ADVANCED DESIGN OF GLASS
STRUCTURES
Lecture L1
Historical highlights, production and material
characterisation
Viorel Ungureanu
European Erasmus Mundus Master Course
Sustainable Constructions
under Natural Hazards and Catastrophic Events
520121-1-2011-1-CZ-ERA MUNDUS-EMMC
List of lessons
2
Objectives of the lecture
Objectives
Introduction
Introduction to glass structures
Historical review
Production Historical review
Chemical
composition Production - glass products, edge quality
Glass products,
edge quality Material and mechanical properties
Material and
mechanical
properties
Testing of glass elements
Strength of
annealed glass
3
Introduction
Objectives
Transparency in Design
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
EVOLUTION
Material and
mechanical
properties
Strength of
annealed glass
4
Introduction
Objectives
Intention versus Realisation
Introduction
Historical review
Production 20 m
Chemical
composition
Glass products,
1220 m
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Grand Canyon Skywalk USA
cantilever bridge
deck width 3,1m
low iron glass
glass railing 1,57m tall
5
Introduction
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Grand Canyon Skywalk, USA - assembled on top of the canyon wall in line
with its final placement and moved into final position by a jack and roll rig
8 box posts 810 x 810mm, 2 bridge box beams 810 x 1800mm
6
Introduction
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Grand Canyon Skywalk, USA
7
Introduction
Objectives
Introduction
Historical review
Load bearing elements
Production
from glass
Chemical
composition
Purpose
Glass products,
edge quality Architectural aspects of
Material and new structures
mechanical
properties
Design of glass structures
Strength of
annealed glass
8
Historical review
Objectives
Introduction
the oldest finds of glass in Egypt 10 000 BC
Historical review glass recipe, Middle East, 668-626 BC: Take 60 parts of sand, 180
parts of ash from marine plants, 5 parts of chalk and you will obtain
Production
glass
Chemical
composition glass blower's pipe - finding around turn of the era
Glass products, glass blowing to the forms production of the bottles, mugs
edge quality
(hollow objects)
Material and
mechanical 6th century
properties
Strength of
annealed glass
Celtic bracelets
Phoenician glass
9
Historical review
Objectives
Introduction Flat glass
Historical review 10th 11th century first panes for windows
Production until 19th century: crown process
Chemical
composition
glassmaker blew a large bubble of glass which he spun rapidly while
glass was still soft production of disc in diameter 1.5 1.8 m, panes
Glass products,
edge quality up to 0,5 x 0,75m
Material and thinnest glass at the edge of the disk, thicker glass and more opaque
mechanical
properties
toward the center
Strength of
annealed glass
10
Historical review
Objectives
Crown glass was an early type of window glass. In this process, glass
Introduction
was blown into a "crown" or hollow globe. This was then transferred
Historical review
from the blowpipe to a punty (iron rod) and then flattened by reheating
Production and spinning out the bowl-shaped piece of glass (bullion) into a flat
Chemical disk by centrifugal force, up to 1.5 to 1.8 meters in diameter. The glass
composition was then cut to the size required.
Glass products, The thinnest glass was in a band at the edge of the disk, with the glass
edge quality
becoming thicker and more opaque toward the center.
Material and Due to the distribution of the best glass, in order to fill large window
mechanical
properties spaces many small diamond shapes would be cut from the edge of the
disk and these would be mounted into a lead lattice work and fitted in
Strength of
annealed glass the window. Known as a bullseye, the thicker center area around the
punty mark was used for less expensive windows.
