抄録
CFT (Concrete Filled Steel Tubular members) has attracted much attention because of its structural superiority. However, the increase of weight by filling with concrete inside is one of problem associated with CFT. Thus in this study, to reduce the self-weight of CFT, CFDT (Concrete Filled Double-Skin Steel Tubular members) is proposed particularly for higher bridge piers. The purpose of this study is to clarify the influence of the thickness of outer and inner steel tubes on the bending characteristics by the cyclic loading test and the analysis. As a result, it is shown by the cyclic loading test that CFDT has higher bending strength and energy absorption than CFT of the same weight. CFDT without inner tube has sufficient bending strength, but after the crush of the concrete, its ductility declines like only outer tube. By the constraint effect of concrete, buckling of inner tube is prevented, so the thickness of inner tube can be thin. For reasonable structure, it is effective to make the outer tube thicker than inner tube.
