Nonlinear Dynamic Analysis of Tall Bridge Piers Under Multidimensional Pulse Earthquakes Considering Varying Damping Ratios

The dynamic response of tall bridge piers with varying damping ratios under three-dimensional pulse ground motion remains insufficiently understood. To control the pulse characteristic parameters accurately and eliminate interference from actual seismic records, this study uses the earthquake wave synthesis software to generate three pulse seismic waves and non-pulse seismic waves with varying seismic characteristic periods. The dynamic response analysis of tall bridge piers under one-dimensional, two-dimensional, and three-dimensional seismic input conditions is carried out. The influence mechanism of pulse effect, damping ratio and ground motion dimension on structural response is mainly discussed. The results show that the peak displacement and peak shear stress response of tall bridge pier structures under pulse ground motion are 0.0614 m and 0.1727 MPa larger than those under non-pulse ground motion, respectively. The responses of the displacement and shear stress of the tall bridge pier subjected to pulse ground motion exceed those under non-pulse ground motion. When the action time exceeds 18 s, the influence on the displacement and shear stress time history curve of the tall bridge pier is ranked as follows: pulse ground motion > damping ratio > non-pulse ground motion. Under multidimensional non-pulse ground motion, the maximum errors in peak displacement at the Z section and peak shear stress at the YZ section of a tall bridge pier are 0.05% and 5.27%, respectively. These errors increase to 0.67% and 1.68% under multidimensional pulse ground motion, respectively. Compared with one-dimensional seismic conditions, two-dimensional and three-dimensional ground motions result in smaller displacement and shear stress errors at the Z section, but larger errors at the X section, particularly for peak displacement and shear stress at the YZ section. This highlights the greater complexity of multidimensional seismic forces and their varying impacts on different sections of tall bridge piers.