Applications of Finite Element Technology to Reinforced Concrete Explosives Containment Structures

Abstract : Two widely available general purpose computer programs for three-dimensional nonlinear dynamic finite element analysis were applied to three types of reinforced concrete structures of recent interest to Navy explosive safety: a novel cylindrical missile test cell concept, flat slabs with variable shear steel, and a soil-covered roof slab for a new high performance magazine concept. Results from codified single-degree-of-freedom (SDOF) methods for design of explosive safety structures were considered and compared with finite element technology. An overview of these baseline studies is presented. A commercial implicit finite element program was used to analyze the cylindrical missile test cell. Three-dimensional model construction, nonlinear concrete material modeling, and dynamic response were emphasized. Support for embedded reinforcement modeling was found to be very useful in construction of the model so as to retain the inherent anisotropic behavior of the composite structure. Concrete material modeling capability was highly sophisticated, but problematical in application when substantial cracking accumulated in the dynamic response. Sufficient results were nonetheless obtained to demonstrate the value of computational structural dynamics technology in providing detailed understanding of the behavior of complex explosive safety designs, ~ An explicit finite element program was used to analyze the dynamic response of two flat slabs subjected to conventional blast pressure levels.