The main challenge of this project is to determine whether the state-of-the-art hydrocode (MAZ) can accurately predict the blast loads on a simple open structure. The structure being considered is a 30’ × 30’ square slab raised to an elevation of 14’ by four 2’ × 2’ square posts at the corners. A blast calculation was performed to determine the pressure loads on the lower surface of the slab when a small charge of TNT is detonated below its center. The predicted pressure-time histories at selected locations on the lower surface of the slab were given to the experimentalists for gage ranging purposes prior to the tests. The posttest comparison of the measured and predicted pressure-time histories show excellent agreement in the peaks and impulses associated with the first pulse. However, the predicted second pulse arrived much earlier than the measured second pulse. Since the origin of the second pulse is expected to be a result of the collapse of the initial void created by the expansion of the first blast, a posttest calculation is made with a much larger but coarser grid to calculate this late-time collapse. The posttest calculation showed a second pulse that is in agreement with the measured. We conclude that MAZ is able to accurately predict the blast loads; but, the capacity of the current class of desktop machines often forces the analysts to break up physical problems into manageable pieces. Despite the rapid advances in desktop computers, a significant amount of engineering judgment is still required in practice.

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