Magnitude-based damage analysis of high-speed railway track bridge system across canyon

Abstract

Due to the significant impact of topographic effects on seismic intensity, the spatial attenuation relationship of seismic waves during actual earthquakes is usually complex. Traditional seismic fragility analysis methods rely on input from ground motions (GMs), making conducting rapid damage assessments difficult. Accurately simulating the process of seismic wave propagation from the hypocenter to the bridge site is crucial for the rapid evaluation of high-speed railway track-bridge system (HSRTBS) during seismic events. This study overcomes the limitations of classical seismic fragility analysis by proposing a HSRTBS seismic fragility analysis method considering moment magnitude (M_w). Taking a canyon in China as the site, a physics-based seismic simulation method is used to model the propagation process of seismic waves from the hypocenter through the geology and topography under various M_w values. A probabilistic seismic demand model (PSDM) considering M_w is developed via the cloud analysis (CA), and the relationship between M_w and the damage probability of HSRTBS is quantitatively analyzed. The results show that canyon topography significantly affects the seismic response and damage distribution of HSRTBS, with notable differences across different slope types. The face slope's peak ground acceleration (PGA) amplification factor can reach 1.78. In contrast, the back slope exhibits a certain degree of attenuation due to interference effects, which follows a similar pattern to the seismic records from the Chi-Chi earthquake in the Feitsui canyon. The proposed seismic fragility analysis method considering M_w for enables rapid damage assessment of HSRTBS under specific seismic scenarios. This approach overcomes the limitations of traditional seismic fragility analysis, which cannot account for complex topography.