, accessed 15th Oct 2015.
[4] ISO, 2013 Industry Foundation Classes (IFC) for data sharing in the construction
and facility management industries, http://www.iso.org/iso/ catalogue_detail.htm
?csnumber=51622, accessed 15th Oct 2015.
[5] Jarić, M., Budimir, N., Svetel, I., 2015, Predicting Energy Consumption Using
Current BIM Software, in Spasojević-Brkić, V., Misita, M., Milanović, D.D.,
(eds.) 6th International Symposium on Industrial Engineering - Sie2015,
Proceedings. Beograd, Faculty of Mechanical Engineering: pp. 287-290.
[6] Jarić, M., Budimir, N., Svetel, I., 2015, Preparing BIM Model for Energy
Consumption Simulation, in Spasojević-Brkić, V., Misita, M., Milanović, D.D.,
(eds.) 6th International Symposium on Industrial Engineering - Sie2015,
Proceedings. Beograd, Faculty of Mechanical Engineering: pp. 291-294.
[7] Svetel, I., Pejanović, M., 2010, The Role of the Semantic Web for Knowledge
Management in the Construction Industry, Informatica 34: pp. 331–336

[618]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 502.171:620.9
1
Norbert HARMATI
Ţeljko JAKŠIĆ2
Radomir FOLIĆ3
Jasmina DRAŢIĆ4

ENERGY PERFORMANCE SIMULATION IN OFFICE BUILDINGS

EQUIPED WITH HEAT PUMP SYSTEM
Abstract: This paper presents a detailed analysis of an energy model and outlines the significance and
influence of design and construction on the overall energy consumption. The parameters of the building
envelope, heat pump system, user comfort, schedules and occupancy are implemented into the energy
model. The building model is constructed according to the rules of energy efficiency to analyze and
evaluate the overall energy consumption on an annual basis. The research was conducted with
EnergyPlus dynamic simulation which allows flexibility of the thermal model, resulting in an energy
simulation to outline the major criteria in qualitative enhancement. The paper presents the energy
performance of heat pump system with determination of the system’s energy requirements.

Кey words: Building energy simulation, energy performance, multi-zone thermal model
.

SIMULACIJA ENERGETSKE PERFORMANSE POSLOVNE

ZGRADE OPREMLJENE SISTEMOM TOPLOTNE PUMPE
Rezime: Rad predstavlja detaljnu analizu energetskog modela i utvrđuje energetsku potrošnju poslovne
zgrade koja je opremljena toplotnom pumpom. Parametri omotača zgrade, parametri komfora, raspored i
zauzetosti su implementirani u energetski model. Model je konstruisan prema pravilniku o energetskoj
efikasnosti za analizu i procenu sveukupnih energetskih zahteva na na godišnjem nivou. Istraţivanje je
sprovedeno putem nergyPlus dinamičke simula ije koji omogu ava fleksi ilnost termičkog modela i
varija ilnost svojstava elemenata, uz pomo kojih je mogu e oderediti osnovne kriterijume
za formulisanje kvalitetnog rešenja. U radu prikazana je energetska performansa sistema toplotne pumpe
i takođe je određen i energetski zahtev samog sistema.

Ključne reči: Energetska simulacija zgrada, energetska performansa, multi-zonski termički model.

1
Ass. D.Sc., University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,
e-mail: harmati@uns.ac.rs
2 Ass. Prof. Dr., University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,

e-mail: alt96@uns.ac.rs
3 Prof. Dr., University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,

e-mail: r.folic@gmail.com
4
Full-Prof.Dr., University of Novi Sad, Faculty of Technical Sciences, Department of Civil Engineering and Geodesy,
e-mail: dramina@uns.ac.rs

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1. INTRODUCTION
A great amount of world energy demand is connected to the built environment.
The connection between the increased CO2 discharge to the atmosphere and the use of
energy is also a motive to render a more efficient energy usage, and lowering the total
energy demand [1]. Electricity, heating, cooling and ventilation account one third of
total energy consumption in office buildings. Therefore, the goal is finding an
alternative solution in order to reduce the energy demand and losses. Numerous
researches have been devoted in order to investigate the energy performance of
buildings in the commercial sector.[2,3] Building energy efficiency and building
performance topics were elaborated via investigations of existing office buildings and
computational building models respectively.
Simulation-based building performance allows detailed assessment of energy
consumption in buildings, to analyze the energy performance. We can examine the
influence of each factor extensively and systematically utilizing a dynamic energy
simulation tool such as EnergyPlus®, which allows flexibility of the energy model and
variability of the construction elements, material properties, lights, HVAC system and
occupants.
The parametric model was developed according to the standards of designing
office work spaces, accessories and communication. The parameters of user comfort
are implemented from the weather data with the location: Belgrade, Serbia. The
results of the energy simulation outline major criteria for qualitative enhancement.
The investigation concerns the following objectives:
 Modeling a basic medium office building according to the functional disposition
of office work spaces
 Implementation of weather data, location data, construction sets and materials,
schedules for operation of lighting, HVAC, and occupancy
 Performing an annual energy simulation, 8760 hours
 Evaluation of the HVAC system influence on the total annual energy
consumption and testing the efficiency of the Heat Recovery system

2. ENERGY MODEL
The energy model is constructed as a medium office building consisting of 8
offices, entrance, hall and WC, shown in table 1. The climate and location data were
used from the weather file of the US Department of Energy [4]. The location of the
following building model is Belgrade, Serbia.

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Table 1 – Multi-zone model spaces

Space Area [m2] Volume [m3] Space Area [m2] Volume [m3]
Office 1 48,27 168,95 Office 6 16,53 57,85
Office 2 48,27 168,95 Office 7 16,53 57,85
Office 3 48,27 168,95 Office 8 16,53 57,85
Office 4 16,53 57,85 Entr.,hall 60,00 210,0
Office 5 16,53 57,85 WC 12,50 43,75
2 3
Area Sum [m ] 300,00 Volume Sum [m ] 1050,00

The setup of the parametric model was performed in Open Studio1.0.0 and
EnergyPlus 7.2 program. [5,6] The building elements, HVAC system, occupants,
electric equipment, lighting and schedule sets form the input data for the energy
simulation. EnergyPlus requires spaces to be transformed into thermal zones in order
to define the properties necessary for the calculation of the energy loads. Building
loads are a complex topic because there are many interrelated terms to navigate.
Energy loads can be divided into:
1. Thermal loads (the heat energy that needs to be added to or removed to
maintain thermal equilibrium, sensible heat, and control moisture, latent heat,
for occupant comfort)
a. Heating loads
b. Cooling loads
2. Internal loads (People, equipment, lighting)
3. External loads (Sun, air, moisture)
4. Equipment loads
a. HVAC
b. Plug Loads
c. Lighting Loads
2.1. Schedules and construction
The thermostat schedules were calibrated to the following, table 2.
Table 2 - Thermostat schedules
Schedule Date Time Temperature limit
Office Cooling Setup Schedule 01.05 – 30.09 Mo. To Fri. 7-18h 24 0C
Office Heating Setup Schedule 01.10 – 30.04 Mo. To Fri. 7-18h 21 0C

The schedules for the operation of the building equipment, interior lights and
occupants were also set up for the date, time and scale of the function.
For the construction the ASHRAE 189.1 Climate zone 7-8 Construction Set was
used. The elements which were modified in the exterior surface construction are the
exterior walls, while in the sub-surface construction double layer technical glass was

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applied for the windows. The layers for the new construction elements are shown in
table 3, and the surface properties are shown in table 4.
Table 3 - Modified construction set properties
Exterior wall Properties Windows Properties
d = 0,1016m Solar transmittance 0.4296
c = 0,89 W/mK Solar reflectance 0.5204
100 mm brick 6 mm glass panel
ρ = 1920kg/m3 Visible transmittance 0.4503
Q = 790 J/kgK Conductivity 0.0089 W/mK
d = 0,1016m
c = 0,03 W/mK
100 mm insulation 13 mm gap d = 0,0127m
ρ = 43 kg/m3
Q = 1210 J/kgK
d = 0,20m
200 mm concrete c = 1,11 W/mK
block ρ = 800kg/m3
Q = 920 J/kgK Solar transmittance 0.4296
19 mm wall air space D = 0,019 m Solar reflectance 0.5204
6 mm glass panel
resistance R = 0,15 m2K/W Visible transmittance 0.4503
d = 0,19m Conductivity 0.0089W/mK
c = 0,16 W/mK
19 mm gypsum board
ρ = 800kg/m3
Q = 1090 J/kgK

Table 4 - Surface properties

U-Factor with U-Factor no
Construction Reflectance
Film [W/m2-K] Film [W/m2-K]
Exterior wall 0.30 0.244 0.253
Ground floor slab 0.30 1.627 2.692
Roof 0.30 0.156 0.160
SURFACE
Glass U-Factor Glass Visible
Window (Double- Glass SHGC
[W/m2-K] Transmittance
layer)
0.80 0.290 0.271

The building envelope and window to wall ratio is shown in table 5.

Table 5 -Window-, wall-area and window-wall ratio
North (315 East (45 to South (135 West (225 to 315
Total
to 45 deg) 135 deg) to 225 deg) deg)
264.8
Gross Wall Area [m2] 84.00 48.40 84.00 48.40
0
Window Opening
88.19 25.20 14.52 33.95 14.52
Area[m2]
Window-Wall Ratio [%] 33.30 30.00 30.00 40.42 30.00

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2.2. Multi thermal zones

Four thermal zones were formed for the analysis. Two zones are formed from
offices, the first from large- the second from small offices, the third zone is the WC
and the fourth is the main entrance with hall. Each zone has its loads from the heating
and cooling system, equipment, occupants, and lights. The schedules applied for the
zones have to maintain the comfort of users which refers to the temperature,
humidity, illumination, air quality and airflow rate inside the building.
2.3. Heat pump system
Rooftop Heat Pump has been used for the whole complex to examine the annual
energy performance. Thermal zone 1 is the control zone for the building. The HVAC
system consists of supply and demand equipments, which are the following, table 6.

Table 6- HVAC system elements

1. Coil cooling dx single speed
2. Coil heating dx single speed
Supply
3. Coil heating electric
equipment
4. Variable speed fan
5. Setpoint manager single zone reheat
1. Zone 1 Air terminal single duct VAV with electric reheat
Demand 2. Zone 2 Air terminal single duct VAV with electric reheat
equipment 3. Zone 3 Air terminal single duct VAV with electric reheat
4. Zone 4 Air terminal single duct VAV with electric reheat

3. ENERGY SIMULATION AND RESULTS

The simulation was performed for a period of one year, 8760 hours with 1
timestep calculation per hour. The obtained results are the following, Fig.1. The
electricity consumption was calculated for heating, cooling, fans, interior lighting and
equipment.

5.0
Electricity [GJ]

4.0
3.0
2.0
1.0
-

INTERIORLIGHTS:ELECTRICITY [J] INTERIOREQUIPMENT:ELECTRICITY [J]

FANS:ELECTRICITY [J] HEATING:ELECTRICITY [J]
COOLING:ELECTRICITY [J]

Figure 1 - Building Energy Performance – Electricity

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The total energy consumption for the buildings is 10930 kWh/yr. The factor of
conversion from total energy into primary energy equals f prime = 3,5 which results in
38255 kWh/yr of primary energy demand, which means that the building requires
127,51kWh/m2/yr. The heating and cooling loads equal 24566 kWh/yr which is 64,21
% of the total energy requirement. The electricity requirement for the lighting,
operation of HVAC requires the following amount of electricity, table 7.

Table 7- Annual electricity demand

Interior Fans:
Interior lights: Heating: Cooling:
equipment:
electricity [J] electricity [J] electricity [J] electricity [J]
electricity [J]

January 288,851,000 614,172,000 398,370,000 4,657,410,000 0

February 259,563,000 558,036,000 294,036,000 3,305,520,000 0

March 284,216,000 619,514,000 273,185,000 2,191,210,000 0

April 281,460,000 601,823,000 247,351,000 943,663,000 6,661,277

May 280,659,000 609,969,000 255,831,000 572,573,000 460,209,000

June 281,460,000 601,823,000 249,991,000 341,179,000 760,878,000

July 292,409,000 623,717,000 260,912,000 279,563,000 1,102,130,000

August 280,659,000 609,969,000 259,790,000 281,243,000 978,054,000

September 281,460,000 601,823,000 248,258,000 491,260,000 306,853,000

October 288,851,000 614,172,000 259,463,000 1,181,370,000 24,365,907

November 273,268,000 597,620,000 278,073,000 2,508,550,000 0

December 292,409,000 623,717,000 428,937,000 4,843,900,000 0

Ann. sum 3,385,260,000 7,276,360,000 3,454,200,000 21,597,400,000 3,639,150,000

Min. 259,563,000 558,036,000 247,351,000 279,563,000 0

Max. 292,409,000 623,717,000 428,937,000 4,843,900,000 1,102,130,000

The obtained results show that the parametric model was designed in order to
result in reasonable energy performance. Yet no Heat Recovery has been added to the
HVAC system. To simulate the energy consumption and to obtain the efficiency of
the Heat Recovery – Heat Exchanger the unit was connected to the Air Loop Outdoor
Air System. The Rotary heat exchange is show in Fig. 2. The properties of the
applied Heat Exchanger (air to air) are shown in table 8.

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Figure 2 – Rotary Heat Exchanger

Table 8 - Heat Exchanger air to air sensible and latent

Supply air flow rate Autosized
Sensible effectiveness at 75% heating air flow 0,81
Latent effectiveness at 75% heating air flow 0.73
Sensible effectiveness at 75% cooling air flow 0,82
Latent effectiveness at 75% cooling air flow 0,73
Heat Exchanger type Rotary

The exact simulation with the Heat Exchanger shows different results. The annual
energy demand is shown in Fig. 3.

3.0
2.5
Electricity [GJ]

2.0
1.5
1.0
0.5
-

INTERIORLIGHTS:ELECTRICITY [J] INTERIOREQUIPMENT:ELECTRICITY [J]

FANS:ELECTRICITY [J] HEATING:ELECTRICITY [J]
COOLING:ELECTRICITY [J]

Figure 3 - Building Energy Performance - Electricity

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The total energy consumption for the buildings is 7529 kWh/yr. The factor of
conversion from total energy into primary energy equals f prime = 3,5 which results in
26351 kWh/yr of primary energy demand, which means that the building requires
87,83 kWh/m2/yr. The heating and cooling loads equal 12785 kWh/yr which is 48,51
% of the total energy requirement. The electricity requirement for the lighting,
operation of HVAC requires the following amount of electricity, table 9.

Table 9 - Annual electricity demand

Interior Cooling:
Interior lights: Fans: Heating:
equipment: electricity
electricity [J] electricity [J] electricity [J]
electricity [J] [J]

January 288,851,000 614,172,000 346,882,000 2,424,050,000 0

February 259,563,000 558,036,000 267,939,000 1,537,360,000 0

March 284,216,000 619,514,000 262,185,000 744,455,000 0

April 281,460,000 601,823,000 247,351,000 255,432,000 1,925,429

May 280,659,000 609,969,000 257,110,000 154,887,000 460,320,000

June 281,460,000 601,823,000 250,741,000 92,350,562 718,469,000

July 292,409,000 623,717,000 262,953,000 80,060,151 986,266,000

August 280,659,000 609,969,000 262,064,000 80,793,331 868,000,000

September 281,460,000 601,823,000 249,898,000 134,058,000 313,865,000

October 288,851,000 614,172,000 256,590,000 376,151,000 7,121,969

November 273,268,000 597,620,000 263,632,000 1,079,420,000 0

December 292,409,000 623,717,000 362,675,000 2,838,130,000 0

3,355,970,0
Ann. sum 3,385,260,000 7,276,360,000 3,290,020,000 9,797,150,000
00
Min. 259,563,000 558,036,000 247,351,000 80,060,151 0
Max. 292,409,000 623,717,000 362,675,000 2,838,130,000 986,266,000

Comparison among the HVAC system electricity intensity is shown in table 10,
without and with the application of the heat recovery.

Table 10 – Annual utility use per total floor area

Without Heat Recovery With Heat Recovery
2
HVAC Electricity 97,79 MJ/m /yr HVAC Electricity 56,05 MJ/m2/yr
Intensity 27,16 kWh/m2/yr Intensity 15,56 kWh/m2/yr

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4. CONCLUSION
Building energy simulation presents a potential overview of the energy
performance in buildings and gives a greater understanding of the energy
consumption in each sector. With calibration of the model properties and mechanical
systems it is possible with professional intervention to reduce the energy demand or
to direct the requirements to an alternative sector where necessary.
It was concluded that an office building equipped with heat pump system would
require for heating and cooling 12785 kWh annually which is 48,51 % of the overall
energy requirement. Whereas the electricity intensity of the heat pump system used
both for heating and cooling resulted in 15,56 kWh/m2 on an annual basis.

ACKNOWLEDGMENT
The work reported in this paper is a part of the investigation within the research
projects III42012 supported by the Ministry for Science and Technology, Republic of
Serbia.
This paper is a part of the research that is performed within the project
“Development and appli ation of ontemporary procedures for design, construction
and maintenan e of uildings” founded y the University of Novi Sad, Fa ulty of
Technical Sciences, Department of Civil Engineering and Geodesy in 2015.

REFERENCES
[1] Eskin, N, Türkmen, H. 2008. Analysis of annual heating and cooling energy
requirements for office buildings in different climates in Turkey. Energy and
Buildings 40: 763–773. doi:10.1016/j.enbuild.2007.05.008
[2] Sartori, I, Hestnes, AG. 2007. Energy use in the life cycle of conventional and
low-energy buildings: A review article. Energy and Buildings 39: 249–257.
doi:10.1016/j.enbuild.2006.07.001
[3] Fumo, N, Mago, P, Luck, R. 2010 Methodology to estimate building energy
consumption using EnergyPlus Benchmark Models, Energy and Buildings 42:
2331–2337. doi:10.1016/j.enbuild.2010.07.027
[4] EnergyPlus Weather file, http://apps1.eere.energy.gov/
[5] OpenStudio, National Renewable Energy Laboratory, http://openstudio.nrel.gov/
[6] EnergyPlus,
http://apps1.eere.energy.gov/buildings/energyplus/?utm_source=EnergyPlus&utm
_ medium=redirect&utm_campaign=EnergyPlus%2Bredirect%2B1

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DISASTER RISK MANAGEMENT
AND FIRE SAFETY
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 005.334:504
1
Senka BAJIĆ
Mirjana LABAN2
Jovana SIMIĆ3
Vukašin KUKIĆ4

FIRE RISK ASSESSMENT FOR SPORTS AND BUSINESS CENTER

BEOČIN
Abstract: Public buildings, in which a large number of people gather, are often high-risk buildings in
case of fire. The multi-purpose facilities, such as Sports and Business Center Beočin, require detailed
analysis of the evacuation. In the survey, the main hall and the risk zones within it were identified. The
research provides an analysis of the evacuation scenario, focusing on the evacuation routes and the
required evacuation time. The purpose of the fire risk assessment is reducing the risk to human life to a
minimum level, and if the fire in the building happens, that the consequences are negligible. Based on the
research results, recommendations for reducing the occurrence of fire in buildings and improvement of
the fire safety were proposed, especially in sports and business centers, such as analyzed center in
Beočin.

Кey words: Risk, Fire, Buildings, Risk assessment, Evacuation.

PROCENA RIZIKA OD POŽARA ZA SPORTSKO-POSLOVNI

CENTAR BEOČIN
Rezime: Javne zgrade, u kojima se okuplja veliki broj ljudi često predstavljaju zgrade visokog rizika u
slučaju požara. U višenamenskim objektima, kao što je Sportski i poslovni centar Beočin, su potrebne
detaljne analize mogućnosti evakuacije. Istraživanjem je obuhvaćena glavna sala i identifikovane su zone
rizika unutar nje. Analiziran je evakuacioni scenario, koji se fokusira na evakuacione puteve i potrebno
vremena za evakuaciju. Svrha procene rizika od požara je svođenje rizika po živote ljudi na minimum, a
u slučaju da se požar dogodi, da su posledice zanemarljive. Na osnovu rezultata istraživanja predložene
su preporuke za smanjenje pojave požara u zgradama i unapređenje bezbednosti od požara, posebno u
sportskim i poslovnim centrima, kao što je analizirani centar u Beočinu.

Ključne reči: Rizik, požar, zgrada, procena rizika, evakuacija.

1
PhD student, Faculty of technical sciences Trg Dositeja Obradovica 6, senka.bajic@gmail.com
2
Assistant professor, Faculty of technical sciences Trg Dositeja Obradovica 6, mlaban@uns.ac.rs
3
Teaching Assistant, Faculty of technical sciences Trg Dositeja Obradovica 6, jovanassimic@gmail.com
4
Student- Master studies, Faculty of technical sciences Trg Dositeja Obradovica 6, vukasin.kukic92@gmail.com

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1. INTRODUCTION
Causes of fires in buildings are different, but in the most cases they are caused by
human error or negligence [1]. Fires that happen in buildings can cause many
casualties which can affect people in many ways. Fire as a hazardous event, however,
can only happen if the fire prevention measures fail [2]. For improvement of fire
safety and protection systems, it is required explicit consideration of multiple fire
scenarios, response of building fire safety systems and human behavioral responses
[3]. Fires in buildings have become a serious problem in many countries and each
year negative impact is increasing, ecpecially on humans, society, economy and
ecology.
Over the years, there have been many deadly night club fires, and fires in large
public buildings, in the world [2]. Today, many large public buildings which were
built for one purpose are used for many other purposes. In the last decade numerious
fire accidents occurred in the gyms and sports ceneters [4,5,6,7,8]. Sports and
Business Center Beočin is the only facility of that kind in the municipality. Therefore,
large number of sports and cultural events are held in Sports and Business Center
Beočin with great number of people, which sometimes exceed allowed maximum.
Furthermore, a great number of visitors can be affected by fire. Finally, risk
assessment, mainly focusing on evacuation route selection and estimation of required
evacuation time, is inevitable.
Some of the well known fires that happend in Sports and business centers are:
 Ignition occured in the Sports Hall "Red Star" in Belgrade on the 5 of April
th

2008, due to poor electrical installations. The building was totally destroyed [4].
 Fire occured in the sports hall in Mescu, near Subotica on the 24 of August
th

2009, also due to poor installation. The roof structure, and the handball court and
hall floors were completely destroyed. Fire Department evacuated the present
staff [5].
 Large fire broke out in the sports center in Copenhagen on the 28 of September
th

2011, which destroyed the whole building. Three people were transported to the
hospital [6].
 Fire occured at the tennis championship "Wimbldon" on the 1 of July 2015, due
st

to the overheating of the motor and lower failure on installations. Three thousand
people were evacuated, while one person was lightly injured [7].
 A small fire occured in the sports hall in Brandenburg near Berlin on the 24 of
th

August 2015. The building was the temporary accommodation of refugees.

There were only minor damage, while the rescue team intervened rapidly [8].
In Sports and Business Center Beočin, on the 19th of April 2014. was a fire
incident. In the boiler room, the heater overheated and the smoke spreaded extreamly
quicky. Soon the situation became more serious and lead to inflammation. Fire units
reacted in time and extinguished the fire. Only miner damage was caused.

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2. FIRE RISK ASSESSMENT AND EVACUATION CHARACTERISTICS

The term fire risk assessment refers to assessing risks to both people and property
as a consequence of unwanted fires. There are two types of risk assessment, simple
and comprehensive. In a simple risk assessment certain fire scenario is considered,
while in a comprehensive risk assessment all probable unwanted scenarios are taken
into account [2].
A fire scenario involves the projection of a set of fire events, all of which are
linked together by whether the fire protection measures succeed or fail. The
consequence of a fire scenario can be assessed by using time-dependent modeling of
fire and smoke spread, occupant evacuation and fire department response [2].
A fire’s development in a compartment can endanger occupants and properties in
the compartment of fire origin, but also can easily spread in other parts of the
building. The occupants’ safety depends on their timely evacuation to a place of
safety, whether it is a safe area inside the building or an open space outside the
building. Evacuation time includes detection and warning time, delay start time and
movement time [2].
The time duration from ignition in the compartment of fire origin to the
appearance of the critical smoke conditions in the evacuation routes that hinder
evacuation is called the available evacuation time, also called the available safe
egress time (ASET). The time duration from ignition in the compartment of fire
origin to the time required for the evacuation of all of the occupants is called the
required evacuation time, also called the required safe egress time (RSET). The aim
of safe evacuation is to have the required evacuation time less than the available
evacuation time [2].

Required evacuation time < available evacuation time.

Calculation of different evacuation characteristics is needed for estimation of the

evacuation time and transience through the passage corridor for the evacuation.
According to technical recommendations, movement speed of a man is: V = 1.5 m/s.
The speed of movement during evacuation is reduced due to grouping of people from
the narrowing of the corridor (doors, etc.), turning corridors, staircases etc. Speed of
movement is calculated like product of unimpeded speed and the factors which are
slowing the movement [9]. While crossing a narrowing of the corridor or door
openings that are less than 1.00 m for 10 to 40 people, or door openings of less than
1.60 m for 40 to 200 people, anticipated dwell time is 3 seconds for every 10 persons.
For each turn with an angle greater than 60 ° and encountering stairs or ramp, dwell
time is 2 seconds for every 10 persons. For each turn with an angle greater than 60 °
and confronting the escalator in motion, an additional 5 seconds for every 10 persons
is needed [9]. Evacuation routes should be short enough so that evacuation can be
conducted without any long and direct exposure of a person to the smoke and fire.

