Effects of shear keys and track system on the behavior of simply-supported bridges for high-speed trains subjected to transverse earthquake excitations
Abstract:China railway track system II (CRTS-II) slab ballastless track is usually constructed on high-speed railway (HSR) bridges to ensure the rail smoothness and the running safety of high-speed trains, but the use of the longitudinal continuous track system would significantly alter the dynamic characteristics of the bridges and therefore influence the bridge seismic responses. The pounding at shear keys has also been identified as one of the critical factors affecting the seismic behavior of bridges. To investigat… Show more
“…In general, the superstructure of a bridge tends to maintain their elasticity under seismic activity. In the finite element software, we use the elastic frame unit to simulate the box beam, base plate, track plate, and rail [24,25]. The sliding layer, CA mortar layer, fasteners, shear tooth grooves, shear reinforcement, and horizontal blocks play pivotal roles in the transmission of internal forces within essential elements of the track structure [26].…”
As an important part of the boundary conditions on both sides of the high-speed railway track–bridge system, the seismic response of the subgrade structure is different from that of the bridge structure. This difference has become increasingly significant with the widespread adoption of continuous welded rail technology in bridge construction. Therefore, investigating the seismic response of the bridge system, with a specific focus on the longitudinal constraint effects of the subsequent subgrade track structure, is of paramount importance. Utilizing finite element software, two distinct bridge models are developed: one incorporating the subsequent subgrade track structure and another excluding it. Through nonlinear time history analysis under varying seismic intensities, it is demonstrated that the longitudinal constraint of the subsequent subgrade track structure mitigates the longitudinal displacements and internal forces in critical components of the high-speed railway track–bridge system. Concurrently, acknowledging the heightened complexity and cost associated with post-earthquake repairs of the bridge structure compared to subgrade structure, this study uses a risk transfer connecting beam device. This device can redirect seismic damage from bridge structure to subgrade structure, thereby potentially reducing post-seismic repair expenses for the bridge.
“…In general, the superstructure of a bridge tends to maintain their elasticity under seismic activity. In the finite element software, we use the elastic frame unit to simulate the box beam, base plate, track plate, and rail [24,25]. The sliding layer, CA mortar layer, fasteners, shear tooth grooves, shear reinforcement, and horizontal blocks play pivotal roles in the transmission of internal forces within essential elements of the track structure [26].…”
As an important part of the boundary conditions on both sides of the high-speed railway track–bridge system, the seismic response of the subgrade structure is different from that of the bridge structure. This difference has become increasingly significant with the widespread adoption of continuous welded rail technology in bridge construction. Therefore, investigating the seismic response of the bridge system, with a specific focus on the longitudinal constraint effects of the subsequent subgrade track structure, is of paramount importance. Utilizing finite element software, two distinct bridge models are developed: one incorporating the subsequent subgrade track structure and another excluding it. Through nonlinear time history analysis under varying seismic intensities, it is demonstrated that the longitudinal constraint of the subsequent subgrade track structure mitigates the longitudinal displacements and internal forces in critical components of the high-speed railway track–bridge system. Concurrently, acknowledging the heightened complexity and cost associated with post-earthquake repairs of the bridge structure compared to subgrade structure, this study uses a risk transfer connecting beam device. This device can redirect seismic damage from bridge structure to subgrade structure, thereby potentially reducing post-seismic repair expenses for the bridge.
“…The system consisted of a series of train vehicles, a ballastless track model with three layers of elastic point-support and a bridge model (Jiang et al, 2020b). Furthermore, the train subsystem is established by multibody dynamics, and track-bridge subsystems are simulated by the finite element method (FEM) (Meng et al, 2021). Figure 2.Schematic diagram of the TBC model.…”
The increasing prevalence of simply supported bridges in high-speed railway (HSR) lines has raised concerns about the safety of trains crossing these bridges during an earthquake. As these bridges are typically continuous and long, it is essential to consider the effects of traveling seismic waves on the random vibration of the train-bridge coupled (TBC) system. To address this issue, the new point estimate method (NPEM) is used to analyze the dynamic response and parametric sensitivity of a three-dimensional TBC system subjected to non-uniform ground motion with multiple random parameters. The motion equations of the TBC system are derived using bridge seismic theory under multi-support excitations. The analysis incorporates random variables such as the damping ratio, density, Young’s modulus, and seismic magnitude to capture the influence of traveling seismic waves on the random vibration of the TBC system. Simulation results show that the traveling seismic wave effect can cause changes in the first vibration frequencies of the train and bridge, potentially leading to the first few frequencies reordering. Additionally, considering the traveling wave effect will make the TBC system’s response less apparent than without considering the traveling wave effect. The uncertainty of bridge and seismic parameters can seriously affect the train’s running safety. The sensitivity of the bridge density and seismic magnitude is particularly prominent for bridge responses when the traveling seismic waves effect is strong. This methodology can be used for random and sensitivity analysis of a train running over a long bridge under non-uniform earthquake conditions. Overall, the NPEM can provide valuable insights into the dynamic behavior and safety of TBC systems, enabling more effective design and maintenance of HSR bridges.
“…Xu et al [ 21 ] proposed a new type of shear key for the retrofit of existing highway bridges and experimentally studied its seismic behavior under repeated monotonic loading. Meng et al [ 22 ] studied the effects of shear keys and CRTS-II track systems on the seismic behavior of single-supported bridges of the high-speed rail under transverse seismic excitation. In general, the seismic pounding response of reinforced concrete bridges has been studied in depth.…”
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