An experimental and numerical study for local behaviour of steel-concrete composite structures with novel long-nut shear connectors

An experimental and numerical study on the behaviour of the steel-concrete composite structure with the novel shear connectors has been conducted in this paper. The new bolted connector consists of a long tube nut and a compatible partial-thread bolt. The nut is casted in concrete and the bolt is connected to the nut through pre-drilled holes in the steel beam to achieve the interaction between the concrete slab and the steel beam. The push-out specimens have been designed and manufactured. The push out tests are carried out to investigate the stiffness, strength, and ductility of the new connectors in concrete and the results are compared with that using conventional welded connectors. A finite element model is established and validated using experimental results. With the validated finite element models, the effect of the concrete strength, the shear connector diameter, the bolt pretension, the gap between the bolt hole and bolt, and the nut diameter on the local behaviour of shear connectors are analysed and discussed. The results show that the novel bolted shear connectors have superior ultimate load capacity and ductility compared to conventional welded connectors. This novel bolt connection could also achieve the equal shear resistance in all directions and reduce the stress concentration in the tangible medium.