Simulation And Experimental Study On Mechanical Properties Of Transmission Tower Main Member Joint

Transmission tower are typical spatial truss structure,which are commonly composed of equilateral angle steel.The main member is main force components of the transmission tower.In the construction of transmission tower main member joint,the bolt connection is widely used because of its convenient installation and low cost.However,due to the small preload,joint is prone to slippage,which will affect the structure of the internal force distribution and the overall stiffness characteristics.Therefore,studying the mechanical properties such as the joint slippage and the semi-rigidity of the bolted joints is of great theoretical value and practical significance to improve the analysis and design of the transmission tower and to ensure the long-term stable operation of the large-scale power grid.In this paper,eight kinds of typical bolted joints in transmission tower are studied,and the full-scale finite element simulation models are established.The simulation models simulate the tensile failure process of the joints,and the simulation models are verified through the real-type experiment.In the end,the finite element simulation results and the real-type experimental results are used to deeply analyze the mechanical properties of the joints such as the joint slippage and the semi-rigidity of the connection as well as the failure load.This paper mainly draws the following conclusion.Through the finite element simulation and real-type experiment of the main member joint,the experimental joints are basically consistent with the simulation results in terms of failure mode,load-deformation curve and failure load,and experimental results verify the accuracy of the finite element model.In this paper,the simplified model of the finite element simulation load-deformation process fitting can describe the connection slip process of the joint well.The model is easy to use and the function is continuous.The main member joints in the actual tower exhibit semi-rigid characteristics,and the variations in bolt hole diameter,number of bolt rows,angle limb width,and angle of limb thickness affect the initial stiffness of the joint.For the failure mode in which the bolt is sheared,selecting the punching method can increase the damage load of the joint.Conversely,for the joint that breaks in the form of tearing at angle steel limb wall,the choice of drilling method can increase the damage load on the joint.Therefore,a reasonable choice of bolt hole processing methods can not only save costs,but also maximize the carrying capacity of joints to ensure the safe operation of transmission lines.