On the mechanics of local-distortional interaction in thin-walled lipped channel beams

Abstract

This paper investigates the elastic post-buckling behavior of simply supported thin-walled lipped channel beams undergoing local-distortional (L-D) interaction. The beams are uniformly bent about the major-axis and experience flange - triggered local buckling (most common situation in practice). Three beams are analyzed, each exhibiting a different type of L-D interaction, namely (i) “true L – D-interaction” (close local and distortional critical buckling moments), (ii1) “secondary local-bifurcation interaction” and (ii2 ) “secondary distortional - bifurcation interaction”(critical distortional/local buckling moments and high enough yield stresses) .The results presented and discussed are obtained through geometrically non–linear Generalized Beam Theory (GBT) analyses and provide the evolution, along given equilibrium paths, of the beam deformed configuration (expressed in GBT modal form) and relevant displacement profiles, making it possible to acquire in-depth knowledge on the beam L-D interaction mechanics. Particular attention is devoted to interpreting the quantitative and qualitative differences exhibited by the beam post-buckling behaviors associated with the three aforementioned L-D interaction type.