Evaluation of distributed fibre optic sensors in structural concrete

In civil engineering, the analysis and characterisation of structural phenomena is key for the deviation of mechanical models and strongly depends on experimental studies. For this reason, the development of new measurement techniques plays a crucial role in research to allow capturing the mechanical behaviour of structures. In this context, distributed fibre optic sensing (DFOS) gained attention during the last years. Advantageous properties such as minimal invasiveness and quasi-continuous strain measurement enable new possibilities in structural monitoring. DFOS is able to sense minimal strain variations, yet this often results in recording unwanted anomalies. Thus, to generate the best results from raw measurement data, it is crucial to use a robust and reliable post-processing procedure. In order to meet this requirement, the software solution FOS Evaluator was developed using the Python programming language, targeting the most important aspects that may occur when using DFOS. Those aspects comprise a high data volume, disturbances and anomalies in the measured data and the necessity to carry out calculations with acquired data sets. In this paper, functionality and background of FOS Evaluator are presented and discussed. Furthermore, several methods for post-processing and evaluating DFOS measurements are presented, consisting of multiple functions for reducing, cleaning, or smoothing strain data, and calculating various mechanical properties from filtered measurements. Finally, the functional scope of FOS Evaluator is illustrated by various application examples in structural concrete.