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

国土安全部在最近的一份报告中指出，老化的基础设施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大。虽然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稳健性和抵御自然或人为灾害的能力。本研究将集中在被忽略/忽视的方面的腐蚀对老化钢筋混凝土（RC）结构的钢筋-混凝土界面的粘结性能的影响。这项研究的结果将通知新的设计标准的建筑环境的抗灾能力，其中年龄相关的恶化是允许/考虑在使用寿命期间，也提高了可用的条件评估工具，从整体上评估老化RC基础设施的性能，这反过来，可以用来开发一个定量的决策支持系统，优化资源配置。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，用于风险管理。PI致力于通过现有的校园项目招募和留住她所在机构的代表性不足的本科生/研究生。有两个研究目标：更好地了解腐蚀劣化对粘结性能的影响，并将新获得的知识应用于结构和风险分析。为此，本文提出了五个主要任务：（1）开展考虑腐蚀影响的单调加载和循环加载下的粘结性能综合试验研究;（2）基于试验数据对粘结模型参数进行评估;（3）采用贝叶斯概率更新方法建立考虑腐蚀影响的粘结应力-滑移本构关系;（4）在结构分析中考虑粘结劣化，包括改进和扩充现行设计标准，使用OpenSees实现和数值验证所发展的本构关系;以及（5）进行案例研究以调查腐蚀对风险量化的影响。该研究将有助于加深对老化劣化对结构性能影响的基本认识。债券本构模型的制定考虑了普遍的不确定性，并提供了一个严格的手段更新时，额外的实验数据，使不断更新的本构模型更强大。最重要的是，实施活动将为恢复力设计开发奠定基础，并使其能够在适当考虑老化效应的情况下调查极端灾害下的结构性能。

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.