BEARING CAPACITY OF L-SHAPE CFT STUB COLUMNS WITH BINDING BARS SUBJECTED TO ECCENTRIC COMPRESSION LOAD

It is an effective method to improve the mechanical behavior of special-shape concrete-filled steel tubular columns by setting binding bars in the middle position of steel plates which constrain outer convex of the steel plate. A total of 8 L-shape concrete-filled steel tubular (L-CFT) stub columns with binding bars subjected to eccentric compression were tested. The test results demonstrate that the local buckling of the steel plates is delayed and the bearing capacity and ductility of eccentric-loaded specimens are improved by setting the binding bars. The assumption that plane section remains plane is also proved for the specimens. The fiber model was applied to predicting the bearing capacity of the specimens, where the concrete is assumed to follow the constitutive relationship of L-CFT with binding bars. The predicted results agree well with experimental ones. An extensive parameter study is conducted to investigate the effects of steel yield strength, sectional steel ratio, concrete cube strength, constraining factor of binding bars and load angles on N/Nu —M/Mu curves. A simplified method is put forward to predict the bearing capacity under biaxial bending .