Second- order analysis in braced slender columns was investigated in this study. The present study
is concerned with two main points. The first point is focusing on how to compute the additional
moments in slender columns according to accredited equations in different codes as well as the basics
and the assumptions of these equations. In the second point, approximate equation was suggested to
compute the additional moments in slender columns. This equation was proved in elastic analysis and
for the cases of single curvature in slender columns. The equation was proved by considering the
column supported on two pin supports with rotational springs. The rotational springs represent the
connected beams with the columns. The suggested equation gave matching values of the induced
additional moments of slender columns compared with finite element results in elastic analysis.