Real-time Intelligent Monitoring of Reinforced Concrete Structures

钢筋混凝土结构的实时智能监测，CMS提案0301441 PI：Yuan，NC State UniversityWith a growing concern on the过早恶化的民用基础设施系统，在量化物理条件的发展战略的需求不断增加。 钢筋混凝土（RC）结构是一种结构复杂、体积庞大、使用寿命长、环境恶劣的结构。钢筋混凝土结构退化的主要原因是混凝土中钢筋的腐蚀破坏。额外的腐蚀诱发裂缝，导致钢筋脱粘。钢筋混凝土结构中这种形式的劣化往往超过其他形式的劣化。尽管钢筋混凝土结构存在潜在的损伤，有时甚至是灾难性的损伤，但目前仍然缺乏一种有效的结构健康监测系统（SHMS）来提供钢筋混凝土结构内部损伤的定量信息。 显然，需要开发一个强大的监测系统，以便为土木结构提供及时的维护行动和安全。本研究的目的是开发一种主动分布式传感系统，用于真实的实时量化和可视化钢筋混凝土结构中嵌入式损伤的位置和大小。这项工作不仅仅是一个简单的监测系统;它只是检测损坏的存在，而不确定其对结构安全的重要性。 拟议的工作建立在一项概念验证研究的基础上，其中PI展示了利用迁移技术识别不同大小和形状的损伤及其在金属中的位置，该技术广泛用于地球物理勘探。在这项工作中，一个线性阵列的压电片类似的地震检波器被用于实验中的致动器和传感器。有了这个初步的成功，在均匀的板，拟议的研究旨在量化的损害，在高度不均匀的钢筋混凝土结构，特别是腐蚀和裂纹引起的剥离钢筋混凝土使用分布式压电致动器/光纤光栅传感器网络。激励信号将从安装在混凝土或钢筋上的压电致动器发出;低成本和可靠的光纤分布式传感器将嵌入混凝土中，以提供沿着其长度的钢筋混凝土动态应变传感。研究计划包括四项主要任务。即： 利用射线理论为波传播建模和散射开发一种可靠的实时叠前偏移技术 原型钢筋混凝土结构物理模型的实验室测量;腐蚀/脱粘对选择性诊断信号以及压电和光纤放置的敏感性的测定;信号处理技术和成像可视化算法的开发，用于以高分辨率明确识别损伤的位置和大小。这项研究将确定和解决基本的科学和工程的挑战，建立SHMS在钢筋混凝土结构。该研究将为今后利用位移技术实现分布式压电驱动器/光纤光栅传感器网络的损伤识别和连续监测奠定基础。 据设想，拟议的工作将大大推进传感器技术，应力波模拟，创新的迁移技术，损伤重建和可视化，以及实验室方法与应力波测量领域的科学知识。 将通过开设相关课程和举办专业讲习班，将已开发的知识和方法纳入教育。 通过本科生参与实验室测试和分析的实验工作，研究生的研究工作将与本科课程相结合。通过与北卡罗来纳州AT大学（一所历史悠久的黑人大学）的现有联系，将努力吸引女性和少数民族学生进行拟议的研究。 此外，通过机械和航空航天工程系现有的工业合作伙伴计划，工业合作伙伴将作为研究生论文委员会成员参与其他相关工作。

Real-time Intelligent Monitoring of Reinforced Concrete Structures, CMS proposal 0301441PI: Yuan, NC State UniversityWith a growing concern on the premature deterioration of civil infrastructure systems, the demand for the development of strategies in quantifying physical condition is ever increasing. The widely used steel-reinforced concrete (RC) structures are normally massive and complex and are subjected to harsh environment for a rather long service life. The leading cause of degradation of RC structures is corrosion damage to the rebar embedded in the concrete. Additional corrosion induces cracks leading to debonding of the rebar. This form of deterioration in RC structures often outweighs other forms of deterioration. Despite the potential damages, and sometimes potentially catastrophic ones, an efficient and effective structural health monitoring system (SHMS) that provides quantitative information of damage inside RC structures is still lacking. It is clear that a robust monitoring system needs to be developed to provide timely maintenance action and safety for civil structures. The objective of this research is to develop an active distributed sensing system for quantifying and visualizing location and sizing of embedded damage in RC structures in real time. The work goes beyond a simple monitoring system; it merely detects the presence of damage without identifying its importance on the safety of the structure. The proposed work builds on a proof-of-concept study in which the PI demonstrated the identification of different sizes and shapes of damages and their locations in metals utilizing migration technique, which is widely used in geophysical exploration. In that work, a linear array of piezoelectric patches analogous to the geophones was used in the experiments as actuators and sensors. With this preliminary success in homogeneous plates, the proposed research aims at quantifying the damage in highly inhomogeneous RC structures, in particular the corrosion and crack-induced debonding of the rebars from the concrete using a distributed piezo actuator/FBG sensor network. Excitation signals will be emitted from piezo actuators, either mounted on the concrete or on the rebars; low-cost and reliable optical fiber distributed sensors will be embedded in the concrete to provide dynamic strain sensing along their lengths for reinforced concrete. The research plan consists of four major tasks. Namely: Development of a robust and real-time prestack migration technique using ray theory for wave propagation modeling and scattering; Laboratory measurements of physical models of prototype RC structures; Determination of sensitivity of corrosion/debonding to selective diagnostic signals and to piezo and optical fiber placement; Development of signal processing techniques and imaging visualization algorithms for unambiguous identification in location and sizing of the damages with high resolution. This study will identify and address basic scientific and engineering challenges toward establishing SHMS in RC structures. The proposed research will lay the groundwork for the future use of a distributed piezo actuator/FBG sensor network for damage identification and continuous monitoring using migration technique. It is envisioned that the proposed work will significantly advance scientific knowledge in the areas of sensor technology, stress wave simulation, innovative migration technique, damage reconstruction and visualization, and laboratory methodologies with stress wave measurements. Developed knowledge and methodologies will be integrated into education via development of relevant courses and professional workshops. Through involvement of undergraduate students in the experimental work in the laboratory testing and analysis, the graduate research work will be integrated with undergraduate program. Through existing ties with North Carolina A&T University, a historically black university, effort will be made to attract female and minority students in performing the proposed research. Moreover, through an existing Industrial Partnership Program in the Department of Mechanical and Aerospace Engineering, industrial partners will be involved as members of the graduate thesis committee in other relevant work.