Accurate Modeling Of Structural Joint And Its Application In Lattice Transmission Tower Analysis

Transmission towers are vital components of overhead transmission lines, which play an important role in the operation of electrical power systems. In order to store, transport and fabricate conveniently, lattice transmission towers are commonly constructed by hot-rolled equilateral angle steel struts through bolted joint. Because the way joins are structured will effect the bearing capacity of lattice transmission tower, so it is necessary to study how to including the joint effects in the lattice tower analysis. Accurate prediction of failure sequence and ultimate load of lattice transmission tower in various working conditions is very important for the reliability and safety of transmission lines.In this paper an accurate modeling method for bolted joint in lattice transmission tower is presented, several numerical models of a new 220kV anti-icing tower with considering joint effects are created to study the non-linear static behavior, bearing capacity subject to ground deformation and dynamic response of lattice transmission tower, and the infulence of joint effects on the mechanical behavior of transimission towers is obtained. The contents of this paper as follow:1) The slip process of bearing type bolted joint in lattice transmission tower is analyzed, a new joint slippage model is presented, and the parameters are determined after discussing their effects on the slippage model.2) Joint slippage and joint stiffness are accurate modelled by using six nonlinear springs, four numerical models of a new 220kV anti-icing tower are built according to whether including joint slippage, joint eccentricity and various joint stiffness.3)The effects of joint slipage, joint eccentricity and joint stiffness on the internal force and deformation of lattice tower are studied, experimental results from full-scale prototype tests are used in the comparison and show that load-deformation process of lattice transmission tower can be predicte accurately with considering all the joint effects.4) The changing process of inner forces and deformation of lattice transmission tower are analysed with considering joint effects, the the infulunce of bolted joint on the lattice transmission tower subject to ground deforamtion are disscussed and the maximum magnitude of ground deforamtion and the failure sequence of members are presented.5) The equivalent model of transmission lines are presented with considering conductor and ground wire suporting effects, and the dynamic response of the lattice tower subject to break of middle and side conductor are analyzed and the infulunce of joint effects on dynamic response are presented.