Discrete element modelling of concrete structures under hard impact by ogive-nose steel projectiles

Concrete structures are widely used as shielding barriers to protect sensitive infrastructures. Accidental conditions such as aircraft impacts on nuclear containments lead to a designing demand under extreme loadings. A discrete element method (DEM) model is presented, able to predict damage of concrete structures under severe impacts. The original developments of Cundall and Strack for granular materials were extended in the proposed DEM model for cohesive materials such as concrete by introducing cohesive interactions in addition to contact ones. Spring-like interactions between discrete elements are based on phenomenological models inspired by observations at the macroscopic scale. Constitutive parameters are calibrated thanks to simulations of experiments performed under different states of loading (unconfined quasi-static tests, high confined compression, high strain rates). The DEM approach is validated with the simulation of three hard impact tests where numerical and experimental results are discussed. CEA Gramat performed the experiments on plain concrete targets with a passive confinement given by a steel jacket surrounding the cylindrical specimen and submitted to the impact of ogive-nosed steel projectiles.