Finite element analysis of experimentally tested concrete slabs subjected to airblast

Abstract

Since the last century, concrete has been used to protect structures against intentional or accidental detonation of explosives. Recently, as concerns about terrorist activities and accidents in plants using explosives increase worldwide, the study of the behaviour of this type of material and any civil or military structure under the influence of explosions has increased. Among the lethal effects of explosive devices, which cause greater loads in structural elements is the airblast effect. For this reason, this paper presents a series of airblast finite element (FEM) simulations developed in Abaqus/Explicit®. To validate the computational method, such simulations are geometrically and structurally kept similar to full-scale tests conducted in a blast test area of the Science and Technology Aerospace Department (Brazilian Air Force). Both simulations and tests consisted of seven reinforced concrete slabs with compressive strengths of about 40 to 60 MPa, variable steel reinforcement areas, slab dimensions measuring 1×1 m, and subjected to 2.7 kg of non-confined plastic bonded explosive. The results demonstrated that FEM simulations can predict the rupture of the tested slabs and how the effect occurs, showing a valid method to investigating the response of RC slabs when compared to expensive field tests. Differences in displacements were observed between the results of FEM simulations and blast field tests, mainly caused by the sensitivity of the case studied, limits of computational capacity, and intrinsic variations in the materials and sensors used in the field tests. However, these differences showed an order of magnitude compatible with the safety coefficients used with RC, demonstrating that the method can be used for the design of RC slabs under the effect of airblast.