Parameter study of a steel-reinforced rubber bearing-supported quasi-isolated continuous girder bridge

To enhance the seismic performance of steel-reinforced rubber bearing beam bridges, this paper proposes a quasi-isolation system to address two critical limitations: inadequate displacement-limiting capacity and compromised self-centring capacity. In the OpenSees software platform, a refined finite-element model of a four-span continuous beam bridge was established. Based on seismic responses such as girder beam displacement and pier internal forces in bridge piers, this paper analyses the mechanical parameters of mild steel blocks and viscous dampers. The results indicate that when the mild steel blocks are designed with a yield strength equivalent to 20% of the bearing reaction force, an initial stiffness corresponding to a yield displacement of 0.01 m and a post-yield stiffness ratio of 0.08, they can effectively control the lateral displacement of the main girder, substantially reduce post-earthquake residual displacement and reduce the force and displacement demands on the bearings. For viscous dampers with a damping exponent α of 0.4, they can, to a certain extent, reduce the maximum and residual displacements at the girder ends while significantly decreasing the internal forces in the piers. For the investigated bridge, the proposed arrangement improves displacement control and reduces the seismic force demand on the piers under the adopted analysis conditions.