Saflex Structural Guide

StructuralPub. No. 2458043A

(Supercedes No. 2458043)

A SAFLEX DESIGN GUIDEFOR ARCHITECTURAL

GLAZING SYSTEMS

Structural Performanceof Laminated

Architectural Glass

ACKNOW LEDGEMENTSThis design guide was prepared by Solutia Inc.

using results from extensive research conducted

at the Glass Research and Testing Laboratory

at Texas Tech University and the Building

Envelope Research Laboratory at the University

of Missouri-Rolla. Contributions by individuals

at these two research institutions are gratefully

acknowledged: Dr. Joseph E. Minor, Dr. H. Scott

Norville, Dr. C.V.G. Vallabhan, Dr. Richard A. Behr,

Mr. Magnus P. Linden, Mr. Sesha R. Nagalla, and

Mr. Paul Kremer. Matching contributions by Texas

Tech University, the University of Missouri-Rolla

and the States of Texas and Missouri through

programs that assist university/industry

cooperative efforts are also acknowledged.

FOREWORDA Design Guide to the Structural Performance of Laminated

Architectural Glass (the Guide) was developed to provide

the designer with the latest information and data on the

performance of this glazing product.

The Guide provides a new, technically sound basis for the

structural design of architectural glazing systems under

a wide range of environmental conditions. Since wind

and snow govern the design of most architectural glaz-

ing systems, special attention is given to these loads. In

addition, windborne debris that accompanies hurricanes,

typhoons and other extreme windstorms has become

recognized as an important factor in the performance

of the building envelope. Hence, new attention is given

to designs for windborne debris – a condition in which

laminated architectural glass is especially effective.

Testing in the 1980s at Texas Tech University revealed

that laminated architectural glass fabricated with Saflex

polyvinyl butyral (PVB) plastic interlayer is as strong

as monolithic glass under wind and snow loads. In

the 1990s, building codes and standards began to

emphasize protection of the building envelope from

windborne debris in extreme wind prone regions.

Te sting at the University of Missouri-Rolla defined the

attributes of laminated glass that enable it to perform

effectively in this new application. These two develop-

ments have projected laminated architectural glass as

the product of choice for a strong, “passive” window

system under wind, snow and debris impact.

The newly reported research and new provisions in

building codes and standards noted above are incorpo-

rated into the Guide. The new procedures make it possible

to design architectural glazing for wind and snow loads

using a simple process, to address designs for windborne

debris, and to employ the strengths and attributes of

laminated architectural glass in protecting the building

envelope from a wide range of environmental and

man-made hazards.

The Guide provides anew, technically soundbasis for the structuraldesign of architectural glazing systems under a wide range of envi-ronmental conditions.

Introduction

Structural DesignMethods

Structural Performance of Laminated Architectural Glass cont

ents

Listing of Figures and Tables 2The Changing Design Environment 3Attributes of Laminated Glass 3Research Results 3New Design Methods 3Purpose of the Guide 4Organization of the Guide 4

Appendix

Charts A.1-A.12 Glass Thickness Selection Charts 39Charts A.13a-A.13i Deflections in Glass Plates 41Table A.14 Load Sharing in Asymmetrical IG Units 43Table A.15 Thickness Designations for

Laminated Glass 43Table A.16 Equivalent Monolithic Glass Thickness

for Laminated Glass under Long-Term Load at Room Temperature 43

Abbreviations 44Symbols 44Glossary 45References 46Specification 48

Closure Summary 38The Future 38

Introduction 5Simple Design Procedure: Wind and Snow 6Comprehensive Design Procedure 10Designs for Windborne Debris 17Additional Design Requirements: 22

Earthquakes 22Human Impact 22Human Loads 23Hail Impacts 23Overhead Glazing 24

Laminated Glass Behavior

Research Summary 28Lateral Pressure 28Verification of Computer Programs 29Laminated Glass Behavior 30Time Duration of Load Effects 30Interlayer Thickness 31Failure Strengths 31Impact Strength 32

WindborneDebris

Windstorm Experiences 33Hurricanes and Typhoons 34The Nature of Windborne Debris 35The Building Envelope 35Post-Breakage Behavior 36Test Protocols 36Research and Development 37Laminated Architectural Glass 37

Basic Factors in Glass Strength

Annealed Glass Strength 25Glass Type Factors 25Load Duration 26ASTM E1300-97 26Impact Strength 27

1section

2section

3section

4section

2

Figure Title Page1 Window Glass Design Chart

(Symmetrical Products – 4-Side Support) 7

2 Window Glass Design Chart (Symmetrical Products – 2-Side Support) 9

3 Butt Glazed System 94 Deflection Calculations Chart (6 mm) 135 Symmetrical Laminated Glass 146 Laminated Insulating Glass Unit 14

7a Laminate Acting as Monolithic 16

7b Laminate Responding as Layers 16

8a Strength – Room Temperature 16

8b Strength – Elevated Temperature 16

9 Areas Requiring Consideration of Debris Impact 18

10 Glazing by Construction Glass Industries Inc. 20

11 Glazing Detail Passing Small Missile Impact Test 21

12 Glazing Detail for Small Missile Impact 21

13a Tempered Glass 25

13b Stress Distribution in Fully Tempered Glass 25

14 Effect of Load Duration on Glass Strength 26

15 Glass Plate Systems 28

16a Monolithic Maximum Stress 29

16b Monolithic Deflection 29

16c Layered Maximum Stress 29

16d Layered Deflection 29

17a Maximum Stress 30

17b Deflection 30

18 Effects of Sustained Load: Maximum Deflection 30

19a Maximum Stress 31

19b Maximum Deflection 31

20 Houston, Texas – Hurricane Alicia 33

21 Miami, Florida – Hurricane Andrew 33

22 Hurricane/Typhoon Wind Field 34

23 Breaching of the Building Envelope Doubles Forces 35

24 Silicone Anchored LAG 37

25 Sacrificial Ply LAG 37

Table Title Page1 Table of Factors 7

2 Requirements for Windborne Debris 18

3 Establish Debris Impact Criteria 19

4 Select Glazing Concept or Product 20

5 LAG Constructions That Meet Missile Impact Standards and Codes 20

6 Qualify Concept or Product for Use 21

7 Safety Glazing Requirements – Consumer Products Safety Commission 23

8 c2 Factors for Glass Floors 23

9 Strength Factors 26

10 Average Minimum Impact Velocity Causing Fracture 27

11 Inner Ply Breakage Rates in LAG Under Impacts 27

12 Impact Resistant LAG Constructions 27

13 Failure Strengths of AN Monolithic and LAG at Room Temperature 31

14 Failure Strengths of AN Monolithic and LAG as a Function of Temperature 31

15 Failure Strengths of AN, HS and FT LAG 32

16 LAG Breakage Rates as a Function of Interlayer Thickness and Heat Treatment 32

17 Typical Standard for Windborne Debris Impact Tests 36

A.14 Load Sharing in Asymmetrical IG Units 43

A.15 Glass Thickness Designations for Laminated Glass 43

A.16 Equivalent Monolithic Glass Thickness for Laminated Glass under Long-Term Load at Room Temperature 43

Listing of Figures, Charts and Tables

Chart Title PageA.1-A.12 Glass Thickness Selection Charts 39

A.13a-A.13i Deflections in Glass Plates 41

3

THE CHANGING DESIGN ENVIRONMENTRecent windstorm disasters have focused attention onthe building envelope (windows, doors, wall coveringsand roof cladding) as an important part of any enclosedstructure. Failures of the building envelope during wind-storms have produced unacceptably large insured lossesand have sharpened awareness toward hazards presentedby falling glass. This new attention to the building envel-ope has produced building code changes and forced a reexamination of design methods for architecturalglazing. The fluctuating nature of wind pressures andthe presence of windborne debris in some extreme wind events are now being addressed as part of thedesign process. Perhaps most significantly, the post-breakage behavior of architectural glazing has become a crucial element to successful construction in the newdesign environment.

ATTRIBUTES OF LAMINATED GLASSTwo attributes of laminated architectural glass make thisproduct attractive in the new design environment. First,recently completed research has shown that the strengthof laminated architectural glass under wind and snowloads is equivalent to that of monolithic glass of thesame nominal thickness. Second, the ability of lami-nated architectural glass to remain in its supportingframe following breakage by windborne debris, or byunexplained events, is important to the preservation ofthe integrity of the building envelope and to the limita-tion of hazards to people who may occupy space below.

RESEARCH RESULTSResearch conducted at the Glass Research and TestingLaboratory at Texas Tech University provides a basis forthe strength of laminated architectural glass defined inthis Guide. Theory has been verified by experiment, andexperiments were both non-destructive and destructive(tests to failure).

Full-scale experiments performed at the BuildingEnvelope Research Laboratory at the University ofMissouri-Rolla established the ability of laminated architectural glass to accept debris impacts and toremain in the opening during the application of pressure cycles representing wind gusts that follow. In addition, full-scale tests established the superior performance of laminated architectural glass in earth-quake environments.

NEW DESIGN METHODSThe new design environment and the attributes of laminated architectural glass defined by recent researchresults have altered conventional approaches to designfor architectural glazing. A simple approach to designingfor wind and snow is outlined first. This procedure isbased on observations that laminated architectural glassacts like monolithic glass under these design conditions,and that most insulating glass units are “thin and sym-metrical.” A comprehensive design procedure is offeredfor the small percentage of design situations that do notmeet these conditions. A new design method for wind-borne debris recognizes new requirements in the SouthFlorida Building Code, ASCE 7-98, The BOCA NationalBuilding Code, the Texas Department of InsuranceBuilding Code for Wind Resistant Construction, andan increasing number of municipal codes. Finally, infor-mation is presented for earthquakes, human impact,human loads, hail, and overhead glazing to assist thedesigner in addressing these topics.

Introduction

4

PURPOSE OF THE GUIDEThis publication has been prepared for the buildingdesign professional by Solutia Inc., manufacturer ofSaflex® polyvinyl butyral (PVB) plastic interlayer for laminated architectural glass. The principal purpose of this publication is to present easy-to-follow guidelinesfor designing laminated glass systems with Saflex forwind, snow, impact, earthquake and other loads. Thesemethodologies are devised to enable the architect andengineer to develop designs of glazing systems usinglaminated architectural glass in a logical and a rationalmanner. The need for the Guide is enhanced by themore extensive use of laminated architectural glass in glass curtain walls, storefront facades, atriums, skylights, canopies and other glazing systems.

ORGANIZATION OF THE GUIDETo provide a “user friendly” design tool, the Guide hasbeen organized as follows:

Section 1 contains (1) a simple design method for wind and snow, (2) a comprehensive design procedure for lateral pressures, and (3) a design method for windborne debris. Information is also presented for earthquakes, human impact, human loads, hail, and overhead glazing. The design methods are presented in condensed formats.Supporting data are contained in subsequent sections and the Appendix.

Section 2 contains discussions of factors which areimportant to the definition of strength for annealed glass, laminated architectural glass, heat treated glass and insulating glass. Effects of the time duration of loading on glass strength are included in these discussions.

Section 3 summarizes extensive research on laminatedarchitectural glass that was used as a basis for thedesign guidelines contained herein.

Section 4 contains information on windborne debristhat is currently being addressed in national standards and building codes (ASCE 7-98, the BOCA National Building Code, SBCCI SSTD 12-97, ASTM E1886-97 and TDI 1-98), as well as in the South Florida Building Code and anincreasing number of municipal building codes in hurricane-prone regions.

The Appendix contains design charts, laminated glassthickness designations, abbreviations, symbols, a glossary, lists of references, a model specificationand other supporting information.

Introduction

5

Structural Design Methods 1section

INTRODUCTIONArchitectural glazing products are employed in a myriad of situations that require structural design.Windows, spandrel units, skylights, doors, storefronts,atriums, greenhouses, passageways, side lites, and manyother uses of glazing each has its own requirements fordesign. These requirements may involve combinationsof loads (wind, snow, dead, live), as well as additionalconditions involving earthquakes, human impact,human loads, and hail.

Since most glazing designs are governed by wind loadsor snow loads, this section of the Guide begins with asimple approach to the design of common architecturalglazing products for wind and snow. This simple designmethod is followed by a comprehensive design proce-dure for all products that experience lateral pressure,including wind and snow. A new design procedure – a method of design for impacts from windborne debris –is presented next. Finally, many products must also bedesigned for earthquakes, human impact, human loads,and hail. Design methods for these additional condi-tions are addressed in the final part of Section 1.

The Simple Design Procedure addresses the most commonly occurring design loads: wind and snow. These loads dominate and control many designs; hence, the simple procedure presented in this method will be sufficient for most glazing design situations.

The Comprehensive Design Procedure addresses design cases with lateral pressures that cannot be handled by the simple procedures. For example, this procedure can be used to design overhead glazing for snow loads using an asymmetrical insulating glass unit.

Designs for Windborne Debris is a new procedure that will assist designers with requirements that are appearing in national standards and building codes. The procedure helps the designer determinewhen windborne debris must be addressed, the impact criteria that may apply, design concepts and glazing products that can resist debris impact, and test protocols that can be used to qualify products for use in situations requiring considera-tion of windborne debris.

Additional Design Requirements address conditions that may influence products that have already been designed for wind and/or snow loads. Earthquakes, human impact, human loads (e.g., people walking on glass floors), hail and overhead glazing are addressed in this part of Section 1.

6

SIMPLE DESIGN PROCEDURE: WIND AND SNOWThe design of an architectural glazing product thatemploys monolithic and/or laminated architectural glass (LAG) can be very complex. However, if the glazing product meets the following conditions, designing it for wind and snow loads is very simple:

1 its aspect ratio is 2:1 or less (length ÷ width ≤ 2)

2 it is comprised of monolithic glass or LAG withsymmetrical* plies, and

3 if the product is an insulating glass (IG) unit, it is symmetrical* with thin lites.

Note: A LAG lite has two glass plies and an IG unit hastwo glass lites. One or two LAG lites can be used in anIG unit. See Glossary.

Simplicity is achieved because:■ the 12 annealed (AN) glass strength charts from

ASTM E1300-97 Standard Practice for Determiningthe Load Resistance of Glass in Buildings (Reference1.1) have been reduced to a single chart for aspectratios of 2:1 or less (see Window Glass DesignChart – 4-Side Support);

■ lites in IG units share loads equally when the litesare both symmetrical and thin (see Section 2);

■ LAG behaves like monolithic glass under wind and snow loads (see Section 3); and

■ dead loads do not exist (vertical glazing) or can be neglected (sloped glazing)** and glass must not be subjected to “live” loads.

* Plies (LAG) or lites (IG) of same glass type with identical designated thickness are symmetrical.

** For example, a 1/4-inch glass plate weighs less than 3 psf; typical design wind and snow loads exceed 30 psf.

PROCEDURE (Symmetrical*, 4-Side Support) See Design Chart and Table of Factors on Page 7

Step 1 Obtain design load from building code: windload or snow load (lbs/ft2 or kPa).

Step 2 Calculate opening area (L x W) in ft2 or m2

and aspect ratio (L ÷ W).

Step 3 Check for Simple Design Procedure(L ÷ W must be ≤ 2).

Step 4 For AN, HS or FT glass, divide design load byappropriate strength factor: 1 (AN), 2 (HS) or 4 (FT), respectively (see Table page 7).

Step 5 If product is an IG unit, also divide by IGstrength factor: 2*** (see Table page 7).

Step 6 Divide load from Step 4 or 5 by appropriatetime factor*** (see Table page 7 for time factor);the result is the modified design load*** inlbs/ft2 or kPa.