11
Historical review
Objectives
Introduction Crown glass
Historical review for large window small diamond
Production shapes cut from the edge mounted
Chemical
into a lead lattice work and fitted in the
composition window
Glass products, thicker center area used for less
edge quality
expensive windows - bullseye
Material and
mechanical St. Jan Ktitel, Osek
properties
around 1360
Strength of
annealed glass
bullseyes
12
Historical review
Objectives
Introduction Flat glass
Historical review cylinder process - broad sheets
Production
blowing a bubble of glass, swinging it into a cylindrical shape, the
Chemical ends of cylinder were cut off, it was slit longitudinally, reheated
composition
and opened out into flat sheet panes up to 1,0 x 1,3m, more
Glass products,
edge quality
uniform thickness
Material and
mechanical
properties
Strength of
annealed glass
glassworks
13
Historical review
Objectives
19. century: invention of Siemens-Martin firing method higher
Introduction
temperature better quality of glass
Historical review
1871 Pilkington machine for automated production: from discontinuous
Production
to flow production
Chemical beginning of the 20th century: development of various drawn flat sheet
composition
processes
Glass products,
edge quality 1) molten glass was drawn from furnace in thin stream, flattened and cooled
Material and by pulling between asbestos rollers
mechanical
properties 2) rolling process: manufacture of patterned flat or wired glass molten
glass was poured between water-cooled rollers
Strength of
annealed glass
Fourcault Pittsburgh Libby-Owens
14
Historical review
Objectives
Palm House in Kew
Introduction
Gardens, UK, 1844
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Chiselhampton, UK,
around 1800
15
Production
Objectives
mid-20th century developed float glass process (Pilkington Brothers 1959)
Introduction
Historical review
Production
Raw materials Melting furnace Float bath Annealing lehr
Chemical
composition
Cutting
Glass products, section
edge quality
Material and
mechanical
properties
1 500
C 1 600
C 1 100
C 600
C 200
C
Strength of
annealed glass
Molten glass Molten tin
silica sand, soda ash, limestone and salt cake with cullet
controlled heating permits glass to flow
flat ribbon of uniform thickness, brilliant and flat parallel surfaces
16
Production
Objectives
Introduction
Float glass
Historical review glass: 2500 kg/m x Sn:
Production 6500 kg/m
Chemical
tin bath
tin (Sn) is liquid from 270 C
composition
to 2270 C
Glass products,
edge quality
Material and equilibrium t = 7mm
mechanical
properties changing speed 0.4mm < t
< 25 mm
Strength of
annealed glass
constant width
17
Production
Objectives
Float glass plant
Introduction
Historical review
Production
Chemical Float glass ribbon cut to
composition
panel size
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
18
Production
Objectives
Introduction
Production of one float
Historical review
line
Production
900 m float glass (4mm) per
hour
Chemical
composition 700 tons per day
Glass products, 70 000 m float glass (4mm)
edge quality
per day
Material and
mechanical 35 full trucks per day
properties
Strength of
annealed glass
19
Chemical composition
Objectives
Introduction
Historical review What is glass ?
Production
Chemical
composition
Glass products,
edge quality Quartz SiO2 (Crystalline)
Material and Silicon dioxide SiO2
mechanical
properties
Strength of Silica Glass (Amorphous)
annealed glass
Soda Lime Silica glass
(Amorphous)
Sodium (Na) used to reduce
the melting temperature
20
Chemical composition
Objectives
Introduction
Glass is isotropic, inorganic, visco-elastic material
Historical review
without lattice structure, solid at room temperature,
liquid above transition zone ~580 C.
Production
Chemical Typical composition:
composition
Silica SiO2 70 74%
Glass products,
edge quality Lime CaO 5 12%
Material and soda Na2O 12 16%
mechanical
properties other chemical elements with influence to: spectral transmittance,
thermal properties, tensile strength, fracture toughness, colour, etc.
Strength of
annealed glass
Glass colours produced by the addition of metal oxides
green iron or chromium oxide
red copper oxide or gold oxide
blue cobalt oxide
21
Chemical composition
Objectives
Soda Lime Borosilicate
Introduction
Silica Glass Glass
Historical review
Silica sand SiO2 69 74 % 70 87 %
Production
Lime CaO 5 14 %
Chemical Soda Na2O 10 16 % 08%
composition
Boron-oxide B2O3 7 15 %
Glass products,
edge quality Magnesia MgO 06%
Material and Alumina Al2O3 03% 08%
mechanical
properties Others - 05% 08%
Strength of Indicatory values (mass %) according to EN 572-1&2
annealed glass
Borosilicate glass:
