Research On Wind-induced Effects Of Existing Transmission Towers Considering Component Aging

Thanks to the sharp increase in demand in the industrial and civil fields,my country’s power industry has developed rapidly,and a large number of power transmission facilities have sprung up.With the passage of time,the transmission tower is subjected to a combination of factors in the outdoor environment,and its tower body components will gradually age.In order to prolong the service life of the rod,there are many measures to prevent corrosion,but the most commonly used is to apply hot-dip galvanized coating.Firstly,the paper analyzes the coating and determines the minimum protection life of the coating in C4,C5 and CX environments.Then,through the protection life,the relationship between the corrosion depth of transmission tower rods and time under the three environments is analyzed.The node characteristics of steel structure are applied to the transmission tower structure,the existing finite element modeling method of transmission tower considering node semi-rigid is optimized,and the finite element model of transmission tower is established.The results show that the rotational stiffness of the node has little effect on the first six modes of the transmission tower;The wind-induced response analysis is carried out by using the time-domain method.It is concluded that the rotational stiffness of the node has little influence on the node displacement,the acceleration of the node and the axial force of the rod of the transmission tower,but has a great influence on the bending moment.With the gradual decrease of the rotational stiffness,the bending moment of the rod also decreases.The finite element model of the whole tower corrosion of the transmission tower under different service times in the C4,C5 and CX environments is established;In the C5 environment,the first six vibration modes of the tower will not change within 50 years of service;in the CX environment,the first six vibration modes of the transmission tower will not change within 13 years of service.The shape begins to change gradually.The windinduced response analysis of transmission towers in different environments shows that with the increase of service life,the displacement and acceleration of the tower body will show different degrees of growth,but the change of displacement is more obvious;the axial force of the rod increases the corrosion rate sensitivity is small,and the stress will gradually increase with the increase of the corrosion rate of the member;the change of the bending moment of the member is related to the rotational stiffness of the node and is less related to the corrosion rate of the member.The damage study of the transmission tower found that from the perspectives of stiffness,rod strength,and instability,under the two environments of C4 and C5,the transmission tower will not be damaged within 50 years of service,and it can still maintain operation.In the CX environment,at 28 years,the tower body displacement reached the failure standard;at 29 years,the rod strength reached the failure standard;at 12 years,the rod was unstable.The transmission tower is divided into main material and inclined material to consider the effect of local corrosion under different corrosion rates.The mode shape results show that the change of the main material mainly controls the first-order bending moments in the X-axis and Y-axis directions,while the change of the inclined material affects the first-order bending moment.The first-order torsion in the Z-axis direction has a greater impact;through research,it is found that the change of the main material is the main factor affecting the wind-induced effect of the transmission tower.The main materials of the tower head,tower waist and tower legs are selected for corrosion analysis to consider the wind-induced response changes at different positions of the main materials.With the increase of the corrosion rate,the acceleration of the nodes at both ends of the main material of the tower head and the tower leg also increases,and the acceleration of the nodes at the two ends of the main material of the tower waist decreases accordingly;the stress of the corroded rod increases with the corrosion rate.When the corrosion rate of the main material of the tower head is 49%,the main material in the tension zone reaches the yield strength,and when it is57%,the main material in the compression zone reaches the yield strength;When the corrosion rate of the main material of the tower waist is 31%,the main material in the tension area reaches the yield strength,and when it is 37%,the main material in the compression area reaches the yield strength;the corrosion rate of the main material in the tower leg is35%.Yield strength,at 47%,the main material in the compression zone reaches the yield strength.Figue [47] table [39] reference [76]...