LAUSR

Abstract High strength cold-formed steel channel beams widely used in roof and floor systems carrying steel profiled roof sheeting or floor decking are commonly subjected to a combined action of bending and shear in practice. The design guidelines of such purlins or beams have recently been standardised utilising shear-bending interaction curves in current standards/specifications such as the Australian/New Zealand Standard (AS/NZS 4600:2018) and the North American Specification (NAS S100–2016). In order to investigate different combinations of bending and shear, an experimental program comprising thirty tests of pure bending, combined bending and shear and predominantly shear has been performed at the University of Sydney using a dual actuator test rig. All the tests are conducted on commercial plain C-lipped and Supa-Cee channels. The interaction between bending and shear is governed by varying ratios of bending moments at two ends of the test span. All testing results are plotted against the current interaction curve to validate the performance of the current design method on channel members under different combinations of bending and shear. Further, a completely new concept for the interaction between bending and shear on a theoretical basis of statics is introduced and a development of an explicit Direct Strength Method (DSM) design for the prediction of ultimate strengths of members under combined bending and shear is also provided in this study.