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The use of steel fiber reinforced concrete (SFRC hereafter) is becoming more and more common. Building codes and recommendations are gradually including the positive effect of fibers on mechanical properties of concrete. How to take advantage of the higher ductility and energy absorption capacity of SFRC to reduce anchorage lengths when using fibers is not a straightforward issue. Fibers improve bond performance because they confine reinforcement (playing a similar role to that of transverse reinforcement). Their impact on bond performance of concrete is really important in terms of toughness/ductility. The study of previous literature has revealed important points of ongoing discussion regarding different issues, especially the following: a) whether the effect of fibers on bond strength is negligible or not, b) whether the effect of fibers on bond strength is dependent on any other factors such as concrete compressive strength or concrete cover, c) quantifying the effect of fibers on the ductility of bond failure (bond toughness). These issues have defined the objectives of this thesis. A modified version of the Pull Out Test (POT hereafter) has been selected as the most appropriate test for the purposes of this research. The effect of a number of factors on bond stress¿slip curves has been analyzed. The factors considered are: concrete compressive strength (between 30 MPa and 50 MPa), rebar diameter (between 8 mm and 20 mm), concrete cover (between 30 mm and 5 times rebar diameter), fiber content (up to 70 kg/m3), and fiber slenderness and length. The experimental program has been designed relying on the principles of statistical Design Of Experiments. This has allowed to select a reduced number of combinations to be tested without any bias or loss of accuracy. A total of 81 POT specimens have been produced and tested. An accurate model for predicting the mode of bond failure has been developed. It relates splitting probability to the factors considered. It has been proved that increasing fiber content restrains the risk of splitting failure. The favorable effect of fibers when preventing splitting failures has been revealed to be more important for higher concrete compressive strength values. Higher compressive strength values require higher concrete cover/diameter ratios for splitting failure to be prevented. Fiber slenderness and fiber length modify the effect of fiber content on splitting probability and therefore on minimum cover/diameter ratios required to prevent splitting failures. Two charts have been developed for estimating the minimum cover/ diameter ratio required to prevent splitting. Predictive equations have been obtained for estimating bond strength and areas under the bond stress¿slip curve as a function of the factors considered. Increasing fiber content has a slightly positive impact on bond strength, which is mainly determined by concrete compressive strength. On the contrary, fibers have a very important effect on the ductility of bond failure, just as well as concrete cover, as long as no splitting occurs. Multivariate analysis has proved that bond stress corresponding to the onset of slippage behaves independently from the rest of the bond stress¿slip curve. The effect of fibers and concrete compressive strength on bond stress values corresponding to the onset of slips is mainly attributable to their influence on the material mechanical properties. On the contrary, the effect of fibers and concrete cover on the rest of the bond stress¿slip curve is due to their structural role. / García Taengua, EJ. (2013). Bond of Reinforcing Bars to Steel Fiber Reinforced Concrete (SFRC) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32952 / TESIS

Load testing was performed on a one-third scale model steel fiber reinforced concrete post-tensioned flat plate. The specimen had nine 10ft x 10ft x 3in. bays along with a 2ft-6in. overhang. Distributed loading was applied with a whiffle tree loading system at each bay and overhang section. Throughout the test, crack widths, crack locations, deflections, concrete strains, and reinforcing bar strains were monitored. The post-tensioned flat plate was designed to just meet the maximum allowable stress requirements of ACI 318. Minimal quantities of hairline cracks were observed after stressing the slab, and up through service-level loads, the cracks grew slightly in length and width. The slab behaved elastically through service-level loading. As factored-level loading was approached, the slab began to behave inelastically as indicated by both the load-deflection plots and the load-strain plots. A total ultimate load of 282psf (174psf of applied load) was reached when