scholarly journals Crack Detection of Reinforced Concrete Member Using Rayleigh-Based Distributed Optic Fiber Strain Sensing System

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Tingjin Liu ◽  
Honghao Huang ◽  
Yubing Yang
Keyword(s):  
Reinforced Concrete ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Crack Detection ◽  
Concrete Surface ◽  
Strain Sensing ◽  
Rc Structures ◽  
Strain Measurements ◽  
Space Resolution ◽  
Sensing System

Early detection of crack is critical for the maintenance of reinforced concrete (RC) structures. In this study, a distributed optical fiber (DOF) sensing system with Rayleigh Optical Frequency Domain Reflectometry (OFDR) technique was deployed to a member of RC structure in a full-scale laboratory experiment, which was subjected to a monotonic lateral load. With the aid of a high space resolution (up to 1 mm) and measurement accuracy (±1 micro strain) interrogator (OSI-S by Semicon), continuous strain measurements inside of the RC member are elaborately implemented. The result of crack detection by the analysis of the measured tensile strain profiles is in excellent agreement with the visually observable cracks mapped during the test. This confirms the ability of the optical fiber inside of RC members to capture cracks on concrete surface. Moreover, the recognition of crack orientation and depth is accomplished by comparing strain measurements of optical fibers installed at multiple locations.

Detection of Crack Travel and Opening of a Standard Notched Specimen Mode I Using Embedded FOS Device

2013 ◽  
Vol 442 ◽  
pp. 360-366 ◽  
Author(s):  
F.E. Utou ◽  
J. Gryzagoridis ◽  
B. Sun
Keyword(s):  
Optical Fiber ◽  
Light Beam ◽  
Fiber Optics ◽  
Optical Fibers ◽  
Crack Detection ◽  
Crack Opening ◽  
Engineering Structures ◽  
Notched Specimen ◽  
Sensing System ◽  
Total Failure

Crack detection and monitoring has become one of a focus center for the health monitoring of engineering structures under the influence of mechanical deformation.This paper discusses the detecting, tracking and monitoring mechanisms for the crack, by initiating a sensing system by using a standard notched specimen. Crack features such as magnitude of crack travel versus crack opening are displacement indicators that can vary due to the applied load on the normal line to the direction of the crack travel. More ever, the rate of the crack opening is considered to be proportional to the rate of the crack travel.Lines of three optical fibers of 125 nm are embedded and fixed at two ends and pass across the direction of the crack travel at an approximation of 2mm apart. The light of 2V from the source is passed through the optical fiber, across the crack tip. The crack opening forces the optical fiber to extend under tension, and hence the interruption of its diameter. This causes the decrease in the light intensity traveling through the fiber till the total failure of the fiber, to declare presence of crack. The embedded fiber optics on the specimen links the instrumentation optical system which permits the light beam throughput. Finally the converted light beam into voltage domain allowed us to closely analyze the crack tendency, and eventually be able to establish a model and sensor equation which governs the trend of the crack growth.

scholarly journals Truly Distributed Optical Fiber Sensors for Structural Health Monitoring: From the Telecommunication Optical Fiber Drawling Tower to Water Leakage Detection in Dikes and Concrete Structure Strain Monitoring

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Jean-Marie Henault ◽  
Gautier Moreau ◽  
Sylvain Blairon ◽  
Jean Salin ◽  
Jean-Robert Courivaud ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Brillouin Scattering ◽  
Optical Fiber Sensors ◽  
Leakage Detection ◽  
Strain Sensing ◽  
Water Leakage ◽  
Fiber Sensors ◽  
Practical Applications ◽  
Water Leakage Detection

Although optical fiber sensors have been developed for 30 years, there is a gap between lab experiments and field applications. This article focuses on specific methods developed to evaluate the whole sensing chain, with an emphasis on (i) commercially-available optoelectronic instruments and (ii) sensing cable. A number of additional considerations for a successful pairing of these two must be taken into account for successful field applications. These considerations are further developed within this article and illustrated with practical applications of water leakage detection in dikes and concrete structures monitoring, making use of distributed temperature and strain sensing based on Rayleigh, Raman, and Brillouin scattering in optical fibers. They include an adequate choice of working wavelengths, dedicated localization processes, choices of connector type, and further include a useful selection of traditional reference sensors to be installed nearby the optical fiber sensors, as well as temperature compensation in case of strain sensing.

scholarly journals Early Crack Detection of Reinforced Concrete Structure Using Embedded Sensors

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3879 ◽  
Author(s):  
Joyraj Chakraborty ◽  
Andrzej Katunin ◽  
Piotr Klikowicz ◽  
Marek Salamak
Keyword(s):  
Reinforced Concrete ◽  
Crack Detection ◽  
Structural Condition ◽  
Probability Of Detection ◽  
Embedded Sensors ◽  
Bending Test ◽  
Reinforced Concrete Structure ◽  
Destructive Testing ◽  
Rc Structures ◽  
Ultrasonic Signals

The damage in reinforced concrete (RC) structures can be induced either by the dynamic or static load. The inspection technologies available today have difficulty in detecting slowly progressive, locally limited damage, especially in hard-to-reach areas in the superstructure. The four-point bending test on the benchmark RC structure was used as a test of the quality and sensitivity of the embedded sensors. It allowed assessment of whether any cracking and propagation that occurs with the embedded sensors can be detected. Various methods are used for the analysis of the ultrasonic signals. By determining the feature from the ultrasonic signals, the changes in the whole structure are evaluated. The structural degradation of the RC benchmark structure was tested using various non-destructive testing methods to obtain a comprehensive decision about structural condition. It is shown that the ultrasonic sensors can detect a crack with a probability of detection of 100%, also before it is visible by the naked eye and other techniques, even if the damage is not in the direct path of the ultrasonic wave. The obtained results confirmed that early crack detection is possible using the developed methodology based on embedded and external sensors and advanced signal processing.

