Codification of wind loads on hip roof overhangs of low-rise buildings

Abstract

Recent funding opportunities for Wind Engineering research have generated a significant amount of knowledge that has the potential to both develop new or enhance existing wind standards and building codes of practice. Building codes tend to get more rigorous over time to better mitigate damage on buildings and structures. Roof overhangs which are an integral part of the roofing system in low-rise buildings, is particularly vulnerable to damage in wind events due to its exposure to wind-induced loads on both upper and lower surfaces. Large scale wind tunnel testing was carried out at the Wall of Wind (WOW) Research Experimental Facility to investigate the wind-induced loads on roof overhangs of low-rise residential buildings. The physical testing protocol included six 1:10 scaled models with varying geometrical parameters such as roof slope and roof overhang width. Peak wind pressures on both the upper and lower surfaces were measured to calculate the simultaneous net pressure coefficients along the overhangs. Area-averaged pressure analysis was carried out to investigate the pressure gradients on single or groups of taps on the overhangs, soffits, and walls. The experimentally derived area averaged GCp values were compared to previous and current versions of wind standards to evaluate their adequacy. The findings revealed that the provisions’ design guidelines are less conservative for some roofing and wall zones, which justified the need for a codification study that can provide enhanced design guidelines for overhangs and adjacent walls. A detailed discussion of the codified design guidelines, which are formed based on statistical determination rather than the enveloped procedures as commonly used, is presented in this paper.