Efficient assessment of 3D train-track-bridge interaction combining multi-time-step method and moving track technique

This paper extends the 2D multi-time-step (MTS) method previously proposed by the authors to 3D train-track-bridge dynamic analysis for evaluating in detail the running safety and riding comfort of a train. The train-track-bridge coupled system (TTBS) is separated into the train subsystem, the track subsystem, and the bridge subsystem. These subsystems are coupled by the interaction forces between them. A fine time-step is adopted for the train subsystem and the track subsystem due to the high-frequency wheel-rail contact. A coarse time-step is adopted for the bridge subsystem due to its low-frequency vibration. To reduce the number of degrees of freedom (DOFs) of the track structure, a moving track technique is applied in this paper. The train-track-bridge coupled model with the MTS method is validated by comparing the numerical results with field measurement data of a cable-stayed bridge. A numerical simulation of a train traversing a long-span cable-stayed bridge is used to demonstrate the computational efficiency and accuracy of the proposed method. It is shown that the proposed method is accurate and computationally more efficient than using a uniform time-step for the TTBS.