System buckling analysis for multi-story frames subjected to nonconservative forces

Abstract

The evaluation of the effective length factor (K-factor) of columns based on the system buckling approach is a convenient tool in the stability design of multi-story frames. This method is superior to other analytical approaches, such as isolated subassembly and story-based approaches, in that inter-column and inter-story interactions are inherently taken into account. In this study, in order to investigate the effect of nonconservative forces on buckling loads and K-factors for the single- and multistory framed structures, the system buckling approach is presented. For this purpose, the finite element model, based on the Hamilton's principle, is formulated for the stability analysis of framed structures subjected to nonconservative forces. In numerical examples, buckling loads and K-factors for single- and multi-story frames subjected to conservative or nonconservative forces are evaluated and compared with those obtained by other researchers. Especially the effect of the stiffness ratio of girder to column on K-factors is investigated for nonconservative systems.