CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

EUCALYPTUS LIBYA, TRIPOLI

LIBYA
CONCEPT DESIGN REPORT STRUCTURAL
ENGINEERING
XXTH MARCH 2010

Issue/revision

Revision 0

Revision 1

Revision 2

Revision 3

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Remarks
Date
Prepared by
Signature
Checked by
Signature
Authorised by
Signature
Project number
File reference

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

inde

1.

INTRODUCTION
1.1

SCOPE & PROJECT DESCRIPTION

1.2.

DESIGN CODES

1.3.

CONSTRUCTION MATERIALS

1.3.1

Concrete

1.3.2

Steel

1.4.

2.

ANALYSIS AND DESIGN SOFTWARE TOOLS

1.4.1

Design Packages

1.4. 2

CAD Package

1.4.3

Documentation Management System

1.5

Durability And Fire Resistance

1.6

Design Criteria

1.6.1

Serviceability Limit State

1.6.2

Build-ability and Value Engineering

1.6.3

Health and Safety

DESIGN LOADS AND LOADING COMBINATION

2.1

2.2

Proposed Loadings

2.1.1

Material Densities

2.1.2

Dead Loads

2.1.3

Live Loads

Lateral Loads

2.2.1

Seismic Load

2.2.2

Wind Loads

2.3

Earth Pressure Loads

10

2.4

Hydrostatic Loads

10

2.5

Load Combinations

10

2.5.1

Ultimate

10

2.5.2

Working

10

3.

GEOTECHNICAL INTERPRETATIVE REPORT

10

4.

LATERAL SUPPORT /SHORING

10

5.

DEWATERING

11

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

6.

BULK EARTH WORKS

11

7.

WATER PROOFING AND SURFACE PROTECTION SYSTEM

11

8.

SPECIFICATIONS

11

9.

OVERVIEW OF STRUCTURAL STRATEGIES

12

9.1

Summary

12

9.2

Foundations

12

9.3

Ground Slab

12

9.4

Columns And Shear Walls

12

9.5

Slabs And Beams

12

9.6

Expansion Joints

17

9.7

Facade

17

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

INTRODUCTION

1.1

SCOPE & PROJECT DESCRIPTION

The purpose of this report is to conclusively address the issue of structural feasibility by demonstrating overall stability and structural adequacy with respect to the loads such as gravity, wind and seismic, that the structure will have to withstand.
The scope includes the general requirements and various design parameters that are considered in the structural design. The structural design of the building will be carried out with due regard to the following considerations:

Efficient and Cost effective design and sizing of elements,

lEase of Operation and Maintainability of building,

Feel of safety and comfort levels for occupants,

Co-ordination with other disciplines like, Architectural, MEP and Interior Design Departments.

This report addresses two components within the Eucalyptus development, they are campus commercial and the shopping centre.
CAMPUS COMMERCIAL:
The scope includes the design and construction of the campus commercial offices which will act as a connection between gate way buildings, Conference Facility/Exhibition Centre, Hotel, Residential and Commercial zone and the remaining facilities on site. Main scope elements
include;
- Transfer beams will be required at podium level below the buildings due to the change in geometry of the buildings and the discontinuity of the columns at the podium level to upper floors.
-Deep soil fill is required at podium level due to the landscape around the buildings.
SHOPPING CENTRE:
The scope includes the design and construction of the shopping centre which will provide a vital revenue stream and act as a connection between the residential zone and the hotel/conference/exhibition area. It includes a large hypermarket, department store, cinema various
other shops and cafes/restaurants. Specifically, the main scope elements include;
- A glazed panelled roof skylight over Food court/Retail area at 4th floor.
- A large cantilever portion at one of the corners which is supported by raking columns.

1.2

DESIGN CODES

Concrete
BS8110: Part 1: 1985

(Amended November 2005) Part 1: Code

of practice for design and construction

BS8110: Part 2: 1985

British Standard: Structural use of concrete

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

(Amended November 2005)

Part 2: Code

Of practice for special circumstances

Structural Steelwork
BS5950: Part 1: 2000

British Standard: Structural use of Steelwork in building

(Amended May 2001) Part 1: Code of practice for design
Of rolled and welded sections

BS5950: Part 2: 2001

British Standard: Structural use of steelwork in building

Part 2: Specifications for materials, fabrication and erection:

BS5950: Part 3:

rolled and welded sections.

