Concrete column encased by double steel tubes (WSC) which are arranged concentrically is studied. Inner concrete is prestressed by prestressing bar arranged at the center of column section. Tensile force is canned by inner concrete, prestressing bar and outer steel tube, while compressive force is carried by inner concrete confined by both double steel tubes and outer concrete.
In this study mechanical property of WSC subjected to axial forces is clarified by experiment and finite element analysis. The dynamic analysis of the frame braced by concrete columns which is encased by double steel tubes was also conducted. The frame, which is nonlinear elastic system, was observed to be superior to elasto-plastic and linear elastic systems.