Distributed fiber optic strain sensing of bending deformation of a well mockup in the laboratory

Sasaki, T.; Zhang, Shenghan; Soga, Kenichi; Luo, Linqing; Freifeld, Barry; Kitayama, Yoki; Kawaguchi, Kyojiro; Sugiyama, Hiroshi

doi:10.1016/j.jngse.2021.104309

Cited by 12 publications

(5 citation statements)

References 45 publications

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“…One emerging DFOS technology, Optical Frequency Domain Reflectometry (OFDR), is especially suitable for this task due to its unprecedented spatial resolution (around 1 mm) and high accuracy (around 1

). Since its appearance a few years ago, it has been used in structural engineering laboratories around the world [ 7 , 8 , 9 , 10 , 11 ]. For a detailed review, please refer to Bado and Casas [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Distributed Fiber-Optic Strain Sensing of an Innovative Reinforced Concrete Beam–Column Connection

Zhang

Liu

Darwish

et al. 2022

Sensors

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Distributed fiber-optic sensing (DFOS) technologies have been used for decades to detect damage in infrastructure. One recent DFOS technology, Optical Frequency Domain Reflectometry (OFDR), has attracted attention from the structural engineering community because its high spatial resolution and refined accuracy could enable new monitoring possibilities and new insight regarding the behavior of reinforced concrete (RC) structures. The current research project explores the ability and potential of OFDR to measure distributed strain in RC structures through laboratory tests on an innovative beam–column connection, in which a partial slot joint was introduced between the beam and the column to control damage. In the test specimen, fiber-optic cables were embedded in both the steel reinforcement and concrete. The specimen was tested under quasi-static cyclic loading with increasing displacement demand at the structural laboratory of the Pacific Earthquake Engineering Research (PEER) Center of UC Berkeley. Different types of fiber-optic cables were embedded both in the concrete and the rebar. The influence of the cable coating and cable position are discussed. The DFOS results are compared with traditional measurements (DIC and LVDT). The high resolution of DFOS at small deformations provides new insights regarding the mechanical behavior of the slotted RC beam–column connection, including direct measurement of beam curvature, rebar deformation, and slot opening and closing. A major contribution of this work is the quantification of the performance and limitations of the DFOS system under large cyclic strains. Performance is quantified in terms of non-valid points (which occur in large strains when the DFOS analyzer does not return a strain value), maximum strain that can be reliably measured, crack width that causes cable rupture, and the effect of the cable coating on the measurements. Structural damage indices are also proposed based on the DFOS results. These damage indices correlate reasonably well with the maximum sustained drift, indicating the potential of using DFOS for RC structural damage assessment. The experimental data set is made publicly available.

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Section: Introductionmentioning

confidence: 99%

Distributed Fiber-Optic Strain Sensing of an Innovative Reinforced Concrete Beam–Column Connection

Zhang

Liu

Darwish

et al. 2022

Sensors

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“…The authors also concluded that a reduced number of coating layers and tight buffering around optical fibres contributed to higher measurement accuracy. This work was developed further to study characteristics of fibre-optic cables that affect the accuracy of BOTDR/BOTDA and OFDR measurements [50]. A similar setup to the one described in [47] was used with a three-point loading in three different directions.…”

Section: Condition Monitoringmentioning

confidence: 99%

Use of Fibre-Optic Sensors for Pipe Condition and Hydraulics Measurements: A Review

et al. 2022

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The combined length of the sewerage and clean water pipe infrastructure in the UK is estimated to be about 800,000 km. It is prone to failure due to its age and the inadequacies of the current pipe inspection methods. Fibre-optic cable sensing is an attractive way to continuously monitor this infrastructure to detect critical changes. This paper reviews the existing fibre-optic sensor (FOS) technologies to suggest that these technologies have better sensing potential than traditional inspection and performance monitoring methods. This review also discusses the requirements for retrofitting an existing pipeline with an FOS. It also demonstrates that there is a need for further research into methods applicable to non-pressurised pipelines, as there is very little existing literature that focuses on partially filled pipes and pipes with gravity fed flows.

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“…Brillouin optical time-domain reflectors (BOTDR) are used to realize distributed optical fiber sensing by using the linear relationship of the Brillouin frequency shift (BFS) versus the change in temperature and strain [1]. It has wide applications [2,3], such as security monitoring of buildings [4], wells [5], marine structures [6], power cables, and traffic facilities [7,8].…”

Section: Introductionmentioning

confidence: 99%

High-Precision Measurement of Brillouin Frequency Shift in Brillouin Optical Time-Domain Reflectometer Based on Half-Peak Fitting Algorithm of Power Spectrum

Dong

Shan

et al. 2023

IEEE Access

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The Brillouin optical time-domain reflectometer (BOTDR) system, which is based on the Brillouin frequency shift (BFS) of the scattering spectrum, has been widely applied to monitor the temperature and strain in many fields. The measurement accuracy of the BFS directly affects the monitoring and location of the temperature change or strain events. In this study, the characteristics of the least-squares fitting optimal solution of the Brillouin power spectrum are theoretically investigated, and a half-peak fitting algorithm is proposed to measure the BFS with high accuracy and stability. In particular, it can precisely determine the double-peak spectrum and detect the position in the transition section of a temperature change or strain event. Furthermore, it can reduce calculation complexity and enhance measurement speed by dropping most of the data. For the fiber under test (FUT) with a length of 12-km, 200 groups of time-domain data were processed using a probe pulse of width 50 ns and sampling rate 1 GHz. The half-peak fitting algorithm increased the temperature measurement accuracy by ~1 fold, with ~20% calculation of full fitting. Meanwhile, it effectively eliminated the influence of minor peak in the doublepeak spectrum, and optimized the spatial resolution of the temperature change position to 0.1-m, which is the maximum limitation by sampling rate.

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Distributed fiber optic strain sensing of bending deformation of a well mockup in the laboratory

Cited by 12 publications

References 45 publications

Distributed Fiber-Optic Strain Sensing of an Innovative Reinforced Concrete Beam–Column Connection

Distributed Fiber-Optic Strain Sensing of an Innovative Reinforced Concrete Beam–Column Connection

Use of Fibre-Optic Sensors for Pipe Condition and Hydraulics Measurements: A Review

High-Precision Measurement of Brillouin Frequency Shift in Brillouin Optical Time-Domain Reflectometer Based on Half-Peak Fitting Algorithm of Power Spectrum

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