better resistance against thermal shock
more expensive than Soda Lime Silica Glass
exceptional in construction - e.g. glass tubes,
22
Glass products, edge quality
Objectives
Introduction
Size and tolerances
Historical review Nominal thickness:
Production 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 (and 25*) mm
Chemical
composition Standard sheet size: 6 m x 3.21 m
Glass products,
edge quality
Oversized sheets: possible, though rather exceptional
Material and
mechanical
properties Annealed glass:
Strength of no (significant) residual
annealed glass stresses
Exceptionally large glass
pane, made in China (25 m)
23
Glass products, edge quality
Objectives
Introduction Manufacturing tolerances
Historical review
Dimensional accuracy
Production
length 2 4 mm
Chemical
composition squareness (difference in length between diagonals of a rectangle)
Glass products,
2 4 mm
edge quality thickness of the float glass in the table
Material and diameter of drilled holes 0,5 mm
mechanical
properties distance of the hole's centres 0,5 2 mm
Strength of
annealed glass
nominal thickness [mm] tolerances [mm]
2 - 6 mm 0,2 mm
8 - 12 mm 0,3 mm
15 mm 0,5 mm
19 - 25 mm 1,0 mm
annealed flat glass low initial deformation < L/2500 (negligible)
24
Glass products, edge quality
Objectives
flat glass
Introduction
t = 3, 4, 5, 6, 7, 8, 10, 12, 15, 19, 25 mm,
Historical review
max. size 6,0 x 3,2 m
Production
Chemical
composition
channel glass C, U
length up to 6,0 m
Glass products,
edge quality
Material and circular tube
mechanical thickness from 0,7 to 10,0 mm,
properties
diameters d = 3 to 325 mm low iron channel glass profile
Strength of
annealed glass
glass block
hollow - (115 x 115 x 80 mm - 300 x 300 x 95 mm)
solid - (120 x 120 x 40 mm - 200 x 200 x 50 mm)
curved glass
radius R = 300 mm -
depend on the thickness, bends in one or two planes
25
Glass products, edge quality
Objectives
Introduction Edge quality Edge shape
Historical review
Production
CUT unfinished sides of glass with
sharp edges; cut
Chemical
composition 2 mm
ARRISED the sharp cut edges have 45 2
Glass products, been broken off or bevelled with a
edge quality grinding tool mitre
Material and
mechanical
properties
GROUND to required dimensions,
with blank spots
Strength of
annealed glass bevel (facetted)
FINE GROUND edge is fully ground
over its full surfaces, without blank
spots
POLISHED the fine ground edges round
are finely polished
half-round
26
Edge Finishing
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
J. Belis (UGent), @
Lerobel
computer controlled machine
27
Hole Drilling / Water Jet Cutting
Objectives
Introduction
Historical review
Production
Chemical cylindrical hole
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
conical hole
undercut hole
water cutting
28
Edge Finishing
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
29
Material and mechanical properties
Objectives
Introduction
High durability
Historical review
Production Resistance to:
Chemical
composition water percolation
Glass products,
edge quality
corrosion
Material and
mechanical
properties salt water
Strength of
annealed glass carbonated water
strong acids
organic solvents
ultra-violet radiation
30
Material and mechanical properties
Objectives
Introduction
Glass property Value Unit
Historical review
Production Density 2500 kg/m3
Chemical Young's modulus of elasticity E 70 000 MPa
composition
Glass products, Shear modulus G 30 000 MPa
edge quality
Material and Poisson's ratio 0,23 -
mechanical
properties Coefficient of thermal expansion T 7,7 - 8,8 x 106 1/K
Strength of
annealed glass Thermal conductivity 1,0 W/(mK)
Emissivity 0,89 -
Compressive strength up to 1 000 MPa
Tensile strength 10 - 100 MPa
31
Effect of Temperature on the Viscosity of Glass
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
32
Effect of Temperature on the Viscosity of Glass
Objectives
Introduction
The chemical composition has an important influence on the
viscosity, the melting temperature Ts and the thermal
Historical review
expansion coefficient T of glass.
Production
While the melting temperature is about 1710C for pure
Chemical
composition silica oxide, it drops to 1300 - 1600C through the addition of
Glass products, alkali.
edge quality
The thermal expansion coefficient is about 0,5 10-6K-1 for
Material and
mechanical
pure silica glass and 9 10-6K-1 for soda lime silica glass.
properties During the cooling of the liquid glass, its viscosity increases
Strength of constantly until solidification at about 1014Pa s. The
annealed glass
temperature at solidification is called transition temperature Tg
and is about 530 C for soda lime silica glass.
Melting gradual (Melted glass is like Honey).
