Fire Endurance Under Design Load for Walls of One-Story Three-Room Structures of Sandwich and Wood-Frame Construction

摘要

Large - scale fire tests were conducted on seven wooden structures to examine the actual endurance times of structural sandwich walls in housing under design loads when exposed to interior fires and to compare endurance times with those for conventional wood - frame structures. Additional study goals were to determine the influence of interior thermal protection and to correlate performances to laboratory results. The seven structures were 16 feet by 24 feet. Four of the structures were of sandwich construction with cores of plastic or paper honeycomb, and three structures were of wood - frame construction. The walls were loaded to a computed design loading. Fire endurance was determined under a fire exposure from a typical building contents loading of 4.5 pounds per square foot of floor area. Two open windows at each end of each structure were wized to obtain a ventilation - controlled fire during the fully developed test. the tests confirmed the poor fire endurance performance of the unprotected sandwich construction as previously indicated by laboratory tests. Interior thermal protection in the form of gypsum wallboard improved the performance of sandwich and wood - frame walls. For fire endurance, conventional wood - frame construction appeared to be better than load - bearing sandwich panels with plywood faces. The tests also showed that 640 degrees was a critical temperature associated with flashover under the fire conditions used. During the early stages of some of the structure tests, the optical density of the fire atmosphere seemed to vary linearly with time. Chemical analysis showed little evidence of hydrogen cyanide accumulation, although this compound could be a degradation product of some of the sandwich panels. The carbon monoxide and carbon dioxide concentrations were consistent with the test structures' geometry, outside weather conditions, and overall stage of fire growth at the time of measurement. A reference list and an appendix presenting photographs, figures, and tables with study results are provided. (Author abstract modified).