Lateral distortional buckling of rivet fastened rectangular hollow flange channel beams

Cold-formed steel hollow flange beams have been commonly used as flexural members in buildings due to their structural efficiency. The rivet fastened Rectangular Hollow Flange Channel Beam (RHFCB) is a new type of cold-formed steel section, characterized by two torsionally rigid hollow flanges connected to a web element. The RHFCB takes advantage of an intermittent fastening method using self-pierce riveting. Buckling analyses have shown that the moment capacity of short-span RHFCB is governed by local buckling while intermediate span RHFCB is governed by the unique lateral distortional buckling. An experimental investigation of RHFCB flexural members was carried out based on a quarter point loading method to investigate their lateral distortional buckling behaviour and moment capacities. It considered the effects of intermittent rivet spacing on the member moment capacity of RHFCBs. The results from the experiments were compared with the member moment capacities predicted using the Australian cold-formed steel structures standard. Following the experimental study, finite element models of tested RHFCBs were developed to simulate the experiments. The developed finite element models were validated by comparison of ultimate moment capacities, applied moment versus deflection curves and failure modes. This paper presents the details of the experimental investigation, the development of finite element models of RHFCBs subject to lateral distortional buckling effects, and the results.