Research On Dynamic Response Of Transmission Tower-line System Considering Joints Stiffness

Overhead transmission lines are an important part of the transmission line system.High-voltage transmission towers mostly adopt the structure of steel trusses,and the tower height is relatively large,which is a high-flex structure.The lattice transmission tower is composed of angle steel members of different sizes connected by bolts and gusset plates.This connection node exhibits mechanical characteristics different from rigid connection and hinged connection.The connection characteristics of the nodes have a certain influence on the mechanical properties of the transmission tower.To solve this problem,an axial nonlinear load-displacement three-fold line model and a bending moment-angle three-fold line model is proposed to realize the stiffness characteristics of the main material lap joint and the K-shaped joint respectively.On this basis,taking the 110 k V transmission line that collapsed during the typhoon in Hainan Province as the research object,the ANSYS finite element analysis software was used to establish a transmission tower and tower-line finite element model considering the stiffness characteristics of the nodes.From the perspectives of modal analysis and the dynamic response under wind and rain loads,analyze the response results considering the stiffness characteristics of the joints on the basis of the transmission tower single tower and tower-line system models that simplify the stiffness effect of the nodes,and explore the influence of node stiffness characteristics on the dynamic characteristics of the transmission tower-line system.The modal analysis results show that the truss beam hybrid model will not change the mode shape of the transmission tower after considering the stiffness characteristics of the nodes,but the natural frequencies corresponding to each order are reduced to varying degrees,among which the second natural frequency the largest decrease was 3.69%.Comparing the dynamic response results of the transmission tower-line system finite element model and the truss-beam hybrid tower-line system model considering the stiffness characteristics of the nodes,it is found that the stiffness characteristics of the nodes slightly increase the axial force of the main materials of the transmission tower.After considering the stiffness characteristics of the nodes the maximum axial force of the failed main material on the windward side and the leeward side increased by 24.68% and 6.05%,respectively.The influence of the node stiffness characteristics on the axial force of the main material node decreases with the increase of the tower height and the influence on the main material on the windward side the degree is greater than that on the leeward side;the stiffness of the node increases the wind-induced displacement response of the transmission tower-line system.The maximum displacement of the cross-arm joints on the windward side and the leeward side is 0.3974 m and 0.3832 m,with an increase of84.26% and 83.13%;the increase of the displacement varies with the tower it can be seen that the influence of node stiffness characteristics on the dynamic response of the transmission tower-line system cannot be ignored.