Shock Absorbing Structural Elements

The Naval Facilities Engineering Service Center (NFESC) is developing a new ordnance storage magazine that will reduce encumbered land and improve operational efficiency. Energy absorbing walls using lightweight concrete are being developed to prevent sympathetic detonation between cased munitions stored in adjacent cells. Design loads, wall response, and wall effectiveness are predicted and compared to test results from one-third scale development tests and full scale demonstration and certification tests. Specially designed lightweight concretes (or chemically bonded ceramics, CBC's) with high porosities in excess of 50% were used in the development program. The most efficient (cost and performance) barrier wall design utilizes a composite wall consisting of an exterior reinforced concrete cover and a heavy granular fill material. The CBC which makes up the cover has a strength of 2500 psi, a unit weight of 65 pef, and a porosity over 50%. This CBC cover mitigates initial shock on impact with acceptors while the heavy granular fill reduces wall velocity (and kinetic energy), disperses momentum, and stops fragments. The exterior magazine walls, also constructed with lightweight concrete, reduce shock loads on impact by acceptor munitions.