Effects of the shear deformability of the steel member in the short- and long-term partial interaction analysis of steel-concrete composite beams

This paper presents an analytical model for the short- and long-term analysis of steel-concrete composite beams with partial shear interaction due to the deformability of the shear connectors. Its particularity relies on its ability to depict the shear deformability of the steel component. The time-dependent behaviour of the concrete is described by means of the integral type creep law and is implemented in the analysis using the step-by-step procedure. The steel of the reinforcement and joist are assumed to remain in the linear-elastic range. These material representations are assumed to be appropriate at service conditions. The analytical model is derived by means of the principle of virtual work and the numerical solution is obtained using the finite element method. Extensive numerical simulations are carried out on realistic simply supported composite beams to evaluate the effects of the shear deformability of the steel member on the overall structural response. The numerical results obtained with the proposed model are compared to those of the composite beam model with partial shear interaction that does not include the shear deformability of the steel beam in order to (1) de-termine under which conditions shear deformations of the steel component need to be considered in the analy-sis of composite systems; (2) evaluate how these are affected by the shear connection stiffness and by the re-distributions due to the time-dependent behaviour of the concrete slab.