【国外标准】 Standard Practice for Calculating the Superimposed Load on Wood-frame Walls for Standard Fire-Resistance Tests

4.1 Test Methods E119 and E1529, and other standard fire resistance test methods specify that throughout exposures to fire and the hose stream, a constant superimposed axial load be applied to a load-bearing test specimen to simulate a maximum load condition. These test methods specify that this superimposed load shall be as nearly as practicable the maximum allowable axial design load allowed by design under nationally recognized structural design criteria. For this practice, the nationally recognized structural design criteria is the National Design Specification (NDS) for Wood Construction4.1.1 Alternatively, the standard fire resistance test methods shall be conducted by applying an axial load that is less than the maximum allowable axial design load as addressed by the NDS and this practice, but these tests shall be identified in the test report as being conducted under restricted load conditions.4.1.2 The superimposed axial load, as well as the superimposed axial load as a percentage of the maximum allowable axial design load for the stud and as a percentage of the maximum allowable design load for the plate, shall be calculated using the Allowable Stress Design (ASD) method in the NDS and this practice shall be included in the test report.NOTE 1: The NDS should be used to ensure calculation of the superimposed load is in compliance with all applicable provisions of that document. Appendix X1 describes how to calculate the superimposed load in accordance with the NDS.4.2 This practice describes procedures for calculating the superimposed axial load to be applied in standard fire resistance tests of wood-frame wall assemblies.4.3 Statements in either the fire resistance test method standard or the nationally recognized structural design standard supersede any procedures described by this practice.1.1 This practice covers procedures for calculating the superimposed axial load required to be applied to load-bearing wood-frame walls throughout standard fire-resistance and fire and hose-stream tests.1.2 The calculations determine the maximum load allowed by design for wood-frame wall assemblies under nationally recognized structural design criteria.1.3 This practice is only applicable to those wood-frame assemblies for which the nationally recognized structural design criteria are contained in the National Design Specification for Wood Construction (NDS).21.4 The system of units to be used is that of the nationally recognized structural design criteria. For the NDS, the units are inch-pound.1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.1.6 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.1.7 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.