Step 7 Use opening area (from Step 2) and modifieddesign load (from Step 6) to define a point inthe Design Chart on page 7.

Step 8 Required overall lite thickness is the thickness (t)associated with a line corresponding to theaspect ratio (from Step 2) that is “above-right”of the point defined. If the aspect ratio (fromStep 2) is other than 1:1 or 2:1, draw a line(between the 1:1 and 2:1 lines) for the specificaspect ratio calculated. Linear interpolationbetween 1:1 and 2:1 lines for a given thicknessprovides acceptable accuracy.

Step 9 If IG unit, verify that lites are “thin” (W÷t)>150where W = width (short dimension) and t =thickness of one lite.

*** If ASTM E1300-97 must be followed:Step 4: If LAG is used as a single lite, also divide by 0.9 (short

duration load) or 0.75 (long duration load). Step 5: Divide by 1.8 instead of 2 (for IG unit).Step 6: If design load is a wind load, do not divide by time factor.

Structural Design Methods

7

NOTES TO FIGURE 1 – DESIGN CHART: 1 Plies (LAG) or lites (IG) of same glass type with identical designated thickness are symmetrical.2 Glass strengths in the chart are 60-second duration glass strengths obtained from ASTM E1300-97

for aspect ratios (length ÷ width) of 2:1 or smaller.3 Linear interpolation between 2:1 and 1:1 lines for intermediate aspect ratios provides acceptable

accuracy.4 Glass strengths may be adjusted by time factors to account for changes in glass strength from

60-second to 3-second (wind) and to two-week (snow) load durations. (If ASTM E1300-97 is followed, product strengths for wind loads must be determined by using 60-second strengths.)

5 The Simple Design Procedure uses 1.0 as a strength factor for LAG and 2.0 as a strength factor forIG. If ASTM E1300-97 is followed, strength factors for LAG of 0.9 (short duration load) and 0.75(long duration load) and a strength factor for IG of 1.8 must be used; see Footnotes, page 6.

6 If deflections must be calculated, see Comprehensive Design Procedure, Procedure 3.7 If the glazing product is an IG unit placed over an occupied space that is or may be heated, the

interlayer temperature in the lower (LAG) lite may be >32˚F when under snow load. In this case, the Comprehensive Design Procedure, Procedure 2, must be followed.

1

60-Second Strength – kPa

60-Second Strength – PSF

Open

ing

Area

– S

quar

e M

eter

s

Open

ing

Area

– S

quar

e Fe

et

0.4 0.5 0.6 0.7 0.8 0.9 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

9

0.5

0.3

0.7

0.80.91.0

2.0

3.0

4.0

5.0

6.0

7.0

8.09.0

10.0

5

6

78910

20

30

40

50

60

708090100

10 20 30 40 50 60 70 80 90 100 200

M Denotes Monolithic Nominal Thickness Designation

L Denotes Laminated Nominal Thickness Designation

1/8 in. (3 mm – M)3/16 in. (5 mm – M & L)

1/4 in. (6 mm – M & L)

5/16 in. (8 mm – M & L)

3/8 in. (10 mm – M & L)

1/2 in. (12 mm – M & L)

5/8 in. (16 mm – M & L)

3/4 in. (19 mm – M & L)

7/8 in. (22 mm – M & L)

2-11-12-11-1

1-12-11-1

2-1

1-1

2-1

1-1

2-1

1-1

2-1

1-12-1

2-11-1

2-11-12-11-1

2-11-1

2-11-1

2-11-1

2-1

1-11-12-11-1

2-1

1-1

2-1

FIGURE 1 Window Glass Design Chart (Symmetrical Products – 4-Side Support)

TABLE 1 Table of FactorsGlazing Strength Time FactorsProduct Factor Wind Snow

AN 1.0 1.2 0.6

HS 2.0 1.6 0.8

FT 4.0 1.8 0.9

IG 2.0

LAG 1.0

8

EXAMPLES (follow procedure on page 6)Find required lite thickness for a symmetrical IG unit comprised of HS LAG. Opening is

5 ft. x 8 ft. and 3-second design wind load is 100 psf.

Step 1 3-second wind load = 100 psf.

Step 2 Opening area: 5 ft. x 8 ft. = 40 ft.2

Step 3 Aspect ratio: 8 ÷ 5 = 1.6:1 (1.6 < 2; OK for Simple Design Procedure)

Step 4 100 ÷ 2 = 50 psf (HS strength factor = 2).Use 100 ÷ 1.8 (IG) ÷ 1.8 (HS LAG, short durationload) = 31 psf if E1300-97 must be followed.

Step 5 50 ÷ 2 = 25 psf (IG strength factor = 2).

Step 6 25 ÷ 1.6 = 17 psf (HS time factor = 1.6).Do not use wind time factor for HS glass (1.6) if E1300-97 must be followed.

Step 7 40 ft2 and 17 psf define a point within the 3/16-inch thickness lines but above a 1.6:1 lineinterpolated between the 1:1 and 2:1 lines.For E1300-97, 40 ft.2 and 31 psf define a pointwithin the 5/16-inch thickness lines but above a1.6:1 line interpolated between the 1:1 and 2:1 lines.

Step 8 Required thickness of each HS LAG lite in the IGunit is 1/4-inch (overall “designated thickness”) For E1300-97, required thickness of each HS LAGlite in the IG unit is 3/8-inch (overall “designatedthickness”).

Step 9 60 ÷ 0.25 = 240 (240 > 150); “thin lite”.60 ÷ 0.375 = 160 (b/t=160 > 150)

Find required lite thickness for a HS LAG liteover an unheated occupied space. Opening is

54 inches x 81 inches and design snow load is 62 psf.

Step 1 Snow load = 62 psf.

Step 2 Opening area: (54 x 81) ÷ 144 = 30.4 ft.2

Step 3 Aspect ratio: 81 ÷ 54 = 1.5:1 (1.5<2; OK for Simple Design Procedure)

Step 4 62 ÷ 2 = 31 psf (HS strength factor = 2).Use 62 ÷ 1.2 (HS LAG, long duration load) = 52 psf if E1300-97 must be followed.

Step 5 (Not an IG unit.)

Step 6 31 ÷ 0.8 = 39 psf (HS time factor = 0.8).

Step 7 30.4 ft.2 and 39 psf define a point within the5/16-inch lines, near the 1:1 line.For E1300-97, 30.4 ft.2 and 52 psf define a pointabove the 3/8 in. lines.

Step 8 Interpolated 1.5:1 line passes below definedpoint; use 3/8-inch HS LAG (overall “desig-nated thickness”).For E1300-97, required thickness of HS LAG is 1/2-inch (overall “designated thickness”).

Step 9 (Not an IG unit.)

12


9

PROCEDURE (2-Side Support)

Step 1 Obtain design load from building code: windload or snow load.

Step 2 Determine length of unsupported span (U) in inches.

Step 3 For AN, HS or FT glass, divide design load by 1 (AN), 2 (HS) or 4 (FT), respectively (see Tablepage 7).

Step 4 If product is a symmetrical IG unit, also divideby 2 (see Table page 7).Note: It is not common practice in North America to use IGunits in 2-side support configurations.

Step 5 Divide load from Step 3 or 4 by appropriatetime factor (from Table page 7); this is the modified design load.

Step 6 Use length U (from Step 2) and modifieddesign load (from Step 5) to define a point on the design chart (Figure 2 above).

Step 7 Read minimum allowable overall lite thickness.If point falls between two thicknesses, choosethe thicker lite thickness.Note: ASTM E1300-97 does not address 2-side support conditions.

Length of Unsupported Span – Inches

Desig

n Lo

ad –

lbs./

sq. f

t.

20

1020 40 60 80 100

30

40

50

60

70

80

90

100

Example:60" x 30" (60" Unsupported)p = 30 psfUse 5/8"

3/16"1/4"

5/16"3/8"

1/2"5/8"

3/4"

U

Head

Sill

Butt Joints

U = Unsupported Span

1FIGURE 2 Window Glass Design Chart

(Symmetrical Products – 2-Side Support)FIGURE 3 Butt Glazed System

10

COMPREHENSIVE DESIGN PROCEDUREGlazing products that do not meet the conditions forusing the “simple” procedure for wind and snow loadsmust use a more detailed analysis. The comprehensivedesign procedure presented herein uses the ASTM E1300-97 annealed glass strength charts, but differs from theother data in the ASTM process in two importantrespects. First, the strength of laminated architecturalglass (LAG) is defined by recent research that recognizesLAG strengths that are equivalent to monolithic glassstrengths under wind and snow loads (see Section 3,Laminated Glass Behavior). Second, the increasedstrength of glass under wind loads (which are shorter in duration than the 60-second duration employed inASTM E1300-97 strength charts) is recognized. Becauseof these adjustments, strengths of glass products calcu-lated using procedures outlined in the comprehensivedesign procedure will not be the same as strengths calcu-lated using ASTM Standard E1300-97.

The comprehensive design procedure is divided intofour parts. Procedure 1 addresses monolithic glass, LAG, and IG units with lites that share load equally;Procedure 2 handles IG units with unequal load shar-ing; Procedure 3 treats the calculation of deflections.Special cases using LAG are treated in Procedure 4.

Procedure 1 addresses all monolithic glass, LAG made with plies of the same glass type, and IG units thatare symmetrical (lites identical in glass type andthickness, including LAG lites equal in designatedthickness to their monolithic companions).

Procedure 2 handles asymmetrical IG units, IG unitswith “thick” lites, and IG units with LAG thatmust be treated as “layered” (e.g., a LAG lower lite of an IG unit under snow load that is over anoccupied space that may be above 32˚F).

Procedure 3 treats deflections in monolithic glass, LAG and IG units of all types.

Procedure 4 treats special cases of LAG design that use different ply thicknesses and glass types.

The comprehensive design procedure addresses wind andsnow loads only, as dead loads do not exist (verticalglazing) or can be neglected (sloped glazing), and glassmust not be subjected to “live” loads. Combinations of wind and snow loads, when required, are treated by converting each load to an equivalent 60-secondduration load and adding effects according to the com-bination formulas contained in standards and codes.

If ASTM E1300-97 or building codes which do not recognize the science employed in the comprehensivedesign procedure must be followed, notes at appropriatepoints in the presentation indicate adjustments thatmust be made.


11

PROCEDURE 1:Monolithic and Laminated Glass, and Insulating Glass Units With Symmetrical LitesIncludes LAG containing plies with same heat treatment,and IG with lites of same glass type and designated thickness(including IG units with one LAG lite).

Approach: Modify the design load to account for glasstype and time duration of load, select a trial thickness,enter the corresponding chart using opening dimen-sions, and compare the chart defined strength with themodified design load; proceed to a thicker or thinnerthickness chart, as necessary, to “close” on an acceptablethickness.

Step 1 Obtain design load from building code: windload and/or snow load. (Note: if wind and snowdesign load combinations must be considered, seenote in Step 4.)

Step 2 Determine opening dimensions (L = longdimension and W = short dimension).

Step 3 For monolithic glass, LAG and IG units withAN, HS, or FT glass, divide the design load by 1 (AN), 2 (HS) or 4 (FT), respectively. If productis an IG unit, also divide by 2*.

Step 4 Divide modified design load from Step 3 byappropriate time factor: 1.2 (AN), 1.6 (HS), or1.8 (FT) for wind load, or 0.6 (AN), 0.8 (HS), or0.9 (FT) for snow load.* (Note: if load combina-tions must be considered, perform the conversionsas described for both wind and snow, and addaccording to the load combination formula.)

Step 5 Select a trial thickness and find the correspond-ing chart in the Appendix, Charts A.1-A.12.(The trial thickness is a designated monolithicor LAG thickness, and is the thickness of onelite if the glazing is an IG unit; ASTM C1036designated thicknesses are contained in theAppendix, Table A.2.) Draw a vertical line from“L” and a horizontal line from “W”; the inter-section of these lines represents the strength ofthe trial thickness (in kPa) for the glazingbeing designed. (Interpolation between loadlines along a radial line from the chart origin may be necessary.)

Step 6 If the strength of the trial thickness is larger(smaller) than the modified design load, moveto a thinner (thicker) glass thickness chart andrepeat Step 5. Repeat this process until a glassthickness is found that exhibits a strength thatis the same as or slightly larger than the modi-fied design load.

Step 7 If the glazing design is an IG unit, divide theshort dimension (W) by the designated thick-ness of one lite. If this number is >150, the IGunit design is acceptable; if not, the IG unitdesign is too thick to behave as a symmetricalunit and Procedure 2 must be used.

* ASTM E1300-97 combines strength factors and time factors into fourtables of “glass type (GT) factors”: single lites (monolithic and LAG) andIG, for short and long duration loads. To adjust the comprehensivedesign procedure (Procedure 1 only) to ASTM E1300-97, strength factorsand time factors must be separated. ASTM E1300-97 uses the followingstrength factors: 1 (AN), 2 (HS), 4 (FT), 1.8 (IG; monolithic, symmetricallites), 0.9 (LAG, AR ≤ 2 and b/t > 150; short duration load), 0.75 (LAG,AR > 2 or b/t ≤ 150; short duration load), 0.75 (LAG, AR ≤ 2.5; long dura-tion load), 0.5 (LAG, AR > 2.5; long duration load). ASTM E1300-97 mod-ifies strength factors by time factors for long duration loads: 0.6 (AN),0.8 (HS), 0.9 (FT). Note: ASTM E1300-97 does not specifically address IGwith two LAG lites and does not include a time factor for a 3-secondwind load. In ASTM E1300-97: aspect ratio (AR) = long dimension ÷ shortdimension, b = short dimension, short duration load lasts 60 seconds orless, and long duration load lasts approximately 30 days.

1

12

PROCEDURE 2:Asymmetrical Insulating Glass UnitsIncludes IG units with lites of different thickness and/or heattreatment, “thick” IG units, and IG units with lite(s) of LAGthat must be considered “layered”.

Approach: Establish a trial design by defining glass typesand thicknesses; apportion design load between litesand modify the apportioned loads by strength and timefactors, as appropriate. Enter charts to determine ifstrengths of lites in trial design exceed modified appor-tioned design loads.

Step 1 Obtain design load from building code: windload and/or snow load. (Note: if wind and snowdesign load combinations must be considered, seenote in Step 5.)

Step 2 Determine opening dimensions (L and W); W is the short dimension.

Step 3 Establish a trial design by defining the asym-metrical IG unit as follows: select a trial thick-ness tL for the loaded (outer) lite; select a trialthickness tU for the other (inner) lite; select atrial glass type (AN, HS, or FT) for each lite.

Step 4 Calculate tU ÷ tL and W ÷ tL. (Note: if lower liteis LAG that will be > 32˚F under snow load(lower lite is over an occupied space that maybe heated), substitute an equivalent mono-lithic glass thickness for tU from Table A.3.)Obtain percent of design load carried byloaded lite % tL from Table A.1.* Calculate percent of design load carried by inner lite % tU (% tU = 100 - percent of design load carried by loaded lite % tL).**

Step 5 Calculate portions of design load carried byeach lite (percents from Step 4 x design load).Divide each of these loads by 1 (AN), 2 (HS), or 4 (FT) and by time factors 1.2 (AN), 1.6 (HS),1.8 (FT) for wind, or 0.6 (AN), 0.8 (HS), or 0.9 (FT) for snow, as appropriate. The results aremodified design loads for each lite: LtL and LtU.(Note: if load combinations must be considered, per-form Step 5 on both wind load and snow load, andadd the modified design loads for each liteaccording to the load combination formula.)

