Effects of horizontal ground motion incident angle on the seismic risk assessment of a high-speed railway continuous bridge

Abstract

This study investigates the effects of horizontal ground motion incident angle on a high-speed railway continuous bridge (HSRCB). To that end, incremental dynamic analyses (IDA), seismic vulnerability analyses and seismic risk assessments were conducted on a three-span HSRCB subjected to a set of ground motions under five incidence angles θ (0°–90°). The analysis was developed only from the perspective of PGA and the results showed that the longitudinal waves (θ = 0°) only caused seismic responses in the longitudinal direction, while the waves in other directions, especially in the transverse direction, caused a coupling response both in longitudinal and transverse directions for some components, such as the sliding layer and CA mortar layer. The longitudinal seismic damage of the sliding layer and CA mortar layer under the transverse waves should receive more attention in seismic design since the exceeding probabilities and seismic risk probabilities under various incident angles θ are as high as the calculated value for θ = 0°, and with a variation within 5.95%. The maximum variation of the longitudinal response and probability for track parts was within 10.59% under various incident angles, with a significant difference in the transverse response and probabilities in response to different incident angles. In addition, the responses of bridge structure components were more sensitive to the incident angles in comparison with the track parts. Finally, results indicate that the risk probabilities are at a maximum when the ground motions fall within horizontal orientations of 67.5°–90° at the bridge longitudinal axis.