Abstract
Early detection of crack is critical for the maintenance of reinforced concrete (RC) structures. In this study, a distributed optical fiber (DOF) sensing system with Rayleigh Optical Frequency Domain Reflectometry (OFDR) technique was deployed to a member of RC structure in a full-scale laboratory experiment, which was subjected to a monotonic lateral load. With the aid of a high space resolution (up to 1 mm) and measurement accuracy (±1 micro strain) interrogator (OSI-S by Semicon), continuous strain measurements inside of the RC member are elaborately implemented. The result of crack detection by the analysis of the measured tensile strain profiles is in excellent agreement with the visually observable cracks mapped during the test. This confirms the ability of the optical fiber inside of RC members to capture cracks on concrete surface. Moreover, the recognition of crack orientation and depth is accomplished by comparing strain measurements of optical fibers installed at multiple locations.
Highlights
Because of inherent weakness in tension, cracks can be observed in reinforced structures even in service loading
Recent case histories have demonstrated the feasibility of distributed optical fiber (DOF) sensing system with Rayleigh Optical Frequency Domain Reflectometry (OFDR) technique in the crack detection of concrete structures [3,4,5,6,7,8,9,10,11,12]. e DOF sensing system employs optical fibers as sensing elements to continuously measure the strain along the entire fiber length
A distributed optical fiber-based concrete crack monitoring scheme was proposed, especially for the cases where concrete was confined in a container without a visible surface, while its cracking was a critical issue with great concern. e checking of its effectiveness was carried out in a heavily reinforced concrete (RC) structure subjected to a concentrated load, a wall-beam-strut joint experiment at full scale
Summary
Because of inherent weakness in tension, cracks can be observed in reinforced structures even in service loading. Fibers were attached to reinforcement bars that will later be embedded in concrete to capture strains along the length of rebar in some experiments [6, 7, 13,14,15], and it is demonstrated that the reinforcement strains recorded by optical fiber correlate perfectly with the position and opening of the cracks all over the concrete surface [6]. In this context, a distributed optical fiber-based concrete crack monitoring scheme was proposed, especially for the cases where concrete was confined in a container without a visible surface (see Figure 1), while its cracking was a critical issue with great concern. The experimental crack mapping observed during the test will be compared
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