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3. CASE STUDY- ESTIMATION OF REQUIRED EVACUATION TIME IN

SPORTS AND BUSINESS CENTER BEOČIN
Sports and Business Center Beočin is located at the eastern part of the settlement
Beočin, which is 11.73 km far from Novi Sad. Building is on sufficient distant from
the neighboring buildings, so there is no possibility of direct transfer of the fire from
one building to another.
The main purpose of Sports and Business Center Beočin is provision of adequate
hall for trainings and sports games (basketball, handball, volleyball, football, etc.) and
also other sports such as table tennis, judo, karate, boxing and etc. Dimensions of the
building form a rectangle (59.80 m x 64.80 m), with a centrally positioned main hall,
around which are symmetrically located, on three different sides, other rooms, and the
fourth side (west) is a direct exit from the arena. Sports and Business Center Beočin is
one story building [10].
The building consists of five functional units, which are interconnected:
 Main arena,
 Space for athletes,
 Space for visitors
 Bleachers,
 Complementary facilities.
Main hall consists of one main arena and bleachers. Dimensions of the main hall
are 45 m x 26.60 m, on the longer side (east – west) of the building. Height of hall
ranges from 9.20 m (min.) - 11.60 m (max.) from the ending of the floor all the way
to the first obstacles (lattice) [10]. Bleachers consist of 9 rows of seats. The maximum
capacity of the bleachers is 585 seats, and additional 200 standing places. The main
hall has 7 evacuation exits. Direct exit from the main arena is provided over a gate
with width of 2 x 320 cm, which is also an entrance for vehicles in the event of
intervention. In the bleachers there are two exits in the foothills, while there are also
two on the first floor or the top of the bleachers. All four exits lead to the main exit
/entrance to the building which is composed of two double doors of 193cm.
For the purpose of the study, evacuation time for scenario where there is concert
event in the main hall of Sports and Business Center Beočin with 1,700 visitors is
calculated, mainly focusing on evacuation from the main arena (Figure 1). Evacuation
is divided into separate exits to avoid crowd and to unburden the main entrance/exit
from the building. On the Figure 2. the suggested schedule and the number of people
who will be evacuated through the evacuation exits, is shown (Figure 2).
It is determined that 450 people from the part B of the arena, will evacuate through
the main exit. Other 350 people from the part C of the arena will evacuate via left exit
on the north side of the building, and people from part D of the arena (350 people)
will evacuate over the right exit on the north side of the building. Around 200 people
from the part A of the arena, will evacuate through the left exit on the south side of
the arena and people from part E of the arena (350 people) will evacuate through the
right exit on the south side of the arena. For calculation of evacuation time in this

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scenario, suggestions given in Technical recommendations for fire protection of

residential, commercial and public buildings were used [9].

Figure 1: Main arena Figure 2: Method of evacuation

The first stage of evacuation (part A of the area)

The first stage of the evacuation of A part of the arena includes time needed to get
from starting point (PM), to first exit (PI), specifically left exit on the south side of
the arena. Total time required for the evacuation of part A of the arena is 183,2 s
which is less than available time of 240 s, therefore evacuation can be processed
safely (Figure 3).

Figure 3: Evacuation route for A part of the arena

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The first stage of evacuation (part E of the arena)

The first stage of evacuation for the E part of the arena includes time needed to get
from starting point (PM), to first exit (PI), exactly the left exit on the south side of the
arena. Calculations have shown that required time for evacuation of part E of the
arena is 302 s which is greater than available time of 240 s, thus evacuation route is
not safe (Figure 4).
The first stage of evacuation (part B of the arena)
The first stage of the evacuation of B part of the arena includes the time needed to
walk from the farthest point (PM) to exit of arena (KI). Total time required for the
evacuation of part B of the arena is 84,2 s which is less than available time, hence
evacuation route is safe (Figure 5).

Figure 4: Evacuation route for E part of the Figure 5: Evacuation route for B part of the
arena arena

The first stage of evacuation (part C of the arena)

The first stage of the evacuation of C part of the arena includes time needed from
starting point (PM), to first exit (PI), particularly, the left exit on the north side of the
arena. Calculations have shown that required time for evacuation of part C of the
arena is 122,5 s which is less than available time, accordingly evacuation can be
processed safely (Figure 6).
The first stage of evacuation (part D of the arena)
The first stage of evacuation of the D part of the arena includes time needed to get
from starting point (PM), to first exit (PI), particularly the right exit on the north side
of the arena. Calculations have shown that required time for evacuation of part D of
the arena is 120, 9 s which is less than available time, thus evacuation route is safe
(Figure 7).

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Figure 6: Evacuation route for C part of the Figure 7: Evacuation route for D part of the
arena arena

The second stage of evacuation (part C and part D of the arena)

The second stage of evacuation for the C part of the arena includes the period of
time needed from the PI, first exit corridor, then turning to the left and coming to KI,
final exit, where they meet with the persons evacuated from D part. The second stage
of evacuation for the D part of the arena includes the period of time needed to get
from the PI, first exit corridor, then to the right to the door, after which goes turn to
the left and moving down the hall, which leads to KI, final exit, where persons meet
with people evacuated from C part (Figure 6 and Figure 7).
It is shown that time needed for second stage of evacuation is longer (723,33 s)
than available evacuation time, which is 60s. Furthermore, evacuation cannot be
processed safely. The third stage of the evacuation doesn’t exist, while the fourth
stage of evacuation include movement from KI, final exit to safety location on the
northeast side, just 30 meters from the building.
The second stage of evacuation (part A and part E of the arena)
The second stage of evacuation for the part A and part E of the arena includes the
time needed from the PI, first exit, then to the left or right to the stairs, then
movement to the main entrance where they meet with the persons who are evacuated
from the bleachers (Figure 3 and Figure 4). Calculations have shown that required
time for second stage of evacuation of the part A and the part E of the arena is greater
(968 s) than available time of 60 s, consequently evacuation route is not safe. The
third stage of the evacuation doesn’t exist, while the fourth stage of evacuation
includes the movement from the KI, final exit, to the safety location on the southwest
side, which is 30 meters from the building.

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4. RESULTS
After calculating the total evacuation time with preparation for every part of the
arena, the results showed that use of main hall for event with high concentration of
people can have effect on safety of the people who are attending the event. According
to the Elaborate of fire protection maximum number of people who can attend the
event and who will evacuate safely is 2500, while our calculations have shown
differently [10,11]. Due to the size and proximity of the main entrance of the main
hall, according to the calculations, it is planned that only people from the B part of the
arena (450) will evacuate safely. For the evacuation of persons through exits on the
north side of the arena, evacuation time significantly exceed prescribed standards and
available time for safe evacuation. An aggravating circumstance is that a large
number of dressing rooms are often locked on one side, which can slow down the
process of evacuation. People who are coming out of the building through exit on the
south side of the arena could meet with the people who evacuated from the bleachers,
thus a crowd can be created. These people could also meet additional obstacles in the
corridors, which can be fatal. A large concentration of people creates the rush which
can cause blockage of main exit. For evacuation of people with disabilities left exit on
the south side is planned, which is very often congested with obstacles in the form of
goals, chairs and other objects. According to the final result of risk analysis during
evacuation in given scenario, limited capacity of visitors during events has to be taken
with extra caution and attention. It is recommended that calculations of maximum
number of persons, who would attend large events, should be done and limit the
number of visitors below the calculated maximum. Research results suggest opening
of two new alternative exits which can reduce evacuation time and fire risk and
improve fire safety measures (Figure 8).

Figure 8: Current exits and new alternative exits

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5. CONCLUSION
The population does not attach great importance and do not pay enough attention
to fire as a hazard. Only after the events, human consciousness notes that it is very
important to be familiar with the rules and procedures in a case of fire. Regular
evacuation training and drills are extremely important and can be an obligatory
requirement in different fire safety scenarios which can lead to tragic consequences.
Fire risk assessment and calculation of evacuation times and selection of controlled
evacuation routes are of major importance for reduction of the incidence of fire, and
first of all, could contribute to the minimization of human and material casualties.

ACKNOWLEDGMENTS
The work reported in this paper is a part of the investigation within the research
project „Development and application of contemporary procedures for design,
construction and maintenance of buildings“ supported by the Department for Civil
Engineering and Geodesy, Faculty of Technical Sciences in Novi Sad. This support is
gratefully acknowledged.

REFERENCES
[1] Sakulski, D. et al., 2012. Skripta: Upravljanje akcidentnim rizicima. Novi Sad:
Fakultet tehničkih nauka.
[2] Yung, David 2008. Principles of fire risk assessment in buildings. Toronto: John
Wiley & Sons, Ltd.
[3] Hasofer A. M., Beck V. R., Bennetts I. D. 2007. Risk Analysis in Building Fire
Safety Engineering. Oxford: Elseiver.
[4] Izbegnuta katastrofa. (n.d.), available at: http://www.naslovi.net/2008-04-
06/glas-javnosti/izbegnuta-katastrofa/630155, visited 5th October 2015.
[5] Gorela nova sportska hala u MEŠC-u. (n.d.), available at:
http://www.subotica.info/2009/08/23/gorela-nova-sportska-hala-u-mesc-u,
visited 5th October 2015.
[6] Sportska arena u Kopenhagenu uništena u požaru. (n.d.), available at:
http://www.blic.rs/Vesti/Svet/279728/Sportska-arena-u-Kopenhagenu-unistena-
u-pozaru, visited 5th October 2015.
[7] VIMBLDON: Požar na centralnom terenu, evakuisano na hiljade ljudi. (n.d.),
available at: http://volimpodgoricu.me/2015/07/02/vimbldon-pozar-na-
centralnom-terenu-evakuisano-na-hiljade-ljudi/, visited 5th October 2015.
[8] Požar u budućem izbegličkom centru u Nemačkoj. (n.d.), available at:
http://www.politika.rs/vesti/najnovije-vesti/Pozar-u-buducem-izbeglickom-
centru-u-Nemackoj.lt.html, visited 5th October 2015.
[9] Tehnička preporuka za zaštitu od požara stambenih, poslovnih i javnih zgrada
(СРПС ТП 21/2002).

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[10] Glavni arhitektonsko – gradjevinski projekat –Pro–ING dd za projektovanje i

inženjering Novi sad.
[11] Elaborat zaštite od požara, objekat Sportsko – poslovni centar Beočin – Viša
tehnička škola, Institut za tehnologiju zaštite Novi Sad

[638]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 005.334:504
1
Jovana BONDŽIĆ
Nenad MEDIĆ2
Tanja NOVAKOVIĆ3
Ljiljana POPOVIĆ4
Đorđe ĆOSIĆ5

ASPECTS OF PETROL STATION ACCIDENT MODELING

Abstract: A high concentration of people and economy in urban areas brings an opportunity for global
prosperity while at the same time poses various risks to inhabitants, infrastructure and environment. A
cause of disaster risk in large cities could be even a routine people's activity such as filling up petrol. In
order to analyze risk of possible accidents at the petrol station, this paper provides a model of liquefied
petroleum gas (LPG) leaking accident at the petrol station in Novi Sad. Model was created by the use of
ALOHA software. For the purpose of designed case study overpressure from vapor cloud explosion and
toxic area of vapor cloud were modeled. Outputs from the model provided threat zones in which
inhabitants could be affected by the accident.

Кey words: Disaster Risk Management, Modeling, ALOHA, Liquefied Petroleum Gas

ASPEKTI MODELOVANJA AKCIDENTA NA BENZINSKOJ PUMPI

Rezime: Visoka koncentracija ljudi i privrede u urbanim sredinama donosi prilike za globalni prosperitet,
dok u isto vreme nosi rizike po anovni vo infra r k r i ivo n redin Uzro i rizika od ka a rofa
velikim gradovima mog i i ak i r in ke ak ivno i anovnika kao o je p njenje enzina na
enzin kim p mpama Kako i e analizirao rizik od mog eg ak iden a na enzinskoj pumpi, u radu je
o rađen model renja e nog naf nog ga a (TNG) iz ran por ne i erne na enzin koj ani i Novom
Sad Model je kreiran po re om ALOHA of vera Za po re e oda rane dija l aja analiziran je
uticaj eksplozije oblaka pare kao i ok i an i aj i paravanja TNG-a. Rezultati modela prikazuju zone u
kojima anovni i mog i i izlo eni i aj ak iden a.

Ključne reči: Upravljanje rizikom od ka a rofalnih događaja modelovanje ALOHA TNG.

1
Teaching Assistant, Faculty of Technical S ien e Trg Do i eja O radovi a 6 jovanasimic@uns.ac.rs
2
Tea hing A i an Fa l y of Te hni al S ien e Trg Do i eja O radovi a 6 medic.nenad@gmail.com
3
Tea hing A i an Fa l y of Te hni al S ien e Trg Do i eja O radovi a 6 tanja.novakovic.ns@gmail.com
4
Tea hing A i an Fa l y of Te hni al S ien e Trg Do i eja O radovi a 6 ljiljana.popovic.ns@gmail.com
5
Assistant Professor, Faculty of Technical Sciences Trg Dositeja Obradovica 6, djordje.cosoc@gmail.com

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1. INTRODUCTION
Disaster risk management is a field that is developing in past few decades, due to
increasing number of devastating catastrophic events. As it is stated in The Sendai
Framework for Disaster Risk Reduction 2015-2030: in the past decade over 700
thousand people have lost their lives, over 1.4 million have been injured and
approximately 23 million have been made homeless as a result of disasters [1]. These
facts are driving force for authorities, experts and stakeholders in the field, to initiate
actions regarding disaster risk reduction. Actions of research and scientific
communities dealing with disasters are constantly directed toward risk identification
and assessment.
From the scientific and engineering perspective disaster risk can be represented as
a temporal-spatial function of a series of complex parameters [2]:
R = f (H, V, E, CC, Re, etc.) (1)
Where:
R - is the Risk,
H - is the Hazard,
V - is the Vulnerability,
E - is the Exposure,
CC - is the Coping Capacity and
Re - is the Resilience [3].
In order to determine disaster risk, it is necessary to identify and assess all of these
parameters.
Hazard parameter determination includes hazard phenomena analysis. Hazards
that could be realized is necessary, but difficult (usually impossible), to be analyzed
in real systems before their occurrence. Therefore, creation of derived model of the
real system representing hazard phenomena is essential and initial step in the process
of disaster risk management.
In urban areas, high concentration of people and their routine activities could be
source of major accidents. Therefore, this paper analyses possible accident at the
petrol station in Novi Sad. For the purpose of analysis model of the liquefied
petroleum gas leaking from the tank trailer was created by use of ALOHA software.

2. POSSIBLE ACCIDENTS AT PETROL STATIONS

Activities at petrol stations could be potentially hazardous if they are not
adequately managed. Those activities could lead to:
 Exhaust gas emissions from vehicles moving through the petrol station
 Noise emissions from vehicles moving through the petrol station
 Deposition of exhaust gas products and oil products across working areas
 Solid waste generation
 Hydrocarbon emissions during refueling of storage tanks and tanks of vehicles

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Hydrocarbon emissions during refueling of storage tanks represent the greatest

risk at petrol stations, because of the consequences that could be caused. This is
particularly risky in case of LPG storage tanks refueling, mainly because relatively
small amounts of leaked LPG very quickly evaporate and can easily reach a
concentration at which ignition is possible.
LPG is composed of hydrocarbons that are in the gaseous state at ambient
temperature and atmospheric pressure. Relatively small increase in pressure (without
lowering temperature) turns it into liquefied state. Hydrocarbon liquids evaporate and
turn into vapor state with the drop of pressure. The basic components of LPG are
saturated hydrocarbons from which the LPG has the highest concentration of propane
and butane. The basic physico-chemical characteristics of LPG are presented in the
Table 1.
Таble 1- Basic characteristics of LPG (propane-butane) [4]
Characteristics Propane Butane
Chemical label C3H8 C4H10
Molar mass (kg/kmol) 44,09 58,12
The physical state at 20°C and 760 mmHg gas gas
Gas constant (J/kgºK) 188,8 143,2
Auto ignition temperature (°C) 500 429
Explosive limit 2.2-9.5 1.9-8.5

At petrol stations, underground tanks are used for storage of LPG. Loading of
underground tanks is performed through pump station and loading racks that are
located at an adequate distance. The delivery of LPG to petrol stations is performed
by tank trailers. Upon arrival, tank trailer is parked on handling area from where they
can fill up underground tanks for storage of LPG. This process could be hazardous in
terms of accident emergence in urban areas. One of the worst possible scenarios could
lead to leakage of LPG from the underground tank or tank trailer and explosion of
LPG vapor cloud.
Modeling this kind of accidents for purpose of risk assessment and analysis
requires acquiring necessary data about several parameters. Important parameters for
the petrol station accident modeling are:
 Location of the petrol station
 Meteorological conditions
 Tank parameters
 Tank rupture characteristics
 LPG characteristics and quantity
Model for the petrol station accident was created for the petrol station located in
Novi Sad. Locations of all petrol stations in Novi Sad available for LPG are presented
in the Table 2.

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Таble 2- Location of petrol stations available for LPG in Novi Sad
Name of the petrol station Address
OMV Novi Sad Partizanska bb, 21000 Novi Sad
OMV Novi Sad 2 Bulevar vojvode Stepe bb, 21000 Novi Sad
EKO – Bistrica 1 Bulevar vojvode Stepe 42, 21000 Novi Sad
EKO – Bistrica 2 Bulevar vojvode Stepe bb, 21000 Novi Sad
EKO - Novi Sad 3 P ajka kog odreda 21000 Novi Sad
Euro Gas Heroja Pinkija 2, 21000 Novi Sad
Euro Petrol Temerinski put 4, 21000 Novi Sad
Gazprom - Novi Sad 1 Maksima Gorkog 1, 21000 Novi Sad
Knez Petrol R mena ki p 61/C 21000 Novi Sad
Lukoil - Bistrica Bulevar vojvode Stepe bb, 21000 Novi Sad
Lukoil - Ki a ka Ki a ka 81 21000 Novi Sad
Lukoil - Novi Sad Venizelosova 32, 21000 Novi Sad
Lukoil - Temerinski put Temerinski put bb, 21000 Novi Sad
MOL - Novi Sad F o ki p 2 21000 Novi Sad
NIS Petrol - Novi Sad 4 F o ki p 93/D 21000 Novi Sad
NIS Petrol - Novi Sad 5 Sentandrejski put bb, 21000 Novi Sad
NIS Petrol - Novi Sad 7 R mena ki p 21000 Novi Sad
Radun AVIA P ajka kog odreda 1/C 21000 Novi Sad
Radun AVIA P ajka kog odreda 2/A 21000 Novi Sad
Radun AVIA B levar Ja e Tomi a 12 21000 Novi Sad

3. CASE STUDY – ACCIDENT MODELING

Petrol station Gazprom – Novi Sad 1, located at Maksima Gorkog 1 Street, in
Novi Sad was used for the purpose of the analysis in this paper. Designed case study
assumed that cause of accident was rupture at the tank trailer, and leaking of LPG
during storage tank refueling at the petrol station. Input parameters were modeled by
the use of ALOHA software.
3.1. Chemical releases modeling in ALOHA software
ALOHA (Areal Locations of Hazardous Atmospheres) is a computer program
designed to model chemical releases for emergency responders and planners [5]. Its
primary purpose is to provide emergency response personnel estimates of the spatial
extent of some common hazards associated with chemical spills. It deals specifically
with human health hazards associated with inhalation of toxic chemical vapors,
thermal radiation from chemical fires, and the effects of the pressure wave from
vapor-cloud explosions. [6]

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ALOHA was designed to provide an assessment of threat zones using information

that is commonly available to responders during an emergency. The user is required
to provide data on local atmospheric conditions, the identity of the chemical, and
details about the spill scenario. To minimize input data requirements, an extensive
database of chemical properties and geographical data are included in ALOHA. [6]
Threat zones represent the area within which the ground-level exposure exceeds
the user-specified level of concern at some time after the beginning of a release [6].
ALOHA will display up to three threat zones overlaid on a single picture. The red
threat zone represents the worst hazard. Threat zones can also be shown in Google
Earth or Google Maps u ing ALOHA’ KML expor fea re or in E ri’ Ar Map
using the ALOHA ArcMap Import Tool. [5] Outputs from modeling in ALOHA
software are displayed graphically and with a text summary.
3.2. LPG leakage accident
Input parameters for the accident modeling in ALOHA are divided into four
groups: site data, chemical data, atmospheric data and source strength data. For the
case study of LPG leaking accident site data included:
 Location: Maksima Gorkog 1, Novi Sad
 Time: November 4, 2015, 16.30h
For the chemical parameters, it was decided to choose propane as a prevalent
component of LPG mixture. Then, atmospheric data were as follows:
 Wind Speed and Direction: 1m/s, from east
 Cloud Cover: Clear
 Air Temperature: 9ºC
 Stability Class: F (Stable)
 Inversion Height: No inversion (assumed value)
 Humidity: 87%
The source strength is the rate at which the chemical enters the atmosphere or the
burn rate, depending on the scenario. In an ALOHA scenario, the source is the vessel
or pool from which a hazardous chemical is released. [7] In designed case study it
was assumed that LPG leaks from a tank trailer, then we modeled tank as a sorce
vessel. In order to model worst case scenario, all of source strength values were
asumed according to selection of the tank trailer with maximal available volume.
Input parameters and corresponding values for source strength were as follows:
 Tank Type and Orientation: Horizontal cylinder
 Volume: 50 m
3

 State of the chemical: Tank contains liquid

 Temperature within the tank: ambient temperature
 Mass in the tank: 20 tonnes
 Type of Tank Failure: Leaking tank, chemical is not burning as it escapes into
the atmosphere
 Area and Type of Leak: Circular opening, diameter 5 cm, through short
pipe/valve

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After entering input parameters we can model different hazrd scenarios for the
choosen type of tank failure. ALOHA's Display menu is where you can choose how
you want to see the results of ALOHA's calculations [8]. For the purpose of designed
case study Blast Area of Vapor Cloud Explosion and Toxic Area of Vapor Cloud
were modeled. Results are presented in the Figure 1 and Figure 2.

Figure 1 – Predicted area where the blast force from the explosion is hazardous

Figure 2 – Predicted area where the ground-level toxic vapor concentration may be
hazardous

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For the Blast Area of Vapor Cloud Explosion Hazard outputs from the model are
the red, orange, and yellow threat zones indicating the areas where the overpressure is
predicted to exceed the corresponding LOC (Level of Concern) at some time in the
hour after the release begins. Examples of effects to people and infrastructure that
could occur if that values are exceeded are written in the text accompanying the
default LOCs values at the diagram (Figure 1).
For the Toxic Area of Vapor Cloud Hazard outputs from the model are the red,
orange, and yellow threat zones indicate the areas where the ground-level pollutant
concentration is predicted to exceed the corresponding LOC at some time in the hour
after the release begins. Acute Exposure Guideline Levels (AEGLs) were selected as
toxic LOCs for this scenario.

4. CONCLUSION
Output from the model of LPG leaking accident, representing threat zones i.e.
zones in which people and infrastructure could be exposed to the hazard, is important
result in the process of disaster risk identification in urban areas. This case study
showed that dealing with hazard phenomena by the use of model significantly eases
identification of hazard dispersion. Furthermore, resulted information from the model,
as an input data, could be brought in the spatial context jointly with data about
vulnerability and resilience hot spots within analysed environment. Based on such
spatial model, it is possible to create spatial information system for disaster risk
management for the area of Novi Sad which is in accordance with global disaster
reduction policy.

REFERENCES
[1] Sendai Framework for Disaster Risk Reduction 2015 – 2030, adopted on Third
United Nations World Conference on Disaster Risk Reduction, 14-18 March
2015, Sendai, Miyagi, Japan
[2] Turner, B.L. et al., 2003, A Framework for Vulnerability Analysis in
Sustainability Science, Proceedings, National Academy of Sciences 100 (14),
pp.8074-8079
[3] Ćo i Đ Popov S Sak l ki D Pavlovi A 2011 Geo-Information
Technology for Disaster Risk Assessment, Acta Geotechnica Slovenica, pp. 65-
74.
[4] Niki ovi S Modeling of accident effects at the petrol stations by use of GIS,
Bechelor thesis, 2013, Faculty of Technical Sciences, Novi Sad
[5] ALOHA fa hee NOAA’ Na ional O ean Servi e Offi e of Re pon e and
Restoration, Available at:
http://response.restoration.noaa.gov/sites/default/files/aloha.pdf, visited on 6th
November 2015

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[6] ALOHA (Areal Locations of Hazardous Atmospheres) 5.4.4, Technical

Documentation, 2013, National Oceanic and Atmospheric Administration
(NOAA), Office of Response and Restoration, Available at:
http://response.restoration.noaa.gov/sites/default/files/ALOHA_Tech_Doc.pdf,
visited on 6th November 2015
[7] ALOHA Help, Available at:
file:///C:/Program%20Files/ALOHA/AlohaHelp/aloha_help.htm#source/tanksou
rce/tank_size_and_orientation.htm, visited on 6th November 2015
[8] ALOHA Help, Available at:
file:///C:/Program%20Files/ALOHA/AlohaHelp/aloha_help.htm#results/threatzo
ne/hazard_to_analyze.htm, visited on 6th November 2015

[646]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 005.334:504
1
Suzana VUKOSLAVĈEVIĆ
Mirjana LABAN2
SrĊan POPOV3
Slobodan ŠUPIĆ4

CRITICAL ANALYSIS OF THE EVACUATION SIMULATION

SOFTWARE'S APPLICATION
Abstract: Investigation of issues related to evacuation of people from fire endangered area requires an
analysis of a large number of available tools, in order to predict the evacuation flaw that would be similar
to real conditions as much as possible. The critical analysis of capabilities of evacuation simulation
software (Pathfinder), applied in the case study for the Amphitheaters building at the Faculty of
Technical Sciences in Novi Sad, was carried out. Obtained results show that selection of different
simulation modes may cause different output of software package. Identification and detailed analysis of
the environmental performances contribute to improvement of results’ quality aiming more realistic
perception of evacuation process in terms of real fire event.

Кey words: fire safety, evacuation, modeling, simulation, Pathfinder.

