Lateral-torsional buckling of cellular beams according to the possible updating of EC3

Abstract

Researchers have not yet reached a consensus on which buckling curve to use for the calculation of the lateral torsional buckling (LTB) resistance of cellular steel beams in the current version of EC3. In addition, there is a new proposal for the future update of EC3, in which the imperfection factor is a function of the elastic section modulus, as well as material imperfections. The aim of this study is to investigate the LTB resistance of cellular steel beams by modifying the distribution of residual stresses after the manufacturing process. Geometrical and material nonlinear analysis are performed using the software ABAQUS 6.12. The cellular steel beams are simply supported, with fork-supports at the end, and subjected to uniform bending, mid-span concentrated load and uniformly distributed loads. In the latter two cases, neutral and destabilizing effects of loading are considered. The results are compared to analytical procedures, international standards, and also, with the possible EC3 updating. It was concluded that the calculation prescription of the new proposal, considering the imperfection factor that meets the magnitude of the residual stresses after the manufacturing process of cellular steel beams, is effective, accurate and conservative for LTB resistance in inelastic and elastic behavior. However, for the case of stocky cellular steel beams, whose shear stress is preponderant, ultimate limit states, such as Vierendeel mechanism and web post buckling, must be verified first.