In AIJ (Architectural Institute of Japan) design formula for slender steel-concrete composite columns, modified method of the superposed strength of a column section is adopted by considering the effect of additional bending moment (Pб moment). We have proposed an equation for evaluating the strength of slender concrete columns, and using this we showed that the strengths of concrete filled steel tubular (CFT) columns and RC columns are well predicted. In this paper, with respect to the strength of SRC columns with various steel sections, end moment (M_u) -axial force (N_u) interaction relations are calculated by assuming a sine curve deflected shape of the beam-column. As the analytical parameters, buckling length-section depth ratio, tensile reinforcement ratio and strength of concrete are selected. On the basis of the analytical results, the superposed strength is examined, and proposed.
