This study assesses the seismic responses of viaduct structures in the Japanese high-speed rail system under moderate earthquake forces considering the slip between tracks and wheels. Equations of motion for the train–bridge interaction system were derived, where the track–wheel interaction was described by the Coulomb friction law. A full train–bridge finite element model incorporating nonslip and stick–slip interaction models was built using commercial finite element analysis software: abaqus. Simulation results indicate that the slip phenomenon might occur under a moderate earthquake and that a conventional nonslip model with an infinitely large friction coefficient is inappropriate. A parametric study revealed that the braking-train-induced slip friction little influenced the bridge response to moderate earthquake forces. The bridge's dynamic motions were dominated by ground motion irrespective of the values assigned as the train's initial speed and track–wheel friction coefficient. A computationally efficient method was proposed for calculating the longitudinal seismic responses of a bridge interacting with a braking train, following the linear superposition principle. As illustrated, this method could be helpful in reliability or uncertainty analysis when a great number of computationally expensive seismic analyses are required for train–bridge interaction systems.