Durability and Protection of Infrastructure

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Fibre Reinforced Polymers (FRP) are increasingly used as substitute for steel reinforcement in concrete structures susceptible to reinforcement corrosion, but the safe and economical design of FRP reinforced members requires knowledge of their serviceability and strength under different stress fields. Currently, there is paucity of knowledge about the load carrying capacity of FRP reinforced concrete members subjected concurrently to shear, axial load, and bending, or, to shear, torsion and bending. To fill this gap, in the proposed research the behaviour and strength of FRP reinforced concrete members under combined actions will be investigated. Physical tests will be conducted on full scale beams/columns reinforced with glass or carbon FRP bars to determine their complete behaviour, mode of failure and ultimate capacity when concurrently subjected to different levels of shear, torsion and bending or to bending, axial compression and shear. Based on the appropriate constitutive laws of concrete and FRP, as well as their bond behaviour, robust, albeit practical, rational models will be developed for the design of such members and the models will be submitted to the CSA Standard S806 for possible inclusion in the new edition of the standard. Models based on the Softened Truss Model and the Modified Compression Field Theory will be used as the starting point. ***An increasingly important area of research is the assessment and design of structures under blast loads. Among other important topics in this area is the direct shear strength of reinforced concrete (RC) members, a topic about which we know very little. The writer has observed in his field tests on RC members that brittle direct shear failure, versus diagonal tension failure, is not uncommon. Current design standards and guidelines provide little guidance about the conditions under which this mode of failure will occur and the design recommendations of the standards in this respect are not validated by actual test results. In this study, properly scaled medium size beams will be tested at different peak pressure and positive phase duration (scaled to the fundamental frequency of the member) to investigate their direct shear strength. Members with different geometry and reinforcement will be tested to identify the conditions under which this failure mode occurs and how it can be averted. Prior to the actual physical tests, detailed numerical models will be analyzed under simulated blast loads using the powerfull computer program LS-DYNA. Beams that are found to fail in direct shear will be modified to avoid this failure mode. Based on the results of the numerical models, beams will be constructed and tested in the lab using the shock tube facility at the University of Ottawa. Following the LS-DYNA results validation, detailed parametric study will be performed to further understand the phenomenon and to arrive at simplified design equations. **