Theoretical Study on Dynamic Stability of High Bridge Piers Under Near-Fault Earthquake

Abstract Select a double span box girder bridge as the analysis model, the vibration control differential equation of ultra-high pier is established, solved by the Runge-Kutta method with variable step length, combined with B-R motion criterion, the dynamic response of ultra-high pier induced by vertical seismic excitation is calculated, and the instability mechanism is studied. Theoretical analysis shows that for high piers, ignoring the bidirectional coupling effect will underestimate the dynamic response of piers. The vertical seismic excitation results in the increase of the axial pressure of bridge pier, which will increase the horizontal deformation of pier. The separation of the main beam and bridge pier will change the extreme deformation value of the bridge pier and increase the risk of pier instability. It has important guiding significance for the theoretical analysis and engineering practice of dynamic instability of ultra-high pier.