Monitoring of new and existing infrastructures by embedded sensors to assess the indicators required for their sustainable management – SCaNING

The project SCaNING is organized into five transversal working packages (see the organizational scheme). WP1 is devoted to the coordination and valorisation of the project.

WP2 aim is the embedded measurement systems development and is led by LMDC and Univ. Eiffel whose researchers are specialists either in electromagnetic NDE or in ultrasonic NDE. The objectives will be adapted according to the degree of method development. But the main targets remain common:
• design the measuring systems and test them on laboratory specimens;
• implement them in large full-scale mockups;
• compare the surface measurements with those by embedded systems;
• model electromagnetic, electrical and acoustic field properties to integrate these data into combination processes.
Thus, the embedded sensor designed by consortium members [Badr et al. 2019] for resistivity measurement will be used. Meanwhile, capacitive probes and low-cost piezoelectric sensor systems will be designed and tested numerically, then calibrated in concrete specimens. The whole measuring chain (signal generation, reception and processing) will be also validated in concrete demonstrators of WP5.

WP3 aim is the extraction of observables decoupled from influencing factors. WP3 is led by LMA and Univ. Eiffel, interested in SHM and decoupling temperature effects from on-site mechanical recordings. The identification of influencing factors, the needed complementary monitoring and the data processing ensuing from SHM state-of-the-art will be implemented for improving the observable quality.

WP4 aims at improving the indicator assessment by processing observables; it is led by I2M and LMA whose researchers develop artificial intelligence algorithms or use data-processing methodologies. A user-friendly combination method, including calibration and considering uncertainties, will be developed to retrieve the indicators from multi-physics observables. A benchmark of the available tools including data fusion, open source software and the new multi-physics combination will enable to evaluate the added value for durability indicator assessment.

WP5 aims at building a demonstrator consisting of a full-scale instrumented structure linked to an open data web platform and smaller instrumented blocks; WP5 is led by Univ. Eiffel and Andra, who manage new and old reinforced concrete structures. The large demonstrator corresponds to newly built reinforced concrete structures, with sensors integrated into the fresh concrete. The blocks instrumented by the same sensors put in reservations and sealed a few months later correspond to the old structures. After validation, each type of embedded sensor systems will be implemented in the mock-up, related to their specific dataloggers or computer card PEGASE3 communicating by Wifi with the supervising platform STOCO. The last central web platform will enable each researcher of the project to remotely configure and collect in live all measurements and data process them.

In October 2021, two PhD students began the design of embedded electromagnetic and ultrasonic sensor systems, with both numerical parametric studies and experimental testings. The validation in small concrete specimens is in progress. The metrological and statistical characterization is also in progress.

A set of demonstrators will be instrumented and subjected to different environmental conditions: the reinforced concrete mock-up for the sensors embedded in fresh concrete and the blocks either for statistical analysis of calibration and corrections or for sensors placed inside reservations several months after casting. The casting of the demonstrators is scheduled for the first quarter of 2023.

After a state-of-the-art about the “cleaning” methods for correcting the data from undesirable effects, such as temperature, used for Structural Health Monitoring, an experimental program to evaluate the temperature effect on the small blocks has been designed and scheduled. The correction of the observables from undesirable effects will thus be determined.

The system for monitoring, storage and communication of the data collected by the sensors has been also developed in parallel. Depending on the sensor systems, the monitoring and data collection is ensured by either specific dataloggers or Pegase3 cards close to the demonstrators. The Supervising solution is ensured by the generic STOCO software which is configured to receive data from these different local dataloggers. The main functions that STOCO will shortly bring are:
• remote configuration of the different sensors (sampling frequency, thresholds adjusting…);
• data recording in a Big Data database (STOCO uses MongoDB database that is a non-indexed database dedicated to huge and long amount of data collection);
• data export in user-need formats to enable and accelerate the comparison between various monitoring methodologies.

Data visualization by graphics and data processing inside STOCO platform are still in development. Note that the electronic cards design, the Pegase3 programming and STOCO functions have been developed mainly in 2022 thanks to Quentin Bossard, research engineer whose contribution was additionally supported by the Pays de la Loire Region in agreement with the ANR.

