Bond-Slip Push-Out Performance and Finite Element Analysis of Double-Fold Steel Plate Shear Connector

Steel-concrete composite structures have been more and more widely used in engineering due to their good mechanical properties; shear connectors are very important to ensure the joint stress of steel structures and concrete structures. A double-folded steel plate shear connector with flanges was proposed to obtain better bearing capacity and deformation. The push-out test for double-fold steel plate shear connectors was designed and carried out, and the mechanical properties of double-fold steel plate shear connectors and ordinary studs were compared and analyzed. Based on the push-out test results, a finite element model was established. The influence of parameters of folded plate height, thickness and opening diameter on the mechanical properties of shear connector was further obtained. The main conclusions were as follows: the double-folded shear connector showed semi-rigidity: compared with studs, the slip load was increased by more than 60%, and the ultimate bearing capacity was increased by about 50%. At the same time, it had better deformation and had a larger restraint area; the strain distribution of concrete restrained by double-fold steel plate shear onnectors was relatively uniform. Under the same loading condition, the strain value was smaller, indicating that the shear connector was better combined with the concrete slab, and the force transmission was more uniform. As the thickness of the folded plate increased, the ultimate bearing capacity of the shear connector was increased obviously, but its deformation did not change obviously. When the height of folded plate decreased to less than 80 mm, the bearing capacity was improved, but the deformation was reduced. The larger the opening diameter was, the lower the bearing capacity of the shear connector was, and the deformation showed a trend of increasing first and then decreasing; finally, a more reasonable design size of the double-fold steel plate shear connector was obtained: 6 mm thick, 80-90 mm high and 25 mm opening diameter.