This two-part paper presents the results of experimental and numerical work on the crushing characteristics of square tubes, with blast-induced imperfections, subjected to axial load. In Part I, the experimental studies are presented. The approach in the studies involves creating imperfections on opposite sides at midlength of a square tube by means of localized blast loads to create three types of imperfections: nontouching domes, rebound domes, and capped domes. These imperfections change the geometry and the material properties in the midsection of the tubes and hence affect the crushing characteristics. While the blast-induced imperfections enhance the energy absorption characteristics of the tubes they also affect the lobe formation process. In Part II, the finite element package ABAQUS/EXPLICIT v6.5–6 is used to construct a symmetry model by means of shell and continuum elements to simulate the tube response to the localized blast loads followed by dynamic axial loading in the form of a rigid mass impacting at a specified initial velocity. The hydrodynamic code AUTODYN is used to characterize the localized blast pressure time and spatial history. The predictions show satisfactory correlation with experiments for both crushed shapes and crushed distance.