Response spectra of fitted post‐seismic residual track irregularity for high‐speed railway

Abstract

Chinese high‐speed railway (HSR) network construction has expanded into earthquake‐prone areas. In this context, analyses of post‐seismic residual track irregularity and post‐seismic train speed threshold are vital. With a HSR bridge with track system taken as the study object, time‐domain signal for target post‐seismic residual track irregularity was constructed based on the Gaussian pulse translation theory. The response spectra of fitted post‐seismic residual track irregularity applicable to stochastic structures were established, thus providing irregularity input for ascertaining post‐seismic speed threshold. The results show that residual alignment irregularity has a large amplitude under transverse seismic actions; by contrast, cross‐level, gauge, and vertical irregularities showed small amplitudes. The evolution power spectral density (EPSD) of the stochastic post‐seismic residual track irregularities obeys a definite distribution in any frequency‐space coordinate. A uniquely deterministic target post‐seismic residual track irregularity can be constructed based on the stochastic irregularity set, and its safety guarantee rate can be precisely controlled by varying the significance level. Taking the first‐order transverse natural vibration period as the x‐axis and the amplitude of fitted post‐seismic residual track irregularity as the y‐axis, the response spectra of fitted post‐seismic residual track irregularity can be created. The irregularity response spectra are applicable to stochastic structures.

Design seismic track irregularity for high‐speed railways

“…7,14 The finite element models of the above four components were established by BEAM189 element with elastic custom cross-section, and their material and sectional properties are provided in the literature. 27 Piers are vulnerable to earthquake damage, and the finite element models of piers were established by BEAM189 element with nonlinear generalized cross-section. The momentcurvature relationships required to define the generalized cross-section are illustrated in Figure 4.…”

“…Generally, the seismic track alignment irregularity amplitude is significantly greater than seismic track gauge, cross-level, and vertical irregularity. 27 Therefore, the seismic track alignment irregularity served as a main analysis object in this study.…”

“…The key to determining the threshold of post-earthquake driving speed is specifying a design seismic track irregularity. High-speed railway bearings will be damaged during earthquakes, 14,15 and box girder will deviate from its initial position, 16,17 resulting in seismic track irregularity. 18,19 Design seismic track irregularity refers to the characteristic irregularity that represents many seismic track irregularities.…”

“…It aims to simplify the design seismic track irregularity by replacing random structures with specific structures. 27 However, this study still has deficiencies: (1) the design seismic track irregularity was modeled as a semi-elliptic function, where the slope varies sharply at the beginning and end of the semi-elliptic function. Such a shape distortion will enhance the simulation results of train response.…”

“…proposed an amplitude response spectrum model of design seismic track irregularity to address this issue. It aims to simplify the design seismic track irregularity by replacing random structures with specific structures 27 . However, this study still has deficiencies: (1) the design seismic track irregularity was modeled as a semi‐elliptic function, where the slope varies sharply at the beginning and end of the semi‐elliptic function.…”