KRITIČKA ANALIZA PRIMENE SOFTVERSKOG PROGRAMA ZA

SIMULACIJU EVAKUACIJE
Rezime: Prouĉavanje problematike evakuacije ljudi iz požarom ugroženog prostora zahteva analizu
velikog broja dostupnih alata kako bi se predvideo tok evakuacije koji bi u što većoj meri odgovarao
realnosti. U radu je sprovedena kritiĉka analiza mogućnosti softverskog paketa za simulaciju evakuacije
(Pathfinder) primenjenom u studiji sluĉaja evakuacije Bloka Amfiteatara Fakulteta tehniĉkih nauka u
Novom Sadu. Rezultati istraživanja ukazuju da se na osnovu odabira razliĉitih režima kretanja ljudi
tokom evakuacije može doći do razliĉitih izlaznih rezultata softverskog paketa. Identifikacija i detaljna
analiza performansi okruženja doprinose unapreĊenju kvaliteta rezultata u cilju realnijeg sagledavanja
procesa evakuacije u uslovima realnog dogaĊaja požara.

Ključne reči: požarna bezbednost, evakuacija, modelovanje, simulacija, Pathfinder.

1
MSc, Teaching Assistant, University of Novi Sad, Faculty of Technical Sciences, Serbia, suzanav@uns.ac.rs
2
PhD, Assistant Professor, University of Novi Sad, Faculty of Technical Sciences, Serbia, mlaban@uns.ac.rs
3
PhD, Assistant Professor, University of Novi Sad, Faculty of Technical Sciences, Serbia, srdjanpopov@uns.ac.rs
4
MSc, Teaching Assistant, University of Novi Sad, Faculty of Technical Sciences, Serbia, ssupic@uns.ac.rs

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1. INTRODUCTION
During their lifetime, humans spend most of their time in public buildings:
starting from maternity wards in which they are brought to the world, through
kindergartens, schools, universities, work places, hotels, nursing homes, etc. That
time they spend with at least hundreds of other people. It is well known that where
there is a man - there is a risk, so in case of fire incident in these buildings, evacuation
of hundreds of people is required. Under such circumstances, the occupants have to
be evacuated from the fire endangered area as fast as possible. In order to make it
possible, understanding of large crowds' dynamics during evacuation is very
important.
Evacuation processes can be predicted by using one of the following approaches:
conducting the experimental evacuation exercise, using hand calculations and using
the evacuation simulation models. For evacuation analysis, hand calculations can
sometimes be very exhausting and imprecise and do not provide information on
critical points, while performing of evacuation exercises cost too much and can be
time consuming, and also dangerous. Therefore, in recent years, within assessment of
buildings' fire risk, evacuation models are becoming the main tool. However,
nowadays, there is a large number of evacuation simulation tools in the market, so
choosing an appropriate simulation tool for solving problems requires perceiving of
all their possibilities and limitations. Fortunately, in many publications [1, 2, 3, 4, 5]
we can find guidance on how to perform egress assessment, along with analyzes of
possibilities and limitations of different types of evacuation simulation tools [6,7].
This paper presents the use of different simulation modes provided by Pathfinder
simulation evacuation software and the ways it can affect the results of simulation.
Also, some of challenges when simulating movement in building evacuation model
are described within paper, as well as limitations and the accuracy of the software
referring to real evacuation scenarios. The critical analysis of capabilities of the
software was carried out through case study for the Amphitheaters building at the
Faculty of Technical Sciences in Novi Sad.

2. EVACUATION SIMULATION SOFTWARE

There is a number of evacuation simulation softwares on the market, each with
unique characteristics and specialties, according to [6].
These simulation softwares differ in following features: availability to the public,
modeling method, purpose of the model, evacuation flow, perspective of the
model/occupant, occupants’ representation, occupants’ behavior, occupants’
movement, possibility of incorporating fire data, types of output, verification and
validation method, etc.
Building simulation model chosen for this study is Pathfinder. Pathfinder is non-
behavioral egress modeling tool that, as modeling method, uses only the occupants'
movement from one point in the building to another one, such as the movement from

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the evacuation area to the exit or safe place. It does not consider the human behavior
aspect of the occupants. It has possibility of simulating of any type of building and as
an infinite network model it provides continuous movement of persons throughout the
model (floors are divided into number of small grid cells and the movement of the
occupants is performed from one cell to another one). Occupants’ speed and flow in
the model is based on the density of the space. Simulations are performed in non-fire
mode but it is possible to import smokeview slice files from another model to show
various properties of a fire simulation, including smoke viscosity, temperature, and
visibility [8]. It also provides textual and visual (2D, 3D) representation of outputs.

3. OCCUPANTS' MOVEMENT IN PATFINDER'S MODELS

Pathfinder can model occupants using three different simulation modes,
determining occupants movement:
A. Pathfinder's default simulation mode:
 “Steering Mode”- it is an agent-based model, refined in [9], in which each
occupant uses the steering system to avoid obstacles and other occupants
on their evacuation path. In this mode, doors do not represent the limiting
factor to the occupants flow;
B. Pathfinder's alternative simualtion modes:
 “SFPE Mode” - it uses the hydraulic flow method described in the Society
of Fire Protection Engineering Handbook [2], in which occupants do not
avoid each other, instead they are allowed to overlap in space during
evacuation. In fact, in this mode, walking speed is based on the density of
the space and the capacity of doors and stairways, as flow through egress
components is the limiting factor;
 “Steering + SFPE Mode” – it is a combination of two above mentioned
modes (it is basically Steering mode with enabled limit door flow rate).
When modeling in Pathfinder, user has the ability to assign different profiles to
actors. These profiles may differ in walking speeds, exit selection, goals, delay time
and other.
Within the model, the walking speed depends on the size of the evacuating crowd.
According to [10], as long as the density is less than 0.55 pers/m2, an occupant will
perform his movement under the maximum speed, while occupant’s velocity
decreases to zero when it reaches a maximum density of 3.8 pers/m2. For most
evacuation simulation models, agents usually have assigned a specific unimpeded
speed by the user or modeling program. However, in high density situations, when we
have queuing and congestion od people within the building, walking speed halts.
During evacaution, escape route selection of the occupants is based on the
shortest distance or shortest cue, unless it is defined differently.

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4. EXPERIMENTAL INVESTIGATION
In order to verify how selection of different simulation modes, provided by
evacuation simulation software (Pathfinder), may influence the simulation results, the
case study for the Amphitheatres building at the Faculty of Technical Sciences in
Novi Sad was carried out. All three simulation methods were analyzed and
comparison of results was performed.
The Amphitheaters building is a one-storey building situated on the campus of the
University of Novi Sad, in Serbia. It consists of two large (Figure 1) and two smaller
lecture theatres with evacuation routes to final exits or safe place at the basement
level, ground level and at the first floor level.

Figure 1 – One of four Faculty’s amphitheaters

Based on relevant basic data on the building and their occupants, model was
created (Figure 2) and simulations performed.

Figure 2 – Pathfinder’s building evacuation simulation model

In all three simulation modes, all simulator options were left at the default settings,
except occupants' maximum walking speed.
Each actor has assigned maximum walking speed (1.5 m/s), where walking speed
represents unimpeded walking speed, according to Serbian technical
recommendations SRPS TP 21 [11]. Occupants’ walking speed decreases when area
becomes crowded with other occupants or if they are moving downstairs.
The total number of people modeled in the simulation is about 830, determined on
the basis of amphitheaters’ seating capacity.
The scenario foresee evacuation where occupants from all amphitheatres are
starting to move at the same time. The occupants have been assumed to choose the

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shortest path to the nearest final exit. This is realistic in case that occupants are
familiar with the building layout and its egress design.

5. RESULTS DISCUSSION
Total times required to evacuate all occupants from amphitheatres, obtained by the
computer model and based on chosen simulation mode, are following:
 Simulation in Steering Mode: 6min 5s
 Simulation in SFPE Mode: 9min
 Simulation in Steering + SFPE Mode: 8 min 4s
Simulation of evacuation in steering mode resulted with visually more realistic
movement (Figure 3), regarding to simulation results obtained under SFPE mode
(Figure 4). Considering the total evacuation time needed for evacuation of all persons
present in the building, steering mode resulted with the fastest escape time. The
reason for that might be a fact that doors are not the limiting factor to the occupants
flow in this mode. If we set doors to be a limiting factor, what is the case in Steering
+ SFPE mode, it is possible to obtain the most realistic results, regarding other two
modes (Figure 5).

Figure 3 – Occupants’ movement in steering mode: movement of occupants looks realistic

Figure 4 – Simulation of evacuation under SFPE mode: does not look very realistic

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Figure 5 – Simulation of evacuation under Steering + SFPE mode: most realistic behaviour of
occupants
Problem may also represent occupants’ goal to choose the shortest route while
trying to escape. It raises a question how really occupant are familiar with the
building. We have to notice that, besides lectures that being hold in the amphitheaters,
they are also intended for conferences and gala reception of freshmans, who for the
first time enters the building.
In both steering modes the occupants will retain a separation distance when
evacuating, while the SFPE mode allows occupants to overlap (Figure 6), what does
not meet the reality and also make tracking the movement of individuals difficult.

Figure 6 – In SFPE mode occupants are allowed to be located at the same spot

The SFPE mode allows occupants to instantly reach their maximum speed and to
transit between different speeds without accounting for acceleration, that is not the
case under real conditions. In Steering mode, inertia is taken into account.
Inertia also impacts the effective flow rates through the doors for the
Steering+SFPE mode, since each occupant must accelerate when released to pass
through the door [12].
In Figure 7, observing of movement paths shows that all occupants are
successfully passing the corners. Also, in Steering mode occupants use a quadratic B-

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spline to perform their movement from current point to desired one, while in SFPE
mode, this curve is merely a straight line [10].
(a) (b) (c)

Figure 7 – Traces of occupants’ paths and their movement near corners: (a) Steering mode,
(b) SFPE mode, (c) Steering + SFPE mode

6. CONCLUSION
In most fire incidents a successful evacuation and rescue can mean the difference
between life and death [13].
In fire safety engineering, the performance based design concept relies strongly on
the use of computer simulations of fire and evacuation processes [9]. Today,
simulation of evacuation represent an efficient method of finding the best escape
concepts that would increase safety of the people present in the building when fire
breaks out.
The critical analysis of capabilities of evacuation simulation software (Pathfinder),
applied in the case study for the Amphitheaters building at the Faculty of Technical
Sciences in Novi Sad, was carried out. The reason of choosing Pathfinder building
model is its possibility to be coupled with an external fire model to form a portion of
hazard analysis, which is definitely a next step to take in further research. Also,
despite the fact that only the movement aspect of the evacuation is simulated,
Pathfinder’s models are practical as they indicate the critical points within the
simulated building, such as congestion areas, queuing of people and/or bottlenecks,
what can significantly increase the reliability when predicting these processes.
Evacuating the large number of people under fire condition is surely a challenge.
Obtained results show that selection of different simulation modes may cause
different output of software package. Therefore, identification and detailed analysis of
the environmental performances contribute to improvement of results’ quality aiming
more realistic perception of evacuation process in terms of real fire event and
increasing the reliability of simulations.

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ACKNOWLEDGEMENTS
The paper presents the part of research realized within the project “Development
and Application of Contemporary Procedures for Design, Construction and
Maintenance of Buildings” conducted by the Department of Civil Engineering and
Geodesy, Faculty of Technical Sciences, University of Novi Sad.

REFERENCES
[1] SFPE Engineering Guide - Human Behavior in Fire, Bethesda, MD: Society of
Fire Protection Engineers, 2003.
[2] Gwynne, S.M. and E.R. Rosenbaum, Employing the Hydraulic Model in
Assessing Emergency Movement, The SFPE Handbook of Fire Protection
Engineering. Bethesda, MD: National Fire Protection Association: Bethesda,
2008.
[3] Ogunlana, K. and Sharma, S. 2014. Agent based simulation model for data
visualization during evacuation, proceedings of 2014 ASE/IEEE
BIGDATA/SOCIALCOM/CYBERSECURITY Conference, pp.1 -6
[4] Shi, J., Ren, A. And Chen, C. 2009. Agent-based evacuation model of large
public buildings under fire conditions, Automation in Construction 18, 338–347
[5] Shen, T.S. 2003. Building Planning Evaluations for Emergency Evacuation,
Ph.D. Thesis, Worcester Polytechnic Institute, Worcester, MA, USA.
[6] Kuligowski, E.D., Peacock, R.D. and Hoskins, B.L. 2010. A Review of Building
Evacuation Models, 2010, U.S. Department of Commerce, National Institute of
Standards and Technology.
[7] Lord, J., Meacham, B., Moore, A., Fahy, R., Proulx, G. 2005. Guide for
evaluating the predictive capabilities of computer egress models, NIST Report
GCR 06-886.
[8] https://www.thunderheadeng.com/pathfinder/pathfinder-features/
[9] Amor, H.B., Murray, J. and Obst, O. 2006, Fast, Neat, and Under Control:
Arbitrating Between Steering Behaviors, AI Game Programming Wisdom 3, ed.
S. Rabin. pp. 221-232.
[10] Thunderhead Engineering, Pathfinder Technical Reference, 2013. Thunderhead
Engineering Consultants, Inc., Manhattan.
[11] SRPS TP 21: Technical recommendation for structural fire protection for
residental, business and public buildings, 2003.
[12] Thunderhead Engineering, Pathfinder Verification and Validation, 2015.
Thunderhead Engineering Consultants, Inc., Manhattan.
[13] Cuesta, A., Alvear, D., Abreu, O. and Silio, D. 2014. Real-time Stochastic
Evacuation Models for Decision Support in Actual Emergencies, 11th
International Symposium on Fire Safety – IAFSS, Nueva Zeland.

[654]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 005.334:504
1
Mladen MILANOVIC
Milan GOCIC2
Slavisa TRAJKOVIC3

SURVEY OF RECOMMENDATIONS FOR DROUGHT

MANAGEMENT
Abstract: Natural hazards have major consequences on the life and work of people and at the
environment. Hydrological hazards (drought, floods and landslides), as a group of natural hazards caused
by rainfall, have more pronounced in recent years. In order to reduce influence and consequences of
hydrological hazards, it is important to monitor and develop the studies of hazards.
Drought is one of the most recognizable hydrological hazards and requires special attention. Thus, the
recommendations are presented for drought management..

Кey words: Hydrological hazards, drought, drought management.

PREGLED MERA ZA UPRAVLJANJE SUŠOM

Rezime: Prirodni hazardi imaju velike posledice na život i rad ljudi i na životnu sredinu. Hidrološki
hazardi (suše, poplave i klizišta), kao grupa prirodnih hazarda izazvana od strane padavina, su sve više
izraženi poslednjih godina. Kako bi se smanjio uticaj i posledice hidrološkh hazarda, važno je da se one
prate a takođe i da se razvijaju studije o njima.
Suša predstavlja jedan od najprepoznatljivijih hidroloških hazarda pa samim tim i zahteva posebnu
pažnju. Iz tog razloga predstavljene su preporuke za upravljanje sušom.

Ključne reči: Hidrloški hazardi, suša, upravljanje sušom.

1)
Dr, independent scientist-researcher, http://matrix-structures.com, mladen.cosic@ymail.com
2)
Mr, University of Belgrade, Faculty of Mechanical Engineering, Innovative center, boris.folic@gmail.com
3)
Prof. emeritus Dr, University of Novi Sad, Faculty of Technical Sciences, folic@uns.ac.rs
4)
Dr, Institute for testing materials - IMS, Belgrade, nenad.susic@institutims.rs

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1. INTRODUCTION
Drought is one of the most complex natural hazards that threatened the largest
number of people and limited agricultural production [1]. It causes the great damages
in different sectors of economy. Thus, it is necessary to conduct the analysis of
drought and to take the measures against it.
Many scientists and organizations have developed and analyzed the plans for
drought management in order to mitigate the drought impacts [1-7]. In [8], three basic
components in drought planning were presented i.e. monitoring and early warning,
risk assessment and mitigation and response. A new climate monitoring product
(drought monitor) was also presented for the territory of United States to illustrate
how climatic parameters and indices can be used to produce a weekly comprehensive
assessment of drought conditions and severity levels. In [9], water resources
management was analyzed for the Mediterranean as well as the plans for drought
mitigation. Droughts were reconstructed in Anglian region (UK) for the period 1798-
2010 in [10] to assess the consequences for water resources planning, drought
management and resilience. The simulation of five reservoir in water resources
management and drought plans was used. In [11], the analysis of costs and benefites
of preventive measures for drought mitigation in Serbia was done.
This study analyzes the drought consequences in the world and consequences of
drought to the agricultural production in Serbia. The analysis was conducted in order
to better understand the size of drought impact. The recommendations for drought
management based on development of drought management plan were presented.

2. DROUGHT CONSEQUENCES
In time perception, drought impacts should be considered first as an assessment of
historical events and second as an assessment of future events. Consequences caused
by drought are in all parts of nature. To easier study and analysis of drought
consequences, National Drought Mitigation Center (http://drought.unl.edu) classified
them in three groups: 1) economic, 2) environmental and 3) social consequences.
The agricultural production represents the sector of economy that suffers the
largest impacts of drought, because the plants are the best indicator of drought [5].
Economic consequences of drought also affect the related sectors with agriculture,
such as forestry and fisheries. Damages in forestry are the great because the number
of wildfires, the insect infestations, plant diseases and wind erosion grow. Drought
causes the discharge of river that leads the river navigation decreases and the
transportation costs increases. Also, tourism industries are affected and these leads to
reduced business and unemployment. Hydropower production is affected and the
consequence is the production of electricity on expensive way. During the drought
season the water supply can easily be threatened.
Big problem with environmental impacts of drought are that they are difficult to
quantify. Environmental consequences are primarily to harm to the environment such

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as damages of plants and animals, air and water quality, forest, loss of biodiversity
and soil erosion. There are two types of these consequences: 1) short-term where after
drought conditions return to normal and 2) where consequences linger some time or
become permanent.
Social consequences are related to the endangerment of life in environment. Large
number of drought consequences (economic and environmental) have social
components. Some of social impacts reduce quality of life, public safety and health
and conflicts between water users.
According to United Nations International Strategy for Disaster Reduction
Secretariat (UNISDR), drought causes great consequences in human population,
environment and economy, for the period 1975 – 2008 [2]. For analysis of drought
consequences in the world, data were taken from EM–DAT (www.emdat.be). Table 1
shows the consequences of drought to people and their property on decades in the
world, during the period 1900 – 2015. Table 1 shows that most of the droughts in the
period from 1900 to 2015 were during the 2001-2015. The number of droughts was
1148 in the world. Data showed that number of droughts grows from decade to
decade. For the same period number of injured and total damages were 49.888 and
187.392.048, respectively, and are the greatest during the all observed period.
Number of total deaths is the greatest during the period 1931–1940 (5.003.509
people), and after 1951 year the number of total deaths grows together with the
growth of drought occurrence. Data of total affected people were the greatest from
1921 to 1930 and the maximum number of people who became homeless was
1.438.650 for the period of 1961–1970.

Table 1 – Consequences of drought in the world (1900 – 2015)

Total
Total Total
Year Occurrence affected Injured Homeless
deaths damage ($)
(people)
1900-1920 48 2.630.093 152.233 938 0 196.000
1921-1930 39 1.205.101 18.016.823 1.823 0 106.500
1931-1940 53 5.003.509 2.622 2.622 0 10.000
1941-1950 48 125.290 15.632 1.525 14.000 31.000
1951-1960 50 7.783 893.227 3.016 182.966 745.000
1961-1970 77 7.867 3.745.099 21.964 1.438.650 5.349.200
1971-1980 163 14.507 3.325.483 26.655 527.200 31.805.600
1981-1990 463 38.056 12.443.728 43.460 639.450 87.376.200
1991-2000 703 15.215 13.886.265 20.966 583.770 94.585.079
2001-2015 1148 150.225 12.759.918 49.888 191.232 187.392.048

Countries with the biggest number of total affected people of drought in the world,
are India and China for the observed period (1900-2012), table 2. In India, the
greatest number of total affected people was in July 2002 and May 1987 with

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300.000.000 people, while 82.000.000 people were affected in China in January 1994
and that is the greatest number of affected people for China.

Table 2 – Number of total affected people at a country level for the period 1900-2012
Total affected
Country Date
(people)
India July 2002 300.000.000
India May 1987 300.000.000
India 1972 200.000.000
India 1965 100.000.000
India Jun 1982 100.000.000
China Jan 1994 82.000.000
China Oct 2009 60.000.000
China Apr 2000 60.000.000
India Apr 2000 50.000.000
China Jun 1988 49.000.000

Figure 1 shows the greatest ten economic drought consequences and their costs at
a country and monthly level, for the period 1900 – 2012. From all countries, United
States have the greatest economic consequences caused by drought and that was in
June 2002. The total damage was estimated on 20.000.000 $. United States have three
times the greatest economic consequences from drought in top ten countries. After
United States, the greatest damage had China (13.755.200 $) in January 1987. The
last country in top ten countries with the greatest total damages was Canada with the
damage of 3.000.000 $ in January 1977.

Figure 1 – Top ten economic damage from drought at a country level for
the period 1900-2012

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Drought consequences for all continents for the period 1900-2015 are shown in
table 3. The greatest number of drought events was recorded in Africa (297), while
the minimum number was in Oceania (22). The number of total deaths and total
affected people, 9.663.389 and 1.744.562.029, respectively, were the greatest for
Asia. Second continent after Asia by the number of total deaths was Europe with the
value of 1.200.000, and Africa was after Asia by the number of total affected people
(371.035.501). The total damage was the greatest for both Americas together and that
was 57.771.139.000 $, and the minimal was for Africa with the value of
2.984.593.000 $.

Table 3 – Drought consequences on the territory of each continent for the period 1900-2015
Events count Total affected Total damage
Continent Total deaths
(year) (people) (x103 $)
Africa 297 867.143 371.035.501 2.984.593
Americas 142 77 104.090.026 57.771.139
Asia 159 9.663.389 1.744.562.029 37.956.865
Europe 42 1.200.000 15.488.769 25.481.309
Oceania 22 660 8.034.019 11.526.000

Figure 2 shows the production of wheat and maize on the territory of Serbia for the
period 1970-2014. Production during the years with catastrophic droughts is
significantly reduced especially in 2000 and 2003.

Figure 2 – Production of wheat and maize

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3. RECOMMENDATIONS FOR DROUGHT MANAGEMENT

There are great changes between regions, and how drought represents the regional
phenomenon that is in relationship with time, then each drought represents the unique
phenomena with its characteristics and influence on wildlife and environment. In
order to prevent these impacts, every country should develop national plans and
measures for drought mitigation.
Successful drought management is only possible if the approach to the risk of
drought is based on comprehensive and systematic way. In analysis of drought and
measures against it the first step is quality database that defines characteristics of
drought conditions and a quantification of drought intensity.

Figure 3 - Elements of drought management plan

According the Global Water Partnership Central and Eastern Europe [3], there are
seven elements in drought management plan, figure 3. From all elements of plan, three
elements stand out as the most important [4]:
 drought indicators and thresholds for drought classification and the drought early
warning system,
 programm of measures to achieve specific objectives in each drought stage and
 the organizational framework to manage drought.
Drought indicators represent important tools for drought quantification. For that
reason, it is necessary to define indices of drought which will be used as standard
monitoring tools in declaration of drought. The basic component in drought planning
is mitigation measures. According to the nature of drought, the measures that are used
in drought management can be classified as strategic, tactical and emergency [12].
Strategic measures represent structural and institutionalized measures that are long-
term and they are oriented to the reducing vulnerability of water supply systems.
Tactical should give response to the expected water shortage. This group of measures

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have been usually developed earlier. Emergency measures are in use when drought
conditions have specific form.
In [6], the group of measures against drought can be classified in three sub-
categories:
 water-supply oriented measures,
 water-demand oriented measures and
 drought impact minimization measures.
The organizational framework should contain key information about
organizational structure needed for the production, implementation and update of the
drought management [3]. One of the possible organizational frameworks represents the
cluster organization against drought. This cluster includes the representatives of
government, firms and academic institutions. Detailed organization structure of such
association in cluster for drought mitigation on the territory of Serbia was presented in
[13].

4. CONCLUSION
The paper gives an overview of drought consequences in the world and in Serbia.
These consequences impose the need for integrated approach against drought. Also,
drought management plan was presented in order to achieve the following aims:
 building climate resilience,
 reducing economic and social losses and
 responding to specific regional and national needs and requirements.
The future study will be oriented in defining the list of priorities in water supply of
urban and rural parts of the country during the drought.

ACKNOWLEDGEMENT
The research presented in the paper is funded by the Ministry of Education,
Science and Technological Development, Republic of Serbia (Grant No. TR 37003).

REFERENCES
[1] Wilhite, D. A., Svoboda, M. D., Hayes, M. J. (2007): Understanding the complex
impacts of drought: A key to enhancing drought mitigation and preparedness,
Water Resour Manage, 21, 763-774.
[2] United Nations International Strategy for Disaster Reduction Secretariat
(UNISDR), Geneva, Switzerland, 2009.
[3] Global Water Partnership Central and Eastern Europe (2015): Guidelines for
preparation of the Drought Management Plans, Develpoment and
implementation in the context of the EU Water Framework Directive.

