Load-bearing Capacity Of Welded Hollow Spherical Joints Strengthened With Steel Casing

Grid structure is one of the main forms of spatial structure and is widely used in various large-span buildings.The welded hollow spherical joint is one of the most widely used joint forms in the space grid structure.On most grids,there are multiple rods connected to a spherical joint,and the rods only bear pressure and tension.Under the action of complex environment and load,as the service life of welded ball joints increases,the bearing capacity is weakened due to material corrosion or the safety reserve is insufficient due to load changes.The replacement of joints often requires higher engineering costs.And its difficult construction process also has certain safety hazards.Therefore,necessary reinforcement of nodes with insufficient bearing capacity is a relatively economical and reasonable method.It is a simple and effective way to reinforce the steel sleeve at the end where the steel pipe is connected to the hollow ball.Therefore,this paper adopts the method of steel casing to strengthen the welded hollow ball,and conducts numerical analysis and experimental research on the ultimate bearing capacity of the welded hollow ball joints before and after reinforcement.The main research contents are as follows:1.Two methods are used to study the failure form and bearing capacity of the steel casing before and after the reinforcement and welding of the hollow spherical joint under pressure load.One is to use the test method to select two typical ball joints for loading test on the compression testing machine;the second is to use finite element analysis to simulate the welded hollow spheres of the same size.The failure modes and load-displacement curves of the welded hollow sphere joints before and after reinforcement before and after the reinforcement are obtained respectively;at the same time,the compression force of the welded hollow spheres before and after reinforcement is obtained according to the load-displacement graph.Bearing capacity;by comparing the measured value of the test and the finite element simulation results,the accuracy of the finite element model is analyzed and verified;and the failure mode of the steel casing before and after the hollow sphere is reinforced and welded according to the test failure diagram and Mises stress cloud diagram.2.Based on the general finite element analysis software ANSYS,using hexahedral solid elements,multi-linear isotropic strengthening stress-strain relationship and Von-Mises yield criterion,while considering geometric nonlinearity and material nonlinearity,a steel casing reinforced welded hollow spherical joint is established Numerical analysis of the compressive and tensile bearing capacity of welded hollow spherical joints before and after reinforcement is carried out.3.The main parameters that affect the improvement coefficient of the compressive bearing capacity of the steel casing reinforcement welded hollow ball are the thickness t_r,the height h_r,and the diameter d_r of the steel casing.Use the general finite element analysis software ANSYS to study the influence of steel casing thickness t_r,height h_r,and diameter d_r on the bearing capacity performance of welded hollow spherical joints;analyze the parameters of the increase coefficient of the compressive bearing capacity after reinforcement,The results are fitted;the calculation formula for the compressive bearing capacity of steel casing reinforced and welded hollow spherical joints is proposed.Can provide reference for related engineering applications.