Nondestructive Evaluation of FRP-Confined Concrete Using Microwave

使用微波对FRP约束混凝土进行无损评估，CMS项目0324607PI：Oral Buyukozturk，MIT纤维增强塑料(FRP)复合夹套系统已经成为钢筋混凝土柱和桥墩传统建造、加固和修复的替代方案。大量的公共和私人项目都在追求这种技术，预计将不断升级部署，特别是在地震活跃的地区。然而，一种高效和有效的结构评估技术能够评估玻璃钢夹套系统内部的具体情况。显然，需要尽快开发一种可靠的混凝土成像技术来满足迅猛增长的工业应用。本研究的目标是开发和应用有效的无损评估(NDE)成像技术，利用宽带雷达来可视化和量化FRP约束的钢筋混凝土构件中的FRP分层和混凝土开裂和崩塌等损伤。为了实现这一目标，将开发理论模型和图像重建算法设计，以实现测量数据的自动处理，同时在实验室和现场环境中进行物理模型的实验研究。还将建立各种玻璃钢、混凝土和玻璃钢-混凝土混合介质的电磁(EM)性能数据库，以促进这些发展。研究计划包括四个主要任务：(A)波传播和散射的数值模拟，(B)确定FRP、混凝土和FRP-混凝土混杂介质的介电性质，(C)物理雷达测量，以及(D)信号处理和图像重建。这四个任务本质上是紧密联系在一起的，将以迭代和进化的方式进行。在这项拟议的工作中，提出了一种使用宽带雷达的新的数据聚焦方法，以有效地检测与FRP粘结和约束钢筋混凝土系统相关的各种损伤机制。由于使用宽带雷达检测FRP约束混凝土损伤的新颖性，自2002年9月以来，根据美国国家科学基金会小额赠款探索性研究(SGER)计划，已经进行了为期一年的探索性研究，初步验证了所提出的方法的潜在能力。到目前为止，从这项探索性工作中，已经取得了可喜的结果。考虑到土木工程的非传统性质，这个项目将综合结构工程、材料科学、电子工程和计算机科学等领域的知识和理解。这一多学科的研究项目将由麻省理工学院土木工程与环境工程系、电子工程与计算机科学系、电子学研究实验室和林肯实验室合作进行。预计拟议的工作将极大地促进计算机模拟、创新成像概念、信号处理和图像重建以及处理雷达测量的实验室方法等领域的科学知识。作为制造该领域有效设备的基础的知识的发展将直接影响该行业，并使世界各地的工程师、交通基础设施社区和决策当局受益。应用所开发的知识和技术将有助于确保公共安全，防止使用玻璃钢复合材料修复或更新的结构系统发生意外故障。将通过课程课程和专业讲习班将发展的知识和方法纳入教育。将尽一切努力鼓励女性和少数族裔学生参与拟议的研究。

Nondestructive Evaluation of FRP-Confined Concrete Using Microwave, CMS project 0324607PI: Oral Buyukozturk, MITFiber-reinforced plastic (FRP) composite jacketing systems have emerged as an alternative to traditionalconstruction, strengthening, and repair of reinforced concrete columns and bridge piers. A large numberof projects, both public and private, have gone after such technology and escalating deployment has beenexpected, especially in seismically active regions. Yet, an efficient and effective structural evaluationtechnology that is capable of assessing the concrete conditions inside the FRP jacketing systems islacking. It is clear that a reliable concrete imaging technology needs to be soon developed to catch upwith the surging industrial applications.The objective of this research is to develop and apply effective nondestructive evaluation (NDE) imagingtechniques to visualize and quantify damages such as FRP delaminations and concrete cracking andcrumbling in FRP-confined reinforced concrete members using wideband radar. To achieve the objective,theoretical models and design of image reconstruction algorithms will be developed for automaticprocessing of measured data in parallel with experimental studies of physical models both in laboratoryand field settings. A database of electromagnetic (EM) properties of various FRP, concrete, and FRP-concrete hybrid media will also be established to facilitate these developments. The research plan consistsof four major tasks: (a) Numerical modeling of wave propagation and scattering, (b) Determination ofdielectric properties of FRP, concrete, and FRP-concrete hybrid media, (c) Physical radar measurement,and (d) Signal processing and image reconstruction. The four tasks are closely knitted in nature and willbe conducted in an iterative and evolutionary fashion.For this proposed work, a novel data focusing methodology using wideband radar is proposed for aneffective detection of various damage mechanisms associated with the FRP bonded and confinedreinforced concrete systems. Owing to the novelty of using wideband radar to detect damages of FRPconfined concrete, a one-year exploratory study has been underway since September 2002 under the NSF Small Grant Exploratory Research (SGER) program to initially demonstrate the potential capability of the herein proposed methodology. From this exploratory work thus far, promising results have been obtained. With this present proposal, funding is sought to fully develop the methodology and perform acomprehensive theoretical/experimental research toward achieving the objectives as stated above.Considering its non-traditional civil engineering nature, this project will synthesize the knowledge andunderstanding that has been developed in the areas of structural engineering, material science, electricalengineering and computer science. This multidisciplinary research project will be performed withcollaboration of Department of Civil and Environmental Engineering, Department of ElectricalEngineering and Computer Science, Research Laboratory of Electronics, and Lincoln Laboratory of theMassachusetts Institute of Technology.It is envisioned that the proposed work will significantly advance scientific knowledge in the areas of computer simulation, innovative imaging concepts, signal processing and image reconstruction, and laboratory methodologies dealing with radar measurements. Development of knowledge as a basis for manufacturing an effective equipment in this field will directly impact the profession, and benefit engineers, transportation infrastructure communities, and decision-making authorities worldwide. Application of the knowledge and technology developed will help ensure public safety against unanticipated failures of structural systems repaired or renewed using FRP composites. Developed knowledge and methodologies will be integrated into education via course curriculums and professional workshops. Every effort will be made to encourage female and minority student participation in the conduct of the proposed research.