THE AXIAL COMPRESSION BEARING CAPACITY OF THE CONCRETE FILLED STEEL TUBULAR COLUMN-BEAM JOINT WITH THE COLUMN TUBE DISCONTINUOUS IN JOINT ZONE

The mechanics characteristic of the concrete filled steel tubular column-beam joint in which the column tube is discontinuous under axial compression is analyzed. The main influence factors are figured out, which include the strength of concrete, the ratio of the area of the joint section and the area of the steel tube, the amount of the steel ring bars and the height of the joint. Based on the theory of local compression, as well as according to the confined concrete theory, the concept of gradual superposition of the confinement from multilayer steel ring bars to the core concrete is presented, the joint height coefficient is introduced, and then the formula for calculating the ultimate axial capacity is put forward. The comparison between the results of calculation and experiment shows that they are consistent with each other.