This research examines the physics behind blast waves and their interaction with structures. A computer program, VecTor-Blast, is developed based on the blast wave characteristics of TNT. Energy methods are used to scale TNT properties to other explosives. VecTor-Blast calculates the pressure-time history at specified points on a 3-dimensional cuboid structure.It has been recommended that future expansion of VecTor-Blast include an improvement in the calculations involved in diffraction and that an experimental program be developed to produce more data.The performance of the numerical tool was verified with experimental data. Verification showed that VecTor-Blast is capable of accurately calculating pressure-time histories on the front and rear faces of the structure. Performance on the sides of the structure was shown to be highly conservative due to an over-simplification of diffractive effects. Complex wave phenomena such as Mach stem formation could not be adequately tested due to limitations in available data.