Protecting RC Plate Subjected to Combined Effect of Blast and Fragments with ECC

To improve the resistance of reinforced concrete (RC) plates against combined blast and fragment loading, the effectiveness of engineered cementitious composite (ECC) protective layers was investigated. Existing studies have mainly focused on single loading conditions, while the coupled effects and the influence of key ECC design parameters remain insufficiently understood. In this study, validated numerical models were developed to examine the effects of ECC thickness, compressive strength, and protective configuration on the structural response. The results show that ECC protection significantly mitigated damage and deformation, identifying thickness as the dominant factor. As the ECC thickness increased, the cratering area decreased from approximately 650,000 mm2 to nearly zero, and the central displacement was reduced from 32.2 mm to 18.7 mm (≈42% reduction). In contrast, increasing compressive strength from C30 to C70 resulted in only a limited reduction in displacement (26.6 mm to 23.9 mm). Regarding configuration, double-sided protection further reduced displacement to 19.7 mm (≈39% reduction) and effectively suppressed damage on both surfaces. Overall, the protective performance of ECC layers is governed primarily by thickness and configuration rather than compressive strength. These findings provide quantitative guidance for the design of ECC-strengthened RC structures under combined blast and fragment loading.