Analysis of seismic damage mechanism of simply supported girder bridges at near‐fault liquefaction sites

Abstract

Abstract This work uses the Yematan Bridge as an example to explore the seismic damage mechanism of simply supported girder bridges at near‐fault liquefaction site. It analyzes the bridge from the local portion to the complete bridge, considering the effects of the near‐fault and liquefied soil layers. First, a three‐dimensional model of the pile‐soil seismic action of Pier No.17 was created using simulated near‐field ground motion, and analysis was performed to simulate the action of the liquefied soil layers on the pile foundation, getting pile‐soil dynamic p‐y curves. After that, the accuracy of the pile spring parameters was verification by doing an equivalent static analysis. Finally, to identify the seismic damage mechanism of high‐damping rubber (HDR) bearings and the dynamic unseating process of the Yematan Bridge, a finite element model of the complete bridge was developed. During this procedure, the near‐field ground motion amplitude and soil spring parameters were iterated and optimized continually, such that the simulated earthquake damage was identical to the real one. The findings suggest that the bridge was destroyed by significant structural vibration. The near‐fault impulse effect and lack of equivalent limiting measures induced the entire collapsing girders to move consistently and destroyed the HDR bearings. Liquefied soil can cause some damage to pile foundations, and lateral spreading can cause the piers of the same span to perform differently.

Keywords

• equivalent static analysis
• liquefied soil
• near‐fault ground motion
• nonlinear analysis
• seismic damage mechanism
• simply supported girder bridges