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Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee “Optical fiber sensors for civil engineering applications”, different kinds of sensin...
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... Fiber optic sensors have the advantages of compact structure, high sensitivity, and strong resistance to electromagnetic interference. They can be widely used in aerospace, petroleum, chemical, and other industrial fields for the measurement of physical parameters such as temperature, pressure, and strain [1] . Currently, commonly used fiber optic sensors include fiber Bragg gratings (FBGs) [2] , Fabry-Perot interferometers (FPIs) [3] , long-period fiber gratings (LPFGs) [4] , and Mach-Zehnder interferometers (MZIs) [5] . ...
... Recently, Pitawala et al. (2022) demonstrated the application of distributed fibre optic sensors to foamed bitumen stabilised pavement beams in order to characterise their flexural behaviour in the laboratory while using a technique based on Rayleigh scattering as in the present study. A broader picture about recent applications of fibre optic sensors in pavements is provided within the study of De Maeijer et al. (2019), more general applications in civil engineering are reported e.g. in Leung et al. (2015) and an overview of the various fibre optic sensor technologies is provided e.g. by Hartog (2017) or Thévenaz (2011). ...
Understanding the in-situ structural behaviour of pavements plays an important role in road engineering. Hence, various measurement methods were developed in the past to get an insight into the response of roads to traffic loading. In the present study, distributed fibre optic strain sensors were embedded into a hot mix asphalt pavement. The sensors were used for strain measurements with high spatial resolution in order to assess its feasibility to gain the continuous strain distribution in the pavement under short-term static loading. In addition, the loading process was measured with high temporal resolution, indicating that-using shorter sensor lengths-vehicle passages could also be studied. The strain distributions gathered with this type of sensor were compared to the results of a simple finite element model and the effect of applying various sensor cables. In addition, new opportunities provided by distributed fibre optic sensors in road engineering are discussed. ARTICLE HISTORY
... Over the years, many technologies have been developed to characterize damages in concrete infrastructures. These can be classified based on the sensing principle utilized: stress waves [1,2], electrical properties [3,4], optical fibers [5,6], or digital image correlation (DIC) [7]. Among these techniques, the vision-based technique is considered apt because of its simple implementation as well as direct and easy result interpretation. ...
In this paper, we introduce SHSnet, an advanced deep learning model designed for the efficient end-to-end segmentation of complex cracks, including thin, tortuous, and densely distributed ones. SHSnet features a non-uniform attention mechanism, a large receptive field, and boundary refinement to enhance segmentation performance while maintaining computational efficiency. To further optimize the model’s learning capability with highly imbalanced datasets, we employ a loss function (LP) based on the focal Tversky function. SHSnet shows very high performance, with values of 0.85, 0.83, 0.81, and 0.84 for precision, recall, intersection over union (IOU), and F-score, respectively. It achieves this with 10× fewer parameters than other models in the literature. Complementing SHSnet, we also present the post-processing unit (PPU), which analyzes crack morphological parameters through fracture mechanics and geometric properties. The PPU generates scanning lines to accurately compute these parameters, ensuring reliable results. The PPU shows a relative error of 0.4%, 1.2%, and 5.6% for crack number, length, and width, respectively. The methodology was benchmarked on complex ECC crack datasets as well as on multiple online datasets. In both of these cases, our results confirm that SHSnet consistently delivers superior performance and efficiency across various scenarios as compared to the methods in the literature.
... As the field continues to evolve, interdisciplinary collaborations between engineering, optics, materials science, and geology are likely to drive further innovations in research and practical implementations. In the past 35 years, DFOS technology has been applied to the monitoring of pipelines, slopes, tunnels, foundations, and other engineering projects [72,73]. Meanwhile, relevant model tests and feasibility studies have also been continuously carried out [74][75][76]. ...
