SCaNING

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.