On Seismic Response and Hazard of Girder Falling for High-Speed Railway Bridge Considering Constrain Effects of Rail

Abstract

During the 2022 M6.9 Menyuan earthquake, a high-speed railway bridge that is 5 km away from the fault experienced complex movements of girders but no girder falling, which is a contrast with the “Domino” falling of girders of a highway bridge that is 7 km away from the fault during the 2021 M7.4 Maduo earthquake. Inspired by the comparison, this paper investigates the constraint effects of the rail on the movement of the bridge which is usually ignored in seismic response of the bridge. The finite element model of an 8-span simply-supported girder bridge with CRTS I double-block ballastless tracks laying on top is established. Five groups of three-component earthquake records were selected as seismic input to test the constraint effects of the rail under different seismic loads. The results show that, with the constraint of the rail, the amplitude and duration of the acceleration response at the middle span in the longitudinal direction increases, whereas the longitudinal displacement difference between the beam joint and the pier top decreases, reducing the risk of girder falling. In the transverse direction, the rail constraint leads to the reduction of the displacements of the side spans. In the vertical direction, the constraint effect of the rail does not significantly change the peak acceleration and displacement of the bridge.