Blast resistance of hybrid steel and polypropylene fibre reinforced ultra-high performance concrete after exposure to elevated temperatures

In this study, the blast resistance of fibre reinforced ultra-high performance concrete (UHPC) components after exposure to elevated temperatures was investigated. With a hybrid steel and polypropylene (PP) fibre reinforcement, this fire resistant UHPC maintained approximately 60% of its original compressive strength after exposed to 800 °C temperature. Uniaxial and triaxial material behaviour after exposure to high temperatures was studied experimentally and then incorporated into a plasticity concrete model, i.e. Karagozian & Case Concrete (KCC model) model for the blast induced structural response analysis. Material strength and failure surfaces, volumetric change with pressure, strain rate effect and material damage parameters were updated with consideration of fire hazards. The simulated UHPC uniaxial stress–strain curves after exposure to 200, 400, 600 and 800 °C elevated temperatures, together with the simulated post-fire blast tests results on UHPC members were compared with available experimental results. The reasonable agreement between the tests and simulation results validated the proposed model in both material and structural scopes. The numerical model was further applied to predict the blast response of reinforced UHPC components after exposed to thermal hazards.