Despite extensive research on blast-resistant concrete structures, a clear scientific deficiency remains in the quantitative understanding of how fiber-reinforced concrete slabs behave under blast loading, particularly when experimental and numerical investigations are not conducted together under identical loading conditions. Existing studies often focus on either conventional reinforced concrete or isolated material systems, providing limited validation of comparative blast performance across different fiber-reinforced concretes. This study addresses this gap by investigating the blast resistance performance of four types of reinforced concrete slabs: normal concrete (NC), ultra-high-performance fiber-reinforced concrete (UHPFRC), organic fiber-reinforced high-performance concrete (O-HPC), and basalt FRP-sheet-strengthened slurry-infiltrated fiber concrete (F-SIFCON), using full-scale blast experiments and validated numerical simulations conducted with ANSYS Explicit Dynamics. Blast tests were performed to obtain time histories of reflected pressure, displacement, acceleration, reaction force, and internal energy. The influence of different fiber systems and FRP strengthening on dynamic response and failure mechanisms was systematically analyzed. The numerical models showed good agreement with experimental measurements, confirming their reliability. The results indicate that the normal concrete slab exhibited brittle failure and poor blast resistance, whereas the F-SIFCON slab demonstrated the best overall performance. Compared with the normal concrete slab, the F-SIFCON slab achieved approximately a 47% reduction in maximum displacement, a 56% increase in peak reaction force, and the highest internal energy absorption of 236 kJ. The UHPFRC and O-HPC slabs also showed improved blast resistance, although with different post-peak response characteristics. These findings demonstrate that hybrid fiber reinforcement combined with FRP strengthening can significantly enhance the blast resistance of concrete slabs and that coupled experimental–numerical approaches provide a robust framework for evaluating structural performance under extreme dynamic loading.

This research focuses on improving flood management of the Malwathu Oya River in Anuradhapura Historical City, Sri Lanka, by designing an efficient gate system for the weir of Halpan Ela in the Malwathu Oya River. Frequent flooding threatens agriculture, infrastructure, and public safety in this region. This research aims to enhance water level control in the upper reach of Halpan Ela Anicut by evaluating rainfall patterns, tank spillway efficiency, and gate operation challenges. Historical data on rainfall and tank spillage were analyzed. Flow simulations revealed significant pressure differences, with the existing gate structure showing an upstream pressure of 114,492.5 Pa at a maximum flow of 1740 m³/s, compared to 105,406 Pa for the new flap gate system at the same flow rate. This represents a pressure difference of 9 kPa, equivalent to a 0.9 m water head. Despite the system’s estimated cost of USD 0.1 million, the potential reduction in river flood damage, which currently exceeds USD 0.2 million annually, demonstrates its value. This research emphasizes the effectiveness of the flap gate system in reducing flood risks in Anuradhapura City compared to the existing gate type, though it is only a part of a broader flood mitigation strategy.