Strength and Failure Behaviour of Welded Rebar Shear Connectors in Composite Beam with Solid Concrete Slab

Shear connectors play a vital role in facilitating composite action between the supporting steel beam and concrete slab. This paper explores rebar shear connectors' strength and failure behaviour within solid concrete slabs. The developed finite element model accurately predicted the ultimate shear capacity with the experiment. The average ratio of numerical to experimental predicted load capacity was 1.0 (ranging from 0.76 to 1.2). The FE model was capable of predicting similar failure behaviour observed during experiment. Additionally, the validated FE model was employed to conduct an extensive parametric study. The influence of both rebar strength and concrete grade on the shear performance of rebar connectors with diameters of 16, 20, 25 and 32 mm was evaluated through a detailed parametric analysis. This investigation incorporated concrete strengths of 30, 40 and 50 MPa to assess their impact on connector behaviour. Additionally, the connector strength was varied among 275, 415 and 500 MPa. Higher strength bars exhibit better ductile behaviour compared to lower strength bars. Increasing the concrete compressive strength from 30 to 50 MPa led to an approximate 40% enhancement in the shear capacity of 25 mm diameter rebar connectors with a yield strength of 500 MPa. The effect of increased concrete strength was more pronounced in larger diameter rebars with higher yield strength, which showed greater gains in shear resistance compared to smaller diameter connectors with lower-grade steel. Drawing from the results of 33 parametric push-out simulations, a modified design equation, derived from the AISC 360-16 formulation for headed stud connectors is proposed to estimate the ultimate shear strength of rebar shear connectors embedded within solid concrete slabs.