Inelastic behaviour of I-shaped aluminium beams: numerical analysis and cross-sectional classification

Abstract

In this paper, the results of an extensive numerical analysis program devoted to the evaluation of the inelastic response of I-shaped aluminium alloy beams in non-uniform bending are presented. By using a numerical model implemented in the implicit FE code ABAQUS/Standard and largely calibrated with experimental tests, the main geometrical and mechanical parameters influencing the plastic behaviour of such beams are investigated. The results obtained in this study confirm the important role of the material hardening which, in addition to the local slenderness of compressed elements, has a strong influence on both ultimate moment and rotational capacity of the member. Moreover, it is shown that the influence of the other parameters, namely flange-to-web slenderness ratio, moment gradient, web slenderness and sectional area ratio, on the plastic capacity of the considered beams in terms of strength and deformability is of a secondary importance even if it is not negligible. On the whole, the results, which are obtained for two different tempers, emphasize the need to improve the present guidelines provided by the European code for aluminium structures relating to cross-sectional classification. More accurate class limits for outstand elements, which are able to account for the most important influential parameters on the plastic behaviour, are therefore proposed.