Due to the setting of expansion joints, it will increase the impact force when the vehicle passes through, leading to the structural damage or pavement damage of the assembled bridges at the joints, which is a relatively common phenomenon in many bridge structures. In this paper, starting from the ontological relationship under damage mechanics, combined with the theory of continuous medium thermodynamics, we explore the damage evolution equations in a general sense. Then, based on ANSYS finite element software, the elastic-plastic damage model and the intrinsic model of the expansion joints of assembled bridges are established, and the meshing and boundary conditions are set. The finite element simulation results show that when the load is applied to 1179.71KN, the reinforcement at the tap expansion joints starts to yield, and at this time, the sectional bending moment is 959.67KN·m, and there are differences in bearing capacity and deflection of assembled bridges with different materials. Under the standard axle load of 120kN, the maximum principal compressive stress of the material does not exceed 4.5MPa. In order to better enhance the performance of the assembled bridge tap expansion joints, an external T-beam can be used to enhance its stress bearing capacity and prevent deformation.
