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l Seismic Design Provisionsl Seismic Test Methodsl Conclusionl Referencesl About Architectural Testingl Authors

April 2011

Design Provisions and TestMethods for Architectural GlassSubjected to Seismic InducedBuilding Movements

The reference standards of the current building codes require therelative seismic displacement at glass fallout (fallout) of anindividual glass panel be greater than the actual relative seismicdisplacement of the panel. Exceptions to this requirement aregranted for:

l Glass with sufficient glass-to-frame clearances toaccommodate seismic displacement;

l Fully tempered monolithic glass less than 10 feet abovewalking surfaces and;

l Single thickness laminated glass that is fully captured andwet glazed.

Where the exceptions cannot be applied, the glass fallout shall bedetermined in accordance with AAMA 501.6 or throughengineering analysis.

Both test methods are routinely specified by architects. AAMA501.4-09 is a static racking test method concerned with theserviceability of curtain wall and storefront glazing systemsfollowing a seismic event. This method requires companion airinfiltration, water penetration and static load tests which typicallyrequire a chambered mockup. Thus, this testing is normally donein conjunction with a full air/water/structural performance mockup.

AAMA 501.4 includes the following testing sequence:

l Baseline air leakage (ASTM E 283-91, Standard TestMethod for Determining the Rate of Air Leakage ThroughExterior Windows, Curtain Walls, and Doors UnderSpecified Pressure Differences Across the Specimen)

l Static water resistance (ASTM E 331-00, Standard TestMethod for Water Penetration of Exterior Windows,Skylights, Doors, and Curtain Walls by Uniform Static AirPressure Difference)

l Structural performance at design wind pressure (ASTM E330-02, Standard Test Method for Structural Performanceof Exterior Windows, Doors, Skylights and Curtain Walls byUniform Static Air Pressure Difference)

l Static horizontal racking displacement of design-specificvalue or default value of 0.01 x story height is applied withhydraulic actuators (see Photo No. 1)

l Repeat air leakage, static water resistance and structuralperformance

l Static horizontal racking displacement of 1.5x designvalue.

AAMA 501.6-09, is a dynamic racking test method focusing onthe seismic safety of architectural glass components withincurtain wall and storefront wall systems. This test involvesmounting individual, fully glazed wall panel specimens on adynamic racking test apparatus (see Photo No. 2). The upperanchorage points move back and forth in sinusoidal motions atprogressively higher racking amplitudes, as in a musicalcrescendo (see Figure 1). The bottom anchorage points remainfixed, thereby imparting a dynamic, in-plane story drift on the testspecimen.

Dynamic racking frequencies are 0.8 Hz at lower rackingamplitudes (< 75 mm [3 in.]) and 0.4 Hz at higher rackingamplitudes (> 75 mm). The amplitude at which glass fallout isfirst observed for a given specimen is designated as fallout forthat test specimen. The lowest value of racking displacementcausing glass fallout for three replicate specimens tested inaccordance with AAMA 501.6 is the reported value of fallout forthat particular wall system glazing configuration. This value offallout must be greater than the actual relative seismicdisplacement of the panel for the specific project underconsideration.

Other Links

l ATI Locations

Photo No. 1 Horizontal RackingDisplacement using HydraulicActuator.

Photo No. 2 Dynamic TestingApparatus.

Figure 1 Displacement History ofDynamic Racking Test (From AAMA501.6 with permission).

Developed within the National Earthquake Hazards Reduction Program NEHRP, seismic design provisions forarchitectural glass were adopted in ASCE 7 and are now constituents of all major building codes. Theseprovisions make reference to a specialized laboratory test method developed and published by AAMA.Together, the design provisions and laboratory test methods are intended to improve the life-safetyperformance of architectural glass components in earthquake-prone regions.

l AAMA 501.6-09, Recommended Dynamic Test Method for Determining the Seismic Drift CausingGlass Fallout from a Wall System.

l ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.l 2009 International Building Code.

Architectural Testing continues to search for new ways to diversify our business using our broad capabilitiesand talented staff. Should you require any of our services or know of other unique opportunities where you canutilize our expertise, please don't hesitate to contact us.

Travis HooverProgram Manager of StructuralSystems Testing

Joseph ReedPE Director of Engineering

Mr. Travis Hoover has continual engineering experience since joining Architectural Testing in 1997. Heoversees all AAMA 501.6 testing at Architectural Testing. He has Bachelor of Science in MechanicalEngineering Technology from The Pennsylvania State University. thoover@archtest.com

Mr. Joseph Reed has continual engineering experience since 1988 and joined Architectural Testing in 2002.He is a Professional Engineer licensed in seven states. He has Master of Science in Civil Engineering fromLehigh University. jreed@archtest.com

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