EXPERIMENTAL RESEARCH ON COMPOSITE L-SHAPED CONCRETE-FILLED STEEL TUBE SHORT COLUMNS

In order to research and improve the axial bearing capacity of L-shaped concrete-filled steel tube columns, considering the confinement indexes, three composite L-shaped concrete-filled steel tube short columns and nine composite L-shaped concrete-filled steel tube with steel-reinforced short columns were designed. The failure modes of specimens, the load-deformation curves, ultimate bearing capacity and the influences of steel-reinforced and confinement indexes on the axial compression mechanical properties of the short columns, are analyzed and tested. Based on the conclusion of domestic and abroad codes and the regression analysis of the experimental data, the formula for the compression bearing capacity of composite L-shaped concrete-filled steel tube columns was deduced. The test results indicate that the failure mode of composite L-shaped concrete-filled steel tube column is the local buckling failure mode or shear failure mode. The shear failure can be put-off and the axial bearing capacity can be increased effectively because of the existence of steel-reinforced. The ultimate bearing capacity and ductility of the specimen can be increased with the rise of the confinement index. The calculated results are in great agreement with the experiment results, and the formula can be valuable to the engineering design.