Experiments were performed wherein thin-walled square aluminium tubes were subjected to lateral compression by short width indenters in two different modes, under both quasi-static and impact loading. Tubes employed were empty as well as filled with polyurethane foam and kail wood. The deformation histories of the collapsing tubes were studied and their collapse loads as well as post collapse load-compression curves are presented. Based on the mechanism of deformation observed experimentally and considering the material to be rigid-plastic, collapse load values and post collapse load-compression curves were computed. The results thus obtained compared with experimental values very well.