First-time demonstration of measuring concrete prestress levels with metal packaged fibre optic sensors

Mckeeman, I.; Fusiek, Grzegorz; Perry, Marcus; Johnston, Michael B.; Saafi, Mohamed; Niewczas, Paweł; Walsh, M.P.; Khan, Saeed Ahmed

doi:10.1088/0964-1726/25/9/095051

Cited by 19 publications

(19 citation statements)

References 27 publications

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“…Similarly to [9], the braze-welded design consists of a metal coated FBG within a kovar capillary, brazed between two metal shims. In this work, the 0.05 mm thick carbon steel shims as reported in [9] were replaced with 0.2 mm thick magnetic stainless steel (MSS) plates as the sensors were welded to a flat surface.…”

Section: B Braze-welded Attachmentmentioning

confidence: 99%

“…In this work, the 0.05 mm thick carbon steel shims as reported in [9] were replaced with 0.2 mm thick magnetic stainless steel (MSS) plates as the sensors were welded to a flat surface. This provided additional corrosion protection.…”

Section: B Braze-welded Attachmentmentioning

confidence: 99%

“…FBGs also boast a long-life capability and have been used extensively for strain and displacement monitoring in many industries, such as civil engineering [3][4][5], aerospace [6], as well as oil and gas [7]; most of which use epoxy based attachment methods. In previous work, brazed metal packaged FBGs [8] were used to monitor prestress in concrete [9] and for displacement measurement in spalled concrete [10].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of epoxy and braze-welded attachment methods for FBG strain gauges

et al. 2017

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This version is available at https://strathprints.strath.ac.uk/62475/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Abstract-This paper presents experimental results from fatigue and static loading tests performed on both epoxy and braze-welded FBG strain sensors. Most FBG attachment methods are relatively understudied, with epoxy the most commonly used. Long curing times and humidity sensitivity during curing render epoxy inappropriate for certain implementations. This work shows that a bespoke braze-welded attachment design is able to achieve a higher static failure limit of 22kN when compared to strain gauge epoxies, which fail at 20kN. Both methods demonstrate high fatigue life, with no significant deterioration after two million cycles. Epoxy swelling was observed when the sensors were held at a relative humidity of 96%, applying ~0.6 m of tension to the FBG, whereas a braze-weld attachment was unaffected by humidity.

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Section: B Braze-welded Attachmentmentioning

confidence: 99%

Section: B Braze-welded Attachmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of epoxy and braze-welded attachment methods for FBG strain gauges

et al. 2017

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“…Since such steel strands are the most important member of the PSC structure, their rupture is likely to degrade structural health. It is noteworthy that, despite its primary role, it has been challenging to directly measure the prestress distribution within the structure prior to the development of the smart strand [1][2][3][4][5]. The prestress force was estimated indirectly by a formula calculating the loss of prestress using the hydraulic pressure measured externally at the jacked end of the structure and the change in the length of the tendon before and after prestressing [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…The smart strand can be fabricated by attaching the optical fiber between the neighboring helical wires [4,5] or by replacing the steel core wire with a core wire in which the optical fiber is embedded. In such case, the core wire is made by inserting the optical fiber inside a hollow steel tube [2] or by pultruding a carbon fiber reinforced polymer (CFRP) rod [1] or a glass fiber reinforced polymer (GFRP) rod [3] with the optical fiber monolithically.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Tendon Force Distribution in Prestressed Concrete Girders Using Smart Strand

et al. 2017

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Abstract:The recently developed smart strand offers the possibility of measuring the prestress force of the tendon from jacking and all along its service life. In the present study, a method estimating the force distribution in all the tendons of a prestressed concrete (PSC) girder installed with one smart strand is proposed. The force distribution in the prestressed tendons is formulated by the friction and the anchorage slip, and is obtained through an optimization process with respect to the compatibility conditions and equilibrium of the forces in the section of the PSC girder. The validation of the proposed method through a numerical example and experiment shows that it can be used to estimate the force developed in the tendon.

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Monitoring of prestressing forces in prestressed concrete structures—An overview

Abdel-Jaber

Glišić

2019

Struct Control Health Monit

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This paper presents an overview of currently available methods for monitoring prestressing forces in prestressed concrete structure. Structural health monitoring has become an increasingly important tool for assessment of structural performance. Additionally, the value of the prestressing force represents an important parameter in prestressed concrete structures. Thus, several methods for monitoring prestress forces have emerged. This paper aims to consolidate the work performed in the area of prestressing force monitoring by presenting the most important advances and the directions for future research. The methods presented in this paper are based on indirect monitoring of the prestressing force through monitoring of another relevant parameter. They are divided into five general classes based on the relevant parameter they monitor:(a) vibration-based methods (based on acceleration), (b) impedance-based methods (based on electrical impedance), (c) acoustoelastic methods (based on wave velocity), (d) elasto-magnetic methods (based on magnetic permeability), and (e) strain-based methods (based on strain). The paper presents a table summarizing the comparison between the methods based on defined criteria.

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First-time demonstration of measuring concrete prestress levels with metal packaged fibre optic sensors

Cited by 19 publications

References 27 publications

Comparison of epoxy and braze-welded attachment methods for FBG strain gauges

Comparison of epoxy and braze-welded attachment methods for FBG strain gauges

Estimation of Tendon Force Distribution in Prestressed Concrete Girders Using Smart Strand

Monitoring of prestressing forces in prestressed concrete structures—An overview

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