Performance of High-Strength Reinforced Concrete Columns Under Shock-Tube Induced Blast Loading

Abstract

Accounting for blast hazards has become one of the major concerns for civil engineers when analysing and designing structures. Recent terrorist attacks and accidental explosions have demonstrated the importance of mitigating blast effects on buildings to ensure safety, preserve life and ensure structural integrity. Innovative materials such as high-strength concrete, steel fibers, and high-strength steel offer a potential solution to increase resistance against extreme dynamic loading and improve the blast resilience of buildings. This thesis presents the results of an experimental and analytical study examining the effect of high-strength concrete, high-strength reinforcement and steel fibers on the blast behaviour of reinforced concrete columns. As part of the study, a total of seventeen reinforced concrete columns with different design combinations of concrete, steel fibers, and steel reinforcement were designed, constructed, and tested under gradually increasing blast loads using the University of Ottawa shock-tube facility. Criteria used to assess the blast performance of the columns and the effect of the test variables included overall blast capacity, mid-span displacements, cracking patterns, secondary fragmentation, and failure modes. The effect of concrete strength was found to only have a moderate effect on the blast performance of the columns. However, the results showed that benefits are associated with the combined use of high-strength concrete with steel fibers and high-strength reinforcement in columns tested under blast loads. In addition to the experimental program, a dynamic inelastic single-degree-of-freedom analysis was performed to predict the displacement response of the test columns. A sensitivity analysis was also conducted to examine the effect of various modelling parameters such as materials models, DIFs, and accumulated damage on the analytical predictions.