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[4] European Commission (2007): Drought Management Plan Report, Including

Agricultural, Drought Indicators and Climate Change Aspects, Water Scarcity
and Droughts Expert Network, Technical report 2008-023, Luxembourg.
[5] Rakićević, T. (1988): Regionalni raspored suše u SR Srbiji, Glasnik srpskog
geografskog društva, 1, 9-18.
[6] Yevjevich, V., Cunha, V.L., Valchos, E. (1983): Coping with drought. Littleton,
Colorado, Water resources publications.
[7] Mishra, A.K., Singh, V.P. (2011): Drought modeling – A review, Journal of
Hydrology, 403, 157-175.
[8] Wilhite, D.A., Svoboda, M.D. (2000): Drought Early Warning Systems in the
Context of Drought Preparedness and Mitigation, Proceedings of an Expert
Group Meeting, World Meteorological Organization (WMO/TD No. 1037),
September 5-7, 2000, Lisbon, Portugal, 1-21.
[9] Hamdy, A., Trisorio-Liuzzi, G. (2008): Drought planning and drought mitigation
mesures in the Mediterranean region, Options Méditerranéennes, Series A, 80,
235-239.
[10] Spraggs, G., Peaver, L., Jones, P., Ede, P. (2015): Re-construction of historic
drought in the Anglian Region (UK) over the period 1798-2010 and the
implications for water resources and drought management, Journal of
Hydrology, 526, 231-252.
[11] Milanovic, M., Gocić, M., Trajković, S. (2014): Analiza koštanja i benefita
preventivnih mera za ublažavanje suša, Zbornik radova Građevinsko-
arhitektonskog fakulteta, 29, 145-156.
[12] Water scarcity drafting group (2006): Water scarcity management in the context
of WFD.
[13] Milanović, M., Trajković, S., Gocić, M. (2012): Klastersko povezivanje
institucija u cilju ublažavanja efekta suše, Nauka+Praksa, 15, 77-82.

[662]
EUROPEAN STANDARDS IN THE DESIGN
AND CONSTRUCTION OF STRUCTURES
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
Delyana BOYADZHIEVA

DESIGN OF TIMBER ELEMENTS SUBJECT TO COMPRESSION

COMPARISON BETWEEN EUROCODE 5 AND BUILDING
REGULATIONS OF RUSSIA AND JAPAN
Abstract: The purpose of this paper is to compare the main provisions of the building regulations in
Europe, Russia and Japan which concern the design of timber elements subject to compression. First of
all we discuss the effective area of cross-section of elements with holes or notches. Then we discuss the
effective length of the elements and the main buckling modes with the corresponding values of the
instability factor. After that a comment on the determining of the value of the instability factor according
to the building regulations is presented. The results of this comparison can be used to improve the
building regulations of the countries concerning the design of timber elements.

Кey words: timber, compression, design, building regulations

PROJEKTOVANJE DRVENIH ELEMENATA IZLOŽENIH PRITISKU

- POREĐENJE EUROCODE-A 5 I GRAĐEVINSKIH PROPISA U
RUSIJI I JAPANU
Rezime: Cilj ovog rada je poređenje glavnih odredbi propisa o izgradnji u Evropi, Rusiji i Japanu koji se
tiču projektovanja drvenih elemenata izloženih pritisku. Pre svega, diskutovaće se o efektivnoj površini
poprečnog preseka elemenata sa rupama ili zarezima. Dalje će se diskutovati o efektivnoj dužini
elemenata i osnovnim režimima izvijanja sa odgovarajućim vrednostima faktora nestabilnosti. Nakon
toga, dat je komentar na utvrđivanje vrednosti faktora nestabilnosti u skladu sa građevinskim propisima.
Rezultati ovog poređenja mogu se koristiti za poboljšanje građevinskih propisa zemalja koje se bave
projektovanjem elemenata drveta.

Ključne reči: drvo, pritisak, projektovanje, građevinski propisi

Dr. Eng., Faculty of Structural Engineering, University of Architecture, Civil engineering and geodesy - Sofia,
1 Hristo Smirnenski Blvd., Sofia 1046, Bulgaria, E-mail :delianab@yahoo.com

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1. INTRODUCTION
Eurocodes are sets of harmonized technical rules developed by the European
Committee for Standardisation for the structural design of construction works in the
European Union. By March 2010 the Eurocodes are mandatory for the specification
of European public works.
In Japan there are the Building Standard Law and the Enforcement Ordinance of
Building Standard Law, which are mandatory for design of buildings. The actual
design methodology that is shown in the “Standard for Structural Design of Timber
Structures - Allowable Strength Design Method” by the Architectural Institute of
Japan is not mandatory. The Building standard law of Japan is issued by the Central
Government – The Ministry of Land, Infrastructure, Transport and Tourism [1, 2, 6].
The Building regulation framework of Russia is issued by the Ministry of
Regional Development of the Russian Federation. These regulations are mandatory,
named SNIP that means Building Code [9].

2. DESIGN METHODS
Structural engineering theory is based upon applied laws of physics and empirical
knowledge of the structural performance of different materials and geometries.
The Russian and the European Union’s (Eurocode Standard) building codes
provide design methodology based on the Limit States Design.
The Building regulation of Japan for Timber structures is based on 5 methods,
depending on the floor area and height of the building. The methods are: Wall amount
(quantity) method, Allowable stress method, Horizontal load carrying capacity
method - Limit state design, Capacity spectrum method – CSM (Response and limit
strength calculation method) and Time history response analysis.

3. ABOUT THE ELEMENTS SUBJECT TO COMPRESSION

In the beginning it is important to take notice of the difference between the
Building regulations concerning the design of elements subject to compression.
According to Eurocode 5 [5] there are two main groups of elements – beams and
columns. The design procedure depends of the type of the element. The beams are
these elements that are subject to bending or combination of axial compression and
bending about the strong axes of the cross-section. These elements have a risk of
lateral torsional buckling. The columns are these elements that are subject to
compression or a combination of compression and bending. These elements have a
risk of loss of stability (buckling).
According to the Building Code of Russia [9] the case of elements subject to
combination of axial compression and bending is one, but the design procedure
depends of the ratio between the compression and the bending stresses. In this case
the elements are subject to bending about the strong axes of the cross-section, and the

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failure may happen due to lateral buckling out of the plane of the bending moment. If
the ratio between bending and compression stresses is less than 0,1 the element have
to satisfy the design procedure for element subject to axial compression only.
Standard for Structural Design of Timber Structures of Japan [1] presents one case
– element subject to combination of axial compression and bending.

4. LOAD BEARING CAPACITY

Determining of the load bearing capacity ( Fc ) of the elements subject to
compression in general is:
Fc  Factor . Effective area .Compresion strength (1)
The “Factor” is the one that takes into account the slenderness of the element. This
factor is commonly called Instability factor. According to the different Building
regulations the instability factor is marked as  (Standard for Structural Design of
Timber Structures of Japan) [1],  (Russian Building Standard Code) [9] or
kc , y and kc , z (Eurocode 5) [5]. These factors depend on the value of the slenderness
of the element  .
The effective area of the cross-section takes into account the holes and the notches
of the element.
The compression strength of the element depends on the timber strength class.

5. EFFECTIVE AREA OF CROSS-SECTION

5.1. Eurocode 5
According to Eurocode 5, the area for determining the compression stresses of the
element is the effective cross-section. All holes within a distance of half the minimum
fastener spacing measured parallel to the grain from a given cross-section should be
considered as occurring at that considered cross-section (Fig. 1).
5.2. Building Code of Russia
The effective area of the cross-section for elements subject to compression
depends on the position and area of the notch (hole), if there are any. The cross-
section with notch or hole has to be symmetric, with the same axes as the sections
without notch.
The effective area for element without holes or notches, and if there are notches in
the cross-section that does not reach the edge of the element, and if they are less than
1/4 of the area of the section (Fig. 2 – case A), is:
Aeff  A (2)

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Figure 1 – Effective area of cross-section Figure 2 – Column with notch

according to Eurocode 5 (Russian Building Code [9])

The effective area in case of notches in the cross-section that does not reach the
edge of the element, and if they are more than 1/4 of the area of the section (Fig. 2 –
case A), is:
Aeff  4 / 3 Ant (3)
The effective area in case of notches in the cross-section that are symmetric and
reach the edge of the element (Fig. 2 – case B) is:
Aeff  Ant (4)

5.3. Standard for Structural Design of Timber Structures of Japan

Standard for Structural Design of Timber Structures of Japan [1] comments that
elements with notches (symmetric and asymmetric) have to be designed by taking
into account the effect of the notch. The presentations of experiments’ results of
element with symmetric and asymmetric notches subject to compression demonstrate
the difference in the load bearing capacity. The comparison is between the real
experimental load bearing force and the force determined with the whole area of the
section, and the force determined with the net section (Table 503.2 of [1]) for an
element with slenderness equal to 100. These results show significant differences
between the real and the determined load bearing capacity. The real load bearing
capacity of the element with notch is higher than the element with the net section and
smaller than the element with the whole cross-section.

6. EFFECTIVE LENGTH
The effective length is called 0 according to the Russian Building Code, k
according to the Standard for Structural Design of Timber Structures of Japan and
eff according to the Eurocode 5.

Effectivelength  Factor . Real length (5)

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The factors applied for determining the effective length is called  in Russian
Building Code and 1 in Japanese Building standard.
c
Eurocode do not discuss the determining of the effective length of the element
subject to compression. Porteous and Ross in “Designers’ Guide to Eurocode 5:
Design of Timber Buildings EN 1995-1-1” [8] discuss determining of the effective
length of elements subject to compression. Recommended values for the main
buckling modes are presented. It’s noted that there is a relaxation at the rigid
connections, and the proposed values take into account this feature.
The Building Code of Russia and the Standard for Structural Design of Timber
Structures of Japan are based on the idealized buckling modes.
Ozelton and Baird in Timber designers’ manual [7] also proposed values that are
different from the theoretical.

Table 1 – Main buckling modes with the recommended value for the instability factor

BUCKLING MODES

A B C D
Theoretical value 1,0 0,70 0,50 2,0
Standard for Structural Design of
1,0 0,70 0,50 2,0
Timber Structures of Japan [1]
Building Code of Russia [9] 1,0 0,80 0,65 2,2
“Designers’ Guide to Eurocode 5: Design
1,0 0,85 0,70 2,0
of Timber Buildings EN 1995-1-1” [8]

“Timber Designers’ Manual” [7] 1,0 0,85 0,70 --

American Institute of Timber

1,0 0,80 0,65 2,1
Construction [10]

Note: – Rotation fixed, translation fixed; – Rotation free, translation fixed;

– Rotation fixed, translation free; – Rotation free, translation free

Table 1 presents the main buckling modes with the proposed value for the factor
that gives the ratio between the effective and the geometric length of the element. The

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proposed values from American Institute of Timber Construction [10] are shown too.
These values are also higher than the theoretical ones. The proposed values from
American Institute of Timber Construction for the effective length of elements subject
to compression take into account the lack of perfect fixity in use.
Standard for Structural Design of Timber Structures of Japan gives the theoretical
values for the theoretical buckling modes.
The Building Code of Russia proposed higher values than the theoretical of the
ratio between the effective and geometric length of the elements subject to
compression. These values are the same as the ones proposed by the American
Institute of Timber Construction, with exception for the case of cantilever element
(Table 1, Buckling mode “D”).
The recommended values presented in “Designers’ Guide to Eurocode 5: Design
of Timber Buildings EN 1995-1-1” [8] and “Timber Designers’ Manual” [7] are
higher than the theoretical and higher than the values presented in the Building Code
of Russia, except for case “D”.
These higher than the theoretical values takes into account the relaxation in the
joints and the lack of perfect fixity in use.

7. SLENDERNESS
The slenderness is the ratio of the effective length of an element and the least
radius of gyration of its cross-section. The slendernes is often denoted by  .
eff
 (6)
imin

8. INSTABILITY FACTOR
The slenderness of columns subject to compression has to be less than 150,
according to the Standard for Structural Design of Timber Structures of Japan. The
Russian Building Code prescribes the limits of the slenderness of elements subject to
compression depending on the type of element. For example the maximum
slenderness for columns is 120, for elements that are part of trusses is 150. Eurocode
system does not generally provide elements slenderness limits.
8.1. Standard for Structural Design of Timber Structures of Japan
The instability factor can be determined as follows:
 1   30
  1,3  0,01.  30   100 (7)
3000
   100
2

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According to the Standard for Structural Design of Timber Structures of Japan for
slenderness over 100 the function to determine the instability factor is the theoretical
one, determined by Euler.
8.2. Russian Building Code:
The instability factor can be determined as follows:
2
  
  1,0  0,8     70
 100  (8)
3000
   70
2
The Russian Building Code [9] and Bulgarian Standard for Design of timber
structures effective by 2014 [3] presents same equation for determining the instability
factor. For slenderness over 70 the function for determines the instability factor is the
theoretical one determined by Euler. For slenderness less than 70 the function takes
into account the nonlinear function    .
8.3. Eurocode 5
The instability factor depends on the strength class of the material, not only on the
slenderness. The main parameter is the relative slenderness. The slenderness
corresponding to bending about the y-axis is:

y f c ,0,k
rel , y  (9)
 E0,05
Where
E0,05 – Fifth percentile value of modulus of elasticity;

f c ,0, k – Characteristic compressive strength along the grain.

The instability factor kc , y is:

1
kc , y  (10)
ky  k y2  rel
2
,y

 
k y  0,5 1  c rel , y  0,3  rel
2
,y  (11)

Where  c  0, 2 – for solid timber.

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The slenderness according to Eurocode 5 is based on the critical stresses according

to Euler theory:
 2E I  2E
E   (12)
L2 A 2
fc
rel   (13)
 E 2

E 1
 (14)
fc rel
2

The Euler theory is valid only if there is a linear function between    .

Figure 3 – Instability factor according EC Figure 4 – Instability factor

5, for the different timber strength classes

There are elements subject to compression without a risk of buckling. These

elements are also called short columns. For such elements the instability factor is
equal to 1. According to Standard for Structural Design of Timber Structures of
Japan [1] short column is element with slenderness less than 30. According to
Eurocode 5 [5] the relative slenderness have to be less than 0,30 (this is equal to
slenderness about 20). According to Russian Building Code [9] there are no such
elements.
According to Eurocode 5 [5], the difference between the values for a specific
value of slenderness for the different strength classes is from 0,01 to 0,09 (absolute
values). As a percent the difference is from 1% to 19%. The difference of the
instability factor for the different strength classes for slenderness over 60 is over 10%.
The values of instability factor for timber class C 27 are accepted for the next
comparison.
The difference between the values for a specific value of slenderness, determined
according to the Standard for Structural Design of Timber Structures of Japan [1],
Eurocode 5 [5] and Russian Building Code [9] is less than 0,07 (absolute values). As

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a percent the difference is less than 10%. The comparison between the values of
instability factor determined by the building regulations is presented in Fig. 4.
More precisely the differences are:
 around slenderness 30 – less than 8%;
 for slenderness about 80÷85 – about 8,5%;
 for slenderness over 125 – over 8%.
The instability factor determined by the Standard for Structural Design of Timber
Structures of Japan [1] and by the Russian Building Code [9] for elements with
slenderness over 100 coincides. Eurocode 5 [5] recommends higher values for the
same range of slenderness.

9. CONCLUSIONS
The building regulations have a number of major points of difference in the design
of timber elements subject to compression.
Determining of the effective cross-section of the elements with holes and notches
is one point of dissimilarity. The design of an element with a notch subject to
compression according to the Building Codes has significant differences in the way of
determining the effective cross-section of the element. As the section in most cases is
not symmetric, the real loading condition is a combination of the bending moment
and the axial tension force. The Standard for Structural Design of Timber Structures
of Japan [1] notes that an element with notches that are subject to compression, has
higher load bearing capacity than an element with net cross-section, and that it is
necessary to take into account this complex stress state.
The other point of dissimilarity are the recommendations for determining the
effective length of the elements. The effective length depends on the buckling modes.
Eurocode 5 [5] does not recommend how to determine the effective length of
elements subject to compression. The Building Code of Russia proposed higher
values than the theoretical for the effective length of elements. The Standard for
Structural Design of Timber Structures of Japan [1] recommends the teoretical values
for the effective length of the elements. The higher than the theoretical values for the
effective length of the elements takes account the relaxation in the joints and the lack
of perfect fixity in use.
There are limits of the slenderness of elements subject to copression. The Russian
Building Code [9] and the Standard for Structural Design of Timber Structures of
Japan [1] proposed limits of the slenderness of elements subject to compression. The
Eurocode system does not generally provide elements slenderness limits.
The values of instability factor for specific value of slenderness of the element
according to the building regualtions have differences around 8%.
The results of this examination could be considered preliminary for the
improvement and synchronisation of the global building regulations concerning the
design of timber elements subject to compression.

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ACKNOWLEDGEMENT
The author expresses her gratitude to AUSMIP program for the AUSMIP ✚ Post -
Doc Mobility under the Department of Architecture, Faculty of Engineering,
University of Tokyo, to Associate Professor Kaori FUJITA, Department of
Architecture, Faculty of Engineering, The University of Tokyo and the colleagues
from Takenaka Research and Development Institute for the successful and fruitful
work.

REFERENCES
[1] Architectural Institute of Japan (AIJ), Standard for Structural Design of Timber
Structures - Allowable Strength Design Method, Japan, 2006 (in Japanese)
[2] Building Center of Japan (BCJ), Building Standard Law of Japan, Japan, 2013
(in English)
[3] Standard for Design of timber structures effective by January 2014, 1990 (in
Bulgarian);
[4] European Committee for Standardization (CEN), EN 1990 Eurocode: Basis of
Structural Design;
[5] European Committee for Standardization (CEN), EN 1995-1-1 Eurocode 5:
Design of Timber Structures - Part 1-1: General - Common Rules and Rules for
Buildings;
[6] Hasegava T., Introduction to the Building Standard Law - Building Regulation in
Japan - (Ver. July 2013), Published by the Building Center of Japan, Japan,
2013;
[7] Ozelton E. C., Baird J. A., Timber Designers’ Manual - Third Edition, Blackwell
Science, 2002
[8] Porteous J., P. Ross, Designers’ Guide to Eurocode 5: Design of Timber
Buildings EN 1995-1-1, ICE Publishing (Thomas Telford Ltd.), London, 2013
[9] Ministry of Regional Development of the Russian Federation, Timber Structures
СП 64.13330.2011, Moscow, 2011 (in Russian);
[10] Timber Construction Manual – sixth edition, American Institute of Timber
Construction, 2012;

[673]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
1
Đorđe JOVANOVIĆ
Đorđe LAĐINOVIĆ2
Andrija RAŠETA3

ON SEISMIC ANALYSIS OF CBF AND EBF STEEL BUILDINGS TO

EN 1998, I: THEORETIC BASIS

Abstract: Eurocode 8, based on the concept of capacity design, allows buildings to be designed using
either modal spectral analysis or pushover analysis. Eventhough pushover analysis represents state of
engineering design practice around the world, EN8 does not provide complete information for its
implementation. Practitioners are forced to find those data in other seismic codes, such as USA’s. Brief
review of both of these provisions is presented in the paper, and results of analysis of six-story steel
building with different types of bracing, is presented in companion paper. New trends in detailing, not
mentioned in EN8, and good overall performance of CBF and EBF are stressed and shown.

Кey words: steel braced buildings, CBF, EBF, nonlinear static (pushover) analysis.

O SEIZMIČKOJ ANALIZI ČELIČNIH ZGRADA SA CENTRIČNIM I

EKSCENTRIČNIM SPREGOVIMA PREMA EC8, I: TEORIJA
Rezime: Koncept programiranog ponašanja na kome se baziraju pravila EC8, dopušta upotrebu kako
modalne spektralne analize pri projektovanju objekata, tako i upotrebu "pušover" analize. Iako je
"pušover" analiza poslednjih decenija dobila gotovo uobičajenu primenu u praksi širom sveta, EC8 daje
nepotpune informacije za njeno korišćenje. Ovo praktično usmerava projektante na druge seizmičke
propise, od kojih se izdvajaju Američki. U radu je dat osvrt na ova dva seta propisa, dok je u propratnom
radu prikazana studija slučaja šestospratne zgrade. Istaknuti su novi trendovi u oblikovanju detalja, kao i
efikasnost čeličnih ramova sa spregovima.

Ključne reči: čelične zgrade sa spregovima, centrični i ekscentrični spregovi, pushover analiza

1
MsC asistent dipl.ing.građ, Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka,
djordje.jovanovic@uns.ac.rs
2
Dr redovni profesor dipl.ing.građ , Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka,
ladjn@uns.ac.rs
3
Dr docent,Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka, araseta@uns.ac.rs

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1. INTRODUCTION
Performance-based earthquake engineering has put forward the need for high level
analysis procedures.The choice of the analysis procedure to be adopted depends on
several parameters, such as the importance of the structure, the performance level, the
structural characteristics, etc. In this paper, rules of design to EC8 are presented, but
for comparison, US design code rules are also included [13,25,28], both because of
their complexity and modernity and also the fact that steel braced structures have
bigger tradition and application in USA than in Europe. Besides, extensive list of
literature is aimed to additionally bring closer new findings to domestic practice in
this area.
Steel braced frames can be divided to concentric braced frames (CBF) and
eccentrically braced frames (EBF). In the EC8, CBF are divided again in two groups.
First group is composed of V and inverse V, or "chevron", braces. For structures with
these braces, the biggest allowed behaviour factor (q) is 2 and 2.5 for classes DCM
and DCH, respectively. All other concentric braces fall into second group (X braces,
braces with divided diagonals etc.) and for those, q is equal to 4, regardless of
ductility class. This difference comes from adopted design treatment, adopted in EC8
specifically, which is different for those two groups. In the concept of capacity
design, CBF supply their ductility by yielding of tension diagonals, and inelastic
buckling of compressed diagonals. All other elements are designed to remain in
elastic domain. Strategy of design adopted by EC8 is to model the first group with
both sets of diagonals, while the second group (X braces) is modelled only with
tension diagonals (T/0 model). For second group, different strategy of design,
conditioned the need to limit the relative slenderness of diagonals from below with
the value of 1.3, because of the fact that stronger diagonals would have caused higher
axial forces in the columns, which are not accounted for by this design model. There
is the upper limit for relative slenderness and it is 2.0, to ensure diagonals not to
produce shock effect during load reversal. This limitation does not apply to structures
up to 2 storeys, allowing rods or cables to be used as tension bracing. In addition, in
the literature, it is allowed to omit this rule for the last two stories of any building.
Additionally, in order to provide well distributed yielding over the height of the
structure, overstrength factor Ω for diagonals in all stories, may not vary more than
25% of Ωmin. Behaviour factors given in the EC8 are smaller than those in US codes,
where they amount 5 for all configurations. EC8 does not give the ratio αu/α1 for those
structural types, so it is not possible to confirm higher ductility even by nonlinear
static analysis (NSA).
Eccentrically braced frames appear in several configurations, among which the
most common are D, K and Y braces. The most important element in EBF is seismic
link, which acts as seismic fuse. The aim of design rules is to provide complete
inelastic yielding to take place inside the link. Links can be short, intermediate, and
long, and recommendations is to use short (shear) links because of their efficient
energy dissipation mechanism through yielding in shear. This mechanism, with

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sufficient web stiffening to prevent shear buckling, is characterized by excellent

hysteretic behaviour, significant ductility and great post-elastic overstrength.
Eurocode 8 for this type of structures prescribes q of 4, for class DCM, and 5αu/α1 for
DCH, which by recommendation amounts 6, and with NSA at the most 8. This is
somewhat in agreement with US provisions, which prescribes q=8. It should be noted
that both structure's natural period, and lateral stiffness of EBF is a function of link
length e. The lateral stiffness of EBF covers the range between CBF and moment
resisting frames (MRF), with shorter links corresponding to higher stiffness. In order
to insure structure from concentration of plastification in a single story, same rules
about Ω are prescribed, with the difference in the definition of Ω for EBF - it depends
on type of link and includes post-elastic strain-hardening in amount of 50%.
The particularities of design to EC8 will be addressed in this paper, for both CBF
and EBF. Considering that some of the rules can be loosen using NSA, and also that
this method of analysis became state of the practice throughout the world, for which
EC8 gives incomplete set of parameters, one part of the paper will deal with
application of NSA to steel braced frames.

2. CONCENTRIC BRACES - CBF

In transmitting wind and seismic loads, CBF are considered one of the most efficient
structural systems within steel structures. Their usage in regions with high seismicity
dating from their formation. For long time inherited material ductility of steel was
considered sufficient to ensure satisfying seismic behaviour of objects. After
Northridge and Kobe earthquakes, this stand was greatly changed. New findings
followed by modern provisions have found the necessity of deeper understanding and
insuring post-elastic behaviour of CBF. In the concept of capacity design, in order to
insure elastic behaviour of beams and columns, both qualitative and quantitative
description of post-elastic phases of braces must be defined. The response of CBFs to
significant earthquake loading depends strongly on the asymmetric axial resistance of
the bracing members, which has a complex cyclic inelastic behaviour due to the
influence of the following physical phenomena: yielding in tension, buckling in
compression, post-buckling deterioration of compressive load capacity, deterioration
of axial stiffness, low-cycle fatigue fractures at the plastic hinge regions, and the
Bauschinger effect [19]. Important information is that after buckling, in the
succeeding cycles, diagonals retain resistance in compression in amount of 30% of
buckling load. Since diagonals are loaded alternately by compression and tension, it is
of great importance to prevent failure of the member in place of plastic hinge, i.e. in
the middle of the brace.
It is concluded that basic parameters influencing ductility of CBF, are relative
global and local slenderness of diagonals. According to EC8 local slenderness is
calculated the same way as for static loading, so for certain ductility class, only
section class is demanded (I for DCM, and II for DCH). In [29] this condition is
somewhat tightened, considering dynamic nature of loading.

