Study On Mechanical Behavior Of T-shaped Concrete Filled Steel Tubular Columns With Steel Side Joints

Shaped concrete-filled steel tubular column can make the column and the filling wall is thick,to avoid the indoor prism,with good use of the building function.However,the types of beam-column joints of special-shaped concrete-filled steel tubular structures are few and difficult to meet the needs of practical engineering diversification,and the design method can not fully meet the needs of engineering applications.In this paper,a new type of side-plate connected T-shaped concrete-filled steel tubular column is proposed,which is based on the fact that the research results of the special-shaped concrete-filled steel tubular column-steel beam connection node are not systematic,the mechanical properties of the joint and the construction convenience can not be two and the existing node type is less.Steel beam node form,and the use of numerical simulation and theoretical analysis of the combination of the mechanism of its mechanism of the system.Firstly,ABAQUS finite element software is used to establish the fine finite element model of T-shaped concrete-filled steel tubular columns and steel girder joints.Secondly,the numerical simulation is carried out to study the stress mechanism and force transmission path of nodes.Finally,the parameters of the node expansion analysis,the proposed node optimization design model,the specific work of the following three aspects:(1)The tectonic form of the T-shaped concrete-filled steel tubular column-steel beam is proposed,and the fine finite element model of the joint is established.In order to verify the validity of the model,a finite element model of six combined T-shaped concrete-filled steel tubular columns with the same size and material properties was established,and the numerical simulation of the axial compression was carried out.The results show that the finite element model of the combined T-shaped concrete-filled steel tube(CFST)is in good agreement with the experimental curve.It is proved that the boundary condition,unit selection,meshing and related parameters are reasonable in the finite element model.Finite Element Numerical Simulation Analysis of Connecting T-shaped Concrete Filled Steel Tubular Column-Steel Beam Joints.(2)Monotonic loading simulation of the fine finite element model of the node.The boundary constraints and loading modes of the simulated nodes in the experimental state are applied,and a constant axial force is applied to the top of the column and a monotonic load is applied at the beam end to analyze the stress distribution and deformation process of the joint under the combined action of the load.The results show that the confinement effect of the side plate on the T-shaped concrete-filled steel tubular column is obvious.The failure mode of the joint is mainly due to the yield failure of the unbonded beam of the connecting plate,the slight increase in the tension zone of the concrete-filled steel tubular column and the obvious damage The When the steel girder enters the yield state,the concrete-filled steel tubular column and the node area are still in the elastic stage and have good rigidity,which indicates that the node satisfies the design requirements of "strong column weak beam and stronger node".(3)The parametric expansion analysis of the fine finite element model of the node is carried out.The effects of axial compression ratio,material properties,thickness ratio of steel pipe,strength of connecting plate and length of side plate are considered,and the influence of the stress on the mechanical performance of the joint is studied.The results show that with the increase of the thickness of the side plate and the thickness of the connecting plate,the stiffness of the joint becomes larger;the thickness of the steel beam,the strength of the steel pipe itself and the strength of the connecting plate reach a certain value and then will not affect the stiffness of the joint.Pressure ratio,core concrete strength grade,side plate strength and steel pipe width and thickness ratio have no obvious effect on the mechanical properties of the joint;the thickness of the side plate is reduced,the stiffness of the joint increases,and there is no obvious change after a certain range;the smaller the length of the connecting plate,The bigger ones.