Unified Solution of the Ultimate Bearing Capacity for Stiffened and Thin-walled Square CFST Short Columns Under Axial Compression

Directed against the stiffened and thin-walled square concrete-filled steel tubular (CFST) short columns, the paper simplifies the square CFST columns into the circle ones by introducing the strength reduction coefficient of concrete and the equivalent constraint reduction coefficient. On the basis of the unified strength theory, the united solution of the ultimate bearing capacity for square CFST columns is deduced after considering the influence of strength-differential in tension and compression and intermediate principal stress. Some influencing factors are also analyzed in the paper. Through comparing the results of proposed formula with that of experiments of relevant literatures, the rationality of proposed formula is proved. The solution may provide theoretical references for the study of the ultimate bearing capacity for stiffened and thin-walled square CFST short columns.