Stainless steel I-section beams at elevated temperatures: Lateral-torsional behaviour and

In this paper, a comprehensive investigation into the structural response and design of stainless steel I-section beams susceptible to lateral-torsional buckling (LTB) at elevated temperatures is carried out. Avery large number of stainless steel I-section beams are considered, taking into account various cross-section geometries, beam slendernesses and different stainless steel grades and elevated temperature levels. Extensive structural performance data on the behaviour of stainless steel I-section beams are generated through nonlinear shell finite element modelling. Assessment of the existing LTB design rules for stainless steel I-section beams at elevated temperatures provided in the current version of the European structural steel fire design standard EN 1993-1-2 and its upcoming version prEN 1993-1-2 is presented. New LTB design rules based upon an Ayrton- Perry equation that is able to provide a consistent mechanical appraisal of the LTB behaviour of stainless steel I-section beams in fire are proposed. The accuracy and safety of the proposed new LTB design rules for stainless steel I-section beams are comprehensively verified. It is also shown that the proposed LTB design equations in this paper lead to a considerably higher level of consistency and reliability for the LTB design of stainless steel I-section beams in fire relative to the LTB assessment rules provided in EN 1993-1-2 and prEN 1993-1-2.