Review: optical fiber sensors for civil engineering applications

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 sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-of-the-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry

Dynamic structural health monitoring of slender structures using optical sensors

In this paper we summarize the research activities at the Instituto de Telecomunicações—Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures’ natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior

Comparison between point and long-gage FBG-based strain sensors during a railway bridge load test

[EN] Strain is a key parameter in laboratory and bridge load testing. The selection of a strain sensor depends on several factors, including the aim of the test and the specimen material. The application of the right sensor is vital to obtain accurate readings, especially in the case of heterogeneous materials such as concrete. This paper focuses on long‐gage and point fiber Bragg grating‐based strain sensors and their possible applications on concrete elements. First, strain sensors are described, after which long‐gage and point fiber Bragg grating strain sensors are compared in a concrete specimen test, a concrete column test and static and dynamic load tests on a concrete railway bridge. Results show that although it is advisable to use long‐gage sensors when monitoring heterogeneous materials, there are some particular cases were both sensors type can provide accurate strain measurements.Torres Górriz, B.; Rinaudo, P.; Calderón García, PA. (2017). Comparison between point and long-gage FBG-based strain sensors during a railway bridge load test. STRAIN. 4:1-14. doi:10.1111/str.12230S1144Calderón, P. A., & Glisic, B. (2012). Influence of mechanical and geometrical properties of embedded long-gauge strain sensors on the accuracy of strain measurement. Measurement Science and Technology, 23(6), 065604. doi:10.1088/0957-0233/23/6/065604Glišić, B., & Inaudi, D. (2007). Fibre Optic Methods for Structural Health Monitoring. doi:10.1002/9780470517819Kissinger, T., Charrett, T. O. H., & Tatam, R. P. (2013). Fibre segment interferometry using code-division multiplexed optical signal processing for strain sensing applications. Measurement Science and Technology, 24(9), 094011. doi:10.1088/0957-0233/24/9/094011Leite, L., Bonet, J. L., Pallarés, L., Miguel, P. F., & Fernández-Prada, M. A. (2013). Experimental research on high strength concrete slender columns subjected to compression and uniaxial bending with unequal eccentricities at the ends. Engineering Structures, 48, 220-232. doi:10.1016/j.engstruct.2012.07.039Leite, L., Bonet, J. L., Pallarés, L., Miguel, P. F., & Fernandez-Prada, M. A. (2012). Behavior of RC slender columns under unequal eccentricities and skew angle loads at the ends. Engineering Structures, 40, 254-266. doi:10.1016/j.engstruct.2012.02.017Garzón-Roca, J., Ruiz-Pinilla, J., Adam, J. M., & Calderón, P. A. (2011). An experimental study on steel-caged RC columns subjected to axial force and bending moment. Engineering Structures, 33(2), 580-590. doi:10.1016/j.engstruct.2010.11.016Realfonzo, R., Napoli, A., & Pinilla, J. G. R. (2014). Cyclic behavior of RC beam-column joints strengthened with FRP systems. Construction and Building Materials, 54, 282-297. doi:10.1016/j.conbuildmat.2013.12.043Torres, B., Payá-Zaforteza, I., Calderón, P. A., & Adam, J. M. (2011). Analysis of the strain transfer in a new FBG sensor for Structural Health Monitoring. Engineering Structures, 33(2), 539-548. doi:10.1016/j.engstruct.2010.11.012www.fos-s.bewww.smartec.chwww.alava-ing.eshttp://www.micronoptics.comB. Glišić Inaudi D J.M. Lau 7th International Conference on Multi-Purpose High-Rise Towers and Tall Buildings (IFHS) 2005Rinaudo, P., Torres, B., Paya-Zaforteza, I., Calderón, P. A., & Sales, S. (2015). Evaluation of new regenerated fiber Bragg grating high-temperature sensors in an ISO 834 fire test. Fire Safety Journal, 71, 332-339. doi:10.1016/j.firesaf.2014.11.024Moyo, P., Brownjohn, J. M. W., Suresh, R., & Tjin, S. C. (2005). Development of fiber Bragg grating sensors for monitoring civil infrastructure. Engineering Structures, 27(12), 1828-1834. doi:10.1016/j.engstruct.2005.04.023B. Torres Górriz Definición de las pautas y condiciones de monitorización, encapsulado y fijación de sensores de fibra óptica para la medida de deformación y temperatura en estructuras. Ed. UPV 2012Kinet, D., Mégret, P., Goossen, K., Qiu, L., Heider, D., & Caucheteur, C. (2014). Fiber Bragg Grating Sensors toward Structural Health Monitoring in Composite Materials: Challenges and Solutions. Sensors, 14(4), 7394-7419. doi:10.3390/s14040739

Experimental and numerical analysis of a hybrid FBG long gauge sensor for structural health monitoring

