Parameters analysis of the behavior of concrete filled circular steel tubular stub columns

According to the elasto-plastic analysis theory for concrete filled tubular steel(CFTS) stub columns with circular section,which was verified by the test results,the behavior of the columns was simulated when loaded to failure,the axial stress-axial stain relations of steel tube,the perimeter stress-strain relations of steel tube and the axial stress-axial stain relations of concrete core were analyzed and the influences of the significant parameters,such as steel ratio,yield strength of steel and strength of concrete on the mechanical behavior of the columns were discussed.The results indicate that the axial stress of concrete core increases greatly and the ductility is improved when steel tube is confined.At the same time,the axial stress of steel tube decreases rapidly for confinement effect.When other parameters are the same,with the steel ratio and the yield strength of steel increasing,the confinement effect of columns is strengthened,and the ultimate strength and the ductility of columns grow.As the strength of concrete increases,confinement effect and the ductility of column are weakened but the ultimate strength of columns grows.