Concrete Structures: Penetration Depth Estimation

The predictability of the National Defense Research Council (NDRC) equations to estimate penetration depth in concrete structures has been reevaluated using the presently available test results on missiles similar to those expected in a nuclear power plant. This study confirms the industry notion that the NDRC equations overpredict the penetration depth. In a probabilistic formulation like the one routinely used in the nuclear industry, the use of this deterministic penetration depth is overconservative and unrealistic. The NDRC equation is updated statistically using the presently available test results. This statistical NDRC equation significantly improves the predicted penetration depth. However, the form of the NDRC equation may not be ideal. A new relationship is proposed here to estimate the penetration depth by introducing a dimensionless impact factor. The proposed relationship is better than the NDRC or even the statistical NDRC equation. The proposed relationship should be used in the future to estimate the penetration depth for concrete structures.