Abstract
A new stability design method for frames is presented. Contrary to the effective buckling length concept, the proposed method is based on the elastic second-order analysis. In this method, the introduction of equivalent initial deflections corresponding to the imperfections is of utmost importance. Therefore, a new equivalent deflection formula using curvature is suggested. Moreover, a methodology is proposed to explain the systematic application of this formula to a frame with stepped cross sections. The validity of the metod is demonstrated by some examples.