New method for metal beams sensitive to lateral torsional buckling with an equivalent geometrical UGLI imperfection

Abstract

[EN] The Eurocodes EN 1993-1-1:2005, prEN 1993-1-1:2020, and EN 1999-1-1:2007, prEN 1999-1-1:2020 propose the same method. They take into account the geometrical equivalent Unique Global and Local Initial (UGLI) imperfections. According to the Eurocodes, the assumed shape of UGLI imperfections may be derived from the elastic buckling mode and provide a method that enables computing the amplitude of a UGLI imperfection in slender metal structures. The authors method presented enables computing the amplitude of the initial imperfection for the lateral torsional buckling of beams with a doubly symmetric section. This is a generalization of Eurocode rules that is valid only for members in compression. Numerical examples are presented in order to understand the authors method. The buckling resistance is verified with the test of Wieschollek et al. and compared with the results of four other authors, the results of a Geometrically and Materially Non-linear Analysis (GMNIA) with imperfections and the results of other methods used in the current Eurocode 3 and a draft of its new generation.