Effects of friction-based fixed bearings on the seismic vulnerability of a high-speed railway continuous bridge

The fixed bearings of high-speed railway continuous bridges were vulnerable during earthquakes, since they transferred most of the seismic force between the superstructure and the piers. A type of friction-based fixed bearing was used and would slide during strong earthquakes. The influence of this sliding friction action on the seismic vulnerability curves of different components in the track-bridge system was analyzed in this article. Results show that the sliding friction action of the fixed bearings can protect other components from severe damage under earthquakes. This phenomenon is more significant when the friction coefficient on the friction-based fixed bearings is reduced. However, it increases the seismic relative displacement of the fixed bearings themselves. Finally, a sufficiently large displacement capacity and an appropriate friction coefficient between 0.2 and 0.3 are almost the best combination for the friction-based fixed bearings, which can effectively protect all components of the track-bridge system, including the track structure, piers, piles, and friction-based fixed bearings themselves.