British Standard: Structural use of steelwork in building

Sections 3.1: 1990 Part 3: Design in composite construction
(Amended October 2006)Section 3.1: Code of practice for design of simple and continuous composite beams)

BS5950: Part 4: 1994

British Standard: Structural use of steelwork in building

Part 4: Code of practice for design of composite slabs with

BS5950: Part 8: 2003

profiled steel sheeting

British Standard: Structural use of steelwork in building

Part 8: Code of Practice for the resistant design

Foundations
BS8004: 1986

British Standard: Code of practice for foundations

BS8102: 1990

British Standard: Code of practice for protection of structures

BS648: 1964

British Standard of weights of building materials

against water from the ground

Loadings
(Amended October 1969)
BS6399: Part 1:1996

British Standard: Loading for buildings

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

(Amended October 2002) Part 1: Code of Practice

For dead and imposed loads
BS6399: Part 3: 1988

British Standard: Loadings for Buildings

(Amended May 1997) Part3: code of Practice for
Imposed Roof Loads

ASCE 7-02

American Society of Civil Engineers: Loading for buildings

Minimum Design Loads for Buildings and Other Structures

UBC 97

Uniform Building Code

Code of Practice for Seismic loads (Earth Quake Loads)

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

1.3

CONSTRUCTION MATERIALS

1.3.1

CONCRETE
The design of all cast in situ concrete elements will be based on the following concrete grades and reinforcement specification.

CONCRETE GRADE
MPa
COMMERCIAL
SHOPPING CENTRE
CAMPUS

ELEMENT
Sub Structure
Foundations
Super Structure
Slabs
Retaining Walls
Columns
Shear Walls, Lift Walls and Staircase Walls
Beams

40

45

40
40
50
50
40

45
45
60
60
45

Concrete mixes shall be designed with durability specifications for sub and super structure in accordance with the Geotechnical Investigation
recommendation.

All site tests shall be carried out by an approved independent third party testing laboratory. The test results
Shall be submitted to the Engineer for review and approval.
The nominal maximum size of aggregate shall be 20mm, unless otherwise approved.
Conventional reinforcement must have yield strength of not less than 360 MPa for mild steel and
460 MPa for high yield tensile reinforcement.(Deformed bars Type 2, conforming to BS 4449:1988)
Welded wire reinforcement to be hard drawn mild steel conforming to BS 4482.

1.3.2

STRUCTURAL STEEL
The particular grade of steel used shall be as follows:

Grade 43 (S275JR/ BS-EN-10025) or Grade 50 (S355JR/ BS-EN-10025) - for Hot rolled sections,
Hollow Sections, Bars and Plates up to 16mm thickness

Grade 43 (S275JR/ BS-EN-10025) - for Base Plates.

Protection against Corrosion will be specified according to requirement, four technical systems for protection
of steel against corrosion will be considered according to the site conditions, international standards, code
of practice and local authority requirements:

Painting

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Galvanising

Spray Metal Coating

Nuts, Bolts and Washers protection.

1.4

ANALYSIS AND DESIGN SOFTWARE TOOLS

1.4.1

DESIGN PACKAGES
The project will be delivered utilizing the following technology packages:
In the analysis of the different structural elements, GAJ is utilizing the following structural software

1.4. 2

Etabs

Sap 2000

Safe

Prokon

Excel design spreadsheets

CAD PACKAGES
All the CAD documentation is prepared using AutoCAD drafting software.

1.4.3

DOCUMENTATION MANAGEMENT SYSTEM

All documentation will be stored on the documentation management system, in accordance with our ISO 9001: 2000 certification.
Data backups are done on a daily basis.

1.5

DURABILITY AND FIRE RESISTANCE

In order to ensure sufficient protection against corrosion and fire the following cover to the reinforcement will be considered in the design of the concrete elements:
Element
Foundation (shallow-deep)
Ground Beams/Retaining wall

Concrete Cover
70mm
50mm

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Columns

30mm

Shear Walls

30mm

Slabs / side cover of beams

30mm

Top and bottom cover of beams

30mm

Steel work shall be protected by such means in tumescent coating; plasterboard; block work; concrete encasement; fire protection spray, as to achieve the required fire resistance. A fire rating of 2 hours will be considered for all concrete structural framing elements.
1.6

