Integrated Fiber Optic Sensor for Condition Monitoring of Concrete and FRP Tendons

用于混凝土和 FRP 筋状态监测的集成光纤传感器

• 批准号: 9900338
• 负责人: Farhad Ansari
• 金额: $ 23.5万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9900338&HistoricalAwards=false
• 关键词: Integrated; Fiber; Optic; Sensor; Condition

INTEGRATED FIBER OPTIC SENSOR CONDITION MONITORING OF CONCRETE AND FRP TENDONS ABSTRACT 9900338 Fiber reinforced plastics (FRP) have been employed as an alternative to conventional steel reinforcement in concrete structures. The primary attributes of FRP tendons are that of corrosion resistance reduced mass, and high tensile strength. Despite the much higher strength to weight ratios exhibited by FRP tendons, there are a number of drawbacks that hinders their widespread usage. In compare to the ductile elasto-plastic behavior of conventional steel reinforcement, the stress-strain response of FRP composites exhibit brittle behavior and are linear-elastic all the way to failure. This issue effects serviceability, design and safety of FRP tendons in concrete elements. This research program will focus attention into the development of an integrated fiber optic sensor system for condition monitoring of FRP bars. The sensor will comprise of an optical fiber with embedded partial reflectors along its length. An Optical Time Domain Reflectometer will be employed for interrogation of reflected optical signal from various regions of the structure. The fiber optic sensor system will be developed through a comprehensive research program during which the following issues will be addressed: (1) Practicality in terms of sensor confriguration for embeddment in concrete structures and simplicity of instrumentation during the condition monitoring stage. (2) Capability for seimulations detection of fiber breakage, its location, and measurement of strain gradients along the length of the member in a distributed manner. (3) Sensitivity in terms of strain amplitude and spatial resolution for characterization of damaged zone locations along the length of the FRP tendon. (4) Ruggedness for long term use during the life cycle of the structure. Performance of the proposed fiber optic system will be evaluated through an extensive experimental program involving quasi-static as well as fatigue loading of post-tensioned FRP beams. The efficacy of optical fibers in detecting, locating and evaluation of progressive damage will be investigated. A major portion of the project will involve evaluation of the system performance in terms of simultaneous detection of cracks emanating from different locations in beams. Tests will be performed to determine the level of confidence that can be achieved in correlating the fiber optic data for early detection of cracks in the FRP tendons as well as the surrounding concrete. The embedded optical fiber sensor will play a dual role. It will be employed for condition monitoring of the structure in real-time and to warn of impending failures, and for establishment of a comprehensive database pertaining to the material and structural behavior and therefore facilitate development of more realistic designs of FRP structures.

纤维增强塑料（FRP）已被用作混凝土结构中传统钢筋的替代材料。FRP筋的主要特性是耐腐蚀、减重、抗拉强度高。尽管FRP筋具有更高的强度重量比，但仍有许多缺点阻碍了其广泛使用。与传统钢筋的延性弹塑性行为相比，FRP复合材料的应力应变响应表现为脆性行为，并一直呈线弹性直至破坏。这一问题影响FRP筋在混凝土构件中的使用性能、设计和安全性。本研究项目将重点开发用于FRP筋状态监测的综合光纤传感器系统。该传感器将由一根光纤组成，沿其长度嵌入部分反射器。光时域反射计将被用于探测来自结构各个区域的反射光信号。光纤传感器系统的开发将通过一个全面的研究计划，在此期间，将解决以下问题：(1)在混凝土结构中嵌入传感器配置的实用性和状态监测阶段仪器的简洁性。(2)能够模拟检测纤维断裂及其位置，并以分布的方式测量沿构件长度的应变梯度。(3)应变幅值敏感性和空间分辨率表征FRP筋沿长度的损伤区位置。(4)结构生命周期内长期使用的坚固性。所提出的光纤系统的性能将通过一个广泛的实验项目进行评估，该实验项目涉及后张FRP梁的准静态和疲劳载荷。本文将研究光纤在连续损伤检测、定位和评估中的作用。该项目的一个主要部分将涉及评估系统性能，同时检测梁中不同位置产生的裂缝。将进行测试，以确定将光纤数据关联起来，以便早期发现FRP筋和周围混凝土的裂缝，从而达到的置信度。嵌入式光纤传感器将起到双重作用。它将用于结构的实时状态监测和即将发生的故障警告，并用于建立一个有关材料和结构行为的综合数据库，从而促进FRP结构更现实设计的发展。