Research On Mechanical Properties Of Beam-column Joints With Upper Ring Plate And Lower Inner Diaphrag

The beam-column joint is a very important part in the high-rise residential building with steel structure.The joint should have good mechanical properties such as stiffness,strength,ductility and energy dissipation capacity,so as to satisfy the effective transfer of load between members.In practical engineering,external and external ring plate joints are widely used in steel structure high-rise residential buildings.In order to solve the problems that the lower ring plate of the outer ring plate joints of concrete-filled steel column H-type steel beam occupies indoor space and affects the appearance due to its large size,a new type of beam-column upper ring plate and lower inner partition type joints is proposed in this thesis.In this thesis,the mechanical properties of the upper ring plate and lower inner partition plate joints of the beam column are studied by combining theoretical analysis and numerical simulation.In view of the difficulty of concrete placement for this joint,finite element method ABAQUS was used to study the mechanical and seismic properties of specimens under static and reciprocating loading,and the effects of different internal partition parameters on bearing capacity,rotational stiffness and seismic performance were studied.The following conclusions were drawn:(1)The new concrete-filled steel tubular column designed in this thesis meets the design principle of "strong joints and weak members" with the inner diaphragm joints under the upper ring plates of H-shaped steel beams.The joint has sufficient bearing capacity and deformation capacity under the action of bending moment and shear force.(2)By using ABAQUS finite element software,the static loading analysis of the nodes is carried out,and the following conclusions are drawn: with the increase of the opening area of the inner partition,the flexural capacity and initial rotational stiffness of the nodes decrease;When the connecting plate is welded on the micro inner diaphragm,the flexural capacity and initial rotational stiffness of the node are increased,which can effectively prevent the failure of the inner diaphragm without force due to too large aperture.The increase of the thickness of the micro ring plate can improve the flexural bearing capacity and initial rotational stiffness of the joints.The greater the thickness of the micro ring plate,the more prone to yield failure of the beam end.When the beam is arranged in the short side direction,the flexural stiffness of the joint is maximum,and the failure of the joint is the failure of the beam end.(3)By using ABAQUS finite element software,the parameters related to the internal partition of the node were changed to analyze the seismic performance of the node.The results show that the concrete filled steel-H-shaped steel beam with upper ring plate and lower inner partition plate has good seismic performance,which can give full play to the advantages of the outer ring plate and the inner partition plate,and avoid the disadvantages of other joint forms,and solve the prominent problem of the lower outer ring plate.It is worthy of large-scale popularization and application.(4)Parameterization of the joints is studied,and some suggestions are put forward for their application: when the beam is arranged at the edge of the weak axis of the steel pipe column,the thickness of the inner diaphragm connecting plate should be 40-60mm;The thickness of the micro ring plate should be 2-3 times the thickness of the beam flange;When the beam is arranged in strong axis,the inner partition board with large opening area may not be equipped with the inner partition connecting plate.