Quasi-static testing of rocking piers for railway bridges

Rocking piers are increasingly recognized as a viable seismic isolation strategy for bridges. Compared to highway bridges, railway bridges are subjected to more stringent requirements for post-seismic functional recovery due to the elevated operational standards of train travel. Conventional rocking piers, however, encounter significant challenges. This study presents a rocking pier system specifically designed for railway bridges, with its feasibility confirmed through quasi-static testing. The test results demonstrate that incorporating rocking resilient hinges (RRHs) at the rocking interface enhances the rotational stability of the piers. The RRHs and horizontal limiting devices provide the pier with a nearly constant center of rotation during the rocking phase. This configuration effectively mitigates the inaccuracies typically associated with predicting the compressed area height of conventional rocking interfaces, significantly enhancing the predictive accuracy of the piers' behavior during and after earthquakes. An enlarged steel plate mounted on the top surface of the RRH assists in stress distribution, effectively preventing localized concrete damage and reducing repair costs following seismic events. In addition, the system's replaceable external energy dissipation devices facilitate rapid post-earthquake recovery. By embedding continuous unbonded prestressed tendons within the pier and coordinating with an enlarged base, the rocking interface remains closed under normal operational conditions or during frequent earthquakes, ensuring uninterrupted train functionality. The system's 'locking' mechanism is a final safeguard, fulfilling critical life safety objectives.