# Longitudinal Seismic Response of Continuously Welded Track on Railway Arch Bridges
## 1 Introduction  
The technology developed for continuous welded rail (CWR) on bridges is one of the core technologies in modern railway tracks, providing support for high-speed and heavy load railway transportation [1; 2; 3]. However complicated operation environments and potential natural hazards provide challenges to railway safety and long-term reliable operation. In cases of earthquake damage from across the globe, railway have suffered varying degrees of damage [4; 5; 6; 7]. The impact of earthquakes on CWR on bridges has thus gradually attracted increased attention. According to previous research (based on longitudinal track-bridge interactions), the rail longitudinal force (which is closely related to line stability, rail bar design, rail creep, and the track safety) under seismic loading is several times larger than that resulting from temperature changes. Therefore, the effect of seismic on track-bridge longitudinal response should be considered when designing CWR on bridges in seismically active zones. In existing research on the seismic response of CWR on bridges, the natural vibration characteristics and seismic response of the bridge were shown to be affected by the longitudinal restraint of the track. [PERSON] et al. conducted numerical analyses to assess the effect of the track structure on the seismic behavior of an isolated bridge, and the results proved that supplemental damping introduced by the track structure is not negligible [8]. [PERSON] et al. tested natural bridge frequency and the effects oftrack structure on the dynamic characteristics of the bridge. The test results show that when the track structure exists, the vibration transfer from rail to embankment is more obvious. After cutting off the rail, the fundamental longitudinal, horizontal, and vertical frequency of the entire bridge structure are reduced [9]. The seismic responses of continuously welded ballasted track on bridges through the shaking table test were conducted, and the results indicated that track constraint can improve the low order natural frequency of bridges significantly, and reduce the displacement response [10]. [PERSON] analyzed the seismic response of high-speed railways on small span simply-supported beam bridges [11]. [PERSON] developed a finite element model for a seismic analysis of ballasted railway track, and the ballast layers were modeled using a series of lumped masses connected by springs and dashpots to simulate the ballast longitudinal resistances [12]. [PERSON] et al. [13] analyzed the earthquake excitation response of multi-span ballasted track supported by simply beam bridges via the plain, V-valley, and slope areas. The results showed that the nonlinear interaction between the beam and track must be considered when it comes to railroad bridge seismic response analysis. [PERSON] [14] simulated the rail-structure interaction of a ballasted track when subject to a train braking load and a seismic load. [PERSON] et al. [15] analyzed the seismic response of simply supported beam bridges under different bearing stiffness conditions. The results showed that after considering the rail constraints, the fixed support displacement can be reduced 30-60%, while the greatest rail axial force is much lower than the critical value of the loss of stability. [PERSON] et al. [16] designed and implemented the shaking table model test in the laboratory to study the effect of track restraints on bridge seismic response. Published research reveals that the stress deformation mechanism of CWR track on large-span arch bridges is complex and quite different from that of simply supported beam bridges and continuous beam bridges. However, previous work on track-bridge interaction under uniform seismic excitation mainly focuses on the seismic response of simply supported beam bridges and continuous beam bridges. It fails to fully account for the seismic response of CWR track on large-span arch bridges.