Study On Mechanical Behavior Of The Steel Tube Confined ConcreteColumn Ring Beam Joint With Shear Ring

In advantages of easy construction and low cost, the steel tube confined concrete column ring beam joint with shear ring has been widely used in the connection between steel tube confined concrete column and reinforced concrete beam in the steel tube-confined concrete structures in recent years. However recent studies were all on the vertical steel tube-confined concrete column ring beam joint with shear ring, lack of study on the decline steel tube-confined concrete column ring beam joint with shear ring, in order to analysis the seismic behavior, the mechanics mechanism and the ultimate failure mode of the decline steel tube confined concrete column ring beam joint with shear ring, two two-thirds scale decline steel tube confined concrete column and ring beam combinations according to Sichuan broadcasting building were tested under cyclic loading. The experimental results indicated that the decline steel tube confined concrete column ring beam joint with shear ring could effectively transfer the moment and shear from the frame beam through reasonable design of the ring beam; Whether the failure occurred in the frame beam or in the ring beam, it could still make the combinations have sufficient bearing capacity and displacement ductility; Due to the independence of bearing capacity between the decline steel tube confined concrete column and the ring beam, the failure of the ring beam would not influence the longitudinal bearing capacity of the decline column.While there was no study on the steel tube confined concrete column ring beam joints with shear ring under direct shear, lack of basis to analysis the problems such as the ultimate bearing capacity, the mechanics mechanism, the sliding of ring beam relative to steel tube and the ultimate failure mode of this joint which were concerned in engineering circles , 3 steel tube confined concrete column ring beam joints with shear ring were tested under direct shear and simulated through the finite element program ABAQUS. The experiment and simulation results indicated that the steel tube confined concrete column ring beam joints with shear ring had high bearing capacity and small slip under direct shear, the reason why the specimens reach the ultimate bearing capacity and slip was not the concrete local failure under pressure which under the shear ring but the form of the failure surface, the failure surface was compounded by two parts, one part was the surface between the ring beam and steel tube upon the first shear ring ,another part was the concrete surface between the stirrup of ring beam and steel tube, the ultimate bearing failure mode and the calculation of bearing capacity awaited further tests and analysis.