Overall buckling behaviour of superior high-performance steel columns under fire

This paper presents the experimental and numerical investigation on the overall buckling behaviour of superior high-performance (SHP) steel welded I-section columns under fire. Ten full-scale column tests with different slenderness and axial compression ratios being involved were carried out in a vertical test furnace using the transient test method. The test phenomena, failure modes, temperature-time curves, axial displacement-time curves and critical temperatures were obtained and analysed based on the test results. Finite element (FE) models were developed afterward and validated accordingly. Furthermore, comprehensive parametric study was performed to systematically clarify the effects of geometric initial imperfection, residual stress and steel grade on the critical temperature. Comparisons of the FE modelling results with Chinese and European standards indicate that the current design methods need to be modified for the use of the SHP steel. On the basis of the evaluation results, a new set of modified formulae adapting the critical temperature method are proposed in the present work.