Evaluation of parameters which influence circular slender CFDST columns subjected to eccentric loading

Abstract

Significant research was devoted to determine the effect that various parameters have on the ultimate load of circular slender Concrete Filled Double Skin Tubular (CFDST) columns subjected to concentric loading. However, the same research attention has not been devoted to circular/square/rectangular CFDST columns subjected to eccentric loading. This has limited the development of codified requirements for CFDST columns, since design codes require column loads to be applied eccentrically to accommodate construction tolerances. To contribute to the body of knowledge, a Finite Element (FE) analysis investigation was performed to determine the effect that various parameters have on the ultimate load of circular slender CFDST columns subjected to eccentric loading. This investigation was conducted using 4 different column specimens to obtain a holistic overview of the effect of the parameters on the column’s response. The parameters that were investigated include; concrete and steel strengths, inner and outer tube thicknesses, column curvature, load eccentricity and column support fixities. The investigation revealed that a change in the concrete and steel strength has a moderate effect on the ultimate load of slender circular CFDST columns subjected to eccentric loading. A change in the inner and outer tube thicknesses as well as an increase in the load eccentricity has a significant effect on the ultimate load. The longitudinal curvature of the column has the least effect on the ultimate load, while the column’s support conditions have the greatest effect on the ultimate load. These findings are similar to what was observed for concentric loading.