Large displacement analysis of thin-walled beams with generic open section

A finite element formulation for geometric non-linear analysis of elastic straight thin-walled beams is presented. The updated Lagrangian procedure is used for a stiffness matrix derivation-to analyse large displacements or buckling behaviour of space frames. The stiffness matrix is developed for a generic cross-section and is equally efficient for symmetric, monosymmetric or asymmetric open sections. Some non-linear strain terms usually neglected in the literature have been considered, resulting in a formulation which also includes the initial bimoment and torsion effect for all cross-sections analysed. The proposed method has been implemented and the results of sample problems are presented.