Probabilistic Characterization of Bond Behavior at Rebar-Concrete Interface in Corroded RC Structures

在最近的一份报告中，国土安全部表示，基础设施老化对国家经济健康构成的危险被认为与最近的金融危机一样严重。尽管老化本身不是一种结构性故障机制，但它降低了基础设施的健壮性和抵御自然或人为危害的弹性。这项研究将集中在锈蚀对老化钢筋混凝土(RC)结构钢筋-混凝土界面粘结性能影响这一被忽略或被忽略的方面。这项研究的结果将为新的建筑环境容灾设计标准提供参考，其中允许/考虑在使用寿命期间与年龄相关的恶化，还将增强现有的状况评估工具，以全面评估老化的RC基础设施的性能，进而可用于开发用于优化资源分配的定量决策支持系统。研究的跨学科性质(包括实验和数值研究)为研究生和本科生提供了理想的学习环境，并将为学生提供急需的统计和可靠性分析工具，以进行风险管理。PI致力于通过现有的校园项目在她的机构招聘和留住未被充分代表的本科生/研究生。有两个研究目标：更好地了解腐蚀对粘结行为的影响，以及将新获得的知识应用到结构和风险分析中。因此，计划开展五项工作：(1)对单调和循环加载下考虑腐蚀的粘结性能进行全面的实验测试；(2)基于包含不确定性的试验数据评估粘结模型参数；(3)通过贝叶斯修正方法，以概率方式建立考虑腐蚀影响的粘结应力滑移本构关系；(4)将粘结劣化纳入结构分析，包括增强和增强现有设计标准，利用OpenSees对所建立的本构关系进行实施和数值验证；以及(5)进行案例研究，以研究腐蚀对风险量化的影响。这项研究将提高对与年龄相关的劣化对结构性能影响的基本理解。粘结本构模型公式考虑了普遍存在的不确定性，并提供了一种严格的方法，可在获得更多实验数据时进行更新，使不断更新的本构模型更加稳健。最重要的是，实施活动将为回弹设计的发展奠定基础，并使适当考虑老化效应的结构在极端危险下的性能研究成为可能。

In a recent report, the Department of Homeland Security stated that the dangers posed by the aging infrastructure to the nation economic health are considered to be as great as those posed by the recent financial crisis. Although aging itself is not a structural failure mechanism, it decreases infrastructure robustness and resilience against natural or man-made hazards. This research will focus on the ignored/disregarded aspect of the corrosion effect on the bond behavior at the rebar-concrete interface of aging reinforced concrete (RC) structures. The results of this research will inform new design standards for disaster resilience of the built environment, where age-related deterioration is allowed/considered during the service life, and also enhance the available condition assessment tools to holistically evaluate the performance of aging RC infrastructure, which, in turn, can be used to develop a quantitative decision support system for optimizing resource allocation. The interdisciplinary nature of the research (including experimental and numerical studies) provides an ideal learning environment for graduate and undergraduate students, and will equip the students with much-needed statistical and reliability analysis tools for risk management. The PI is committed to recruiting and retaining underrepresented undergraduate/graduate students at her institution through existing campus programs.There are two research objectives: to better understand the corrosion deterioration on bond behavior, and to implement the newly obtained knowledge into structural and risk analysis. Accordingly, five tasks are planned: (1) conduct comprehensive experimental tests on bond performance under monotonic and cyclic loading considering corrosion; (2) assess bond model parameters based on the test data incorporating uncertainties; (3) probabilistically develop the bond stress-slip constitutive law with corrosion effect through a Bayesian updating approach; (4) incorporate the bond deterioration in the structural analysis, including enhancing and augmenting the current design standards, implementing and numerically validating the developed constitutive relation using OpenSees; and (5) conduct a case study to investigate the corrosion effect on the risk quantification. The research will improve the fundamental understanding of the age related deterioration effect on structural behavior. The bond constitutive model formulation considers prevailing uncertainties and provides a rigorous means for update whenever additional experimental data is made available, making the continuously updated constitutive model more robust. Most importantly, the implementation activities will lay the groundwork for the resilience design development, and make it possible to investigate the structural performance subjected to extreme hazards with appropriate consideration of the aging effect.