Avaliação experimental de colunas CFST curtas com núcleo de concreto reciclado

• Autor(a) principal: Azevedo, Vanessa da Silva de
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/11469
• topic: Civil Engineering; Columns; Mixed construction; Structural analysis (engineering); Circular Composite Sections; Short Columns, Steel Tube Seam; Engenharia civil; Colunas; Construção mista; Análise estrutural (Engenharia); Seções Mistas Circulares; Colunas Curtas, Perfis Tubulares com Costura; CNPQ::ENGENHARIAS::ENGENHARIA CIVIL

Although the use of tubular steel profiles filled with concrete is widely used in a combination of lightness and strength, this perspective undergoes regulatory actions applicable to composite elements that are not yet fully understood and need to be investigated in detail. Thus, relevant research approaches to behavior analysis of composite stub columns with steel seamed tubular sections filled with concrete, better known as Concrete-Filled Steel Tubes (CFST) and filled with recycled aggregate concrete, known as Recycled Aggregate Concrete-Filled Steel Tube (RACFST), where the adopted recycled coarse aggregate percentage was equal to 30% and 50%. In respect to the premises necessary for the concrete to steel interaction, the influence of the concrete confinement is investigated as well as the concrete internal rearrangement when it the recycled coarse aggregate is utilized. It is noticed that the variations of the concrete characteristic resistance and the recycled aggregate rate impact in a unique way the composite section characteristics when there is an effective control over the adopted recycled coarse aggregate, which in this case derives of specimens associate to a concrete characteristic resistance around 40 MPa. The experimental results have shown that the concrete core enhances the composite section load carrying capacity. However, the control over the contents of this concrete core influences on the ductility of the composite section, since, if the behavior of the fill material is fragile, the stress redistributions for both the steel and the concrete will compensate this response. It is also fair to observe that the concrete core is essential to inhibit a possible inner local buckling of the tubular section. Since the behavior of CFST and RACFST columns is still widely discussed, the present thesis starts from a study based on a comparative assessment of the recommendations present in ABNT NBR 8800:2008, ABNT NBR 16239:2013 and EN 1994-1-1 design standards. These design recommendations proved to be consistent and in line with the performed experiments. The concrete confinement stresses can be divided into three distinct stages: the first (elastic) stage, second (yield) stage, elastic, and third stage associated with large deformations. The results indicated that the D/t slenderness ratio and the confinement ratio ξ, directly influence the composite section behavior providing a combined effect that enhances its load carrying capacity.