Strength Analysis of Steel–Concrete Composite Beams in Combined Bending and Shear

TLDR

Current design codes ignore the concrete slab and composite action contributions to vertical shear strength of simply supported steel–concrete composite beams, leading to conservative designs. This study investigates flexural and shear strengths of simply supported composite beams under combined bending and shear, examines how shear connection degree affects vertical shear strength, and proposes design models incorporating concrete slab and composite action for moment–shear interaction. A verified three‑dimensional finite element model accounting for geometric and material nonlinearities is employed to quantify concrete slab and composite action contributions to moment and shear capacities, study the effect of shear connection degree, and develop design models for vertical shear strength and ultimate moment–shear interaction. The proposed design models provide a consistent and economical procedure for designing simply supported composite beams.

Abstract

Despite experimental evidences, the contributions of the concrete slab and composite action to the vertical shear strength of simply supported steel–concrete composite beams are not considered in current design codes, which lead to conservative designs. In this paper, the finite element method is used to investigate the flexural and shear strengths of simply supported composite beams under combined bending and shear. A three-dimensional finite element model has been developed to account for geometric and material nonlinear behavior of composite beams, and verified by experimental results. The verified finite element model is than employed to quantify the contributions of the concrete slab and composite action to the moment and shear capacities of composite beams. The effect of the degree of shear connection on the vertical shear strength of deep composite beams loaded in shear is studied. Design models for vertical shear strength including contributions from the concrete slab and composite action and for the ultimate moment–shear interaction are proposed for the design of simply supported composite beams in combined bending and shear. The proposed design models provide a consistent and economical design procedure for simply supported composite beams.