Parameters analysis of the behavior of circular concrete-filled steel tube stub columns

This paper presents parameters analyses on circular concrete-filled steel tube (CFT) stub columns under concentrically loaded conditions. According to the Elasto-Plastic Analysis Theory for circular concrete-filled steel tube (CFT) stub columns verified by test results, the behavior of the stub columns was simulated with the stub columns loaded to failure. The axial stress-axial strain relationship of the steel tube, the perimeter stress-axial strain relationship of the steel tube and the axial stress-axial strain relationship of the concrete core were analyzed. And the influences of the significant parameters, such as steel ratio, yield strength of steel, strength of concrete on the confinement of the concrete core and compression shared by the steel tube were discussed. Results related to the analyses and discussions indicate that: for the confinement of the steel tubes, axial stress of the concrete core increases greatly with its ductility improved, and axial stress of the steel teel tube decreases rapidly. When other parameters are the same, with steel ratio and the yield strength of steel increasing, the confinement effect of the columns are strengthened, and the ultimate strength and the ductility of the columns grow. With the strength of the concrete increasing, confinement effect and the ductility of the columns are weakened but the ultimate strength of the columns grows.