Diagnostics and assessment of the structural performance of collectors and tunnels require multi-criteria as well as comprehensive analyses for improving the safety based on acquired measurement data. This paper presents the basic goals for a structural health monitoring system designed based on distributed fiber optic sensors (DFOS). The issue of selecting appropriate sensors enabling correct strain transfer is discussed hereafter, indicating both limitations of layered cables and advantages of sensors with monolithic cross-section design in terms of reliable measurements. The sensor's design determines the operation of the entire monitoring system and the usefulness of the acquired data for the engineering interpretation. The measurements and results obtained due to monolithic DFOS sensors are described hereafter on the example of real engineering structure-the Burakowski concrete collector in Warsaw during its strengthening with glass-fiber reinforced plastic (GRP) panels.
Keywords: collector; concrete; cracks; displacements; distributed fiber optic sensing DFOS; glass fiber reinforced polymer GFRP; layered cables; monolithic sensors; strains; strengthening; tunnels.