Response of Concrete Elements Subjected to Impact by Fragments with Varying Aspect Ratios

Concrete specimens of varying compressive strengths were subjected to impact from fragments with relatively common width-to-thickness, or aspect, ratios. The influence of material characteristics on penetration and perforation response and the ability of existing penetration depth prediction methodologies to forecast protective structural member performance when impacted by these fragments were evaluated. The structural element response was assessed using a cylindrical target specimen designed with a circumferential steel ring to provide radial confinement. The general relationships between concrete compressive strength and impact response, mass loss, and the benefits of fiber reinforcement in structural element protective performance were found to be similar regardless of fragment aspect ratio. Compressive strength was found to have a greater effect on impact performance, and penetration depth was found to be of greater concern as the fragment aspect ratio decreased. Some existing penetration methodologies were found to be fairly accurate when predicting impact response from lower-aspect-ratio fragments; this was not the case for high-aspect-ratio fragment impacts on the same concrete materials.