The ultimate strength and stiffness of modern roof systems with hat-shaped purlins

Abstract

In this paper, the strength and stiffness of different roof structures has been investigated, in order to establish their ability to act as in-plane diaphragms for stressed skin design. In each test set-up, a roof panel of approximately 3m x 3m was constructed using top-hat purlins and standard sheeting profiles or composite panels. Different types of roofs, such as single and double skin, have been investigated, all using hat-shaped purlins. A total of 10 roof panels were examined by testing with and without shear connectors placed along the rafters. The experimental strength and stiffness of each panel was then compared against established theoretical methods and the effect of shear connectors was discussed. It was demonstrated that although it is possible to closely estimate the ultimate strength of the structure using standard calculation methods, it is often more difficult to accurately calculate its stiffness. As the panel stiffness is a function of many variables, testing is still the recommended method, in order to investigate the shear flexibility of modern roof panels