Mechanical Properties of Stud Connectors in Composite Beams with Precast Concrete Hollow Core Slabs

Composite steel beams with precast concrete hollow core (PCHC) slabs are widely used to construct multistory long-span structures. PCHC slabs are commonly manufactured by extrusion or slip-formworks using concrete with very low workability. Initially provided with circular voids, their sections have been improved in the last decades using a kind of ellipsoidal voids and pre-stressed concrete. Compared to solid concrete slabs, PCHC slabs are more light-weighted, cost-effective, easy to install, fire resistant, and have better thermal insulation. Shear connectors ensure the longitudinal shear transfer between the concrete slab and the steel beam in conventional composite beams with solid concrete slabs. In order to quantify the composite behaviour between the steel beam and the concrete slab, it is of great importance to determine the shear stud stiffness and strength values. However, limited studies investigate the mechanical properties of the shear studs in composite beams with PCHC slabs. This paper conducted pushout tests on five full-scale composite beams of 254 mm depth PCHC slabs connected to the steel beam via 19-mm diameter connectors. The shear stud configurations were varied. The effect of cyclic loading on the failure mode was studied. The shear stud strength and loadslip diagrams were investigated by varying the compressive strength of the concrete cover under monotonic and cyclic loading. Also, a finite element (FE) model was developed and calibrated based on the experimental results. The parametric FE analyses were performed to investigate the effect of the shear stud diameter and concrete compressive strength on the shear stud capacity. The experimental and numerical study results showed that the specimens with a three-shear stud layout performed better than those with a two-shear stud layout. Also, the cyclic loading resulted in a 15% lower maximum shear stud capacity than the corresponding monotonic loading.