| In this paper, based on the principle of collapsed steel tower design for Guajing transmission line, the finite element model of multi-tower-line coupled system has been established according to the original data of engineering. Considering the high deference, ice increasing, asymmetry between ices of conductors and wind load, nonlinear buckling analysis of transmission tower-line system under ice load and wind load has been carried out. The ultimate load of tower structure has been studied by using nonlinear buckling analysis and the cause of the tower falling down is analyzed in this paper. It can be concluded that wind load and unbalanced tension caused by overload and asymmetry between ices of conductors are the main reasons why the steel towers fell down, and technical code of design overhead transmission line in heavy icing area needs to be modified.The freezing-rain-ice and wind loads on the transmission tower-line system are simulated with consideration of the model of freezing-rain-ice and the rain classification according to the theory of fluid induced vibration. Based on the principle of transmission tower design in northeastern area, the wind-induced dynamic response of iced transmission tower-line system has been compared with the dynamic response of transmission line wave and quasi-static analytical results. The displacements of tower and line, and the stress distribution of main member are calculated to investigate the behaviors of system. It can be concluded that coupled tower-line system should be taken into account to analyze the wind-induced dynamic response of iced transmission line and the design method in engineering needs to be modified.The non-linear dynamic process of ice-shedding is analyzed first. Then a 3 degree of freedom dynamic model of tower-line system suitable for analyzing ice- shedding is presented. Explicit central difference integral is adopted as the computation method. The time responses of the ice-shedding are acquired. The influencing factors including heighth, span, the angle of coner are studied.According to the characteristics of loading and structure system, and taking into account the wind gradient distribution profile, turbulence flow direction, intensity and power spectral density, the time marching generating method of fluctuating wind has been developed.. Combined with the simulation of wind field, a simulating method of rain loading is presented. A rain-wind-induced dynamic model for transmission tower system is established. A precise finite element model of transmission tower is established. The results of rain-wind induced dynamic response of transmission tower are compared with results of wind-induced response. It is shown that the effect of rain on the transmission towers may not be neglected.The dynamic wind-induced response of iced transmission tower-line system with asymmetrically-iced transmission line has been simulated. In addition, detuning pendulum basing on torsional mechanism was adopted, and its optimization parameters are computed. Optimization parameters of TMD of tower-line system are counted according to the frequency computed from single tower modal analysis. Four kinds of the dynamic wind-induced response of iced transmission tower-line system are compared. Then, wind speed histories of the given field are generated, the dynamic wind-induced response of iced transmission tower-line system with symmetrically-iced transmission line has been compared. It can be concluded that the combination of detuning pendulum and TMD with "dual functions" presented not only provide galloping of the asymmetrically-iced transmission line, but also is of good ability of Wind induced vibration control.
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