Nonlinear vibrations of CFRP cables excited by periodic motions of supports in cable-stayed bridges

摘要

Owing to its excellent non-corrosiveness and fatigue resistance, a carbon fiber-reinforced polymer (CFRP) stay cable is an ideal alternative to overcome corrosion and fatigue problems associated with the traditional steel cable. However, stay cables are prone to various oscillations under wind, rain, and traffic loading. The vibrations of CFRP stay cables excited by periodic motions of the girder and/or pylons were studied and compared with those of steel cables. A nonlinear dynamic model for in-plane and out-of-plane vibrations of stay cables was proposed. Particularly, the geometrical nonlinearity of the cables was considered in this model. On the basis of this model, numerical solutions were obtained for CFRP cables and steel cables with the same conditions. Furthermore, the effects of important parameters on vibrations were discussed. These parameters included cable tensions, excitation amplitudes, and damping ratios. Results demonstrate that small excitation amplitudes may lead to forced vibrations or parametric vibrations with substantial amplitudes when natural frequencies of the cables are approximately half or one time of excitation frequencies. The maximal vibration responses of CFRP cables are weaker than those of steel cables when their lengths are substantial. As static tensions of the cables decrease, the "beating" frequencies and the maximal amplitudes of the vibrations increase.