Seismic performance of skewed bridges with rocking columns

Abstract

Rocking structures that possess damage control and self-centering capabilities represent an effective approach to achieving rapid post-earthquake functionality recovery in bridges. Currently, most research on rocking bridges focuses on regular bridges, whereas the seismic performance of rocking columns in skewed bridges, which are prevalent in engineering practice, remains largely unexplored. In this study, the seismic response and influence of structural parameters of skewed rocking bridges under three-dimensional earthquakes are analyzed, considering nonlinear boundary conditions such as abutment-soil interaction, pounding effects, and pile-soil interaction. The results demonstrate that the skew angles have more impact on the translational displacement, deck rotations, and unseating risk in skewed rocking bridges compared to those observed in cast-in-place (CIP) bridges. Although a considerable residual rotation angle is present in skewed rocking bridges, it is much smaller than that observed in CIP bridges, and the residual displacement of columns is minimal, facilitating the quickest possible restoration after an event. As the skew angle or the constraint gaps increase, the responses of prestressed rocking bridges with dampers gradually exceed those of CIP bridges, especially the deck rotation and unseating risk. Compared to CIP bridges, skewed rocking bridges are also more sensitive to changes in the incidence angles of ground motions. Enhancing the bearing capacity of shear keys is a possible mean to diminish the sensitivity of rocking skewed bridges to the direction of seismic inputs.