Blast Performance of Reiforced Concrete Beams Constructed with High-Strength Concrete and High-Strength Reinforcement

Abstract

This thesis focuses on the dynamic and static behaviour of reinforced concrete beams built using high-strength concrete and high-strength steel reinforcement. As part of this study, a total of 8 high-strength concrete beams, built with and without steel fibres, and reinforced with high strength ASTM A1035 bars are tested under simulated blast loading using the University of Ottawa shock-tube, with an additional 3 companion beams tested under quasi-static loading. The variables considered in this study include: concrete type, fibre content, steel reinforcement ratio and steel reinforcement type. The behaviour of the beams with high-strength steel bars is compared to a companion set of beams reinforced with conventional steel reinforcement. The criteria used to evaluate the blast performance of the beams includes: overall blast capacity, maximum and residual displacements, secondary fragmentation and crack control. The dynamic results show that high strength concrete beams reinforced with high-strength steel are able to resist higher blast loads and reduce displacements when compared to companion beams with conventional steel reinforcement. The results also demonstrate that the addition of steel fibres is effective in controlling crack formation, minimizing secondary blast fragments, reducing displacements and further increasing overall blast capacity. However, the use of high-strength steel and high-strength concrete also shows potential for brittle failures under extreme blast pressures. The static results show that specimens with high-strength steel bars do not increase beam stiffness, but significantly increase peak load carrying capacity when compared to beams with the same ratio of conventional steel reinforcement. The analytical research program aims at predicting the response of the test beams using dynamic inelastic single-degree-of-freedom (SDOF) analysis and includes a sensitivity analysis examining the effect of various modelling parameters on the response predictions. Overall the analytical results demonstrate that SDOF analysis can be used to predict the blast response of beams built with high-strength concrete and steel reinforcement with acceptable accuracy.