Behaviour and design of concrete structures for sustainability and resilience

混凝土结构的可持续性和复原力的行为和设计

• 批准号: RGPIN-2018-06148
• 负责人: Sheikh, Shamim
• 金额: $ 2.62万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664949
• 关键词: Behaviour; design; concrete; structures; sustainability

Steel-reinforced concrete has played a critical role in the development of modern infrastructure. Unfortunately, most of the durability-related problems observed in concrete structures flow from corrosion of steel reinforcement that makes structures deficient even when the concrete is still healthy. Another issue addressed in this proposal is the alkali-silica reaction that weakens the concrete and the structure. As a result, the concrete infrastructure in most countries is in a dire state. In Canada, the problem is further exacerbated by freeze-thaw cycles and the use of de-icing salts on bridges. Residents of many cities in Canada routinely observe this phenomenon in the form of falling concrete pieces from bridges.******An economical alternative to steel reinforcement is fibre reinforced polymers (FRP) that can be used as external reinforcement to upgrade existing structures or internal reinforcement for new ones. Use of FRP as internal reinforcement in concrete slabs, beams and other flexural members has been investigated in recent years and design guidelines developed that are now available in design codes such as “Design and construction of building structures with fibre-reinforced polymers” and Canadian Highway Bridge Code. Although further work is needed and underway in many of these areas, it is the use of FRP bars to resist compressive loads that needs immediate attention. Current codes do not allow the use of FRP bars to resist compression loads in structures primarily due to a lack of experimental and analytical evidence. Another challenge in the use of FRP bars is the behaviour of bent bars, which show significant reduction in strength as a result of curvature. Code committees consider these issues as the most urgent research needs. ******The proposed work will focus on the challenges in the use of FRP in structures some of which are discussed above. The methodology includes development of analytical models for material behaviour and structural behavior. These models will be supported by, and corroborated with data from a large variety of experiments that will be conducted in state-of-the-art laboratories at the University of Toronto. Large and small specimens will be tested under realistic loads including repeated and simulated seismic forces, and will include large scale columns and beam-column joints. The small specimens made with normal and reactive ASR concrete will be used to develop constitutive models and will investigate such effects as confinement and freeze-thaw. This work will draw significantly from the work on steel-reinforced concrete members carried out by the PI over the years.******The ultimate goal is to develop design guidelines that can be included in various codes. This work would also help structural designers gain confidence in using these new materials to retrofit, design and construct more durable and sustainable infrastructure producing significant economic benefits.

型钢混凝土在现代基础设施的发展中发挥了关键作用。不幸的是，在混凝土结构中观察到的大多数与耐久性相关的问题都源于钢筋的腐蚀，这使得结构即使在混凝土仍然健康的情况下也会出现缺陷。这项建议涉及的另一个问题是碱-二氧化硅反应，它会削弱混凝土和结构。因此，大多数国家的混凝土基础设施都处于糟糕的状态。在加拿大，冻融循环和在桥梁上使用除冰盐进一步加剧了这一问题。加拿大许多城市的居民经常以混凝土碎片从桥梁上掉落的形式观察到这种现象。*钢加固的一种经济替代方案是纤维增强聚合物(FRP)，它可以用作外部加固，以升级现有结构，或用于新结构的内部加固。近年来，人们对FRP用作混凝土板、梁和其他受弯构件的内部钢筋进行了研究，并制定了设计指南，现已在设计规范中使用，如《纤维增强聚合物建筑结构的设计和施工》和加拿大公路桥梁规范。虽然其中许多领域还需要进一步的工作并正在进行中，但需要立即关注的是使用FRP筋来抵抗压缩荷载。目前的规范不允许在结构中使用FRP筋来抵抗压缩荷载，这主要是因为缺乏试验和分析证据。FRP筋使用中的另一个挑战是弯曲筋的性能，弯曲筋的强度因曲率而显著降低。代码委员会将这些问题视为最紧迫的研究需求。*拟议的工作将侧重于在结构中使用玻璃钢的挑战，其中一些已在上文讨论过。该方法包括开发材料行为和结构行为的分析模型。这些模型将由多伦多大学最先进的实验室进行的大量实验数据支持和证实。大小试件将在实际荷载下进行试验，包括重复和模拟地震力，并将包括大型柱和梁柱节点。用普通ASR混凝土和活性ASR混凝土制成的小试件将用于建立本构模型，并将研究约束和冻融等影响。这项工作将极大地借鉴国际协会多年来开展的关于钢筋混凝土构件的工作。*最终目标是制定可纳入各种规范的设计准则。这项工作还将帮助结构设计师获得信心，使用这些新材料来改造、设计和建造更耐用和可持续的基础设施，从而产生显著的经济效益。