Improving cable-stayed bridge longitudinal aseismic capability via fluid viscous damper parametric optimization and experimental investigation

Abstract

The seismic vulnerability of Cable-stayed Bridges (CSBs) in high-earthquake intensity areas can be of significant concern to structural safety and resilience. A promising design practice for CSBs depends on decoupling the girder from the girder-pylon connection and involving energy dissipation devices such as fluid viscous damper (FVD) to mitigate the seismic responses. However, the parametric damper optimization algorithm and experimental validation on the FVD of a longitudinal aseismic system for CSB is still limited. In this study, three longitudinal aseismic systems (a semi-floating system with an elastic or damper connection, and a pylon girder consolidation system with a rigid connection) were investigated and compared based on the actual bridge Xigu Yellow River CSB erected in Lanzhou, China. The non-linear time history methodology was implemented to analyze the pylon and girder’s displacement and internal force responses, and the fluid viscous damper (FVD) aseismic system was the optimal choice considering the oval seismic performances. The optimal damping parameters were obtained by conducting parametrical analysis based on qualitative analysis and non-linear multi-function optimization in the pylon-girder and auxiliary pier-girder connections. A full-scale FVD model was designed and manufactured to conduct low velocity, constitutive law, and damping efficiency tests. The experimental results indicate that FVD achieved good energy dissipation capability and stability. FVD damping parameters were deduced according to the constitutive law test. The optimal analytical FVD damping parameter agreed well with the experimental results. Furthermore, the optimization was implemented in the final bridge design, referencing longitudinal aseismic systems for CSBs.