Field monitoring and control for vortex-induced vibration of hanger cables in suspension bridge

This study aims to investigate the vortex-induced vibrations (VIVs) characteristics of hanger cables in suspension bridges based on field monitoring and propose effective control strategies to mitigate such vibrations. The vibration monitoring system for VIVs of hanger cables is established. On this basis, the acceleration amplitude, vibration frequency, and the relationship between in-plane and out-of-plane vibration of hanger cables are first investigated. Subsequently, a series of band-pass filters are employed to obtain the acceleration RMS distributions and determine the controlled modes of hanger cables. In addition, the modal damping ratio distributions for the vibration modes are also identified by using the natural excitation technique. Thirdly, the occurrence conditions for VIVs of hanger cables are explored based on the relationships between wind characteristic parameters and the vibration response of hanger cables. Finally, two types of arrayed tuned mass dampers (ATMD) are designed and installed to suppress the VIVs of hanger cables. The results showed that the VIVs of hanger cables are always dominated by multiple modes with large acceleration and high frequency, which are generally recorded when the wind velocity ranges from 2 m/s to 8 m/s. The in-plane vibrations are more frequent and larger than the out-of-plane vibrations. The two types of ATMD can effectively suppress the VIVs of hanger cables. The maximum acceleration RMS reduction of the monitored hanger cables is larger than 85%.