Theoretical Studies on the Stability of Bridge Piers Under Separable Working Conditions

This study focuses on the influence mechanism of vertical excitation in near‐fault ground motions on the stability of high‐pier bridge structures. To clarify the structural dynamic characteristics under different states, the overall dynamic response of the bridge under the pier‐girder decoupling state is first evaluated. Subsequently, the dynamic displacement response of the pier under the pier‐girder coupling state is analyzed by establishing vibration control equations. When the ground motion excitation period is close to the first‐order vertical natural period of the structure, the difference in the vertical relative displacement between the main girder and the pier increases significantly. This difference directly triggers the vertical separation between the pier and the girder, and the separation will significantly amplify the horizontal displacement response of the pier, thus seriously threatening the stability of the pier. Finally, through calculation and analysis, the regulation effects of bearing stiffness and pier height on the horizontal dynamic response of the pier when considering the vertical separation between the pier and the girder are discussed, providing theoretical support and a design basis for the optimal selection of bearing parameters in the seismic design of high‐pier bridges.