Research On Wind-induced Response Of Cross Rope Transmission Tower Line System Under Downburst Wind Load

Downburst is a transient localized strong wind with a certain duration which is induced by a crash of the high altitude air flow onto ground.In recent years,the transmission tower failures caused by downburst have been reported frequently,the downbursts brought great disasters to the national economy and life.This paper relies on the main transmission line of “West-East Electricity Transmission” in China——±800kV Xinjiang Hami to Zhengzhou DC transmission project.Besides,in the western desert area,it is a strong wind prone area such as the downburst.In addition,since the selected transmission line is the double column suspension cable guyed tower line system,there is no research on the wind-induced reponse of the double column suspension cable guyed tower line system under the effect of downburst.Therefore,it is necessary to deeply carry out the wind-induced vibration analysis under the effect of downburst.This paper sums up the analytic model of the wind velocity of downburst and gives the numerical simulation method of wind speed synthesis.Then,the finite element modeling of the double column suspension cable guyed tower line system is performed,the time domain analysis under the imapact of the downburst is performed,and then the relevant parameters of the downburst flow are changed to study the influence of different parameters.The main research works are as follows:(1)Based on the existing theories of downburst,the paper sums up the different analytical models and the simulation methods of fluctuating wind speed.The classical method of vector synthesis is used to simulate the average component of downburst.Not only considering the moving speed of the downburst,but also considering the variation of wind angle with time,then summing up the corresponding rules.Based on the timevarying average wind speed,the harmonic synthesis method is used to simulate the nonstationary pulsation component of the downburst,and finally the wind speed of downburst is obtained.When the wind speed simulation point is large enough that the harmonic synthesis method appears to be not definite and can not be decomposed by Cholesky,POD decomposition can be used instead,but the efficiency is low.(2)Research on the wind-induced dynamic response of the double column suspension cable guyed tower line system under downburst wind load.Firstly,simulate the downburst wind load acting on the double-column suspension cable tower line system,establish the finite element model of the tower line system in ANSYS,and apply the time-domain method to analyze the wind-induced vibration response.This paper mainly studies the pulling force response,the column support counterforce response,the tower displacement and the acceleration response of double column suspension cable guyed tower line system,and studies the response contribution by the pulsating component to the cable tower system.(3)By changing the vertical scale parameters and radial scale parameters related to the downburst,such as the maximum wind speed radius,the storm moving speed,and the vertical distance between the transmission tower and the storm center as listed in this paper.Study on the wind-induced response of the double column suspension cable guyed tower line system under different parameters.The dynamic amplification factor of the pulsating component of the downburst is proposed for the cable tower line system.Based on the theory of probability statistics,the values of the tower top displacement amplification factor and the pull line tension dynamic amplification factor are obtained by calculating a lot of response time-course samples.There is no domestic research on the wind-induced vibration response of such structures.Finally,in the summary work of this paper,the numerical simulation of downburst,the prospect of further research work on the wind-induced vibration response of the double column suspension cable guyed tower line system are proposed.