In the design of defense structures, concrete slabs are often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, the Taylor-Chen-Kuszmaul (TCK) continuum damage model is further improved and successfully implemented into the dynamic finite element code, LS-DYNA, with erosion algorithm. The numerical predictions of impact and exit craters of concrete slab as well as the residual velocity of projectile using the newly-implemented numerical tool show good agreement with experimental observations. The performance of the modified TCK model is evaluated by comparing with the material Type 78 (Mat _ Soil _ Concrete) and Type 111 (Mat-Johnson-Holmquist-Conerete) available in LS-DYNA. The effect of CRH (caliber-radius-head) ratio of the ogive-nose projectile on the impact crater is also investigated using the new numerical tool. Finally, the maximum penetration depth of steel projectile into a concrete slab is studied and an empirical formula is proposed. (c) 2006 Elsevier Ltd. All rights reserved.