concrete crushing occurred. A 0.20in. wide full-length crack was observed running on the bottom surface of the slab between column lines 1 and 2, and a full-length crack was observed at column line 2 on the top surface of the slab. These two cracks were the leading contributors to the slab's failure. The performance of the SFRC post-tensioned flat plate indicated that considerations should be made to remove requirements for negative moment reinforcement in post-tensioned flat plates when SFRC is used. Also, the requirements for positive moment reinforcement should be modified. Additionally, the SFRC post-tensioned flat plate exhibited excellent levels of ductility. More experimentation should be conducted to determine if the maximum tensile stress in ACI 318 can be increased for post-tensioned flat plates with SFRC. / Master of Science / Load testing was performed on a one-third scale model steel fiber reinforced concrete (SFRC) post-tensioned flat plate. Post-tensioned flat plates are a type of concrete structural system typically used as flooring. This system typically employs high-strength steel strands, which are stretched to introduce compression into the concrete, which helps prevent the onset of cracking. The specimen had nine 10ft x 10ft x 3in. bays along with a 2ft-6in. overhang. Distributed loading was applied with a whiffle tree loading system at each bay and overhang section. The whiffle tree loading system was used to allow actuators to spread out the vertical loading on the slab. During the test, crack widths, crack locations, deflections, concrete strains, and reinforcing bar strains were monitored. The post-tensioned flat plate was designed to just meet the maximum allowable stress requirements of the governing standard, ACI 318. Minimal quantities of hairline cracks were observed after stressing the slab, and up through service-level loads, the cracks grew slightly in length and width. As larger loads were applied, the cracks grew and the effects of these cracks on the slab were evidenced in the deflection and strain measurements. A total ultimate load of 282psf (174psf of applied load) was reached when concrete crushing occurred. A 0.20in. wide full-length crack was observed running on the bottom surface of the slab between column lines 1 and 2, and a full-length crack was observed at column line 2 on the top surface of the slab. These two cracks were a driving force in the slab’s failure. The performance of the SFRC post-tensioned flat plate indicated that considerations should be made to change the requirements for negative and positive moment reinforcement in post-tensioned flat plates when SFRC is used. Additionally, the SFRC post-tensioned flat plate exhibited great performance after significant cracking was present. More experimentation should be conducted to determine if the maximum allowable tensile stress in ACI 318 can be increased for post-tensioned flat plates with SFRC.

Orientador: Jorge Luís Akasaki / Banca: Jefferson Sidney Camacho / Banca: Antonio Domingues Figueiredo / Resumo: Os tubos de concreto são utilizados em larga escala nas canalizações dos sistemas de abastecimento de água em diâmetros superiores a 400 mm, esgoto sanitário, drenagem pluvial, bueiro e travessia. Suas vantagens e aplicabilidade têm motivado diversas pesquisas sobre esse produto, dentre as quais podemos destacar a utilização de tubos de concreto reforçados com fibras de aço em substituição total da armadura. As fibras de aço quando adicionadas ao concreto melhoram algumas propriedades, tais como: tenacidade, limitação de abertura de fissuras e resistência ao impacto. A pesquisa objetiva analisar o comportamento mecânico de protótipos de tubos de concreto confeccionados com diferentes teores de adições de fibras de aço, tais como: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, em substituição total da armadura. Também foram fabricados tubos de concreto simples e armados para uma análise comparativa do comportamento mecânico entre aqueles e os tubos com fibras. Os tubos de concreto possuem 600 mm de diâmetro nominal e 1,5 m de comprimento, destinados aos sistemas de drenagem de águas pluviais. As fibras de aço utilizadas possuem fator de forma igual a 75 e apresentam as seguintes características: 60 mm de comprimento médio e 0,80 mm de diâmetro médio. Os corpos-de-prova cilíndricos foram submetidos aos ensaios: resistência à compressão axial, resistência à tração na compressão diametral, e os corpos-de- prova prismáticos foram submetidos aos ensaios de tenacidade enquanto os tubos de concreto foram submetidos aos ensaios: resistência à compressão diametral e absorção de água (amostras retiradas dos tubos após ensaio de compressão diametral). Dos ensaios realizados se destaca o ensaio de compressão diametral pelo fato... