Study on Energy-Dissipation Constraint Systems for Sea-Crossing Extra-Long-Span Multi-Pylon Cable-Stayed Bridges

Cable-stayed bridges are widely used due to their exceptional spanning capacity. This paper takes the extra-long-span multi-pylon cable-stayed bridge of the Huangmaohai Crossing Project as the engineering background, systematically investigating the rational configuration of its energy-dissipation constraint system. Firstly, the longitudinal constraint scheme employing elastic restraints at the central pylon and viscous dampers at the side pylons is analyzed. Studies demonstrate that this system can significantly reduce the bending moment at the base of the central pylon by up to 42% compared to the fixed connection scheme at the central pylon, while effectively controlling girder end displacements. Secondly, the responses of four transverse restraint systems under seismic action are compared, leading to the selection of a transverse seismic isolation system utilizing friction-pendulum bearings and energy-dissipating anti-wind bearings. The selected system provides a more balanced compromise between displacement control and internal-force reduction by redistributing transverse seismic demand among the girder, pylons, and piers. The research outcomes provide a system-level design reference for the restraint and energy-dissipation configuration of similar extra-long-span multi-pylon cable-stayed bridges.