Design of Cold-formed Steel Compression Members Subject to Distortional Buckling At Elevated Temperatures

In recent times, light gauge cold-formed steel members have been used extensively in low rise buildings. However, they are susceptible to various buckling modes including local and distortional buckling. Fire safety design of building structures has received greater attention in recent times but mainly for heavier, hot-rolled steel members. The buckling behaviour of light gauge coldformed steel members under fire conditions is not well understood. The buckling effects associated with thin steel construction are significant and have to be taken into account in fire safety design. Therefore, a research project involving both experimental and finite element analyses was undertaken to investigate the distortional buckling behaviour of light gauge cold-formed steel compression members at elevated temperatures. Lipped channel sections made of various thicknesses and both low and high strength steels were designed to buckle distortionally, tested and analysed. The distortional buckling and ultimate strength results from experimental and finite element analyses were then compared with the predictions from the current design methods in order to assess their suitability under fire conditions. This paper presents the details of this investigation and the results.