Field survey and analysis on near-fault severely damaged high-speed railway bridge in 2022 M6.9 Menyuan earthquake

The 2022 M6.9 Menyuan earthquake caused severe damage to a high-speed railway bridge, which was designed for high-speed trains running at speeds of above 250 km/h and is located right next to the fault. Bridges of this type have been widely used for rapidly constructing the high-speed railway network, but few bridges have been tested by near-fault devastating earthquakes. The potential severe impact of the earthquake on the high-speed railway is not only the safety of the infrastructure, trains and passengers, but also economic loss due to interrupted railway use. Therefore, a field survey was carried out immediately after the earthquake to collect time-sensitive data. The damage to the bridge was carefully investigated, and quantitative analyses were conducted to better understand the mechanism of the bridge failure. It was found that seismic action perpendicular to the bridge's longitudinal direction caused severe damage to the girders and rails, while none of the piers showed obvious deformation or cracking. The maximum values of transverse displacement, out-of-plane rotation and twisting angle of girders reached 212.6 cm, 3.1 degrees and 19.9 degrees, respectively, causing severe damage to the bearing supports and anti-seismic retaining blocks. These observations provide a basis for improving the seismic design of high-speed railway bridges located in near-fault areas.