The Ultimate Bearing Capacity Of The K-type Square Cfst Study

K-joints with concrete-filled square steel tubular (CFST) is a new type joint and the study on structural behavior of it is still not perfect. After acquainting myself with the research status with regard to this CFST joint about the experimental method, mechanic performance, finite element theory, several aspects will be studied in this thesis: .(1) The static experiment about six K-joints with CFST and one K-joint with square steel tubular is carried through. The static behavior of K-joints with CFST is gained and followed by comparison analysis on the two kinds of joints.(2) On the basis of analysis the constitutive relationship, failure criterion and element type, finite element model of K-joints with CFST is established.(3) Comparison of finite element results with experimental results shows that the finite element model can simulate the joints fairy well. Then effects of geometry parameters on the ultimate capacity of joints are discussed and the available ranges of these parameters are obtained.(4) Formula for calculating the ultimate strength of K-joints with CFST is proposed. The results of the formula can meet with the experimental results.Based on the model test, analyzed in finite element program, the thesis gives credible data to the design of K-joints with CFST. The results of this thesis are also aimed at offering convicting evidence for the coming Technical Specification for Structures with Concrete-Filled Rectangular Steel Tube Members.