REAR FACE DAMAGE OF NORMAL AND HIGH-STRENGTH CONCRETE ELEMENTS CAUSEDBY HARD PROJECTILE IMPACT

Rear face damage assessment od scabbed, punched, or perforated concret e barriers due to hard projectile impact was evaluated according to th e spalling volume and size by using existing, classical and more moder n penetration formulas. The damage-level calculations are done for var ious velocity ranges, below and above the perforation limit. An experi mental work included a comparison between the response of normal stren gth concrete (NSC) and high-strength concrete (HSC) barriers to hard p rojectile impact. The experiments were done with a gas gun that accele rated 165 fi (including the saber), hard steel projectiles, whose impa ct velocities ranged between 100 and 250 m/sec, and were measured by a n electro-optical system. Craters at the rear-face of the plate specim ens were examined and showed that the NSC and HSC volumes were similar at similar velocity levels (i.e., relative to the perforation velocit y). The NSC experimental results showed an increased damage level at v elocities that were near or less than the perforation limit velocity. This trend is similar that of a theoretical model prediction.