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Ultrashort steel fibers with small diameters are often used as reinforcements in concrete. Such fibers are cheap, easily dispersed, and do not unduly reduce the workability of concrete. In this study, cylindrical specimens are fabricated with three different volume fractions of 0.0, 1.5, and 3.0% ultrashort steel fibers (13.0 mm long and 0.2 mm in diameter). Then these concrete specimens are tested under repeated impacts in split Hopkinson pressure bar device. The effects of loading rate, fiber volume fraction, and impact times on the dynamic responses of concrete are respectively investigated. These experimental results show that addition of a small amount of steel fibers can significantly improve the impact resistance of concrete. In the fibrous concrete, the effect of strain‐rate hardening prevails against that of damage softening in the initial impact. Besides, the failure modes of plain and fibrous concretes are noticeably different.

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