A steel-concrete composite beam model with partial interaction including the shear deformability of the steel component

This paper presents an analytical model for the analysis of steel–concrete composite beams with partial shear interaction including the shear deformability of the steel component. This model is obtained by coupling an Euler–Bernoulli beam for the reinforced concrete slab to a Timoshenko beam for the steel beam. The composite action is provided by a continuous shear connection which enables relative longitudinal displacements to occur between the two components. The balance conditions are derived using the principle of virtual work and the weak form of the problem is presented. The steel of the beam and the steel of the slab reinforcement are modelled by using linear elastic laws, while the timedependent behaviour of the slab concrete is included by using a general linear viscous–elastic integral-type constitutive law. The numerical solution is obtained by means of the finite element method implementing a time-stepping procedure. The derived displacement-based finite elements are tested and their performance is discussed. Extensive numerical simulations are carried out on approximately 200 realistic simply supported and three-span 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 to determine under which conditions shear deformations of the steel component need to be considered in the analysis of composite systems and to evaluate how these are affected by the shear connection stiffness and by the redistributions due to the time-dependent behaviour of the concrete slab.