Numerical study on the effectiveness of two dampers on high-order vortex-induced vibration and low-order rain-wind-induced vibration of stay cables

In recent years, high-order vortex-induced vibrations (VIVs) of ultra-long stay cables have been frequently observed on real bridges. However, additional dampers or aerodynamic measures were often designed to suppress wind-rain induced vibrations (RWIVs) of stay cables, which is mainly for the vibrations of low-order modes. This brings new challenges to the vibration reduction of stay cables. In this study, the theoretical models are used to investigate VIV and RWIV characteristics of ultra-long stay cables and verify the validity of installing two viscous dampers at the lower end of stay cables to suppress low-order RWIV and high-order VIV simultaneously. First, an empirical model, the wake oscillator model, is introduced to study VIV characteristics of stay cables subjected to different wind profiles, damping ratio and wind velocity, and the linear wake-structure coupling resonance is also introduced to investigate VIV mechanism of the stay cable. Second, the characteristics of RWIV of ultra-long stay cables based on the existing RWIV model is investigated. Finally, the optimizing parameters of the cable-dampers system is conducted for simultaneous control of RWIV and VIV, and the multimode damping is investigated. Finally, the study compares and analyzes the control effect of the multimode vibration with different measures.