Determination of mechanical properties of headed shear connectors in composite steel beams with precast concrete hollow core slabs: Experimental study

Precast concrete hollow core (PCHC) slabs are structural elements widely used in multistory long-span composite structures for their lightweight, cost-effectiveness, and guaranteed quality. In addition to ease of installation, PCHC slabs offer high acoustic and thermal insulation, as well as commendable fire resistance. In conventional composite beams with solid concrete slabs, the composite action is established via shear studs or other mechanical shear transfer mechanisms. Consequently, determining the shear strength and stiffness of the shear studs is necessary to quantify their composite behavior. However, few studies investigate the mechanical properties of the stud connectors in composite steel beams with PCHC slabs. This study addresses this gap by 11 full-scale push-out tests performed on specimens featuring 203- and 254-mm PCHC slabs connected to steel beam via 13- and 19-mm diameter connectors. The concrete compressive strength, slab thickness, shear stud diameter, and different shear stud layouts varied in the specimens. All specimens were tested to failure documenting the load-slip diagrams and the failure modes. Mechanical properties of the shear stud connectors were assessed based on the load-slip diagrams under monotonic and cyclic loadings. The result showed that the codified equations for estimating the shear capacity of studs in solid slabs underestimate the capacity of studs in PCHC slabs. Additionally, the shear capacity of shear stud connections was reduced about 15 % in the cyclic loading case compared to the monotonic.