An iterative framework is introduced in this present study to detect seismic isolation precursors of the shortcut calculation method for the isolated benchmark high-speed railway RC bridge. The spatial finite element (FE) analysis model of a benchmark isolated high-speed railway reinforced concrete (RC) bridge system under high-speed railway vehicles is set up based on the equivalent linear method. The vehicle with two bogies is assumed to be represented by a 3 D discrete rigid multi-body system with 23 degrees of freedoms (DOFs). The present study compares the nonlinear seismic response of a high-speed railway bridge with and without isolation bearings. Numerical results demonstrate that the isolation system with the optimal parameters can simultaneously reduce the deck displacement and the internal force of the isolated railway bridge under near-fault (NF) ground motions with various peak accelerations and peak velocity ratios, to ensure the adequate isolation efficiency of isolated structures. Specifically, the study shows that the seismic response of the seismically isolated bridge (IB) and the running safety indexes of the train are primarily dominated by the contents around the fundamental frequency of the train-bridge system subjected to the earthquakes.

This paper focuses on the rapid elastoplastic analyses of light rail vehicle (LRV)- benchmark viaduct system to different seismic scenarios considering the dynamic substructuring method (DSM). Combining the energy-variational principle with the vehicle-bridge interaction (VBI) system, a new framework of train-track system space dynamics is constructed. The present study has established the train-track-bridge coupled system (TTBCS) model, calculated the elastic-plastic seismic responses of the light rail transit bridge (LRTB) subjected to the combined effect of vertical and horizontal earthquakes. Considering three ground motion ensembles, i.e. pulse-like near-fault ground motions (NFGMs), non-pulse-like NFGMs, and far-field ground motions (FFGMs). Results indicate that the large vertical ground motions (VGMs) type NFGMs greatly impact the seismic response of the running safety of the LRV in the low-frequency band compared to the non-pulse-like NFGMs and FFGMs. The results underscore the significance of distinguishing velocity pulses of different types when selecting NFGMs for assessing the nonlinear dynamic response of the VBI system.

Spherical bearings are widely applied in high-speed railway bridges (HSRBs) in China. The experimental and computational analyses were carried out to help understand the damage mechanism of these bearings under earthquake loading. A shaking table test of scaled HSRB specimen (installed with spherical bearings) was performed under the simulated earthquake action, and the intensities were, respectively, 0.15 g, 0.20 g, 0.32 g, and 0.38 g (common intensities in China) of actual earthquakes in accordance with similarity relationships. After investigating and analyzing results of the shaking table test, it is shown that no damage occurred to movable bearings in all experimental earthquake scenarios, while slight damage could be found in fixed bearings at 0.32 g earthquake. Moreover, a finite element (FE) model of the prototype HSRB was established and validated. The damage degree of spherical bearings in stronger earthquakes (i.e., 0.40 g to 1.00 g) was studied through this validated FE model. The numerical results showed that the fixed bearing was completely damaged at 0.80 g earthquake, while only moderate damage occurred to the movable bearing at that intensity.