This paper presents a new long gauge sensor for structural health monitoring based on the use of Fiber Bragg gratings. The proposed sensor has the advantage over existing sensors that it does not require prestressing of the optical fiber. The development consisted of numerical studies complemented by experimental tests to analyze: (1) the strain transfer between the sensor and the host structure; (2) the in!uence of sensor axial stiffness on the structural behavior of the host structure; (3) the in!uence of the mechanical properties of the adhesive used to fix the sensor and (4) the failure modes of the sensor (buckling and shear stress of sensor anchors).This work was made possible by the support from the Universitat Politecnica de Valencia, the Spanish Ministry for Science and Innovation (Research Project BIA2011-27104) and the Spanish Ministry of Public Works (Project Sopromac P41/08).Torres Górriz, B.; Calderón García, PA.; Paya-Zaforteza, I.; Sales Maicas, S. (2014). Experimental and numerical analysis of a hybrid FBG long gauge sensor for structural health monitoring. Measurement Science and Technology. 25:1-15. https://doi.org/10.1088/0957-0233/25/12/125107S11525Glišić, B., & Inaudi, D. (2007). Fibre Optic Methods for Structural Health Monitoring. doi:10.1002/9780470517819Kissinger, T., Charrett, T. O. H., & Tatam, R. P. (2013). Fibre segment interferometry using code-division multiplexed optical signal processing for strain sensing applications. Measurement Science and Technology, 24(9), 094011. doi:10.1088/0957-0233/24/9/094011Abang, A., & Webb, D. J. (2013). Effects of annealing, pre-tension and mounting on the hysteresis of polymer strain sensors. Measurement Science and Technology, 25(1), 015102. doi:10.1088/0957-0233/25/1/015102Calderón, P. A., & Glisic, B. (2012). Influence of mechanical and geometrical properties of embedded long-gauge strain sensors on the accuracy of strain measurement. Measurement Science and Technology, 23(6), 065604. doi:10.1088/0957-0233/23/6/065604Torres, B., Payá-Zaforteza, I., Calderón, P. A., & Adam, J. M. (2011). Analysis of the strain transfer in a new FBG sensor for Structural Health Monitoring. Engineering Structures, 33(2), 539-548. doi:10.1016/j.engstruct.2010.11.012Majumder, M., Gangopadhyay, T. K., Chakraborty, A. K., Dasgupta, K., & Bhattacharya, D. K. (2008). Fibre Bragg gratings in structural health monitoring—Present status and applications. Sensors and Actuators A: Physical, 147(1), 150-164. doi:10.1016/j.sna.2008.04.008Li, D. (2006). Strain transferring analysis of fiber Bragg grating sensors. Optical Engineering, 45(2), 024402. doi:10.1117/1.2173659Moyo, P., Brownjohn, J. M. W., Suresh, R., & Tjin, S. C. (2005). Development of fiber Bragg grating sensors for monitoring civil infrastructure. Engineering Structures, 27(12), 1828-1834. doi:10.1016/j.engstruct.2005.04.023Leng, J. S., Winter, D., Barnes, R. A., Mays, G. C., & Fernando, G. F. (2006). Structural health monitoring of concrete cylinders using protected fibre optic sensors. Smart Materials and Structures, 15(2), 302-308. doi:10.1088/0964-1726/15/2/009Kesavan, K., Ravisankar, K., Parivallal, S., Sreeshylam, P., & Sridhar, S. (2010). Experimental studies on fiber optic sensors embedded in concrete. Measurement, 43(2), 157-163. doi:10.1016/j.measurement.2009.08.010Hill, K. O., & Meltz, G. (1997). Fiber Bragg grating technology fundamentals and overview. Journal of Lightwave Technology, 15(8), 1263-1276. doi:10.1109/50.618320Chung, W., & Kang, D. (2008). Full-scale test of a concrete box girder using FBG sensing system. Engineering Structures, 30(3), 643-652. doi:10.1016/j.engstruct.2007.05.003Adam, J. M., Brencich, A., Hughes, T. G., & Jefferson, T. (2010). Micromodelling of eccentrically loaded brickwork: Study of masonry wallettes. Engineering Structures, 32(5), 1244-1251. doi:10.1016/j.engstruct.2009.12.05

Fiber Optic Sensors Embedded in Textile-Reinforced Concrete for Smart Structural Health Monitoring: A Review

The last decade has seen rapid developments in the areas of carbon fiber technology, additive manufacturing technology, sensor engineering, i.e., wearables, and new structural reinforcement techniques. These developments, although from different areas, have collectively paved way for concrete structures with non-corrosive reinforcement and in-built sensors. Therefore, the purpose of this effort is to bridge the gap between civil engineering and sensor engineering communities through an overview on the up-to-date technological advances in both sectors, with a special focus on textile reinforced concrete embedded with fiber optic sensors. The introduction section highlights the importance of reducing the carbon footprint resulting from the building industry and how this could be effectively achieved by the use of state-of-the-art reinforcement techniques. Added to these benefits would be the implementations on infrastructure monitoring for the safe operation of structures through their entire lifespan by utilizing sensors, specifically, fiber optic sensors. The paper presents an extensive description on fiber optic sensor engineering that enables the incorporation of sensors into the reinforcement mechanism of a structure at its manufacturing stage, enabling effective monitoring and a wider range of capabilities when compared to conventional means of structural health monitoring. In future, these developments, when combined with artificial intelligence concepts, will lead to distributed sensor networks for smart monitoring applications, particularly enabling such distributed networks to be implemented/embedded at their manufacturing stage

