Study On Strength Of Towers In Multi-span Tower-line Systems

In recent years,mechabical accident like transmission tower falling in ice area happen from time to tome.The reason of transmission damage has caused extensive concen and become a hot reaserch topic.They are the main cause of transmission line tower damage including ice,wind,conductor ruture and settlement which is considered in the design of transmission line.Therefore,it is very important for tower design and improvement that analyze stress and deformation of tower line system and strength.This paper takes No. 61- No. 66 actual line section of Sichuan 500 k V Yue-Pu general double circuit as the research object, by use of finite element numerical method, firstly, we established six tower-seven span tower-line coupling system finite element beam-truss and spatial beams model,compare the difference of natural requency and modal between two model.In addition,calculate the dynamic characteristics of tower line system,the low-order modal are characterized by wire and groud deformation.Analyze the tension and straight tower of stress distribution and strenght in 7 kinds of ice and 11 kinds of combination of ice and the wind,comparing stress and deformation the results of beam-truss model and spatial beam model.Conductor or ground wire fracture in the transmission line tower system, will produce large unbalanced force on the tower.Computing thirteen kinds of uniform and non-uniform ice cases,analysising the dynamic response of tower line system and getting the result of stress distribution of the tyical tension tower.At the same time using the transmission line design procedures in IEC about the static method,analysis the tension tower,comparing the dynamic and static calculation results,research the tower response difference between traditional method and conductor break in tower line system,and point out the shortcomings and put forward suggestions.Finally, using the finite element method, simulating the foundation settlement of tower brings the effect of line system security.Getting the result of tower line system stress and deformation by simulating the tension tower single leg and legs settlement. When tower single leg settlement exceed 100 mm, the stress of the tower will be greatly increased, the maximum stress will be more than the ultimate strength.In addition, in the same situation single leg settlement and the double legs,stress of the tower is smaller than single leg settlement.Numerically simulated the tower of stress and deformation under different cases including ice,wind,congductor rupture and foundation, analysis strength of transmission tower, and evaluate the current design load. The results of numerical simulation is very valuable reference for the design and improvement of tower line system.