Numerical investigation on local buckling capacity of cold-formed steel compression members made of advanced high strength steels at elevated temperatures

In recent years, the application of advanced high strength steels for fabricating cold-formed steel (CFS) members has been increasingly focused. The knowledge of the load-bearing capacity of CFS members made of these materials at elevated temperatures (in fire conditions) is limited. This research study focuses on the compression capacity of short CFS lipped channel members made of MS1200 martensitic advanced high strength steel sheets (with a nominal yield strength of 1200 MPa) and failing by local buckling at elevated temperatures. Firstly, finite element (FE) models of these CFS members were developed. These FE models were then used to conduct a parametric study, in which the effects of increasing temperatures on the capacity reduction of short CFS lipped channel members made of MS1200 steel sheets were focused. The difference between the capacity reductions due to elevated temperatures of CFS lipped channel members made of G550 high strength steel sheets (with a nominal yield strength of 550 MPa) and MS1200 steel sheets was also discussed. Finally, the direct strength method (DSM) based design rules for CFS compression members at elevated temperatures in the current CFS design standard in Australia and New Zealand (AS/NZS 4600) were assessed using the obtained FE analysis results.