Axially Loaded Thin-Walled Square Concrete-Filled Steel Tubes Stiffened with Diagonal Binding Ribs

Diagonal binding ribs made of perforated, thin-walled steel plates and welded to the adjacent sides of the steel tube of a square concrete-filled steel tubular (CFST) column are expected to delay the local buckling of the steel tube and better confine the infilled concrete. In this paper; 21 CFST stub columns were tested under axial compression to investigate the effects of the diagonal ribs. Particularly, four specimens with high-strength concrete were tested. Test results indicated that the continuous confinement from the diagonal binding ribs could effectively improve the composite effect of the stiffened square CFST columns, while the discontinuous ribs reduced the strength little but reduced the ductility to some extent. The stiffened specimens with high-strength concrete had moderate ductile capacity although they behaved less ductile than the specimens with normal-strength concrete. Finally, a load-carrying capacity calculation method was proposed and compared with design guidelines.