Analysis Of Wind Vibration Response And Dynamic Stability Of Transmission Tower-line System

The transmission tower line system has the characteristics of light weight,high flexibility,long span and small damping,and is sensitive to the excitation of wind load.The collapses of transmission lines due to wind occur from time to time.The existing transmission line design specifications separate the design of the tower and the line,only the wind load on the transmission line is equivalent to concentrated load applied to the transmission tower for calculation and design.The negative effects of dynamic tension of the transmission line caused by the tower-line coupled vibration on the structure of the transmission tower is not considered.Therefore,it is of great theoretical significance to study the dynamic characteristics,wind-vibration response and dynamic stability of transmission tower-line system,which can provide reference for transmission line design.The main work of this paper is divided into the following parts:(1)The beam-girder hybrid model with high simulation accuracy is used for finite element modeling of transmission tower.The gravity self-balancing shape finding method is used to find the shape of the transmission line,and the sag value and stress value of some nodes after the shape finding are compared with the theoretical value,which verifies the effectiveness and accuracy of the shape finding of the transmission line.Then,the three-tower two-line finite element model that is more in line with actual engineering project is used to model the tower-line system,and the dynamic characteristics of the transmission line are analyzed using the Block Lanczos method in ANSYS.(2)Based on the Harmonic superposition method,MATLAB software is used to simulate the wind speed time history samples at each load application point of the transmission tower-line system,and the Fast Fourier Transform(FFT)technology is used to improve the computational efficiency of the algorithm.By comparing the simulated wind speed power spectrum with the target spectrum,it is found that the agreement between them is high and the trend is consistent,which indicates that the simulated wind speed time history is accurate and reliable.(3)The time history of wind vibration response of transmission tower-line system is calculated by using the Newmark-? method on finite element analysis software of ANSYS.The effects of different wind direction angle conditions on the tower line wind vibration response are analyzed,and compared with the results of single tower static analysis of the standard calculation.The comparative analysis shows that: under the effect of design wind speed,the standard algorithm under the condition of 0 degree wind angle is conservative,and the influence of the coupling effect of tower and lines on the dynamic amplification effect of transmission tower should be properly considered in the design under the condition of 45,60 and 90 degree wind angle.At the same time,the analysis results of the wind vibration response of the tower line system under the wind angle of 90 degree are compared with that of single tower,and the dynamic amplification effect of the coupling effect on the transmission tower cannot be ignored.The influence of different wind speed on the wind vibration response of the tower line system under 90 degree condition is also studied.The research shows that the response of each part of the transmission line increases with the increase of wind speed,and the coupling effect of the tower line system becomes more and more obvious.The coupling effect of tower line system should be considered under strong wind.(4)Based on finite element analysis software of ANSYS,Incremental Dynamic Analysis(IDA)and B-R criterion combined with displacement equality criterion are used to analyze the dynamic stability of the column line system at 90 degree wind angle,and the dynamic stability analysis results are compared with the dynamic stability analysis results of single tower and the nonlinear buckling analysis results.The results show that the tower line system has dynamic instability under the pulsating wind speed of 37m/s,which is lower than 43m/s wind speed in dynamic instability analysis of single tower and the average wind speed of 46.332m/s in the nonlinear buckling analysis of single tower.Therefore,the influence of transmission line on the dynamic stability of transmission tower should not be neglected and the influence of transmission lines should be considered in the design of transmission towers.