Abstract
A new experimental method which allows the direct separation of the components of drying creep due to microcracking and stress-induced shrinkage is developed, demonstrated and validated. The basic idea is to compare the curvature creep of beams subjected to the same bending moment but very different axial forces. The results confirm that drying creep has two different sources: microcracking and stress-induced shrinkage. The latter increases continuously, whereas the former first increases and then decreases. The test results are fitted using a finite element model. The results validate the present model for drying creep. The microcracking is described by an established model, and the free (unrestrained) shrinkage of a material element is shown to depend approximately linearly on the humidity drop.
Resume
On a développé, démontré et validé une nouvelle méthode expérimentale permettant d'identifier directement les composantes du fluage au séchage dû à la microfissuration et à la contrainte de retrait. L'idée de base est de comparer le fluage en flexion de poutres soumises au même moment fléchissant mais de faire varier les différentes forces axiales.
Les résultats confirment que le fluage au séchage a deux origines différentes: la microfissuration et le retrait sous contrainte. Celui-ci augmente de façon continue alors que celle-là augmente d'abord, puis diminue. On a utilisé un modèle d'élément fini pour ajuster les résultats d'essai qui valident le modèle actuel pour le fluage au séchage. On décrit la microfissuration par un modèle établi; quant au retrait libre (non empêché) d'un élément de matériau, on montre qu'il dépend de la chute d'humidité de façon approximativement linéaire.
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Bažant, Z.P., Yunping, X. Drying creep of concrete: constitutive model and new experiments separating its mechanisms. Materials and Structures 27, 3–14 (1994). https://doi.org/10.1007/BF02472815
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DOI: https://doi.org/10.1007/BF02472815