Optimisation study of mechanical restraining system in cable-stayed bridges under strong earthquakes

The mechanical restraining system of a cable-stayed bridge, which governs the mechanical connection between the pylons and the main girder, plays a critical role in determining the global force distribution and seismic response of the structure. Conventional designs typically adopt rigid, floating, or semi-floating restraining systems between the pylon and girder of the bridge. Advanced mechanical damping devices and multifunctional bearings have gradually developed toward more durable, reliable and performance-oriented configurations, which provide new solutions for mechanical restraining systems of bridges. In this study, a representative long-span cable-stayed bridge crossing the Panama Canal was taken as a case study. The seismic responses of the bridge were systematically compared among different longitudinal and lateral restraining designs, including fixed, floating, elastic, or damped restraining systems. The results indicate that the damping system provides superior seismic performance, particularly in enhancing structural safety under rare earthquake events. Furthermore, a parametric investigation is conducted to evaluate the influence of key parameters, obtaining an optimised damping characteristic for the restraining system. The findings of this study provide meaningful insights and practical guidance for improving the seismic safety of long-span cable-stayed bridges in high seismicity regions by an optimised mechanical restraining system.