Post-Buckling of Axially Compressed Plates

Aluminum square tubular sections subjected to axial compression generally exhibit a significant reserve of strength above the critical stress levels associated with plate buckling. Load-transverse deflection curves averaged over the four faces of each of six specimens with different slenderness ratios B (width to thickness) validates the nature of behavior predicted in an earlier paper. Membrane action for slender plates (60.8≤B≤106) dominates behavior in the vicinity of the critical load so as to elevate the rate of resistance to load with deflection. Elastic-plastic behavior with its attendant deterioration of stiffness begins to predominate prior to the attainment of the ultimate load resulting in a plastic mechanism at large displacements. Stiff plates (30.8≤B≤45.5) reach ultimate load without the characteristic membrane response and immediately tend to follow a mechanism unloading line.