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Master's Dissertation
DOI
https://doi.org/10.11606/D.18.2020.tde-06012020-124553
Document
Author
Full name
Isabela Zulini
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2019
Supervisor
Committee
Debs, Ana Lucia Homce de Cresce El (President)
Almeida Filho, Fernando Menezes de
Trautwein, Leandro Mouta
Title in Portuguese
Efeito do confinamento na aderência entre barras de aço e concreto de alta resistência à compressão
Keywords in Portuguese
Aderência aço-concreto
Armadura transversal
Concreto de alta resistência
Confinamento
Ensaio de arrancamento
Fibras de aço
Abstract in Portuguese
O presente trabalho buscou investigar o efeito do confinamento no comportamento da aderência em concreto de alta resistência, na faixa de 70 MPa. Para isso, foram realizados ensaios de arrancamento de carregamento monotônico com um trecho aderente central de comprimento igual a três vezes o diâmetro da barra longitudinal isolado por trechos não aderentes de cinco vezes o diâmetro da barra, variando os seguintes parâmetros: diâmetro da barra longitudinal, de 10 mm, 16 mm e 20 mm; cobrimento de concreto, sendo a relação entre o diâmetro do corpo-de-prova e da barra igual a 8, 9 e 15; adição de fibras de aço, no teor volumétrico de 1%; e inclusão de armadura transversal helicoidal. A partir da análise experimental, foi possível verificar que o aumento no diâmetro da armadura longitudinal promoveu um aumento na tensão de aderência máxima e no deslizamento último, exceto no caso onde houve a mudança de ruptura de arrancamento para fendilhamento (de 16 mm para 20 mm). Também, constatou-se que a inclusão de fibra metálica no concreto de alta resistência foi o mecanismo mais eficiente de confinamento no âmbito da aderência. Além disso, os resultados obtidos experimentalmente foram comparados com os modelos teóricos de autores da literatura e com as equações para a resistência de aderência descritas nas normas brasileira, americana e europeia. Por fim, concluiu-se que todas as prescrições normativas estão a favor da segurança, com uma grande margem de tolerância para a resistência de aderência.
Title in English
Effects of confinement in bond between reinforcement bar and high strength concrete
Keywords in English
Bond steel-concrete
Confinement
High Strenght Concrete
Pull-out test
Steel fiber
Stirrup
Abstract in English
The present work investigates the effect of the confinement on the behavior of bond in high strength concrete, around 70 MPa. In order to aim this objective, it was made several monotonic pull-out tests with a central bond length equal to three times the rebar diameter isolated by bond-free lengths of five times the rebar diameter, changing the following parameters: rebar diameter, of 10, 16 and 20 mm; concrete cover, with a ratio between the concrete diameter and the rebar diameter of 8,9 and 15; including steel fiber, at a volumetric rate of 1%; and including spiral reinforcement. By the experimental analysis, it was possible to verify that increasing the rebar diameter made the maximum bond stress and slip also increase, except for the case where the rupture changed from splitting to pull-out (from 16 mm to 20 mm). Also, it was found that including steel fiber in high strength concrete showed to be the most efficient confinement's mechanism within the bond behavior. Besides, the experimental results were compared to the theoretical models proposed by authors from the literature and to the equations for bond strength from the Brazilian, American and European model codes. Lastly, it was concluded that all the model codes are in favor of safety, with a large margin of tolerance for bond strength.
 
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Publishing Date
2020-01-14
 
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