Conception de poutres composites Bois-Béton avec emphase sur le comportement au jeune âge et l'utilisation des planchers CLT-BFUP

Authors: Nguyen, Truong Thanh
Advisor: Sorelli, LucaBlanchet, Pierre
Abstract: The use of timber-concrete composite (TCC) structures is increasingly popular thanks to their advantages of bearing capacity, eco-efficiency, and affordability. Research on this type of structure is still new and its development potential is therefore very promising. This Ph.D. project aims to research the static behavior and the early age behavior of TCC structures. The static behavior of TCC structures can be divided into two phases (elastic and inelastic) and there are several methods to predict the bearing behavior for each: • In the elastic phase, the γ-method is the best known thanks to its simplicity and precision in estimating the deflection and the frequency of vibration. This method is based on the sinusoidal load assumption and therefore there are errors in estimating the axial force and slip of TCC structures under other types of loads. In this project, an analytical method is developed to adjust the Gamma method by reducing the error from 22% to 2%. • In the inelastic phase, the existing analytical methods are either complex or less exact because of the post-elastic behavior of the connector. To solve the problem, an analytical model is developed considering the generally elastoplastic behavior of the connector and applying the point-to-point approach to predict the structural behavior of CBB structure. Finally, an engineering method is proposed to simplify the use of the model. On the other hand, concrete is a special material where its rigidity and strength develop over time after pouring. Its mechanical properties are generally normalized at 28 days when they reach relatively high values to satisfy the design of structures. Consequently, the behavior of concrete in the early-age period (before 28 days) is less studied, especially in TCC structures. This Ph.D. project focuses on two points concerning this behavior: • The waterproof plastic sheet is traditionally installed between cross-laminated timber (CLT) and concrete in the construction phase to prevent the exchange of moisture between two materials during concrete early-age. This insulation causes increased construction cost and decreased notch-type connector competence. Therefore, experimental research is carried out to verify if this insulator is necessary or it can be removed while ensuring the competence of TCC structures. • Another test campaign is carried out to assess the influence of early-age concrete shrinkage on the deflection and bearing capacity of the cast-in-place TCC floors. Simultaneously, an analytical model is developed to evaluate the experimental data. The result shows that the shrinkage of the concrete causes a very large deflection and a significant decrease in the rigidity of the TCC floors. Finally, the project can bring remarkable scientific contributions and industrial benefits. In addition, it opens potential research perspectives in this research field.
Document Type: Thèse de doctorat
Issue Date: 2022
Open Access Date: 16 May 2022
Grantor: Université Laval
Collection:Thèses et mémoires

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