Experimental Study of Vibration Mitigation of Bridge Stay Cables

Abstract

Vibration mitigation of stay cables in cable-stayed bridges using oil dampers was experimentally investigated with scaled model cables and oil dampers. The increased cable modal damping ratios attributed to oil dampers were measured, and the relationship between the increased modal damping ratio and damper damping coefficient was pursued through a series of free vibration tests. The stay cable-oil damper systems were then driven by harmonic and planar excitation. The linear and nonlinear dynamic behaviors of the systems were observed. Free vibration tests confirmed the theoretical prediction that there is an optimum damper size by which the maximum modal damping ratio can be achieved. Free vibration tests also verified the theoretical finding that cable sag may affect damper performance due to frequency avoidance. Forced vibration tests captured a number of features of nonlinear cable vibration and demonstrated that the installation of a properly selected oil damper to the cable can significantly reduce cable vibration.