Step 6 Find appropriate glass strength charts for tL andtU in the Appendix (Charts A.1-A.12). For eachthickness, draw a vertical line from “L” and ahorizontal line from “W”; the intersection ofthese lines represents the strengths of the thick-nesses tL and tU (in kPa) for the trial designdefined in Step 3. (Interpolation between loadlines along a radial line from the chart originmay be necessary.)

Step 7 If the strengths of the trial thicknesses tL and tU

are larger than the modified design loads LtL

and LtU, the design is acceptable. If either of theindividual glass strengths is smaller than the corresponding modified design load, or if one or both of the glass strengths are much largerthan the corresponding modified design loads,an alternate design is indicated. Modify glassthicknesses and/or glass types in the trial designand repeat the process beginning with Step 3 (if thicknesses are changed) or with Step 5 ifglass types (only) are changed. Deflections maybe found using Procedure 3.

* Load share factors in Table A.1 were obtained from Reference 1.2.ASTM E1300-97 contains an alternate method for calculating loadsharing. If the ASTM E1300-97 procedure must be followed whenlaminated glass is employed in an asymmetrical IG unit, use theprocess detailed therein.

** ASTM E1300-97 does not recognize the equivalency between monolithic and laminated glass under wind and snow loads.


13

PROCEDURE 3: Deflection CalculationsThe model building codes contain no requirements thatlimit deflections in architectural glazing. ASTM StandardE1300-97 offers no recommendations regarding accept-able deflections. Dashed lines in the glass thicknessselection charts (Charts A.1-A.12 in Appendix) indicateloads and plate geometries for which the maximum lat-eral deflection of the glass exceeds 3/4-inch (19 mm).Industry practice varies, but limits on deflection oftenrelate to the perceived deflection of glass lites underload. Deflections on the order of the thickness of thelite are perceptible, especially for windows under windload. Since there are no specific building code limita-tions for deflections and guidelines for allowable deflec-tions in glass lites are stated only in general terms, thereis little need to obtain deflections with great accuracy.

Charts A.13a-A.13i (Appendix) contain approximations,for each thickness designation, of the deflections of 4-side, simply supported glass lites subjected to uniformlateral loads (wind and/or snow). Enter a graph for theappropriate glass thickness from the top (in.) or bottom(mm) with the width (smallest dimension) of the lite.Move vertically to a load line (psf or kPa) for the appro-priate aspect ratio (L÷W). Load lines may be drawn foraspect ratios between 1:1 and 2:1 by interpolating usingthe loads shown. Load lines for other loads may bedrawn by interpolating between load lines for a specificaspect ratio. Use of 2:1 load lines for aspect ratios above2:1 provides acceptable accuracy. Deflections in IG unitsare found by using the apportioned load acting on onelite (see Procedures 1 and 2). LAG unit defections are thesame as deflections of monolithic plates with the samethickness designations. Deflections of “warm” LAG litesin IG units under long-term (snow) load are found byusing the equivalent monolithic thicknesses specified inTable A.3 (Appendix).

The chart for deflections in 1/4-inch (6 mm) glass platesis presented below. Illustrated examples are included.

Example 1:34 x 34 in. (864 x 864 mm) lite, 40 psf (1.9 kPa)Center Deflection = 0.15 in. (3.8 mm)

Example 2:34 x 68 in. (864 x 1,728 mm) lite, 40 psf (1.9 kPa)Center Deflection = 0.32 in. (8.1 mm)

Example 3:34 x 51 in. (864 x 1,295 mm) lite, 40 psf (1.9 kPa)Center Deflection = 0.22 in. (5.6 mm)

1

FIGURE 4 Deflection Calculations Chart (6 mm)

0.3

12

0.1

10

1416

60 65 70 80

1,400 1,600 1,800 2,000

18

0.4

20 0.8

0.6

3

75

0.2

0.7

4

6

8

1,2001,000800600510

20 25 30 4035 45 50 55

0.5

Aspect Ratio 1

Aspect Ratio 2

20 psf (1 kPa)40 psf (2 kPa)

80 psf (4 kPa)

20 psf (1 kPa)4


Example 2

Example 3

Example 1

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

14

EXAMPLESFind the required lite thickness for a symmetri-cal LAG unit 30 x 90 inches in size that must

carry a wind load of 100 psf. (Aspect ratio = 3;Comprehensive Design Procedure 1, page 13, must be used.)

Step 1 3-second wind load = 100 psf.

Step 2 L = 90 inches, W = 30 inches; aspect ratio L ÷ W = 3. (Simple Design Procedure, page 6 is limited to aspect ratios ≤ 2.)

Step 3 For AN LAG: 100 ÷ 1 = 100 psf (4.8 kPa) For HS LAG: 100 ÷ 2 = 50 psf (2.4 kPa)For FT LAG: 100 ÷ 4 = 25 psf (1.2 kPa)[strength factors]

Step 4 For AN LAG: 100 ÷ 1.2 = 83 psf (4.0 kPa)For HS LAG: 50 ÷ 1.6 = 31 psf (1.5 kPa)For FT LAG: 25 ÷ 1.8 = 14 psf (0.8 kPa)[time factors]

Step 5 From Charts A.1-A.12:AN LAG thickness = 3/8 inch (10 mm)HS LAG thickness = 1/4 inch (6 mm)FT LAG thickness = 3/16 inch (5 mm)

(Note: 5/32-inch FT monolithic is also OK, but is not available in LAG.)

Using ASTM E1300-97: (Table 1)AN LAG: 100 ÷ 0.75 = 133 psf (6.4 kPa); t = 1/2 inch (12 mm)HS LAG: 100 ÷ 1.5 = 67 psf (3.2 kPa); t = 3/8 inch (10 mm)FT LAG: 100 ÷ 3.0 = 33 psf (1.6 kPa); t = 1/4 inch (6 mm)

100 psf

t

75 psf

tL

tU

1


FIGURE 5 Symmetrical Laminated Glass

FIGURE 6 Laminated Insulating Glass Unit

15

Design an IG unit with an outer monolithic fullytempered glass lite and an inner laminated glass

lite for a 60 x 80 inch opening. Snow load (acting normalto surface of glass) is 75 psf. The IG unit is supported onfour sides and is located over a heated occupied space.(Asymmetrical IG design and heated occupied space;hence, Comprehensive Design Procedure 2 for asymmet-rical IG units, page 12, must be used.)

Step 1 Design load = 75 psf (snow) acting normal tosurface of glass.

Step 2 Opening dimensions: L = 80 inches, W = 60 inches.

Step 3 Trial design: tL (loaded lite) = 1/4 inch FT; tU

(other lite) = 5/16 inch AN LAG.

Step 4 From Table A.3: equivalent monolithic glass thicknessfor 5/16 inch LAG lite at room temperature tU = 1/4 inchFrom Table A.1: W/tL=60/0.25=240 tU/tL=0.25/0.25=1.0% of design load carried by loaded lite = 50% of design load carried by unloaded lite(100-50) = 50

Step 5 Outer lite tL carries 75 x 0.50 = 38 psf.Inner lite tU carries 75 x 0.50 = 38 psf.Modified design load for tL (outer lite) = 38 ÷ 4 ÷ 0.9 = 11 psf.Modified design load for tU (inner lite) = 38 ÷ 1 ÷ 0.6 = 63 psf.

Step 6 From Chart A.6 (1/4 inch): strength tL = 26 psf(>11 psf, OK).From Chart A.6 (1/4 inch): strength tU = 26 psf(<63 psf, not acceptable).

Step 7 Change glass type (only) for tU (inner lite) toHS; return to Step 5 (Note: since thicknesseshave not changed, load share factors areunchanged.)Modified design load for tU (inner lite) =38 ÷ 2 ÷ 0.8 = 24 psf.From Chart A.6 (1/4 inch): strength tU = 26 psf (> 24 psf, OK).

Notes: A HS 1/4-inch outer lite (modified design load 38÷2÷0.8=24 psf) is also acceptable.A thinner FT outer lite may be acceptable; select alternate tL andrepeat from Step 3.If occupied space may not be heated, check design with lowerLAG lite acting as monolithic.

PROCEDURE 4 – SPECIAL CASESSpecial Case 1: LAG with Different Ply Thicknesses

(same glass type)

LAG fabricated with plies that are the same glass typebut with different ply thicknesses will act as a mono-lithic plate with a total thickness equal to the sum ofthe ply thicknesses, when subjected to wind or snowloads. This conclusion may be inferred from the exten-sive research on the behavior of symmetrical LAGreported in Section 3. Should LAG with the same glasstype but different ply thicknesses have to be treated as“layered” (a design condition that will not occur often),the analysis becomes mathematically complex. For sim-plicity, bending only behavior is assumed (membranebehavior is ignored) and each ply will assume a share ofapplied load in proportion to the cube of its thickness(see Example 1, next page). The load assumed by thethicker ply will always produce larger stresses in thethicker ply than the load assumed by the thinner plywill produce in the thinner ply. Hence, if the thicker ply can carry its share of the proportioned load, thedesign is satisfactory.

Special Case 2: LAG with Different Glass Types

This special design condition may occur when a combi-nation of two plies of AN, HS, or FT glass is employed.The procedures outlined below apply to LAG with athicker ply that is less than two times the thickness ofthe thinner ply.

■ If the stronger ply is placed in tension and the unitis not elevated in temperature, the unit will behaveas a monolithic plate with a total thickness equal tothe sum of the ply thickness. Unit strength is deter-mined by considering the monolithic plate to bemade of the stronger type of glass (see Example 2,next page).

■ If the stronger ply is placed in tension and theunit is at an elevated temperature, the strength of the unit is equal to the strength of the strongerply, acting alone (see Example 2, next page).

■ Independent of temperature, if the stronger ply is placed in compression, the strength of the unitis equal to the strength of the ply in compression,as if it were acting alone (see Example 3, next page).

2

1

16

EXAMPLES (Special Cases) Determine the strength of a 4 foot x 5 foot ANLAG unit (4-side support) composed of 1/8-inch

and 1/4-inch plies (a) at room temperature and (b) atelevated temperature:

(a) At room temperature (<100˚F) the LAG unit willbehave under uniform load as a 3/8-inch monolithicglass plate. From Window Glass Design Chart (page 7),3/8-inch, 20-ft2, AN plate with AR = 1.25 (interpolatelinearly between 1:1 and 2:1 lines): 60-second strengthis 72 psf.

(b) The LAG unit at elevated temperature (>100˚F) willbehave under uniform load as a “layered” systemwith 1/8-inch and 1/4-inch plies. The plies will shareload as follows:1/8-inch ply - 0.1253/(0.1253 + 0.253) = 11%1/4-inch ply - 0.253/(0.1253 + 0.253) = 89%

The strength of a 1/4-inch AN monolithic glass plate (20 ft2, AR 1.25, 4-side support) is 38 psf (Window Glass Design Chart, page 7). The 60-second strength of the layered system is 38 ÷ 0.89 = 42 psf (thicker ply controls).

Determine the strength of a 4 foot x 5 foot AN LAG unit (4-side support) with an AN

1/8-inch ply and a HS 1/4-inch ply, with the HS 1/4 plyin tension (a) at room temperature and (b) at elevatedtemperature:

(a) At room temperature and below (<100˚F), the 60-second strength is equal to the strength of an HS 3/8-inch monolithic plate:72 psf x 2 = 144 psf (see Example 1a, above).

(b) At elevated temperature (>100˚F) the 60-secondstrength is the same as an HS 1/4-inch plate: 38 psf x 2 = 76 psf (see Example 1b, above).

Determine the strength of a 4 foot x 5 foot LAGunit (4-side support) with an AN 1/8-inch ply

and an HS 1/4-inch ply, with the HS 1/4-inch ply incompression (a) at room temperature and (b) at elevatedtemperature.

The strength of the LAG unit at all temperatures is equalto the strength of the HS 1/4-inch ply, acting alone: 76 psf (see Example 2b, above). Note: the 1/8-inch AN plythat is in tension may fail under a load equal to the strengthof the 1/4-inch HS ply in compression.

Compression Tension

Compression Tension

12

3

FIGURE 7b Laminate Responding as Layers


FIGURE 7a Laminate Acting as Monolithic

FIGURE 8a Strength – Room Temperature

FIGURE 8b Strength – Elevated Temperature

17

DESIGNS FOR WINDBORNE DEBRISGlazed openings in buildings located at sites exposed to windborne debris during extreme windstorms shouldbe designed for possible debris impacts. In some areas,designs for windborne debris are mandatory, while inother areas designs for windborne debris are required if the building is not designed for full internal pressure.In many other situations (e.g., urban areas where wind-borne debris may be generated from adjacent buildingsand the urban environment), designing for windbornedebris is voluntary, but prudent.

Debris impact requirements in the South FloridaBuilding Code (SFBC, Reference 1.3) apply in Dade andBroward Counties of Florida. Provisions of SBCCI TestStandard for Determining Impact Resistance FromWindborne Debris, SSTD 12-97 (Reference 1.4), applyin Palm Beach County, and some municipalities withinthe county, in Florida. Texas Department of InsuranceStandard TDI 1-98, Test for Impact and Cyclic WindPressure Resistance of Impact Protective Systems andExterior Opening Systems, applies in coastal countiesof Texas, seaward of the Intracoastal Waterway(Reference 1.5).

ASTM E1886-97 Standard Test Method for Performanceof Exterior Windows, Curtain Walls, Doors and StormShutters Impacted by Missile(s) and Exposed to CyclicPressure Differentials (Reference 1.6) and its compan-ion specification (ASTM E1996-99) can be specified byarchitects and building owners.

Consideration of windborne debris as an alternative to designing for full internal pressures is required inhurricane-prone regions by ASCE Standard 7-98Minimum Design Loads for Buildings and OtherStructures (Reference 1.7) and the 1996 BOCANational Building Code (Reference 1.8).

The origins of these code requirements, test standardsand test methods are discussed in Section 4.

The procedure for designing for windborne debris is as follows:

1 Determine if consideration of windborne debris ismandatory, an alternative to designing for internalpressure, voluntary (prudent), or not needed (see Table 2 for guidance).

2 Establish appropriate debris impact criteria (see Table 3 for guidance).

3 Select glazing product or design concept that meetsdebris impact criteria (see Table 4 for guidance).

4 Qualify concept, design or product for use (see Table 6 for guidance).

1

18

TABLE 2 Requirements for Windborne DebrisRequirement Geographic Locations Comment/ReferenceMandatory Dade and Broward Counties of Florida; Palm Beach County, Dade and Broward Counties: South Florida

Florida (outside of municipalities); some Palm Beach County, Building Code; Palm Beach County: SSTD 12-Florida municipalities; residential construction in coastal 97; other Florida cities: contact localcounties of Texas, seaward of Intracoastal Waterway (to building official; coastal counties of Texas,obtain insurance through Texas Windstorm Insurance seaward of Intracoastal Waterway: TDI 1-98.Association); Areas defined in ASCE 7-98 and 1996 BOCANational Building Code.

Alternative to Areas defined in ASCE 7-98 and 1996 BOCA National See Figure 9 for areas requiring designs forinternal pressure Building Code. debris impact or for full internal pressure.

Voluntary Urban and suburban areas with potentials for windborne Owner/designer can cite ASTM E1886-97,debris in the form of roof gravel, roof tile, shingles, fascia, SSTD 12-97, South Florida Building Code,mechanical equipment and other debris from adjacent roof TDI 1-98, or can specify site specific criteria.tops, buildings, and the general environment.

