Institute of Structural Engineering (IBK), Swiss Federal Institute of Technology Zurich (ETHZ), Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland.
Sensors (Basel). 2021 Nov 17;21(22):7643. doi: 10.3390/s21227643.
Distributed fibre optical sensing (DFOS) allows for quasi-continuous strain measurement in a broad range of gauge lengths and measurement frequencies. In particular, Rayleigh backscatter-based coherent optical frequency domain reflectometry has recently registered a significant application increase in structural concrete research and monitoring thanks to its numerous merits, such as high resolution and low invasiveness. However, it is not a plug-and-play technique. The quality of the acquired data depends highly on the choice of the fibre optical sensor and the methods of instrumentation and post-processing. Furthermore, its unprecedented resolution and sensitivity allow capturing local effects not well documented so far. This paper analyses the suitability of DFOS based on Rayleigh backscatter for reliably measuring strains and discusses the origin and structural relevance of local variations in the results. A series of experimental investigations are presented, comprising tensile tests on bare reinforcing bars and concrete compression tests. A critical analysis of the results leads to a best practice for applying DFOS to reinforcing bars and concrete, which establishes a basis for reliable, accurate measurements in structural concrete applications with bonded reinforcement.
分布式光纤传感（DFOS）允许在广泛的测量长度和测量频率范围内进行准连续应变测量。特别是，基于瑞利背向散射的相干光频域反射计由于其众多优点，如高分辨率和低侵入性，在结构混凝土研究和监测方面的应用最近显著增加。然而，它不是即插即用的技术。所获得数据的质量在很大程度上取决于光纤传感器的选择以及仪器和后处理方法。此外，它前所未有的分辨率和灵敏度允许捕获迄今为止尚未详细记录的局部效应。本文分析了基于瑞利背向散射的 DFOS 可靠测量应变的适用性，并讨论了结果中局部变化的来源和结构相关性。介绍了一系列实验研究，包括对裸钢筋的拉伸试验和混凝土压缩试验。对结果的批判性分析得出了将 DFOS 应用于钢筋和混凝土的最佳实践，为在具有粘结钢筋的结构混凝土应用中进行可靠、准确的测量奠定了基础。
