FEM simulations of lateral torsional buckling experiments on channel sections loaded in bending

The lateral torsional buckling behaviour of hot rolled channel sections subjected to bending is studied in an overall project. The final objective of this project is to develop a design method. This paper concentrates on the validation of the FEM model against the experiments. For channel sections loaded through the shear centre (centric loading) sudden collapse was observed while channel sections loaded in the plane of the web (eccentric loading) fail gradually in bending and torsion. The objective of the numerical research was to simulate this experimental behaviour and to predict the failure load correctly. Therefore, a FEM model was made consisting of shell elements and beam elements to compensate for the root radius of the channels, including plastic material behaviour, geometric non-linearity and measured imperfections. The simulations gave agreeable failure loads. For eccentric loading, the FEM simulations showed load-displacement curves, which compare well with experimental results. For centric loading however, the results appeared to be largely sensitive to imperfections with respect to member straightness. Finally, it is concluded that the FEM model is successfully validated against the available test results.