Numerical Simulation of Along-Wind Loading on Small Structures Using a Simplified Wind Flow Model. NIST Technical Note 1683

摘要

Aerodynamic measurements of wind-induced pressures on structures are required for the codification of design wind loads. However, the reliable measurement of pressures on low-rise buildings in atmospheric boundary layer (ABL) flow remains a challenge. Two major causes are the difficulty of simulating low-frequency turbulent fluctuations in boundary-layer wind tunnels and the small scale of models that can be accommodated in typical civil engineering aerodynamic testing facilities, especially for relatively small buildings such as residential homes. To address this issue, a simplified laboratory technique was recently proposed for the accurate and repeatable measurement of pressures on such buildings. The technique rests on the hypothesis that aerodynamic effects induced on small buildings by low-frequency fluctuations with high spatial coherence are equivalent to those induced by an increment in the mean wind speed. Preliminary measurements appear to have validated this hypothesis. The purpose of this study is to present an approximate numerical method for estimating the requisite increment in the mean wind speed. The method is based on the quasi-static representation of the pressures induced on the windward face of a rectangular building by wind normal to that face. The study provides a point of departure for the quantitative definition of simplified flows in future experimental studies.