Shear behaviour of screw fastened rectangular hollow flange beams with web openings

Abstract

Cold-formed screw-fastened Rectangular Hollow Flange Channel Beam (RHFCB) is considered as an alternative steel section to welded LiteSteel beam. The simple fabrication procedure of attaching two Rectangular Hollow Section (RHS) as flanges to a web plate with intermittently spaced screws allows for a selection of a wide range of dimensional parameters for optimum design. Generally, web openings are made on such Cold-Formed Steel (CFS) sections to allow for building services. These web openings influence the shear behaviour and cause a reduction in their structural performances. On the other hand, hardly any investigations have been done on the shear behaviour of screw-fastened RHFCB with square/ rectangular/ elliptical web openings. Therefore, to investigate the shear behaviour and capacity of screw-fastened RHFCB with non-circular web openings, a series of experimental shear tests and a detailed numerical study was conducted. The laboratory shear test results were used to validate the developed Finite Element (FE) models of CFS RHFCBs with and without web openings. The influence of different parameters was investigated in a detailed parametric study using developed FE models. The analysis of FE results showed that a significant reduction (max 70%) in the shear capacity observed due to the web openings. The results indicated that the existing shear design equations to predict the shear capacity of CFS screw-fastened RHFCBs are either conservative or unsafe. Hence, a new series of shear design equations for the accurate estimation of the shear strength of screw-fastened RHFCB with unreinforced square, rectangle and elliptical web openings are proposed.