Eddy Current-Friction Hybrid Damper: A New Solution for Longitudinal Motion Control in Suspension Bridges

Floating-type suspension bridges suffer critical longitudinal motion issues during operation, including bearing wear, expansion joint failure, fluid damper leakage, and short hanger fatigue caused by reciprocating stiffening girder movements. This study introduces an eddy current-friction hybrid damper to address these challenges. Case studies on highway and railway bridges show that the damper effectively reduces longitudinal motion under operational and seismic loads. Under operational loads, it reduced peak displacement at girder ends by over 70% and cumulative displacement by 50%. During seismic events, peak displacement reduction at girder ends exceeded 50%, with minimal increase in moment and shear force at the tower base. The damper, with carbon/carbon composite friction plates, has an annual friction degradation rate of less than 0.01%, ensuring long-term durability and superior control performance.