Fiber Optic Sensing for Monitoring Corrosion-Induced Damage

Abstract

This paper reports the feasibility of using embedded Fabry-Pé rot fiber optic sensors to detect and monitor the propagation of cracks and delamination within concrete beams induced by corrosion of the reinforcing bars. In this research, four series of reinforced concrete beams were subjected to varying degrees of corrosion-induced damage by modifying the composition of the concrete mix and subjecting all specimens to the same accelerated corrosion environment. The concept employed in this study involves embedding the Fabry-Pé rot sensor between two reinforcing bars to measure the transverse tensile strains associated with the longitudinal crack along the reinforcing bars (and in severe cases, delamination of the concrete beam) resulting from the radial expansion of the corroding rebars. Excellent correlation was obtained between the Fabry-Pé rot strain data and the amount of steel loss resulting from accelerated corrosion. In addition, the optical sensor strain readings and the reductions in the load-carrying and deflection capacities were also observed to exhibit strong positive correlation highlighting the potential of the optical sensor to monitor the progression of the rebar damage and the loss of structural integrity of the beams resulting from the extensive corrosion. The technique used in this study demonstrates the possibility of detecting corrosion-induced damage in reinforced concrete structures, particularly those where visual inspection is not possible.

Development and laboratory validation of in-line multiplexed low-coherence interferometric sensors

“…Consistent with Eqs. (15) and (19), in this and in the following graphs the measured peak shifts p * k and field elongations f * k are those calculated taking into account constant n CD and strain sensitivity S ε , which is to say:…”

“…As another example, Blue Road Research and the University of California, San Diego, have been collaborating over several years to develop a system employing FBG strain sensors and modal analysis to provide real-time quantitative information on dynamic bridge response [14]. Other FBG-based FOS (either long or short gauges) are suggested by Maalej et al [15]. Whatever the solution, it is clear that the effectiveness of the system is based on the assumption that the intermediate structure will deform uniformly, so that the strain measured at the FBG can be extended to the whole length of the gauge.…”

Optical Sensors for Corrosion Monitoring

“…A few works have studied FBGs strain sensors to monitor the corrosion rate in civil engineering structures at single or multiple points. [28][29][30][31][32] In particular, the location of the sensor in Ref. [26] it is presented and experimentally demonstrated the utilization of a new fiber glass-reinforced polymer (FGRP) optical fiber Bragg gratings (OFBG), which is merged within the stay cable (see Figure 18.6) in bridges for corrosion detection.…”

“…[23][24][25][26][27] In Ref. [29] enables the detection of tensile strain perpendicularly to the plane of the reinforced steel bars. This work shows the importance of the optical fiber embodiment and armor in order to withstand the harsh working conditions and obtain large durability of the sensor.…”

An inverse solution for reconstruction of the area-moment-of-inertia of a beam using deflection data

“…In the earlier stages of SHM research, the primary focus was on non-destructive testing [20,21] with emphasis on reinforced concrete beams and bridges [22,23]. Moreover, sensors and instrumentation were developed to improve the quality of measurement response [24,25].…”