Structural behavior of concrete filled cold formed steel tubular columns under axial compression

Volume Title: ICASGE2025

Paper ID : 1034-ICASGE-FULL

The concrete-filled steel tubular (CFST) members have many structural advantages that led to widespread use of them in structural engineering. Steel and concrete are used in concrete-filled steel tube members in such a way that their natural and most notable properties are used. However, effective measures should be taken to enhance the bond behavior, prevent premature buckling, and improve the confinement effect of the steel tube on the concrete core, especially in square and rectangular columns. As a result, new shapes of longitudinal ribs were developed to improve the performance of square and rectangular CFSTs under concentric and eccentric compression. Despite significant improvements in delaying the local buckling of steel tubes after incorporating rib stiffeners, local buckling or cracks along the welded corners were previously noted in some testing specimens. To overcome this issue, stiffened CFST columns with round corners are used. This paper suggests a new stiffening system. The system relies on using cold-formed steel sections as a replacement for the conventional stiffeners. These columns require only 4 weld lines to be fabricated. Using this type of stiffening scheme can improve the performance of CFSTs by increasing the axial load and the ductility, achieving better confinement to the concrete core, and reducing the amount of welding required compared to the conventional CFSTs with longitudinal plate stiffeners. Moreover, no cracks of welds were observed in these columns.

Composite columns; Concrete filled tubes; Stiffened tubes; stiffeners; core concrete; Finite element analysis; Axial load; confinement

Structural Analysis (STA)