DESIGN CRITERIA

1.6.1

SERVICEABILITY LIMIT STATE

FOR GRAVITY LOAD:
Vertical deflection:
Reinforced concrete beams and slabs deflection are based on limiting the total deflection to span/250 and this should normally ensure that the part of the deflection occurring after construction of finishes and partitions will be limited to span/500 or 20mm,
whichever is the lesser, for spans up to 10m.
Vibration Limits:

Target system frequency of 4HZ

FOR SEISMIC LOAD:

The Inelastic Response sway M = 0.7RS

Story Drift Limitation using M shall not exceed 0.025xh for fundamental period less than 0.7 seconds and 0.020xh for fundamental periods equal or greater than 0.7 seconds.(where h is storey height)

FOR WIND LOAD:

1.6.2

Peak lateral drift under serviceability wind load conditions of : Height/500

Maximum inter-storey drift under serviceability wind load conditions of : Height/400

BUILD-ABILITY AND VALUE ENGINEERING

Productivity and quality are two inter-related issues of utmost importance in the construction industry. The build-ability concept and ISO quality management systems are used to help raise productivity and quality standards in construction.
Build-ability is the provision of construction details and materials, which simplify the construction process. Achieving build ability will help reduce construction costs and likelihood of claims.
Following are some of the general principles to be considered in design to achieve good build-ability:

Carry out thorough site investigation prior to design.

Designing for standardisation, repetition, safety and ease of construction.

10

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Selecting a structural system that suits the site conditions.

Minimising the number of different types of components, to simplify the process of sorting on site and make the potential for reprocess more attractive due to the large quantities of same or similar items.

Designing the components, to a size, to suit the intended means of handling i.e., assembly, transport, handling etc.

Plan for essential site production requirements.

Designs should allow for accessibility of labour, materials and plant.

In the design we carry out value engineering study to achieve essential functions at the lowest total costs over the life of the project with the following phases,

1.6.3

Information: Gathering the information about the present design and cost, then determines the needs, requirements and constraints of the owner as well as the design criteria.

Function Analysis: Analyzing the functions to determine which need improvement, elimination or combination.

Creation: Using a variety of creative techniques such as brainstorming, to generate alternative ideas to perform the Project functions.

Evaluation: Refines and combines ideas, develops functional alternatives and evaluates by comparison.

Development: Based on the evaluation phase, the team begins to develop in detail the alternatives with the greatest Potential value. During this phase it is essential to establish costs and backup documentation needed to individually convey the alternative solutions.

Presentation: The final phase of the VE study in which the best alternative will be chosen and presented to the

client for final decision.

HEALTH AND SAFETY

The design will be carried out with due consideration for compliance with health and safety standards and safe methods of construction and maintenance, to reduce the large number of serious and fatal accidents and cases of ill health which
occur in the construction industry.

Buildings will be designed to withstand all foreseeable loadings and operational extremes throughout the life of the building.

Buildings will be designed to sound engineering principles in accordance with appropriate design codes and fit for purpose.

DESIGN LOADS AND LOADING COMBINATION

2.1

PROPOSED LOADINGS
The proposed dead, live and lateral loads for the design of the buildings are set out below.

2.1.1

MATERIAL DENSITIES
The following densities will be used to calculate the dead loads for the various structural elements:

Plain Concrete

22 kN/m3

11

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

2.1.2

Reinforced Concrete

24 kN/m3

Screed

20 kN/m3

Steel

78.5 kN/m3

Dry Soil

18 kN/m3

Saturated Soil

20 kN/m3

Water

10 kN/m3

Hollow Block Work

18 kN/m3

Solid Block Work

22 kN/m3

DEAD LOADS
Public Areas

Finishes

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Finishes

2.0 kN/m2

Ceiling/Services

0.5 kN/m2

Partitions

2.0 kN/m2

Offices

Residential Floors

Finishes

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Partitions

4.0 kN/m2 (For block work partitions)

Screed (thickness50mm)

1.5 kN/m2

Insulation/Waterproofing

0.1 kN/m2

Ceiling/Services

0.5 kN/m2

1.5m Soil landscape

Podium

27.0 kN/m2

Retail areas

12

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Screed (75mm)

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Cinema Area

Screed (75mm)

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Hypermarket/ Departmental Stores

Screed (75mm)

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Storage Area (Cold and General)

Screed (75mm)

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Stairs & Corridors

Screed (75mm)

