The rail expansion joints (REJ) is an essential track component for relieving the interaction between bridge and CWR track on large-span bridge. In order to ascertain the expansion capacity of REJ in different seismic zones, based on the case study of a continuous beam bridge with span of 48 m+3×80 m+48 m in a certain passenger dedicated line, this paper established an REJ-bridge-piers calculation model considering the bridge-track interaction principle under the action of earthquake, and analyzed the influence of seismic wave spectral characteristics, the traveling wave effect, the friction coefficient of movable support, the REJ arrangement and location and the acceleration amplitude of seismic wave on the expansion amount of REJ. The results showed that the effect of earthquake on the expansion amount of REJ is considerable. The earthquake effect should be considered during the determination of the expansion capacity of REJ and the additional expansion amount of REJ should be considered to guard against low-level earthquakes. The expansion amount of REJ was influenced by the seismic wave spectral characteristics. The wider the wave frequency range and the stronger the wave amplitude, the bigger the expansion amount of REJ was. Under the action of earthquake, with the decrease of propagation velocity of earthquake, friction coefficient of movable support, and the increase of acceleration amplitude of seismic wave, the maximum value of expansion amount of REJ increased significantly, while the impact of seismic wave velocity was significant. The laying position of REJ also posed a great impact on the expansion amount of REJ in earthquake. The REJ should be laid as far as possible from the beam seam on condition that force requirement and other requirements are all satisfied. The recommended values of the additional expansion capacity of REJ under different seismic fortification intensity levels for Class I and Class II sites were all ascertained respectively. The recommended values for Class II site are about twice of Class I site under the same seismic fortification intensity. © 2016, Editorial Office of Journal of the China Railway Society. All right reserved.
