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Modeling and Simulation of HD 1.3 Thermal Initiation Tests
on a Small Reinforced Concrete Storage Structure
Ming Liu, Michael Oesterle, and Robert Conway
Naval Facilities Engineering and Expeditionary Warfare Center
1100 23rd
Ave., Port Hueneme,
CA
93043-4370
Josephine Covino, Department of Defense Explosives Safety Board
Suite 16E12 4800 Mark Center Drive Alexandria, VA, USA
Key words: HD 1.3 Thermal Initiation Test, Choked Flow, Simulation, Kasun Structure
Abstract
This paper presents the efforts on modeling and simulation of HD 1.3 thermal initiation tests on a small reinforced
concrete (RC) storage structure (called Kasun structure) with the finite element analysis software code LS-DYNA.
Based on the detailed studies on mesh size, material model, erosion criterion, boundary condition, and modeling of
lap splice, a full-scale half-symmetry numerical model was created to determine the worst-case loading scenario
from the prescribed pressure load-time histories. In general, HD 1.3 explosive materials generate mass fire with little
or no fragmentation. However, under a confined storage condition, HD 1.3 explosive materials can also generate a
scenario that results in a pressure vessel like rupture of the RC structure. This scenario is called the “choked flow”
and is heavily related to the flow rates. Thus, the prescribed pressure load-time histories in this study cover the
choked flow with initial flow rate, choked flow with double flow rate, half-choked flow with initial flow rate, half-
choked flow with double flow rate, and the two other general loading curves called the P1 and P6 loading curves.
The simulation results demonstrated that the numerical model is capable of predicting failure modes observed in the
live field test. These failure modes include the initial cracking at the corners of the walls, the heavy damage of the
floor slab, the rupture of the roof, and the failure of the steel door. The simulation results also showed that the
connection details between the steel doorframe and the concrete walls is an important factor that significantly affects
the failure modes in both computer simulation and field tests. Based on the failure time and corresponding blast
pressure at the time of the break-up of the Kasun structure, the worst-case loading scenario is determined to be the
half-choked loading with double flow rate, followed by the half-choked loading with initial flow rate. The choked
loading with double flow rate and P1 loading curve also cause the break-up of Kasun structure, but the choked
loading with initial flow rate and P6 loading curve did not cause any break-up at all. Recommendations for future
studies have been made to improve qualities of computer simulations, such as sensitivity studies on the numerical
erosion mechanism that represents the physical fracture mechanism as well as the coupled simulations that can
consider the fluid-structure interaction (FSI) between the blast waves and the structure. Probabilistic approaches
that can deal with the random process of heterogeneous material break-up are also recommended for future studies.
