The design of a precast structural system requires joints between the structural elements, and concrete corbels are commonly used in the connection between beams and columns. Concrete corbels create an obstacle in the optimization of precast production, mainly of columns that have two or more concrete corbels in different faces. In these cases, the concrete corbels need to be manufactures in a different stage from the column, which requires attention to the interface between column and corbel, and some solution to ensure the continuity of the main tie reinforcement. For this paper, tests were conducted along with analytical and computational modeling of five concrete corbels models: one monolithic model and four where the corbels are manufactured in a different stage from the column. Results show the failure mode, the interface gap opening and the accuracy of the analytical and computational predictions. It was observed that the concrete corbels with bent main tie reinforcement displayed the largest gap-opening at the interface and that the computational modeling represented the strength of the monolithic concrete corbel better than the design code models.
RESUMO: Uma das principais vantagens das estruturas de concreto pré-moldado é a rapidez da execução. Essa vantagem pode ser ainda mais evidenciada se peças como pilares com consolos puderem ser produzidas de forma ainda mais ágil. Este artigo apresenta os resultados de uma pesquisa experimental em consolos curtos de concreto pré-moldado. Os consolos são pré-moldados separadamente do pilar e unidos ao mesmo mediante encaixe e protensão não aderente. Para isso, foram confeccionados três modelos formados por um pilar e dois consolos simétricos, todos pré-moldados, sendo que a ruína se deu por fendilhamento do concreto dos consolos. Os resultados também apontaram que a tipologia de consolo proposta apresentou capacidade resistente apenas 5% menor que do consolo monolítico de referência. Por outro lado, a tipologia de consolo proposta neste trabalho proporcionou capacidade resistente consideravelmente superior à encontrada para a tipologia de consolo moldado em duas etapas sem o uso de protensão.ABSTRACT: One of the key advantages of precast concrete structures is the speed of construction. This advantage can be further evidenced if elements like columns with corbels could be produced in an even more agile way. This paper presents the results of an experimental research on short precast concrete corbels. Corbels are precast separately of the column and then joined to it by means of socked and unbonded post-tensioning. For this, three models composed by a column and two symmetric corbels, all of them precast, were produced, being their failure defined by splitting of concrete in corbels. Results also demonstrated that the proposed typology of corbel presented strength merely 5% lower than the reference monolithic corbel. In the other hand, the proposed typology of corbel provided strength significantly greater than that found for corbel cast in two steps without prestressing.
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