Not needed Open suburban and rural sites with no adjacent buildings Consider future development adjacent to site.or other debris sources.

Areas with windspeed 110 mph (49 kph)or greater

FIGURE 9 Areas Requiring Consideration of Debris Impact (ASCE 7-98 and 1996 BOCA Basic Building Code)


19

TABLE 3 Establish Debris Impact CriteriaRequirement Criteria CommentSouth Florida Building Below 30 feet: 2 x 4 timber weighing 9 lbs. impacting end-on See Reference 1.3 for specific Code, Section 2315 (Impact at 50 ft./sec. (two per specimen). test requirements contained Tests for Windborne Debris); Above 30 feet: 2 gm rocks impacting at 80 ft./sec. (30 per in South Florida Building Code;Dade County Protocols specimen). contact Dade County Office of PA 201-94 (Impact Test Pressure cycles: each of above impacts followed by 9000 cycles Code Compliance or a Dade County Procedures) and PA 203-94 of pressure representing hurricane wind gusts. certified lab for test protocols.(Cyclic Wind PressureLoading)

SSTD 12-97: SBCCI Test Large missile impact test: 2 x 4 timbers impacting “end on” See Reference 1.4 for specific test Standard for Determining (Chapter 4): protocols contained in SSTD 12-97.Impact Resistance from windspeed* ≥ 110 – 9 lbs. at 50 fps Windborne Debris 100 < windspeed < 110 – 8 lbs. at 40 fps

90 < windspeed ≤ 100 – 4 lbs. at 40 fpsImpact each of three specimens twice (center and corner)or each of six specimens once (three center, three corner).

Small missile impact test: 2 gm steel balls impacting at 130 ft./sec.(Chapter 5):

Each of three specimens receives 30 impacts in three groupsof 10 (center, corner and center of long dimension).

Pressure cycles: 9000 cycles.Acceptance: Three specimens from each group of three shallpass the test.* windspeeds are fastest mile design windspeeds in mph

TDI 1-98: Test for Impact Large missile impact test: 2 x 4 weighing 9 lbs. impacting “end See Reference 1.5 for specific test and Cyclic Wind Pressure on” at 50 ft./sec.: protocols contained in TDI 1-98.Resistance of Impact Impact each of three specimens twice (center and corner) or Protective Systems and each of six specimens once (three center, three corner).Exterior Opening Systems Small missile impact test: 2 gm steel ball impacting at 130 ft./sec.:

Each of three specimens receives 30 impacts in three groups of 10 (center corner and center of long dimension).

Pressure cycles: 9000 cycles.Acceptance: three specimens from each group of three shall pass the test.

ASTM E1886-97: Large Missile Impact Test: 2 x 4 weighing 4.5 to 15 lbs. impacting See Reference 1.6 for specific Performance of Exterior between 0.10 and 0.55 of basic wind speed (number, size and test protocols contained in Windows, Curtainwalls, impact speed specified by user). ASTM E1886-97.Doors and Storm Shutters Small Missile Impact Test: solid steel ball having a mass of 2 gmImpacted by Missiles(s) and impacting between 0.40 and 0.75 of basic wind speed (numberExposed to Cyclic Pressure and impact speed specified by user). (Note: Companion Differentials specification to ASTM E-1886 is available as ASTM E1996-99.)

ASCE 7-98, Table 6-4: “In hurricane-prone regions (V ≥ 110 mph; see Fig. 9) glazed See Section 4 for discussion of Internal Pressure Coefficients openings in lower 60 ft not specifically designed to resist the effects of internal pressure for Buildings, GCpi windborne debris or are not specifically protected from windborne and advantages of debris impact

debris impact” must use internal pressure coefficient GCpi = 0.8 protection.for partially enclosed buildings.” (from Reference 1.7)

1996 BOCA National “Openings … which are likely to be breached by windborne See Section 4 for discussion of the Building Code, projectiles where the basic wind speed is 110 mph or greater” effects of internal pressure and Table 1611.7(6): Internal (see Fig. 9) must use internal pressure coefficient for partially advantages of debris impact Pressure Coefficients enclosed buildings. (from Reference 1.8) protection.for Buildings, Note e

Voluntary Site specific conditions may warrant large missile and/or small See Section 4 for conditions that missile impact tests: urban areas with gravel and debris on may warrant consideration of adjacent roof tops, urban and suburban areas with glass above debris impact, design examples, walkways, and spaces occupied by people. and references.

1

20

* All missile impact standards and codes include pressure cycles (see Table 17).

Notes:1. Glass shall be designed to meet ASCE-7 wind load requirements.2. Use plies with different glass types to obtain differential break

patterns.3. Glass bite minimum 1/2 inch.4. Use structural wet seal or high adhesion glazing tape.

TABLE 4 Select Glazing Concept or ProductImpact Requirement Glazing Concepts ReferencesLarge missile test in South Laminated glass with 0.090 inch or thicker interlayer and silicone See Figure 10 and Sections 2 and 3Florida Building Code, anchor detail (Impact Strength)Section 2315 and in SSTD 12-97, Chapter 4

Small missile test in South ■ ”Sacrificial ply” concept using laminated glass with 0.060 in. See Figure 11 and Sections 2 and 3Florida Building Code, interlayer (steel ball) or 0.030 in. interlayer (rock) in dry glazed (Impact Strength)Section 2315 and in SSTD system -

■ Laminated glass and silicone anchor detail (single lite)12-97, Chapter 5 ■ IG unit with laminated glass outer lite

Large debris (general); site ■ Single lites: silicone anchored laminated glass units with See Table 5 and Sections 2 and 3specific impact criteria 0.090 in. (minimum) interlayer (Impact Strength)developed by architect or ■ IG Units: one or more laminated glass units with 0.090 in.glazing consultant (minimum) interlayer

Small debris (general); site ■ Single lites: laminated glass using “sacrificial ply” concept or See Figure 12, Sections 2 and 3specific impact criteria “anchored lite” concept with 0.060 in. (minimum) interlayer (Impact Strength), and Section 4developed by architect or ■ IG units: both lites monolithic or outer lite laminated glass glazing consultant

TABLE 5 LAG Constructions That Meet Missile Impact Standards and Codes

Standard or Code LAG ConstructionSFBC Small Missile* Glass/0.030 in. Saflex/Glass

SSTD12-94,97 Small Missile Glass/0.060 in. Saflex/Glass

ASTM E1996-99 Small Missile Glass/0.060 in. Saflex/Glass

TDI 1-98 Small Missile Glass/0.060 in. Saflex/Glass

SFBC Large Missile Glass/0.090 in. Saflex/Glass

SSTD12-94,97 Large Missile Glass/0.090 in. Saflex/Glass

TDI 1-98 Large Missile Glass/0.090 in. Saflex/Glass

ASTM E1996-99 Large Missile Glass/0.090 in. Saflex/Glass

FIGURE 10 Glazing by Construction Glass Industries Inc. (approved by Dade County for Large Missile Impact)


21

SacrificialOuter Ply

(AN, HS, FT, CT)

Saflex Interlayer

LaminatedGlass With

Saflex Interlayer

Gasket

Heat Strengthenedor Fully Tempered Inner Ply

Saflex InterlayerStructural

Anchor Bead

3/8"(10 mm)

3/16"(5 mm)

3.0"

(75

mm

)

3/4"

(19

mm

)

TABLE 6 Qualify Concept or Product for UseImpact Requirement Qualification ProcedureMandatory Test at certified Dade County (Florida) laboratory, listed SBCCI laboratory, or listed TDI

laboratory in accordance with prescribed test protocols (SFBC, SSTD 12-97, TDI 1-98), or use “approved” product listed by Dade County Office of Code Compliance(www.buildingcodeonline.com).

Selected as alternative to internal pressure Use test procedures or products approved by a jurisdiction with mandatory impactrequirements (e.g., SFBC); test according to SSTD 12-97, TDI 1-98 or ASTM E1886-97;or use designs accepted as “standard of practice.”

Voluntary Use products approved by a jurisdiction with mandatory impact requirements, testusing protocols appropriate for specific design condition, or use designs accepted as“standard of practice.”

FIGURE 11 Glazing Detail Passing Small MissileImpact Test (Sacrificial Ply Concept)

FIGURE 12 Glazing Detail for Small Missile Impact(Non-hurricane Region; Reference 1.9)

1

22

ADDITIONAL DESIGN REQUIREMENTSOnce a glazing product has been designed for wind,snow or some combination of these common designloads, it may be necessary to consider additional designrequirements. In some design situations earthquakes,human impact, human loads, hail and special require-ments for overhead glazing must be addressed. Theinformation presented below will assist the designer inmeeting these additional design requirements.

EARTHQUAKESDesign – The response of buildings to earthquakes hasbeen studied extensively. Earthquake engineers candefine, in very precise terms, how the structural frameof a building moves during an earthquake. “Interstorydrift” (displacement of the top of a story relative to thebottom of the story) can be defined for a specific build-ing in a design earthquake. It is common practice tosimply provide enough clearance between glass edgesand the supporting frame to accommodate the inter-story drift. Design objectives for earthquakes are (1) toprevent breakage and (2) if glass breaks, prevent it fromfalling out. LAG exhibits superior performance in meet-ing the second design objective.

Tests – There is only very limited guidance available tothe designer who wishes to test the behavior of a glazingsystem under earthquake motions. An informal test procedure imposes, through the application of “static”forces, a prescribed interstory drift on a full-scale “mock-up” of an architectural glazing system. This test evaluatesthe ability of the glazing system to accommodate theinterstory drift without engaging the glass in a way thatwill produce breakage. While reasonably effective, thisstatic test does not replicate the multi-cycle, dynamicmotion induced by an earthquake. Further, this informalstatic test, while commonly prescribed as a component ofmock-up test regimes, is not defined in a formal standardor in a building code.

Research – Solutia has joined the U.S. National ScienceFoundation in developing methods to evaluate architec-tural glazing systems under earthquake motions. TheBuilding Envelope Research Laboratory (BERL) at theUniversity of Missouri-Rolla has conducted extensivetests to evaluate glazing system performance in earth-quakes. Full-scale architectural glazing systems havebeen subjected to dynamic “racking” that simulates

motions that can be experienced by buildings in earth-quakes. Results of this research have produced a pro-posed standard method of test (Reference 1.10) andcomparisons of seismic performance of architecturalglazing systems (Reference 1.11).

Proposed Standard Test Method – A format for a stan-dard test method is offered by Behr, et al. (Reference 1.11).A “crescendo test” imposes a steady increase of cyclic driftamplitudes. Interstory drift magnitudes are related to serviceability limit states (glass contact with frame) and ultimate limit states (glass fallout). The crescendo testconsists of a continuous series of alternating “ramp-up”and “constant-amplitude” intervals, each comprised offour sinusoidal cycles at a frequency of 0.8 Hz. Each driftamplitude step is ± 0.25 inch. The number of cycles at eachstep and the test frequency were selected to be reasonablerepresentations of drift-time histories that could occur inbuilding envelope wall systems under seismic loadings.

Preliminary Test Results – In a series of tests using theproposed test method, LAG exhibited consistently largerultimate limit state (glass fallout) drift amplitudes thanmonolithic glass and PET film coated monolithic glass(AN, HS, and FT). In other tests, heat treatment (HS andFT) only marginally increased drift amplitudes associ-ated with breakage. Structurally glazed systems per-formed well in earthquake tests.

HUMAN IMPACTIndustry standard ANSI Z97.1, Safety PerformanceSpecifications and Methods of Test for Safety GlazingMaterial Used in Buildings (Reference 1.12) and federalstandard 16 CFR 1201, Safety Standard for ArchitecturalGlazing Materials (Reference 1.13), contain provisions forarchitectural glazing materials that can be “broken byhuman contact.” Where architectural glazing can besubjected to human contact, these additional provisionsmay apply. Generally, these glazing products are doors,windows adjacent to sidewalks or passageways (with sillsnear floor level), side lights, and openings that may bemistaken as passageways.

Note that these safety glazing standards do not apply tosloped glazing and skylights (overhead glazing) unlessthese components can be broken by human contact. Alsonote that glazing products that meet the safety glazingstandards do not necessarily qualify for use in sloped glaz-ing and skylights. (See Overhead Glazing, next page, formodel code provisions for Sloped Glazing and Skylights.)


23

HUMAN LOADSGlass can be designed to minimize the risk of breakageor fallout under human loads.

Overhead Glazing – Overhead glazing should not be exposed to the weight of a person and should be designed to discourage people from walking on glass surfaces. If necessary, the ability of a lite in an over-head glazing unit to withstand human loads can be checked using the equation for a concentrated load, as shown below.

Glass Floors – The equations below may be used to design glass floors (walking surface of floors, land- ings, stairwells, and similar locations) for human and other loads. The design should be based on the load that produces the largest stresses from the following equations.

■ Uniformly distributed load: 2Fu + D ≤ Ffa x c2 x 0.67

■ Concentrated load: (8Fc/A) + D ≤ Ffa x c2 x 0.67

■ Actual load: Fa + D ≤ Ffa x c2 x 0.67

where:Fa = actual intended use load (psf);

double for dynamic applications

Fu = uniformly distributed load (psf),from building code

D = glass dead load (psf) = 13 tg

tg = total glass thickness (inches)

Fc = concentrated load (lbs.), frombuilding code

c2 = glass type factor (see Table 8)

Ffa = maximum allowable load on glass(from Charts A.1-A.12)

A = area of rectangular glass (sq. ft.)

* Use lower value for L/W ≥ 2 or W/t ≤ 150; use higher value for all other cases (L = long dimension, W = short dimension, t = lite thickness); factors apply to two ply laminates only.

LAG should have a minimum of three plies and shouldbe capable of supporting the total design load with anyone ply broken.

Surface damage caused by people or by objects placedon glass can significantly reduce the strength of glass,subjecting it to breakage under subsequent loads.

HAIL IMPACTSSloped glazing, skylights and some vertical window systems may be subjected to impact from hail. Fullytempered (FT) glass is more resistant to hail impact than annealed glass. Tests at Texas Tech University have shown that most hailstones will not break 6 mm(1/4 inch) FT glass. At terminal velocities (maximumspeeds attained by a falling hailstone) and higher, “iceballs” representing hailstones up to 75 mm (3 inches) in diameter shattered themselves and did not break 1/4-inch FT glass. Hail may break FT glass in thinnerthicknesses and all thickness of other types of glass (AN and HS).

Field experience and laboratory tests have shown thatwhen laminated architectural glass (LAG) is broken byhail impacts, only the outer ply breaks. Hence, AN, HS

TABLE 7 Safety Glazing Requirements – Consumer Products Safety CommissionCategory I Category II

Definition 9 sq. ft. or less, except patio doors, shower Greater than 9 sq. ft. and patio doors,and tub enclosures shower and tub enclosures of any size

Test Requirement* Break safely at 150 ft.-lb. impact Break safely at 400 ft.-lb. impact

Test Standard CPSC 16 CFR 1201 Category I or equivalent CPSC 16 CFR 1201 Category II or equivalentmodel code standard model code standard

Complying Laminated Glass Two-ply with 0.015 in. plastic interlayer or greater Two-ply with 0.030 in. plastic interlayer or greaterWith Saflex® Interlayer

TABLE 8 c2 Factors for Glass Floors (Single Glass)AN 0.6

HS 1.6

FT 3.6

LAG AN 0.3/0.45*

LAG HS 0.8/1.2*

LAG FT 1.8/2.7*

* Category I certification requires the glazing withstand one 150 foot-pound impact, produced by impacting a 100-pound shot bag from a vertical height of 18 inches.Category II certification requires the glazing withstand one 400 foot-pound impact, produced by impacting a 100-pound shot bag from a vertical height of 48 inches.

