Approche poro-mécanique au fluage non linéraire du béton : expérimentation et modélisation

Authors: Pham, Duc Tho
Advisor: Sorelli, LucaFafard, Mario
Abstract: Knowledge of the delayed behaviour of concrete subjected to a high load is necessary for predicting the serviceability of concrete structures. In particular, in the case of civil engineering structures, this knowledge is an influential aspect for predicting deflection, development of microcracking in concrete structures, stress redistribution in hyperstatic structures and prestressing losses in pre-stressed concrete structures. Moreover, the prediction of the evolution of cracking with time in order to estimate the lifetime of structures is an advantageous and promising prospect that only numerical models relevant to the mechanisms of cracking of concretes can offer. The objective of this work is first to investigate the mechanisms of tertiary creep in concrete and then to develop a numerical model to simulate the nonlinear creep behaviour which is supposed to cause the interaction between relative humidity and microcracking in order to predict the deflection and the crack opening as well as the lifetime. This model was developed in the OOFEM finite element code, based on the lattice method. To perform this, three programs were launched. The first one was to validate the hydromechanical coupling problem by examining the evolution of the permeability of reinforced concrete under tensile loading. The second program aimed at developing and implementing the non-linear equations of the relative humidity transfer coupled with damage mechanics to predict the crack opening of the four points bending test on pre-cracked beam subjected to a high sustained load. Lastly, the experimental program was carried out on beams notched to validate the proposed model, using the digital image correlation technique. The effects of heterogeneity and the water-to-cement ratios (E/C) were considered to estimate the effect of those parameters during the evolution of the crack opening. The results show that the proposed numerical model is capable of simulating the deflection and crack opening with time of fiber reinforced concrete (FRC) under high sustained loads.
Document Type: Thèse de doctorat
Issue Date: 2017
Open Access Date: 24 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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