Abstract

The present study examines the suitability of the current wind provisions of the National Building Code of Canada for design wind loads on gable roofs of intermediate roof angles (10$\sp\circ$-30$\sp\circ$). The study is initiated by the discrepancies found in recent research projects against the current design wind loading provisions for such roofs. Five building models with roof angles of 10$\sp\circ$, 15$\sp\circ$, 20$\sp\circ$, 25$\sp\circ$ and 30$\sp\circ$ equipped with an interchangeable roof slope panel have been tested in a typical open country exposure in the boundary layer wind tunnel of the Centre for Building Studies at Concordia University. The experimental settings satisfy the corresponding wind tunnel simulation criteria specified in the wind load test standards of American Society of Civil Engineers. Local and area-averaged roof pressure coefficients have been obtained from the wind tunnel measurements. Extreme value analysis has been performed to establish the peak pressure coefficient values. This thesis presents a comparative study based on the experimental data, which consists of two parts. The first part includes the comparisons of the measured results with those from other researches. The comparisons show that the present experimental results are appropriate and suitable for application to codification. The second part of the study examines the suitability of the current wind provisions by comparing the present results with those specified in the provisions. It appears that there is underestimation of the extreme suctions in the current wind provisions, particularly those on the ridge and edge regions of the roofs with intermediate slopes. As a result of the present study, an alternative zoning and loading definition is attempted, accompanied by a set of new curves. At the same time, the codal roof categories are rearranged. The proposed design roof wind pressure coefficients are somewhat higher than the current design values