Characterization of concrete shrinkage induced strains in internally-restrained RC structures by distributed optical fiber sensing

Bado, Mattia Francesco; Casas, Joan R.; Dey, Alinda; Berrocal, Carlos Gil; Kaklauskas, Gintaris; Fernandez, Ignasi; Rempling, Rasmus

doi:10.1016/j.cemconcomp.2021.104058

Cited by 25 publications

(13 citation statements)

References 50 publications

(59 reference statements)

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“…Figure 8c illustrates the shrinkage strains following post-processing and the adjustment for temperature variation (the two lengths of interest and their mean value are only plotted inside the concrete). The smoothed strain profile is in agreement with findings from the literature [26]: a transition length is observed at both ends of the specimen, with shrinkage strains increasing toward the middle. This indicates the development of bond shear stresses in those parts.…”

Section: Dfos Adjustment For Shrinkage-induced Strainssupporting

confidence: 90%

“…To validate DFOS measurements, two approaches were followed: (i) comparison of direct results to local deformations of strain gauges [20,24]; (ii) comparison of integrated DFOS strain values to crack widths or deflections measured with LVDTs or DIC [19,22]. In a further application, shrinkage strains of the uncracked specimens were measured to account for their influence on the response of the reinforced concrete ties [25], and code predictions for shrinkage and creep strains were verified using DFOS [26]. Recently, Monsberger and Lienhart (2021) employed DFOS to extract the curvature and bending moment in structures by double integration of the obtained strains [27].…”

Section: Introductionmentioning

confidence: 99%

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Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Lemcherreq

Galkovski

Mata‐Falcón

et al. 2022

Sensors

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Distributed fibre optical sensing (DFOS) is increasingly used in civil engineering research. For reinforced concrete structures, almost continuous information concerning the deformations of embedded reinforcing bars can be obtained. This information enables the validation of basic and conventional assumptions in the design and modelling of reinforced concrete, particularly regarding the interaction of concrete and reinforcing bars. However, this relatively new technology conceals some difficulties, which may lead to erroneous interpretations. This paper (i) discusses the selection of sensing fibres for reinforced concrete instrumentation, accounting for strain gradients and local anomalies caused by stress concentrations due to the reinforcing bar ribs; (ii) describes suitable methods for sensor installation, strain acquisition and post-processing of the data, as well as determining and validating structurally relevant entities; and (iii) presents the results obtained by applying DFOS with these methods in a variety of experiments. The analysed experiments comprise a reinforced concrete tie, a pull-out test under cyclic load, and a flexural member in which the following mechanical relevant quantities are assessed: the initial strain state in reinforcing bars, normal and bond shear stresses, deflections as well as forces. These applications confirm the benefit of DFOS to better understand the bond behaviour, but also demonstrate that its application is intricate and the results may lead to erroneous conclusions unless evaluated meticulously.

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Section: Dfos Adjustment For Shrinkage-induced Strainssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Lemcherreq

Galkovski

Mata‐Falcón

et al. 2022

Sensors

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“…It has experienced a progressive abnormal deformation of the top and bottom slab, resulting in an abnormal deflection of the cantilever beams, which are mostly evident at the edge of the 59 m-long cantilever even several decades after its construction. This high sensitivity to creep and shrinkage phenomena is experienced by many other bridges of the same type, and has been investigated by several authors [23,35,36]. They suggest that the cause of such behaviour is the combination of creep phenomena, prestress tension losses, the huge difference between the top and the bottom slab in terms of thickness, the variation of the load condition during the construction phase, and maintenance works.…”

Section: Colle Isarco Viaduct Case Studymentioning

confidence: 89%

Designing a Structural Health Monitoring System Accounting for Temperature Compensation

et al. 2021

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Structural health monitoring is effective if it allows us to identify the condition state of a structure with an appropriate level of confidence. The estimation of the uncertainty of the condition state is relatively straightforward a posteriori, i.e., when monitoring data are available. However, monitoring observations are not available when designing a monitoring system; therefore, the expected uncertainty must be estimated beforehand. This paper proposes a framework to evaluate the effectiveness of a monitoring system accounting for temperature compensation. This method is applied to the design process of a structural health monitoring system for civil infrastructure. In particular, the focus is on the condition-state parameters representing the structural long-term response trend, e.g., due to creep and shrinkage effects, and the tension losses in prestressed concrete bridges. The result is a simple-to-use equation that estimates the expected uncertainty of a long-term response trend of temperature-compensated response measurements in the design phase. The equation shows that the condition-state uncertainty is affected by the measurement and model uncertainties, the start date and duration of the monitoring activity, and the sampling frequency. We validated our approach on a real-life case study: the Colle Isarco viaduct. We verified whether the pre-posterior estimation of expected uncertainty, performed with the experimented approach, is consistent with the real uncertainty estimated a posteriori based on the monitoring data.

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“…The latter embody the larger potential of the two, as extremely thin sensors (down to 125 le), can achieve completely distributed measurements (modern interrogation units can attain a spatial resolution of 0.63 mm) and with measurement frequencies of 250 Hz [23]. Recent applications of OFS in the civil and structural engineering field saw their use for the superficial [24] and embedded [25] monitoring of strains and cracks of RC structures, concrete shrinkage and shrinkage-induced compressive strains in embedded rebars [26], tension stiffening [27] and more [28]. Crucially, DOFS were also reported to be effective tools for the study of bond-slip occurring inside RC tension chords [3,[29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Validation of reinforced concrete bond stress–slip models through an analytical strain distribution comparison

2022

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The bond and slip between concrete and the reinforcement bars, cover a key role in the inter-material force transfer of Reinforced Concrete (RC) structures. In light of the lack of tools able to thoroughly inspect the inner workings of RC structures and to extract reliable bond stress values, modern bond stress–slip (Bond–slip) models are often inaccurate and in contradiction with each other. Considering the recent surge of novel hyper-performant strain sampling tools (Distributed Sensing for example), their application for the creation of novel and physically accurate Bond–slip models is just a matter of time. This being said, one of the main reasons behind the modern coexistence of multiple inaccurate and at times contradictory Bond–slip models is the absence of a tool that has allowed researchers to rapidly corroborate and calibrate their newly created models. To this end, the present article proposes such a Bond–slip validation tool for RC elements. This one is designed to extract reinforcement strain profiles at any given load level on the grounds of a specific bond–slip law and geometrical inputs. Said profile is then compared against an experimentally extracted one based on specimens with identical geometrical features. The performance of the validation tool is demonstrated through an application to six existing bond–slip models. Granted the proposal of validation tools is paramount for the future of the discussion on bond–slip modelling, stress-transfer analyses and serviceability of RC structures, the here proposed validation tool is a first significant step in that direction.

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Characterization of concrete shrinkage induced strains in internally-restrained RC structures by distributed optical fiber sensing

Cited by 25 publications

References 50 publications

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Designing a Structural Health Monitoring System Accounting for Temperature Compensation

Validation of reinforced concrete bond stress–slip models through an analytical strain distribution comparison

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