SIMPLIFIED DESIGN FORMULA OF SLENDER CONCRETE FILLED STEEL TUBULAR BEAM-COLUMNS

Abstract

In AIJ (Architectural Institute of Japan) design formula for slender composite columns, modified method of the superposed strength of a column section is adopted by considering the effect of additional bending moment (Pδ moment). In a previous paper, with respect to the ultimate strength of concrete filled steel tubular columns, we proposed the end moment (_cM_u)-axial force (_cM_u) interaction relations of concrete columns on the basis of an analytical results. The equation for the _cM_u-_cN_u relations, however, is considerably complicated. In this paper we proposed more simple equation and show that maximum strengths are well predicted by using the proposed _cM_u-_cN_u relations.