Effects of near-fault pulse-type ground motion on train–track–bridge coupled system with nonlinear supports

Researches have revealed that the excitations of near-fault pulse-type (NFPT) earthquakes lead to significant challenge of high-speed railway. This paper mainly focuses on the dynamic responses of train–track–bridge coupled system (TTBCS) under NFPT ground motions. An innovative effective TTBCS model (TTBCM) considering nonlinearities of supports is proposed herein, and with that model, numerical simulation and data analysis are conducted to reveal the potential effect on TTBCS arisen by NFPT ground motion from both qualitative and quantitative perspectives. Conclusions can be summarized below: The comparison between linear model and nonlinear model reveals the necessity of nonlinearity when conducting TTBCS numerical simulation under NFPT ground motions. Moreover, the analysis of pulse parameters of NFPT ground motions reveals that the relationship between dynamic responses of train group and amplitude of velocity pulse is approximately to the linear positive correlation relationship, while the dynamic responses of train group and period of velocity pulse exhibits negative correlation as inverse proportional function. Based on parameters analysis, a multiple-parameter regression between spectral intensity and pulse parameters is conducted, with the combination of running safety assessment (RSA) criteria including Nadal, wheel unloading, and wheel lift, suggestion from RSA perspective under NFPT ground motions are proposed as well.