Analysis of seismic damage of a highway bridge during the 2021 Ms 7.4 earthquake in Maduo County, China

On May 22, 2021, a 7.4 magnitude earthquake struck Maduo County (34.59°N, 98.34°E), Qinghai Province, China, with a focal depth of 17 km. The earthquake occurred near the northern boundary of the Bayan Har block. Two highway bridges, including the Yematan bridge, collapsed. Based on the analysis of the seismic damage characteristics of the Yematan bridge, a finite element model of a three-span simply supported girder bridge was established. Nonlinear analyses were performed using the bedrock wave at the bridge site during the earthquake and the seismic safety evaluation wave of the bridge as inputs to analyze the causes of seismic damage to the bridge. The results show that the large beam displacement owing to the velocity pulse and the low-frequency components of the ground motion are the main causes of the damage to the bridge.