Basic Study on Shear Capacity of CFT Members with a Large Width-thickness Ratio of Steel Plate

This study is intended to investigate the shear capacity and shear failure mode of the concrete filled steel tubular (CFT) members with a large width-thickness ratio of steel plate. Six specimens used have a square cross section and 200 or 250 of width-thickness ratio of steel plate. The beam specimens simply supported were tested, in shear-span ratios ranging from 0.75 to 2.0, by a two-point loading method. Only the specimen with 0.75 of shear-span ratio showed a clear shear failure mode. The shear capacities of these specimens amounted to 4.61 times as large as the values predicted by the current codes of CFT members in which the shear capacity assumes to be yielded by only steel section. Discussions are made on the shearing rate of shear strength into steel section and core concrete. And it is suggested that the shear capacity of CFT member may exceed the simply cumulative strength of steel webs and core concrete by virtue of a confinement effect.