Effect of high-strength rebar and ultra-high-performance concrete on blast resistance of slabs under contact explosion loads

Abstract

This study examines the effects of 630 MPa rebar (T63) on the blast resistance of reinforced concrete (RC) structures designed for civil air defense. Five RC slabs were prepared with varying reinforcement ratios, rebar strengths, and concrete grades. Conducted under various blast load equivalents, contact explosion tests assessed the influence of T63 rebar and ultra-high-performance concrete (UHPC) on macroscopic damage, damage modes, and the dynamic stress-strain response of the slabs. Key observations included crack development, and measurements of crater area, diameter, and depth on both the front and rear blast surfaces, as well as acceleration and strain responses. The results showed that RC slabs reinforced with T63 rebars exhibited reduced damage and lower peak acceleration responses compared to those reinforced with HRB400 rebars under the same blast load equivalent, indicating superior blast resistance. As the blast load increased, cratering on the front blast surface and spalling on the rear became more pronounced for both reinforcement types. However, while HRB400-reinforced slabs were penetrated, slabs with T63 rebar and UHPC demonstrated significantly reduced damage. Additionally, computational analysis of the damage model indicated that traditional methods underestimated the blast resistance of RC slabs with T63 high-strength rebar and UHPC.