Theoretical and numerical stability analyses of unrestrained, mono-symmetric thin-walled beams

In this paper, a contribution to the overall stability of unrestrained thin-walled elements with open sections is investigated. A model is developed for beam lateral buckling stability analysis. According to the European steel code, Eurocode 3; an analytical solution is used for checking the stability of laterally unrestrained beams. It depends on bending distribution, on load height effect and on degree of the monosymmetry of the section called Wagner's parameter. Coefficients C-1, C-2 and C-3 are respectively affected to these parameters and are given for some selected load cases. Based on the present model, these coefficients are recomputed for simply supported beams. Ritz and Galerkin's methods are applied. Following Galerkin's method, the coefficients C-1 and C-2 are the same as those adopted in Eurocode 3, but some of Wagner's proposed C-3 coefficients are very different from those usually used. The different solutions are first discussed and then compared to finite element results. ABAQUS software is used in numerical simulations where three-dimensional beams with warping and shell elements are chosen in modelling lateral buckling phenomena. The presented results are close to shell element results but the regular solutions overestimate the lateral buckling resistance of mono-symmetric I beams. (C) 2002 Elsevier Science Ltd. All rights reserved.