Lateral-Torsional Buckling of Post-Local Buckled Fibrous Composite Beams

Abstract

Interactive buckling of fibrous composite I-section beams is discussed in this paper. As a result of a linear combination of local and lateral-torsional buckling modes, which may arise when the critical loads of these two types of buckling are nearly the same, a large degradation in the failure load capacity may occur. In this study, the flanges are considered as beam elements when the member bends laterally under the prebuckling stress distribution and as plate elements for normal bending and twisting; the web is analyzed as a plate element. Within the framework of the Rayleigh-Ritz method, a displacement function formulation is employed using compatibility conditions at the junction between flange and web for unifying the analytical treatment and reducing the problem size. The effect of the combined in-plane stresses, produced by longitudinally varying stresses due to the applied transverse loads, on the critical load also is discussed.