Discrete Element Modeling and Analysis of Structural Collapse/Survivability of a Building Subjected to Improvised Explosive Device (IED) Attack

Within the present work, the problem of structural integrity (including potential collapse/survivability) of a model building when subjected to a blast attack by a close-proximity vehicle-borne improvised explosive device (VBIED) is investigated using advanced transient, non-linear dynamics, discrete-element modeling (DEM) and simulation computational methods and tools. Since the DEM approach is highly sensitive to the details of the constitutive-material (and contact-interaction) models, a significant portion of the work is devoted to explaining the formulation and the physical basis for the material models used. In particular, since concrete is the key material used in the construction of a building, a critical assessment is provided of the DEM concrete material model employed. To quantify blast-survivability of the building and, in particular, its key structural components, the concept of the so-called design basis threat, DBT (as quantified by the TNT-equivalent charge mass and the associated VBIED standoff distance) is utilized. To help quantify DBT, a parametric study is carried out involving the following design parameters: (a) TNT-equivalent charge mass; (b) VBIED standoff distance; and (c) the degree of concrete reinforcement with steel. The results obtained in the present work also revealed (in a qualitative fashion) the role that the phenomena such as the interaction of the VBIED-induced soil-borne shock waves with the building underground support structure as well as the interaction of the vehicle fragments and the detonation products with the structural elements of the building play in causing damage (and potential collapse) of the building.