Wind-Induced Internal Pressures in Building with Dominant Opening on Hemi-Ellipsoidal Roof

Abstract

Wind-induced internal pressure arising from door or window failure during severe wind conditions has been studied extensively. Most previous studies focus on the cases of openings in the wall, but little attention has been paid to the internal pressure responses of a building with a dominant opening on the roof, although this situation appears frequently due to wind-induced damage or functional use. This paper examines the internal pressure characteristics produced by wind action through a dominant opening on a hemi-ellipsoidal roof and investigates its potential influence factors, including opening sizes, locations, internal volume, and ambient interference. An opening in the wall was also studied and compared with the case having the same size opening on the roof. The study shows that internal pressures were basically negative under roof opening cases but might become positive at several wind azimuths when there is an interfering building nearby. Spectra of internal pressures contained two resonance peaks, which corresponded to Helmholtz resonance and vortex shedding, respectively, and varied significantly with wind directions. Due to the coupling effect of vortex shedding, the classical Helmholtz frequency equation, and the current volume adjustment method to maintain frequency similarity between full-scale and model-scale might be unsuitable for roof opening cases. Reducing the internal volume increased the standard deviation of internal pressure, but had an insignificant effect on its mean values. Compared with the roof opening case, wind actions through an opening in the wall would generate worse net suctions on the roof but lead to a smaller Helmholtz resonance frequency. Roof failure resulted in larger maximum internal suctions than wall failure and was thus more dangerous to the windward wall bearing positive external pressures. Internal pressure responses controlled by Helmholtz resonance could be deemed as a quasi-Gaussian processes. The ambient interferences could affect Gaussian characteristics of internal pressures.