Axial load behavior of CFT columns assembled with rectangular wave-shaped ribs

Abstract

To solve defects caused by welding, a rib assembled CFT column was developed and the central compression performance, including the ultimate compressive strength, was evaluated through actual experiments. The results indicated that the internal ribs of this CFT column effectively suppressed local buckling, thereby enhancing the concrete confinement effect, and ultimately increasing the ultimate compressive strength. This effect was maximized when the rib specifications met a certain value, and it enabled the CFT column to achieve an equivalent level of axial stiffness and ductility compared to conventional CFT columns. Despite its assembly from multiple segments, the CFT column demonstrated high integrity, proving that the cross-sectional area of the steel tube could be applied according to current codes. The difference in concrete compressive strength due to the concrete confinement effect, which depends on the aspect ratio of the rib, was confirmed to be due to the effective confined area ratio (ke). Therefore, a design model for this CFT column was proposed, and as a part of the preliminary review process, limiting conditions for the aspect ratio of the ribs were also proposed.