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Analyse des contraintes in situ dans les structures en béton armé

Abstract : Concrete is the most widely used manufactured material in construction around the world. The recent accidents of reinforced concrete buildings and structures, in France and abroad, show that a massive investment in their maintenance is necessary. This maintenance is all the more necessary that a maximum of these structures, built after the Second World War, are now reaching the end of their life. These disasters, added to the natural risks accentuated by climate change, have created a feeling of insecurity for users and local elected officials. The scientific and technical issue is therefore to help decide on the viability of reinforced concrete structures. This concerns buildings, in particular in the context of energy rehabilitation, but also structures in the context of extending their lifespan. Our study focuses more particularly two mechanical index useful for the diagnosis of reinforced concrete structures: the field of stresses in situ, to control the safe operating of the structure, and the Young's modulus of the material which allow to know the quality of the concrete. The concept retained to determine these two data on site is based, first level, on a local release of stresses which is minimally invasive for the structure. Secondly, the liberated and studied zone is recharged but weakly. This controlled reloading provides the determination of the material's Young's modulus. The identification of constrained and unconstrained states is done using digital image correlation (CIN) techniques specifically developed for these measurements. The experimental challenge lies in the precise determination of the stresses. An accuracy of 1 MPa is necessary for an objective determination of the Young's modulus. Consequently, the precision on the measurement of displacement fields by image correlation is of the order of a micron, which is not usual in civil engineering. In addition, the proposed method being applied in situ, the measurement tools have been developed to meet industrial requirements and standards, which further accentuated the challenge.
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https://theses.hal.science/tel-03600828
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Submitted on : Monday, March 7, 2022 - 7:53:08 PM
Last modification on : Tuesday, March 8, 2022 - 3:28:33 AM
Long-term archiving on: : Wednesday, June 8, 2022 - 9:39:32 PM

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  • HAL Id : tel-03600828, version 1

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Marie Allain. Analyse des contraintes in situ dans les structures en béton armé. Génie civil. Université Savoie Mont Blanc, 2021. Français. ⟨NNT : 2021CHAMA004⟩. ⟨tel-03600828⟩

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