Predictions of permanent deformation of impulsively loaded simply supported square tube steel beams

Abstract The paper describes experimental and theoretical work on model scale simply supported hollow steel beams of square tube section. In the experimental work, the beams were loaded impulsively by detonating a strip of sheet explosive along the top surface, using a fairly thick layer of styrofoam to spread the effect of the explosive strip. Impulses were measured by means of a ballistic pendulum. Local deformations of the order of the cross-section dimensions took place; however, these were uniform along the beam, indicating that the local and global beam deformations were sequential. In the analysis it is assumed that the local and global deflections are uncoupled. The local deformation is predicted approximately by treating the cross-section as a rigid-viscous portal frame, and the global deformation by treating the simply supported beam by an approximate elastic-plastic approach. Given the simplicity of the analysis, acceptable estimates of the deformation are obtained.