1

24

and FT LAG are good choices for protection from hailimpact. Should breakage occur, it is important to havean unbroken inner ply (single thickness lite) or anunbroken inner lite (LAG inner lite in an IG unit) tohelp resist subsequent loads, to preserve the buildingenvelope and to prevent glass fragments from fallingfrom the opening.

OVERHEAD GLAZINGThe three model building codes (Standard, Uniformand Basic) define “overhead glazing” as glass that ispositioned over space that may be occupied by humans.These model codes, in effect, prescribe PVB laminatedglass for overhead glazing that is either a single lite orthe lower lite in an insulating glass unit. There areexceptions and refinements to this general requirement,as noted below (language in each model building code is similar).

Allowable Glazing Materials – Sloped Glazing shall beof any of the following materials, subject to the limita-tions specified below.

For single-layer glazing systems, the glazing material ofthe single light or layer shall be laminated glass with aminimum 30-mil polyvinyl butyral (or equivalent) inter-layer, wired glass, approved plastic materials (meetingspecial requirements), heat strengthened glass, or fullytempered glass.

For multiple-layer glazing systems, each light or layershall consist of any of the glazing materials specifiedabove.

Annealed glass may be used as specified withinExceptions 2 and 3 (below).

Screening – Heat-strengthened glass and fully temperedglass, when used in single-layer glazing systems, shallhave screens installed below glazing. The screens shall be capable of supporting the weight of the glass and shallbe substantially supported below and installed within 4 inches of the glass. They shall be constructed of a non-combustible material not thinner than 0.08 inch with a mesh not larger than 1 inch by 1 inch. In a corrosiveatmosphere, structurally equivalent noncorrosive screen

materials shall be used. Heat-strengthened glass, fully tem-pered glass and wired glass, when used in multiple-layerglazing systems as the bottom glass layer over the walkingsurface, shall be equipped with screening which complieswith the requirements for monolithic glazing systems.

Exceptions:1 Fully tempered glass may be installed without required

protective screens when located between interveningfloors at a slope of 30 degrees or less from the verticalplane if the highest point of the glass is 10 feet or lessabove the walking surface.

2 Allowable glazing material, including annealed glass,may be installed without required screens if the walk-ing surface or any other accessible area below the glazing material is permanently protected from fallingglass for a minimum horizontal distance equal totwice the height.

3 Allowable glazing material, including annealed glass,may be installed without screens in the sloped glazingsystems of commercial or detached greenhouses usedexclusively for growing plants and not intended for useby the public, provided the height of the greenhouseat the ridge does not exceed 20 feet above grade.

4 Screens need not be provided within individualdwelling units when fully tempered glass is used assingle glazing or in both panes of an insulating glassunit when all the following conditions are met:

(a) The area of each pane (single glass) or unit (insulating glass) shall not exceed 16 square feet.

(b) The highest point of the glass shall not be morethan 12 feet above any walking surface or otheraccessible area.

(c) The nominal thickness of each pane shall notexceed 3/16 inch.

5 Screens shall not be required for laminated glass hav-ing a minimum 0.015 inch polyvinyl butyral inter-layer within dwelling units. Such laminated glass shallnot exceed 16 square feet in area nor shall the highestpoint of the glass exceed 12 feet above any walkingsurface.

Structural Design Methods 1

25

ANNEALED GLASS STRENGTHThe fundamental strength of annealed (AN) glass is presented in 12 charts, one for each standard glassthickness, in ASTM E1300-97 (Reference 1.1). Thesestrengths are based upon a theoretical glass breakagemodel which relates the strength of AN glass to its sur-face condition. A conservative estimate of the “weath-ered” surface condition of in-service AN glass was usedin producing the charts. Since the strength of AN glassis dependent on both the time duration of loading andthe probability of glass breakage, the strengths presentedin the charts are referenced to a “60-second constantload” for an “8 per 1,000 probability of breakage.”

GLASS TYPE FACTORSStrengths obtained from the charts are multiplied by “glass type factors” to account for differences instrength (strength factors) and for time duration of loading (time factors). Glass type factors are applied to AN, heat strengthened (HS), and fully tempered (FT) glass, as well as to laminated architectural glass(LAG) and to insulating glass (IG).

Heat treatment produces large compressive stresses onthe surfaces of glass plates (see Figure 13a). For breakageto occur, stresses from loads such as wind and snowmust first overcome the “pre-stressed” surface conditionand then induce tensile stresses that are sufficientlylarge to produce fracture. As defined in ASTM C1048(Reference 2.1), initial surface compressive stresses of atleast 3,500 and 10,000 psi are produced in HS and FTglass, respectively. Strength factors of 2 for HS glass and 4 for FT glass are commonly applied to AN glassstrengths as strength factors for these types of glass.

Center in Tension

Surfaces in Compression

0.2 t Compression Zone

0.2 t Neutral Zone

0.2 t Tension Zone

0.2 t Neutral Zone

0.2 t Compression Zone

10,000 psi (min)

Basic Factors in Glass Strength 2section

FIGURE 13a Tempered Glass

FIGURE 13b Stress Distribution in Fully Tempered Glass

26

Laminated architectural glass (LAG) behaves likemonolithic glass with the same nominal thicknessunder short-term (wind) loads at room temperature (< 100˚F), and under long-term (snow) loads of 32˚F andlower. (This behavior was established through extensiveresearch reported in Section 3.) Hence, under wind andsnow load conditions with temperatures as notedabove,* the strength of LAG is the same as monolithicglass with the same nominal thickness (strength factor =1). Should a LAG lite experience long duration loadswhile the interlayer temperature is above 32˚F (e.g., thelower lite in an IG unit over a heated occupied spaceunder snow load), it is appropriate to treat the LAG liteas a “layered” system.

Insulating glass (IG) contains a sealed airspace thatresults in “load sharing” between lites. If the lites in anIG unit are the same type (AN, HS, FT), equal in thick-ness and relatively thin, the lites will share load equally.In these cases, therefore, a strength factor of 2 is appro-priate (i.e., the strength of an IG unit is twice thestrength of one lite). If the IG unit is not “symmetrical”(i.e., lites are different in thickness and/or glass type) or is “thick” (i.e., short dimension ÷ thickness of one lite ≤ 150), load sharing will not be equal. In these cases,determination of the strength of an IG unit becomesvery complex and involves the calculation of “loadshare factors.” Fortunately, most IG units employed inbuildings are symmetrical and thin; hence, the SimpleDesign Procedure (Section 1) uses a strength factor of 2.Design situations in which these conditions are not metare addressed in the Comprehensive Design Procedure(Section 1).

* Design wind loads usually occur during windstorms (e.g. hurricanesand thunderstorms) that are accompanied by clouds and rain or coldfronts. Hence, the ambient temperature and the temperature of LAGinterlayers is usually below 100˚F when design wind loads occur.

LOAD DURATIONGlass strength varies with the length of time that theload is applied (Figure 14).

In recognition of this phenomenon, 60-second glassstrengths may be adjusted by “time factors” to accountfor short-term (wind) loads and long-term (snow) loads.Recommended time factors that adjust 60-secondstrengths for time duration of load are listed below.

ASTM E1300-97ASTM E1300-97 does not recognize the equivalency ofmonolithic glass and LAG under the temperature andtime duration of loading conditions described above.This standard assigns strength factors for LAG that rangefrom 0.5 to 0.9, and assigns a strength factor of 1.8 tosymmetrical, thin IG units. Further, this standard over-looks the increase in glass strength under wind (3-secondduration) loads. Hence, glass strength factors and adjust-ments for load duration (time factors) that are containedin ASTM E1300-97 as glass type (GT) factors differ fromthose presented above. The Simple and ComprehensiveDesign Procedures presented in this Guide (Section 1)include provisions for utilizing alternate strength factorsand load duration factors (combined into GT factors) for users who must use ASTM E1300-97.

TABLE 9 Strength FactorsShort-term Long-term

Glass Type (wind, 3 sec.) (snow, 2 wk.)AN 1.2 0.6

HS 1.6 0.8

FT 1.8 0.9

0

5,000

1 second

Brea

king

Stre

ss (p

si)

Duration of Stress

10,000

15,000

Annealed Glass

1 hour 1 day 1 week 1 month

Basic Factors in Glass Strength

FIGURE 14 Effect of Load Duration on Glass Strength

27

IMPACT STRENGTHArchitectural glazing may be required to reject impactsfrom large objects such as 2x4 timbers and from smallobjects such as roof gravel. The South Florida BuildingCode (SFBC), SBCCI SSTD12-97 and TDI 1-98 (References1.3, 1.4 and 1.5) define impact criteria using these mis-siles for use in design under conditions involving extremewindstorms (see Section 1 and Section 4). A 2 x 4 timberrepresents large objects and steel balls or rocks representsmall objects that may occur in windstorms.

Glazing products respond to impacts from these objectsin three ways. First, single plates of monolithic glass ofvarious thicknesses and heat treatments have the capac-ity to resist breakage from a small missile as shownbelow. Note that steel balls traveling at 80 feet/second(as prescribed in the SFBC) and at 130 feet/second (asprescribed in SSTD12-97) can be expected to break allthicknesses and types of monolithic glass. It has beenfound in other tests that, while “hard” rocks (commonlyriver run gravel) are equivalent to steel balls, certaintypes of rocks traveling at 80 feet/second may not breaksome thicknesses of fully tempered glass. Testing withrocks of unspecified hardness is not recommended.

Second, LAG has the ability to accept impacts fromsmall missiles through breakage of the impacted (outer)ply while preserving the integrity of the inner ply. LAGallows designs for wind load using the strength of theinner ply (only) with the assumption that the outer plywill break but protect the inner ply from the initial andsubsequent impacts. Strengths of LAG acting in thiscapacity are shown in Table 11 (Reference 2.2).

These data suggest that LAG constructed with interlayers0.060 inch and thicker, and with heat treated glass lites3/16 inch and thicker, can be expected to perform under

the 80 feet/second small missile impact specified in theSFBC without breaking the inner ply. Inner ply breakagecan also be avoided by using thinner plies and/or thickerinterlayers. For example, LAG construction with 1/8 inchAN/0.060 inch interlayer/1/8 inch AN has performedwell in this application.

Finally, LAG can stop impacts from large objects repre-sented by the 2 x 4 timber. In this application, breakageof both plies is allowed, but penetration by the impact-ing timber is prevented. A relatively thick PVB interlayer(0.090 inch) may prevent penetration of the unit by the impacting object and holds broken glass particlestogether. The specific LAG constructions listed in Table 12are some of the successful configurations used to stop twoimpacts of the 9 lb 2 x 4 at 50 feet/second, one at thecenter of the lite and one within 6 inches of a corner,specified as the impacting missile in the SFBC, in SBCCISSTD 12-97, in ASTM E1996-99 and in TDI 1-98.

TABLE 10 Average Minimum Impact VelocityCausing Fracture

(2 gm steel ball)

t (in.) AN FT3/16 30 fps 65 fps

5/16 30 fps 65 fps

3/8 35 fps 60 fps

1/2 40 fps 50 fps

3/4 55 fps 55 fps

TABLE 11 Inner Ply Breakage Rates in LAG Under Impacts

Impacts from 2 gm Steel Balls at 117 ft/sec (80 mph) (outer ply/Saflex® interlayer/inner ply)

Glazing Construction Inner Ply (interlayer thickness, in.) Breakage Rate

3/16HS/0.060/3/16HS 0.0010

3/16FT/0.060/3/16FT 0.0066

3/16HS/0.090/1/4HS 0.0027

3/16HS/0.120/1/4HS 0.0010

TABLE 12 Impact Resistant LAG ConstructionsLAG Constructions That Can Arrest Without Penetration the 9 lb.

2 x 4 at 50 ft./sec. Specified in the SFBC, SSTD12-97, ASTM E1996-98 and TDI 1-98 (outer ply/Saflex® interlayer/inner ply)

Opening Size Glazing Construction (glass and(in.) interlayer thickness in inches)

44 5/8 x 92 1/4HS/.090/1/4HS

38 x 72 3/16HS/.090/3/16HS

37 3/8 x 50 1/4 3/16HS/.090/3/16FT

48 x 72 1/8AN/.090/1/8HS

37 x 63 1/8AN/.090/1/8HS

26 1/2 x 50 5/8 1/8AN/.090/1/8HS

48 x 60 1/8AN/.090/1/8AN

60 x 100 1/8AN/.090/1/8AN

2

28

RESEARCH SUMMARYA comprehensive series of research studies on laminatedarchitectural glass (LAG) has provided the technicalbasis for the design recommendations contained in thisGuide (References 1.10, 3.1, 4.9). LAG behavior was stud-ied under lateral pressures representing wind and snowloads, under impacts from several sizes of windbornedebris, and under conditions simulating dynamic earth-quake motions. The attributes of LAG were establishedin each study. Under lateral pressure, LAG acts likemonolithic glass of the same nominal thickness undershort-term (wind) loads when the temperature is below100˚F and under long-term (snow) loads when the tem-perature is 32˚F and below. Under impact from wind-borne debris (large and small missiles), broken LAG(both plies) tends to remain in the opening following

breakage. Further, small missile impacts may break onlythe outer ply, allowing the inner ply to remain integraland carry subsequent wind pressures. Under dynamicearthquake motions, broken LAG resists fallout at largerdrift amplitudes than monolithic glass and monolithicglass with PET film.

LATERAL PRESSURELayered and monolithic glass lites (See Figure 15) wereanalyzed theoretically using experimentally verifiedcomputer programs. In addition, tests to failure (glassfracture) of approximately 400 LAG lites were employedto confirm predicted performances. Test samples wereconstructed with annealed (AN), heat strengthened (HS)and fully tempered (FT) glass laminated with Saflex®

interlayer by Solutia.

Laminated Glass Behavior 3sectionFIGURE 15 Glass Plate Systems

Monolithic Laminated Layered

29

VERIFICATION OF COMPUTER PROGRAMSThe first research step involved theoretical developmentand experimental verification of computer programsthat describe monolithic and layered thin plate behav-ior. Verification was achieved for both monolithic and

layered systems. The extraordinarily good correlationsfor both stress and deflection (Reference 3.2) are sum-marized in Figures 16a-d. (Specimens were 60 x 90 x 1/4 inch; T - Theory; E - Experiment.)

2.0

0.50

Pressure (psi)

Max

imum

Stre

ss (k

si)

0.750.25

4.0

6.0

8.0

Corner

y

x

σ2

σ1

Center

ET

E T

σ2

σ1

2.0

0.50

Pressure (psi)

Max

imum

Stre

ss (k

si)

0.750.25

4.0

6.0

8.0 Corner

Center

E T

E

T

0.5

0.50

Pressure (psi)

Defle

ctio

n (in

.)

0.750.25

1.0

1.5 ET

0.5

0.50

Pressure (psi)

Defle

ctio

n (in

.)

