Post-fire behaviour and residual resistance of hot-rolled stainless steel channel sections under major-axis combined loading

Abstract

This paper presents experimental and numerical investigations into the post-fire local buckling behaviour and residual resistance of hot-rolled stainless steel channel sections under combined compression and major-axis bending. The experimental investigation included heating and cooling of specimens as well as post-fire material testing, initial local geometric imperfection measurements and fourteen eccentric compression tests. A subsequent numerical investigation was performed, where finite element models were developed to simulate the test results and then used to conduct parametric studies to generate additional numerical data over a wide range of cross-section dimensions and loading combinations. Due to the lack of specific design standards for stainless steel structures after exposure to elevated temperatures, the relevant ambient temperature design interaction curves, as set out in the European code and American specification, were evaluated, using post-fire material properties, for their applicability to hot-rolled stainless steel channel sections under major-axis combined loading after exposure to elevated temperatures. The evaluation results revealed that the codified design interaction curves result in conservative post-fire residual resistance predictions, due to the conservative end points and inefficient shapes. Finally, new design interaction curves, with more accurate end points and efficient shapes, were proposed and shown to provide improved design accuracy than the codified design interaction curves for hot-rolled stainless steel channel sections under major-axis combined loading after exposure to elevated temperatures.