scholarly journals Performance of Rayleigh-Based Distributed Optical Fiber Sensors Bonded to Reinforcing Bars in Bending

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3125 ◽  
Author(s):  
Mattia Bado ◽  
Joan Casas ◽  
António Barrias
Keyword(s):  
Optical Fiber ◽  
Experimental Tests ◽  
Optical Fiber Sensors ◽  
Strain Sensing ◽  
Fiber Sensors ◽  
Rc Structures ◽  
Multiple Sensing ◽  
Load Types ◽  
Strain Threshold ◽  
Distributed Optical Fiber

Distributed Optical Fiber Sensors (DOFSs), thanks to their multiple sensing points, are ideal tools for the detection of deformations and cracking in reinforced concrete (RC) structures, crucial as a means to ensure the safety of infrastructures. Yet, beyond a certain point of most DOFS-monitored experimental tests, researchers have come across unrealistic readings of strain which prevent the extraction of further reliable data. The present paper outlines the results obtained through an experimental test aimed at inducing such anomalies to isolate and identify the physical cause of their origin. The understanding of such a phenomenon would enable DOFS to become a truly performant strain sensing technique. The test consists of gradually bending seven steel reinforcement bars with a bonded DOFS under different conditions such as different load types, bonding adhesives, bar sections and more. The results show the bonding adhesives having an influence on the DOFS performance but not on the rise of anomalies while the reasons triggering the latter are narrowed down from six to two, reaching a strain threshold and a change in structure’s deformative behavior. Further planned research will allow identification of the cause behind the rise of strain-reading anomalies.

Quantitative strain measurement and crack detection in RC structures using a truly distributed fiber optic sensing system

2012 ◽  
Vol 37 ◽  
pp. 916-923 ◽  
Author(s):  
J.-M. Henault ◽  
M. Quiertant ◽  
S. Delepine-Lesoille ◽  
J. Salin ◽  
G. Moreau ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Crack Detection ◽  
Fiber Optic ◽  
Rc Structures ◽  
Sensing System ◽  
Fiber Optic Sensing

scholarly journals A Multichannel Strain Measurement Technique for Nanomodified Smart Cement-Based Sensors in Reinforced Concrete Structures

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5633
Author(s):  
Andrea Meoni ◽  
Antonella D’Alessandro ◽  
Massimo Mancinelli ◽  
Filippo Ubertini
Keyword(s):  
Reinforced Concrete ◽  
Measurement Technique ◽  
Strain Measurement ◽  
Concrete Structures ◽  
Strain Sensing ◽  
Rc Structures ◽  
Multichannel Measurement ◽  
Sensing Technology ◽  
Technological Improvements ◽  
Detection And Localization

Nanomodified smart cement-based sensors are an emerging self-sensing technology for the structural health monitoring (SHM) of reinforced concrete (RC) structures. To date, several literature works demonstrated their strain-sensing capabilities, which make them suited for damage detection and localization. Despite the most recent technological improvements, a tailored measurement technique allowing feasible field implementations of smart cement-based sensors to concrete structures is still missing. In this regard, this paper proposes a multichannel measurement technique for retrieving strains from smart cement-based sensors embedded in RC structures using a distributed biphasic input. The experiments performed for its validation include the investigation on an RC beam with seven embedded sensors subjected to different types of static loading and a long-term monitoring application on an RC plate. Results demonstrate that the proposed technique is effective for retrieving time-stable simultaneous strain measurements from smart cement-based sensors, as well as for aiding the identification of the changes in their electrical outputs due to the influence of environmental effects variable over time. Accordingly, the proposed multichannel strain measurement technique represents a promising approach for performing feasible field implementations of smart cement-based sensors to concrete structures.

scholarly journals Distributed Optical Fiber Sensing Bonding Techniques Performance for Embedment inside Reinforced Concrete Structures

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5788
Author(s):  
Mattia Francesco Bado ◽  
Joan R. Casas ◽  
Alinda Dey ◽  
Carlos Gil Berrocal
Keyword(s):  
Reinforced Concrete ◽  
Optical Fiber ◽  
Protective Layer ◽  
Future Research ◽  
Rc Structures ◽  
Monitoring Tools ◽  
Externally Bonded ◽  
Optical Fiber Sensing ◽  
Distributed Optical Fiber ◽  
Bonding Technique

Distributed optical fiber sensors (DOFS) are modern-day cutting-edge monitoring tools that are quickly acquiring relevance in structural health monitoring engineering. Their most ambitious use is embedded inside plain or reinforced concrete (RC) structures with the scope of comprehending their inner-workings and the functioning of the concrete-reinforcement interaction. Yet, multiple studies have shown that the bonding technique with which the DOFS are bonded to the reinforcement bars has a significant role on the quality of the extracted strain data. Whilst this influence has been studied for externally bonded DOFS, it has not been done for embedded ones. The present article is set on performing such study by monitoring the strain measurement quality as sampled by DOFS bonded to multiple rebars with different techniques and adhesives. These instrumented rebars are used to produce differently sized RC ties later tested in tension. The discussion of the test outputs highlights the quasi-optimal performance of a DOFS/rebar bonding technique consisting of incising a groove in the rebar, positioning the DOFS inside it, bonding it with cyanoacrylate and later adding a protective layer of silicone. The resulting data is mostly noise-free and anomalies-free, yet still presents a newly diagnosed hitch that needs addressing in future research.

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