Moisture Affected Debonding in FRP Retrofitted Concrete Systems - An Interface Fracture Approach

05110797 Buyukozturk虽然FRP（纤维增强聚合物）加固混凝土系统的剥离研究已经广泛地进行了短期力学表征，但有关这种剥离行为的长期性能和耐久性问题仍然很大程度上不确定和没有答案。特别是，鲜为人知的是，关于水分对粘结性能和FRP加固混凝土的完整性，将管理这些系统的有效性和生命周期的影响。本研究的目的是开发一个深入的力学理解的水分影响剥离CFRP（碳纤维增强聚合物）镀混凝土使用界面断裂的方法，严格量化的剥离问题，通过界面断裂韧性的粘结系统。虽然强度方法能够量化和分析材料脱粘类型的脱粘，但它本质上缺乏描述粘附相关现象的能力。界面断裂韧性，另一方面，被认为是多层材料系统的粘结性能，是一个量化参数的中心，这项拟议的研究。我们建议通过协同努力进行调查，包括系统和分层的材料和界面断裂测试和分析调查。将进行水分循环和粘弹性效应下脱粘的分析建模，包括三维水分扩散模拟的数值研究，包括扭结标准实施和模式混合表征的界面断裂分析，以及相关性研究，以在梁尺度上绘制局部断裂能和外部载荷配置之间的联系。韧性参数，这将在整个研究中使用，将计算从最近开发的模型从以前的NSF资助的研究由PI的研究小组，这是能够描述的三层材料的问题，包括FRP，环氧树脂和混凝土。预计从这项研究中开发的基本知识将形成的基础上，增加现有的设计规范FRP加固混凝土结构的水分影响，在这样的系统。

05110797BuyukozturkWhile research on debonding of FRP (fiber reinforced polymer) retrofitted concrete systems have been conducted extensively for short-term mechanical characterization, long-term performance and durability issues regarding such debonding behavior remain largely uncertain and unanswered. In particular, little is known with regard to the effect of moisture on bond properties and integrity of FRP retrofitted concrete that would govern the effectiveness and life cycle of these systems. The objective of this research is to develop an in-depth mechanistic understanding of moisture affected debonding in CFRP (carbon fiber reinforced polymer) plated concrete using an interface fracture approach, which rigorously quantifies the debonding problem by means of interface fracture toughness of the bonded system. While the strength approach is capable of quantifying and analyzing material decohesion type of debonding, it intrinsically lacks the ability to describe adhesion related phenomena. Interface fracture toughness is, on the other hand, considered a bond property of the multi-layer material system, and is a quantification parameter central to this proposed research. We propose to conduct the investigation by means of a synergistic effort that consists of systematic and hierarchical material and interface fracture testing and analytical investigation. Analytical modeling of debonding under moisture cyclic and viscoelastic effects, numerical studies that consist of three-dimensional moisture diffusion simulation, interface fracture analysis that consists of kink criterion implementation and mode-mix characterization will be performed, as well as correlation studies to draw links between local fracture energy and external load configurations at the beam scale. The toughness parameter, which will be used throughout the study, will be computed from a model recently developed from prior NSF-funded research by the research group of the PI, that is capable of describing the tri-layer material problem consisting of FRP, epoxy, and concrete. It is expected that the fundamental knowledge to be developed from this research will form the basis for augmenting existing design specifications for FRP retrofitted concrete structures by accounting for moisture effects in such systems.