| Rectangular concrete-filled steel tubular column-concrete beam composite structure has excellent mechnical and seismic performance,and the structure shape is regular,which is conducive to the connection of beam-column joints and the layout of the building.Rectangular concrete-filled steel tubular column-concrete beam joint is one of the key technologies of the structural system,which has an important impact on the seismic performance of the structure.However,at present,the connection form and stress situation between rectangular concrete-filled steel tubular column and concrete beam are complex.The mechanical behavior of staggered and oblique joints is different from that of conventional nodes.However,there are few related research on design methods and seismic performance.In view of this,this paper take Zhenjiang Suning Square project as the background,and the methods of experimental research and numerical simulation are used in this paper,the seismic behavior of a new type of overlapped rectangular CFST column-concrete beam joint is studied,the main research contents and results are as follows:1.The low cyclic load test was carried out on the joints of rectangular concrete concrete-filled steel tubular column and concrete beam,with the cross height of beams and the beam-column angle as experimental parameters.The results show that:plastic hinge occurs at the beam of joint,the deformation of CFST column and core area is small,the hysteretic curves of the joints are full,the stiffness degration is uniform,and the ductility of joints can meet the application requirements of engineering,but the energy dissipation capacity is relatively poor.As the staggered height of left and right beams increases,the bearing capacity of the joints is basically unchanged,the stiffness degration rate decreases.With the increase of beam-column angle,the bearing capacity and stiffness degration speed of the joints remain basically unchanged.2.ABAQUS finite element software was used to establish the numerical analysis model of rectangular concrete-filled steel tubular column-concrete beam joints.The test results were used to verify the simulation,the failure forms,concrete damage and joint crack distribution rules of the specimens were analyzed.The influence of staggered height of beams and beam-column angle to joints under beam hinge failure model are analyzed.3.The beam-column bending capacity ration k_m is taken as parameter,the damage distribution of concrete,the stress distribution law of reinforcement and shear force of joint core area is studied.The limit k_m of joint failure model is determined,and the discrimination method of joint is proposed.4.Based on the failure discrimination method of joint,a numerical analysis model of rectangular concrete-filled steel steel tubular column-concrete beam joints with shear failure in the core area is established.The influence of the staggered height of left and right beam and the beam-column angle on the seismic performance of joints is studied,the force mechanism between concrete and steel in core area is analyzed.The results show that:As the staggered height of left and right beams increases,the capacity,stiffness and energy-dissipating capacity first increases then decreases and finally stabilizes.As the beam-column angle increases,the bearing capcacity and stiffness of the joints gradually decrease.The concrete and steel plate in the core area transfer loads through the mechanism of compression strut and oblique pressure zone.On the basis of experimental research and numerical simulation,the design proposal of the joint is put forward.The research results can provide reference for the engineering application and theoretical analysis. |
PDF Full Text Request