Derailment of high-speed trains moving on curved and cant rails under seismic loads

In this research, a finite element model was developed to simulate the derailment of trains moving on curved bridges during earthquakes, where the railway includes straight-line, clothoid, and circular sections. A train with 12 cars, 24 bogies, and 96 wheels was modeled using the moving wheel axis elements, spring-damper elements, rigid links, and lumped mass, where the elements included the curved motion capacity as well as the sticking, sliding, and separation modes of the wheel and rail contact. The finite element results showed that the maximum derailment coefficients of trains moving on curved bridges are larger than those of trains moving on straight-line bridges because centrifugal forces may enlarge the horizontal forces between the wheels and rails. Trains moving on curved bridges with and without lead rubber bearings (LRBs) were also simulated, and the results indicated that LRBs can greatly reduce the derailment coefficients of trains moving on curved bridges because they can decrease the two-way seismic ground accelerations transferred to superstructures. In addition, the LRBs at both ends of the girder support and reduce both lateral and longitudinal forces. This is the major advantage of LRBs in curved bridges in terms of reducing seismic vibrations transferring from bridge foundations. It is also pointed out that an appropriate cant angle is useful to avoid the derailment of trains during earthquakes.