Mathematical model of analyzing P–δ effect in braced columns

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 by mathematical model to compute the additional moments in slender column. 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. The suggested equation in this paper is as a preamble for the modified equation in near future. The stiffness reduction in the column and the rotational springs due to the cracking and yielding will be taken into account in the modified equation. Then, the results will be compared with accredited equations in different codes.