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For bracing members of CBF, hollow square or rectangular sections are often
used, and there is extensive research on their behaviour in CBF during earthquake
[17,23]. For hollow sections, especially rectangular, fracture occurs earlier than in
most other sections, because of the stress concentration in corners. Even though,
because of their high resistance in compression, they are usual choice of profiles for
diagonal members. Hollow sections can be filled with concrete, in which case rules
on local ductility do not apply. Global slenderness is prescribed in EC8 as mentioned
earlier, and that is the biggest difference between European and US code. In [29],
slenderness is almost in all cases demanded less than 120. Meanwhile, according to
those two sets of provisions, columns are designed to completely different set of
forces. Problem is more complex than stated. Already mentioned Ω factor, beside it is
not capable of completely insuring uniform distribution of plastic demand along the
building height, in combination with stipulation on slenderness, complicates design
with commercial sections greatly. In the paper [3], it is shown that for certain building
heigths and beam spans, it is impossible to satisfy conditions of EC8 using
commercial sections. In addition, it is presented that EC8 design procedures often
lead to oversized structural solutions [7]. Many researchers proposed innovative
methodologies of design [3,7,11,12] in order to preserve traditional cost-effectiveness
of CBF, which is "greatly undermined by application of the EC8 design procedure"
[30].
Besides aforementioned difficulties in design, which is iterative by its nature,
designer will most probably need a spectrum of different sections for braces, to
comply with demands. It is unusual that connection design is almost not mentioned in
EC8. Usual practice of connection design was based on findings of [1], dating back in
1986. The most important connection is one between diagonal and column-beam
joint. The idea was for plastic hinge to develop inside the zone in gusset plate. This
zone is perpendicular to diagonal and its minimum width is twice the plate thickness
(Figure 1a). Recent research [18,27] refers to usage of thinner gusset plate and
elliptical zone of plastic hinge. The elliptical hinge zone is eight times the thickness
of the gusset (Figure 1b). Crack initiation invariably occurs in gusset plate
connections because of substantial deformations experienced by the gusset plate.
Design strategy of EC8 is to design connections stronger than the brace member, but
the gusset plate will yield because of the deformations caused by brace buckling,
regardless of the conservativeness of its design. In light of that, the connections
should be designed to be stiff enough and strong enough to fully develop the brace
capacity in compression and tension, but excessive strength and stiffness are
undesirable in that they reduce the inelastic deformation capacity of the brace and the
CBF system [27]. New, proposed procedure encourages use of thinner, more compact
gusset plates, which facilitate end rotation caused by buckling of the brace. These
recommendations are not yet included in [29], which is far ahead of EC8 considering
connections. It must be mentioned that in US exists a multitude of prequalified
connections, experimentally tested and simple to use in everyday practice. Another
specific connection is intersection of two diagonals in X brace. In this brace, tension
diagonal provides a support for compression diagonal [23]. Standard connection with

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splice plate (knife plate) leads to buckling of only half of compressed diagonal, and it
is favourable than other types, like sandwich splice connection, where torsional
deformation of diagonals are inevitably transferred to gusset plate at the end of the
member.

Figure 1 – Details of connections for CBF: a)b) buckling out of plane,c)buckling in plane

3. ECCENTRIC BRACES - EBF

This system of steel braces is almost entirely based on work of E. Popov, of which
some are [14,24,25].Even though in [24,25] short or shear links are recognized as the
most efficient, others are used too. For one of the biggest advantages of this system is
the fact that after a strong earthquake, only the link needs to be replaced. Although,
only for Y configuration of EBF link is a separate part, which is easy to replace, while
for other configurations, link is integral component of the beam. Nevertheless, the
biggest advantage of EBF with short links is dissipative behaviour, obtained by very
stable and efficient mechanism - shear yielding. This system of braces combines
ductility of MRF with stiffness of CBF. Eurocode prescribes aforementioned rules on
link length, limitation of plastic rotation of link, and number of web stiffeners for
prevention of local web buckling, all to ensure desired capacity design of EBF.

Figure 2 – a)M-V interaction of the link, b) detail of brace-to-beam connection in K EBF

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Overstrength plays a paramount role in the application of capacity design

principles [21]. Non-dissipative members must be able to withstand forces transmitted
from the link, after the link has strain-hardened. The sources of capacity reserve of
the link are mainly due to strain hardening, but can also come from interaction of
flanges in shear resistance of the link. Post-elastic hardening, since the invention of
EBF, had been considered to be 50%, i.e.Vu = 1.5Vp, albeit later researchers found this
factor both smaller [22], and considerably higher [6], than this value. It was later
concluded that in large build-up shear links, with heavy flanges, higher overstrength
factor is reached. Crucial element for comparing these findings is the way shear
resistance is defined: in EC3 it already includes contribution from the flanges, while
in [29] and most of the research, it does not. After all, it is concluded that an
overstrength factor of 1.5, which forms worldwide basis of capacity design provisions
for EBFs, appears reasonable for links constructed by means of typical rolled profiles
[21]. In such a way, in EC8, Ω for short link is defined as:
(1)
This factor will have decisive role in design of non-dissipative members -
diagonals, beams and columns, and therefore its influence on total structural weight
premium is essential. It is omitted in EC8 to emphasize that short links, which are rare
example of M-V interaction in buildings, do not comply to usual interaction rule
given in EC3, but to Neal's expressions:
| |
( ) ( ) | |

| | (2)
Additional confusion is introduced by one of rare examples of EBF design given
in [2], where this interaction (EC3) is introduced. By doing so, unnecessary
overstrength of links is caused, and it is transmitted to whole structure (Figure 2). The
angle of diagonals of EBF with D and K configurations greatly affects axial force in
the beam [20], and therefore small angles should be avoided. Most often beams
outside of the link are designed as composite (steel-concrete), precisely because of
high axial forces. As opposed to adopted design concept, that should be able to secure
uniform demand on all links, there are many researches [4,14,20,21] suggesting new
design based on energy concept and rigid-plastic analysis of EB-Frame. The fact that
future design concept will be precisely performance based design, testifies the
document FEMA 450, which brings forward research plan in order to accomplish this.
The fundamental reason is that present-day provisions are based on elastic design,
which does not guarantee simultaneous activation of links on all stories during
earthquake. This is precisely the reason why [29] gives altered overstrength factors
for beam and column design, camparing with EC8. Namely, internal forces in beams
and columns should be increased by 38% (against 50% in EC8) because post-elastic
hardening of all links on all stories is not to be expected, while diagonals are

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calculated with 52% increased action effect. Nevertheless, these enlargements are
derived by assuming 50% strain hardening.
While connections in CBF are usually pinned (otherwise structural system is
named "combined"), in EBF position is fairly different. In K type, diagonal members
can be connected simple or fixed to beam and link, with some advantage of fixed
connection, because after possible plastification of the beam, additional bending
moment could be transferred to diagonal. Bending moments on the end of the link
have same value and different sign, and connection with diagonal should be designed
as in Figure 2. Gusset plate is strengthened with additional bottom flange because of
the flexural resistance, but more importantly, because of plate buckling. In D type,
bending moments on two sides of the link are not the same, even after plastic hinging
took place. Values of this moments can be found in [25]. In Y configuration, there is
no consensus which side of the link is fixed, even though [8] clearly indicates with
figure, that the link is fixed to the beam, and pinned to diagonals. Beams can be
connected to columns with both types of connection, which is a difference [29] is
recognizing, while in the EC8 design concept, fixed beams would constitute
combined frames, even though they are not defined as such.

4. NONLINEAR STATIC ANALYSIS - NSA

This method of analysis has gained in significance over the last decades and more
often is considered standard engineering practice. Probably, most deserving is set of
documents FEMA, out of which only few are mentioned in the list of literature
[13,26], even though there are 59 of them (9 for new buildings, 19 for retrofitting of
existing buildings), against 2 documents in Eurocode. Therefore, the practitioner is
compelled to use recommendations included in FEMA documents, even when design
is accomplished according to EC. Still, considering difference in definition of loading
(ASCE7 vis-a-vis EC1), especcially concerning loading on columns, this can be the
source of misinterpretations. NSA is usually used as verification tool for structure
already designed, in order to better establish inelastic behaviour of structure, and
perhaps to notice undesired plastic configurations. It needs to be said that only
advantage of NSA, over dynamic response history analysis (NRHA), is that former is
cheaper, i.e. faster, and that engineers are generally not familiar with the latter.
NSA or pushover analysis is modern version of classical collapse analysis. It is
important to state, that static pushover analysis has no rigorous theoretical foundation
[15]. Two assumptions of this analysis are extensive approximations. The assumption
that the response of a multi-degree-of-freedom system is directly related to the
response of an equivalent single-degree-of-freedom (SDOF) system, is not accurate
enough when apart from the fundamental mode, higher modes may contribute to the
response [16]. Second assumption that fixed lateral load pattern represents a good
approximation of inertial forces induced by ground motion, does not include
plastification of some members, and its influence on modification of dynamic
properties of the structure. Many researches, collected in [12], testify about

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inaccuracy of NSA. Researchers have, recognizing efficiency of NSA in every day

practice, proposed different modifications of this method. Among many, few
directions of pursuit emerge. Multimodal NSA (MMP) includes the response of other
modes of vibration in the lateral load profile [28]. Modal pushover analysis (MPA),
developed by Chopra and Goel, practically combines pushover curves for first few
modes [6]. Adaptive modifications of NSA are based on calculating natural
frequencies of the structure, after every change in lateral stiffness, and in accordance
to it differs lateral load distribution. The completely different approach comes from
methods based on displacements.
Eurocode prescribes procedure with two different lateral load patterns, uniform
and mode shape pattern. Target displacement, which should render deformations and
inelastic distribution in structure during ground motions corresponding to design
spectra, is calculated by N2 method [9]. In US provisions two different methods for
calculating target behaviour coexist, namely Coefficient Method, proposed by FEMA,
and Capacity Spectrum Method specified in ATC40. Results of these three methods
are presented in companion paper.
In the end of this short overview, it should be stated, that if implemented with
judgement, and with due considerations given to its many limitations, the pushover
analysis will be great improvement over presently employed elastic evaluation
procedures [15].

5. CONCLUSION
Rolls of analysis, design and calculation of steel braced frames to EC8 are
summarised, along with their particularities. Further, necessity and advantages of
consulting other provisions for seismic design of steel buildings are stressed.
Necessity emerges with application of nonlinear static analysis, but also with some of
configurations unrecognized by EC8, such as combined MRF and EBF. However, out
of many aspects, the most important is connection design, which initially was a cause
for new design approaches, and importance of which cannot be exaggerated in those
structural systems. In this paper, an attempt to select most important aspects,
principles and rules of design is made, while for more complete overview of
particularities and state of art, researches in this subfield of seismic design are cited in
literature list.

ACKNOWLEDGEMENT
The work has been done within the scientific research project TR 36043
"Development and application of a comprehensive approach to the design of new and
safety assessment of existing structures for seismic risk reduction in Serbia", which is
funded by the Ministry of Science of Serbia.

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[23] Palmer KD et al. 2012. Concentric X-braced frames with HSS bracing. Int J
Steel Struct 12: 443-459.
[24] Popov EP, Engelhardt MD, 1988. Seismic eccentrically braced frames, J Constr Steel
Res: 321-354.
[25] Popov EP, Kasai K, Engelhardt DM, 1986. Advances in design of eccentrically braced
frames, Pacific Structural Steel Conference, Auckland.
[26] Prestandardand Commentary for the Rehabilitation of Building (FEMA-356)
2000. Washington, DC: Federal EmergencyManagementAgency.
[27] Sabelli R, Roeder CW, Hajjar JF 2013. Seismic Design of Steel Special
Concentrically Braced Frame Systems, Gaithersburg: National Institute of
Standards and Technology.
[28] Sasaki KK, Freeman SA, Paret TF. Multimode pushover procedure (MMP)—a
method to identify the efects of higher modes in a pushover analysis 1998.
Proceedings of the 6th U.S. National Conf. on Earthq. Eng. Seattle,
Washington.
[29] Seismic Provisions for Structural Steel Buildings, 2005. AISC.
[30] Tremblay R. 2002. Inelastic seismic response of steel bracing members. J Constr
Steel Res 58: 665–701.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
1
Đorđe JOVANOVIĆ
Đorđe LAĐINOVIĆ2
Andrija RAŠETA3

ON SEISMIC ANALYSIS OF CBF AND EBF STEEL BUILDINGS TO

EN 1998, II: CASE STUDY

Abstract: For a long time inherited material ductility of steel was considered sufficing to ensure
satisfying seismic behavior of steel objects, which proved to be incorect. Being adopted EN8 recently,
rules of seismic design are modernized, but in the field of steel buildings, they are still one generation
behind the US code. In this paper, design process for three six-story steel buildings with different types
of braces, is shown. Modal analysis, along with pushover analysis to EN8, are used with reference to US
code. Results od design, along with relative story drifts, and overstrength factors are presented for two
analysis.

Кey words: steel braced buildings, CBF, EBF, nonlinear static (pushover) analysis.

O SEIZMIČKOJ ANALIZI ČELIČNIH ZGRADA SA CENTRIČNIM I

EKSCENTRIČNIM SPREGOVIMA PREMA EC8, II: PRIMER
Rezime: Dugo se smatralo da je nasleđena duktilnost materijala dovoljna za zadovoljavajuće ponašanje
čeličnih objekata pri zemljotresu, što se pokazalo netačnim.Skorašnjim usvajanjem Evrokoda 8, pravila
aseizmičkog dimenzionisanja su osavremenjena, no u sferi objekata sa čeličniim okvirima ona i dalje
ostaju generaciju iza Američkih propisa. U radu je prikazanodimenzionisanje tri šestospratne čelične
zgrade sa različitim tipovima spregova. Korišćene su modalna, ali i „pushover“ analiza prema EC8, uz
osvrtanje i na Američke propise. Prikazani su rezultati dimenzionisanja, relativna spratna pomeranja,
“pushover“ krive, kao i faktori predimenzionisanja prema ove dve analize.

Ključne reči: čelične zgrade sa spregovima, centrični i ekscentrični spregovi, pushover analiza

1
MsC asistent dipl.ing.građ, Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka,
djordje.jovanovic@uns.ac.rs
2
Dr redovni profesor dipl.ing.građ , Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka,
ladjn@uns.ac.rs
3
Dr docent,Departman za građevinarstvo i geodeziju, Fakultet tehničkih nauka, araseta@uns.ac.rs

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1. INTRODUCTION
Adopting Eurocode 8 (EC8) in Serbia, seismic design of steel braced buildings has
changed drastically. Although rarely employed, both in literature and in domestic
practice, these systems are considered highly efficient amid seismically resistant
structures. Collection of clauses of EC8 treating steel braced structure, number of
rules they need to conform to, so as the literature [1,3-5,7] aimed to clarify and
comment those rules, are not extensive. On the other hand, researches and
publications on these systems are considerable and often impose adjustments of
technical provisions. In companion paper, those rules prescribed by EC8 are
described and commented, while in this paper, they are applied on design of six-story
steel braced building.

2. SIX-STORY STEEL BRACED BUILDING

Six story building, from Figure 1, is studied and designed according to instructions
of EC8. Raster of columns is 9x9m, story heights are 4m and lateral rigidity is
provided by pair of braces (because of robustness) on every facade of the building.
Still, the main difference between stiffness in two main horizontal directions is due to
the fact that braces in Y direction are positioned in two neighboring spans. All beams
are simple, and columns are fixed in foundations.

Figure1 – Subject building – Plan view and studied types of braces shown for one floor

For the purpose of design, following parameters are adopted: ag=0,2g, soil type B,
importance class II. For dissipative elements, steel grade S235 is used, and for others
S355, thus reducing γov to value of 1.0. Self-weight loading is adopted in amount

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g=5kN/m2, while p=2kN/m2. Considering that area of one story is 972m2, and that
ψEi=0,8, total seismic mass of one floor is 679t. Imposed loading on the roof is less
than on the usual floor, but mass of equipment on the roof is adopted so that the mass
of every level is the same. Three-dimensional model of structure is built in software
SAP2000. On floor levels, joints are connected by rigid diaphragm, but in a way not
to include beam joints, so that axial loading of beams is unrestrained. Masses of
floors are assigned as lumped, eccentrically placed relative to the stiffness of rigidity,
with eccentricity being 5% of parallel length of the building. Besides masses in two
horizontal directions, mass inertia moment is applied. This approach of modelling
torsion effects is possible, since there is no interaction between two lateral rigidity
systems. Otherwise, torsion effects cannot be modelled this way, except more loading
scenarios is used. Also, since frames of different orientation do not interact, and
corner columns are not parts of both braces, there is no need to combine earthquake
actions with any of prescribed procedures in EC8. Even though this is not stated
explicitly in EC8, besides being logical, it is explicitly listed in [5].
Case study includes three different systems of braces in aforementioned structure.
First are concentric braces of X configuration (CX), second are also concentric
braces, but „chevron“ (CV), and third are eccentric braces of Y configuration (EY).
First group (CX) is treated specifically in EC8, since T/0 model is demanded, while
for NSA both diagonals are modelled, therefore its results are more than welcome for
this type of braces. Second system is granted with unusually small behaviour factor
and different principle of modelling (T/C model is used). Third type, although less
represented in researches, is taken to represent EBF, because it produces smaller
demands on beams, and somewhat higher architectural freedom. Structure is
calculated using modal spectral analysis (MSA) and designed according to EC8 rules,
and then NSA is conducted, and results are compared. For MSA, type 1 of response
spectrum is used, and behaviour factors of 4 for CX and EY, and 2.5 for CV, which is
DCM class of ductility for first two, and DCH class for CV because of already small
prescribed behaviour factor. Non-dissipative members are designed to Eurocode’s
rule for combination of action Q:
(1)
Nonlinearity in NSA is introduced through earlier defined plastic hinges [10].
Parameters of this hinges can be assigned either by stress-strain relation, or by force-
displacement ratio. Quantified force-displacement parameters, not provided in EC8,
are given in [8], and presented here. In EN 1998-1-3 only acceptance criteria
parameters for adopted limit state are given. It is possible to model plasticity using
fiber hinges, when for every fiber stress depends on preselected stress-strain relation.
This approach is recommended rather for columns and beams, if there is moment-
axial force interaction, while for seismic link, especially short link, this can be
imprecise. Ductility in short links depends on number of web stiffeners, and values in
Table 1 are obtain through many experiments, results of which partially deviates from
theoretic predictions. Parameters in Table 1 for CBF diagonals depend on Δt i Δc, that

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stand for displacements on onset of yielding, and on onset of buckling, respectively.

On the other hand, parameters a and b for short links are given in radians, demanding
plastic rotation of link to be calculated ahead. It is given by:

(2)
where:
Ke–stiffness of the link, which consists of flexural and shear parts. Expressions
are well-known, but are also provided in[8].
Parameters for columns and beams are also provided in [8], but since they are
dependent of axial force in a member, they are not shown here because of concision.
NSA is performed on the case study using both fiber and hinges with these
parameters, and hinge results obtained are almost identical. Post elastic hardening, not
given by parameters a, b and c, is allowed to be taken as 3%, except for short links,
where 6% is allowed.

Figure2 – Definition of input parameters for NSA – force-displacement ratio (left) and
acceptance criteria (right)[10]

Table 1 –Values from Figure 3 according to FEMA356

a b c IO LS CP
tension diagonal 11Δt 14Δt 0,8 0,25Δt 7Δt 9Δt
compressed diagonal 0,5Δc 6Δc 0,35 0,25Δc 3,25Δc 5Δc
short link 0,15rad 0,17rad 0,8 1,5 9 13

3. RESULTS
In the following figures, results of analysis on subject building are shown. Beams’
and columns’ sections are not shown here, since they do not differ between buildings.
All outer columns have sections HEB400 below the middle of forth floor, and
HEA400 above, which was dictated by non-seismic combinations, and satisfied
seismic ones for in all cases. Beams in frames with braces are HEM260 in X
direction, and HEB 260 in Y. Also, design is dictated by non-seismic combinations.
Such big span of beams is adopted deliberately, because the same span is used in [2].

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For this span, composite design would be more economical, but steel beams are kept
beside regularity in material, because of the fact that there are no recommendations
about input parameters for hinges of composite sections.
For EY building, adopted sections and length of links height wise is given in Table
2. All links meet confines for short links. These sections are found from results of
MSA, with fulfillment of all mentioned rules given in EC8. Factors Ω are shown in
Figure 4, where they are compared to one obtained with NSA. All diagonal members
have hollow square section 150x150x8.

Table 2 – Adopted sections for EY by floors for X direction

floor/member 1 2 3 4 5 6 7

link section-X dir. HEM280 HEM280 HEM280 HEB360 HEB320 HEA320 HEA220

link section-Y dir. HEM280 HEM300 HEM280 HEM280 HEB360 HEB280 HEA240

link length-X,Y 0,45m 0,45m 0,45m 0,45m 0,45m 0,45m 0,26m

For CX and CV sections of diagonals are shown in Table 3. It is evident that

whole spectrum of different sections is needed to simultaneously satisfy conditions on
slenderness and overstrength. For braces of CX building, desirable ratio of area and
slenderness possess both channel and rectangle hollow sections. It was not possible to
satisfy EC8 conditions using channel commercial profiles.

Table3 – Adopted sections of diagonals for CX and CV by floors

floor/member 1 2 3 4 5 6 7
CX braces X 80/80/3.6 160/80/6.3 140/80/6.3 120/80/6 100/80/6.3 120/80/4 100/80/3
CV braces X 120/120/6 120/120/8 140/140/6.3 160/160/5 140/140/5 90/90/5 90/90/3.6
CX braces Y 140/80/8 140/80/8 140/80/8 140/80/6.3 120/80/6 120/80/5 100/60/4
CV braces Y 150/150/8 150/150/8 150/150/8 160/160/6.3 140/140/6.3 90/90/8 100/100/4

In Figure 3 is shown comparison on relative story drifts obtained by MSA and

NSA. Results of NSA for modal distribution of lateral forces are denoted with
“-mode”, while “-uni” stands for uniform distribution. For EY and CV building MSA
underestimates relative story drifts, while for CX it overestimates them. It is also
evident from this figure, that the lateral pattern intensifies yielding and total
displacement similar to its shape. That is the reason for bigger relative drift on the top
of the building for modal pattern, and higher drifts in the bottom for the uniform
pattern. Pushover analysis reveals potentially weak second floor for EY building in Y
direction.

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sprat sprat sprat

EY X-mode CX X-mode CV X-mode
7 7 7
X-uni X-uni X-uni
Y-mode Y-mode Y-mode
6 6 6
Y-uni Y-uni Y-uni
MSA-X MSA-X MSA-X
5 5 5
MSA-Y MSA-Y MSA-Y

4 4 4

3 3 3

2 2 2

1 [cm] 1 [cm] 1 [cm]

0 2 4 6 8 0 1 2 3 4 0 2 4 6

Figure 3 –Relative story drifts for different directions and analysis (MSA and NSA)

Overstrength factors are as shown in Figure 4. Factors are calculated as prescribed

in EC8, so when section’s resistance is fully utilized, Ω is 1.0 for CX and CV, and 1.5
for EY. As expected, results of NSA give smaller Ω than MSA. Values below 1.5 for
EY signalize development of post-elastic deformations in links, and strain hardening.
Value of 1.0 would mean that maximal plastic resistance is reached. Obviously, this is
not the case, so comment onFigure4 remains in the field of damage limitation. For
CX building comparison is given for tension diagonals. On floors I, IV, and V,
stresses in diagonals reached yielding point, while all compressed diagonals
developed plastic hinges, and underwent stiffness degradation after buckling. None of
the plastic hinges in beams was activated, nor in columns, except in the bottom of
columns. Shortly, NSA demonstrated satisfying behaviour of structures.

sprat
EY MSA-X
sprat CX MSA-X
sprat
CV MSA-X
7 7 7
MSA-Y MSA-Y MSA-Y
6 NSA-X 6 NSA-X 6 NSA-X
NSA-Y NSA-Y NSA-Y
5 5 5

4 4 4

3 3 3

2 2 2

1 1 1

0 Ω 0 0 Ω
1,2 1,4 1,6 1,8 2 0,8 1 1,2 1,4 1,6 1,8 0,8 1,3 1,8

Figure 4 – Ω factors according to modal spectral analysis and pushover analysis

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Pushover curves are shown in Figure 5. Target displacements according to N2,

capacity spectrum method (ATC40), and coefficient method (FEMA356) are marked
on the curves. Coefficient method is considered approximate in the US practice, and
usually ATC40 method is recommended. Capacity spectrum method, and N2 method,
obviously give similar results. In the figure, high ductility is noticeable, especially for
EBF. Also, large hardening (overstrength) factor is apparent for all types of braces.
Values in Figures 3 and 4 are obtained for target displacement obtained by N2
method. Target displacement attained by other methods is shown for comparison.

EKS-X CBF-X
Vb [kNx1000]
EKS-Y 6,0 CBF-Y
6 CV-Y
ATC-40 CV-X
5,0
5 CV-Y
FEMA 356
4,0 ATC-40
4 N2
N2
3 3,0

2 2,0

1 1,0

0 0,0
u [m]
0 0,5 1 1,5 2 0,0 0,5 1,0 u [m]

Figure 5 – Pushover curves with specified target displacements obtained by N2, ATC40 and
FEMA356

4. CONCLUSION
In this paper, advantages and weaknesses of design of steel braced frames,
according to new current provisions, are stated. Concept of design differs greatly
from one used in former provisions. Eurocode still, besides its evident superiority to
SRPS, remains incomplete, and in some fields vague. Here, connections emerge as
most important field, with not only calculation prescription missing, but
recommendations, types and parameters for designing them. Further, even though in
the world NSA has become everyday practice, EC8 does not provide enough
parameters for its use. In this and companion paper input parameters for analysis of
steel braced buildings, recommendations and experiences are collected and presented.
On case study, results of multimodal spectral analysis and pushover analysis are
shown. On EY and CV example buildings, significant divergence in relative story
drifts between MSA and NSA is recognized. Besides, on the example of EY building,
extraordinary ductility of eccentric braces is demonstrated, even though they have
never gained acceptance in domestic practice. Stable dissipative mechanism of those
systems makes them one of the most desirable in seismic regions.
Comments about uneconomical design of steel braced buildings to EC8 are only
partially demonstrated. Even though pushover analysis indicated significant amount
of reserve in dissipative members, assertion on conservativeness of design is not

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proven, especially for EBF. Remains evident the fact that diapason of profiles is
needed in order to satisfy provisions, which wasn't the case with previous code.
This paper is a part of ongoing research and authors are aware of deficiency of
nonlinear plastic analysis, in order to verify NSA results. However, nonlinear
dynamic analysis is not usual for this types of structures, nor its usage is closely
defined in EC8. Also, parameters for modelling nonlinearity are the same as for NSA.

