Influence of Dampers on Seismic Response of Cable-Supported Bridge Towers

Abstract

Nonlinear time history analyses were performed to investigate the seismic response of the new San Francisco–Oakland Bay Bridge East Span self-anchored suspension (SAS) bridge and cable-stayed (CS) bridge alternative with the signature towers protected by friction dampers and viscous dampers in lieu of the as-designed steel shear links. Response of the damper and shear link equipped towers were compared to determine if equipping bridge signature towers with passive dampers, that would not experience residual deformations, is a viable option for cable supported bridges, particularly in retrofit applications. Viscous dampers were the most beneficial to the SAS and CS tower response in the transverse direction of the bridges. Dampers placed in toggle-braced configurations further improved the tower response for the SAS bridge transverse direction by magnifying the damper displacement demands. With the addition of stiffness to the signature tower being more critical in the longitudinal direction than in the transverse direction, the diagonal friction dampers were the most beneficial in the longitudinal direction of the SAS bridge tower.