Local impact effects on concrete target due to missile: An empirical and numerical approach

• Local impact effect of hard missile on reinforced concrete targets has been studied.
• Review of empirical formulation for predicting local response carried out.
• Numerical simulation of experimental test of Kojima (1991) carried out.
• Divergence of FE results with those obtained using emperical formulations.
• Close match of numerical simulation results with experimental data.

Concrete containment walls and internal concrete barrier walls of a Nuclear Power Plant safety related structures are often required to be designed for externally and internally generated missiles. Potential missiles include external extreme wind generated missiles, aircraft crash and internal accident generated missiles such as impact due to turbine blade failure and steel pipe missiles resulting from pipe break. The objective of the present paper is to compare local missile impact effects on reinforced concrete target using available empirical formulations with those obtained using LS-DYNA numerical simulation. The use of numerical simulations for capturing the transient structural response has become increasingly used for structural design against impact loads. They overcome the limits of applicability of the empirical formulae and also provide information on stress and deformation fields, which may be used to improve the resistance of the concrete. Finite element (FE) analyses of an experimental impact problem reported by Kojima (1991) are carried out that are able to capture the missile impact effects; in terms of local and global damage. The continuous surface cap model has been used for modelling concrete behaviour. A range of missile velocity has been considered to simulate local missile impact phenomenon and modes of failure and to capture the concrete response from elastic to plastic fracture. A comparison is then made between the empirical formulations, numerical simulation results, and available experimental results of slab impact tests. While the numerical simulation is able to capture the experimental trend and results, a comparison of penetration depth and scabbing and perforation limits as per different empirical formulation shows substantial divergence.