1.5 kN/m2

Ceiling/Services

0.5 kN/m2

Plant Rooms/Sub Station/ MEP Rooms

Screed (50mm)

1.0 kN/m2

Ceiling/Services

0.5 kN/m2

Roof

2.1.3

1.1 kN/m2

50mm gravel / concrete pavers

Screed (average thickness 150mm) 3.0 kN/m2

Insulation / Waterproofing

0.1 kN/m2

Ceiling/Services

0.5 kN/m2

Line load on perimeter of slab

4.0 kN/m/meter height

LIVE LOADS

Public Areas

5.0 kN/m2

13

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Offices

Retail Areas

Cinema Area

Hypermarket

Residential Floors

2.0 kN/m2

Stairs and Corridors

4.0 kN/m2

Parking Floors

3.5 kN/m2

Drive ways and Ramps

3.5 kN/m2

General Storage

2.4 kN/m2 / meter height

Cold Storage

5.0 kN/m2/ meter height with min. 15kN/m2

Plant Rooms/Substations/MEP Rooms

7.5 kN/m2

Roof with access

2.0 kN/m2

Roof without access

1.0 kN/m2

3.5 kN/m2
5.0 kN/m2
5.0 kN/m2
7.5 kN/m2

2.2

LATERAL LOADS

2.2.1

SEISMIC LOAD
The structures will be designed to UBC 97 seismic zone 2A as per the local Authority Requirements
The zone coefficient taken 0.15 as per UBC97 Table 16-I
Occupancy Category:

4 - Standard Occupancy Structures

Seismic Importance factor I = 1.0

Site Geology and Soil Characteristics:

Soil Profile Type Sd (Assumed)Required conformation from soil investigation

Site Seismic Hazard Characteristics:

Seismic Force Amplification Factor ()=2.8

Ductility Factor R = 5.5

Tension Factor Seismic Zone 2A

14

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

2.2.2

50year Design Life

WIND LOAD
The design will consider the more onerous of the following lateral loading conditions:

Wind

Basic wind speed 45m/s

Ground roughness category 2
Class C

2.3

Notional Horizontal Force :

in accordance with BS8110: Part 1, clause 3.1.4.2

EARTH PRESSURE LOADS

The project has basements, so the external basement wall will be designed for earth pressure loads in addition to the vertical loads.

2.4

HYDROSTATIC PRESSURE LOADS

The project is close to the sea and has basements, as a result a high water table is expected. Depending upon the soil Investigation report recommendations, Foundation system and the retaining walls will be designed for hydrostatic Pressure Loads.

2.5

LOAD COMBINATIONS

2.5.1

ULTIMATE LOAD COMBINATIONS:

1.4D + 1.2T
1.4D + 1.6L + 1.2T
1.2D + 1.2L 1.2Wx + 1.2T
1.2D + 1.2L 1.2Wy + 1.2T
1.4D 1.4Wx + 1.2T
1.4D 1.4Wy + 1.2T
0.9D 1.3Wx + 1.2T
0.9D 1.3Wy + 1.2T
1.32D + 0.55L 1.1Ex + 1.2T
1.32D + 0.55L 1.1Ey + 1.2T
1.32D + 1.1L 1.1Ex + 1.2T
1.32D + 1.1L 1.1Ey + 1.2T
1.0D 1.1Ex + 1.2T
15

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

1.0D 1.1Ey + 1.2T

2.5.2

SERVICE LOAD COMBINATIONS:

1.0D + 1.0T
1.0D + 1.0L + 1.0T
1.0D + 1.0L 1.0Wx + 1.0T
1.0D + 1.0L 1.0Wy + 1.0T
1.0D 1.0Wx + 1.0T
1.0D 1.0Wy + 1.0T
1.0D + 0.75L 1.0Wx + 1.0T
1.0D + 0.75L 1.0Wy + 1.0T
1.0D 0.714Ex + 1.0T
1.0D 0.714Ey + 1.0T
1.0D + 1.0L 0.714Ex + 1.0T
1.0D + 1.0L 0.714Ey + 1.0T
1.0D + 0.75L 0.714Ex + 1.0T
1.0D + 0.75L 0.714Ey + 1.0T

3.

