Abstract: In order to investigate the influence of the structural parameters of the reinforced concrete piers reinforced with ultra-high performance concrete(UHPC)on the seismic performance of the piers, based on the results of the proposed static test of the piers, the finite element model of the piers was established by using the ABAQUS. Based on the test data, the accuracy of the finite element model of the pier was verified, and the structural parameters such as the height of the reinforcement layer, the thickness of the reinforcement layer, and the reinforcement of the pier were analyzed using the control variable method. The results of the research showed that with the increase of the height of the reinforced layer UHPC, the plastic damage of the pier body decreased, which positively affected the improvement of the pier body's ability to resist the initial deformation and flexural load capacity. Under a certain thickness of reinforcement layer, the constraining effect of the abutment reached a saturation state, where further increasing the thickness of the UHPC reinforcement layer did not significantly affect the damage to the abutment or any related indicators. The increase in longitudinal reinforcement strength significantly impacted the seismic performance of bridge piers reinforced with UHPC, notably enhancing the pier's horizontal flexural capacity to a greater extent, while concurrently reducing the displacement ductility coefficient of the pier body. The overall development trends of bridge pier skeleton curves were similar for different strengths of longitudinal reinforcement. Substituting equal strength or equal volume with high-strength longitudinal reinforcement delayed the overall stiffness degradation of the pier body, thereby enhancing the elastic working capacity of the bridge pier.

Key words: UHPC, high-strength reinforcement, seismic strengthening, quasi-static test, parametric analysis