Abstract:In the light of velocity pulse characteristics of nearfault ground motion and the dominated vibration mode to the dynamic response of floatingsystem cablestayed bridge, a threemass simplified dynamic model was derived and the differential dynamic equation was established. Based on the method of equivalent damping ratio and equivalent linearization of nonlinear viscous dampers, design formulas for determining the damping coefficient of nonlinear viscous dampers of the bridge subjected to nearfault ground motion were deduced. Finally, the accuracy of the proposed design formulas for nonlinear viscous dampers in predicting the damping ratio of the bridge was verified by a real cablestayed bridge.