RICE
ENGINEERING
Custom
Structural
Glass
Engineering
Codes around the World
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USA
-ASTM E1300 (Only real Code)
-GANA (Glass Association of
North America)
-AAMA Structural Properties of Glass
Canada
-CAN/CGSB – 12.20 – M89
British
-BS 6262
Australia
-AS1288-1994
The Netherlands
-NEN 2608 and 2608A
Germany
-DIN 18008 Standard
Austrian
-OORM 3716
Current References
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Structural Use of Glass in
Buildings – Institute of
Structural Engineers 1999
Structural Use of Glass –
International Association for
Bridge and Structural
Engineering 2008
Laminated Glazing Reference
Manual – GANA 2009
GANA Glazing Manual 50th
Anniversary Edition 2010
Fully Tempered Heavy Glass
Door and Entrance Systems
Design Guide – GANA 1999
Glass Properties

Glass Properties – 60 Sec.
Duration Period
Note: Can multiply stress allowable by 1.21 to convert
to 3 sec duration
Mean Modulus of Rupture (50% Breakage) is twice
8:1000 Break Strength
8:1000 Stress used typically for standard insulated
glass units
1:1000 Stress typically specified by Architects/EOR to
provide more conservative results and are found in
specifications
Glass Properties

Glass Properties – FEA Analysis
Note: We use the max. of the ranges as specified above…
Tempered = 6,000 psi max.
Other Properties
Weight = 158 lb/cu. Ft.
Modulus of Elasticity (E) = 1.04 x 10^6 psi
Modulus of Rigidity (Shear) = 4.3 x 10^6 psi
Poisson’s Ratio = 0.22
Coefficient of Thermal Expansion = 4.6 x 10^-6 in/in F
Glass Edge Bearing Stress
Annealed Glass
= 72 psi
Heat-Strengthened Glass = 144 psi
Tempered Glass
= 216 psi
Unique Design Values
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Surface Bearing = 3,000 psi
Shear = 3,000 psi (Mohr’s Circle)
Bearing Stress within Plane =
Tempered
3,916 psi
Heat-Strengthened
2,611 psi
Annealed
1,305 psi
Peterson’s Stress Concentration
Factor = 2.0
Glass Deflection typical – L/120 max.
Glass Floor Panels – L/500 max.
Any member that supports glass – L/175
or ¾” max. with the lesser value
governing per (IBC).
Full Bearing shims are denoted as Shore
A, +/- 85 Durometer (GANA)(AAMA)
In-Plane Bearing
Methods of Glass
Analysis
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1.
2.
3.
4.
5.
6.
Risa-3D Analysis
Submesh typically set to about an 1 sq
in
Monolithic panels used with properties
Laminate (Interior) set as 90%
composition
Laminate (Exterior) set as 75%
composition
Results based upon max. Von Mises
Results between Risa & Mepla typically
comparable with Risa being
conservative
Methods of Glass
Analysis
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1.
2.
3.
4.
5.
SJ Mepla Analysis
Submesh for panels typical set at min.
the thickness of the panel similar to
methods used in Algor analysis
Coordinates for panels are to always be
entered in a counter clock-wise direction
Gravity must always be entered…rotate
panel for application
Base results on max. principal stresses
Must select laminate temperature in
order for the composition to act properly
under design loads
SJ Mepla allows you to vary
temperature and realize its effects to
the laminate composition
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Wind – Typically 3 sec duration
Snow – Typically 1 month
Live Load – Typically 1 day
Methods of Glass
Analysis
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1.
2.
3.
4.
5.
WinGlass Design (ASTM
E1300)
Due to limited aspect ratios for glass it’s
use is limited.
Geared toward mainly insulated units
with 4-Sided support and can analyze
laminated panels
Also has options for 2 & 3 sided support
Does not allow for changing your
Probability of Breakage.
