Finite element modelling procedures for innovative built-up cold-formed beams

The numerical investigations of built-up cold-formed beams involve the use of advanced modelling techniques for predicting both their bearing capacity and post-buckling behaviour. In this case, in fact, the non-linear structural response can be influenced not only by geometric and mechanical imperfections, which are typical of thin-walled members, but also by contact interactions. With this regard, it can be noticed that the use of contact elements in finite element analyses could not allow the usual methodologies for modelling geometric imperfections to be applied, such as the linear superposition of mode shapes calculated through the elastic buckling analysis, and alternative approaches should be employed. In this paper, starting from the non-linear modelling of material and connections, an advanced methodology of analysis is proposed for the assessment of the load bearing capacity of built-up beams which takes into account both geometric imperfections and contact interactions. Such method, whose reliability must be validated against experimental tests, has been applied for the simulation of the structural behaviour of innovative of cold-formed beams.