Field tests of fibre Bragg grating sensors incorporated into CFRP for railway bridge strengthening condition monitoring

Abstract

The EU is in the process of upgrading the national railway networks to meet the demands from highspeed passenger trains and heavy Freight traffic. This upgrade necessitates a review of the development and implementation of novel technologies to repair and strengthen the existing bridge structures and to improve their performance. This paper presents the evaluation results of the use of FBG strains sensors incorporated in CFRP (carbon fibre reinforcement polymer) rods and tubes as part of the methodology for monitoring the performance of the NSMR (near surface mounted reinforcement) which is an essential part of the repair and strengthening of bridges. In addition, a new method has been tested for the first time using CFRP tubes which calls for the drilling of holes instead of sawing grooves in the installation process. The paper discusses in some detail the strengthening mechanism, FBG sensor implementation and the electronic system used to interrogate the FBG sensors. The results obtained from the monitoring show that FBG sensors can be integrated into CFRP and that reliable measurements can be made. However, in this particular project, the strain loading is very moderate so consequently the strain levels are in the elastic regime.

Strain Measurement Using Embedded Fiber Bragg Grating Sensors Inside an Anchored Carbon Fiber Polymer Reinforcement Prestressing Rod for Structural Monitoring

“…This was similar to that used by the authors previously [11], [12], where the array of sensors was illuminated by light from a broadband source and detected using an optical spectrometer containing a Fabry-Perot tuneable filter that scans the narrow band light from the source and sweeps over wavelength of the gratings in the array. Such an approach allows for the identification of the characteristic wavelength change with strain of each of the sensors reflecting back a signal-the Gaussian peak of the signal is used to indicate the wavelength.…”

Wireless Sensor Networks: Toward Smarter Railway Stations

“…Moreover, it used in combination with strain gauges [39,40]. Fibre optical sensors aid to measure temperature, strain, and acceleration [41,42]. Gyroscopes can be used to measure vehicles' angular velocity around axes in the train.…”

Textile carbon reinforcement structures with integrated optical fibre sensors designed for SHM applications

“…The data thus obtained can then be used to predict potential structural failure, so that appropriate maintenance can be scheduled to address the economic benefits and ethical need for safe and sustainable infrastructures. This also goes hand in hand with the need to ensure that appropriate strengthening mechanisms of such structures are in place -the most recent advance being the utilisation of carbon fibre reinforcement polymer (CFRP) to strengthen concrete structures [2].…”

“…The usual method of utilising FOS for the purpose is to "glue", using for example epoxy, a network of sensors to the structure in question and monitor any variation in applied strain using interferometric techniques [2]. This technique, therefore, relies on the glue, that is used, being able to fully transfer the strain to the sensing element.…”