Antoine Crinière

The detection and thermal characterization of the inner structure of the ‘Musmeci’ bridge deck by infrared thermography monitoring

Since late 2014, the project Cloud2SM aims to develop a robust information system able to assess the long term monitoring of civil engineering structures as well as interfacing various sensors and data. Cloud2SM address three main goals, the management of distributed data and sensors network, the asynchronous processing of the data through network and the local management of the sensors themselves [1]. Integrated to this project Cloud2IR is an autonomous sensor system dedicated to the long term monitoring of infrastructures. Past experimentations have shown the need as well as usefulness of such system [2]. Before Cloud2IR an initially laboratory oriented system was used, which implied heavy operating system to be used [3]. Based on such system Cloud2IR has benefited of the experimental knowledge acquired to redefine a lighter architecture based on generics standards, more appropriated to autonomous operations on field and which can be later included in a wide distributed architecture such as Cloud2SM. The sensor system can be divided in two parts. The sensor side, this part is mainly composed by the various sensors drivers themselves as the infrared camera, the weather station or the pyranometers and their different fixed configurations. In our case, as infrared camera are slightly different than other kind of sensors, the system implement in addition an RTSP server which can be used to set up the FOV as well as other measurement parameter considerations.

Inverse model for defect characterisation of externally glued CFRP on reinforced concrete structures: comparative study of square pulsed and pulsed thermography

The objective of the study summarised, hereafter, is to compare square pulsed and pulsed thermography for defect detection and characterisation of carbon fibre-reinforced polymer (CFRP) plates used as structural reinforcement in Civil Engineering applications. For this purpose, two specimens built with cement concrete support were manufactured in the laboratory. They were reinforced with CFRP plates bonded to their surface and different artificial defects were inserted during gluing. Two types of thermal excitations (pulse and square pulse optical heating) have been studied and applied to these specimens. In parallel, numerical simulations were carried out as well. Defect detection was rapidly performed using singular value decomposition both on experimental and simulated thermal image sequences. A 1D multi-layer thermal quadrupole model coupled to an estimation procedure was studied. Validity domain of the 1D hypothesis is studied. Then this model is used to characterise the defects and the glue layer thickness. In addition, a sensitivity study of the proposed model is also presented. Furthermore, 3D numerical simulations were conducted to study the reliability of the estimation procedure vs. the two types of thermal excitations. The estimation procedure on numerical data provides results closer to experimental observations when applied to the square pulse method and it is less disturbed by white noise, even though a preliminary estimation residue analysis indicated that the heat pulse method should be, in theory, more precise. Finally, the estimation procedure studied herein was applied to experimental data acquired on laboratory specimens. Results obtained are analysed and perspectives for the presented method are discussed.