ACKNOWLEDGEMENT
The work has been done within the scientific research project TR 36043
"Development and application of a comprehensive approach to the design of new and
safety assessment of existing structures for seismic risk reduction in Serbia", which is
funded by the Ministry of Science of Serbia.

REFERENCES

[1] Bisch et al., 2012. Eurocode 8: Seismic Design of Buildings - Worked examples.
Ispra: European Commission Joint Research Centre.
[2] Brandonisio G et al. 2012. Seismic design of concentric braced frames. J Constr
Steel Res 78: 22–37.
[3] Eurocode 3 : Design of steel structures – Part 1-1 : General rules and rules for
buildings, 2004. Brussels: European Committee for Standardisation.
[4] Eurocode 8: Design of structures for earthquake resistance - Part 1: General
rules, seismic actions and rules for buildings. 2004. Brussels: European
Committee for Standardisation.
[5] Fardis M et al. 2005. Designer’s guide to EN 1998-1 and EN 1998-5. London:
Thomas Telford.
[6] Improvement of Nonlinear Static Seismic Analysis Procedure (FEMA-440) 2005.
Washington, DC: Federal Emergency Management Agency.
[7] Manual for the seismic design of steel and concrete buildings to Eurocode 8.
2010. London: The Institution of Structural Engineers.
[8] Prestandard and Commentary for the Rehabilitation of Building (FEMA-356)
2000. Washington, DC: Federal Emergency Management Agency.
[9] Seismic Provisions for Structural Steel Buildings, 2005. AISC.
[10] Wilson E, 1998. SAP2000 Three Dimensional Static and Dynamic Finite
Element Analysis and Design of Structures V7.40 N, Berkeley: Computers and
Structures Inc.

[691]
 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
1
Kiril STOJANOVSKI
Rüdiger HÖFFER2
Elena DUMOVA-JOVANOSKA3

DESIGN WIND VELOCITY IN THE R. MACEDONIA -

PREPARATION FOR IMPLEMENTATION OF THE EUROCODE
Abstract: The National Annex to the EN1991-1-4 first of all should provide parameters that are
geographically dependent, such as the design wind velocity map. To evaluate the reference wind
velocity, methods for extreme value analysis are used, based on data of continual historically maximal
annual velocities. The orography and the terrain roughness of the surrounding terrain and their influence
to the measured data must be taken into account for normalization of the obtained data. In the Republic
of Macedonia valuable data are available for 8 measuring points and the initial values are estimated.

Кey words: EN 1991-1-4, extreme value analysis, influence of the terrain, reference wind velocity.

PROJEKTNA BRZINA VETRA U REPUBLICI MAKEDONIJI –

PRIPREMA ZA UVOĐENJE EUROKODOVA
Rezime: Nacionalnim Dodatkom propisa EN 1991-1-4 pre svega treba da se obezbede parametri koji su
geografski zavisni, kao što je karta brzine vetra. Za određivanje referentne brzine vetra koriste se metode
za analizu ekstremnih vrednosti na bazi kontinuiranih podataka istoriskih maksimalnih godišnjih brzina
vetra. Na merene vrednosti uticaj imaju orografija i rapavost okolnog terena, šta mora da se uzme u obzir
pri normiranju dobivenih podataka. U Republici Makedoniji za ovaj cilj postoje upotrebljiva merenja sa
8 stanica, koji podatci su dobiveni i proračunate su prvične vrednosti.

Ključne reči: EN 1991-1-4, analiza ekstremnih vrednosti, uticaj terena, referentna brzina vetra.

1
MSc, IECE, Drezdenska 52,1000 Skopje, Macedonia, kiril.stojanovski@iege.edu.mk
2
Prof. PhD, Department of Civil and Environmental Engineering, RUB, Germany, ruediger.hoeffer@rub.de
3
Prof. PhD, FCE, University “Ss. Cyril and Methodius”, Skopje, Macedonia, dumova@gf.ukim.edu.mk

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1. INTRODUCTION
Wind engineering is a relatively new field and understanding of its problematic is
developing fast. Without criticizing the previous work and the existing regulations,
improvement of the norms is a logical consequence of the improved knowledge.
For the design of structures in the Republic of Macedonia the wind loads are seen
as a „secondary“ action, complicated for calculation and no so important for the
structural elements. Considering the traditional „heavy“ structures this point of view
is not so far from the truth, but for light, contemporary and spacious structures, wind
should definitely be taken seriously into account. The technical regulations from the
year 1948 and the year 1964 are still valid and the Yugoslav standards from the year
1991 are not officially accepted, so it is left on the designers to decide how they are
going to work, which leads to construction of structures and their parts with different
reliability.
At the end of the year 2014 almost all full members of the European Committee of
Standardization (CEN) have accepted the new Eurocodes followed by National
documents of application, while the Republic of Macedonia has been referred to as a
country that has not delivered applicable information yet [5].
EN1991-1-4 defines the characteristic values for wind influence for the biggest
part of the land-based structures, as for the complete structure, so for its parts and
elements attached to it. The main part of the regulation cannot be applied without a
National Annex (NA) issued by an institution authorized by the state in which the
structure will be built. NA should acquire information and instructions which are
geographically depended, such as the design wind velocity map, national choices of
National Values, Nationally Determined Parameters (NDP), choices where the
common approach is not definitive, as well as rules to meet the local regulation and
laws for construction. In the part EN 1991-1-4 for approximately 70 parameters the
possibility for national choice is left and for almost all of them recommended values
or procedures are suggested. The bigger states, who are using the national regulations
for a longer period of time and have already invested a lot in own research, are using
the biggest part of the possibilities given by the norm to make the new Eurocode
closer to the previous national standards. The common approach is that the smaller
countries are accepting almost all of the recommended values and procedures from
the main document, without additional investments in research.
The wind velocity is a parameter characteristic for a certain territory,
geographically and climate dependent, so it is left as obligation for each country to
define it. The Republic of Macedonia first of all should prepare the necessary
parameters and all the rest can be a subject of further scientific considerations. The
goal of the research, where from this paper derives, is to prepare a foundation for the
national wind map and to determine the significance of the obtained values for the
safety and reliability of the structures.

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2. WIND LOADING IN THE EUROPEAN REGULATION

The wind pressure oscillates in time and in position through the external surfaces
on the structure on a complex and random way. The resulting wind loading on a
certain structure is a combined influence of the local wind climate, local wind
exposure, the aerodynamic characteristics of the structure form, the possible
amplification of the influence due to the resonant wind-caused oscillation, as well as
the criteria for assessment of acceptance of the estimated wind influence. Since the
introduction of the „wind-loading chain“ concept [2], it was widely accepted for
assessment of the unsteady wind-loading on different types of structures. In this part
of the research, the focus is on the first part of the chain, the wind-climate.
The Eurocode follows this principle and uses simple methodology to show the
complex processes of wind influences, using mathematical models. The design of
sensitive structures in principle means avoiding the opportunity for aeroelastic
response. Using the dynamic factor cd the Eurocode simplifies the dynamic model and
allows a static calculation, where this is acceptable. The real pressure distribution and
forces are shown with simplified value distribution, which are giving loading on the
structure equal to the extreme wind-effects.
The „characteristic“ wind loading is given as a „variable fixed action“ defined in
EN-1990, except for big openings where it is taken as „occasional influence“. The
„characteristic“ values of the wind loading are values with annual risk of exceeding of
0,02 for each year in which the structure is in use.
The principle of the peak factor model, used as basis for calculation in the EN-
1991-1-4, is that the mathematical quasi-static influence during wind gust or the
dynamic response of the structure can be described with a mean, constant part and an
additional turbulent, variable part. The ratio of the turbulent part and the mean one is
given with the peak factor, g, which depends from the size of the gust and from the
characteristics of the structure.
The mean part of the wind velocity pressure at a particular height z depends on the
specific air mass and the mean wind velocity on that height.
1
qm     ( cdir  cseason  cr  co )2  vb2,0 (1)
2
Where:
cdir is the factor of the direction and
cseason is the factor of the season.
cr is the coefficient of the surrounding terrain roughness.
With the exact determination of these factors optimized structures with unchanged
safety can be obtained. The seasonal factor can be significant only for temporary or
seasonal structures. A recommended value of 1,0 is given in the Norm, which in this
work will be accepted. With this assumption, the basic wind velocity vb is equal to the
fundamental basic wind velocity vb,0.

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This coefficient depends on the terrain roughness in the direction where from the
wind comes and on the referent height over the earth surface. The terrain parameters
are defined for all five terrain categories given in the regulation. In order to achieve a
stable wind profile an approaching length of app. 200 km is needed, which is difficult
to achieve. Because of this, some countries give their own procedures for
determination of the roughness coefficient. The coefficients calculated according to
the recommendation in the main part of the regulation are later on used for
normalization of the measured wind velocities.
cо is the orography coefficient,
This coefficient should be taken in concern when it increases the mean wind
velocity for more than 5%. In the regulation, a method for calculation of the wind
acceleration throughout hills and cliffs in two dimensions is given, but not for
assessment of the acceleration around the sides of the geographical obstacle or due to
the canalizing of the airflow in the valleys. Key parameters for the orography factor
are the slope of the exposed side of the hill and the position of the structure in relation
to the crest. The application of these recommendations requests from the user to
determine the intersection of the orography element along the wind line and to present
the obtained form with an appropriate triangle form. This procedure is important for
the calculation because the increase of the wind velocity due to the orography could
be the biggest factor in the wind pressure calculation. For this coefficient also
alternative procedures could be found, but in this work a correction according to the
given procedures in the EN 1991-1-4 is applied.
vb,0 is the fundamental value of the basic wind velocity, defined as a characteristic
10 minutes mean wind velocity, irrespective from the wind direction and the season,
on 10m height over the surface, on a terrain of category II. The influence of the
elevation could be included in the value of the fundamental basic wind velocity or a
procedure for its determination could be given in the National Annex. The value of
the basic wind velocity is the element needed to define the national wind map.

3. WIND DATA IN THE REPUBLIC OF MACEDONIA

The latest available data for the design wind velocity in the Republic of
Macedonia have been developed by Prof. Dr. met, Petar Gburčik, based on the wind
data for the period from year 1950-1970, for the needs of the Yugoslav Standard YUS
U.C7.110 from year 1991 [1]. According to the National Hydrometeorological
Service in that period have been available climatologically measurements of the wind
velocity, which are not good enough to determine reliable design wind parameters.
The existence of continuous anemometric records at 8 meteorological stations in the
Republic from the year 1980 until today is a sufficient reason and a motive for
determining renewed design wind velocities.
Second reason for developing a more detailed wind map is that 80% of the
territory of Republic of Macedonia has a mountain landscape. Although the territory
is small, the difference between the elevation of 44 m.a.s.l as a lowest point, to 2764

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m.a.s.l as the highest point, and the average elevation for the whole territory of 829
m.a.s.l is remarkable. This causes many non-homogeneous wind characteristics, often
determined with local influences and microclimates. The change of the extreme
values could be really big, even for locations relatively close, therefore it is desirable
to have a zoning of the design velocities in a smaller scale, what is quite difficult.
Data for the maximal monthly 10 minutes mean wind velocities with dominant
direction during that period have been bought from the National Hydrometeorological
Service, for the stations and periods given in Table 1.

Table 1- Available data from continous measurements in the Republic of Macedonia

Months that are
Meteorological station Recorded period
missing
Berovo 1995 – 2009 (180 months) 15
Bitola 1984 – 2009 (312 months) 13
Kriva Palanka 1993 – 2009 (204 months) 3
Lazaropole 1980 – 2009 (360 months) 14
Ohrid 1980 – 2009 (360 months) 0
Prilep 1987 – 2009 (276 months) 1
Skopje 1980 – 2009 (360 months) 0

Although the requests for positioning of the anemometers matches the Eurocode
and the World Meteorological Organization (WMO), the real situation is that the
available measuring stations are mainly in urban areas, on heights different from 10 m
and not on a flat terrain. On the next figures two examples are shown.

Figure 1 - Kriva Palanka, positioning on a Figure 2 - Skopje, positioning on an

hill, in sub-urban area escarpment in suburban terrain with
vegetation, measuring instrument on a top of
a building, on height bigger than 10m

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Before processing the data it is necessary first to verify their quality and to check
for possible errors. Therefore, the following steps are still needed:
 Additional meteorological data (temperature, rain, air pressure) to check the
existence and the type of the meteorological event. This comparison can give a
better overview of the local climate and the existence of mixed climate can be
detected. In case of recorded extreme wind velocities caused from different
meteorological events, they should be identified and analyzed independently one
from another.
 Daily maximal wind gusts, maximal 3 seconds wind velocity, which when
compared can help removing eventually unreal big values or measuring
mistakes.
 The lowest measured wind speed and the duration of the longest calmness in
order to define “the zero” of the instrument and “false calms” to be found.
 Data for the historical positioning of each instrument i.e. changes of the type of
the instrument and its position.

4. REFERENT WIND VELOCITIES IN THE REPUBLIC OF MACEDONIA

After collecting and verifying of the available data, the procedure of obtaining
applicable design wind velocities is to be continued with:
 Correction (normalization) of the data due to the exposure of the measuring
instrument and
 Statistical analyzes of the data.
In the first one listed, the influence of the roughness of the surrounding terrain and
the orography on the measured velocities should be defined. In a complex terrain this
task is a real challenge, because every measuring position is in a specific
environment. Regarding the terrain roughness, in the literature many
recommendations can be found, which are not very different between. Bigger
problem is the influence of the orography, what for additional experimental or
numerical methods are needed, which from the other side cannot guarantee maximal
fidelity in the modeling of a volume in а bigger scale. On some station, as Skopje for
example, further correction for the possible impact on the data from the building on
which the anemometer is placed is needed. All this gives us right to talk about smaller
or bigger accuracy of the data, but not for an exact modeling of the reality.
For estimation of the terrain roughness the data from CORINE (Coordination of
information on the environment) were used, a data base for the land usage and land
coverage, represented in a resolution of 100m x 100m and deployed in 44 classes.
Around every measuring position, this classes were compared with the public satellite
pictures of the earth surface available on-line (e.g. https://maps.google.com) and than
assigned to one of the five terrain cattegories defined in the Eurocode. For estimation
of the orography for each location, the free data from the international project
“Shuttle Radar Topography Mission” (SRTM) led by the american organisations
National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and

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Space Administration (NASA) were used. Processing of the terrain data was done
with the help of the sofware ArcGIS.
The directions of the wind are divided in 8 sectors and for each of them the
particular roughness coefficient and the orography coefficient, following the
recomendations of the EN 1991-1-4, were defined. With this coeffitients the
measured extreme wind velocities in each sector were corrected and normalised to
wind velocities in a flat terrain of cattegory II.
The seasonal factor and directional factor are taken with the value 1,0, since
dividing the data in sectors or periods will need additional information from the
Hydrometeorologycal Service in order to keep the desired number of annual data in
each sector or period. For the design of permanent structures in praxis this
coefficients are not a crucial point.
With regard to the wind statistics there are still different opinions and world-wide
experts do not agree about one standardised method for analysis of the wind climate,
beside the fact that the design wind velocity is one of the central and important points
for standardisation of the wind loads. This debate is influenced by the different
mechanisams of wind creation, specific local conditions on every measuring station
and the permanent developing of the methods for extreme value analysis. The
procedure generally adopted in structural design is based on the cumulative Gumbel
Type I distribution fitted to observed data of the annual maxima of the mean wind
velocity. The disadvantage of this approach lies in the fact that there is no an
asymptote at the tail. The prediction of rare wind velocities is more believable if an
upper limit is included. A trial involving actual weather data indicated a positive
curvature of the distributions and accordingly an upper limit, but also shows that this
issue is not important, as long as the exceedance probability considered is not less
than 0,02. However, the difference becomes larger if extrapolation to smaller
exceedance rates is required.
For the needs of this work, the software ProGumbel based on the generalized
Gumbel method was applied (www.vgb.org/news_pro_gumbel). Generally, the
method fullfills the first theorem of the extreme value theory, which implies that the
maximum of the sample of independent and equaly distributed random variables
converges to one of the three possible distributions with curvature τ<0, τ>0 or τ=0.
Based on the theoretical model and from the available data, the upper part of the
distribution with any curvature, what allows extrapolation of the requested rare
events, can be estimated.
Basic concept of the procedure is the probability method to find the fundamental
three parameters of the Generalized Gumbel distribution: mean value m, standard
deviation σ and the curvature coefficient τ. Those parameteres may be assessed from
the parent sample using the Method of Moments or the Maximum Likelihood
Estimation. Bias-corrections for each parameter, based on the Monte Carlo
simulations, are implemented in the ProGumbel software. More details about the
calculation procedure may be found in [3].

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Using the estimated distribution parameters one can graphically interpolate the
curve of the probability of non-exceedance, Figure 3. From this graph values of the
wind velocity with any requested probability of non-excedance can be read, what can
be used either for temporary structures or for the structures with higher importance.

Figure 3 – GUI of the software ProGumbel Figure 4 – Estimated wind velocities at the 8
with probability of non-exceeding annual meteorological stations derived from a
maxima of the wind velocity at the weather normalized data with the coefficients cr and
station in Skopje co

The Figure 4 shows the this way estimated wind velocities with probability of non-
exceedance of the annual maxima of 0,02 for the mentioned 8 meteorological
stations. This results are valid only for those particular locations and for their specific
surrounding. This values are a bit higher than those in the JUS norm, but comparable
with the velocities provided in the National Annexes of the neighbouring countries.

REFERENCES
[1] Bojović, Aleksandar. 1993. Opterećenje vetrom građevinskih konstrukcija.
Beograd: Građevinska knjiga
[2] Davenport, A.G. 1961. “The application of statistical concepts to the wind
loading of structures”. Proc. Inst. Civil Eng. 19: 449–471
[3] Diburg, S. Hölscher, N. Niemann, H-J. Rosenhauer, W. 2008. Optimierung des
extremwertstatistischen Auswerteverfahrens Gumbel (Optimisation of the
statistical analysis of extreme values based on Gumbel’s distributions).
Ergebnisbericht zum Momentenverfahren. Forschungs- und
Entwicklungsvorhaben des VGB-Sonderausschusses "Anlagentechnik" (SA
"AT" 27/07.) Bochum and Rösrath
[4] EUROCODE 1: Actions on structures - Part 1 – 4: General actions – Wind
actions German version EN 1991-1-4: 2005 + A1: 2010 + AC: 2010
[5] Krey, T. Paul, J. 2014. „Einfluss veschidener Parameter auf dem Böenstaudruck
qp gemäß den Nationalen Anhängen zur EN 1991-1-4“. Band 89, Fachteil der
Windtechnologischen Gesellschaft e.V.

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 SCIENTIFIC CONFERENCE
PLANNING, DESIGN, CONSTRUCITON
AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
Sonja ČEREPNALKOVSKA

CONSTRUCTION PRODUCTS REGULATION (CPR 305/2011),

HARMONIZED STANDARD AND THEIR IMPLEMENTATION
ON A NATIONAL LEVEL
Abstract: The European parliament and the Council on 9 March 2011 adopted REGULATION No
305/2011-CPR, laying down harmonized conditions for the marketing of construction products and
repealing Council Directive 89/106 EEC-CPD. The Regulative 305/2011 applied from 1 July 2013.
Construction products which have been placed on the market in accordance with Council Directive
89/106 EEC-CPD before 1 July 2013 shall be deemed to comply with Regulation.
The author would like to point , that the use of the harmonized standards, and referring to them, is the
easiest and simplest method to guarantee product conformity with the basic requests of the relevant
directive/regulative. It is recommended to producers to apply the harmonized standards, although they
are not mandatory.

Кey words: regulation, construction products, AVCP, CE marking, DoP

UREDBA O GRAĐEVINSKIM PROIZVODIMA (CPR 305/2011)

USAGLAŠENI STANDARDI I NJIHOVA PRIMENA NA
NACIONALOM NIVOU
Rezime: Evropski parlament i Savet usvojili su 9. marta 2011. godine Uredbu o graĎevinskim
proizvodima CPR 305/2011, koja se odnosi na harmonizovane uslove na tržištu graĎevinskih proizvoda i
koja je zamenila Direktivu 89/106 EEC-CPD. Uredba 305/2011 je stupila na snagu 1. jula 2013. godine.
Smatra se da su graĎevinski proizvodi koji su plasirani na tržište prema Direktivi 89/106 EEC-CPD pre
1. jula 2013. godine u skladu sa Uredbom.
Autor bi želeo da istakne da upotreba harmonizovanih standarda predstavlja najlakši i najjednostavniji
način da se garantuje usaglašenost proizvoda sa osnovnim zahtevima relevantne direktive / uredbe.
ProizvoĎačima se preporučuje da primene harmonizovane standarde, iako nisu obavezujući.

Ključne reči: regulativa, graĎevinski proizvodi, sistem procene i verifikacije konstantnosti

karakteristika, CE oznaka, DoP.

M.Sc. Standardization Institute of the Republic of Macedonia - ISRM,Skopje, Republic of Macedonia;

e-mail:cerepnalkovska.sonja@isrm.gov.mk

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1. INTRODUCTION
The construction as a complex commercial field incorporates services and
processes (from projecting to carrying out – executing), like incorporation of ready
for use products, which final result is a product that in every aspect should satisfies
the projected quality, security, as well as the demands of the final user. Strategically,
the construction is one of the most important commercial areas because it provides
construction works and infrastructure for all other commercial and social areas. The
development of the EU legislative in the construction area is a permanent process,
and the instruments for executing the quality policy in this area are very complicated
and in certain since different from the others. The elimination of the technical barriers
in the trade, in the field of construction products has as an objective increasing of the
free movement of the construction products thorough the EU internal market.
The existence of unequal treatment in the market of construction products in the
EU, and the need to establish of equal treatment, the Declaration of performance DoP
and the principle of the system of Assesment and Verification of Constancy of
Perormance_AVCP , were the main reasons for the adoption of the new Regulation
305/2011 - Construction Products Regulation_CPR.

2. WHAT DOES THE NEW REGULATION CONTAINS, I.E THE NEW

NATIONAL LAW ON CONSTRUCTION PRODUCTS
The rules of this Regulation directly affect the conditions for the construction
products. This conditions gradually reflect on the national standards for products,
national technical assessment and technical specifications that are related with the
construction products. This regulations do not apply only to the security of the
buildings and the construction works, but also the health, durability, energy efficient
and protection of the environment.
The new regulation refers to construction product is any product or ‘kit’ which is
produced and placed on the market for incorporation in a permanent manner in
construction works or parts thereof and the performance of which has an effect on the
performance of the construction works with respect to the basic requirements for
construction works (BRWC) (Official Journal of EU,2011). Permanent incorporation
means that the extraction of the product from the object would demanish it's security,
and the removal of the product would be a construction process.
The economy operators are defined as manufacturers, importers, distributers or
authorized representatives. Having this in mind it is clear that the importers have
defined responsibility for the products that they trade. If this is not respected, the
action leads to violation of the Regulation.
The Regulation will settle the systems and the documents for Assessment and
verification of consistency of performance -AVCP. Further on, the Regulation will
settle the actions within the assessment and verification of the consistency of the
properties of the construction products that the construction product producers

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implement as well as the use of the 'CE' mark. Different construction products
influence differently on the safety of the building. The importance of the product is
evaluated according to the consequences that an unsuitable product would have on the
construction. Taking into account the importance of the product in relation to its
essential characteristics there are five different levels of systems of assessment and
verification of constancy of performance (AVCP), which have been defined using the
numbers 1+, 1, 2+, 3, and 4. (Table 1.)
The "System 1+" is the most demanding and is designed for the products which
have the most influence on fulfillment of essential requirements which contribute to
the mechanical resistance and stability and/or fire resistance of works. The System 4
is the least demanding and is designed for products with minor influence on health
and safety.
The harmonized European technical specifications for products provide uniform
methods for assessing and validating the performances in relation to the essential
characteristics of construction products. The performance levels which are required
by the building regulations in Member States, enable construction works to satisfy the
basic requirements for construction works, these are: mechanical resistance and
stability, safety in case of fire, hygiene, health and environment, safety and
accessibility in use, protection against noise, energy economy and heat retention,
sustainable use of natural resources.
Further on, with the Law are regulated the principles for preparation and adopting
of the European Assesment Document – EAD and its contents. This applys to all the
construction products thata are not covered or it is not covered compleatly with the
harmonized standard and in which the properties of its essential caracteristics can not
be fully assesed by the harmonized standard. In that case, on request of the
manufacturer, the Technical Assesment Body – TAB prepares and issues European
Assesment Document – EAD. Further on based on the European Assesment
Document – EAD, on request of the manufacturer, is issued European Technical
Assesment – ETA by the Technica Assessment Body, established in accordance with
the procedures laid down in the provisions of this Regulation. The most relevant
aspect of the regulation relates to the liability of economic operators when placing a
construction product on the market. By issuing and signing of the declaration of
performance economic operator assumes responsibility for the compliance of the
construction product with declared performances. This is a major change compared to
the requirement of old Directive on construction products stating that the
manufacturer has to declare the conformity with the technical specification.
Information that must be declared are listed in harmonized standard or in the relevant
chapter of the European Assessment Document (EAD). The manufacturer has also to
provide the information about the content of dangerous substances in the construction
product. This information has to be provided together with the declaration of
performance.

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3. IMPLEMENTATION ON A NATIONAL LEVEL

The process of harmonization of the national technical legislation with the
European is shown on picture 1, and it is based on the transposing of the European
directives of the New approach of technical conformity and the Global approach for
the conformity assessment.
The directives represent the European legislation that can not be directly applied,
the member states have to transpose in their national legislation.
The directives based on the basic principle of the New and the Global approach,
cover a large group of products and types of risk and determine only the basic
requirements that the products have to fulfil.

