Research On Wind Resistance Of Corroded Transmission Towers

Power has become an indispensable part of the People’s Daily life,and the improvement of people’s living standards also makes the demand for power more vigorous.The construction and development of power are related to the people’s livelihood of the country.As an important carrier of electric power transmission,transmission lines play a pivotal role in economic development.China’s vast territory,a large number of transmission lines suffer from different degree of corrosion,which will weaken the carrying capacity of transmission tower rods,which seriously threatens the safe operation of transmission tower.In this paper,a typical 220 k V linear tower in Zhoushan area is taken as the research object,and the self-weight load and wind load on the conductor and ground wire are simplified into the mass point and force loading at the hanging point of the transmission tower,and the finite element model of the 2F14-SZCK transmission tower is established by ANSYS finite element software.With the increase of modal order,the structure gradually changes from global vibration to local vibration.In addition,the stiffness of the cross arm is large,and the local vibration does not occur basically.It is the overall vibration.The local vibration occurs more in the main material or local auxiliary material of the tower body,and the structure of these parts is relatively weak.Based on the stability and strength checking formulas of related codes of transmission tower,the failure formulas of transmission tower members are defined.According to the failure formula,the collapse process of the tower without corrosion is obtained.When the wind speed reaches 42 m/s,the first lateral inclined brace located under the middle cross arm will fail due to exceeding its carrying capacity,and then its symmetric rod will fail,and then the adjacent upper and lower lateral inclined braces will also fail.Finally,the corresponding main rod will exceed its carrying capacity,leading to the collapse of the transmission tower.In this paper,the absolute corrosion of transmission towers is simulated by reducing the thickness of Angle steel,and finite element models of transmission towers at different corrosion sites are established respectively.The natural vibration characteristics,failure wind speed,initial failure rod location,response of transmission tower to wind load,the relationship between DCR frequency and wind speed under different corrosion depths and the distribution of DCR are studied,and the weak positions of transmission towers under different corrosion conditions are analyzed.When the whole part of the transmission tower is corroded,the frequency attenuation of the first-order mode is the fastest,and the structural mode form of the overall torsion gradually changes from the third-order mode to the first-order mode,which greatly increases the risk of transmission wire breakage due to uneven tension,which should be avoided in the design process of the transmission tower structure.The displacement of the top of the transmission tower increases with the increase of wind speed,the corrosion of the rod will make the displacement of the top of the transmission tower increase faster,and the damage wind speed of the transmission tower will decrease with the increase of the overall corrosion depth.In addition,when the corrosion depth is 1.4 mm,the initial failure rod changes from the lateral compression inclined support under the lower cross arm to the lateral compression inclined support of the top cross arm.By comparing the relationship between DCR and wind speed of the two rods,it is found that the lateral compression inclined brace of the top cross arm is more affected by corrosion depth than by wind speed,while the inclined brace of the tower body is more affected by wind speed.In addition,this paper divides the local corrosion into five parts,and studies the changes of the initial failure rods,failure wind speed and DCR distribution of the transmission tower after corrosion at different parts.When local corrosion occurs,the influence on the vibration mode of the transmission tower is relatively small.The natural vibration frequency of the torsion decreases rapidly and the torsion mode changes from the third mode to the second mode,and the destructive wind speed decreases significantly with the increase of corrosion depth.The lower part of the tower is greatly affected by the corrosion depth.The DCR of this part of the tower will increase significantly with the change of the corrosion depth.At the same time,the initial failure position of the transmission tower will be changed.Figure[54] table[20] reference[63]...