Modelling of the behaviour of a thin-walled channel cross section, using beam finite elements

This paper aims at presenting an approach allowing studying the behaviour of channel profiles through the use of beam finite elements. This approach can be considered as an interesting alternative to the use of plate finite elements, for the modelling of structures made of thin-walled members. The main idea consists in superimposing on a classical beam global displacement field, a local field describing the deformation of the profile cross-section, when a local buckling or a distortional buckling occurs. In a first step, the behaviour of the constitutive walls of a profile is studied. These walls are there considered as single plates. Two main classes of walls are studied (internal walls, such as web, and free edge walls, such as flanges). Different kinds of stress state are also considered, in order to be able to model the behaviour under compression and/or bending. In a second step, these isolated wall models are assembled in order to build up a channel section profile. The approach is applied to the computation of critical buckling load under compression and in-plane bending.