Experimental evaluation of the residual concrete-reinforcement bond after exposure to elevated temperatures

• Ano de defesa: 2021
• Autor(a) principal: Andrade, Matheus Sant’Anna
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Engenharia Civil
• Palavras-chave em Português: Concreto armado; Aderências; Concreto armado - Efeito da temperatura; Deformações e tensões - Métodos gráficos; Engenharia Civil
• Link de acesso: https://locus.ufv.br//handle/123456789/29849; https://doi.org/10.47328/ufvbbt.2022.070

The composite behavior of reinforced concrete structures is directly related to the bond between concrete and reinforcement. When a reinforced concrete structure is subjected to a fire event, the bond is damaged and the force-transfer mechanism is compromised, as well as the resistant capacity of the structure itself. This study consists of a review of post-fire concrete- reinforcement bond relationship and an experimental assessment of the influence of exposure to elevated temperatures on the bond between these materials. First, it was reviewed the state- of-the-art research on post-fire bond properties, as well as the parameters influencing bond relationship development after exposure to elevated temperatures. This work also presents an experimental assessment of the influence of degradation of concrete and reinforcing steel, induced by elevated temperatures, on the bond relationship between the materials and the influence of concrete cover to bar diameter ratio on concrete-reinforcement bond failure mechanism. The findings showed that bond degradation is directly related to the damage to the concrete and that the reinforcing steel is negligibly affected by temperatures under 600 ºC. It was also observed that exposure at 200 ºC had a positive effect both on the residual mechanical properties of concrete and residual bond strength. Exposure to higher temperatures progressively reduced the mechanical properties of concrete and the bond strength measured after the fire situation. Moreover, the bond failure mechanism was observed to shift from pull- out to splitting due to the concrete damage at elevated temperatures, although it could not be easily distinguished. It was also concluded that, even though the data available on the literature are extremely scattered, the bond strength prescribed by international standards for structures design is safe both at room temperature and after exposure to elevated temperatures. Keywords: Reinforced concrete. Bond strength. Elevated temperatures. Bond-slip relationship. Bond failure mechanism.