Abstract
To explore the influence of spatially varying ground motion on the dynamic behavior of a train passing through a three-tower cable-stayed bridge, a 3D train–track–bridge coupled model is established for accurately simulating the train–bridge interaction under earthquake excitation, which is made up of a vehicle model built by multi-body dynamics, a track–bridge finite element model, and a 3D rolling wheel–rail contact model. A conditional simulation method, which takes into consideration the wave passage effect, incoherence effect, and site-response effect, is adopted to simulate the spatially varying ground motion under different soil conditions. The multi-time-step method previously proposed by the authors is also adopted to improve computational efficiency. The dynamic responses of the train running on a three-tower cable-stayed bridge are calculated with differing earthquake excitations and train speeds. The results indicate that (1) the earthquake excitation significantly increases the responses of the train–bridge system, but at a design speed, all the running safety indices meet the code requirements; (2) the incoherence and site-response effects should also be considered in the seismic analysis for long-span bridges though there is no fixed pattern for determining their influences; (3) different train speeds that vary the vibration characteristics of the train–bridge system affect the vibration frequencies of the car body and bridge.
Highlights
High-speed railways (HSR) have played an increasingly important role in solving traffic problems in many countries [1, 2], especially for China, which has the largest population in the world
To explore the influence of spatially varying ground motion on the dynamic behavior of a train passing through a three-tower cable-stayed bridge, a 3D train– track–bridge coupled model is established for accurately simulating the train–bridge interaction under earthquake excitation, which is made up of a vehicle model built by multi-body dynamics, a track–bridge finite element model, and a 3D rolling wheel–rail contact model
The results indicate that (1) the earthquake excitation significantly increases the responses of the train–bridge system, but at a design speed, all the running safety indices meet the code requirements; (2) the incoherence and site-response effects should be considered in the seismic analysis for long-span bridges though there is no fixed pattern for determining their influences; (3) different train speeds that vary the vibration characteristics of the train–bridge system affect the vibration frequencies of the car body and bridge
Summary
High-speed railways (HSR) have played an increasingly important role in solving traffic problems in many countries [1, 2], especially for China, which has the largest population in the world. In the seismic analysis of long-span bridges, it is reasonable and necessary to consider the variation of the earthquake excitations under different supports, due to long distance and soil condition change between supports [6, 7]. Xia et al [14] studied the influence of the propagation velocities of earthquake waves on the dynamic responses of the train–bridge system and concluded that no fixed pattern could be observed for the influence of the propagation velocity, the seismic wave passage effect should be considered in evaluating the train running safety. The variation of the earthquake waves at different locations involves the different arrival times and the amplitude and frequency changes due to soil conditions Both should be considered in the seismic analysis of the train–bridge system. The responses of the train–track– bridge coupled system are calculated and compared with the case of a uniform earthquake excitation, a traveling earthquake excitation, and the spatially varying earthquake excitation with different soil types
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