Concentrated approaches for nonlinear analysis of composite beams with partial interaction

Abstract

Two plane displacement-based formulations with concentrated nonlinear effects for numerical analysis of composite beams are presented here. The effects of geometric nonlinearity, plasticity and partial shear connection are considered. In these two approaches, the co-rotational system is defined to allow large displacements and rotations in the numerical model. The first formulation is based to Strain Compatibility Method, where the sections strains are explicitly evaluated as well as the slipping at the steel-concrete interface. Thus, the axial and flexural stiffness of the cross section is determined in each step of the incremental-iterative process. The second methodology considers rotational pseudo-springs at the finite elements ends to simulate of plasticity. Furthermore, the effects of partial interaction can not be simulated by the inherently rotational behavior of the pseudo-springs. Thus, the cracking and partial interaction effects are approached through effective moment of inertia defined by normative criteria. Four composite beams are simulated with these two formulations and compared by the load-displacements paths. In all numerical result findings these formulations are closed and accurate to the experimental data presented in literature.