EQUIVALENT UNIAXIAL CONSTITUTIONAL RELATIONSHIP FOR THE ENCASED CONCRETE OF T-SHAPED STEEL TUBULAR WITH BINDING BARS

The behaviors of T-shaped concrete-filled steel tubular (CFT) stub columns subjected to axial compression were experimentally investigated, including 11 specimens with binding bars and 5 ones without binding bars. The effects of the spacings and diameters of binding bars, thicknesses and strengths of steel plates, and section sizes on the failure modes and bearing capacities are discussed. The results indicate that the buckling modes of the steel plates are changed, the local buckling of the steel plates is delayed, and the bearing capacity and ductility of the T-shaped CFT stub columns are improved by setting binding bars. Based on a reasonable assumption, the T-section is divided into a square and three rectangular sections, in which the rectangular sections have binding bars while the square section has no one. The constitutional relationship of confined concrete is referred to build the equivalent uniaxial constitutional relationship for the core concrete of each section with clear mechanic concept. The results of load versus strain curves calculated by the proposed constitutional relationship are in good agreement with the experimental ones.