FULL-SCALE TEST METHODS FOR MULTI-LAYER CLADDING SYSTEMS: WIND TUNNEL VS. MULTI-CHAMBER AIRBOX

摘要

Wind loads on multi-layer wall systems are complicated because the loads on each particular layer are poorly understood and difficult to quantify. This is because of pressure equalization, which is the mechanism whereby the pressures on the external building surface are transmitted through the air-permeable outer layer to interior layers. Recent testing at IBHS in a full-scale wind tunnel has shown that the extent of pressure equalization is more limited than is assumed in the test standard, ASTM D3679-13. Multi-chamber pressure testing performed by the authors at the Insurance Research Lab for Better Homes was able to capture these features in these results using more commonly utilized ASTM-style (airbox) testing. The objective of the current study is to examine the effects that the pressure time history inputs have when comparing the full-scale wind tunnel method data with that from the multi-chamber airbox method. This is accomplished by comparing the power spectral densities of the external and cavity pressures, as well as fitting the peak pressure equalization factor data to a Gumbel distribution. From a comparison of the power spectral densities of each airbox vs. the relevant full-scale, wind-tunnel external pressures, it was noted that larger airboxes created a larger source of error of the peak pressures in the system.