Codification of Wind pressure coefficients for sawtooth roofs

Abstract

Codified pressure coefficients for sawtooth roofs are proposed for use in wind standards and codes of practice. Design pressures are based on boundary layer wind tunnel data obtained using an open country exposure. Local and area-averaged pressure coefficients were measured on models with one, two and four spans and a roof angle of 15 degrees. The proposed design pressure coefficients are expected to be applicale for a range of roof angles from 10 to 30 degrees. In most regions of the roof, critical values of mean and peak suction obtained with the double-span and multi-span models were similar in magnitude to dat obtained with the single-span (mono-sloped roof) model. However, suctions measured near the roof edge in the trough of the double-span and multi-span models were more than 50% larger than corresponding data obtained with the single-span model. A similar trend was also found for positive pressures. Local peak pressure coefficients obtained in the present study are compared with design values specified in the Australian Standard AS 1170.2 (1989). Peak suctions and positive pressures obtained for particular wind directions were generally larger than the values given in AS 1170.2.