System-based probabilistic optimization of fluid viscous dampers equipped in cable-stayed bridges

This study presents a methodology to evaluate the optimal parameters of fluid viscous damper for cable-stayed bridges using the system-level fragility assessment approach. Instead of investigating the impact of different isolation devices on the component's vulnerability separately, this study focuses on evaluating the optimal parameters of fluid viscous damper to achieve the best overall performance of cable-stayed bridge as a system. Numerical model of a cable-stayed bridge with the most common configuration in China is established using OpenSEES that can account for their nonlinear response and uncertainty treatment. A joint probabilistic seismic demand model and Monte Carlo simulation are employed to obtain the system fragility of cable-stayed bridges by accounting for the contribution of multi-components to the global damage state. The system-level fragility curves and component fragility curves are compared before and after the application of fluid viscous damper with different parameters. The results indicate that a given parameter of the fluid viscous damper may have a negative impact on some components, yet lead to a better performance of the bridge as a system. Thus, in order to obtain comprehensive knowledge of bridge performance and derive the accurate optimal parameters of fluid viscous damper, it is necessary to consider the fragility based on bridge system.