Transversally loaded stainless steel beams under fire: Local/global behaviour, strength and design

This paper presents and discusses the results of a numerical investigation concerning the post-buckling behaviour, strength and design of stainless steel I-section beams prone to local or global (lateral-torsional) buckling under elevated temperatures. Non-linear shell finite element models are employed to assess the structural response and failure loads of I-beams (i) subjected to distinct loading conditions, namely uniform bending, uniform transverse loading, 3 and 4-point bending (the transverse loadings are applied along either the shear centre, top flange-web or bottom flange-web longitudinal axes), (ii) made from three common stainless steel grades (ferritic 1.4003, austenitic 1.4301 and duplex 1.4462), (iii) subjected to eight temperatures (θ = 100 to 800 °C), and (iv) covering wide local and global slenderness ranges. Special attention is paid to the influence of the transverse loading location (load height effect), a topic lacking research in the context of local buckling, by means of (i) Generalised Beam Theory (GBT) buckling and (ii) ABAQUS shell finite element post-buckling analyses. The last part of the paper is devoted to design considerations, based on the numerical failure loads obtained and involving the assessment of the current Eurocode 3 design rules for stainless steel beams failing in local and global modes.