DFOS (distributed fiber-optic sensing) technology has shown the potential to increase the accuracy of measurement after years of development and experimenting in geoengineering monitoring. To better understand the development of DFOS technology and its contribution to geoengineering, an objective and data-driven review of the development process of DFOS technology in construction was completed. The review was accomplished by using text mining methods on the Web of Science, covering a wide range of relevant data, including 3970 articles from 1989 to 2023. The results indicate that DFOS technology research demonstrates the typical characteristics of multi-author, multi-country, and multi-institution collaborations, spanning various research fields. Over the past 35 years, the number of published articles has exhibited exponential growth, with China making significant contributions and leading in terms of its total publication growth rate, which has been higher than that of the United States since 2016. In the analysis of author keywords, emerging technologies, such as machine learning and distributed acoustic sensing, have garnered attention. The findings contribute to a comprehensive understanding of the development, impact, and future trends of DFOS technology in geotechnical engineering, offering valuable insights for researchers, scholars, and students in the field and inspiring new approaches for research methods in this domain.
... [3][4][5][6][7][8][9]. Fiber sensors can be implemented to monitor structures, pipelines, oil and gas reservoirs, wellbores, as well as temperature changes in dams and permafrost [4,[9][10][11][12]. They can be applied to rail-track monitoring, detection of earthquakes and water swells, and load displacement monitoring in mines [4,10,[12][13][14][15]. ...
... Fiber sensors can be implemented to monitor structures, pipelines, oil and gas reservoirs, wellbores, as well as temperature changes in dams and permafrost [4,[9][10][11][12]. They can be applied to rail-track monitoring, detection of earthquakes and water swells, and load displacement monitoring in mines [4,10,[12][13][14][15]. Thus, fiber sensors can play a role in preventing and mitigating the social, economic, and environmental costs of accidents and natural disasters. ...
We demonstrate an optical fiber sensor that uses the orbital angular momentum of light in a polarization maintaining fiber to act as a temperature and force sensor. The polarization of the input light is shown to greatly affect the sensitivity of the sensor. In addition, we show how our sensor can be used to resolve the direction and magnitude of a force applied to a fiber.
... For instance, the use of electromagnetic equipment plays a crucial role in assessing the performance of concrete structures equipped with sensors and actuators [36,37]. These systems commonly incorporate smart materials such as memory alloys [38][39][40], piezoelectric materials [41][42][43], and optical fibers [44][45][46][47], marking an important step towards the development of smart materials. ...
This research experimentally assessed the compressive strength enhancement of 7- and 28-day concrete specimens with up to 20 % silica sand and micro silica under an alternating magnetic field up to 1 Tesla. By applying magnetic fields to hardened concrete, properties can be tailored to specific needs, thus lowering cement usage and CO2 production. It was found that adding 10 % micro silica reduced the compressive strength at 7 and 28 days, while using 10 % silica sand and 5 % micro silica increased the compressive strength by 14.55 % and 7.79 %, respectively. Exposing specimens to a magnetic field increased compressive strength, with improvements up to 60.36 % for 7-day and 48.02 % for 28-day concrete at 1 T. Incorporating silica sand and micro silica in concrete positively impacts compressive strength under a magnetic field. Silica sand enhances compatibility with additives, improving strength. However, substituting 10 % of cement with micro silica reduces strength due to decreased aggregate adherence. 7-day specimens are more susceptible to magnetic fields than 28-day specimens due to lower displacement in younger samples. This innovative method enables controlled material behavior under magnetic influence. It aims to reduce cement usage while compensating for strength reduction caused by micro silica substitution. The study also determines the minimum magnetic field needed to counteract strength decrease; the aspects which not previously explored.
... More significantly, although two spans of cables (H-and Tcables) were assumed to embed parallel with the help of cable guides, a slight variance in the temperature change was observed (a case of 2.4 W/m in Fig. 9 as an example). Leung et al. (2015) also stated that despite the installation of numerous parallel fibres inside the structure, it is challenging to maintain uniformity in the measurements. While the OFDR sensing method promises high accuracy and repeatability, actual measurements (such as strain and temperature changes) often exhibit nonsmooth curves due to environmental conditions and irregularities in sensor placement. ...
