Behavior of stiffened and multi-cell L-shaped CFST columns under eccentric compression

Abstract

The mechanical behavior of the traditional special-shaped concrete-filled steel tubular (CFST) columns can be improved by employing longitudinal stiffeners or using multi-cell cross-section. In practical application, the stiffened and multi-cell L-shaped CFSTs are often subjected to bi-directional loading. However, there are only few research studies on their performance as loaded eccentrically with different orientations of the loading and there is no relevant design guideline. This paper reports tests on 16 L-shaped CFST columns (nine stiffened, six multi-cell specimens and one reference specimen) loaded in eccentric compression. The main variables were the angle indicating the orientation of the load action line (0°, 45°, 135°, 180° and 225°), load eccentricity ratio (0, 0.25 and 0.5) and slenderness ratio (31.5 and 41.9). Finite element models for the eccentrically loaded stiffened and multi-cell L-shaped CFST columns were developed. Based on the parametric analysis, practical design methods were proposed for predicting the bearing capacity based on the stability loss and the axial force vs. bending moment interaction diagrams for the members considering the influence of the load orientation at the end face of the column.