Ligações formadas pelo transpasse de armadura dobrada em forma de laço: análise da influência das fibras de aço

• Autor(a) principal: Curado, Marina Craveiro
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/4331
• topic: Ancoragens curvas; Fibras de aço; Ligações em forma de laço; Curved anchorages; Steel fibers; Loop connections; ESTRUTURAS::MECANICA DAS ESTRUTURAS

Curved anchorages shall be used once there is the need of reducing the necessary length for the transference of stresses between reinforcement and concrete. The transference of stresses in this case is performed not only through the bond between both materials but also through radial compression onto the concrete. Besides enhancing the bond properties between the reinforcement and the concrete, the addition of steel fibers to the concrete also enhances the strength to material tension contributing to avoid the splitting within the loop level. This paper aims at studying connections resistant to normal tension force composed by the overlapping of bent bars into loop shape. In order to do so, an experimental program was developed to evaluate the influence of some variables in the anchorage strength and connections formed by bent bars into loop shape. In both cases, the bending diameter of the loop and the grade of steel fibers added to the concrete were adopted as variables. Different development lengths regarding the pullout experimental data were also considered in order to assess anchorage strength. The influence over connection strength of the transversal reinforcement presence to the loop level was also analyzed. The outcomes of experimental data showed that the adopted bending diameter to the loop have influenced neither anchorage strength nor connections. Anchorage strength is related to the development length of the reinforcement within the concrete. Once 2% of steel fibers were added to the concrete, there was yielding of the reinforcement into a development length of only 50 mm. Regarding the connections, the presence of transversal reinforcement ensured a gradual loss of force within the post-peak section. Such reinforcement only influenced the connection strength when it was used together with 1% steel fibers. The fibers provided additions to the anchorage strengths and to the connections allowing the length reduction of anchorage loops. The strut and tie model was employed within the development of one expression to the calculation of the studied connection strength. Overall, the proposed equation tended to underestimate the values of maximum force.