A Parametric Postbuckling Analysis of an Asymmetric Two-Bar Frame

ABSTRACT ABSTRACT The modified potential energy approach of flexurally elastic, axially, and shear undeformable beams is employed to investigate the buckling and (asymmetric) postbuckling behavior of the two-bar frame which was experimentally tested by Roorda in 1965. Following a Koiter-type energy approach, a suitable perturbation formulation is, derived from a hybrid functional which is obtained by adding to the potential energy certain extra terms which account for the energy associated with the internal joint forces acting on the beam. In this way the nonlinear constraints expressing continuity of displacement across the joints are accommodated by introducing joint forces acting as Lagrangian multipliers. The inherent simplicity of the model herein proposed allows a thorough parametric analysis to be performed without undue complications up to and including fourth-order terms. The general trend compares favorably with the experimental results. Previous analytical results limited to a third-order analy...