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The concrete pipe is widely used in plumbing systems in water supplying in higher diameters 400 mm, sewage, water rain drainage, storm drain and crossing. Its advantages and functions have motivated a lot of researches about this product, among them can point out used concrete pipes reinforced with steel fibers replacing the conventional framework. The steel fibers when added concrete improvement some properties, such as: flexural toughness, limitation crack width and high strain rates strength. The current text refers to a study developed to evaluate the mechanical behavior of manufactured prototypes with steel fibers added in different contents, such as: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, replacing the conventional framework. Also were manufactured simple concrete pipes and concrete pipes with framework for analysis to compare the mechanical behavior between that one and steel fibers. The pipes used have 600 mm nominal diameter and 1,5 m length, used in systems in water rain drainage. The steel fibers used have aspect ratio 75 and present characteristics: 60 mm medium length and 0,80 mm medium diameter. The circular specimens were submitted the testing for: compressive strength, tensile strength by diametrical compressive, and the rectangular specimens were submittes the testing for flexural toughness while the concrete pipes were submitted the testing for: diametrical compressive strength and absorption of water (sample retreat of pipes after the testing for diametrical compressive strength). The testing for realized to point for diametrical compressive strength because the testing for the same concrete pipe and all particular characteristics for observed. The Brazilian specification NBR 8890 (ABNT, 2007) specify the testing for diametrical compressive... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-05-12Bitstream added on 2014-06-13T18:21:13Z : No. of bitstreams: 1 fugii_ap_me_ilha_prot.pdf: 6559082 bytes, checksum: e1ddcb7044b10a47da7e5f917d6bce83 (MD5) / Os tubos de concreto são utilizados em larga escala nas canalizações dos sistemas de abastecimento de água em diâmetros superiores a 400 mm, esgoto sanitário, drenagem pluvial, bueiro e travessia. Suas vantagens e aplicabilidade têm motivado diversas pesquisas sobre esse produto, dentre as quais podemos destacar a utilização de tubos de concreto reforçados com fibras de aço em substituição total da armadura. As fibras de aço quando adicionadas ao concreto melhoram algumas propriedades, tais como: tenacidade, limitação de abertura de fissuras e resistência ao impacto. A pesquisa objetiva analisar o comportamento mecânico de protótipos de tubos de concreto confeccionados com diferentes teores de adições de fibras de aço, tais como: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, em substituição total da armadura. Também foram fabricados tubos de concreto simples e armados para uma análise comparativa do comportamento mecânico entre aqueles e os tubos com fibras. Os tubos de concreto possuem 600 mm de diâmetro nominal e 1,5 m de comprimento, destinados aos sistemas de drenagem de águas pluviais. As fibras de aço utilizadas possuem fator de forma igual a 75 e apresentam as seguintes características: 60 mm de comprimento médio e 0,80 mm de diâmetro médio. Os corpos-de-prova cilíndricos foram submetidos aos ensaios: resistência à compressão axial, resistência à tração na compressão diametral, e os corpos-de- prova prismáticos foram submetidos aos ensaios de tenacidade enquanto os tubos de concreto foram submetidos aos ensaios: resistência à compressão diametral e absorção de água (amostras retiradas dos tubos após ensaio de compressão diametral). Dos ensaios realizados se destaca o ensaio de compressão diametral pelo fato... / The concrete pipe is widely used in plumbing systems in water supplying in higher diameters 400 mm, sewage, water rain drainage, storm drain and crossing. Its advantages and functions have motivated a lot of researches about this product, among them can point out used concrete pipes reinforced with steel fibers replacing the conventional framework. The steel fibers when added concrete improvement some properties, such as: flexural toughness, limitation crack width and high strain rates strength. The current text refers to a study developed to evaluate the mechanical behavior of manufactured prototypes with steel fibers added in different contents, such as: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, replacing the conventional framework. Also were manufactured simple concrete pipes and concrete pipes with framework for analysis to compare the