Research on the attenuation of internal pressure in the large-span cylindrical roof building with a dominant gable opening

Abstract

The internal to external pressure ratio in a large-span cylindrical roof building with a dominant gable opening fluctuates dramatically between 0 and 1, significantly impacted by the attenuation of internal pressure. Current theories usually assume this ratio equal to 1 and overlook the attenuation effect. This study investigates four cylindrical roof models with varying opening areas, scale ratios, and wind speeds by wind tunnel tests. It analyzes ratios of mean (C¯pi/C¯pe), fluctuating (σpi/σpe), and peak (Ĉpi/Ĉpe) internal to external pressure to pinpoint factors affecting the internal pressure attenuation. The results highlight that the most pronounced internal pressure attenuation is at the sideward opening. The vortex shedding around the opening is induced by the wind direction, scale ratio, and wind speed. The attenuation effect decreases with lower frequencies of periodic vortex shedding. This effect generally vanishes when the windward or leeward opening ratio (A1.5/V0) exceeds 0.57%. Empirical design formulas are proposed to predict ratios of internal to external pressure considering the attenuation effect. The inertia (CI) and loss coefficients (CL) affected by the internal pressure attenuation are analyzed to estimate the air slug inertia and damping through the opening. A governing equation, incorporating reduction coefficients (C¯eddy, C̃eddy) from empirical design formulas, is applied to precisely compute the attenuated internal pressure in the large-span cylindrical roof building with a dominant gable opening for engineering risk assessment.