Dynamic Tension Model for Wind-induced Vibration of Long Spanned Transmission Line

The wind-induced dynamic tension in transmission lines is one of the key issues in wind resistant design of power transmission towers. As a type of flexible structure, the wind induced vibration of transmission lines exhibits typical nonlinear characteristic with large displacements and small strains. Based on vibration equation of a continuous suspension cable system, dynamic tension of the transmission line caused by windward loading was decomposed into two parts, nonlinear static force generated by mean wind and linear dynamic force generated by turbulence wind in its equilibrium plane. Studies showed the first out-of-plane mode and the first symmetric in-plane mode are two dominant modes leading to the dynamic tension force of the transmission line, so the time-domain expression and frequency-domain power spectrum of windward dynamic tension was obtained according to the 1st-order generalized displacement. Thus a 2-freedom-degree mechanic model for dynamic tension was constructed. Results showed the efficiency of the given method, in comparison with nonlinear finite element analysis in the application to a real transmission line.