Headed steel stud connectors for composite steel beams with precast hollow-core slabs with structural topping

• An expression to predict the shear strength of headed stud connectors with hollow-core slabs is proposed.
• This expression differs from other studies due to the presence of a structural concrete topping on the hollow-core slabs.
• Standard push-out tests for solid slabs were adapted to hollow-core slabs.

Composite beams of steel and concrete have been studied for a long time. The transfer of longitudinal shear stresses at the interface between the beam and the slab is a key point in obtaining the composite beam behaviour, which is usually achieved by means of shear connectors. In this case, the joint behaviour of the two materials depends on the strength and stiffness of the interface connector. Headed stud connectors for solid concrete slabs are the most common solution to achieve the composite behaviour. However, there is little information on shear connectors associated with precast concrete hollow-core slabs. This study aims to determine, through push-out tests, the shear strength of headed stud connectors associated with precast hollow-core slabs with a structural concrete topping. The analysed hollow-core slabs have two different heights and a minimum structural concrete topping of 40 mm. The strength of the in situ concrete infill joints and the rate of transverse reinforcement were varied in the present study. The results were compared to code prescriptions, and a proposition to modify an existing design equation for the ultimate shear capacity of headed studs in composite precast hollow-core slab beams is presented, focusing on the influence of the structural concrete topping.