Behaviour of concrete-filled double-skin stub columns with recycled aggregate concrete subjected to concentric and eccentric load

• Ano de defesa: 2021
• Autor(a) principal: Castanheira, Deborah Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade do Estado do Rio de Janeiro; Centro de Tecnologia e Ciências::Faculdade de Engenharia; Brasil; UERJ; Programa de Pós-Graduação em Engenharia Civil
• Palavras-chave em Português: Civil engineering; Columns; Mixed construction; Structural analysis (Engineering); Numerical analysis; Engenharia civil; Colunas; Construção mista; Análise estrutural (Engenharia); Análise numérica; ENGENHARIAS::ENGENHARIA CIVIL::ESTRUTURAS
• Link de acesso: http://www.bdtd.uerj.br/handle/1/17236

Concrete-filled double-skin tubular (CFDST) columns are a relatively new type of structural element, and their use is becoming very popular. One of their advantages is light and less expensive construction due to less material and formwork. Nowadays, the employment of stainless steel and recycled aggregate concrete (RAC) in composite elements is hugely topical due to less expensive manufacturing and sustainability issues since both materials are fully recyclable. This thesis presents an experimental and numerical study into the behaviour of CFDST stub columns. In contrast, the experiments were subjected to concentric axial load, and the numerical were subjected to concentric, eccentric axial load and pure bending. Four axial compression tests were carried out filled with recycled aggregate concrete and afterwards compared with CFDST columns filled with conventional concrete found in the literature. The columns had circular tubular cross-sections, and each comprised an austenitic stainless steel outer tube and a carbon steel inner tube with variable dimensions. A replacement ratio of 50% of natural coarse aggregate (NCA) by recycled coarse aggregate (RCA) was adopted in the RAC tests. During the tests, similar structural behaviour was observed in the columns with conventional or recycled aggregate concrete, while the failure modes proved to be identical. To further investigate the behaviour, a finite element model was developed in ABAQUS and was validated against the experiments and the literature's data. The finite element model was employed to conduct a parametric study to assess the influence of different geometric, concrete compressive strength (fc), the recycled coarse aggregate concrete and eccentricity load application on the behaviour of CFDST stub columns. An N-M interaction diagram is generated to compare with available design procedures for CFDST stub columns and beam-columns. Finally, a reliability study was conducted to assess the proposed N-M interaction diagram. Overall, the results demonstrated that the CFDST stub columns with recycled aggregate concrete achieve a very similar ultimate load capacity to similar members with conventional concrete. However, current design expressions provide some unsafe results. The developed concrete confinement factor, axial load capacity, pure bending moment and N-M interaction diagram demonstrate to be in good agreement with the experiments and FE results evaluated.