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InfluĂȘncia das elevadas temperaturas e as propriedades mecĂąnicas residuais do concreto normal
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Advisor(s)
Abstract(s)
O concreto, de um modo geral, apresenta um bom comportamento em situação de incĂȘndio quando comparado
com o aço, todavia em função da temperatura ocorrem algumas transformaçÔes quĂmicas e fĂsicas que podem
comprometer esse desempenho. Apesar das alteraçÔes das propriedades mecùnicas e térmicas do concreto
quando sujeito a temperaturas elevadas e apĂłs situação de incĂȘndio jĂĄ terem sido avaliadas em vĂĄrios estudos,
ainda é um campo aberto onde é necessårio muita investigação. O presente artigo apresenta os resultados de um
estudo experimental sobre a avaliação das propriedades mecĂąnicas residuais de concretos normais apĂłs incĂȘndio.
Para o efeito foram selecionados agregados granĂticos e agregados calcĂĄrios, dado serem os agregados mais
utilizados na construção civil em Portugal e em muitos outros paĂses. Os parĂąmetros testados foram: o nĂvel de
carregamento (0,3fcd e 0,7fcd); o processo de arrefecimento (arrefecimento ao ar e arrefecimento por jato de ĂĄgua)
e o nĂvel mĂĄximo de temperatura atingida (20, 300, 500 e 700ÂșC). As propriedades mecĂąnicas estudadas foram a
resistĂȘncia Ă compressĂŁo residual, resistĂȘncia Ă tração direta e resistĂȘncia Ă tração por compressĂŁo diametral,
resistĂȘncia Ă flexĂŁo, mĂłdulo de elasticidade e coeficiente de Poisson. As temperaturas atingidas e o
arrefecimento rĂĄpido do concreto apresentaram um efeito negativo sobre as propriedades mecĂąnicas residuais.
Este efeito foi mais notĂłrio na resistĂȘncia Ă compressĂŁo residual do que nas restantes propriedades mecĂąnicas
estudadas.
ABSTRACT: Concrete is known to have an enhanced behaviour in fire when comparing with bare steel, however there are some chemical and physical transformations in function of temperature that may compromise this performance. The mechanical and thermal properties of concrete at high temperatures and after fire have changes that have been evaluated in a lot of works, however this is still an open field where a lot of research is needed. This paper presents the results of a research on the assessment of the residual mechanical properties of ordinary concretes after fire. It was chosen for studying granite and calcareous aggregate concretes, as they are the most used in the civil construction in Portugal and in a lot of countries around the world. The following parameters were tested: loading level (0.3fcd and 0.7fcd), cooling process (cooling in the air and cooling by water jet) and maximum temperature level attained (20, 300, 500 and 700ÂșC). The mechanical properties studied were the residual compression, direct and splitting tensile and flexural strengths, modulus of elasticity and Poissonâs ratio. The high temperatures attained and the rapid cooling process on the concrete showed a negative effect on its residual mechanical properties. This effect was more notorious in the residual compression strength than in the other mechanical properties.
ABSTRACT: Concrete is known to have an enhanced behaviour in fire when comparing with bare steel, however there are some chemical and physical transformations in function of temperature that may compromise this performance. The mechanical and thermal properties of concrete at high temperatures and after fire have changes that have been evaluated in a lot of works, however this is still an open field where a lot of research is needed. This paper presents the results of a research on the assessment of the residual mechanical properties of ordinary concretes after fire. It was chosen for studying granite and calcareous aggregate concretes, as they are the most used in the civil construction in Portugal and in a lot of countries around the world. The following parameters were tested: loading level (0.3fcd and 0.7fcd), cooling process (cooling in the air and cooling by water jet) and maximum temperature level attained (20, 300, 500 and 700ÂșC). The mechanical properties studied were the residual compression, direct and splitting tensile and flexural strengths, modulus of elasticity and Poissonâs ratio. The high temperatures attained and the rapid cooling process on the concrete showed a negative effect on its residual mechanical properties. This effect was more notorious in the residual compression strength than in the other mechanical properties.
Description
Keywords
Concreto IncĂȘndio Residual Propriedades mecĂąnicas Concrete Fire Residual Mechanical properties
Pedagogical Context
Citation
SANTOS, Cristina Calmeiro dos; Rodrigues, JoĂŁo P. C. (2015) - InfluĂȘncia das elevadas temperaturas e as propriedades mecĂąnicas residuais do concreto normal. In Congresso Ibero-Latino-Americano Sobre Segurança Contra IncĂȘndios, 3, Porto Alegre, 3-6 de Novembro. Porto Alegre: [s.n.]. p. 1-16