GEOTECHNICAL INTERPRETATIVE REPORT

Due to the knowledge of coastal area we expect to find a layer of Calcarenites and Calcareous Sandstone below the ground level.
A Specification for Soil Investigation has been prepared to carry out the detailed soil investigation to determine the properties of the underlying strata, which will form the basis for establishing an appropriate foundation system
The interpretative report shall include, but not be limited to:
Geotechnical assessment of the ground and groundwater conditions underlying the site
Established engineering parameters of the soil at the site
Assessment of chemical attack potential on buried concrete and reinforcement.
Recommendations on foundation systems including provisional Soil Bearing Capacity, Modulus of Sub grade reaction and safe pile working loads (tensile and compressive).
The site is populated with Eucalyptus trees. Permanent removal of these trees for the construction purpose may raise the ground water table level. Peizometers have been proposed to monitor the ground water table fluctuations through the course of the Geotechnical
investigation and the construction of the project.

4.

LATERAL SUPPORT /SHORING

Shoring system is a structure that is built or put in place to support the sides of an excavation to retain earth, water, and adjacent structures.
A battered excavation with self supported ground cut back to safe slopes can be achieved if there is enough available working space around the site perimeter or a shoring system that supports the sides of an excavation.
16

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Depending upon the depth of excavation and the geotechnical Investigation report recommendations, one of the following suitable and economical lateral support/shoring systems will be adopted

Soldier Piles

Secant piles

Contiguous piles

Diaphragm Wall

The design and installation of the lateral support system will be carried out by a specialist Contractor.

5.

DEWATERING
The Project is close to the Sea and as a result a high water table is expected. Basements are always being constructed for parking and services area below the building which will possibly require dewatering.
Subject to the comments of the geotechnical investigation report, if dewatering is required, that can be carried out by deep well or well point system, which will be based upon the size and depth of the excavation, geological conditions, and characteristics of
the soil.
The design and installation of the dewatering system will be carried out by a specialist Contractor.
Dewatering if required will be maintained until the building has been constructed up to a certain level which will be based on the design to ensure that the building is safely counter-balanced by the dead weight to the uplift caused by
the hydrostatic pressure.

6.

BULK EARTH WORKS.

Following the installation of the lateral support system and the site dewatering system, the bulk
Earth works will be carried out for the basement excavation area by a specialist Contractor.
The excavation will be carried out to the formation level of the foundations which will be engineered to the recommendations of the Soil Investigation Report.
Close co-ordination will be required between the bulk earthworks contractor, the lateral support system contractor and the temporary dewatering contractor to agree programming and phasing of each element of work to be carried out.

7.

WATER PROOFING AND SURFACE PROTECTION SYSTEM

Upon the findings of the geotechnical investigation report, a below ground water proofing system will be selected to best suit the levels of exposure, depth of basement and characteristics of the soil.
The water proofing system will be supplied and installed by a specialist Contractor.

8.

SPECIFICATIONS

17

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

The following specifications will be fully addressed in the later stages of the design development
General Requirements
Quality Standards and Control
Site Requirements
Demolition and Site Clearance
Shoring
Bulk Earth Works
Dewatering
Concrete
Applicable Codes and References
Concrete Materials & Methods
Formwork & Finishes
Joints for In Situ Concrete
Reinforcing Steel
Masonry
Concrete Block work walls
Metals
Structural Steel
Steel Decking
Water Proofing
Water Tank GRP Lining

9.

OVERVIEW OF STRUCTURAL STRATEGIES

9.1

SUMMARY
The scope of work includes the study of the most suitable structural system and to explain the feasibility of the system adopted. This report addresses the different priorities in the design and its approach in the construction activity.
The structure must be designed with an adequate factor of safety, in order to fulfil both strength and stability requirements.
The fundamental objectives of structural design are discussed. The basic system to be adopted for principal building structural elements such as floors, beams, columns and roofs is decided. A structural system is selected upon evaluating a number of possible
options on their performance against a number of criteria, among these are structural strength, cost, speed, quality, build-ability and familiarity.

9.2

FOUNDATIONS

18

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Foundations are the structural concrete elements that transmit the weight of the structure to the supporting soil. Structural foundation system will be decided upon to best suit the project and recommendation of geotechnical investigation report.
Foundation to the super structure and basement structure will be supported at basement formation level.
Very significant Hydrostatic Pressure will arise due to the high water table. This Hydrostatic force will be resisted by the combination of dead weights of the structure.
9.3

GROUND SLAB
The project is close to the sea and as a result a high water table is expected. Ground floor/Foundation slab is being designed for uplift due to the hydrostatic pressure.

