Computational study of failure of hybrid steel trussed concrete beams

This study investigates the failure behavior of hybrid steel trussed concrete beams (HSTCBs) under three-point bending through a series of finite-element (FE) simulations. The FE model employs well-established constitutive relations of concrete and steel with a simplified contact condition between the concrete and steel truss. The numerical model is compared with existing experimental data as well as a FE model that uses a more sophisticated concrete-steel interfacial model. The comparison shows that the present model is able to capture various failure mechanisms of the beam and its peak load capacity. The model is applied to investigate the behavior of a set of HSTCBs of different sizes, whose design corresponds to current industrial practice. The simulations show that, due to the lack of three-dimensional geometrical similarity, the small-size beam exhibits shear failure, whereas the large-size beam experiences flexural failure. The observed transition between different failure modes indicates the importance of employing a robust three-dimensional FE model for design extrapolation of HSTCBs across different sizes and geometries.