The demonstrator building is our next most important challenge in mars 2023. Then, the further objectives of the project ANR-SCaNING will be investigated such as temperature corrections, calibration, development of combination method, benchmark on the indicator extraction and evaluation of the designed methodologies.

Villain, G., Balayssac, J.-P., Garnier, V., Sbartaï, M., Yven, B., Hénault, J.-M., Dérobert, X., Chaix, J.-F., Le Cam, V., Palma Lopes, S., Abraham, O., Projet SCaNING : Suivi des infrastructures neuves et existantes par Capteurs Noyés pour évaluer les Indicateurs Nécessaires à leur Gestion durable. Academic Journal of Civil Engineering, 2021, 38(2), 94-98. journal.augc.asso.fr/index.php /ajce/article/view/2493/2153 (Diagnobéton 2020, Bordeaux)

Ibrahim, H., Villain, G., Balayssac, J.-P., Dérobert, X., Palma Lopes, S., Devie, T., Procédure de calibration et développement d’un capteur capacitif noyé pour garantir une bonne durabilité des structures en béton armé, 25ème Congrès Français de Mécanique CFM, Nantes, 29 août au 2 septembre 2022 (article + présentation orale courte + poster)

H. Ibrahim, G. Villain, JP. Balayssac, X. Dérobert, S. Palma Lopes, C. Fauchard, V. Guihard, Calibration process of a capacitive probe for monitoring of reinforced concrete nuclear structures, NDE-NucCon - International Conference on Non-destructive Evaluation of Concrete in Nuclear Applications, January 25-27, 2023, Espoo, Finland.

R. Hariri, V. Garnier, J-F. Chaix, O. Abraham, Monitoring of concrete property gradients by embedded ultrasonic sensors, NDE-NucCon - International Conference on Non-destructive Evaluation of Concrete in Nuclear Applications, January 25-27, 2023, Espoo, Finland.

For a detailed diagnosis and the recalculation of the service life duration in order to extend the exploitation period of transportation and nuclear structures in concrete, their managers require qualified and continuous measurements of the indicators of concrete performances (compressive strength, elastic modulus, porosity and water content). The SCaNING project aims at developing a systemic structural health monitoring approach, for both new and existing reinforced concrete structures. It will rely on (i) the validation of electric, electromagnetic and ultrasonic embedded sensors, (ii) in depth data analysis to extract the qualified observables, compensated from environmental factors (particularly temperature), (iii) the combination and the conversion of observables into indicators. These embedded sensors have also the advantage of providing very rich quantitative and local information. Therefore, they can serve as a reference for non-destructive evaluations carried out at the structure surface and thus enable these latter to be calibrated and made reliable for a quantitative mapping of the whole structure.
As previous projects on non-destructive evaluation of concrete durability indicators have shown the need to combine testing methods, we will develop measurement systems based on different physical principles using ultrasonic, electromagnetic and electrical sensors. By capitalizing on knowledge from the literature on structural health monitoring, we will adapt data processing approaches for cleaning the measurements from adverse effects such as temperature variations. A multi-physical, operational and uncertainty-based combination method will be designed, then confronted with existing methods (data fusion, artificial neural networks and open-source software « OpenTurns » www.openturns.org used in the industry) during a benchmark based on the data obtained from the mock-ups implemented in this project.
Embedded sensors are useful for monitoring evolutions in new civil engineering structures and buildings. However, since ancient structures are much more numerous, ageing and usually of strategic importance to the owner, they must be subject to enhanced survey and maintenance. It is therefore crucial to design sensors to monitor their health, which are different from conventional temperature, displacement, or stress/strain sensors. To obtain qualified and reliable indicators, we want to adapt the systemic approach of cleaning, calibration and combination to sensors implanted in existing structures. Thus, the reinforced concrete mock-ups will be duplicated: one for the sensors embedded in fresh concrete and the other for sensors placed inside reservations several months after casting. The system for monitoring, storage and communication of the data collected by the sensors will be also developed.
The expected deliverables are ultrasonic, electromagnetic and electrical sensors, the methodology ranging from recommendations for installation to the extraction of qualified indicators with their uncertainties, useful to operators. The instrumented mock-ups, equipped with the acquisition systems, will be connected to a server to make the data accessible to the whole consortium during the project and then made available in open access to the scientific community after the finalisation and valorisation of the ANR SCaNING project.