Study On Bearing Capacity Of Joint With Core Steel Tube In Concrete Filled Steel Tubular Structures

This article is the further research to the new type of column-beam joint of concrete filled steel tubular (CFST), which Prof. Wang Yihong presented. The module experiments are carried out to investigate the mechanism properties such as: the coordinated working performance, major factors that influence the bearing capacity of the joint are the strength of concrete, the bearing capacity of the core steel tube, the quantity and strengths of the ring and vertical short steel bars, and the restraints provided by connected beams. Base on the test results and the principle of inferior limit, the formula for calculating the ultimate strength is established. The result educed by the formula is conservative.The basic mechanism properties are studied by using nonlinear finite element analysis (FEA) of the joint specimens. The results indicate that the result gained by the formula is safe and can apply to calculate the ultimate strength of the joint. The forms of the new type CFST joint have a good coordinated working performance. Since the existence of core steel tube, ring and vertical steel bars, the continuity of the CFST column is preserved and the condition of joint is greatly improved.