Analytical investigation on failure development of group studs shear connector in push-out specimen under biaxial load action

Arranging studs in group, referred to as group studs shear connector, has been applied in steel and concrete composite structures many years for its constructional efficiency. Nowadays, many long span composite bridges with group studs have been designed with wide transverse cantilevers and web spacing. The cantilever self-weight and passing-by moving loads thus make the studs under biaxial load action consisting of longitudinal shear force and transverse bending-induced action. The stud mechanical failure appearance and its development are not clear enough in this condition. In this case, we carried out a parametric push-out FEM analysis with introduced damage plasticity material models. In this study, effect of biaxial load action has been concerned in parametric models with different stud dimension and concrete strength. We found that biaxial load action could increase the stud shear stiffness and strength. And concerning push-out failure mode, the analysis showed that biaxial load action reduced concrete damage and resulted to a more obvious stud shear failure with less bending deformation. During the failure development, it tended to increase the capabilities of both stud and concrete of supporting local stress concentrations but slightly reduce the stud bending deformation extension. In addition, concrete strength and stud flexibility would affect the stud failure composition as well.