| As a new structure,the special-shaped concrete-filled steel tubular column structure not only has the advantages of both steel structure and concrete,but also achieves the effect of indoor non-exposed columns,and then has being developed rapidly in recent years.Shaped steel tube concrete column-steel beam joints usually adopt outer ring plate joints,which affect the building function due to the existence of outer ring plates.Aiming at the problem that the outer ring plate of the special-shaped concrete-filled steel tubular column-steel beam joint affects the using function of the building,and considering the requirement of fabricated construction as well,we presents a new type of special-shaped concrete filled steel tubular column-steel beam connecting joint in this work.The wall thickness of the tubular column in joint area is increased as an alternative construction measure to replace the outer ring plates.On the other hand,the z-shaped cantilever beam is used to connect the joint and the steel girder,its one end is welded with the joint,and the other end connected with the girder with high-strength bolts,the advantage is that there is no field welding and it is convenient to achieve the assemblage construction.The finite element software ABAQUS is employed to carry out the quasi-static analysis of the new type joint and the corresponding outer ring plate joint under the action of low cyclic reciprocating load.The specific research contents are as follows:(1)This paper introduces the cross-section forms of various concrete-filled steel tubular columns and the connection methods of their joints,summarizes the research on various concrete-filled steel tubular column-steel beam joints at home and abroad,and puts forward new research topics to solve existing problems.(2)In order to improve the calculation accuracy of the finite element analysis simulation and reduce the computational cost,the setting of the same parameters and the selection of different method techniques for all models are explicated in detail,including the selection of material constitutive,exactly meshing process,analysis of step definitions,boundary conditions and load application.It also focuses on the settingof contact and constraint relationship between different components and different materials,analyzes the influence of penetration and gap between the master surface-slave surface on the calculation results,and the simplified consideration of binding and embedding between components.(3)By taking the mid column,side column and corner column joints in the frame structure as the research object,a total of seventeen joint specimens in the form of three special-shaped column sections are designed,which are four cross-shaped joints,four T-shaped joints,nine L-shape joints.The ABAQUS finite element is used to model them.The whole process of the force of each joint model under low-cycle repeated loading are analyzed.Based on the hysteresis curve and stress nephogram,the skeleton curve,bearing capacity,secant stiffness,ductility and energy consumption of each joint are calculated,and the stress deformation and failure characteristics of each joint are compared and analyzed.(4)The results show that,each new type of joint has a full hysteresis curve and good working ductility,which is superior to the outer ring plate joint in terms of bearing capacity,plastic deformation and seismic energy consumption.By increasing the thickness of the pipe wall of the joint area and the staggered arrangement of drawing plates,the rigidity of the steel pipe and the bearing capacity of the joint are increased,the force of the joint domain is improved,and the occurrence of the torsional deformation of the L-shaped steel pipe and the lateral displacement of the steel beam is reduced or avoided.The new joint can fully utilize the energy dissipation capacity of the joint,which depends on the slip and buckling deformation of the Z-shaped cantilever beam splicing section,and it is convenient to achieve the assemblage construction.Finally,the follow-up research work and precautions about the new joint are proposed. |
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