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Estudo de colunas circulares de betão reforçadas com compósitos de fibra de carbono
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A reabilitação de edifícios é uma prática cada vez mais comum no seio da Engenharia Civil. Por
esta razão torna-se imprescindível a procura de novas técnicas e métodos de reforço capazes de
integrar construções já existentes. Nesse sentido, desenvolveu-se um estudo experimental sobre
o confinamento de pilares de betão, de secção circular, com recurso a uma argamassa reforçada
por uma malha têxtil unidirecional de fibras de carbono.
O principal objetivo deste trabalho é fazer uma caracterização do CFRCM (Carbon Fabric
Reinforced Cementitious Matrix) enquanto sistema de confinamento. Os compósitos de fibras,
nomeadamente os CFRP (Carbon Fiber Reinforced Polymer), têm uma grande procura no
mercado da construção porém apresentam algumas desvantagens que podem ser colmatadas por
esta técnica inovadora que combina os compósitos com uma matriz inorgânica.
A campanha experimental compreendeu a realização de ensaios de compressão uniaxial até à
rotura de doze modelos, dos quais dois diziam respeito a modelos de referência que não foram
reforçados. Relativamente aos modelos reforçados, estes dividem-se em duas séries, uma
reforçada com tecidos de fibras de carbono a outra com argamassa reforçada com malha têxtil de
fibras de carbono. Em ambas as séries fez-se variar o número de camadas. A aplicação do reforço
foi feita em toda a altura dos pilares, com os tecidos de fibras e a malha têxtil orientadas na direção
transversal dos pilares.
Analisaram-se os resultados experimentais, mediante vários parâmetros que caracterizam o
comportamento do betão confinado à compressão. Para ambos os reforços, foi possível aumentar
a força máxima de compressão do betão e a correspondente extensão axial. O reforço de CFRCM
apresentou algumas vantagens, nomeadamente a sua resposta pós pico, que suporta grandes
deformações até perder toda a sua capacidade resistente e também a facilidade na aplicação do
reforço face ao CFRP.
Building rehabilitation is an increasingly common practice in Civil Engineering. Thus, the search for new strengthening methods and techniques, adequate for existing constructions, is essential. With this in mind, an experimental study was carried out on the confinement of concrete columns, with circular section, using a mortar reinforced by an unidirectional carbon fiber textile mesh. The main objective of this study is to characterize the CFRCM (Carbon Fabric Reinforced Cementitious Matrix) as a confinement system. Fiber composites, namely CFRP (Carbon Fiber Reinforced Polymer), are in great demand for strengthening purposes, but they present some disadvantages that can be overcome by this innovative technique that combines composites with an inorganic matrix. The experimental testing campaign consisted of a sequence of uniaxial compression failure tests, using twelve specimens, two of which were reference unstrengthened models. The strengthened specimens, were divided into two series, one strengthened with carbon fiber sheets and another with mortar reinforced with a carbon fiber textile mesh. In both series, the number of layers were varied. The strengthening was applied over the whole height of the columns, with the fibers of the jackets and the textile mesh oriented in the transverse direction of the columns. The experimental results were analyzed using several parameters that characterize the compressive behavior of confined concrete. Both strengthening solutions made possible to increase the maximum load and the corresponding axial strain. The CFRCM reinforcement presented some advantages, namely its post-peak response, supporting larger deformations until losing all its load bearing capacity, but also its simpler application when compared with the CFRP alternative.
Building rehabilitation is an increasingly common practice in Civil Engineering. Thus, the search for new strengthening methods and techniques, adequate for existing constructions, is essential. With this in mind, an experimental study was carried out on the confinement of concrete columns, with circular section, using a mortar reinforced by an unidirectional carbon fiber textile mesh. The main objective of this study is to characterize the CFRCM (Carbon Fabric Reinforced Cementitious Matrix) as a confinement system. Fiber composites, namely CFRP (Carbon Fiber Reinforced Polymer), are in great demand for strengthening purposes, but they present some disadvantages that can be overcome by this innovative technique that combines composites with an inorganic matrix. The experimental testing campaign consisted of a sequence of uniaxial compression failure tests, using twelve specimens, two of which were reference unstrengthened models. The strengthened specimens, were divided into two series, one strengthened with carbon fiber sheets and another with mortar reinforced with a carbon fiber textile mesh. In both series, the number of layers were varied. The strengthening was applied over the whole height of the columns, with the fibers of the jackets and the textile mesh oriented in the transverse direction of the columns. The experimental results were analyzed using several parameters that characterize the compressive behavior of confined concrete. Both strengthening solutions made possible to increase the maximum load and the corresponding axial strain. The CFRCM reinforcement presented some advantages, namely its post-peak response, supporting larger deformations until losing all its load bearing capacity, but also its simpler application when compared with the CFRP alternative.
Descrição
Palavras-chave
Pilares de betão secção circular reforço estrutural confinamento CFRP CFRCM