mechanical behavior between that one and steel fibers. The pipes used have 600 mm nominal diameter and 1,5 m length, used in systems in water rain drainage. The steel fibers used have aspect ratio 75 and present characteristics: 60 mm medium length and 0,80 mm medium diameter. The circular specimens were submitted the testing for: compressive strength, tensile strength by diametrical compressive, and the rectangular specimens were submittes the testing for flexural toughness while the concrete pipes were submitted the testing for: diametrical compressive strength and absorption of water (sample retreat of pipes after the testing for diametrical compressive strength). The testing for realized to point for diametrical compressive strength because the testing for the same concrete pipe and all particular characteristics for observed. The Brazilian specification NBR 8890 (ABNT, 2007) specify the testing for diametrical compressive... (Complete abstract click electronic access below)

La finalidad de la investigación realizada en este documento es presentar el concreto reforzado con fibras de acero como alternativa de solución para la construcción de pavimento rígido. La necesidad de mejorar la calidad de los pavimentos rígidos frente a los problemas recurrentes de fisuración, optimizar costos, aumentar la calidad y optimizar los materiales para mejorar la sostenibilidad ambiental y social, impulsa el estudio e investigaciones sobre distintos aditivos que se agregan al concreto como también el tipo de refuerzo que lo complementa. Este documento se enfocará en realizar una propuesta de concretos reforzados con fibra de acero y cemento puzolánico para la construcción de pavimento rígido comparando las propiedades físicas y mecánicas de las mezclas y así obtener la mezcla más eficiente que cumpla las condiciones del expediente técnico para así realizar la aplicación en un tramo del proyecto de pavimentación en la provincia de Grau del departamento de Apurímac. / The purpose of the research carried out in this document is to present concrete reinforced with steel fibers as technical solution for the construction of concrete pavement an alternative solution for the construction of rigid pavement. In order to save costs per cubic meter per square meter of pavement and optimize raw material so increase quality and optimize materials to improve environmental and social sustainability, encourages the study and research on different chemical addition that are added to the concrete as well as the type of reinforcement that complements it. This document will focus on making a proposal of reinforced concrete with steel fiber and pozzolanic cement for the construction of rigid pavement by comparing the physical and mechanical properties of the mixtures and thus obtain the most efficient mixture that meets the conditions of the technical file in order to perform the application in a section of the paving project in the province of Grau of the department of Apurímac. / Tesis

A produção industrial do consolo tradicional apresenta dificuldades devido à grande quantidade de armadura em um espaço pequeno. Além da armadura do tirante principal, normalmente se utilizam estribos verticais e horizontais. O presente estudo experimental propõe um consolo moldado em etapa anterior à do pilar, com a armadura e superfícies preparadas para a ligação posterior com o pilar, durante a concretagem deste elemento. O consolo dispõe somente da armadura do tirante principal e de fibras metálicas incorporadas à matriz de concreto, sem estribos verticais ou horizontais. Em alguns modelos foi utilizado um tipo de armadura de costura alternativo. As principais variáveis analisadas foram a taxa de armadura e o arranjo das barras dos tirantes. A adição de fibras ao consolo reduziu a fissuração na biela de compressão e aumentou a resistência à ruptura dos consolos em 8%, apresentando boa ductilidade, mesmo depois da máxima solicitação. Com o aumento da armadura do tirante no consolo com fibras, a resistência à ruptura foi 69% maior. Considerando o patamar de solicitação de serviço do consolo tradicional, os modelos moldados em etapas distintas apresentaram aberturas de fissuras na interface consolo-pilar 33% maiores, apesar de demorarem mais a aparecer. Entretanto, quando aumentada a taxa de armadura principal, os modelos moldados em etapas distintas demonstraram fissuras 23% menores que o consolo tradicional. / The industrial production of traditional corbel presents some difficulties due to the great quantity of reinforcement in a small space. Beyond the main bars, it is generally used vertical and horizontal stirrups. This experimental study proposes a corbel shaped in the prior stage to the column, with the reinforcement