33
Material and mechanical properties
Objectives
Stress Stress Stress
Introduction ultimate
strength fu
Historical review
yield
Production strength fy
Chemical
design strength
composition fd
ultimate
strength fk ultimate
Glass products, strength fk
edge quality
design
Material and strength fd design
mechanical strength fd
properties
Strength of Strain Strain Strain
annealed glass elastic elastic plastic elastic plastic
range range range range
range
GLASS STEEL TIMBER
annealed glass behaves perfectly elastically until the moment it fractures
without warning
dangerous shards
no creep, no fatigue in the metallurgical sense
slow growth of cracks under sustained or cyclical loading
34
Mechanical Behaviour
Objectives
Linear elastic behaviour; no plasticity Tension
Introduction
Historical review
Production BRITTLE BEHAVIOUR
max Brittle fracture
Chemical
composition
Glass breaks suddenly
Glass products, Glass breaks completely
edge quality E
Material and
mechanical
properties
Strength of As such, glass is NOT safe as a building material
annealed glass
35
Strength of annealed glass
Objectives
Introduction
Strength of glass depends on:
Historical review
Production
surface condition and edge quality
Chemical load duration
composition
environmental condition, especially humidity
Glass products,
edge quality stress distribution on the surface
Material and
mechanical size of the stressed area
properties
damage of glass surface flaws and cracks
Strength of
annealed glass
36
Strength of annealed glass
Objectives
Introduction
Irregularities and defects in glass
Historical review
Production
manufacturing in material (vents, sulphate scab, inclusions)
Chemical
composition mechanical processing sawing, cutting, drilling, edge and
Glass products, surface grinding
edge quality
environment cleaning (new micro cracks and scratches are
Material and
mechanical generated)
properties
glass has ability to reverse damage in unstressed state (i.e. heal
Strength of
annealed glass the micro cracks)
37
Strength of annealed glass
Objectives
Introduction Relationship between time to failure and applied stress
Historical review
Production
Relative strength
Chemical
composition
2,0
Glass products,
edge quality 1,0
Material and 0,8
mechanical
properties 0,6
Strength of
annealed glass 0,4
10-2 100 102 104 108
1s 1min 1h 1d 1 year
Load duration
Strength of annealed glass is time-depended
38
Strength of annealed glass
Objectives
Introduction Relationship between time to failure and applied
Historical review
stress
Production
Chemical
composition T = cons tan t
n
Glass products,
edge quality - stress
Material and T - duration of stress
mechanical n - constant
properties
Strength of environment constant n
annealed glass
water at 25C recommended for design purposes 16,0
air with 50% relative humidity at 25C 18,1
air with 10% relative humidity at 25C 27,0
vacuum 70,0
melting snow at 2C 16,0
39
Strength of annealed glass
Objectives
Graph of crack growth speed versus stress intensity for
Introduction
different humidities
Historical review
VR
Production [m/sec]
104 1540 m/sec
Chemical
composition
102
Glass products,
edge quality
1
Material and
mechanical
properties 10-2 liquid water - room
temperature
Strength of
annealed glass 10-4
liquid water
temperature 2C
10-6
vacuum
10-8
50% relative
humidity RT K1 [MPa]
10-10
0,1 0,2 0,5 0,8 1 1,5 2
Humidity encourage crack growth
40
Strength of annealed glass
Objectives
Introduction Edge finishing
Historical review
clean cut edge
log (probability of failure)
Production
arrissed edge
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Low risk level
edge strength
41
Strength of annealed glass
Objectives
Introduction Different type of flaw opening type of loading
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
a) tensile stress b) shear stress parallel c) shear stress
perpendicular to to the plane of crack parallel to the plane
the plane of crack and perpendicular to of crack and of its
its edge edge
42
Influence of surface flaws
Objectives
Introduction
Historical review
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
Typical short-term strengths as a function of the flaw depth
43
Strength of glass
Objectives
Introduction
Glass used as Plate or Beam
Historical review
PLATE BEAM
Production
Chemical
composition
Glass products,
edge quality
Material and
mechanical
properties
Strength of
annealed glass
planar surface loading edge loading
codes available edge = damage
no codes
need of experiments
Edges of annealed glass weaker than its flat surface annealed
glass beams designed to lower stresses in comparison with glass
plates
44
References
Educational pack of COSTActin TU0905 Structural Glass - Novel design methods and next generation
products
HALDIMANN, Matthias; LUIBLE, Andreas; OVEREND, Mauro.
Structural Use of Glass. Structural Engineering Documents 10 , IABSE, Zrich:2008. ISBN 978-3-85748-
119-2
RICE, Peter; DUTTON, Hugh.
Structural Glass, E & FN SPON, 1995.
WIGGINGTON, Michael.
Glass in Architecture, Phaidon Press, 1996.
KNAACK, Ulrich.
Konstruktiver Glasbau, Rudolf Mller, 1998.
SCHITTICH, Christian; STAIB, Gerald; BALKOW, Dieter; SCHULER, Matthias; SOBEK, Werner.
Glass Construction Manual, Basel: Birkhuser Edition Detail, 1999.
NIJSSE, Rob.
Glass in Structures, Birkhuser, 2003.
KALTENBACH, Frank.
Transluzente Materialien, Detail Praxis Edition Detail, 2004.
WURM, Jan.
Glass Structures Design and construction of self-supporting skins, Basel-Boston-Berlin: Birkhuser,
2007.
THE INSTITUTION OF STRUCTURAL ENGINEERS
Structural use of glass in buildings, London: The institution of Structural Engineers, 1999.
45
This lecture was prepared for the 1st Edition of SUSCOS
(2012/14) by Prof. Sandra Jordo (UC).
Adaptations brought by Prof. Viorel Ungureanu (UPT) for
2nd Edition of SUSCOS
46
Thank you
for your kind attention
viorel.ungureanu@upt.ro
http://steel.fsv.cvut.cz/suscos