Software used primarily for insulated or
monolythic glass panels loaded for Wind
Load Only in window applications
Methods of Glass
Analysis
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1.
2.
3.
“Good Ole Statics”
Always yields conservative results that
can typically be trusted….
Templates can be used to throw out
good conservative analysis to clients
Allows you to refine your results via
Risa-3D or SJ Mepla
Glazing Bite Recommendations
Glazing Bite Recommendations
Glass Handrails
Rules of Thumb
1.
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Structural Panel Glass Railing
Typical ½” tempered panels are standard…per
code ¼” thickness min. can be used
Structural Glass Panel systems to be laminated
panels (Tempered or Heat-Strengthened min.)
or single monolithic panels (Tempered only) per
IBC 2009
Code states that panels must be connected via
handrail 3 or more spans, but gives you the
option to use laminated panels with no handrail
Max. Deflection limit on glass set to L/90 or
2L/90 for canti-lever application – (Differential
deflection is to still be checked if panels are
free)
1” max. limit set for guardrails for comfort under
200 lb Live Load
1 ½” max. limit allowed for Uniform Loading
(Wind Load Deflection)
Recommended that top edges of both systems
are to be protected, though not required by
code at this time.
Typically analyzed statically or FEA with Risa-3D
Glass Canopies
Rules of Thumb
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Deflection held to L/120 max.
Panels must be laminate for safety,
though layers are not broken for
redundancy as glass floors. (GANA) (IBC)
Typically all canopy applications are to be
laminated glass due to overhead
condition unless protective screens are
installed (IBC)
Typically analyzed statically or FEA with
Risa 3D or SJ Mepla…setting conditions
usually determine program
IBC Chapter 24 has extra load constraints
that must be checked with Combined
Load Criteria – (IBC typically governs)
Code Recommendations
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IBC 2009
Typical Glass Walls
Rules of Thumb
Typically panels are single sheets
monolithic but can be laminated panels if
they are large enough….
 IBC 2009
Section 2403 – Differential deflection no
greater than the thickness of the panel
when 50plf is applied up to 42” off finish
floor
Framing to be held to L/175 (3/4” max.)
 L/120 max. Deflection allowed
 Analysis should be performed in SJ Mepla
for it has the most control over custom
anchorage at panel edges, though RISA3D can be used as well.
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Point Supported Walls
Rules of Thumb
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L/120 deflection criteria applies
Fittings typically set no closer
than 2 diameters min. from
edge
Analysis performed within SJ
Mepla exclusively in order to
accurately mimic the point
fittings for application
Glass Beams/Fins
Rules of Thumb
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Beams supporting constant DL
shall be laminated
Fins for WL can be monolythic
Interior 5 PSF fins are typically
single sheets but you can
expect laminate fin design for
exterior applications
Lateral Torsional Buckling
checks incorporated in
templates
L/300 Deflection Criteria
SF of 2.4 for Permanent DL
Intermediate Restraints
No Restraints
Glass Panels (Axial
Compression)
Rules of Thumb
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Laminate design required for
safety/redundancy
Typically panels are 3-Ply
laminate minimum
Axial Buckling Check set in
templates for analysis
Analysis performed within SJ
Mepla or Risa-3D
Glass Floors
Rules of Thumb
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L/500 deflection limitation used
Laminated design required for
safety
Upper panel of composition to
be removed for design
(redundancy)
ASTM E2751 Glass Floor
Criteria Exists
Glass Stairs
Rules of Thumb
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L/500 deflection limitation used
Laminate design required for
safety
Upper panel of composition to
be removed for design
(redundancy)
Channel Glass
Rules of Thumb
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Deflection held to L/100 max.
System considered to act as Insulated
Unit where you get multiple channels
effective
Structural silicone used typical to seal
entire system
Bendheim has been developing new
aluminum extrusions to make their
systems have more of a finished
curtainwall look
Channels are either annealed or
tempered
Typically analyzed statically with Risa-3D
plate models if needed