Simulation On Nonlinear Collapse Of Transmission Tower-line System Under The Action Of Typhoon Loading

In recent years,China’s economy continues to grow,the demand of the electricity is growing gradually,the construction of high-grade power grid system has become the strategic goal of the country’s growing development,and the transmission tower system which needs cause enough attention to the engineering practice plays an important role in our daily life;As a kind of wind load-sensitive structure,transmission towers are often damaged by typhoons.Once the continuous collapse happens,it will cause serious blows to the national economy.Therefore,this paper simulates the time-history of non-stationary typhoon fluctuating wind speed and wind load through the measured typhoon wind speed samples in a numerical way,and the finite element numerical model of the tower line system with three towers and four gears is established.The improved implicit nonlinear analysis method in the ANSYS finite element software is adopted.The simulation of typhoon wind load time history is applied to ANSYS finite element model with command flow written by APDL,and the continuous collapse failure process of the UHV transmission tower system model is analyzed.The main research content of this paper is compiled into the following parts:1.According to the typhoon wind speed sample collected in the field,the non-stationary characteristics of typhoon are analyzed,and the feasible method of time-varying mean wind speed of typhoon is explored.The time-varying trend term in the original wind speed sample is extracted by using the discrete wavelet transform（DWT）,and the downwind time-varying trend term is taken as the time-varying mean wind of the non-stationary typhoon.2.Using the harmonic superposition method to simulate non-stationary random process under the action of powerful typhoon time history of wind speed and wind load time history,the modulation function of non-stationary typhoons is developed,and the spectral density of non-stationary process of strong typhoons is calculated by the modulation function.The evolution of spectrum is defined as the time and frequency of joint function,therefore,evolution spectrum is also defined as time spectrum,which can reflect the distribution state of signal energy in both time domain and frequency domain.3.According to the existing drawing data,the tower line system of finite element numerical model is established through ANSYS software GUI interface and APDL programming language,,including the model of transmission tower,conductor and insulator.Static analysis and modal analysis are carried out on the tower-wire coupling system according to the results of modal analysis.The natural vibration period and modal patterns of each order of the structure system are obtained,which provide theoretical data for the subsequent analysis of transmission tower collapse.4.According to the multi span transmission line tower system which is established above,the wind load time history of transmission tower and guide line under typhoon action is applied in ANSYS through APDL programming language,so as to realize the failure analysis of multi-span transmission tower line system under non-stationary typhoon action.Finally,the transient dynamic analysis is carried out on the transmission tower line system.To realize the component failure simulation of the structural system under the action of typhoon,and then to achieve the collapse simulation of transmission tower system.The failure criteria of the component is given to provide theoretical and technical support for the actual collapse of transmission tower structure.