The American Institute of Steel Construction

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by Eric Montplaisir, PE
Many UL designs have load restrictions—a matter of great importance and potential liability for engineers of record (EORs), who, in accordance with several building codes and the UL Fire-Resistance Rating Directory, are responsible for identifying and approving the use of such designs on a project. Understanding which designs are restricted, and calculating the load restrictions, can be a complex process.

Background
The International Building Code (IBC) requires the fire-resistance rating of building elements, components, or assemblies be determined by the test procedures set forth in ASTM E 119,

Standard Test Methods for Fire Tests of Building Construction and whatsapp number database Materials or UL 263, Standard for Fire Tests of Building Construction and Materials. Under these standards, the members being tested must be loaded as near as practicable to the maximum allowed under nationally recognized structural design criteria.


(AISC) provides two methods for calculating the load: Limit States Design method (LSD) and Working Stress Design method (WSD). Until 2006, these methods yielded different results under identical conditions; however, AISC changed the calculation process for WSD (i.e. allowable stress design method) in the 2005 American Institute of Steel Construction (AISC) Specification for Structural Steel Buildings. This change resulted in the two methods generally ending in the same design loads. This change was first adopted in the 2006 IBC.