Failure mode and strength prediction of laterally braced Litzka-type castellated beams

Abstract

The present paper aims to investigate the failure modes of laterally braced non-composite Litzka-type castellated beams using finite element simulations, evaluating aspects such as mutual influence of the constituent parts to the behavior, interaction of individual modes and post-buckling reserve of strength. For a comprehensive analysis, a parametric study is carried out and the behavior is depicted in a plot (‘map’) in terms of the bending moment-to-shear force ratio, the flange and web geometries and the generalized non-dimensional slenderness depending on the plastic and buckling loads. It is shown that the failure mode of a certain beam can be roughly predicted according to the region of the ‘map’ it belongs. The results confirm the occurrence of interaction between individual modes and reveal that the normalized strength decays more quickly with slenderness for shear-dominated failure, although some post-critical reserve of strength can be observed. Finally, inspired by the Direct Strength Method, a design approach is proposed to assess the load carrying capacity of beams with usual geometries.