Negative External Pressure Coefficients for Design of Components and Cladding of Low-Rise Buildings with Steep-Slope Gable Roofs

Abstract

Negative external pressure coefficients for design of components and cladding of steep-slope gable roofs (27° to 45° roof slope) on low-rise buildings subjected to wind loads were determined in this study based on data from wind tunnel tests of small-scale building models. The effect of exposure and building height were removed from the wind tunnel data, and the peak negative external pressure coefficients were determined using a Gumbel-fitting method. The spatial distribution of area-averaged peak negative external pressure coefficients was examined, and the results indicate that the effect of roof slope is not significant and that the largest magnitude peak negative external pressure coefficients do not always occur in the roof corner zone. Roof zones and equations for negative external pressure coefficients from current ASCE standard are generally in close agreement with the values based on wind tunnel test data, but negative external pressures on the roof edge normal to ridge and near ridge are underestimated. Modified roof zones and equations developed in this study are shown to improve the agreement with wind tunnel test data.