Shear Performance and Optimization Design of Beam-Slab Connector of Prefabricated Steel–Concrete Composite Structures

In this study, we designed a novel shear connector for steel–concrete composite structures, which is referred to as the prefabricated weld-nut bolt (PWNB). Three steel–concrete composite specimens using PWNB connectors were fabricated, and the same number of specimens using shear studs were used in a control group. Push-out test was carried out on the specimens. The load–displacement curve, the bearing and deformation capacity, and the failure form were analyzed. Then, a three-dimensional finite element model was established to verify the validity of the model. Combined with the test results, the actual mechanical condition of the PWNB connector inside the concrete slab was obtained. The experimental and numerical results demonstrated the advantages and disadvantages of the proposed PWNB shear connector. Further, based on the above results, targeted optimization of the PWNB connector was carried out, and the feasibility of the optimization scheme was validated by the extensibility analysis based on numerical simulation. By changing the concrete strength and the width of the welding nut, nine models with optimized PWNB connectors were compared, and parametric analysis was carried out. The results showed that the PWNB connector no longer occurs yielding strain prematurely due to the irregular section of thread. By adjusting the size of welding nut to a reasonable value, the structural advantages of the PWNB connector after optimization became more prominent, which can serve as an economical and reasonable option for improving the shear performance of steel–concrete composite structures.