Strength Predictions of Plates in Uniaxial Compression

The prediction of the ultimate load for rectangular plates is obtained from the intersection of an elastic postbuckling loading path and a rigid-plastic unloading path. The former expresses post-buckling stability and uniqueness, affected by membrane forces and imperfections at large transverse displacements; the latter, insensitive to imperfections, illustrates the reduction in plastic limit load carrying capacity with changes in geometry which occur in a plastic mechanism at large displacements. The ultimate load predicted by this method is shown to bound the true ultimate load of the plate obtainable by an incremental analysis; the resulting solution, while approximate only and applicable to a range of moderately thick plates, is considerably less cumbersome to obtain and estimates the capacity of the plate reasonably well.