Slenderness of Columns in Braced Frames

Moment‐magnification factors for columns in braced frames are dependent upon column slenderness and the flexural stiffness of restraining beams. A column bent in single curvature has a flexural stiffness that can be as little as one‐third that of the same column bent in reverse curvature. Column slenderness ratios $(L/R)$ above which reverse curvature moments must be magnified are significantly higher than those for which single‐curvature moments would require magnification. This paper shows that when loading conditions are considered together with framing restraints, magnified moments from the single‐curvature condition rarely generate moment values as high as moments unmagnified from the reverse‐curvature loading condition. Thus, without need for moment magnification, column slenderness ratios can be significantly higher than the limit ratios traditionally derived for single‐curvature bending conditions of columns.