EUROPEAN LEVEL NATIONAL LEVEL

New and Global National technical

approach Directives legislation Transposing
Official Journal Directives

Harmonization National standards - Accepted the

european standards harmonized European standards -
CEN/CENELEC/ETSI National body for standardization
Official Journal Official Journal

The application of harmonization european

standards is the basic presumption for the
conformity of the product with the relevant
directive!

Figure 1: Present the process of technical harmonization

The difference between the standards and the legislation (regulative) toward their
appliance, procedure of their compliancy and the participants in their establishing is
given in the table that follows:
Opis Standard Regulativa

primena Dobrovoljna obavezna

način primene Konsenzus većina u zakonodavnom telu
učesnici postupka sve zainteresovane strane zakonodavac
primer ISO, EN, SRB, МКС zakon, pravilnik

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European regulation is directly applicable in Member States. Developing countries

need to transpose into a law. Nevertheless, it is necessary to regulate certain areas at
the national level and those are:
 Publication of national standards which adopt a European harmonized standards for
construction products,
 Determination of the language in which the manufacturer shall draw up a
declaration of performance as well as instructions and safety information,
 Nomination of the competent authority for notification and laying down the
procedure for designation and notification of AVCP bodies,
 Nomination of the competent authority responsible for surveillance of construction
products on the market, delegation of powers to inspectors and penalty provisions,
 Nomination of the competent authority to carry out tasks of the national contact
point for construction products,
 Appointment of Technical Assessment Body (TAB), to which the manufacturer can
apply for obtaining a European Technical Assessment for his innovative product. (It
applies to Member States)

4. HARMONIZED STANDARDS IN THE AREA OF DOORS AND

WINDOWS
Harmonized standards (hEN) are European standards established by the European
standardization organizations (ESO) under the mandate of the European Commission
and/or European Free Trade Association (EFTA). All stakeholders are involved in the
process of developing harmonized standards through European standardization
organizations. ESO shall ensure that the various categories of stakeholders are in all
instances represented in a fair and equitable manner. Harmonized standards shall
provide the methods and the criteria for assessing the performance of construction
products in relation to their essential characteristics.
The Commission shall publish in the Official Journal of the European Union the
list of references of harmonized standards which are in conformity with the relevant
mandates.
The harmonized standards in the area of doors, windows, hardware and garage
doors are prepared in the European Technical Committee „CEN TC 033 Doors,
windows, shutters,building hardware and curtain walling“.
What is in common for all the examples of harmonized standards is that they all
speak of the essential requirements that the products should meet, and that applies to
the characteristics, the conformity and product labeling assessment.
The main harmonized standard in this area is the standard:
МКС EN 14351-1+A1:2011

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EN 14351-1:2006+A1:2010
Windows and doors - Product standard, performance characteristics - Part 1:
Windows and external pedestrian doorsets without resistance to fire and/or smoke
leakage characteristics
This European Standard identifies material independent performance
characteristics that are applicable to windows (including roof windows, roof windows
with external fire resistance and French windows), external pedestrian door sets
(including unframed glass door sets, escape route door sets) and screens.
This European Standard applies to:
 Manually or power operated windows, French windows and screens for
installation in vertical wall apertures and roof windows for installation in
inclined roofs, complete with:
 related hardware, if any;
 weather stripping, if any;
 glazed apertures when intended to have glazed apertures;
 with or without incorporated shutters and/or shutter boxes and/or blinds;
and manually or power operated windows, roof windows, French windows and
screens that are
 fully or partially glazed including any non-transparent infill;
 fixed or partly fixed or open able with one or more casements/sashes (e.g.
hinged, projecting, pivoted, sliding).
 Manually or power operated external pedestrian door sets with flush or paneled
leaves, complete with:
 integral fanlights, if any;
 adjacent parts that are contained within a single frame for inclusion in a single
aperture, if any.

Figure 2: Impact resistance

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The performance characteristics for windows and external pedestrian door sets are
determined and expressed in 24 different of the properties window and set outside
doors. In Table 2 shows which are mandatory in accordance with the Annex „ZA1“ of
the standard.
Table 2: Table of mandatory properties

W = windowa, D = doors, RW = roof windows

Y = mandatory properties; N = no mandatory properties
а = glazed doors with injury risk only
b = threshold levels have been identified by the technical specification writers
c = locked doors in escape routes only

Other standards to windows and doors, not included in 305/2011:

EN 16034:2014
Pedestrian door sets, industrial, commercial, garage doors and openable windows
- Product standard, performance characteristics - Fire resisting and/or smoke
control characteristics
prEN 14351-2
Windows and doors - Product standard, performance characteristics - Part 2:
Internal pedestrian doorsets without resistance to fire and/or smoke leakage
characteristics
МКС EN 14600:2011
EN 14600:2005
Door sets and openable windows with fire resisting and/or smoke control
characteristics - Requirements and classification
Harmonized standard in connection to windows and doors:
МКС EN 13830:2006
EN 13830:2003
Curtain walling - Product standard

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5. CONCLUSION
In the view of the above, the author want to point , that the use of the harmonized
standards, and referring to them, is the easiest and simplest method to guarantee
product conformity with the basic requests of the relevant directive/regulative. It is
recommended to producers to apply the harmonized standards, although they are not
mandatory.
So, the producer can choose whether to apply the harmonized standards or not. If
the producer decides not to use the harmonized standards, he is obliged to prove that
his product conforms to the essential requirements of the relevant directive. If the
producer uses just part of the harmonized standard, or if the applicable harmonized
standard does not cover all the essential requirements, the producer must guarantee
conformity to all of the essential requirements in some other way. In those cases,
calling strictly upon the harmonized standard does not ensure the presumption of
conformity.
The developing countries should create an environment for successful integration
of their economy within the European and the international economy streams, and
that is only possible with the harmonization of the national legislation with the
European and adoption of the European standards as national. That should be result of
the joint efforts of the state bodies, the economy,, the academic society, the experts
and various associations, with the purpose of securing the development of the state
economy and the standard of living.
The quality movement in the world represent a part of the commitment of the
world and European business in the line of adjustment to the changes of the global
market. It is always underlined hot the quality becomes the fundamental way of doing
every business anywhere in the world.

6. REFERENCE
[1] Official Journal of the European Union (4.4.2011). Regulation (EU) No
305/2011 of European Parlament and of the Council of 9 March 2011
[2] BSI (December 2012). Guidance Note on the Construction Products Regulation
[3] EU Commission (September 2002). Guidance Paper B, The definition of Factory
Production Control in Technical Specification for Construction products.
[4] EU Commission (27 May 2004). Guidance Paper D, CE Marking under the
Construction Products Directive.
[5] EU Commission (4 May 2005). Guidance Paper M, Comformity Assessment
under CPD: Initial type-testing and Factory production control.
[6] Aldis Simarcs, Latvian Association of Energy Efficiency

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 SCIENTIFIC CONFERENCE
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AND BUILDING RENEWAL
iNDiS 2015
NOVI SAD, 25-27 NOVEMBER 2015

UDK: 69.05:006.77(4-672EU)
1
Igor DŢOLEV
Meri CVETKOVSKA2
Đorđe LAĐINOVIĆ3
Vlastimir RADONJANIN4
Andrija RAŠETA5

THERMAL ANALYSIS OF CONCRETE MEMBERS SUBJECTED TO

FIRE ACCORDING TO EN 1991-1-2 & EN 1992-1-2
Abstract: To determine the structural behaviour under fire conditions, it is necessary to determine the
temperature field inside the elements for the complete duration of the fire. Heat transfer within the cross-
section affects the physical and mechanical properties of materials which comprise it and, indirectly, the
stress-strain distribution in the elements. In this paper, methodology of advanced heat transfer calculation
according to European norms EN 1991-1-2 and EN 1992-1-2 is presented. An example of the
calculations is illustrated using software packages MIDAS NFX and ANSYS Workbench, and
comparison is made with results presented in Eurocode.

Кey words: heat transfer, conduction, convection, radiation, FEM analysis, fire.
.

TERMIČKA ANALIZA BETONSKIH ELEMENATA IZLOŽENIH

POŽARNIM DEJSTVIMA PREMA EN 1991-1-2 & EN 1992-1-2
Rezime: Za određivanje ponašanja konstrukcije u uslovima poţara, neophodno je odrediti temperaturno
polje unutar elemenata za celokupan period trajanja poţara. Prenos toplote unutar preseka utiče na
fizičko-mehaničke karakteristike materijala koji ga sačinjavaju, a posredno i na naponsko-deformacijsko
stanje elemenata. U radu je predstavljena metodologija naprednog termičkog proračuna prema evropskim
normama EN 1991-1-2 i EN 1992-1-2. Primer proračuna ilustrovan je korišćenjem programskih paketa
MIDAS NFX i ANSYS Workbench, a poređenje je izvršeno sa rezultatima datim u Evrokodu.

Ključne reči: prenos toplote, kondukcija, konvekcija, radijacija, MKE analiza, poţar.

1
MSc, Faculty of Technical Sciences, Novi Sad, Serbia, idzolev@uns.ac.rs
2
PhD, Faculty of Civil Engineering, Skopje, Republic of Macedonia, cvetkovska@gf.ukim.edu.mk
3
PhD, Faculty of Technical Sciences, University of Novi Sad, Republic of Serbia, ladjin@uns.ac.rs
4
PhD, Faculty of Technical Sciences, University of Novi Sad, Republic of Serbia, radonv@uns.ac.rs
5
PhD, Faculty of Technical Sciences, University of Novi Sad, Republic of Serbia, araseta@uns.ac.rs

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1. INTRODUCTION
According to EN 1991-1-2 [1], structural fire analysis should consider defining the
relevant fire scenario, which would determine the corresponding design fire as an
external heat load for the calculation of temperature evolution within the structural
members. Thermal analysis is followed by the calculation of mechanical behaviour of
the structure. Design fire can be represented in a simpler form as a nominal
(monotonically increasing), or parametric temperature-time curve (based on the
physical parameters of the fire sector), with assumed uniform temperature distribution
throughout the compartment, or as a more complex multizone model, and also as a
CFD (computational fluid dynamic) model, giving the temperature evolution in a time
and space dependent manner.
Temperature field in the elements during fire exposure depends on the design fire
model, as well as on the thermal and physical properties of materials they are
comprised of. Due to high termal gradients, in addition to conduction and convection,
radiation should also be considered, as well as the fact that the material properties are
temperature dependent, which makes the problem solving nonlinear.
As the closed form of the governing partial differential heat transfer equation
(PDE) does not exist, a numerical method using Finite Element Analysis [2] has been
widely in use. In the following analyses, Finite Element Method (FEM) software
packages MIDAS NFX [3] and ANSYS Workbench [4] were used to obtain the
temperature fields of the analyzed elements, exposed to the standard ISO 834 fire
curve [5].

2. MODEL PRESENTATION
Heat transfer during fire exposure involves time, which requires transient heat
transfer analysis. Thermal solution of the heat transfer PDE is transformed to the
system of algebraic equations, leading to the following expression:
C T    K T   Q (1)
Where:
C  - is the capacitance matrix,
 K  - is the conductance matrix,
T  - is the temperature field vector,
T  - is the temperature field vector derivative over time,
Q - is the load vector.
To obtain a temperature field within the elements, thermal properties of materials
have to be assessed, based on experimental testings. Reliability of calculation models

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is primarily affected by thermal properties, both at ambient and elevated

temperatures, such as: thermal conductivity (λ), specific heat (cp) and density (ρ).
2.1. Material properties
Determination of these parameters in concrete is not simple, because there are
many other influences that are difficult to separate, such as changes in the chemical
composition of concrete, porosity, absorption of latent heat. As the appropriate
thermal conditions result in physical and chemical changes of concrete, thermal
properties aslo depend on heating rate and history [6].
Thermal conductivity of concrete depends on chemical composition, thermal
conductivity of ingredients and their proportions, moisture content and type of
aggregate and cement. [7] It is mainly influenced by the type of aggregate (which
makes 60-80% of concrete volume) and the moisture content in the element, since the
conductivity of water, although very low, is multiple times higher than the
conductivity of air. According to EN 1992-1-2 [8], thermal conductivity of normal
weight concrete is defined by upper and lower limit values (Fig. 1). The upper limit
has been derived from tests of steel-concrete composite structural elements [9], while
the lower limit matches concretes made with siliceous aggregate.

Figure 1 – Thermal conductivity according to EN 1992-1-2

Specific heat of concrete is mainly influenced by the moisture content, density and
type of aggregate. At ambient temperatures, specific heat of concrete is in the range
500-1130 J/kg°C, depending on the type of aggregate. [6] It is very sensitive to the
physical-chemical transformations in concrete at elevated temperatures with the
vapourisation of free water at about 100°C, recognized by the EN 1992-1-2 (Fig. 2).
Due to chemical reactions that lead to evaporation of water, concrete with initial
moisture experiences weight loss at elevated temperatures. Physical-chemical
transformations include water dilation up to about 80°C, loss of free and physically
bonded water at temperatures between 100°C and 200°C, accompanied by the loss of

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chemically bonded water at temperatures higher than 100°C. Weight loss is mainly
influenced by the type of aggregate. At temperatures higher than 600°C, concretes
made with calcareous aggregate experience much larger weight loss, due to chemical
decomposition of dolomite, than concretes made with siliceous aggregate. [10]
However, according to EN 1992-1-2, weight loss of concrete is not influenced by the
type of aggregate (Fig. 3).

Figure 2 – Specific heat according to EN 1992-1-2

Figure 3 – Density of normal weight concrete (NWC) according to EN 1992-1-2

2.2. Fire load

The most simple way of introducing a fire load is by using nominal fire curves,
which are presented as monotonically increasing functions of one variable (time),
constant throughout a fire sector at each time step. The most frequently used is
ISO 834 fire curve, presented in Fig. 4.

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Figure 4 – Standard nominal ISO 834 fire curve [5]

3. ANALYSIS RESULTS AND DISCUSSION

FEM software packages MIDAS NFX 2014 and ANSYS 16.0 Workbench were
used to obtain temperature fields of analyzed elements, exposed to the standard
ISO 834 fire curve. A transient heat transfer analysis was conducted, adopting the
time step according to recommendations given in [2]. To avoid the appearance of
space oscillations of the solution, in the case of thermal shock, an upper and lower
limit values of time step are determined, resulting in a time step ∆t = 15 s for the
adopted mesh element size ∆x = 0.5 cm.
Conduction, convection and radiation are cosidered according to EN 1991-1-2.
Annex A of the EN 1992-1-2 provides temperature profiles for beams and
columns exposed to ISO 834 fire from all sides, on which the verification of analyses
results is based. Results from the analyses conducted using software MIDAS NFX
and ANSYS Workbench are presented in Fig. 5 and Fig. 6, respectively.

R60 R90 R120

Figure 5 – Temperature profiles after 60, 90 and 120 minutes,
according to EN 1992-1-2 (left) and MIDAS NFX (right)

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R60 R90 R120

Figure 6 – Temperature profiles after 60, 90 and 120 minutes,
according to EN 1992-1-2 (left) and ANSYS Workbench (right)

It can be concluded, that both softwares provide valid results for transient heat
transfer analysis, as given in EN 1992-1-2. Advantage of FEM softwares, regardless
of the numerical approximation of the calculation, is the ability to perform the
analysis on any arbitrary geometry and for any type of external heat load.
Reinforced concrete (RC) frame structure is analyzed, subjected to standard
ISO 834 fire curve in the lower storey. RC plates that divide the frame in horizontal
plane contribute to the rectangular beam converting it to the T-section with effective
width of 170 cm. Due to symmetry along two planes, only 1/4 of the structure is
analyzed and the FE model is presented in Fig. 7.

a) model geometry b) FE model c) details

Figure 7 – Geometry and FE model of analyzed frame structure in ANSYS Workbench

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For the standard fire exposure, EN 1992-1-2 prescribes 3 criteria that members
shall comply with: insulation (I), integrity (E) and mechanical resistance (R). For the
last criterion, additional structural analysis is requried, which is not the subject of this
paper. Integrity is the ability of element to prevent the passage of flames and hot
gasses through it on the unexposed side [1], while the insulation criterion is assumed
to be satisfied if the average temperature rise over the whole of the non-exposed
surface is limited to 140°C, and the maximum temperature rise at any point of that
surface does not exceed 180°C. [8] Temperature distribution at the upper surface of
the T-section is given in Fig. 8.

Figure 8 – Temperature-time distribution on unexposed concrete surface

The insulation criterion for the analyzed frame structure is satisfied for the period
of 3h:36min.

4. CONCLUSION
Fire analysis of structural members consists of heat transfer analysis for the whole
duration of fire and structural analysis which would take into account degradation of
mechanical properties of materials at elevated temperatures. In this paper, the first
part of the analysis is discussed. A numerical approach using FEM softwares MIDAS
NFX and ANSYS Workbench provides a powerfull tool in determining the
temperature distribution within the elements, based on temperature-dependant thermal
properties of materials and considering heat transfer due to conduction, convection
and radiation. It can be concluded that both softwares provide valid temperature
profiles based on the Annex A of EN 1992-1-2, after which a more complex model
was developed and subjected to heat load.
A conclusion based on heat transfer analysis can adress the insulation criteria,
while the integrity and mechanical resistance of the entire structure need to be asessed
using structural analysis, in which direction further research will lead.

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ACKNOWLEDGEMENT
This paper has been done within the scientific research project "Development and
application of contemporary procedures for design, construction and maintenance of
buildings", developed at the Department of Civil Engineering and Geodesy, Faculty of
Technical Sciences, University of Novi Sad.

REFERENCES
[1] EN 1991-1-2 (2002): Actions on Structures, General Actions, Actions on
Structures Exposed to Fire, Brussels, European Committee for Standardization
[2] Bergheau J.-M., Fortunier R. (2008): Finite Element Simulation of Heat
Transfer, Hoboken (NJ), John Wiley & Sons, Inc.
[3] Midas IT (2014): AnalysisManual midas NFX, Gyeonggi, Midas IT
[4] ANSYS® Academic Teaching Mechanical (2015): ANSYS Help Documentation,
Release 16.0, Canonsburg (PA), ANSYS, Inc.
[5] ISO 834 (1975): Fire Resistance Test - Elements of Building Construction.
International Standard 834
[6] Baţant Z.P., Kaplan M.F. (1996): Concrete at High Temperatures, Material
Properties and Mathematical Models, Longman Group Limited
[7] Wang Y., Burgess I., Wald F., Gillie M. (2013): Performance-Based Fire
Engineering of Structures, Taylor & Francis Group
[8] EN 1992-1-1 (2004): Design of Concrete Structures, General Rules and Rules
for Buildings, European Committee for Standardization
[9] EN 1994-1-2 (2003): Design of Composite Steel and Concrete Structures,
General Rules, Structural Fire Design, European Committee for Standardization
[10] Kodur V. (2014): Properties of Concrete at Elevated Temperatures, ISRN Civil
Engineering, Article ID 468510, http://dx.doi.org/10.1155/2014/468510, pp. 1-
15

