LATERAL POSTBUCKLING ANALYSIS OF BEAMS

The nonlinear lateral buckling response of perfect stocky beams in the vicinity of the critical bifurcational state is discussed. Attention is focused on the initial post-buckling response. This depends on the nature of the critical branching point which is explored by using a no nlinear (lateral) bending-curvature relationship. It is found that the plane of loading (associated with the major moment of inertia) looses its stability through a stable symmetric bifurcation point. Hence, th e above beams are not sensitive to imperfections, exhibiting post-buck ling strength. However, the post-buckling equilibrium path is quite sh allow, so that the load-carrying capacity of such beams above the crit ical state is rather limited. The analysis is supplemented by illustra tive examples for I-beams for which the effect of various parameters o n the initial postbuckling path is also discussed.