and surfaces prepared to the later connection with the column during the molding of it. The corbel has only the reinforcement of main bars and steel fibers incorporated to the concrete matrix, without vertical or horizontal stirrups. In some models were used a kind of alternative secondary reinforcement. The main variables analyzed were the reinforcement rate and the arrangement of the main bars. The addition of fibers to the corbel reduced the crack in the compressed diagonal and increased the resistance to rupture of corbels in 8%, presenting a reasonable ductility even after the maximum load. With the increase of reinforcement of main bars in the corbel with fibers, the resistance to rupture was 69% greater. Considering the baseline of service load of traditional corbel, models shaped in distinct stages presented crack openings 33% larger, in spite of taking a longer time to show up. However, when the rate of primary reinforcement was increased, the models shaped in distinct stages had cracks 23% smaller than the traditional corbel.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-09-29T12:26:35Z No. of bitstreams: 1 Alessandro da Silva Nunes - 2017.pdf: 6741171 bytes, checksum: d73d33e3d451f8c04927bd5a122638d5 (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2017-09-29T16:24:11Z (GMT) No. of bitstreams: 1 Alessandro da Silva Nunes - 2017.pdf: 6741171 bytes, checksum: d73d33e3d451f8c04927bd5a122638d5 (MD5) / Made available in DSpace on 2017-09-29T16:24:11Z (GMT). No. of bitstreams: 1 Alessandro da Silva Nunes - 2017.pdf: 6741171 bytes, checksum: d73d33e3d451f8c04927bd5a122638d5 (MD5) Previous issue date: 2017-04-25 / O presente trabalho tem o objetivo de desenvolver novos materiais cerâmicos refratários, através do aproveitamento de resíduos derivados da geração de energia elétrica a partir da queima da casca de arroz. Microfibras cerâmicas foram introduzidas com o intuito de melhorar a resistência ao choque térmico. Os corpos de prova foram produzidos pelo método de prensagem uniaxial (20MPa), com substituição da argila refratária por sílica da casca de arroz (20%), e microfibras cerâmicas (20%) ou fibras de aço (1,9%, 3,8% e 5,6%). A sinterização ocorreu na temperatura de 1300º C. As propriedades físicas foram avaliadas através dos ensaios de porosidade aparente, absorção de água, densidade de massa, retração linear de queima, variação de massa e condutividade térmica. As propriedades mecânicas foram avaliadas pelos ensaios de resistência à compressão e resistência à flexão em três pontos. As propriedades térmicas foram avaliadas pelo ensaio de resistência ao choque térmico. As análises de XRD mostraram que houve transformação de parte da sílica presente na mistura em mulita e o restante permaneceu como quartzo. Além disso, a adição de sílica de casca de arroz resultou em uma microestrutura com baixa porosidade, alta retração de queima e elevada resistência mecânica. As cerâmicas com fibras apresentaram porosidade elevada, menor retração de queima e menor condutividade térmica do que a cerâmica de referência. Relativamente à resistência ao choque térmico, as cerâmicas com fibras de aço apresentaram desempenho significativamente superior em relação às cerâmicas sem fibras. / This study aims to develop new refractory ceramic materials, through the use of waste resulting from the electricity generation from rice husk burning. Ceramic microfibers were introduced with the aim of improving the resistance to thermal shock. The samples are produced by uniaxial pressing method (20MPa), by replacing refractory clay for ashes of rice husks (20%), ceramic microfibers (20%), and steel fiber (1,8%, 3,8% and 5,6%). The sintered occurred at temperature of 1300º C. Samples physical properties will be evaluated through the apparent mass density tests, apparent porosity, water absorption, linear shrinkage after burning, mass variation and thermal conductivity. The mechanical properties are evaluated by the compressive strength test and three points flexural test. The thermal properties will be evaluated by the thermal shock resistance test. XRD analyzes showed that some silica was present in the mullite mixture and the rest remained as quartz. The results show that the addition of SCA resulted in a microstructure with low porosity and with high firing shrinkage. The ceramics with fibers presented high porosity and low firing shrinkage and thermal conductivity, even, lower than the reference ceramic. The ceramics with SCA presented high mechanical resistance, while the ceramics with steel fibers had more ductile behavior. Regarding the thermal shock resistance, the ceramics with steel fibers presented a significantly superior performance in relation to the ceramics without fibers.