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ɆȿȭɍɇȺɊɈȾɇȺ ɋȺɊȺȾȵȺ

ɉɨɞɪɲɤɚ ɦɟɻɭɧɚɪɨɞɧoj ɫɚɪɚɞʃɢ ɢɧɫɬɢɬɭɰɢʁɚ ɢɡ Ⱥɉ ȼɨʁɜɨɞɢɧɟ ɭ ɰɢʂɭ ʃɢɯɨɜɨɝ

ɲɬɨ ɡɧɚɱɚʁɧɢʁɟɝ ɭɤʂɭɱɢɜɚʃɚ ɭ ɦɟɻɭɧɚɪɨɞɧɟ ɩɪɨʁɟɤɬɟ ɢ ɩɪɨɝɪɚɦɟ, ɤɚɨ ɢ ʃɢɯɨɜɟ ɚɮɢɪɦɚɰɢʁɟ
ɭ ɦɟɻɭɧɚɪɨɞɧɢɦ ɨɤɜɢɪɢɦɚ, ɩɪɟɞɫɬɚɜʂɚ ʁɟɞɧɭ ɨɞ ɩɪɢɨɪɢɬɟɬɧɢɯ ɚɤɬɢɜɧɨɫɬɢ ɉɨɤɪɚʁɢɧɫɤɨɝ
ɫɟɤɪɟɬɚɪɢʁɚɬɚ ɡɚ ɧɚɭɤɭ ɢ ɬɟɯɧɨɥɨɲɤɢ ɪɚɡɜɨʁ.
Ɇɟɻɭɧɚɪɨɞɧɢ ɚɫɩɟɤɬ ɩɪɨɠɢɦɚ ɫɤɨɪɨ ɫɜɟ ɚɤɬɢɜɧɨɫɬɢ ɋɟɤɪɟɬɚɪɢʁɚɬɚ. ȳɨɲ 2005.
ɝɨɞɢɧɟ ɡɚɩɨɱɟɬɨ ʁɟ ɤɨɦɩɥɟɬɧɨ ɮɢɧɚɧɫɢɪɚʃɟ ɬɡɜ. ɦɟɻɭɪɟɝɢɨɧɚɥɧɢɯ ɩɪɨʁɟɤɚɬɚ ɫɚ ɫɭɫɟɞɧɢɦ
ɡɟɦʂɚɦɚ ɢ ɢɧɫɬɢɬɭɰɢʁɚɦɚ ɢɡ ɬɢɯ ɡɟɦɚʂɚ. ɍɫɥɨɜ ɡɚ ɨɜɟ ɩɪɨʁɟɤɬɟ ɛɢɨ ʁɟ ɞɚ ɫɟ ɮɨɪɦɢɪɚʁɭ
ɡɚʁɟɞɧɢɱɤɢ ɬɢɦɨɜɢ ɢɧɨɫɬɪɚɧɢɯ ɢ ɞɨɦɚʄɢɯ ɩɚɪɬɧɟɪɚ ɢ ɞɚ ɫɟ ɮɨɪɦɚɥɢɡɭʁɟ ʃɢɯɨɜɚ ɫɚɪɚɞʃɚ.
ɉɪɨɰɟɧɚ ɞɚ ʄɟ ɬɨ ɛɢɬɢ ɧɚʁɞɢɪɟɤɬɧɢʁɚ ɩɪɢɩɪɟɦɚ ɬɟɦɚ ɢ ɩɚɪɬɧɟɪɚ ɡɚ ɛɭɞɭʄɟ ɩɪɨʁɟɤɬɟ,
ɩɨɤɚɡɚɥɚ ɫɟ ɤɚɨ ɬɚɱɧɚ. ɇɚɭɱɧɟ ɢɧɬɫɬɢɬɭɰɢʁɟ ɢɡ Ⱥɉ ȼɨʁɜɨɞɢɧɟ ɫɭ ɭ 2014. ɝɨɞɢɧɢ, ɩɭɬɟɦ
ɨɜɢɯ ɩɪɨʁɟɤɚɬɚ, ɭɫɩɨɫɬɚɜɢɥɟ ɫɚɪɚɞʃɭ ɫɚ 109 ɧɚɭɱɧɨɢɫɬɪɚɠɢɜɚɱɤɢɯ ɢɧɫɬɢɬɭɰɢʁɚ ɢɡ 25
ɡɟɦɚʂɚ. ɇɚʁɢɧɬɟɧɡɢɜɧɢʁɚ ɫɚɪɚɞʃɚ ʁɟ ɫɚ ɢɧɫɬɢɬɭɰɢʁɚɦɚ ɢɡ ɡɟɦɚʂɚ ɪɟɝɢɨɧɚ: Ɇɚɻɚɪɫɤɨɦ,
Ɋɭɦɭɧɢʁɨɦ, Ȼɭɝɚɪɫɤɨɦ, ɋɥɨɜɟɧɢʁɨɦ, Ȼɨɫɧɨɦ ɢ ɏɟɪɰɟɝɨɜɢɧɨɦ, ɏɪɜɚɬɫɤɨɦ ɢ ɎȳɊ
Ɇɚɤɟɞɨɧɢʁɨɦ. Ɉɫɢɦ ɡɟɦɚʂɚ ɢɡ ɪɟɝɢɨɧɚ, ɭɫɩɨɫɬɚɜʂɟɧɚ ʁɟ ɢ ɢɡɭɡɟɬɧɨ ɡɧɚɱɚʁɧɚ ɫɚɪɚɞʃɚ ɢ ɫɚ
ɢɧɫɬɢɬɭɰɢʁɚɦɚ ɢɡ: ɇɟɦɚɱɤɟ, ɂɬɚɥɢʁɟ, Ⱥɭɫɬɪɢʁɟ, ȼɟɥɢɤɟ Ȼɪɢɬɚɧɢʁɟ, Ɏɢɧɫɤɟ, Ɏɪɚɧɰɭɫɤɟ,
ɒɜɚʁɰɚɪɫɤɟ, ɒɜɟɞɫɤɟ, ɒɩɚɧɢʁɟ, ɉɨɪɬɭɝɚɥɢʁɟ, Ƚɪɱɤɟ, ɋɥɨɜɚɱɤɟ, Ɋɭɫɢʁɟ, ɑɟɲɤɟ, ɚɥɢ ɢ ɫɚ
ɢɧɫɬɢɬɭɰɢʁɚɦɚ ɢɡ ɞɪɭɝɢɯ ɡɟɦɚʂɚ, ɢ ɬɨ ɢɡ ɋʁɟɞɢʃɟɧɢɯ Ⱥɦɟɪɢɱɤɢɯ ɞɪɠɚɜɚ, Ʉɚɧɚɞɟ, ɂɧɞɢʁɟ ɢ
ɍɤɪɚʁɢɧɟ.
Ɋɟɡɭɥɬɚɬɢ ɢɫɬɪɚɠɢɜɚʃɚ, ɧɚʁɱɟɲʄɟ ɫɚ ɬɢɯ ɩɪɨʁɟɤɚɬɚ, ɩɪɟɡɟɧɬɨɜɚɧɢ ɫɭ ɭ 2014.
ɝɨɞɢɧɢ, ɧɚ ɧɚɭɱɧɨ-ɫɬɪɭɱɧɢɦ ɫɤɭɩɨɜɢɦɚ ɭ 43 ɡɟɦʂɟ ɫɜɟɬɚ. ɍ ɫɜɢɦ ɫɚɨɩɲɬɟɧɢɦ ɪɚɞɨɜɢɦɚ
ɩɨɫɟɛɧɨ ʁɟ ɢɫɬɚɤɧɭɬɨ ɞɚ ʁɟ ɢɫɬɪɚɠɢɜɚʃɟ ɫɭɮɢɧɚɧɫɢɪɚɨ ɉɨɤɪɚʁɢɧɫɤɢ ɫɟɤɪɟɬɚɪɢʁɚɬ ɡɚ ɧɚɭɤɭ
ɢ ɬɟɯɧɨɥɨɲɤɢ ɪɚɡɜɨʁ.
ɍ ɫɭɮɢɧɚɧɫɢɪʃɭ ɨɪɝɚɧɢɡɨɜɚʃɚ ɧɚɭɱɧɨ-ɫɬɪɭɱɧɢɯ ɫɤɭɩɨɜɚ ɭ ɡɟɦʂɢ ɩɨ ɩɪɚɜɢɥɭ ʁɟ
ɧɟɨɩɯɨɞɧɨ ɭɱɟɲʄɟ ɢ ɧɚɭɱɧɢɤɚ ɢɡ ɢɧɨɫɬɪɚɧɫɬɜɚ. ɋɟɤɪɟɬɚɪɢʁɚɬ ʁɟ ɭ 2014. ɝɨɞɢɧɢ
ɫɭɮɢɧɚɧɫɢɪɚɨ ɨɪɝɚɧɢɡɚɰɢʁɭ 66 ɬɚɤɜɚ ɫɤɭɩɚ.
ɂɡɭɡɟɬɧɨ ɜɟɥɢɤɚ ɩɚɠʃɚ ɩɨɤɥɚʃɚ ɫɟ ɢ ɩɨɞɪɲɰɢ ɧɚɭɱɧɨ-ɫɬɪɭɱɧɨɝ ɭɫɚɜɪɲɚɜɚʃɚ
ɢɫɬɪɚɠɢɜɚɱɚ ɭ ɢɧɨɫɬɪɚɧɫɬɜɭ, ɚɥɢ ɢ ɭɫɚɜɪɲɚɜɚʃɭ ɧɚɭɱɧɨɝ ɩɨɞɦɥɚɬɤɚ ɢ ɫɬɭɞɟɧɚɬɚ.
ɋɟɤɪɟɬɚɪɢʁɚɬ ʁɟ ɨɞɨɛɪɢɨ ɢ ɫɪɟɞɫɬɜɚ ɡɚ ɫɭɮɢɧɚɧɫɢɪɚʃɟ ʁɟɞɧɨɝɨɞɢɲʃɟɝ ɛɨɪɚɜɤɚ 8 ɫɬɭɞɟɧɚɬɚ
ɭ ɢɧɨɫɬɪɚɧɫɬɜɭ ɩɨ ɩɪɨʁɟɤɬɭ "Campus Europae".
ɇɚʁɞɢɪɟɤɬɧɢʁɚ ɩɨɞɪɲɤɚ ɋɟɤɪɟɬɚɪɢʁɚɬɚ ɦɟɻɭɧɚɪɨɞɧɨʁ ɢ ɦɟɻɭɪɟɝɢɨɧɚɥɧɨʁ ɫɚɪɚɞʃɢ
ɨɞɜɢʁɚ ɫɟ ɩɭɬɟɦ ɫɭɮɢɧɚɧɫɢɪɚʃɚ ɬɟɤɭʄɢɯ ɚɤɬɢɜɧɨɫɬɢ ɦɟɻɭɧɚɪɨɞɧɟ ɫɚɪɚɞʃɟ ɢɧɫɬɢɬɭɰɢʁɚ ɢɡ
Ⱥɉ ȼɨʁɜɨɞɢɧɟ. Ɉɜɚ ɩɨɞɪɲɤɚ ɡɚɩɨɱɟɬɚ ʁɟ 2005. ɝɨɞɢɧɟ, ɤɚɞɚ ʁɟ ɫɭɮɢɧɚɧɫɢɪɚɧɨ 45
ɚɤɬɢɜɧɨɫɬɢ, ɚ ɭ 2014. ɝɨɞɢɧɢ ɫɭɮɢɧɚɧɫɢɪɚɧɚ ʁɟ ɱɚɤ 191 ɚɤɬɢɜɧɨɫɬ, ɨɞ ɱɟɝɚ ʁɟ 123 ɧɚɫɬɚɜɚɤɚ,
ɢ 68 ɧɨɜɢɯ ɩɪɨʁɟɤɬɚ.
ɂɧɫɬɢɬɭɰɢʁɟ ɫɚ ɞɟɜɟɬ ɮɚɤɭɥɬɟɬɚ ɍɧɢɜɟɪɡɢɬɟɬɚ ɭ ɇɨɜɨɦ ɋɚɞɭ, ɂɫɬɪɚɠɢɜɚɱɤɨ-
ɪɚɡɜɨʁɧɨɝ ɢɧɫɬɢɬɭɬɚ ɡɚ ɧɢɡɢʁɫɤɨ ɲɭɦɚɪɫɬɜɨ ɢ ɠɢɜɨɬɧɭ ɫɪɟɞɢɧɭ, ɇɚɭɱɧɨɝ ɢɧɫɬɢɬɭɬɚ ɡɚ
ɩɪɟɯɪɚɦɛɟɧɟ ɬɟɯɧɨɥɨɝɢʁɟ, ɇɚɭɱɧɨɝ ɢɧɫɬɢɬɭɬɚ ɡɚ ɜɟɬɟɪɢɧɚɪɫɬɜɨ, ɂɧɫɬɢɬɭɬɚ ɡɚ ɪɚɬɚɪɫɬɜɨ ɢ
ɩɨɜɪɬɚɪɫɬɜɨ, ɂɧɫɬɢɬɭɬɚ ɡɚ ɨɧɤɨɥɨɝɢʁɭ ȼɨʁɜɨɞɢɧɟ, Ɏɚɤɭɥɬɟɬa ɡɚ ɫɩɨɪɬ ɢ ɬɭɪɢɡɚɦ
ɍɧɢɜɟɪɡɢɬɟɬɚ ȿɞɭɤɨɧɫ, ȼɢɫɨɤe ɲɤɨɥe ɫɬɪɭɤɨɜɧɢɯ ɫɬɭɞɢʁɚ ɡɚ ɜɚɫɩɢɬɚɱɟ "Ɇɢɯɚʁɥɨ ɉɚɥɨɜ ɭ
ȼɪɲɰɭ, Ⱥɤɚɞɟɦɢʁɟ ɧɚɭɤɚ, ɤɭɥɬɭɪɚ ɢ ɭɦɟɬɧɨɫɬɢ ȼɨʁɜɨɞɢɧɟ, ɤɚɨ ɢ ɫɚɦɨɝ ɍɧɢɜɟɪɡɢɬɟɬɚ ɭ
ɇɨɜɨɦ ɋɚɞɭ ɭɤʂɭɱɟɧɨ ʁɟ ɭ ɧɚʁɜɚɠɧɢʁɟ ɟɜɪɨɩɫɤɟ ɢ ɫɜɟɬɫɤɟ ɩɪɨɝɪɚɦɟ ɢɡ ɨɛɥɚɫɬɢ ɧɚɭɤɟ ɢ
ɞɟɥɨɦ ɨɛɪɚɡɨɜɚʃɚ. ɍ ɨɞɨɛɪɟɧɟ ɩɪɨʁɟɤɬɟ ɭɤʂɭɱɟɧɨ ʁɟ ɜɢɲɟ ɨɞ 45, ɭɝɥɚɜɧɨɦ ɟɜɪɨɩɫɤɢɯ
ɡɟɦɚʂɚ, ɚ ɩɨʁɟɞɢɧɢ ɩɪɨʁɟɤɬɢ ɫɟ ɪɚɞɟ ɭ ɫɚɪɚɞʃɢ ɫɚ ɜɢɲɟ ɨɞ ɞɟɫɟɬ ɡɟɦɚʂɚ. ɉɪɨʁɟɤɬɢ ɫɟ ɪɚɞɟ ɭ
ɫɚɪɚɞʃɢ ɫɚ 951 ɢɧɫɬɢɬɭɰɢʁɨɦ ɢɡ ɢɧɨɫɬɪɚɧɫɬɜɚ
 Ɉɤɜɢɪɧɢ ɩɪɨɝɪɚɦ ɡɚ ɢɫɬɪɚɠɢɜɚʃɚ ɢ ɪɚɡɜɨʁ ȿɜɪɨɩɫɤɟ ɭɧɢʁɟ (FP), ɤɚɨ ɝɥɚɜɧɢ
ɢɧɫɬɪɭɦɟɧɬ ɡɚ ɫɩɪɨɜɨɻɟʃɟ ɧɚɭɱɧɨɢɫɬɪɚɠɢɜɚɱɤɟ ɩɨɥɢɬɢɤɟ ɭ ȿɜɪɨɩɫɤɨʁ ɭɧɢʁɢ, ɤɨʁɢ
ɩɪɟɞɫɬɚɜʂɚ ɬɪɟʄɢ ɩɨ ɜɟɥɢɱɢɧɢ ɨɩɟɪɚɬɢɜɧɢ ɛɭʇɟɬ ɭ ɨɤɜɢɪɭ ɭɤɭɩɧɨɝ ɛɭʇɟɬɚ ȿɍ (ɩɨɫɥɟ
ɡɚʁɟɞɧɢɱɤɟ ɩɨʂɨɩɪɢɜɪɟɞɧɟ ɩɨɥɢɬɢɤɟ ɢ ɪɟɝɢɨɧɚɥɧɟ ɩɨɥɢɬɢɤɟ). Ɉɞ 2005. ɞɨ 2009. ɝɨɞɢɧɟ
ɩɨɞɪɠɚɧɨ ʁɟ ɭɤɭɩɧɨ 29 ɩɪɨʁɟɤɚɬɚ ɢɡ FP5 ɢ FP6 ɉɪɨɝɪɚɦɚ, ɚ 2014 ɝɨɞɢɧɟ ɢ 17 ɧɨɜɢɯ
ɩɪɨʁɟɤɬɚ ɢɡ FP7 ɉɪɨɝɪɚɦɚ.
Ɂɧɚɱɚʁɧɚ ɩɨɞɪɲɤɚ ʁɟ ɞɚɬɚ ɢ ɭɱɟɲʄɭ ɭ TEMPUS ɩɪɨɝɪɚɦɭ, ɤɨʁɢ ɢɦɚ ɡɚ ɰɢʂ ɞɚ ɫɟ
ɤɪɨɡ ɡɚʁɟɞɧɢɱɤɭ ɫɚɪɚɞʃɭ ɡɟɦɚʂɚ ȿɍ ɢ ɂɫɬɨɱɧɟ ɢ ɐɟɧɬɪɚɥɧɟ ȿɜɪɨɩɟ ɩɨɦɨɝɧɟ ɬɢɦ ɡɟɦʂɚɦɚ
ɞɚ ɪɟɮɨɪɦɢɲɭ ɢ ɭɧɚɩɪɟɞɟ ɫɜɨʁɟ ɫɢɫɬɟɦɟ ɜɢɫɨɤɨɝ ɨɛɪɚɡɨɜɚʃɚ ɭ ɫɤɥɨɩɭ ɲɢɪɢɯ ɟɤɨɧɨɦɫɤɢɯ ɢ
ɞɪɭɲɬɜɟɧɢɯ ɪɟɮɨɪɦɢ. ɍ 2014. ɝɨɞɢɧɢ ɋɟɤɪɟɬɚɪɢʁɚɬ ʁɟ ɫɭɮɢɧɚɧɫɢɪɚɨ 23 TEMPUS ɩɪɨʁɟɤɬɚ
ɧɚɲɢɯ ɧɚɭɱɧɨɢɫɬɪɚɠɢɜɚɱɤɢɯ ɢɧɫɬɢɬɭɰɢʁɚ.
ɍɤɭɩɧɨ 27 ɩɪɨʁɟɤɚɬɚ ʁɟ ɫɭɮɢɧɚɧɫɢɪɚɧɨ ɭ 2014. ɝɨɞɢɧɢ ɢɡ CEEPUS ɩɪɨɝɪɚɦɚ ɡɚ
ɪɚɡɦɟɧɭ ɫɬɭɞɟɧɚɬɚ ɢ ɩɪɨɮɟɫɨɪɚ. Ɉɜɚʁ ɩɪɨɝɪɚɦ ɢɦɚ ɡɚ ɰɢʂ ɭɫɩɨɫɬɚɜʂɚʃɟ ɦɭɥɬɢɥɚɬɟɪɚɥɧɟ
ɞɢɦɟɧɡɢʁɟ ɤɪɨɡ ɚɤɚɞɟɦɫɤɭ ɦɨɛɢɥɧɨɫɬ ɭɧɭɬɚɪ ɫɪɟɞʃɨɟɜɪɨɩɫɤɨɝ ɢ ʁɭɠɧɨɟɜɪɨɩɫɤɨɝ ɪɟɝɢɨɧɚ ɢ
ɩɪɨɦɨɜɢɫɚʃɟ ɰɟɥɨɤɭɩɧɢɯ ɩɪɨɝɪɚɦɚ ɢ ɦɪɟɠɚ, ɧɚɪɨɱɢɬɨ ɦɪɟɠɚ ɡɚʁɟɞɧɢɱɤɢɯ ɞɢɩɥɨɦɚ, ɤɚɨ ɢ
ɭɫɩɨɫɬɚɜʂɚʃɟ ȿɜɪɨɩɫɤɨɝ ɜɢɫɨɤɨɨɛɪɚɡɨɜɧɨɝ ɩɪɨɫɬɨɪɚ.
ɋ ɨɛɡɢɪɨɦ ɧɚ ɡɧɚɱɚʁ ɩɨɝɪɚɧɢɱɧɟ ɫɚɪɚɞʃɟ ɫɚ ɫɭɫɟɞɧɢɦ ɡɟɦʂɚɦɚ ɩɨɫɟɛɧɚ ɩɚɠʃɚ ɫɟ
ɩɨɤɥɚʃɚ ɢ ɫɭɮɢɧɚɧɫɢɪɚʃɭ IPA ɩɪɨʁɟɤɚɬɚ. ɍ 2014. ɝɨɞɢɧɢ ɫɭɮɢɧɚɧɫɢɪɚɧɨ ʁɟ ɭɤɭɩɧɨ 6
ɩɪɨʁɟɤɬɚ ɢɡ ɬɨɝ ɩɪɨɝɪɚɦɚ.
ɉɨɪɟɞ ɧɚɜɟɞɟɧɢɯ, ɫɭɮɢɧɚɧɫɢɪɚɧɢ ɫɭ ɢ ɩɪɨʁɟɤɬɢ ɢɡ COST, EUREKA, DAAD,
SCOPES, US-EPA, SEE Transnational Cooperation Progremme, NATO Science for Peace and
Security Programme, Stability pact ɩɪɨɝɪɚɦɚ, ɤɚɨ ɢ ɦɭɥɬɢɥɚɬɟɪɚɥɧɟ ɢ ɛɢɥɚɬɟɪɚɥɧɟ
ɚɤɬɢɜɧɨɫɬɢ ɧɚɭɱɧɨɢɫɬɪɚɠɢɜɚɱɤɢɯ ɢɧɫɬɢɬɭɰɢʁɚ ɢɡ ȼɨʁɜɨɞɢɧɟ.
Ʉɚɤɨ ɛɢ ɫɟ ʁɨɲ ɜɢɲɟ ɩɨɞɫɬɚɤɥɨ ɭɤʂɭɱɢɜɚʃɟ ɧɚɲɢɯ ɢɧɫɬɢɬɭɰɢʁɚ ɭ ȿɜɪɨɩɫɤɢ
ɢɫɬɪɚɠɢɜɚɱɤɢ ɩɪɨɫɬɨɪ ɢ ɩɨɞɧɨɲɟʃɟ ɧɨɜɢɯ ɩɪɢʁɚɜɚ ɡɚ ɦɟɻɭɧɚɪɨɞɧɟ ɩɪɨʁɟɤɬɟ ɋɟɤɪɟɬɚɪɢʁɚɬ
ʁɟ ɢ ɭ 2014. ɝɨɞɢɧɢ ɧɚɫɬaɜɢɨ ɫɚ ɮɢɧɚɧɫɢʁɫɤɨɦ ɩɨɞɪɲɤɨɦ ɩɪɢʁɚɜɟ ɦɟɻɭɧɚɪɨɞɧɢɯ ɩɪɨʁɟɤɚɬɚ
ɩɨ ɩɪɨɝɪɚɦɢɦɚ ȿɜɪɨɩɫɤɟ ɭɧɢʁɟ, ɩɪɢ ɱɟɦɭ ɫɭ ɩɪɢɨɪɢɬɟɬ ɢɦɚɥɟ ɩɪɢʁɚɜɟ ɡɚ ɩɪɨɝɪɚɦ
ɏɨɪɢɡɨɧɬ 2020 . ɋɪɟɞɫɬɜɚ ɫɟ ɨɞɨɛɪɚɜɚʁɭ ɡɚ ɬɟɯɧɢɱɤɭ ɩɪɢɩɪɟɦɭ ɢ ɩɨɬɪɟɛɧɟ ɤɨɧɬɚɤɬɟ ɡɚ
ɪɟɚɥɢɡɚɰɢʁɭ ɩɪɢʁɚɜɟ ɦɟɻɭɧɚɪɨɞɧɢɯ ɩɪɨʁɟɤɚɬɚ.
ɋ ɨɛɡɢɪɨɦ ɧɚ ɬɨ ɞɚ ɫɭ ɰɢʂɟɜɢ ȿɜɪɨɩɫɤɟ ɭɧɢʁɟ ɫɬɜɚɪɚʃɟ ʁɟɞɢɧɫɬɜɟɧɨɝ ȿɜɪɨɩɫɤɨɝ
ɢɫɬɪɚɠɢɜɚɱɤɨɝ ɩɪɨɫɬɨɪɚ ɢ ɪɚɡɜɨʁ ɤɨɧɤɭɪɟɧɬɧɨɝ ɞɪɭɲɬɜɚ ɛɚɡɢɪɚɧɨɝ ɧɚ ɡɧɚʃɭ, ɤɚɨ ɢ ɧɚ
ɫɬɪɚɬɟɲɤɨ ɨɩɪɟɞɟʂɟʃɟ ɧɚɲɟ ɡɟɦʂɟ ɡɚ ɩɪɢɤʂɭɱɢɜɚʃɟ ȿɍ ɭ ɲɬɨ ɫɤɨɪɢʁɟɦ ɩɟɪɢɨɞɭ,
ɩɨɞɪɲɤɚ ɦɟɻɭɧɚɪɨɞɧɨʁ ɫɚɪɚɞʃɢ ɨɫɬɚʁɟ ɭ ɜɪɯɭ ɚɝɟɧɞɟ ɪɚɞɚ ɉɨɤɪɚʁɢɧɫɤɨɝ ɫɟɤɪɟɬɚɪɢʁɚɬɚ ɡɚ
ɧɚɭɤɭ ɢ ɬɟɯɧɨɥɨɲɤɢ ɪɚɡɜɨʁ ɢ ɭ ɧɚɪɟɞɧɨɦ ɩɟɪɢɨɞɭ.

Ⱦɪɚɝɢɰɚ Ʉɨɥʇɢɧ, ɫɚɦɨɫɬɚɥɧɢ ɫɬɪɭɱɧɢ ɫɪɚɞɧɢɤ ɡɚ ɦɟɻɭɪɟɝɢɨɧɚɥɧɭ ɢ ɦɟɻɭɧɚɪɨɞɧɭ ɫɚɪɚɞʃɭ.

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ʣ˃ˍ˖ˎ˕ˈ˕ ˕ˈ˘ːˋ˚ˍˋ˘ ː˃˖ˍ˃ǡ ˑ˔ːˑ˅˃ː ͳͻ͸ͲǤ Š‡ ƒ…—Ž–› ‘ˆ ‡…Š‹…ƒŽ …‹‡…‡•ǡ ™Š‹…Š ™ƒ• ‡•Ǧ
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͵Ǥ ʒ˓˃˥ˈ˅ˋː˔ˍˑˋːˉˈ˰ˈ˓˔˕˅ˑ ͵Ǥ ‹˜‹Ž‡‰‹‡‡”‹‰
ͶǤ ʠ˃ˑ˄˓˃˱˃ˬːˑˋːˉˈ˰ˈ˓˔˕˅ˑ ͶǤ ”ƒˆϐ‹…‡‰‹‡‡”‹‰
ͷǤ ʏ˓˘ˋ˕ˈˍ˕˖˓˃ ͷǤ ”…Š‹–‡…–—”‡
͸Ǥ ʗːˇ˖˔˕˓ˋˬ˔ˍˑˋːˉˈ˰ˈ˓˔˕˅ˑˋˋːˉˈ˰ˈ˓˔ˍˋ ͸Ǥ †—•–”‹ƒŽ‡‰‹‡‡”‹‰ƒ†
ˏˈː˃˳ˏˈː˕ ‡‰‹‡‡”‹‰ƒƒ‰‡‡–
͹Ǥ ʗːˉˈ˰ˈ˓˔˕˅ˑˊ˃˛˕ˋ˕ˈˉˋ˅ˑ˕ːˈ˔˓ˈˇˋːˈˋ ͹Ǥ ˜‹”‘‡–ƒŽ‡‰‹‡‡”‹‰ƒ†
ˊ˃˛˕ˋ˕ˈː˃˓˃ˇ˖ ‘……—’ƒ–‹‘ƒŽ•ƒˆ‡–›‡‰‹‡‡”‹‰
ͺǤ ʒˈˑˇˈ˕˔ˍˑˋːˉˈ˰ˈ˓˔˕˅ˑ ͺǤ
‡‘†‡•›

ʗː˕ˈ˓ˇˋ˔˙ˋ˒ˎˋː˃˓ːˈ˔˕˖ˇˋˬˈǣ –‡”†‹•…‹’Ž‹ƒ”›•–—†‹‡•ǣ
ͳǤ ʒ˓˃˗ˋ˚ˍˑˋːˉˈ˰ˈ˓˔˕˅ˑˋˇˋˊ˃ˬː ͳǤ
”ƒ’Š‹…‡‰‹‡‡”‹‰ƒ††‡•‹‰
ʹǤ ʛˈ˘˃˕˓ˑːˋˍ˃ ʹǤ ‡…Šƒ–”‘‹…•
͵Ǥ ʢ˒˓˃˅˯˃˰ˈ˓ˋˊˋˍˑˏˑˇˍ˃˕˃˔˕˓ˑ˗˃ˎːˋ˘ ͵Ǥ ‹•ƒ•–‡”‹•ƒƒ‰‡‡–ƒ†
ˇˑˆ˃˥˃ˬ˃ˋ˒ˑˉ˃˓˃  ‹”‡ƒˆ‡–›
ͶǤ ʞ˓ˋˏˈ˰ˈː˃ˏ˃˕ˈˏ˃˕ˋˍ˃ ͶǤ ’’Ž‹‡†ƒ–Š‡ƒ–‹…•
ͷǤ ʟ˃˚˖ː˃˓˔ˍ˃ˆ˓˃˗ˋˍ˃ ͷǤ ‘’—–‡”‰”ƒ’Š‹…•
͸Ǥ ʔːˈ˓ˆˈ˕˔ˍ˃ˈ˗ˋˍ˃˔ːˑ˔˕˖ˊˆ˓˃ˇ˃˓˔˕˅˖ ͸Ǥ ‡”‰›ˆϐ‹…‹‡…›‹—‹Ž†‹‰•
͹Ǥ ʠ˙ˈː˔ˍˋˇˋˊ˃ˬː ͹Ǥ …‡‡†‡•‹‰
ͺǤ ʐˋˑˏˈˇˋ˙ˋː˔ˍˑˋːˉˈ˰ˈ˓˔˕˅ˑ ͺǤ ‹‘‡†‹…ƒŽ‡‰‹‡‡”‹‰
ͻǤ ʡˈ˘ːˋ˚ˍ˃ˏˈ˘˃ːˋˍ˃ ͻǤ ‡…Š‹…ƒŽ‡…Šƒ‹…•
ͳͲǤ ʔːˈ˓ˆˈ˕˔ˍˈ˕ˈ˘ːˑˎˑˆˋˬˈ ͳͲǤ ‡”‰›–‡…Š‘Ž‘‰‹‡•
ͳͳǤ ʢ˓˄˃ːˋˊ˃ˏˋ˓ˈˆˋˑː˃ˎːˋ˓˃ˊ˅ˑˬ ͳͳǤ ”„ƒ’Žƒ‹‰ƒ†”‡‰‹‘ƒŽ†‡˜‡Ž‘’‡–
ͳʹǤ ʡ˓ˈ˕ˏ˃ːˋˊ˃˛˕ˋ˕˃˅ˑˇ˃ ͳʹǤ ƒ–‡”–”‡ƒ–‡–ƒ†’”‘–‡…–‹‘‡‰‹‡‡”‹‰
ͳ͵Ǥ ʗːˉˈ˰ˈ˓˔˕˅ˑˋː˗ˑ˓ˏ˃˙ˋˑːˋ˘˔ˋ˔˕ˈˏ˃ ͳ͵Ǥ ˆ‘”ƒ–‹‘›•–‡•‰‹‡‡”‹‰

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 Organizers of Conference

department of
civil engineering
and geodesy

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Аутономна Покрајина Војводина
Покрајински секретаријат за науку и
технолошки развој

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