Structural strengthening and seismic retrofitting of corrosion-damaged concrete structures

钢筋混凝土结构的延性在地震区是至关重要的。以往的研究表明，钢筋由于锈蚀而失去延性，可能会发生突然破坏，从而危及结构的安全。随着复合材料在加固应用中的广泛应用，由于复合材料的脆性和可能的过早剥离，人们对加固后截面延性的潜在损失感到担忧。*本计划提出了一种新的技术，在不影响其延性的情况下加固受腐蚀损坏的RC结构。这项技术的基础是用外部粘结的织物增强水泥基(FRCM)系统加固受损部分，同时使用由被称为玄武岩MinibarsTM的短玄武岩纤维制成的特殊配方的纤维增强混凝土。该技术结合了FRCM和玄武岩纤维混凝土(BFRC)的特点，以恢复受损构件的强度和延性。*将进行两个主题，每个主题包括实验室测试、数值或分析建模以及实地应用。主题1包括对在拱顶和下垂区域用BFRC修复和/或FRCM加固的腐蚀损坏的连续RC梁的调查。本主题将研究在单调和疲劳荷载作用下可能影响主梁性能的各种参数。将特别注意塑性铰链的形成、旋转能力和梁的延性。主题2涉及使用BFRC和/或FRCM对抗震不足和腐蚀损坏的混凝土柱进行翻新。柱子将承受循环水平荷载，以模拟地震荷载。研究的参数包括锈蚀程度、配筋率和配筋率、FRCM的类型和体积分数以及BFRC的特性。*该计划还将解决拟议加固技术的耐久性问题。加固后的试件将暴露在进一步的腐蚀中，以评估拟议技术的可持续性。此外，还将开发一种新的有限元模型来模拟FRCM和衬底之间的界面行为；这一行为在测试期间很难评估。该模型将在混凝土搅拌中加入玄武岩纤维的使用。还将与魁北克交通部讨论拟议的计划，以确定使用不同的FRCM系统进行现场试验的可能性，以加固选定桥梁中的受损部件。预计拟议的技术将延长国家基础设施的使用寿命，同时具有显著的社会经济效益。该计划将为执业工程师提供一种创新技术，以保持我们基础设施的可持续性。

Ductility of reinforced concrete (RC) structures is crucial in seismic regions. Previous research has shown that steel bars lose their ductility due to corrosion and abrupt failure may occur, thus jeopardizing the structure's safety. With the wide use of composites in strengthening applications, concerns about the potential loss of section's ductility after strengthening are raised due to the brittle nature of composites and their likely premature debonding. ***This program proposes a novel technique to strengthen corrosion-damaged RC structures without compromising their ductility. The technique is based on strengthening the damaged sections with externally bonded Fabric-Reinforced Cementitious Matrix (FRCM) systems while using specially formulated fiber-reinforced concrete made with chopped basalt fibers known as basalt MinibarsTM. The proposed technique combines the features of FRCM and those of basalt-fiber reinforced concrete (BFRC) to restore the strength and ductility of the damaged member. ***Two themes, each consisting of laboratory testing, numerical or analytical modeling, and field applications will be conducted. Theme 1 comprises an investigation on corrosion-damaged continuous RC girders repaired with BFRC and/or strengthened with FRCM in both the hogging and sagging regions. This theme will examine various parameters that are likely to affect the performance of the girders under monotonic and fatigue loading. Special attention will be given to the formation of plastic hinges, the rotational capacity, and the ductility of the girder. Theme 2 involves the retrofitting of seismically-deficient and corrosion-damaged concrete columns with BFRC and/or FRCM. The columns will be subjected to cyclic lateral loads to simulate seismic loading. Parameters such as the corrosion level, reinforcement ratios and details, the type and volume fraction of FRCM, and the characteristics of BFRC will be investigated. ***The program will also address the durability of the proposed strengthening technique. Specimens will be exposed to further corrosion after strengthening to assess the sustainability of the proposed technique. In addition, a novel finite element model will be developed to simulate the interfacial behavior between FRCM and the substrate; a behavior that is difficult to assess during the tests. The model will incorporate the use of basalt fibers in the concrete mix. The proposed program will also be discussed with the Ministry of Transportation in Quebec for the possibility of conducting field trials using different FRCM systems to strengthen damaged elements in selected bridges. It is expected that the proposed technique will extend the service life of the nation's infrastructure, while having significant socio-economic benefits. The program will provide practicing engineers with an innovative technique that will maintain the sustainability of our infrastructure.