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Structural Response
of an
Earth Covered Magazine
to a
Simulated Blast Loading
Joseph Hamilton
[1]
, Mark Weaver
[1]
, Joseph Abraham
[1]
[1] Karagozian and Case, Inc. 700 N. Brand Ave, Suite 700, Glendale, CA 91203-3215
Keywords: earth covered magazine, airblast load, LS-DYNA
Abstract
A series of high-fidelity physics-based simulations were performed to assess the performance of an
earth covered magazine (ECM) to an idealized airblast load applied to the soil above the roof. A
representative ECM model was generated based on a survey of existing ECM drawing sets. The
simulated structure consisted of reinforced concrete walls, columns with capitals and drop panels,
and a roof slab. The concrete and soil were modeled using solid Lagrangian elements and the K&C
concrete material model. Due to uncertainty regarding existing material strengths (i.e., due to
variation in the surveyed drawing sets, age of these structures, and the limited amount of testing
available for in-situ materials), unconfined concrete compressive strength and reinforcing steel
yield strength were varied across the simulations performed.
This work records the assumptions inherent in the analytical model and the results obtained from
these simulations. In particular, the ultimate failure modes observed and how failure modes changed
as material properties were varied is presented. Based on the results of these simulations,
recommendations concerning improvements to modeling ECMs are offered.
Introduction
Magazines are used for storing ammunition and explosive materials and they are classified as either
Aboveground Magazines (AGM) or Earth Covered Magazines (ECM). As described in the Unified Facilities
Criteria for Ammunition and Explosives Storage Magazines, an ECM is not designed to resist the effect of its own
exploding contents. Rather the intended purpose of an ECM is to mitigate a sympathetic detonation from an adjacent
ECM (U.S. Army Corps of Engineers 2015).
This paper provides a review of an effort to better understand the response of a representative ECM to a
roof-applied airblast load and the model’s sensitivity to material parameters such as concrete and reinforcing steel
strength properties. The structure was modeled with LS-DYNA using Lagrangian elements and segment loading of
the soil to simulate an airblast loading condition. To expedite run time, two versions of the ECM model were
created. The first was a partial-strip model that was used to assess the sensitivity of the ECM’s response to different
loads and material strength properties. The second was a half-symmetry model that incorporated more realistic
boundary conditions to better assess the ultimate failure mechanism of an ECM exposed to roof-applied airblast
loads. The modeling setup and results from both the partial-strip and half-symmetry models is covered in this paper.
Model Setup
Three sets of drawings of ECMs from different time periods were reviewed to determine parameters for
various properties of the building structure, such as concrete strength; reinforcing steel strength and layout; soil, wall
and slab thicknesses; and column dimensions. In some cases, such as with wall thickness and reinforcing steel
