Assessment of empirical formulas for prediction of the effects of projectile impact on concrete structures

The prediction of the response of structures subjected to projectiles impact may often be accomplished by means of empirical or semi-empirical formulas available in the technical literature, which address mainly cases of relevance in engineering practice in terms of the observed failure modes. The paper presents an evaluation of the performance of the equations most widely used in predictions of penetration, scabbing and perforation of concrete and rock structures by comparing the predicted results with experimentally observed response and with the results of detailed numerical analyses employing the truss-like Discrete Element Method (DEM). Numerical DEM predictions were shown to be close to the experimentally determined responses of concrete plates subjected to impact throughout the range of velocities examined and were also consistent with the empirical formulas. In all cases the authors attempted to quantify the uncertainty inherent both in the predictions of empirical formulas and of the numerical analysis.