9.4

COLUMNS AND SHEAR WALLS

These are the vertical elements which supports the structural floor system. They are compression members subjected in most cases to both bending and axial load and are of major importance in the safety considerations of any structure.
Structural concrete walls are often necessary as elevator/stairwell walls and shear walls that resist horizontal wind and earthquake induced loads.
The main lateral load-resisting system consists of reinforced concrete shear walls .These walls are continuous throughout the building height.
The main gravity load-resisting system consists of reinforced concrete columns and shear walls.

9.5

SLABS AND BEAMS

Among the building structural elements, floor construction is the most time-consuming and costly activity particularly for a framed building, representing some 60%-80% of the total in both cost and time .
In order to achieve the most efficient and economical structural floor system, a total of 8 structural floor systems have been examined and compared by the design team. The structural floor systems considered are listed below:
1. In-situ concrete flat slab
2. In-situ concrete Post tension Slab.
3. In-situ concrete flat slab with drop panel
4. Solid in-situ concrete slab with drop beams
5. Reinforced concrete waffle slab with band beams
6. Reinforced concrete ribbed slab with band beams.
7. Composite steel beam with decking slab
8. Precast Concrete.
These structural floor systems are presented and discussed in more detail below. In ordered to optimize the parking allowance in the basements and to achieve a feasible floor slab system a 9x9 m column grid has been adopted.
All of above structural floor systems are in wide spread use in the building construction industry.

System 1: In-situ Concrete Flat Slab:

Flat slabs are one of the most commonly used structural systems in residential buildings, hotels, and commercial buildings. These are solid concrete slabs of uniform thickness that transfer the load directly to the columns without the presence of projected
beams.

19

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Drop beams may be required at locations where heavy concentrated loads are to be supported and where beam/column framing action is required to enhance lateral stability. Drop beams may also be required to control deflections, in particular where brittle
facade finishes such as glazing are used. To maximize the benefits of this system, the use of drop beams will be kept to a minimum.
Advantages:
Ease and speed of construction, due to simple flat slab soffit which minimizes complexity of shuttering.

Having a shallow structural zone with good flexibility in horizontal distribution of services.

A more flexible layout of partitions can be accommodated.

Disadvantages:
This system needs to pre-plan positions of vertical risers.

Limitations on locating large openings close to columns.

System 2: Post-tension Slab:

Post-tensioned concrete is reinforced with a grid of high-strength sheathed steel tendons, or cables. While the concrete is curing, the cables are tensioned and held permanently under stress by anchoring them. This squeezing action keeps the concrete in
compression, improving its tensile (or bending) strength.

Advantages:
Larger spans are designed with less thickness.

20

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

The post-tensioning force can counteract the self-weight of the slab, resulting in much less dead load deflection. The designer can control the deflections to a much greater extent than with RC slab. However, the larger spans possible with PT can lead to
live load deflection issues.

Disadvantages:
It requires much more skilled Contractor than RC slab. Small errors can have large impacts.

The early stressing of the concrete leads to more shrinkage than would be seen in an RC slab. If restraint is present that resists the shrinkage (e.g. Shear wall), cracks can develop in unexpected places.

Less flexibility in cutting the concrete in future modifications, due to the location of stressed tendons embedded in the concrete.

System 3: In-situ Concrete Flat Slab with Drop Panels:

Flat slabs with drop panels are solid concrete slabs of uniform thickness with slab drops at columns.
Loads are directly transferred to the columns without the presence of projected beams.
Drop beams may be required at locations where heavy concentrated loads are to be supported and where beam/column framing action is required to enhance lateral stability. Drop beams may also be required to control deflections, in particular where brittle
faade finishes such as glazing are used. To maximize the benefits of this system, the use of drop beams will be kept to a minimum.
Advantages:

The system also offers a shallow structural zone

Good flexibility in horizontal distribution of services.

More flexible layout of partitions can be accommodated.

21

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Disadvantages:

This system again needs to pre-plan positions of vertical risers.

Limitations on locating large openings near columns.

There is more complex construction associated with forming the drop panels at each column.

Restricted horizontal service distribution.

System 4: Solid In-situ Concrete Slab with Drop Beams:

Solid slabs are the reinforced concrete slabs supported on deep reinforced down-stand/up stand beams. The slab and beams are cast monolithically. Solid slabs are the commonly used structural system in residential buildings and hotels.
Advantages:
Relatively simple construction which is familiar to local contractors.

