A consistent nonlinear approach for analysing steel, cold-formed steel, stainless steel and composite columns at ambient and fire conditions

This paper presents a consistent nonlinear 3-D finite element approach, adopted by the author over the last ten years, for analysing steel, cold-formed steel, stainless steel and composite columns at ambient and fire conditions. The main parameters affecting the finite element approach, which has accounted for the nonlinear material properties of the column cross-sections at ambient and elevated temperatures, initial local and overall geometric imperfections and residual stresses, are highlighted in this paper. The finite element approach could be easily extended to study columns constructed from other materials or built-up using different sections. This paper also presents up-to-date review for previously published experimental and numerical investigations highlighting the stability of the aforementioned columns at ambient and elevated temperatures. In addition, the paper highlights the design rules specified in current codes of practice for the columns. Furthermore, this paper presents, as examples, comparisons of finite element analysis results, previously reported by the author, with design values calculated using of current codes of practice. In overall, the paper aims to stress the fact that consistent, robust and efficient nonlinear 3-D finite element models could improve and assess the accuracy of design rules specified in current codes of practice at ambient and elevated temperatures. Also, better understanding of the structural performance of the columns in the cold condition is essential to analyse the column behaviour under severe fire conditions.

► A consistent nonlinear approach for different columns was presented.
► The main parameters affecting the finite element approach was detailed.
► Up-to-date review of existing investigations on the field was presented.
► Current design codes of practice were highlighted.
► Comparisons of numerical results and design predictions were highlighted.