Experimental and numerical study on seismic behavior of a self-centering railway bridge pier

This study mainly focuses on experimental and numerical investigation of the isolation mechanism and seismic performance of a self-centering railway bridge pier. To begin, a 1/25 scale typical self-centering railway pier model was designed and constructed, which consisted of a gravity pier, a spread foundation and a pedestal. The gravity pier was rigidly connected to the spread foundation, which was then directly seated at the top of the pile cap to allow the uplift of the pier during strong earthquakes. The model was tested in a pseudo-static manner under constant axial load and cyclic lateral load to characterize its seismic performance. It was found that the lateral load, the bending moment at the pier bottom, and the width of compression zone at the bottom of pier remained essentially constant when the uplift reached a certain extent. The hysteretic curves were in inverse 'Z' shape with narrow loops indicating good self-centering effect but poor energy dissipation. This means that the lateral force-displacement relationship of this type of piers can be simplified as an elasto-plastic curve and they should be used along with additional energy-dissipation devices. Upon the test results, a two-spring model was proposed and developed in the OpenSees platform to represent the test model, which was analyzed using the test load history. The results indicate that the two-spring model can simulate the pseudo-static test with high precision. This modeling technique hence can be employed to analyze seismic response of this type of bridge piers.