Fire design of stainless steel I beams prone to lateral torsional buckling under end moments

It is known that the loading type significantly influences the resistance of steel I-beams to lateral torsional buckling (LTB), which led to the development of Eurocode 3 design rules accounting for the beneficial effect of non-uniform bending in laterally unrestrained beams. New calculation formulae for stainless steel beams under fire conditions have recently been proposed for incorporation in the second generation of Eurocode 3 − their safety evaluation in the context of different bending moment diagrams is still a relevant issue that needs to be investigated. This paper presents a numerical study on the resistance of stainless steel I-beams with slender and non-slender cross-sections and undergoing LTB when acted by end moments at elevated temperatures, focusing on the influence of the moment gradient. The safety and accuracy of the Eurocode 3 design approaches (current and second generation versions), as well as a design proposal previously developed for beams with stocky stainless steel sections, are assessed through the comparison of their predictions with extensive numerical failure moments obtained with the software ANSYS. It is shown that the design proposal previously developed for stainless steel beams with stocky sections provides the best predictions, even if having considerable number of underestimations.