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Optical Engineering

Strain distribution and crack detection in thin unbonded concrete pavement overlays with fully distributed fiber optic sensors
Author(s): Yi Bao; Genda Chen
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Paper Abstract

This study aims at evaluating the feasibility of strain measurement and crack detection in thin unbonded concrete pavement overlays with pulse prepump Brillouin optical time domain analysis. Single-mode optical fibers with two-layer and three-layer coatings, respectively, were applied as fully distributed sensors, their performances were compared with analytical predictions. They were successfully protected from damage during concrete casting of three full-scale concrete panels when 5 to 10-cm-thick protective mortar covers had been set for 2 h. Experimental results from three-point loading tests of the panels indicated that the strain distributions measured from the two types of sensors were in good agreement, and cracks can be detected at sharp peaks of the measured strain distributions. The two-layer and three-layer coated fibers can be used to measure strains up to 2.33% and 2.42% with a corresponding sensitivity of 5.43×105 and 4.66×105  GHz/μϵ, respectively. Two cracks as close as 7 to 9 cm can be clearly detected. The measured strains in optical fiber were lower than the analytical prediction by 10% to 25%. Their difference likely resulted from strain transfer through various coatings, idealized point loading, varying optical fiber embedment, and concrete heterogeneity.

Paper Details

Date Published: 20 October 2015
PDF: 8 pages
Opt. Eng. 55(1) 011008 doi: 10.1117/1.OE.55.1.011008
Published in: Optical Engineering Volume 55, Issue 1
Show Author Affiliations
Yi Bao, Missouri Univ. of Science and Technology (United States)
Genda Chen, Missouri Univ. of Science and Technology (United States)

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