Abstract
To explore the effect of canyon topography on the seismic response of railway irregular bridge–track system that crosses a V-shaped canyon, seismic ground motions of the horizontal site and V-shaped canyon site were simulated through theoretical analysis with 12 earthquake records selected from the Pacific Earthquake Engineering Research Center (PEER) Strong Ground Motion Database matching the site condition of the bridge. Nonlinear seismic response analyses of an existing 11-span irregular simply supported railway bridge–track system were performed under the simulated spatially varying ground motions. The effects of the V-shaped canyon topography on the peak ground acceleration at bridge foundations and seismic responses of the bridge–track system were analyzed. Comparisons between the results of horizontal and V-shaped canyon sites show that the top relative displacement between adjacent piers at the junction of the incident side and the back side of the V-shaped site is almost two times that of the horizontal site, which also determines the seismic response of the fastener. The maximum displacement of the fastener occurs in the V-shaped canyon site and is 1.4 times larger than that in the horizontal site. Neglecting the effect of V-shaped canyon leads to the inappropriate assessment of the maximum seismic response of the irregular high-speed railway bridge–track system. Moreover, engineers should focus on the girder end to the left or right of the two fasteners within the distance of track seismic damage.
Highlights
With the development of western regions in China, railway construction is gradually extending to the complex topography and high seismic intensity areas of the southwest mountainous area, and the risk of high-speed railways suffering from earthquakes in the mountainous area is increasing [1, 2]
The seismic analysis of the railway bridge–track system built on the mountainous topography needs to consider two negative effects: (i) the dynamic characteristics and seismic responses of adjacent spans of irregular bridges are different due to various topographies [3, 4]; (ii) the spatial variability effect of ground motion distribution caused by local site and irregular topography leads to different parameters of ground motion excitation at different pier locations [5–7]
Excluding the spatial variability of ground motions in the canyon topography may lead to improper estimation of the seismic responses of the high-speed railway bridge–track system, which highlights the great importance of analyzing the effect of canyon topography on the seismic performance of the bridges located in the V-shaped canyon
Summary
With the development of western regions in China, railway construction is gradually extending to the complex topography and high seismic intensity areas of the southwest mountainous area, and the risk of high-speed railways suffering from earthquakes in the mountainous area is increasing [1, 2]. Some other researchers [4, 33] carried out nonlinear dynamic analysis studies on the CRTS-II track system on the irregular bridge based on the uniform seismic input They found that the track structure on the bridges with unequal height piers is more prone to earthquake damage than the bridges with equal height piers. It is necessary to study the impact of spatially varying ground motions caused by topography effects on the seismic damage of ballastless track on irregular supported beam bridges in mountainous topography. The seismic responses of the example bridge under the simulated ground motions from different topography models are analyzed to reveal the effect of V-shaped canyon topography on the seismic performance of irregular high-speed railway bridge–track system
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