This study demonstrates the ability of the Rayleigh-based phase-noise compensated optical frequency-domain reflectometry (PNC-OFDR) sensing method to monitor the distributed temperature field with an ultra-short data acquisition period of 2 ms, a spatial resolution of 2 cm, and a temperature resolution of 0.1 °C. A heating cable (H-cable) was embedded within a cylindrical concrete mortar specimen and subjected to various heating powers. A sensing optical cable (temperature measurement cable) was placed adjacent to the H-cable to monitor the temperature distribution continuously. Two water-holding boxes were installed along the specimen at two positions to retain water. The study’s results indicated that the PNC-OFDR technique demonstrated a high sensitivity to even small temperature changes, enabling it to pinpoint water locations at two distinct points accurately. The research determined the minimal heating power required to successfully locate the water positions. The magnitude of the heating power exerted a significant impact on the temperature change. Three distinct phases of temperature increment were observed for a given heating period: rapid, fast, and gentle increase. The insights gained from this study have the potential to be applied in natural fields, allowing for the detection of groundwater and seepage phenomena in vulnerable slopes.
... Some of the advantages of optical fiber are resistance to electromagnetic field interference, small size and light weight, does not cause sparks against corrosion. Many researches on the use of optical fiber sensors as crack detection have been carried out, such as crack detection using Optical Time Domain Reflectometer (OTDR) techniques [8], Brillouin Optical Time Domain Reflectometer (BOTDR) [9,10] and Brillouin Optical Frequency Domain Analysis (BOFDA) [11,12]. Other studies by varying the angle of inclination of fiber optic embedded in concrete [13] and utilizing the bending loss in fiber optic [14,15,16]. ...
... Optical fiber sensors are a diverse group, broadly categorized into three types: point, multipoint, and distributed (Brogan & Walt, 2005;Hartog, 2017;Lee, 2003;Leung et al., 2015;Motil et al., 2016). Point sensors are limited to sensing at a single location on the optical fiber, typically where the fiber Bragg grating (FBG) is inscribed or at the optical fiber's end face. ...
... Distributed fiber optic sensor systems (DFOS) offer interesting possibilities for strain and temperature measurement, especially in concrete construction [1][2][3][4][5]. There are already isolated applications in the field of Structural Health Monitoring (SHM) of structural and civil engineering, geotechnics or in special heavy construction [6][7][8][9][10][11][12][13][14][15][16][17]. These measurement systems have enormous potential, particularly in terms of sustainable long-term use of structures, but also in terms of improving civil safety by monitoring the structural health [18,19]. ...
Distributed fiber optic strain measurement techniques have become increasingly important in recent years, especially in the field of structural health monitoring of reinforced concrete structures. Numerous publications show the various monitoring possibilities from bridges to special heavy structures. The present study is intended to demonstrate the possibilities, but also the challenges, of distributed fiber optic strain measurement in reinforced concrete structures. For this purpose, concrete beams for 3-point bending tests were equipped with optical fibers on the reinforcement and concrete surface as well as in the concrete matrix in order to record the strains in the compression and tension zone. In parallel, an analytical approach based on the maximum strains in the uncracked and cracked states was performed using the Eurocode 2 interpolation coefficient. In principle, the structural design correlates with the measured values, but the strains are underestimated, especially in the cracked zone. During load increase, structural distortions in the compression zone affected the strain signal, making reliable evaluation in this zone difficult. The information content of distributed fiber optic strain measurement in reinforced concrete structures can offer tremendous opportunities. Future research should consider all aspects of the bond, sensor selection and positioning. In addition, there is a lack of information on the long-term stability of the joint and the fiber coating, as well as the effects of dynamic loading.
