Performance of the High-Strength Self-Stressing and Self-Compacting Concrete-Filled Steel Tube Columns Subjected to the Uniaxial Compression

To improve the compactness of concrete and prevent the debonding between steel tube and concrete core, a high-strength self-stressing and self-compacting concrete-filled steel tube (HSS–CFST) column is introduced. This paper deals with an experimental study on the uniaxial compression of HSS–CFST. A total of 51 specimens subjected to axial compression were investigated. Important variables, including self-stress level, concrete strength, tube thickness, and length-to-diameter ratio, were studied. The failure modes, ultimate bearing capacity, and post-peak ductility were analyzed. The results showed that the use of HSS concrete in CFST yielded a better uniaxial compression performance in comparison with the conventional CFST specimens. An increase of 12.4% in ultimate bearing capacity was observed for an HSS–CFST specimen having a self-stress of 5 MPa. The improvement becomes more pronounced as the length-to-diameter ratio increases. Besides, increasing concrete strength can also contribute significantly to the ultimate bearing capacity, while improvement on the post-peak ductility is not obvious. Furthermore, a numerical analysis considering the self-stressing was carried out, which provided good agreement between the experimental results. Finally, predictive equations specially to calculate the ultimate bearing capacity of HSS–CFST columns were proposed and then validated by the experimental results.