Finite element analysis of cold-formed lean duplex stainless steel columns at elevated temperatures

The behaviour of cold-formed lean duplex stainless steel columns at elevated temperatures was investigated. A numerical investigation on columns of square and rectangular hollow sections were performed at elevated temperatures ranged from 24 to 900 degrees C. A validated numerical model with material properties obtained from tensile coupon tests at elevated temperatures were used in the finite element analysis. A total of 180 numerical column strengths were compared with design column strengths predicted by existing design rules, which do not cover the lean duplex stainless steel material at elevated temperatures. Reliability analysis was carried out to assess the suitability of the existing design rules for lean duplex stainless steel columns at elevated temperatures. It is shown that the existing design rules are generally not suitable for predicting the column strengths, except for the American Specification and the modified direct strength method for stainless steel. The modified direct strength method for stainless steel provides accurate and reliable predictions with relatively simple calculation procedure. Therefore, it is recommended that the modified direct strength method for stainless steel be used for design of cold-formed lean duplex stainless steel columns at elevated temperatures.