Design Wind Loads on Gable-Ended Low-Rise Buildings with Moderate and Steep Roof Slopes

Abstract

Wind tunnel model studies were carried out to determine the external wind pressure distributions on large, low-rise buildings with roof pitches of 15° and 35°. The studies showed a significant increase in the magnitude of the mean and peak negative pressure coefficients with an increase in length to span aspect ratio, on the downwind roof and leeward wall, near the windward gable-end of buildings with a steep 35° pitch roof, for oblique approach winds. These oblique approach winds also generate large design wind load effects on the frames near the gable-end. There is little variation in mean and peak pressure coefficients with aspect ratio, across the frame of the building with a moderate 15° pitch roof. AS/NZS 1170.2, which specifies increased suction pressures with aspect ratio on the downwind roof slope and leeward wall of steep pitch roofbuildings compared to the previous edition of the Standard, provides satisfactory design wind load effects on frames near the gable-end. However, some design load effects on frames near the gable-end of the 15° pitch roof building are underestimated by AS/NZS 1170.2.