Analysis of Steel–Concrete Composite Elements Considering the Branson Equation for Cracking Simulation

In the computational efficiency context, combining response precision and low execution time, methods that consider concentrated non-linear effects are interesting. The refined plastic hinge method (RPHM) considers the plasticity effects exclusively at the nodal points of the finite element mesh, however, it was developed for steel structures, with elastic-perfectly plastic behavior. In this methodology, rotational pseudo-springs in the finite elements ends are responsible to introduce the flexural stiffness degradation due to material non-linearity while the one-dimensional elements remain in the elastic state. The present work aims to study the inclusion of the flexural stiffness degradation of steel–concrete composite structural elements under monotonic loads, considering the cracking effects through the Branson equation, coupled to RPHM. For this, it is necessary to delimit the uncracked and cracked behavior of the cross-section. Thus, the strain compatibility method was used, in which, through the study of the cross-sectional behavior, interaction curves are obtained for the determination of elastic/elasto-plastic/plastic and uncracked/cracked states. Furthermore, this proposition is applied in a displacement-based formulation for the evaluation of the global behavior of steel–concrete composite elements. Comparisons are made between the results obtained here and those available in the literature, in the experimental and numerical contexts. These comparisons indicated for the validation of the numerical procedure proposed and implemented here, highlighting the precision of the formulation in both the pre- and post-critical structures behavior.