Parametric analysis of sedimentary V-shaped canyon for seismic response of canyon-crossing bridges

Previous earthquakes reveal that the sedimentary V-shaped canyon (SVC) may result in severe damage of canyon-crossing bridges (CCBs). The seismic response of CCB is affected by various parameters, including sedimentary soil characteristics and fault rupture mechanisms. However, these influential parameters of SVC on the seismic response of CCB have not been sufficiently studied in the existing literature. Thus, this study aims to identify the most influential factor on the seismic response of bridges across SVC using parametric analysis. For this purpose, the spectral element method (SEM) is adopted to simulate the wavefield of SVC considering the fault dynamic rupture. The characteristics of ground motions in the Forward region (FR) and the Middle region (MR) are investigated. The sensitivity of ground motions recorded in SVC to four main influential factors (i.e. shear wave velocity of sedimentary soil V_s, the ratio of sedimentary soil depth to canyon depth d/D, layer sequence O, and fault-to-canyon distance R_rup) is numerically evaluated. Furthermore, the parametric analysis is performed to estimate the impact of these influential parameters on the seismic response of a CCB. The results reveal that the amplitudes of pulse-type ground motions in the illuminated side of SVC increase with the decrease of V_s. As the V_s decreases from 2300 m/s to 400 m/s, the residual deformations of four bearings increase by 293 %, 93 %, 451 %, and 292 %, respectively. When the d/D is 0.3, the velocity pulse ground motions in SVC have the largest PGVs. The base shear of the piers in the case of d/D = 0.3 increases by more than 77.3 % compared to that without considering the sedimentary soil (d/D = 0). The inverted sequence may result in larger seismic responses of bearings and piers compared to normal sequence. R_rup has the most significant effect on the seismic response of CCBs. The higher-order effect and additional plastic hinges are more noticeable when R_rup is less than or equal to 7.5 km.