Abstract
Civil structural health monitoring (CSHM) has become significantly more important within the last decades due to rapidly growing construction volume worldwide as well as aging infrastructure and longer service lifetimes of the structures. The utilization of distributed fiber optic sensing (DFOS) allows the assessment of strain and temperature distributions continuously along the installed sensing fiber and is widely used for testing of concrete structures to detect and quantify local deficiencies like cracks. Relations to the curvature and bending behavior are however mostly excluded. This paper presents a comprehensive study of different approaches for distributed fiber optic shape sensing of concrete structures. Different DFOS sensors and installation techniques were tested within load tests of concrete beams as well as real-scale tunnel lining segments, where the installations were interrogated using fully-distributed sensing units as well as by fiber Bragg grating interrogators. The results point out significant deviations between the capabilities of the different sensing systems, but demonstrate that DFOS can enable highly reliable shape sensing of concrete structures, if the system is appropriately designed depending on the CSHM application.
Highlights
This paper introduces a comprehensive analysis of distributed fiber optic shape sensing of concrete structures
This paper introduced a comprehensive analysis of a model-free strain-based shapesensing concept along concrete structures
The capabilities of different sensor types, including numerous distributed fiber optic sensing (DFOS) cables and fiber Bragg grating (FBG) sensors, were evaluated within load tests of concrete beams as well as real-scale tunnel lining segments, where various installation techniques were used to attach the sensors along reinforcement, inside the concrete or at the structure’s surface
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. A wide range of laboratory studies on crack detection and localization using DFOS along concrete beam structures is known in literature. These discuss different sensor installation techniques, such as bonding along the beam’s surface using various sensing fibers [14] and adhesives [15], mounting cables inside the concrete [16], or gluing in grooves along reinforcement bars [17]. Basic characteristics of DFOS systems for civil engineering applications are reviewed (Section 2) and the shape-sensing algorithm, including an analysis of the DFOS’s spatial resolution impact supported by laboratory investigations, is introduced (Section 3). The outcomes are concluded and an outlook on practical SHM applications is given (Section 6)
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