| Concrete-filled steel tube structure can adapt to the needs of large span,large height and large load in modern engineering,and is more and more used in building structures.CFST column-ring beam joints can be connected with frame beams in any direction due to their non-directionality,and the force transmission mechanism is clear and reliable,which is widely used in building structures.However,the existing results mostly study the performance of beam-column joints in the middle storey,and the research on beamcolumn joints in the roof storey with large overburden pressure is not perfect.In this paper,experiments similar to the research objects in this paper are selected from the existing literatures,and finite element software ABAQUS is used for simulation analysis and comparison,which verifies the applicability and reliability of finite element modeling.Then,based on CFST(Concrete-Filled Steel Tube)column-RC ring beam joint on the roof storey of Exhibition Hall No.1 of Lin Cang Asia-Micro Convention and Exhibition Center,ABAQUS is used to analyze the parameters of the joint,and the mechanical properties of the joint under cyclic load are studied under different depthheight ratios,column cap heights and the density of steel pipe welding studs.The results show that the material constitutive relation and contact relation selected in this paper can well reflect the actual mechanical properties of the joints in the test,and have good accuracy.The mechanical properties of each model under cyclic load are analyzed from hysteretic curve,skeleton curve,energy consumption,stiffness and strength degradation,etc.The larger the height(depth-height ratio)of steel column extending into the ring beam,the stronger the lateral deformation of frame beam concrete under cyclic load is restrained by steel tubes,the greater the energy dissipation by the joints,the greater the bearing capacity and stiffness,and the better the mechanical properties of steel bars.The higher the cap height,the greater the energy dissipation coefficient and energy dissipation,and there is no significant difference in other models with different cap heights.Wall-welded studs of steel tubes can effectively assist the shear ring to transmit force,and the joints welded with thin and dense studs have better energy dissipation capacity,and other indexes are not much different among different models.The displacement-stiffness function fitting is carried out,which shows that the joint stiffness is degraded in the form of power function.Finally,the research results of this paper are summarized,and some suggestions for the existing problems are put forward. |