0.750.25

1.0

1.5E

T

FIGURE 16a Monolithic Maximum Stress

FIGURE 16b Monolithic Deflection FIGURE 16d Layered Deflection

FIGURE 16c Layered Maximum Stress

Laminated Glass Behavior 3

30

LAMINATED GLASS BEHAVIORThe second research step compared the behavior of LAG to that of monolithic lites and layered lites. Non-destructive tests under uniform lateral pressures appliedlinearly with time to achieve 0.4 psi in 15 seconds wereaccomplished at temperatures ranging from 32˚F to 170˚F. Results of these tests (Reference 3.2) produced the conclusion that LAG behaves like monolithic glassunder short-term loads at room temperature and below(<100˚F). The temperature above which LAG begins tobehave like a layered system is not clear, but is about120˚F. (Specimens were 60 x 96 x 1/4 inch; see Figures17a and 17b).

TIME DURATION OF LOAD EFFECTSIn a third research step, the effects of time duration of load were studied. Sustained loads were applied in 5 seconds to a 60 x 90 x 1/4 inch LAG specimen at several temperatures and held constant for one hour(see Figure 18). Results of these tests provide additionalsupport for a conclusion that LAG behaves like mono-lithic glass under wind gusts (less than 3 seconds dura-tion) at temperatures below 100˚F (Figures 17a and 17b).

2.0

0.50

Pressure (psi)

Max

imum

Stre

ss (k

si)

0.25

4.0

6.0

0.500.25

8.0

Corner Center

LayeredMonolithic

170°F

120°F100°F

72°F32°F

LayeredMonolithic

170°F120°F

100°F

72°F32°F

0.5

0.50

Pressure (psi)

Defle

ctio

n (in

.)

0.25

1.0

1.5

0.75

Layered

Monolithic

170°F120°F

100°F72°F

1.0

1,000 3,500

0.2

0.4

0.6

0.8

51

Max

imum

Def

lect

ion

(in.)

Elapsed Time (sec.)10 100

0

Lateral Load – 0.2 psiConstant After t = 5 seconds

LaminatedLayered Unit

Monolithic

170°F120°F72°F

Laminated Glass Behavior

FIGURE 17a Maximum Stress

FIGURE 17b Deflection

FIGURE 18 Effects of Sustained Load:Maximum Deflection

31

INTERLAYER THICKNESSFurther research addressed the effects of interlayer thickness on the behavior of LAG under lateral pressure.Identical lites of LAG with 0.030 inch and 0.060 inchSaflex® interlayer thicknesses were tested at room tem-perature. The results (see Figures 19a and 19b) indicatethat only small (less than 5%) changes in stresses anddeflections occur as the interlayer thickness is changedfrom 0.030 inch to 0.060 inch (Reference 3.3).

FAILURE STRENGTHSSeveral series of tests to failure (glass fracture) have beenconducted using LAG specimens of various sizes andthicknesses, and containing different interlayer thick-nesses and glass heat treatments (Reference 3.4). Resultsof these tests confirm behaviors observed in the theoret-ical analyses and non-destructive tests described above.Annealed (AN) LAG lites with an 0.030 inch interlayerexhibit failure strengths similar to monolithic AN glasslites of the same nominal thickness at room tempera-ture, and AN LAG lites with thicker (0.090 inch) inter-layers exhibit much larger failure strengths (Reference3.5) (see Table 13). At elevated temperature (170˚F) ANLAG strengths drop to about 75% of comparably sizedmonolithic glass (see Table 14). Heat strengthened (HS)and fully tempered (FT) LAG lites were 3.2 and 5.0 timesas strong, respectively, as AN LAG lites. These tests sug-gest that HS and FT LAG lites have strength factors simi-lar to strength factors for HS and FT monolithic lites atroom temperature (see Table 15).

* LAG specimens were loaded to failure at the same loading rate as comparable monolithic glass specimens. Test temperatures 75˚F.

** LAG specimens were loaded to failure at the same loading rate as comparable monolithic glass specimens

** LAG interlayer thickness 0.030 in.

TABLE 13 Failure Strengths of AN Monolithic and LAG at Room Temperature*

AN LAG

Interlayer Thickness

Unit (inches) AN Monolithic 0.030 in. 0.090 in.60 x 96 x 1/4 63 psf 76 psf 144 psf

38 x 76 x 1/4 137 psf 135 psf 191 psf

66 x 66 x 1/4 107 psf 111 psf 141 psf

TABLE 14 Failure Strengths of AN Monolithic and LAG as a Function of Temperature*

AN LAG

Degrees F

Unit (inches)** AN Monolithic 75 120 17038 x 76 x 1/4 137 psf 135 psf 120 psf 101 psf

60 x 96 x 1/4 63 psf 76 psf – 46 psf

1.0

Lateral Pressure (psi)

Max

imum

Prin

cipal

Stre

ssNe

arCo

rner

(ksi)

0.5

1

1.5

2

3

4

5

6

7

8

9

10

02.0

Layered

MonolithicLaminated (0.030")Laminated (0.060")

1.0

Lateral Pressure (psi)

Max

imum

Def

lect

ion

(in.)

0.5

0.5

1.50

2.0

1.0

1.5

Monolithic(theoretical)

Laminated (0.060")Laminated (0.030")

Layered(theoretical)

Total Glass Thickness Is Equal for All Cases

3

FIGURE 19a Maximum Stress

FIGURE 19b Maximum Deflection

32

* LAG specimens were loaded to failure at room temperature and atthe same loading rate.

** LAG interlayer thickness 0.030 in.+ Average surface compression was 7,700 lbs./sq. in.

++ Average surface compression 13,000 lbs./sq. in.

IMPACT STRENGTHField evaluations of windborne debris in hurricanes,typhoons and other extreme windstorms have definedthe nature of objects that may impact architectural glaz-ing. These definitions of windborne debris have beencodified in standards and building codes. Impactingobjects have been placed into two categories: large mis-siles and small missiles. The class of large missiles is rep-resented by 2x4 timbers of several weights impacting atseveral velocities. The class of small missiles is repre-sented by roof gravel and is portrayed in tests by steelballs weighing 2 gm or hard rocks of comparableweight. Background information on the evolution ofmissile impact criteria is contained in Section 4.

Large missile impacts will break both plies of LAG. Theattributes of LAG that make it valuable under this typeof impact are its ability to resist penetration and its tendency to remain in the opening following breakage.LAG with 0.090 inch and thicker interlayers that issecured in the frame with a silicone anchor seal or high adhesion glazing tape can preserve the integrity of the building envelope under these impact conditions.All designs for large missile impact should be tested toimpact criteria similar to those outlined in ASTM E1886-97, TDI 1-98 or SSTD12-97 to ensure suitable performance.

Small missile impacts may break both plies or only theouter ply of LAG. If both plies are broken, a siliconeanchor seal or high adhesion glazing tape will assist inretaining the broken unit within its frame during subse-quent wind gusts. In many small missile impact envi-ronments, however, the small missile will break only theouter ply, leaving the inner ply intact with an ability toresist subsequent wind gusts. If the interlayer is rela-tively thick and the glass plies are heat treated, theprobability of breakage of the inner ply under specifiedimpact conditions can be very low (Table 16, Reference3.6). This concept provides a basis for designs in whichthe outer ply is “sacrificed” to small missile impacts andthe inner ply is able to carry design wind pressures. Inthese designs, the silicone anchor seal or high adhesiontape is not required, although it may be prudent toinclude one or the other for structural redundancy.Standard glazing practices are sufficient for LAG perfor-mance for small missile impact if the sacrificial ply concept is employed.

* All units have 2 plies of 3/16 in. glass.

TABLE 15 Failure Strengths of AN, HS and FT LAG*Unit (inches)** AN LAG HS LAG FT LAG38 x 76 x 1/4 135 psf 426 psf+ 691 psf++

TABLE 16 LAG Breakage Rates as a Function ofInterlayer Thickness and Heat TreatmentInner Ply Breakage Rates for 2 gm

Missile Impacting at 80 MPH (117 fps)Laminated Glass Interlayer BreakageConstruction* Thickness Rate (%)

3/8 HS 0.030 in. 54.0

7/16 AN 0.060 in. 5.4

7/16 HS 0.060 in. 4.2

7/16 FT 0.060 in. 0.7

Laminated Glass Behavior 3

33

The sustained, turbulent winds in hurricanes, typhoonsand other extreme windstorms carry large amounts ofdebris onto building facades, breaking windows andsubjecting the building interior to internal pressures,wind and rain. Concerns with occupant safety and withlarge insured losses to buildings have prompted changesto building codes in the U.S. The South Florida BuildingCode mandates protection of windows from windbornedebris. Provisions in ASCE 7-98 and the 1996 BOCANational Building Code require special designs forglazed openings in order to protect the building envelopefrom being breached during hurricanes or the buildingmust be designed for the effects of full internal pressure.

This section of the Guide summarizes experiences thatfostered the new design requirements, describes the hur-ricane (typhoon) environment, outlines the new impactcriteria and describes new products that have beendeveloped to protect buildings from windborne debris(Reference 4.1).

WINDSTORM EXPERIENCESArchitectural glazing in several tall buildings in Houston,Texas, was broken by windborne debris generated byHurricane Alicia (see Figure 20). Hurricane Andrew damaged facades in several major buildings in southFlorida (see Figure 21). Failures of cladding systems during hurricanes result in damage to buildings, loss of building contents, interruption of business, hazards to people and marred images for buildings that have sustained damage. Events over a 25-year period duringwhich architectural glazing in buildings was broken during hurricanes are summarized in Reference 4.2.Experiences with architectural glazing in HurricaneAndrew are summarized in Reference 4.3.

Windborne Debris 4section

FIGURE 20 Houston, Texas – Hurricane Alicia

FIGURE 21 Miami, Florida – Hurricane Andrew

34

HURRICANES AND TYPHOONSThe effects of winds in hurricanes and typhoons areespecially harsh (Reference 4.4). Turbulent winds canaffect a building for hours. These winds change slowlyin direction as the storm approaches and passes over a building (see Figure 22). Debris can be progressivelydislodged from adjacent structures, accelerated by

sustained winds and can impact all elevations on abuilding. Following impact, the building can be buffetedby sustained and cyclic wind pressures for hours beforethe storm moves away. Prior to 1992 this severe envi-ronment had not been recognized by building designers,building officials and glazing product manufacturers inthe United States.

Eye Wall

Wind Paths

Point A North

Windborne Debris

FIGURE 22 Hurricane/Typhoon Wind Field (a building at Point A will experience winds changing in direction from N to SE as the hurricane travels right to left)

35

THE NATURE OF WINDBORNE DEBRISIn extensive wind damage surveys conducted through-out the 1970s, a pattern became apparent that proved tobe common to all types of extreme wind events. Smalldebris, principally roof gravel, can be carried into all ele-vations of building facades at velocities sufficiently largeto break glass. Large debris, including framing timbersand roofing materials, can impact the building envelopenear ground level with sufficient force to penetrate wallcoverings and break windows (Reference 4.5). Researchhas defined the nature of both small and large debris inwindstorms.

Small Missiles – An analysis of the window damagingmechanism during windstorms in urban areas identifiedroof gravel as the principal form of small debris thatcauses damage to windows in the upper floors of high-rise buildings (Reference 4.6). Field surveys of typicalbuilt-up roofs (conventional “tar and gravel”) estab-lished the average roof gravel size as 0.6 gm, and anaverage large size of roof gravel as 5 gm. The SFBC, SSTD12-97, ASTM E1886-97 and TDI 1-98 have adopted 2 gmas the standard size small missile.

Large Missiles – In investigations of tornadoes, it wasconcluded that the most prevalent type of windbornedebris in residential areas is timber from wood framehouses (Reference 4.7). Individual timbers were observedto have broken windows, penetrated walls and roofs,and been impaled in the ground. Additional windborne timbers were attached together as parts of failed roofingsystems, timber trusses and timber walls. These observa-tions led to the selection of a 2 x 4 timber weighing 7 kg (15 pounds) as a representative object for use indefining impact criteria for tornado shelters in schoolsand residences (Reference 4.8). A 2 x 4 timber, 3.7 m (12 feet) in length, and travelling at 1/2 of the designwind speed was advanced as one of three “large” objectsrecommended for use in the design of lower elevationcladding on urban buildings (Reference 4.9). This recom-mendation was based upon research being conducted bythe nuclear industry on missile impact speeds in torna-does and other extreme windstorms. A list of large mis-siles for use in design is contained in Department ofEnergy Standard DOE-STD-1020-94 (Reference 4.10).The SFBC, SSTD 12-97, TDI 1-98 and ASTM E1886-97have adopted a 2 x 4 timber as the standard large missile.

THE BUILDING ENVELOPEThe building envelope must remain integral duringwindstorms. Breaching of the building envelope produces several harmful effects: internal pressure, exposure of occupants to wind and rain, damage tobuilding contents, additional debris in the wind stream,hazardous debris falling to the street, disrupted business,and a blemished image of the building. Windbornedebris has been established as a principal cause for thebreaching of the building envelope during hurricanes.Failure of windward wall cladding (windows and wallcoverings) or doors leads to an increase in pressureinside the building and can produce failure of the prin-cipal structural frame. As shown in Figure 23, internalpressures can effectively double forces acting to lift theroof and push side and leeward walls outward. Insuredlosses in both residential and commercial buildings areincreased significantly when the building envelope isbreached (Reference 4.11).

4

FIGURE 23 Breaching of the Building EnvelopeDoubles Forces

36

POST-BREAKAGE BEHAVIORThe post-breakage behavior of architectural glazing inurban high-rise buildings is important for two reasons.First, hazards to people on urban streets establishes theimportance of keeping broken particles of glass withinthe window opening should breakage occur. Second, theimportance of preserving the integrity of the buildingenvelope reinforces the benefit of keeping broken glassin the opening should debris induced breakage occur.Laminated architectural glass offers opportunities toachieve both objectives (keeping particles within theopening and preserving the integrity of the buildingenvelope) following breakage.

TEST PROTOCOLSUnderstandings of the hurricane environment, and theconcerns with public safety and property protection dis-cussed above, have produced test protocols for claddingdesigns. These protocols use missile impact, followed byapplication of a pressure spectrum, as a basis for qualify-ing architectural glazing system designs for hurricanesand typhoons. A test was devised for non hurricaneprone regions in which roof gravel weighing 2 gm ispropelled onto the window at a speed equal to thedesign wind speed for a specific building (Reference4.12). Following multiple impacts, the window system issubjected to a sequence of pressure cycles to test its abil-ity to remain in the opening following breakage. Thisprecedent led to similar test protocols that are employedin SBCCI Standard SSTD 12-97, the two editions of theSouth Florida Building Code, ASTM E1886-97 and TDI1-98 (see Table 17).

TABLE 17 Typical Standard for Windborne Debris Impact TestsLarge Missile Impact Test Three identical test specimens(for windows, doors, skylights, glazing and Missile is 2" x 4" timber weighing 9 lbs. (= 4.1 kg) shutters between grade and 30’ [=9.1m] Two impact points at 50 ft./sec.: one at center, one within 6" (=15.2 cm) of a corner.above grade) All three specimens must survive impacts without penetration before proceeding to

cyclic pressure loading.

Small Missile Impact Test Three identical test specimens(for windows, doors, skylights, glazing and Missile is steel ball or roof gravel weighing 2 g (= 0.07 ounces). shutters above grade and 30’ [=9.1m] 30 small missile impacts at 130 ft./sec.: 10 at center, 10 near long edge, 10 near corner.above grade) All three specimens must survive impacts without penetration before proceeding to

cyclic pressure loading.

