03 Décembre – Thesis defense - Shuang Peng

14 h Full videoconferencing

Advance on non-destructive evaluation methodologies for the material characterization and damage monitoring of masonry structures.

In the context of the preservation of masonry heritage, the structure diagnosis is essential for two main aims: (i) material assessment (ii) damage assessment. The non-destructive techniques (NDT) are privileged for the investigation and the assessment of structure condition, particularly in masonry architectural heritage field. The present work aims to understand the process of material deterioration and to investigate the performance of NDT at the material physico-mechanical characterization and crack monitoring.
The first study addresses the material characterization by different types of non-destructive techniques. As water is considered as a crucial parameter in the material deterioration, the influence of water saturation degree on the physico-mechanical properties of different types of limestone is firstly discussed. Three NDT methods including ultrasound, electrical resistivity and radar are performed to explore the relationship between the non-destructive parameters and the physico-mechanical properties. A good agreement is observed between the ND parameters, porosity, and water saturation. Different analytical modeling of NDT behaviors was also proposed that showed satisfactory results in comparison with experimental tests.
The second study focus on the performance of acoustic emission technique (AET) for the mechanical damage monitoring in the masonry structure. This technique is investigated at multiscale experimental tests from the mesoscopic scale (bloc-mortar-bloc) to the macroscopic scale (shear wall). At the mesoscopic scale, the AET was applied to a series of small-scale laboratory specimens under tensile and shear loading. A mechanical analysis is firstly required to characterize both cracking modes. Different AE indices (hit number and hit energy) are correlated with damage accumulation to identify its response to each loading. AE duration parameter is found distinctive to discriminate signal from different sources. To validate these observations at the macroscopic scale, a series of full-scale test as a shear wall under compression was carried out in parallel with the AET and the digital image correlation (DIC). Comparing with the DIC results, the AET shows a good performance of damage assessment as well as source characterization in masonry at a more complex mechanism of failure.

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