Study On Hysteretic Behavior And Optimization Of Cross Joint With Expanded T-Stub Connectors In Steel Frame

The steel structure has the advantages of light weight,high strength,good ductility,etc.,so the steel frame structure system is widely used in the construction industry,where the beam-column connection node determines the overall performance of the steel frame.Whereas in the 1994 Northridge Earthquake in the United States and the Hanshin Earthquake in 1995 in Japan,the traditional steel frame joint failure mainly represented the brittle fracture failure at the beam-column weld and the shear failure of the joint domain,the new ductile steel frame beam-column connection node Research is getting more and more attention.In the process of research,the problem of node domain destruction becomes more prominent,so the strengthening of node domain is also more important.In this paper,the T-stub member is connected to the center column node of the steel frame as the research object,combined with the previous research results,the T-stub connector of the center column node is improved into a wing-expanded T-stub connector.Analysis of hysteretic performance and mechanical performance of the node domain of the column joints in the steel frame connected by the piece.The specific research content and research results are as follows:(1)Experimental research and numerical simulation analysis of T-stub connecting plates:Through unidirectional tensile tests and finite element numerical simulation considering contact nonlinearity,the mechanical properties of T-stub connecting plates and bolts with different parameters were studied.The results show that:The increase in the length of the flange plate inner plate will reduce the bearing capacity of the test piece;the increase in the length of the flange plate outer plate has no significant effect on the mechanical properties of the test piece;as the diameter of the bolt increases,the constraint of the bolt on the test piece increases The bearing capacity of the piece increases,but the prying force increases accordingly;the thickness of the flange plate can reduce the deformation of the specimen,and the failure form of the specimen shows that the bolt is damaged by tension.The comparison between the test and the numerical simulation results shows that the change trend of the test and the finite element simulation results are similar and the error is small,which verifies the validity of the finite element nonlinear analysis model of the T-stub connecting plate and the feasibility of the contact nonlinear modeling method.(2)Hysteresis performance analysis of T-stub connected to the column nodes in the steel frame:by establishing a nonlinear finite element analysis model of ordinary and expanded-wing T-stub connected to the column nodes in the steel frame to study the effect of low-cycle reciprocating loads The hysteretic performance of the lower center column node and the bearing performance of the node domain,the research results show that the initial stiffness of the T-stub connecting node with a 25 mm widened wing width is increased by 6.2%and the ultimate bearing capacity is increased by 2.3%,The ductility coefficient is increased by 8.1%,the equivalent viscous damping coefficient is increased by 7.9%,the shear rotation angle of the node domain is increased by 50.5%;the initial rigidity of the T-stub connection node with a 40 mm widened wing is increased compared with the ordinary type test piece 10%,ultimate bearing capacity increased by 3.3%,ductility coefficient increased by 16.3%,equivalent viscous damping coefficient increased by 8.8%,and nodal domain shear rotation angle increased by 61.9%.It can be seen from this that the use of expanded-wing T-stub can effectively improve the hysteresis of the central column node and the bearing performance of the node domain,but at the same time also increase the shear deformation of the node domain.(3)Optimized analysis of the node domain reinforcement method of the center column node:Based on the stress conditions of the above node domain,a finite element analysis model of the steel frame center column node with different reinforcement methods in the node domain was established,and the hysteretic performance and Force performance of node domain.The results show that the addition of diagonal cross-shaped stiffeners and diagonal stiffeners in the node domain has a significant effect on improving the bearing capacity of the node and reducing the shear deformation of the node domain.The aspect is lower than the diagonal stiffener,but the effect is significant in reducing the deformation of the node domain.