Distributed fibre optic sensors for the purposes of structural performance monitoring

The structural design and construction industries have the potential to have a significant positive impact on the environment while at the same time reducing the cost of projects through optimized design. However, these benefits must not come at the expense of public safety or the serviceability of the structure. More comprehensive data is required to better understand the performance of structures designed using current procedures so that these procedures can be optimized. Until recently, the use of sensors during construction and operation of a building to acquire this data was difficult, expensive, and ultimately provided limited useful information. Distributed fibre optic sensors have the potential to overcome these difficulties including providing an extensive data set that can be used to more comprehensively evaluate the serviceability and ultimate limit states performance of a structure. This paper introduces the installation of a distributed fibre optic strain sensing system in a reinforced concrete commercial building. The system, based on measuring Rayleigh backscatter, enables strain to be measured with high accuracy over a gauge length that can be adjusted by the user along up to 70 m of fibre optic cable. The results of a live load test performed on a beam are introduced. The results were used to explore the beam's performance in terms of strain, deflection, flexural crack spacing, and support conditions. Distributed fibre optic sensors were found to show promise in this study, though future work is required.