Seismic performance of square concrete-filled steel tubular columns with diagonal binding ribs

The structural performance of square concrete-filled steel tubular (SCFST) columns can be improved by stiffening the tube. Stiffening delays local buckling and can improve composite action while also facilitates the use of thinner and higher-strength materials. A particularly efficient form of stiffened SCFST column using diagonal binding ribs was proposed recently. Initial studies on the axial behavior of these diagonal ribs stiffened SCFST columns have shown excellent performance. However, further investigation is necessary to better understand their seismic performance under combined loading. In this work, four diagonal ribs stiffened SCFST columns were tested to failure under combined constant axial compression and cyclic lateral load. The main parameters in this study were the presence of holes in the diagonal rib, the width-to-thickness ratio of the steel tube, and the level of axial loading. Detailed analysis demonstrated that the effect of holes was slight, while the width-tothickness ratio and axial load ratio affected the cyclic behavior significantly. Furthermore, based on the verified ABAQUS model, the use of the plastic stress distribution method for computing the interaction strength of short diagonal ribs stiffened SCFST columns was validated among a range of parameters. These parameters are the hole diameter, axial load ratio, material strength and width-to-thickness ratio, including for columns that would be classified as susceptible to local buckling by current design standards. These results provide new knowledge on the behavior of diagonal ribs stiffened SCFST columns and will support the use of this efficient form of composite construction.