Followed by:

Cyclic Pressure Inward-Acting Pressure Outward-Acting Pressure(applied to all three specimens following Range Cycles Range Cycleslarge or small missile impact tests: duration

0.2Pmax-0.5Pmax 3,500 0.3Pmax-1.0Pmax 50of each cycle is 1-3 seconds; all inward-acting0.0Pmax-0.6Pmax 300 0.5Pmax-0.8Pmax 1,050pressure cycles are applied first, followed by0.5Pmax-0.8Pmax 600 0.0Pmax-0.6Pmax 50outward-acting cycles)0.3Pmax-1.0Pmax 100 0.2Pmax-0.5Pmax 3,350

Pmax is design wind pressure (inward and outward) from the building code, basedon an unbreached building envelope.

Pass/Fail Criteria All three specimens must survive the missile impacts without penetration. If no tear or crack longer than 5" (=12.7 cm), or no opening through which a 3" (=7.6 cm) spherecan pass, has formed in any of the three specimens upon completion of the pressure cycles, they are deemed to have passed the test.

Windborne Debris

37

RESEARCH AND DEVELOPMENTThe glazing, door and shutter industries have developednew glazing products, cladding system designs, andexternal protective devices (shutters) in response to thenew code requirements and test criteria. Two principaldesign concepts that use LAG have evolved:

Silicone Anchored LAG - LAG is anchored to the win-dow frame with a silicone “seal.” In this concept, theglass (both plies) can break, under missile impact, yetremain integral and within the frame during pressurecycles that represent wind gusts following breakage (Figure 24).

Sacrificial Ply - LAG can reject small missile impacts(e.g., roof gravel) using a “sacrificial ply” principle. Theouter ply is allowed to break while the inner ply carriesthe design wind load (Figure 25).

LAMINATED ARCHITECTURAL GLASSThe demands of wind and impact resistant constructionhave identified LAG as the product of choice for theseapplications. Not only is LAG equivalent in strength to monolithic glass of the same nominal thickness, but also it accepts breakage through missile impact in ways which tend to retain it in the opening. Techno-logical advancements in the design of architectural glaz-ing for extreme wind, earthquake, and other hazardousdesign environments also continue to highlight LAG as the product of choice for passive building envelopeprotection.

ShimStructural Laminated Glass with Saflex PVB Interlayer

GasketPressure PlateCover

Saflex

Laminated Glass with Saflex

Interlayer

Gasket

Heat Strengthened or Fully Tempered Inner Ply

Sacrificial Outer Ply(AN, HS, FT, CT)

FIGURE 24 Silicone Anchored LAG

FIGURE 25 Sacrificial Ply LAG

4

38

SUMMARYThe Design Guide to the Structural Performance ofLaminated Architectural Glass (the Guide) is a state-of-the-art presentation. The Guide contains three major contri-butions to design practice:

1 a simple approach to the selection of glass thick-ness under wind and snow loads that applies tomost design conditions involving architecturalglazing (Section 1, Simple Design Procedure),

2 procedures for the design of architectural glazingsystems for impacts from windborne debris in hur-ricane (typhoon) and non-hurricane applications(Section 1, Designs for Windborne Debris), and

3 a basis for the use of LAG in wind, snow, andimpact resistant designs that recognizes the fundamental strengths and attributes of this glazing product.

Further, the Guide embraces the latest technology fromASTM E1300-97, recently completed research, andnational standards and building codes to provide thedesigner with guidance, tools and technology to opti-mize designs of architectural glazing with regard tostrength, economy and performance.

THE FUTUREThere is a clear trend in the current construction environment toward preservation of the building envelope and the prevention of glass particle falloutfrom architectural glazing systems should breakageoccur (Reference 4.13). Further, there is a growing recognition of the value of “passive” components in the building envelope that can perform in the face ofsevere environments (windstorms, earthquakes, man-made hazards) without special preparation. Additionalresearch, technological advancements and productdevelopment such as structural glazing applications continue to highlight LAG as the product of choice for passive building envelope protection.

Closure

Length (in.)

Wid

th (m

m)

Wid

th (i

n.)

Length (mm)500

20 30 40 50 60 70 80 90 100 110

1,000 1,500 2,000 2,500

1,000

1,500

500

0

55

50

45

40

35

30

25

20

15

10

5

0

AR = 2

AR = 3

AR = 4

AR = 5

0.5 (10)

0.75 (16)

1.0 (21)

1.25 (28)1.5 (31)

2.5 (52)2.0 (42)

AR =

1

kPa (psf)

39

20

1,500

500

1,000

500

0

30 40 50 60 70 80 90 100 110 120

70

60

50

40

30

20

10

01,000 1,500 2,000 2,500 3,000

kPa (psf)

2.5 (52)2.0 (42)

0.75 (16)

1.5 (31)1.25 (26)

1.0 (21)

0.5 (10) AR =

1

AR = 2

AR = 3

AR = 4

AR = 5

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

20

1,500

500

1,000

500

0

30 40 50 60 70 80 90 100 110

60

50

40

30

20

10

01,000 1,500 2,000 2,500 3,000

kPa (psf)

2.5 (52)2.0 (42)

0.75 (16)

1.5 (31)1.25 (26)

1.0 (21)

AR =

1

AR = 2

AR = 3

AR = 4

AR = 5

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

0

30 40 50 60 70 80 90 100 110 120

80

70

60

50

40

30

20

10

01,000 1,500 2,000 2,500 3,000 3,500

130 140

2,000kPa (psf)

2.5 (52)2.0 (42)

0.75 (16)

1.5 (31)

1.25 (26)

1.0 (21)

AR =

1

AR = 2

AR = 3

AR = 4

AR = 5

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

0

30 40 50 60 70 80 90 100 110 12090

80

70

60

50

40

30

20

10

01,000 1,500 2,000 2,500 3,000

2,000

130 140

3,500

kPa (psf)

2.5 (52)2.0 (42)

0.75 (16)

1.5 (31)1.25 (26)

1.0 (31)

AR =

1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

25

1,500

500

1,000

500

0

50 75 100 125 150 175 200

100

75

50

25

01,000 1,500 2,000 2,500 3,000

2,000

2,500

3,500 4,000 4,500 5,000

kPa (psf)

2.5 (52)2.0 (42)

0.75 (16)

1.5 (31)

1.25 (26)

1.0 (21)

AR =

1

AR = 2

AR = 3

AR = 4

AR = 53.0 (63)

4.0 (84)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

CHARTS A.1-A.12 GLASS THICKNESS SELECTION CHARTS

Appendix

CHART A.1 2.5 mm (3/32 in.) Glass

CHART A.2 2.7 mm Glass CHART A.5 5.0 mm (3/16 in.) Glass

CHART A.3 3.0 mm (1/8 in.) Glass CHART A.6 6.0 mm (1/4 in.) Glass


40

Appendix

1,500

1,000

500

0

50 75 100 125 150 175 200

100

75

50

25

01,000 1,500 2,000 2,500 3,000

2,000

2,500

3,500 4,000 4,500 5,000

3,000

4.0 (84)

kPa (psf)

2.5 (52)2.0 (42)

1.5 (31)

1.25 (26)

1.0 (21) AR =

1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

0

50 75 100 125 150 175

125

100

75

50

25

01,000 1,500 2,000 2,500 3,000

2,000

2,500

3,500 4,000 4,500

3,000

4.0 (84)

kPa (psf)

2.5 (52)2.0 (42)

1.5 (31)

1.25 (26)

1.0 (21) AR = 1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

50 75 100 125 150 175

150

125

100

75

50

251,000 2,000 3,000

2,000

2,500

4,000 5,000

3,000

3,500

4,000

200

kPa (psf)

2.5 (52)2.0 (42)

1.5 (31)

1.25 (26)

1.0 (21) AR = 1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)4.0 (84)

5.0 (104)7.0 (146)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

50 75 100 125 150 175

150

125

100

75

50

251,000 2,000 3,000

2,000

2,500

4,000 5,000

3,000

3,500

4,000 200

1,500 2,500 3,500 4,500

kPa (psf)

2.5 (52)

2.0 (42)

1.5 (31) AR = 1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

4.0 (84)5.0 (104)

7.0 (146)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

50 75 100 125 150 175

150

125

100

75

50

251,000 2,000 3,000

2,000

2,500

4,000 5,000

3,000

3,500

4,000 200

1,500 2,500 3,500 4,500

kPa (psf)

2.5 (52)

2.0 (42)AR

= 1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

4.0 (84)5.0 (104)

7.0 (146)10.0 (209)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)

1,500

1,000

500

75 100 125 150 175

150

125

100

75

50

252,000 3,000

2,000

2,500

4,000 5,000

3,000

3,500

4,000 200

1,500 2,500 3,500 4,500

kPa (psf) 2.5 (52)AR = 1

AR = 2

AR = 3

AR = 4

AR = 5

3.0 (63)

4.0 (84)

5.0 (104)

7.0 (146)

10.0 (209)

Length (mm)

Wid

th (m

m)

Wid

th (i

n.)

Length (in.)





41

2

1.5

15 20 25 0.50

400 600

3

4

800

5

6

12

305 500 700 900 1,000 1,200 1,390

0.40

0.30

0.20

0.15

0.10

0.07

0.05

8

10

12 30 35 40 45 50 55

10 psf (0.5 kPa)20 psf (1 kPa)

40 psf (2 kPa)


40 psf (2 kPa)

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

Aspect Ratio 1

Aspect Ratio 2

CHART A.13a 3.0 mm (1/8 in.) Glass

27

0.60

690

4

800

6

12

1,000 1,200

0.30

0.20

8

10

30 35 40 45 50 55

1416

0.40

0.50

60 65 70 75 80

1,400 1,600 1,800 2,200

1820 0.802325

85 90 95 100

0.15

1.00

0.25

0.35

900 2,665


80 psf (4 kPa)


80 psf (4 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)Ce

nter

Def

lect

ion

(mm

)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13d 8.0 mm (5/16 in.) Glass

2.5

20 250.60

600

3

4

800

6

12

510 1,000 1,200

0.30

0.25

0.20

0.15

0.10

8

10

30 35 40 45 50 55

1416

0.40

0.50

0.35

60 65 70 75 80

1,400 1,600 1,800 2,030


40 psf (2 kPa)


40 psf (2 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13b 5.0 mm (3/16 in.) Glass

0.60

4815

6

12

1,000 1,200

0.30

0.20

8

10

32 35 40 45 50 55

14

16

0.40

0.50

60 65 70 80

1,400 1,600 1,800 2,200

18

23

0.700.8020

2590 100

0.15

1.00

0.25

0.35

900 2,600

5

2,920

110

0.90

Aspect Ratio 1

Aspect Ratio 2


80 psf (4 kPa)


80 psf (4 kPa)

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13e 10.0 mm (3/8 in.) Glass

20 25

0.6

600

3

4

800

6

12

510 1,000 1,200

0.3

0.2

0

8

10

30 35 40 45 50 55

1416

0.4

0.5

60 65 70 75 80

1,400 1,600 1,800 2,030

1820

0.70.8


80 psf (4 kPa)


80 psf (4 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13c 6.0 mm (1/4 in.) Glass

0.6

6

12

1,000 1,200

0.3

0.2

8

10

42 45 50 55

14

16

0.4

0.5

60 65 70 80

1,400 1,600 1,800 2,000

18

22

0.7

20

2590 100

1.0

3,000

5.5

3,420

120

0.8

2,500

7

9

135


80 psf (4 kPa)


80 psf (4 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13f 12.0 mm (1/2 in.) Glass

CHARTS A.13a-A.13i DEFLECTIONS IN GLASS PLATES

42

0.6

12

1,200

0.3

0.25

8

10

45 50 55

14

16

0.4

0.5

60 65 70 80

1,400 1,600 1,800 2,000

18

23

0.720

2590 100

1.0

2,800 3,300

110

0.8

2,200

7

9

130

2,400

11

13

15

17

19

21

85 12075


140 psf (7 kPa)


140 psf (7 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13g 16.0 mm (5/8 in.) Glass

0.60

12

14

16

0.40

0.50

65 70 80

1,700 1,800 2,000

18

23

0.70

20

2590 100

1.00

2,800 3,600

110

0.80

2,200

130

2,400

11

13

17

19

21

85 12075

15

22

24

95 140

0.90

0.65

0.45

0.55

0.75

0.85

095

2,600 3,000 3,300


160 psf (8 kPa)


160 psf (8 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13i 22.0 mm (7/8 in.) Glass

0.60

12

0.35

10

14

16

0.40

0.45

60 65 70 80

1,475 1,600 1,800 2,000

18

22

0.70

20

2590 100

1.00

3,000 3,300

120

0.80

2,2009

140

2,400 2,600 2,800 3,600

75 110 130

0.50

0.9024


140 psf (7 kPa)


140 psf (7 kPa)

Aspect Ratio 1

Aspect Ratio 2

Width (mm)

Cent

er D

efle

ctio

n (m

m)

Cent

er D

efle

ctio

n (in

.)

Width (in.)

CHART A.13h 19.0 mm (3/4 in.) Glass

Appendix

43

Note: Percentages are for spacer dimension to loaded plate thickness ratio (S/tL) of 2.0 or larger (source: Reference 1.2).

TABLE A.14 Load Sharing in Asymmetrical IG Units% of Applied Load Carried by Loaded Lite

Thickness of unloaded lite ÷ thickness of loaded lite (tU/tL)

0.5 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

60 93 92 88 86 84 84 68 68 68

80 92 88 81 76 71 71 54 54 54

100 90 85 73 63 58 58 35 35 35

120 88 82 68 58 48 43 28 25 22

140 86 81 67 54 44 37 25 21 18

160 85 80 66 52 42 32 23 20 15

>160 80 75 63 50 38 28 23 18 14

TABLE A.15 Thickness Designations for Laminated Glass

Designation, mm Traditional Designation Nominal Decimal, in.1.0 Micro-Slide 0.04

1.5 Photo 0.06

2.0 Picture 0.08

2.5 Single 0.09

2.7 Lami 0.11

3.0 Double – 1/8" 0.12

5.0 3/16" 0.19

5.5 7/32" 0.21

6.0 1/4" 0.23

8.0 5/16" 0.32

10.0 3/8" 0.39

12.0 1/2" 0.49

16.0 5/8" 0.63

19.0 3/4" 0.75

22.0 7/8" 0.87

25.0 1.0" 1.00

TABLE A.16 Equivalent Monolithic Glass Thickness for Laminated Glass Under Long-Term Load at Room Temperature (75˚F, 24˚C)

Laminated Glass Equivalent MonolithicThickness Glass Thickness

3/16 in. (5 mm) 5/32 in. (4 mm)

1/4 in. (6 mm)* 3/16 in. (5 mm)

5/16 in. (8 mm)** 1/4 in. (6 mm)

3/8 in. (10 mm)*** 5/16 in. (8 mm)7/16 in. (11 mm)***

1/2 in. (12 mm) 3/8 in. (10 mm)9/16 in. (13 mm)

5/8 in. (16 mm) 1/2 in. (12 mm)

3/4 in. (19 mm) 1/2 in. (12 mm)

* If least dimension (W) > 80 in. (2030 mm), use 1/4 in. (6 mm)** If least dimension (W) > 90 in. (2290 mm), use 5/16 in. (8 mm)

*** If least dimension (W) > 100 in. (2540 mm), use 3/8 in. (10 mm)

Least dimension of lite÷

thickness of loaded lite(W/tL)

44

ABBREVIATIONSAAMA American Architectural Manufacturers Association

AN Annealed glass

ANSI American National Standards Institute

ASCE American Society of Civil Engineers

ASTM American Society for Testing and Materials

AR Aspect ratio (in ASTM E1300-97)

BOCA Building Officials and Code Administrators,International, Inc.