Concrete fatigue experiment for sensor prototyping and validation of industrial SHM trials

In this paper, preliminary results from a concrete fatigue experiment using a custom built machine are demonstrated. A pre-cracked concrete member is instrumented with bespoke metallic-bonded and epoxy-bonded fiber Bragg grating (FBG) displacement sensors, retrofitted over the crack. Fatigue loading is applied to the beam, with cycle magnitudes replicating results from a previous industrial trial concerning structural health monitoring (SHM) of a wind turbine foundation. Results are compared to an FEM model for verification. The new metallic-bonded crack displacement sensor design is compared in performance with the traditional epoxy-bonded design. Both sensors were sufficiently resilient under dynamic loading to successfully undergo 105 cycle fatigue test. The sensors display a linear relationship with respect to one another; however, from the initial thermal characterization of the devices between 20 and 65 °C, the epoxy-bonded sensor exhibited considerable drift with every subsequent temperature cycle while the metallic-bonded construction was stable within the experimental error. The set up can be used over a long term to validate in situ results from distributed SHM sensors and for initial testing of sensors and data analytics strategies prior to any future field installations

A progressive collapse evaluation of steel structures in high temperature environment with optical fiber sensors

In the process of a progressive failure of steel structures in a post-earthquake fire, real-time assessment and prediction of structural behaviors are of paramount significance to an emergency evacuation and rescue effort. However, existing measurement technologies cannot provide the needed critical data such as large strains at high temperature. To bridge this gap, a novel optical fiber sensor network and an adaptive multi-scale finite element model (FEM) are proposed and developed in this study. The sensor network consists of long period fiber gratings (LPFG) sensors and extrinsic Fabry-Perot interferometer (EFPI) sensors or their integration. Each sensor is designed with a three-tier structure for an accurate and reliable measurement of large strains and for ease of installation. To maintain a balance between the total cost of computation and instrumentation and the accuracy in numerical simulation, a structure is divided into representative/critical components instrumented densely and the remaining components simulated computationally. The critical components and the remaining were modeled in different scales with fiber elements and beam/plate elements, respectively, so that the material behavior and load information measured from the critical components are representative to the remaining components and can be used to update the temperature distribution of the structure in real time. Sensitivity studies on the number of sensors and the initial selection of an updating temperature parameter were conducted. Both the sensor network and the FEM were validated with laboratory tests of a single-bay, one-story steel frame under simulated post-earthquake fire conditions. The validated FEM was applied to a two-bay, four-story steel building under the 1995 Kobe earthquake excitations. Based on extensive tests and analyses, the proposed sensor can measure a strain of 12% at as high as 800⁰C (1472⁰F) in temperature. Within the application range, the LPFG wavelength and the EFPI gap change linearly with the applied strain and temperature. The proposed updating criterion and algorithm in the adaptive FEM are proven to be effective. The number of sensors is sufficient in engineering applications as long as the sensors can adequately represent the material behavior of the instrumented components. The predicted structural behavior is unaffected by any change in a low temperature range and thus insensitive to the initial selection of the updating parameter --Abstract, page iii

Development of a high-sensitivity and adjustable FBG strain sensor for structural monitoring

In this paper, a new fiber Bragg grating (FBG ) strain sensor with adjustable sensitivity is invented. The sensitivity adjustment, strain sensing, and temperature compensation principles of the sensor and the corresponding formulae are developed. The prototype sensor specimen is developed, and a series of tests are performed to investigate its strain sensitivity and temperature compensation characteristics. The results show that the strain sensitivity of the sensor can be adjusted effectively by the correspondent L/LFBG parameter, with an acceptable discrepancy within ± 5% of the theoretical value. The linearity, repeatability, and hysteresis were analyzed, and the errors were 0.98%, 1.15%, and 0.09%, respectively, with excellent performance. When the temperature difference was 20°C, through temperature compensation calibration, the error between the monitored strain and the actual strain was within 5% after temperature compensation correction, showing that this new type of FBG strain sensor can meet the strain monitoring needs of various engineering structures and provide reliable data acquisition

D5.1 SHM digital twin requirements for residential, industrial buildings and bridges

This deliverable presents a report of the needs for structural control on buildings (initial imperfections, deflections at service, stability, rheology) and on bridges (vibrations, modal shapes, deflections, stresses) based on state-of-the-art image-based and sensor-based techniques. To this end, the deliverable identifies and describes strategies that encompass state-of-the-art instrumentation and control for infrastructures (SHM technologies).Objectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement EconòmicObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPreprin