Safety Assessment of Eurocode 3 Stability Design Rules for the Lateral-Torsional Buckling of Prismatic Beams

Abstract

This paper presents the safety assessment of the European rules for the lateral-torsional buckling of beams using hot-rolled I and H cross-sections based on a large number of advanced numerical simulations covering the relevant parameters. The methods for LTB in Eurocode 3 are briefly presented and assessed. Despite the large scatter of results, the conservative nature of the "General Case" design rule was confirmed. The "Special Case" systematically led to significantly lower safety levels. A new Ayrton-Perry-based method was also assessed and it was shown to provide good accuracy. The magnitude of the partial factor γM1 * is addressed, whereby a good homogeneity of results is observed across the different buckling curves, with maximum variations of 0.05, except for the "Special Case", which systematically presents higher factors for most of the subsets. The "General Case" presents the lowest partial factors, but is clearly over conservative, leading in many cases up to 40% lower resistance. The γM1* values are compared for the "General Case" and the new Ayrton-Perry method with the results obtained for the flexural buckling resistance of columns. It is concluded that the partial factors for LTB are generally lower than those for flexural buckling.