Experimental and numerical investigation of channel shear connectors in steel deck composite slabs

The use of channel shear connectors in composite slabs and beams offers logistical and mechanical advantages over headed studs, making them suitable for structures under complex loading. However, standard prediction models are primarily developed for solid concrete slabs, limiting their applicability to composite slabs with steel decking. This paper investigates the influence of steel decking on channel connector shear resistance through push-out tests on two solid slab (SS) specimens and three composite slab (CS) specimens with varying configurations, analyzing the effects of deck thickness and rib reinforcement. Experimental results showed that CS specimens exhibited 2.5 times lower shear resistance and four times less ductility than SS specimens, with failure modes shifting from web base rupture in SS specimens to concrete cone failure in CS specimens. Rib reinforcement within the steel deck improved shear resistance and ductility, while increased deck thickness provided minor gains but slightly reduced stiffness. Prediction models accurately estimated SS specimen resistance but were imprecise and unconservative for CS specimens. A numerical study was conducted, consisting of a calibration phase and a parametric investigation. The calibration phase analyzed factors such as slab-support friction, steel-concrete friction, and weld representation. Slab-support friction was the most influential, with low values underestimating shear resistance due to excessive slip, while weld modeling affected stiffness and deformation differently for SS and CS specimens. The parametric study examined reinforcement configuration, connector height, concrete cover thickness, and concrete strength. Results showed that increasing connector height significantly improved load capacity and ductility, while concrete cover thickness had a greater effect when failure was governed by connector rupture. Different reinforcement configurations produced slight variations in performance, with double reinforcement offering marginal gains. Increasing concrete strength enhanced load capacity, though its effect on slip varied depending on the failure mode. Based on these findings, optimized correction factors were derived to refine predictive load capacity models paired with reduction coefficient equations for stud bolts, enhancing their applicability to composite slabs with channel connectors for the parameters assessed.