Biaxial bending behavior of concrete filled square steel tubular stub columns using high strength materials

In this study, the effects of loading direction on the flexural behavior of concrete filled square steel tube (CFT) are experimentally studied. The selected test parameters are loading direction and eccentricity of axial load. As the result, It was indicated that the flexural stiffness and axial stiffness of CFT column subjected to bi-axial bending could be evaluated by the equivalent stiffness of the concrete elastic stiffness with that of the steel tube regardless of the loading direction, the same as the case under the uni-axial bending. The ultimate strength curve of CFT column subjected to the bi-axial bending was ascertained, and its evaluation formula was proposed