Dynamic analysis of a cable model subjected to both vortex-induced excitation and axial support motion

Large amplitude vibration of transmission line seriously affects the structural safety. Due to the low bending stiffness of superhigh transmission tower, vortex-induced excitation combining with support motion induced by the tower will cause significant complex dynamic behaviors of the transmission line. To reveal dynamic behaviors, this paper newly proposes a suspended cable model of the transmission line subjected to the boundary motion and vortex-induced vibration. Dynamic mechanism and vibration energy transfer are focused in the condition of primary and subharmonic resonances. Innovative behaviors of the transmission line under two excitations are revealed. Firstly, vortex-induced excitation is very weak and support motion usually plays a dominate role in the dynamic responses. Large amplitude vibration of transmission line observed in practice should be caused more by tower tip motion and the vortex-induced vibration is the incentive. Secondly, different weak support motion can cause different effect on dynamic responses of transmission line under vortex-induced vibration reflecting by different lock-in phenomenon, which leads us the application of active control measure in engineering.