Structural strengthening and seismic retrofitting of corrosion-damaged concrete structures

腐蚀损坏混凝土结构的结构加固和抗震加固

• 批准号: RGPIN-2017-04278
• 负责人: ElRefai, AHMED
• 金额: $ 1.53万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710789
• 关键词: Structural; strengthening; seismic; retrofitting; corrosion

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.

钢筋混凝土（RC）结构的延展性在地震区至关重要。此前的研究表明，钢筋因腐蚀而失去延展性，可能会发生突然失效，从而危及结构的安全。随着复合材料在强化应用中的广泛使用，由于复合材料的脆性及其可能过早脱粘，人们担心强化后截面延展性的潜在损失。 该项目提出了一种新技术，可以在不影响其延展性的情况下增强腐蚀损坏的钢筋混凝土结构。该技术的基础是通过外部粘合织物增强水泥基体 (FRCM) 系统加固受损部分，同时使用特殊配方的纤维增强混凝土，该混凝土由短切玄武岩纤维制成，称为玄武岩 MinibarsTM。所提出的技术结合了 FRCM 和玄武岩纤维增强混凝土（BFRC）的特点，以恢复受损构件的强度和延展性。 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现场应用。主题 1 包括对在中拱和下垂区域用 BFRC 修复和/或用 FRCM 加固的腐蚀损坏连续 RC 大梁进行调查。本主题将检查可能影响单调和疲劳载荷下大梁性能的各种参数。将特别关注塑料铰链的形成、旋转能力和梁的延展性。主题 2 涉及使用 BFRC 和/或 FRCM 改造抗震和腐蚀损坏的混凝土柱。柱将承受循环横向荷载以模拟地震荷载。将研究腐蚀程度、配筋率和细节、FRCM 的类型和体积分数以及 BFRC 的特性等参数。 该计划还将解决所提议的强化技术的耐久性问题。强化后样本将受到进一步腐蚀，以评估所提出技术的可持续性。此外，还将开发一种新颖的有限元模型来模拟FRCM与基材之间的界面行为；在测试过程中很难评估的行为。该模型将在混凝土混合物中使用玄武岩纤维。拟议的计划还将与魁北克省交通部讨论使用不同的 FRCM 系统进行现场试验以加固选定桥梁中受损构件的可能性。预计所提出的技术将延长国家基础设施的使用寿命，同时具有显着的社会经济效益。该计划将为执业工程师提供创新技术，以维持我们基础设施的可持续性。