O Brasil necessita de uma ampla implantação de sistemas de saneamento básico, como os de águas pluviais e, principalmente, coleta e tratamento de esgoto. Para resolver este problema pode ser interessante o emprego de tubos de concreto. Apesar de recente, o estudo de tubos de concreto reforçados com fibras já possibilitou a revisão da norma brasileira NBR 8890:2007 que prevê a utilização das fibras como único reforço do componente. No entanto, apenas fibras de aço são permitidas. Apesar de terem um potencial de durabilidade maior do que os tubos convencionalmente armados, ainda há a possibilidade de ampliar sua vida útil se forem utilizadas macrofibras poliméricas, que são resistentes à corrosão eletrolítica e hoje se encontram disponibilizadas no mercado Nacional. A dúvida que permanece é se essas fibras conseguem apresentar o mesmo desempenho mecânico das fibras de aço. Assim, esta dissertação de mestrado tem por objetivo principal realizar uma avaliação comparativa de desempenho mecânico das macrofibras poliméricas e das fibras de aço destinadas ao reforço de tubos de concreto para obras de saneamento básico. De forma a possibilitar estas avaliações foi feita uma verificação de desempenho por meio do ensaio de compressão diametral, com controle de deslocamentos, em tubos de concreto reforçados com fibras. Complementarmente, foram feitos o ensaio de absorção de água, a determinação do teor de fibra incorporado ao concreto por meio de testemunhos extraídos dos tubos e o ensaio de compressão axial em corpos-de-prova moldados. Os resultados demonstraram que as macrofibras poliméricas não obtiveram desempenho mecânico satisfatório, principalmente no que se refere à resistência residual pós-fissuração do tubo. Tal desempenho só foi obtido com a utilização de fibras de aço, o qual apresentou o dobro da capacidade resistente residual das macrofibras poliméricas para o mesmo teor em volume. Dessa forma, os tubos de concreto de 1 m de diâmetro reforçado com fibras, analisados neste estudo, apresentaram dificuldade de obtenção do desempenho pós-fissuração, o que dificultou a aprovação nos critérios da NBR 8890:2007. Assim, para que estes tubos pudessem atingir as cargas especificadas nesta norma seria preciso aumentar o teor ou o comprimento das fibras, o que iria dificultar a moldagem dos tubos. / Brazil requires a wide deployment of systems for drainage and, especially, sewage collection and treatment. To resolve this issue may be interesting the use of concrete pipes. Although recent, the study of fiber reinforced concrete pipes has already enabled the revision of the Brazilian standard NBR 8890:2007. This standard allows the use of fibers as the sole reinforcement for the components. However, only steel fibers are allowed. Despite the possibility that fibers can provide a potential higher durability compared to the conventionally reinforced concrete pipes, there is also the possibility of extension of the pipe lifetime by the use of polymeric fibers. This kind of fiber is resistant to electrolytic corrosion and, nowadays, is available in the Brazilian market. The remaining doubt is if these fibers can provide the same mechanical performance of steel fibers. Thus, this work has the main objective of carried out a comparative evaluation of the mechanical performance of polymeric fibers and steel fibers reinforcement for drainage concrete pipes. In order to enable these assessments, a verification of mechanical performance was made through the crushing test, where the diametric displacement of the pipes was also measured. In addition, tests were made in order to measure the concrete water absorption, the fiber actual consumption determination in cores extracted from the pipes, and compressive strength determination. The results showed that the polymeric macrofibers did not reach satisfactory performance, especially regarding to the residual post-crack strength. Only the steel fiber reinforced concrete pipes were able to fit the requirements, which had twice the post-crack residual strength presented by the polymeric fibers with the same content by volume. Thus, the fibers reinforced concrete pipes with diameter of one meter, used in this experimental program, showed difficult to obtaining the post-cracking behavior, which turns difficult the approval in the Brazilian standard criteria. So, the pipes reinforced with polymeric fibers could only possibly reach the load levels specified for post-crack strength by the use of a higher content or an increased length of fibers, which would turns much more difficult the concrete pipes production.

