Finite element models for the thermo-chemo-mechanical analysis of concrete structures regarding ageing and damage

• Ano de defesa: 2020
• Autor(a) principal: Costa, Gustavo Luz Xavier da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal do Rio de Janeiro; Brasil; Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia; Programa de Pós-Graduação em Engenharia Civil; UFRJ
• Palavras-chave em Português: Termo-quimio-mecânica; Concreto; Envelhecimento; Elemento finito; Engenharia Civil
• Link de acesso: http://hdl.handle.net/11422/23239

This study will address the thermo-chemo-mechanical behaviour of concrete considering ageing and damage. To this end, mathematical models will be developed and worked out through the Finite Element Method. The analysis will be composed of two models, namely: thermo-chemical and thermo-mechanical. First, the thermo-chemical model will be deduced using thermodynamics applied to chemically reactive porous media. One of the examples used to validate the thermo-chemical model consists of a concrete structure built by layers. For this case, it was developed a renumbering strategy for the nodes of the mesh. Then, the thermo-mechanical model will be presented as well as the necessity for an incremental constitutive equation for modelling concrete ageing. The ageing is translated by the increase of Young’s modulus, that is, by the cement hydration. Next, an isotropic damage model will be incorporated to the thermomechanical model with ageing and a Nonlocal integral-type strategy will be adopted to avoid lack of objectivity due to strain localization. Finally, the thermo-chemo-mechanical model will be presented by means of two theoretical examples: a concrete specimen and a generic concrete wall. The results will show that microcracks and residual stresses might take place due to hydration of cement. This in turn might lead to the premature collapse of the structure.