Projectile Impact on Plain and Reinforced Concrete Slabs

Reinforced concrete is a material frequently used in protective structures and infrastructure exposed to extreme loading. In this study, the ballistic perforation resistance of 100 mm thick plain and reinforced concrete slabs impacted by 20 mm ogive-nose steel projectiles was investigated both experimentally and numerically. Two different reinforcement configurations were used to investigate the effect of rebar diameter and spacing. Concrete with nominal unconfined compressive strength of 75 MPa was used to cast material test specimens and slabs. Ballistic impact tests were performed in a compressed gas gun facility. The mechanical properties of the concrete were found using standardised tests and two-dimensional digital image correlation, and the constitutive relation was described by a modified version of the Holmquist-Johnson-Cook model. Finite element models in LS-DYNA reproduced the projectile residual velocity in good agreement with the experimental results. The primary objective of the study was thus to validate a rather simple constitutive relation intended for large scale numerical simulations of concrete structures exposed to ballistic impact loading, while a secondary objective was to investigate the effect of reinforcement on the ballistic perforation resistance of concrete slabs both experimentally and numerically since the literature is somewhat inconsistent on this matter.