Cross-section resistance and design of stainless steel CHS and EHS at elevated temperatures

The structural behaviour and design of stainless steel circular hollow sections (CHS) and elliptical hollow sections (EHS) at elevated temperatures are investigated in this paper. Shell finite element models of stainless steel CHS and EHS are created and validated against experimental results from the literature, which are subsequently used to generate benchmark structural performance data. Parametric studies are performed on a large number of cold-formed and hot-rolled austenitic, duplex and ferritic stainless steel CHS and EHS subjected to (i) pure axial compression, (ii) pure bending, (iii) combined axial compression and bending and (iv) combined bending and shear at elevated temperatures; the studied cases comprise 24,495 stainless steel CHS and EHS in fire and cover a wide range of cross-section slendernesses and elevated temperature levels. Calibrated against the benchmark structural performance data obtained from the numerical parametric studies, new design proposals for predicting the cross-section resistances of stainless steel CHS and EHS in fire are put forward. The accuracy, safety and reliability of the new design proposals are assessed. It is shown that in comparison to the design provisions of the European structural steel fire design standard EN 1993-1-2, the proposed design methods provide more accurate and safe-sided cross-section resistance predictions for stainless steel CHS and EHS at elevated temperatures.