Study On Mechanical Properties And Mechanical Mechanism Of Non-Welded Semi-Rigid Joints Of Small Section Beams And Columns

At present,small-section square steel pipe columns and light high-frequency welded I-beams are used as the main components of the load-bearing structure.In the middle and low-rise steel frame residential building structure system,the beam-column joint as a force-transmitting hub is a part of the steel frame structure.In order to ensure the effective transfer between the components,it needs to meet the strong strength and rigidity in design.The mechanical properties of the stability,energy dissipation and other seismic mechanical properties are directly related to the overall reaction of the structure,which is the key in the design of steel frame structure.Different from the traditional welding method,based on the idea of ??the assembled structure,the high-strength bolts are used to bolt the square steel tube column and the H-shaped steel beam through the end plates with high-strength bolts,while satisfying the "strong node,weak member".It is also possible to improve the synergy of the overall deformation of the member.Through low-cycle reciprocating load test,combined with theoretical calculation and finite element simulation,the failure characteristics,hysteretic behavior,bearing capacity degradation,stiffness degradation law,energy dissipation performance,ductility performance,and strain variation of the joint domain are analyzed.Systematic research on mechanical properties.The main research work and results are as follows:On the basis of extensive review of relevant literatures at home and abroad,the research status of steel columns,steel beams and beam-column joints is comprehensively understood.The characteristics of beam-column joints of semi-rigid connections are systematically classified and the beams and columns are The analysis model of the node is discussed.Through the quasi-static test of three sets of 16 T-shaped square steel tubular columns-H-beam beam joint specimens,whether the concrete is filled with concrete in the square steel tubular column,whether there is a hole in the beam web,whether there is a hole in the beam web,and whether there is a flange at the beam flange Reinforce the plate,change the thickness of the end plate of the contact surface of the beam and the column,change the thickness of the square steel pipe column wall,whether the concrete is poured into the square steel pipe column and add the partition plate,whether the square steel tube concrete column is attached with the plate and the end plate lengthens,and change the thickness of the beam flange The eight variables are used as the variation parameters.The failure characteristics,hysteretic behavior,bearing capacity degradation and stiffness degradation of the concrete-filled steel tubular column-H-beam combination are systematically studied by applying the low-cycle reciprocating load test at the beam end.Mechanical properties such as energy dissipation performance,ductility performance,and strain variation of the node domain.The test results show that the concrete pipe is filled with concrete and the partition is added,the web of the beam has no opening,the reinforcing flange of the beam flange,the thickness of the square steel pipe column,the square steel tube concrete column and the slab and the end plate lengthening,the beam flange The component nodes with thickness and other measures have the advantages of high bearing capacity,good energy consumption,large stiffness and good ductility,and basically conform to the seismic concept of “ strong columns,weak joints,strong joints and weak members”.According to the results of the quasi-static test,the hysteresis rule and the restoring force characteristics of the square steel tube column-H-shaped steel beam are analyzed.The four-fold line skeleton curve of the steel pipe column-H-shaped joint is obtained by the test fitting method and the dimensionless treatment.Regression analysis is carried out on the data under low-cycle reciprocating load to obtain the stiffness degradation law at different stages,and the hysteresis rule is mathematically described.Based on this,a four-fold line restoring force model suitable for square steel tubular column-H-shaped steel beam is proposed.The rationality of the proposed restoring force model is verified by comparing the calculation results with the experimental results,which provides a certain dynamic analysis for the steel structure.Reference value.The finite element analysis model of the specimen joint under low-cycle reciprocating load is established by using the square steel tubular column-H-beam combination joint specimen as the model.The model considers material nonlinearity,contact nonlinearity and geometric nonlinearity.Square steel pipe column and plate,square steel pipe column wall and high-strength bolt,H-shaped steel beam end plate outer side and plate,beam end plate and high-strength bolt,screw and bolt hole wall interaction and other factors,through the node test piece Perform solid modeling and meshing,and properly simulate the boundary conditions and loading methods of the experiment.The simulation analysis of the force of the joint is carried out.The analysis results are compared with the experimental results.It is found that the degree of coincidence is high.On this basis,the stress state of each component of the node domain is analyzed.