Enhancement of flexural performance of RC slabs under impact loading using ultra-high-performance fiber-reinforced concrete

This study examined the impact resistance and residual capacity of reinforced concrete (RC) slabs subjected to high velocity bending loads, particularly focusing on the effects of reinforcement ratio and concrete type. Two types of concrete were considered: normal-strength concrete (NSC) and ultra-high-performance fiber-reinforced concrete (UHPFRC). Experimental results demonstrated that NSC exhibited a brittle failure in tension with limited strain capacity, whereas UHPFRC displayed superior ductility. Under static loading, the UHPFRC slab reached a markedly higher peak load than that of the NSC slab. Impact test results indicated that the reinforcement ratio had minimal influence on the peak reaction force, whereas the incorporation of UHPFRC led to a significant increase. Increasing the reinforcement ratio contributed to a reduction in deflection under impact loading, while replacing NSC with UHPFRC resulted in an even more substantial improvement. Despite the higher reaction force, UHPFRC was highly effective in limiting deflection. In addition, UHPFRC slabs demonstrated excellent residual flexural capacity, maintaining their load-carrying ability even after experiencing impact-induced damage. Numerical analyses were carried out to validate the experimental results and reinforce the observed findings. The simulations demonstrated a strong correlation with the experimental data, accurately reproducing the time histories of both impact and reaction forces, as well as the maximum deflections. In addition, the analyses effectively reflected key experimental observations, notably the influence of concrete type and reinforcement ratio on impact behavior, thereby supporting the robustness and reliability of the experimental conclusions.