Initiation of plastic folding mechanism in crushed box columns

Abstract

A simple computational model of a thin-walled prismatic column is developed, which describes a transition from the postbuckling to the postfailure and crushing deformation phase. Energy methods are used to analyze the elastic post-buckling response of the column. Ultimate strength is calculated, using the first yield criterion. Limit analysis methods, properly generalized to large displacement and rotation problems, are employed in the postfailure range. The new model explains, with some realism, the process of strain localization and the formation of a plastic folding mechanism in the column. It also leads to a prediction of the entire load-deformation characteristics up to the internal touching and stiffening.