Pseudo-plastic Collapse Performance of Multi-span Continuous Beams with CFS Sigma Sections: A Numerical Study

Conventional design approaches for cold-formed steel (CFS) members were mainly based on elastic theory, including the effective width method and the direct strength method, where the influence of moment redistribution on the failure load was neglected. A Pseudo-Plastic Design Method (PPDM) has been presented for analysing multi-span CFS structures in order to enhance the economical of resistance prediction. This method is analogical to conventional plastic design theory as it introduces a pseudo-plastic moment resistance to accommodate the benefit of the redistribution of moments. In the present study, finite element modelling approach was introduced based on ANSYS package, and comparisons were made between numerical and PPDM results, in particular, on load-carrying capacity, pseudo-plastic hinges formation, moment redistribution and failure behaviour. Extensive sensitivity studies have been carried out in validation of PPDM application for full-scale continuous beams under various span number, span length, steel yield strength and cross section properties. The study shows that the design employing PPDM can lead to a better economic benefit than the aforementioned methods for CFS sigma continuous beams.