Improving Distributed Fiber-Optic Sensor Measures by Digital Image Correlation: Two-Stage Structural Health Monitoring

This paper deals with the integrated use of distributed fiber-optic sensors and digital image correlation techniques to develop a two-stage monitoring method for damage detection, localization, and quantification. The proposed methodology was applied in the laboratory on reinforced concrete beam specimens and is suitable for further field developments in concrete structures of large dimensions. The first stage is based on distributed strain monitoring through Brillouin scattering-based fiber-optic sensors to detect and locate potential damage zones within the entire structure, while the second focuses on verification of the critical regions identified by the optical-fiber sensor using the digital image correlation technique

An optical fibre sensor for dynamic deformation measurements based on the intensity modulation of a low-coherence source

An optical fibre sensing technique for the measurement of dynamic deformations using a Michelson interferometer is reported. The method applied to interferometers with an initial path unbalance of around 1 cm is based on the rf intensity modulation of a low-coherence source. A large measurement range of 1 cm is intrinsic to the method and with an adequate demodulation process sensitivity better than 10 μm is obtained. This novel approach allows for measuring dynamic deformations with a bandwidth up to 100 Hz

Structural health monitoring of in-service tunnels

This work presents an overview of some of the most promising technologies for the structural health monitoring (SHM) of in-service tunnels. The common goal of damage or unusual behaviour detection is best pursued by an integrated approach based on the concurrent deployment of multiple technologies. Typically, traditional SHM systems are installed in problematic or special areas of the tunnels, giving information on conditions and helping manage maintenance. However, these methodologies often have the drawbacks of forcing the interruption of traffic for SHM system installation and monitoring only selected portions. Alternative solutions that would make it possible to keep the tunnel in normal operation and/or to analyse the entire infrastructure development through successive and continuous scanning stages, would be beneficial. In this paper, the authors will briefly review some traditional monitoring technologies for tunnels. Furthermore, the work is aimed at identifying alternative solutions, limiting or avoiding traffic interruptions

Monitoring of large structure using distributed Brillouin fibre sensing

On-site distributed measurements using a sensor based on stimulated Brillouin scattering are presented. Long fibre length can be used, so that a dense 2D or 3D measurement of strain or temperature can be obtained in large structure

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

Fiber Optic Sensing for Innovative Oil and Gas Production and Transport Systems

Fiber optic sensing presents unique features that have no match in conventional sensing techniques. The ability to measure temperatures and strain at thousands of points along a single fiber is particularly interesting for the monitoring of elongated structures such as pipelines, flow lines, oil wells and coiled tubing. Distributed sensing systems based on Brillouin and Raman scattering are used for example to detect pipeline leakages, verify pipeline operational parameters, prevent failure of pipelines installed in landslide areas, optimize oil production from wells and detect hot-spots in high-power cables. Point sensors based on Interferometric and FBG setups are also effective tools to assess the static and dynamic response of structures such as offshore platforms and risers.This contribution presents different applications of distributed and point sensors to innovative oil and gas structures such as composite coiled tubing, high-pressure composite gas pipeline and deepwater risers