Experimental investigation and computational simulation of slender self-stressing concrete-filled steel tube columns

Introducing initial self-stress is an increasingly popular technique to eliminate the disengagement at the interface of steel-tube-confined concrete in CFST. In this study, the axial behavior of slender self-stressing concrete-filled steel tube (SCFST) is investigated in both experimental and computational simulation ways. The experimental study involves 13 slender SCFST columns with various initial self-stress, length-to-diameter ratio, concrete strength, and steel tube thickness. A modified fiber-based computational method, which is capable of simulating the initial self-stress, is exploited to capture the compressive response of slender SCFST columns. The results demon-strate that the initial self-stress averagely improves the axial strength by 31.8%, while reducing the deformability of the slender SCFST columns. The decrease in ductility index is about 25.1%. The benefit of self-stress decreases as the length-to-diameter ratio increases. Prediction models for ultimate strength are proposed based on the experimental and numerical results, and accurately capture the compressive properties of slender SCFST columns.