CGI Construction Glazing Inc.

CPSC Consumer Product Safety Commission

CT Chemically Tempered Glass

DOE Department of Energy

FT Fully tempered glass

GT Glass type factor

HS Heat strengthened

IG Insulating glass

LAG Laminated architectural glass

PVB Polyvinyl butyral

PET Polyethylene terephthalate

SBCCI Southern Building Code Congress, International

SFBC South Florida Building Code

TDI Texas Department of Insurance

SYMBOLSb short dimension of glass lite (in ASTM E1300-97)

E experiment

ft feet

ft/sec, fps feet per second

GCpi pressure coefficient (in ASCE 7-98)

gm gram

H long dimension of glass lite (H=L)

H/W Height/width

Kip 1000 pounds

kPa kilopascals

ksi Kips per square inch

L long dimension of glass lite

LtL load on loaded lite (IG)

LuL load on unloaded lite (IG)

lbs/ft2 pounds per square foot (also psf)

mm millimeters

mph miles per hour

N North

P wind or snow load in psf or kPa

psf pounds per square foot (also lbs/ft2)

psi pounds per square inch

SE Southeast

sec second

sq ft, ft2 square feet

T theory

t glass thickness

tL thickness of loaded lite (IG)

tU thickness of lite opposite loaded lite (IG)

U unsupported span

W short dimension of glass lite

wk week

in., " inches

�1, �2 principal stresses

% percent

˚F degrees Fahrenheit

Appendix

45

GLOSSARYannealed glass (AN) glass which has been cooled slowly

to eliminate residual stresses

aspect ratio the ratio between the largest opening dimension and the smallest opening dimension

asymmetrical IG unit an insulating glass (IG) unit which haslites of unequal thickness and/or different heat treatment

atrium an open space within a building, usually having a glass roof

bending behavior glass lites which act principally in bending when under load

building codes documents which prescribe acceptable building practices

compression ply the ply which is placed in compression by applied load (same side of lite with larger load)

dead load the weight of the glazing product itself

deflection the displacement in a glass lite which is under load

design pressure(s) the pressure associated with dead, wind and/or snow loads used in the design of glass products

destructive tests tests to failure to obtain glass lite strengths

facade the curtain wall or other building envelope

fully tempered glass (FT) heat treated glass which has a highlevel of temper (ASTM C1048-85)

glazing glass or glasslike material installed on a building as a facade, skylight, etc.

heat strengthened glass (HS) heat treated glass which contains an intermediate level of temper (ASTM C1048-85)

heat treatment the tempering process in which heat is used to increase the strength of annealed (AN) glass

human impact load the force used in the safety glazing standards (CPSC16 CFR1201 and ANSI Z97.1-1984) to represent a human hitting a glass lite

human loads the weight of a human acting on a glass product

impact loads the force of humans, windborne debris, hail and other objects which may strike glass products

insulating glass (IG) two glass lites separated and joined by a perimeter spacer which seals the enclosed airspace

interlayer the plastic (polyvinyl butyral) material used to bond the lites of laminated glass (e.g., Saflex®

interlayer by Solutia)

interlayer thickness the thickness of the plastic interlayer

laminated glass two plies of glass bonded together with a PVB interlayer (e.g., Saflex® interlayer)

“layered” glass two plies of glass in contact with each other in which there is no interlayer or in which the interlayer is considered not to be contributing to the load carrying capacity of the lite

lite a single piece of glass, monolithic or laminated

load duration factor a factor which accounts for the time dependent strength of glass

load sharing the proportioning of design pressures between lites in an insulating glass (IG) unit

membrane behavior glass lites which act principally as membranes when under load

missile impact windborne debris or other objects striking glass

monolithic glass a solid plate of glass

ply (plies) layer(s) of glass in a laminated glass unit

non-destructive tests tests of glass lites to obtain experimental data (stresses, displacements) without breaking

non-linear a non-proportional relationship between pressure and deflection or stress

pressure the uniformly distributed load (dead, wind, snow) which is used in the design of glass products

residual surface compression compressive stresses induced on the surface of a glass plate by heat treatment processes

skylight a transparent opening in a roof, usually laminated glass

snow load pressures used in the design of glass products (usually sloped glazing) to resist the effects of snow

spandrel glass lites on the face of a building between floors, i.e. between vision lines

static fatigue the phenomenon which defines the time dependent strength of glass

stress the intensity of forces within a glass lite which is under load

symmetrical IG unit an insulating glass (IG) unit which has lites of equal thickness and identical heat treatment

tension ply the ply which is placed in tension by applied load (opposite side of lite with larger load)

windborne debris objects carried by the wind during a windstorm, especially hurricanes

wind load pressures used in the design of glass products to resist the effects of wind

46

REFERENCES

1.1 Standard Practice for Determining the Load Resistanceof Glass in Buildings, ASTM E-1300-97, AmericanSociety for Testing and Materials, WestConshohocken, PA, 1997.

1.2 Chou, G.D., Minor, J.E., Vallabhan, C.V.G., “TheStructural-Mechanical Behavior of Insulating GlassUnits,” Glass Research and Testing Laboratory,Texas Tech University (NTIS Acc. No. PB86124614/AS), Lubbock, TX, July 1986.

1.3 South Florida Building Code, Metropolitan DadeCounty, Miami, Florida, adopted December 14,1993; Broward County, Ft. Lauderdale, Florida,adopted February 10, 1994.

1.4 SBCCI Test Standard for Determining ImpactResistance from Windborne Debris, SSTD 12-97,Southern Building Code Congress, International,Birmingham, AL, 1997.

1.5 Standard TDI 1-98: Test for Impact and Cyclic WindPressure Resistance of Impact Protective Systems andExterior Opening Systems, Appendix E to BuildingCode for Windstorm Resistant Construction, 27 TAC§5.4008, Texas Department of Insurance, Austin,TX, effective September 1, 1998.

1.6 Standard Test Method for Performance of ExteriorWindows, Curtain Walls, Doors and Storm ShuttersImpacted by Missile(s) and Exposed to Cyclic PressureDifferentials, ASTM E1886-97, Annual Book ofASTM Standards, Vol. 04.11, ASTM Inc., WestConshohocken, PA, 1997.

1.7 Minimum Design Loads for Buildings and OtherStructures, ASCE 7-98, American Society of CivilEngineers, New York, 1995.

1.8 The BOCA National Building Code, Building Officialsand Code Administrators, International, Inc.,Country Club, IL, 1996.

1.9 Pantelides, C.P., Horst, A.D. and Minor, J.E., “PostBreakage Behavior of Heat-StrengthenedLaminated Glass under Wind Effects,” Journal of Structural Engineering, ASCE, Vol. 119, No. 2,February 1993, pp. 454-467.

1.10 Behr, R.A. and Belarbi, A., “Seismic Test Methodsfor Architectural Glazing Systems,” EarthquakeSpectra, Vol. 12, No. 1, February 1996, pp 129-143.

1.11 Behr, R.A., Belarbi, A., and Brown, A.T., “SeismicPerformance of Architectural Glass in a StorefrontWall System,” Earthquake Spectra, Vol. 13, No. 3,August 1995, pp 367-391.

1.12 Safety Performance Specifications and Methods of Testfor Safety Glazing Material Used in Buildings, ANSIZ97.1-1984, American National StandardsInstitute, New York, NY, 1984.

1.13 Safety Standard for Architectural Glazing Materials,Federal Standard CPSC 16 CFR 1201, 1980.

2.1 Specification for Heat Treated Flat Glass-Kind HS,Kind FT Coated and Uncoated Glass, ASTM C1048-92, ASTM, Inc., West Conshohocken, PA, 1992.

2.2 Behr, R.A. and Kremer, P.A., “Performance ofLaminated Glass Units under Simulated WindborneDebris Impacts,” Journal of Architectural Engineering,ASCE, Vol.2, No. 3, September 1996, ASCE, Reston,VA pp. 95-99.

3.1 Behr, R.A., Minor, J.E., and Norville, H.S., “TheStructural Behavior of Architectural LaminatedGlass,” Journal of Structural Engineering, ASCE, Vol. 119, No. 1, January 1993, pp 202-222.

3.2 Behr, R.A., Minor, J.E., Linden, M.P. andVallabhan, C.V.G., “Laminated Glass Units UnderUniform Lateral Pressure,” Journal of StructuralEngineering, ASCE, Vol. 111, No. 5, Proc. Paper19726, May 1985, pp. 1037-1050.

3.3 Behr, R.A., Minor, J.E. and Linden, M.P., “LoadDuration and Interlayer Thickness Effects onLaminated Glass,” Journal of Structural Engineering,ASCE, Vol. 112, No. 6, Proc. Paper 20703, June1986, pp.1441-1453.

3.4 Minor, J.E. and Reznik, P.L., “Failure Strengths ofLaminated Glass,” Journal of Structural Engineering,ASCE, Vol. 116, No. 4, Proceeding Paper 24564,April 1990, pp. 1030-1039.

Appendix

47

3.5 King, K.W. and Norville, H.S., “The Effect ofInterlayer Thickness on Laminated GlassStrength,” Glass Research and Testing Laboratory,Texas Tech University, Lubbock, TX, February 21,1997, 165 pp.

3.6 Minor, J.E., “Cladding Designs Must ConsiderLocal Windstorm Environment,” Proceedings, 67thRegional Conference (Chicago IL, April 15-18, 1996),Council on Tall Buildings and Urban Habitat,Lehigh University, Lehigh, PA, 1996, pp 341-347.

4.1 Minor, J.E., “Windborne Debris and the BuildingEnvelope,” Journal of Wind Engineering andIndustrial Aerodynamics, Vol. 53 (1994), pp 207-227.

4.2 Minor, J. E. and Behr, R. A., “Architectural GlazingSystems in Hurricanes: Performance, DesignCriteria and Designs,” Proceedings, the 7th NationalConference on Wind Engineering, (University ofCalifornia, Los Angeles, June 27-30, 1993), UCLA,Los Angeles, 1993, pp. 453-461.

4.3 Behr, R. A. and Minor, J. E., “A Survey of GlazingSystem Behavior in Multi-Story Buildings DuringHurricane Andrew,” The Structural Design of TallBuildings, Vol. 3, 1994, pp. 143-161.

4.4 Minor, J.E., “Window Glass Performance andHurricane Effects,” Proceedings, ASCE SpecialtyConference on Hurricane Alicia: One Year Later(Galveston, TX, August 16-17, 1984), ASCE, NewYork, 1985, pp. 151-167.

4.5 Minor, J. E. and Mehta, K. C., “Wind DamageObservations and Implications,” J. Structural Div.,ASCE, Vol. 105 (1979), pp 2279-2291.

4.6 Minor, J.E., “Window Glass in Windstorms,” CivilEngineering Report Series CE74-01, Texas TechUniversity, Lubbock, TX, May 1974, 168 pp.

4.7 Minor, J. E., McDonald, J. R., and Mehta, K. C.,“The Tornado: An Engineering OrientedPerspective,” NOAA Technical Memorandum ERLNSSL-82, National Weather Service, NOAA,Washington, DC, 1978 (reprinted as NOAATechnical Memorandum NWS SR-147, 1993).

4.8 “Interim Guidelines for Building OccupantProtection from Tornadoes and Extreme Winds,”Defense Civil Preparedness Agency, Washington,DC, 1975.

4.9 Minor, J. E., Beason, W. L., and Harris, P.L.,“Designing for Windborne Missiles in Urban Areas,”Journal of the Structural Division, ASCE, Vol. 104,No. ST11, November 1978, pp. 1749-1759.

4.10 “Natural Phenomena Hazards Design andEvaluation Criteria for Department of EnergyFacilities,” DOE-STD-1020-94, U.S. Department ofEnergy, Washington, DC, April, 1994.

4.11 Sparks, P.R., Schiff, S.D., and Reinhold, T.A., “WindDamage to Envelopes of Houses and ConsequentInsurance Losses,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 53 (1994), pp 145-155.

4.12 Pantelides, C. P., Horst, A. D., and Minor, J. E.,“Post-breakage Behavior of Architectural Glazingin Windstorms,” J. Wind Engin. and Indus. Aerody.,Vol. 41-44 (1992), pp 2425-2435.

4.13 Minor, J.E., “New Philosophy Guides Design of theBuilding Envelope,”Proceedings, ASCE StructuresCongress (April 14-16, 1997, Portland, OR), ASCE,Reston, VA, pp 1-5.

48

SPECIFICATIONHow to specify Laminated Architectural Glass withSaflex® interlayer

Following is an example of the recommended procedurefor the specification of laminated architectural glasswith Saflex® interlayer.

Laminated architectural glass consisting of (number)lites of (type, thickness, treatment) glass with (clear orcolor designation) Saflex interlayer by Solutia.

The glass shall meet minimum requirements as specifiedin ASTM C1036-85.

For solar control add:The laminate shall have a visible light transmittance of (value) % with a shading coefficient of (value) and a maximum UV energy transmittance of < 1% below380 nm.

For safety applications add:The laminate shall comply with CPS 16 CFR 1201,Category (I or II), Safety Glazing Test Standard and/orANSI Z-97.1

For security applications add as appropriate:The laminate shall meet UL 972 (for burglary resistance)or UL 752 (for bullet resistance).

For sound control add:The laminate or the glazing unit shall have an STC, OITC or Rw rating of (value).

For an insulating glass unit:The laminate shall be installed as (interior, exterior,both) lites. (For sloped glazing, laminate should always be an interior lite.)

Appendix

St. LouisP. O. Box 66760St. Louis, MO 63166-6760tel 314-674-1000fax 314-674-3439

BelgiumSolutia Europe N.V./S.A.Rue Laid Burniat, 3Parc Scientific-FlemingB-1348 Louvain-la-Neuve (Sud)Belgiumtel 32.10.48.12.11fax 32.10.48.12.12

South AmericaSolutia Brazil Ltda.Rua Gomes de Carvalho1306-60 Andar 04547-005Sao Paulo, SP, Braziltel 55-11-5087-3000fax 55-11-5087-3030

SingaporeSolutia Singapore Pte. Ltd.101 Thomson Road#19-00 United SquareSingapore 307591tel 65-355-7239fax 65-254-3138

Notice:Although the information and recommendations set forth herein (hereafter “Information”) are presented in good faith and believed to be correctas of the date hereof, Solutia Inc. makes no representations or warranties as to the completeness or accuracy thereof. Information is supplied upon the con-dition that the persons receiving same will make their own determination as to its suitability for their purposes prior to use. In no event will Solutia Inc. beresponsible for damages of any nature whatsoever resulting from the use of or reliance upon Information or the product to which Information refers. Nothingcontained herein is to be construed as a recommendation to use any product, process, equipment or formulation in conflict with any patent, and SolutiaInc. makes no representation or warranty, express or implied, that the use thereof will not infringe any patent. NO REPRESENTATIONS OR WARRANTIES,EITHER EXPRESS OR IMPLIED, OR MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR OF ANY OTHER NATURE ARE MADE HEREUNDER WITHRESPECT TO INFORMATION OR THE PRODUCT TO WHICH INFORMATION REFERS.

© 2007 Solutia Inc. SAFLEX® and SOLUTIA AND INFINITY LOGO® are trademarks of Solutia Inc., registered in the U.S. and other countries. Printed in the U.S.A.

For more information on laminated glass with Saflex interlayer, visit our Website on the Internet at www.saflex.com

or call (800) 24-TOUGH [800-248-6844].

Saflex Regional Sales Offices

Documents

Saflex Structural Guide