The grid of down-stand beams will provide additional framing action throughout the structure.

Disadvantages:
Relatively deep structural zone due to down stand beams which requires a larger floor to floor height.

Restricted full service zone through out due to down stand beams

Formwork is more complex than the flat slab system as described in System 1 due to the down-stand/up stand beams

22

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

System 5: Reinforced Concrete Waffle Slab with Band Beams:

Waffle slab system has a solid topping concrete slab with deep down stand ribs at regular spacing in both directions. The deep structural zone set by the wide beams spanning at 9.0m centres and providing primary support to the two-way spanning waffle
slab.
Advantages:
Lightweight structure due to the reduced volume of concrete.

Longer spans with heavy loads.

Electrical and mechanical installation can be placed between voids.

Easy to make penetrations in the slab for services.

Disadvantages:
Complexity of shuttering makes construction more difficult.

Not familiar to local contractors.

23

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

System 6: Reinforced Concrete Ribbed Slab with Band beams:

Ribbed slab system has a solid topping concrete slab with deep down stand ribs at regular spacing in one direction. The deep structural zone set by the wide beams providing primary support to the one way spanning ribs.
Advantages:
Lightweight structure due to the reduced volume of concrete

Relatively good horizontal distribution of services

Having considerable extra strength on one direction.

Disadvantages:
Complexity of shuttering making construction more difficult.

Not familiar to local contractors.

24

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

System 7: Composite Steel Beam with Decking Slab:

Composite slabs are cast in-situ concrete slab supported over a permanent metal decking which is supported on a steel beam and column structural frame. The deck slab and beams are designed to act compositely so as to minimize the beam depth. The
composite interaction is achieved by the attachment of shear connectors to the top flange of the steel beam.
Advantages:
Light weight construction.

Speed up construction process

Profiled steel sheeting act as a safe working platform and permanent formwork.

Unpropped construction may be achieved

Disadvantages:
A higher floor to floor height is required to allow the services passing under structural zone

The structural steel requires additional fire protection

Susceptible to corrosion due to the local climate.

The steel structure would require bracing on the external facade of the structure which may compromise the open glazed facade system.

A specialist Contractor is required for fabrication and construction.

25

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

System 8: Pre-cast Concrete:

Precast concrete slabs consists of concrete members cast at an offsite precast plant and trucked to the site for installation or cast on site and put in place with mechanical equipments/cranes.
Advantages:

Rapid construction on site.

High quality because of the controlled conditions in the factory.

Less disruption of traffic and site during erection.

Potentially Improved safety with most of fabrication being performed off-site.

Disadvantages:

Precast members are less flexible and adaptable to changes or modifications that can be required on jobsite.

Joints between panels are often expensive and complicated.

Skilled workmanship is required in the application of the panel on site.

Mechanical equipments/Cranes are required to lift panels.

Conclusion:
Upon reviewing the above structural slab systems and to achieve a feasible floor slab system for a 9x9 m column grid, following systems are recommended for the Campus Commercial and the shopping centre:

26

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Campus Commercial:
- Flat slab system for parking floors, Office Floor slab and Roof.
- Waffle slab system for Ground floor slab where there are heavy loads due to landscape soil fill
Down stand beams and column heads will be required at isolated locations, but will be kept to minimum.
Shopping Centre:
- Flat slab system for parking floors, retail areas Supported on reinforced concrete columns and walls set out 9mx9m structural grid. Beams and slab drops will be required at isolated locations, but will be kept to minimum.
- Structural steel roof truss structures will be designed over the cinema area.

9.6

EXPANSION JOINTS
Four expansion joints are being proposed in the commercial block starts from lower Basement to Ground floor with two columns side by side. Two expansion joints are being proposed in the shopping centre throughout the building height with two columns side by side.
Campus Commercial

27

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

Shopping Centre

28

CONCEPT DESIGN REPORT STRUCTURAL ENGINEERING

xxTH MAR 2010

9.7

FACADE
The facade is required to fulfil a wide range of Architectural requirements which includes weather tightness, to resist rain and wind penetration.
As per the Architectural proposal, all the sides of Commercial Complex are covered with glass facade and in the Shopping Centre the front side is covered with glass facade and other sides are covered by Stone Cladding
The structural system for the facade will be designed by specialist Consultant/Contractor.

29