Eccentric compression behaviour of diagonal rib-stiffened thin-walled square concrete filled steel tubes

Abstract

Thin-walled square concrete filled steel tubular (CFST) members have attracted more attention in practice because of less steel consumption, high construction efficiency, and convenient arrangement for furniture or curtain wall. Compared with circular members, the local buckling of thin-walled square CFST members is a big concern since tube buckling often results rapid strength and ductility degradation. So in this investigation, diagonal ribs were welded on the internal tube corners to improve the performance of square CFST members. Nine diagonal rib-stiffened square CFST specimens, with large width-to-thickness ratio B/t=100, were experimentally investigated under eccentric compression. The main test parameters included column slenderness ratios (λ=13.9, 34.6, 55.4) and loading eccentricities (2e/B=0, 0.25, 0.50, 1.00). Detailed finite element models were established and verified. The composite effect of the stiffened column was elaborated through combining test results and the finite element analysis, followed by feasibility of column–column connection details and parametric studies. Finally, design methods for calculating the member resistances subjected to axial and eccentric compression were proposed.