In-Situ Measurement of Wind Loads for Roof Edge Metal Configurations

Abstract

The role of a roof on any building is to separate the interior environment of the building from the exterior environment, thereby making it a crucial component of the building design. Metal roof edges are the first line of defense against wind-induced loads on the roof system; however, data on the nature of these loads acting on the roof edge system is scarce. Previous studies with field measurements of wind pressure acting on the roof edge reported that metal flashings experienced negative pressure. These findings suggest that current building codes in North America (i.e. NBCC and ASCE codes) do not accurately identify wind design loads acting on roof edge systems. The Roof Edge Systems and Technologies (REST) project is a consortium of academia, government and roof industries, which was created to develop testing protocols and design guidelines for roof edges. The work presented in this thesis contributes to the collection and analysis of wind loads acting on metal roof edges, which were installed on the Canada Post building in Vancouver, Canada. The thesis presents the findings and analysis of the measured wind-induced pressure acting on all surfaces of three different edge configurations, namely the Anchor Clip Configuration (ACC), Continuous Cleat Configuration (CCC) and Discontinuous Cleat Configuration (DCC). The analysis showed the presence of negative pressure acting on all three faces of the configurations, in which the type of configuration had minimum effect on the magnitude and nature of the wind-induced loads. Furthermore, the top face of the edge configurations was found to experience the highest suction, and the front face of the edge coping was subjected to a net outward suction force due to the combination of the suction experienced by the coping front face and the positive pressure acting on the cleat. Comparison of these results with current NBCC and ASCE building codes highlight a need to update these codes in order to adequately design metal roof edges against wind action.