Structural Performance of Metal Sheeting versus Tiled Roofs under Extreme Winds

Houses, the most constructed structures all over the world, can be exposed to extreme winds that may damage their roofs. Generally, roofs are the most vulnerable parts of houses against wind pressure rather than the other elements. Most housing roofs in South Africa are constructed with metal sheeting or tiles as covers, while these systems can exhibit different performance upon their exposure to extreme wind events. The present study is aimed to provide an assessment on the structural behaviour of housing roofs comprising metal and tiled systems under strong winds. Fluid dynamics, wind codes and computational fluid dynamics (CFD) have been employed to analyse and quantify wind loads. Combined wind and dead loads at ultimate limit state served as quasistatic forces acting on roof samples during laboratory experiments. Findings show that cover-to-truss connections are being pulled-out as the sheet deflects under uplift wind forces, even to the removal of batten-to-truss nails when there are no clips. Tiles are cracked gradually till they break as the whole system deflects under wind forces. It can be concluded that the performance of metal sheeting roofs depends on the resistance of cover-to-truss connections against wind pressures, whereas that of tiled roofs depends on the individual resistance of each tile, their interlocking forces, their ability to act as a system, and their attachments’ resistance at the edges.