High strength fiber reinforced beams under impact load

Abstract

High strength fiber reinforced concrete beams with different contents of steel hooked end fibers (without fibers, with 40 and 80 kg/m3 ) were tested under impact loads using a Drop - Weight Impact device with different projectile impact velocities. Numerical modeling was additionally carried out with Karagozian and Case constitutive model for concrete that was calibrated to include the effect of the fibers in the post-peak response of fiber reinforced concrete. Before matrix cracking the behavior was almost independent on fiber content and the first crack appeared for the same impact velocity corresponding to a maximum impact load that was approximately 10 times the static cracking load. For the same impact velocity, maximum impact load was slightly higher for beams with higher fiber content that presented evident smaller cracks and deflections. The benefit of doubling the fiber content from 40 to 80kg/m3 on the dynamic structural performance was similar to that obtained in the static flexure response, while, at material level, it was lower.