In the concrete might occur cracks, due to the combination of residual stresses, cure or hydration, fluency effects, retraction and temperature effect. The objetive of incorporating steel fibers to concrete is to control the micro-cracking during aplication of loads and also improve the mechanical and residual resistance to fracturing properties . The toughness of steel fiber reinforced concrete is a fundamental property to control cracking and is determinated by flexural bending test of prismatic beams. The advantages to use SFRC in the civil construction are: better cavitation resistance, improves the strength impact plus the shock thermal and increase the ductility by delaying the crack propagation in the concrete structural elements that is subjected to the tension or tension by flexural. This study, examines experimentally the mechanicals behavior of prismatic specimens of SFRC s toughness, according to the international recommendations of ASTM C1609 (2010), EN 14651 (2007) e JSCE-SF4 (1984). On next phase, the research sought to evaluate the influence of compressive strength and the fiber rate s behavior. The experimental program consisted in two matrices of 30 MPa and 40 MPa with two dosages of fibers corresponding to 60 kg/m³ and 30 kg/m³ (0,77 % and 0,38 % in volume) formed four composite of fibers. 64 prismatic specimens were cast to evaluate the tenacity and 132 cylindrical specimens to characterize the SFRC through the compression tests, modulus of elasticity and tensile by diametric compression (Brazilian test). In relation to the method of tests, the result shows that the increasing toughness of SFRC was higher when the fiber content increased the composite compared to the change in compressive strength. The EN 14651 that uses notched specimens, it is interesting method to determine the toughness of steel fiber reinforced concrete, because the method obtained lower coefficient of variation for toughness values and the crack it always propagates in the plane of the notch. / No concreto, a fissuração poder ocorrer devido à combinação das tensões residuais em razão da cura ou hidratação, efeitos de fluência, retração e efeito da temperatura. O objetivo de incorporar as fibras de aço ao concreto é controlar a microfissuração durante o carregamento e também melhorar as propriedades mecânicas e de resistências residuais ao fraturamento. A tenacidade do concreto reforçado com fibras de aço (CRFA) é uma propriedade fundamental para controle de fissuração e é determinada com o ensaio de tenacidade à flexão de vigas prismáticas. As vantagens de se utilizar o CRFA na construção civil são: maior resistência à cavitação, melhoria da resistência ao impacto e ao choque térmico e aumento da ductilidade por atrasar a propagação da fissura nos elementos estruturais do concreto submetido à tração ou à tração na flexão. Este estudo analisa os resultados da tenacidade do CRFA, obtidos experimentalmente em corpos de prova prismáticos conforme as recomendações internacionais da ASTM C1609 (2010), EN 14651 (2007) e JSCE-SF4 (1984). Em segundo momento buscou-se avaliar a influência da resistência à compressão e o teor de fibra neste comportamento. O programa experimental consistiu em duas matrizes com fck de 30 MPa e 40 MPa e duas dosagens de fibras correspondente a 60 kg/m³ e 30 kg/m³ (0,77% e 0,38% em volume), formando quatro compósitos. Foram moldados 64 corpos de prova prismáticos para avaliar a medida de tenacidade e 132 corpos de prova cilíndricos para caracterizar o CRFA através dos ensaios de compressão, módulo de elasticidade e tração por compressão diametral. Em relação aos métodos de ensaio, os resultados indicam que o aumento de tenacidade do CRFA foi maior quando se aumentou o teor de fibra no compósito, se comparado à alteração na resistência à compressão. O método EN 14651, que utiliza corpos de prova com entalhe, é um método interessante para determinação da tenacidade de concreto reforçado com fibras de aço, pois o método obteve menor coeficiente de variação dos valores de tenacidade e a fissura sempre se propaga no plano do entalhe. / Mestre em Engenharia Civil