Strength of Screwed Connections in Crest-Fixed Trapezoidal Steel Claddings

Abstract

Profiled steel cladding systems used in Australia and its neighbouring countries are made of thin, high strength steel and are always crest-fixed. Past research has identified that when crest-fixed steel claddings are subjected to wind uplift/suction forces, local pull-through or dimpling failures occur prematurely at their screwed connections because of the large stress concentrations in the sheeting under the screw heads. A review of current literature and design standards demonstrated the need to improve the current design and testing methods of crest-fixed steel cladding systems under wind uplift/suction loading. Therefore detailed investigations were carried out on two-span cladding assemblies of trapezoidal profiles using laboratory experiments and finite element analyses. The finite element model was then used to study the effects of important geometry parameters on the behaviour and strength of trapezoidal steel claddings. The results were used to develop strength formulae for optimisation and design purposes. This paper presents an overview of the experimental and numerical investigations and their important results. It includes improved non-dimensionalised design strength formulae for screwed connections in trapezoidal steel claddings under static wind uplift loading. Appropriate reduction factors must be used with the formulae to allow for the fatigue effects in cladding systems when they are used in cyclonic areas.