Durability and Protection of Infrastructure

在易受钢筋锈蚀的混凝土结构中，纤维增强聚合物(FRP)越来越多地被用作钢筋的替代品，但FRP加固构件的安全经济设计需要了解其在不同应力场下的使用性能和强度。目前，关于FRP筋混凝土构件在剪切、轴压和弯曲或剪切、扭转和弯曲共同作用下的承载能力知之甚少。为了填补这一空白，在拟议的研究中，将研究FRP钢筋混凝土构件在联合作用下的性能和强度。将对用玻璃或碳纤维增强筋加固的足尺梁/柱进行物理测试，以确定其在同时承受不同程度的剪切、扭转和弯曲或弯曲、轴压和剪切时的完整性能、破坏模式和极限承载力。基于混凝土和FRP的适当本构关系以及它们的粘结性能，将为此类构件的设计开发稳健的、尽管实用的合理模型，并将这些模型提交给CSA标准S806，以便可能包括在新版本的标准中。基于软化桁架模型和修正的压力场理论的模型将被用作起点。*一个日益重要的研究领域是爆炸荷载下结构的评估和设计。在这一领域的其他重要课题之一是钢筋混凝土(RC)构件的直接剪切强度，这是一个我们知之甚少的话题。作者在钢筋混凝土构件的现场试验中观察到，脆性直接剪切破坏与斜拉破坏并不少见。目前的设计标准和准则对发生这种失效模式的条件提供的指导很少，标准在这方面的设计建议没有得到实际试验结果的验证。在这项研究中，适当比例的中型梁将在不同的峰值压力和正相持续时间(按构件的基频)下进行试验，以研究其直接抗剪强度。将对具有不同几何形状和配筋的构件进行测试，以确定发生这种失效模式的条件以及如何避免它。在实际物理试验之前，将使用功能强大的计算机程序LS-DYNA在模拟爆炸载荷下分析详细的数值模型。被发现在直剪中失效的梁将被修改以避免这种失效模式。根据数值模型的结果，将使用渥太华大学的激波管设施在实验室构建和测试波束。在LS-DYNA结果验证之后，将进行详细的参数研究，以进一步了解这一现象并得出简化的设计公式。**

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. **