Experimental and numerical investigation of strengthening strategies for reinforced concrete structures under internal blast loading

This study presents an experimental and numerical investigation of a confined reinforced concrete structure subjected to an internal blast from a 6 kg Comp-B charge, focusing on strengthening strategies using haunch reinforcement. Experimentally obtained pressure–time data were expanded through CFD simulations and used as input for FEA. The numerical model successfully captured cracking and separations observed at slab–shear wall joints. To mitigate damage, three haunch configurations were evaluated. In the Type 1 (30 × 30 cm) and Type 2 (60 × 60 cm) models, bottom-surface slab cracking was prevented, slab displacements and joint separations were reduced, and support rotation angles decreased to 13.42° and 12.74°, respectively. The Type 3 model, incorporating additional longitudinal reinforcement and extended development lengths, demonstrated the best performance, reducing the support rotation angle to 4.95°, significantly decreasing displacements, and delaying structural failure. The findings confirm that haunch strengthening significantly enhances blast resistance, particularly through improved reinforcement detailing in critical joint regions.