Low-high-low cyclic tests of steel roof batten systems

Thin-walled steel roofing systems of low-rise buildings are exposed to highly fluctuating suction pressures during cyclones and thus they are often subject to premature, low cycle fatigue pull-through failures at steel roof batten (top hat) to rafter connections. Current fatigue design method is based on full-scale air-box tests of the entire roofing system using the Low-High-Low (LHL) cyclic test sequence, which is time-consuming and expensive. Therefore, a detailed experimental research study consisting of static and constant amplitude cyclic tests was undertaken and a simple hybrid fatigue pull-through design method was developed for steel roof battens. It was developed by considering the sequence and strain rate sensitivity effects of steel that significantly influence the pull-through behaviour and capacity of steel roof battens.