Significance and Use
5.1 This test method is a standard procedure for determining structural performance under uniform static air pressure difference. This typically is intended to represent the effects of a wind load on exterior building surface elements. The actual loading on building surfaces is quite complex, varying with wind direction, time, height above ground, building shape, terrain, surrounding structures, and other factors. The resistance of many windows, curtain walls, and door assemblies to wind loading is also complex and depends on the complete history of load, magnitude, duration, and repetition. These factors are discussed in ASCE/SEI 7 and in the literature (1-8).5
5.2 Design wind velocities are selected for particular geographic locations and probabilities of occurrence based on data from wind velocity maps such as are provided in ASCE/SEI 7. These wind velocities are translated into uniform static air pressure differences and durations acting inward and outward. Complexities of wind pressures, as related to building design, wind intensity versus duration, frequency of occurrence, and other factors must be considered. Superimposed on sustained winds are gusting winds which, for short periods of time from a fraction of a second to a few seconds, are capable of moving at considerably higher velocities than the sustained winds. The analytical procedures in ASCE/SEI 7, wind tunnel studies, computer simulations, and model analyses are helpful in determining the appropriate design wind loads on exterior surface elements of buildings. Generally, wind load durations obtained from ASCE/SEI 7 are 2 s to 10 s and are dependent upon the specific time reference employed in determining the pressure coefficients.
5.3 Some materials have strength or deflection characteristics that are time dependent. Therefore, the duration of the applied test load may have a significant impact on the performance of materials used in the test specimen. The most common examples of materials with time-dependent response characteristics that are used are glass, plastics, and composites that employ plastics. For this reason, the strength of an assembly is tested for the actual time duration to which it would be exposed to a sustained or a gust load, or both, as discussed above. Generally, U.S. practice for wind load testing has been to require a minimum test period of 10 s for test loads equal to the design wind load and proof loads equal to 1.5 times the design wind load. Thus a safety factor is incorporated in the testing. If the design wind load is determined through the analytical procedures of ASCE/SEI 7, the test load shall be based on the nominal loads derived from the load combinations used in allowable stress design. With test loads for wind higher than those determined by ASCE/SEI 7 or of longer time duration than 10 s, the designer must consider what safety factors are appropriate. For test loads that represent design loads other than wind, such as snow load, consideration shall be given to establish an appropriate test period for both design and proof load testing.
5.4 This standard is not intended to account for the effect of windborne debris or cyclic loads. Consideration of cyclic air pressure differentials is addressed in Test Method E1233/E1233M. Consideration of windborne debris in combination with cyclic air pressure differential representing extreme wind events is addressed in Test Method E1886 and Specification E1996.
5.5 This test method is not intended for use in evaluating the structural adequacy of glass for a particular application. When the structural performance of glass is to be evaluated, the procedure described in Test Method E997 or E998 shall be used.
NOTE 1: In applying the results of tests by this test method, note that the performance of a wall or its components, or both, may be a function of fabrication, installation, and adjustment. The specimen may or may not truly represent every aspect of the actual structure. In service, the performance will also depend on the rigidity of supporting construction, temperature, and on the resistance of components to deterioration by various other causes, including vibration, thermal expansion and contraction, etc.
Scope
1.1 This test method describes the determination of the structural performance of exterior windows, doors, skylights, and curtain walls under uniform static air pressure differences, using a test chamber. This test method is applicable to curtain wall assemblies including, but not limited to, metal, glass, masonry, and stone components.2
1.2 This test method is intended only for evaluating the structural performance associated with the specified test specimen and not the structural performance of adjacent construction.
1.3 The proper use of this test method requires a knowledge of the principles of pressure and deflection measurement.
1.4 This test method describes the apparatus and the procedure to be used for applying uniformly distributed test loads to a specimen.
1.4.1 Procedure A (see 11.2) shall be used when a load-deflection curve is not required.
1.4.2 Procedure B (see 11.3) shall be used when a load-deflection curve is required.
1.5 The text of this standard references notes and footnotes which provide explanatory materials. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
