Presentation of Critical Buckling Load Correction Factor of AISC Code on L-Shaped Composite Columns by Numerical and Experimental Analysis

Abstract

Concrete-filled steel tubular (CFT) columns have been widely used as structural members in buildings and bridges in recent years, because of their properties, such as high strength and stiffness, good ductility, and convenience for construction. In CFT columns, the bearing capacity of columns is inversely related to buckling, therefore, buckling is of particular importance at these sections, the AISC Code uses effective bending rigidity (EIeffective) to calculate the critical buckling load in concrete filled steel columns, to apply the effect of reducing concrete confinement, the AISC code provides a maximum value of 0.9 of the reduced concrete confinement coefficient for the equation. Effective bending rigidity (EIeffective), this relationship is provided in AISC code for circular and square sections, therefore, the effect of the column shape geometry on the core concrete confinement is very influential and changes the effective bending rigidity (EIeffective) of the section. The AISC code does not provide a coefficient to consider the type of cross-sectional geometry in CFT columns, therefore, in this study, three groups experimental, numerical (FEM) and theoretical were used to provide critical buckling load correction, finally, it was concluded that the critical buckling load for the cross-section (L) shape due to the lower confinement of the concrete core is 20.07% lower than the AISC code equation, also with a 67% increase in slenderness ratio, the critical buckling load decreased by 14.52%.