Influence of damping on seismic-induced track geometric irregularity spectrum in high-speed railway track-bridge system

Abstract

Track irregularities are an important factor affecting the safety, smoothness, comfort, and lifespan of high-speed railway track structures. Damping greatly affects the seismic response, and the influence of damping on seismic-induced track geometric irregularities is of significant interest. In this study, the simple-supported beam bridge of the CRTS-II ballastless track high-speed railway was adopted as the research object. A power spectral density curve spectrum of seismic-induced track geometric irregularity based on guarantee rate was established, and the influence of structural damping ratio on the power spectral density curve under different earthquake intensities was analysed. A simplified calculation method for power spectral density curve of seismic-induced track geometric irregularity was proposed. The main findings of this work are as follows: (1) Seismic-induced track irregularities of high-speed railway bridges are dominated by alignment irregularity, and a segmented polynomial function can be fitted to the power spectral density curve of the seismic-induced track irregularity based on guarantee rate; (2) Seismic-induced track irregularities of high-speed railway bridges worsen as structural damping decreases and peak ground acceleration increases; (3) More spikes are observed in the high-frequency waveband of the power spectral density curve, and seismic-induced track irregularity results in more high frequency periodic components.