Evaluation of aerodynamic damping in full-scale rain-wind-induced stay cable vibration

Rain-wind-induced vibration of stay cables has been a long-standing problem for cable-stayed bridges. Despite the numerous full-scale and laboratory studies conducted to understand this phenomenon, a consensus on the excitation mechanism that causes the vibration has not been reached. As a result, although many types of formulation have been used to develop models for rain-wind-induced vibration, the capability of these models to effectively predict full-scale vibrations has not been definitively validated. Motivated by the qualitative similarities between the rain-wind-induced vibration and vortex-induced vibration observed in the field, this study proposes to model rain-wind-induced vibration as a Van der Pol oscillator in a manner similar to that used in the modeling of vortex-induced vibration by some previous studies. The model is used as a basis to evaluate the aerodynamic damping resulting from the interaction between the vibration of full-scale stay cables and wind as well as rain, which is the fundamental mechanism that causes large-amplitude vibrations. The dependence of the generalized coefficients representing the linear and nonlinear components of the aerodynamic damping on the characteristics of both the vibration and the wind is interpreted.