Compression behaviour of stiffened double skin tubular columns: Influence of stiffener number and sub-panel width

Double-skin tubular columns (DSTCs) represent one of the most advanced lightweight steel-concrete composite designs featuring two concentrically arranged hollow steel tubes, with concrete infill positioned between them. These light weight DSTCs are very efficient at withstanding extremely high axial compressive loads, due to extreme confinement of sandwiched concrete and delayed failure of steel tube. However, the development of early plastic hinges in the form of localized buckling of steel often prevents DSTCs from attaining the full plastic capacity of steel elements, constraining the overall structural performance. Past studies have introduced steel stiffeners to inner tubes, outer tubes, or both, which further improved the axial load-carrying capacity and ductility. However, the data pertaining to the impact of stiffener number, stiffener width, stiffener spacing, with different geometric characteristics and mechanical strength of materials in DSTCs in the literature is very limited. This study aims to develop a detailed dataset for circular outer tube stiffened-DSTCs (SDSTCs) with a wide range of stiffener number, stiffener width, stiffener spacing, with different geometric characteristics and mechanical strength of stiffeners. A verified nonlinear analysis model was developed in the current investigation to study the performance and behaviour of these SDSTCs. This extended numerical analysis identifies and idealizes the critical parameters governing the axial compressive strength, failure mechanisms, and overall behavior of SDSTCs. These findings offer deeper insights into the performance of SDSTCs with a wide range of D o , D i , n s , and w s , contributing to advancing their design and optimizing their structural efficiency in structural applications.