Experimental Research And Finite Element Analysis On The Welded Hollow Spherical Joints Strengthened By Steel Thimble Out Side The Ball

Reinforcement of Welded hollow spherical joints used in truss structure is a practical problem in current project.However,there is no design method and calculation formula for the reinforcement of welding hollow spherical joint in the specification.It may be an effective way to improve the bearing capacity of welded hollow spherical joints reinforced by welding steel thimble outside the joints.(1)A space truss used in a shopping mall was tested,and it is found that the Welded hollow spherical joints need to be reinforced for its insufficient bearing capacity which caused by the minus deviation of the hollow ball.(2)A reinforcement method that welding steel thimble outside the joints was introduced.4 group of(n = 3 specimens)specimens had been made,and an experiment was conducted on these specimens to investigate the feasibility of this method.The bearing capacity of the joints reinforced by welding steel thimble outside the joints under pressure and tension was obtained.And the reinforcement method was verified practical.(3)Finite element model was established by using the ANSYS numerical analysis software.Nonlinear numerical analysis was conducted on both reinforced and unreinforced joints.Adjust the model by comparing the numerical simulation results and the test results,and the relatively reasonable model was obtained.(4)Nonlinear numerical analysis was conducted respectively on the joints with different thickness of the ball and different diameter of the steel pipes by using the reasonable model.The mechanical properties and failure mechanism of the welded hollow spherical joints before and after reinforcement were investigated.Based on the analytical results of the bearing capacity of the joints before and after reinforcement,the empirical formulas of the bearing capacity of the joints strengthened by welded steel pipe was obtained.The results of this study can provide a reinforcement method for the design and calculation of the reinforcement of the joints whose bearing capacity is insufficient due to the minus deviation of ball thickness,corrosion and so on.