Design of cold-formed stainless steel RHS and SHS beam–columns at elevated temperatures

Numerical investigation of cold-formed stainless steel beam–columns at elevated temperatures ranged from 24–960 °C has been performed. The beam–column specimens were subjected to axial compression and minor axis bending. A finite element model was developed and validated against available experimental results at ambient temperature. An extensive parametric study with 308 lean duplex, austenitic and duplex stainless steel beam–column specimens of square and rectangular hollow section was carried out, and the numerical results were compared with the design strengths calculated by the American Specification, Australian/New Zealand Standard, European Code, and direct strength method. The suitability of these design rules for cold-formed stainless steel beam–columns at elevated temperatures were assessed by reliability analysis. It is shown that the existing design specifications are generally capable of predicting the cold-formed stainless steel beam–column strengths at elevated temperatures, and they are all considered to be reliable according to reliability analysis. The direct strength method provides the most accurate prediction when the carbon steel curve was used. The European Code provided the most conservative prediction among the design rules assessed in this study.