STUDY ON STRUCTURAL PERFORMANCE OF CONCRETE-FILLED OVAL TUBULAR STEEL COLUMNS

This study deals with the structural behavior of concrete-filled oval tubular (CFT) steel columns. The design formulae are proposed approximately on the yield bending moment and full plastic moment of the oval CFT cross section. They are available in the arbitrary loading direction by introducing simple power series of trigonometric function instead of the difficult elliptic integral of the 2nd kind. Experimentally, specimens were tested under reverse-symmetry cyclic loading to investigate the effects of the loading direction of the oval, axial force ratio, and deformation capacity of the CFT columns. The test results verify that these effects depend on the curvatures around the compressive edge of the oval tube sections. Based on the experimentally obtained equivalent diameter - to - thickness ratio (D/t) of elliptic tube, simple evaluation formulae are proposed on the confinement effect and deformation capacity of the oval CFT columns.