Seismic Performance of Bridges with Rocking Piers in Hanshin Expressway

In April 2016, an earthquake of magnitude 7.3 occurred in Kumamoto Prefecture in Japan. Due to the strong tremor, a bridge with rocking piers collapsed. The rocking piers have pivot bearings both on top and bottom ends. As this structure is designed to only support vertical force, once the horizontal displacement occurs, the whole bridge structure would become unstable. In this study, one of same rocking pier bridges in Hanshin Expressway is focused on for seismic stability. Firstly, dynamic analysis for the whole bridge is carried out, and based on the results the retrofitting design is proposed. In the study, it is found that the reaction force of the existing bridge deduced significantly after the retrofitting. The dynamic analysis made after retrofitting proves that the response values of the entire bridge system remains unchanged.