On the Stability of Frame Members in a Global Buckling

Abstract

In the global buckling of a framed structure, members are examined for their own stabilities. It is shown that, besides the actual member forces exerted, there can be considered a critical axial force of each member determined by its displacement mode in the global buckling. The effective lengths of members are defined for those critical forces. The stability state of each member is qualified by the actual axial force acting on that effective length. The global buckling is explained as an assembly of those stability states of members.

Effective Column Lengths in a Rectangular Rigid Frame

“…At the same time, there has been a controversy on how those lengths be determined accurately in an actual structure. 3)-8), 10) In this study, the attention is focussed on rectangular frames with rigid nodes. In the existing design codes, e. g. 1), 2) the effects of elastic restraint by the neighboring beams are certainly reflected onto the buckling strengths of column members.…”

“…10), the stability states of frame members are quantitatively estimated by the use of their displacement modes and axial forces. The expansions themselves are correct as a stability analysis of discretized structures, and the effective lengths are defined for the individual members.…”