Experimental Research And Finite Element Analysis Of Circular Hollow Section(CHS) Brace-H Section Chord KY-Joints

In this paper,based on a large number of related domestic and foreign literatures,the 24m steel trusses adopted in the project are used as the object,and the static behavior and influencing factors of the CHS?Circular Hollow Section?brace-H section chord KY joints are studied with experimental research and finite element analysis.The main contents are as follows:?1?Research on full-scale test of tubular jointsDesign the reaction force frame and other loading devices and use hydraulic jacks to load,the full-scale test and analysis of typical tubular joints are carried out.The results show that when the tubular joints reach the limit state,the joint is torn by the weld at the maximum tensile force and the local plastic damage occurred on the upper flange of the chord.The ultimate bearing capacity is 612.9 kN.The stress on the joints between the web members and the tubular joints is complex,resulting in the stress concentration phenomenon.Some regions have entered the plastic state when the load is not large.?2?Finite element modeling method and verificationIn this paper,using ABAQUS finite element software,the unit type,grid size,boundary conditions and loading method of the tubular joints test specimen are proposed.A reasonable finite element model of the joint is established,and the criterion of ultimate bearing capacity is given.The calculation results show that the difference between the ultimate bearing capacity of the tubular joints and the test data is only about 5%.The failure mode and force performance of the finite element analysis are consistent with the test results.It is proved that the finite element modeling method mentioned in this paper is correct and reasonable.?3?Analysis of factors affecting the static behavior of tubular jointsConsidering the three factors,including hidden weld,stiffened plate and geometric parameters,the finite element analysis of tubular joints is carried out.The results show that the internal hidden welds have almost no effect on the failure mode,stiffness and stress distribution of the joints,but it improves the ultimate bearing capacity of the joints.The setting of the stiffened plate of the H-steel chord does not change the failure mode of the tubular joints,but the setting of the transverse stiffeners at both ends improves the ultimate bearing capacity and stiffness of the joints.The failure mode of tubular joints is greatly affected by the geometric parameters.The increase of two parameters of?₁ and?₁ can increase the stiffness and ultimate bearing capacity of the joints.?4?Analysis of hysteretic behaviour and influence factors of tubular jointsIn this paper,the hysteresis curves,skeleton curves and ultimate bearing capacity of the joints are obtained by using the finite element method.The influence of hidden welds,stiffened plates and geometric parameters on the hysteretic behavior of the joints is analyzed.The results show that the failure mode of the tubular joints is consistent with that under static load under the effect of low-cycle reciprocating loads.Compared with no welding,the energy dissipation capacity,ultimate bearing capacity,and secant rigidity of the internal hidden weld joints are all improved.The setting of the chord stiffener reduces the energy dissipation capacity of the joint,but improves the ultimate bearing capacity,the secant stiffness and the deformability of the joint.The changes of geometric parameters?₁,?₁ and?all have different effects on the energy dissipation capacity and ultimate bearing capacity of the joints.The research results of this paper can provide help for the further study of the CHS brace-H section chord joints and also provide reference for the future application of engineering and related specifications.