This study analyzed the mechanical behavior of shear strength of steel fiber-reinforced concrete beams. Six beams subjected to shear loading were tested until failure. Additionally, prisms were tested to evaluate fiber contribution to the concrete shear strength. Steel fibers were straight, hook-ended, 35 mm long and aspect ratio equal to 65. Volumetric fractions used were 1.0 and 2.0%. The results demonstrated a great contribution from steel fibers to shear strength of reinforced concrete beams and to reduce crack width, which can reduce the amount of stirrups in reinforced concrete structures. Beam capacity was also evaluated by empirical equations, and it was found that these equations provided a high variability, while some of them have not properly predicted the ultimate shear strength of the steel fiber-reinforced concrete beams.

ResumoComputational modeling has become a common activity to Civil Engineering researchers and professionals. Therefore, the knowledge about the mechanical behavior of materials is very important. To correctly model the mechanical behavior of concrete structures subjected to shear stress, it is necessary to determine the shear retention factor that accounts for the friction between the two surfaces of a crack. The objective of this study is to show how the shear retention factor of steel fiber reinforced concrete can be obtained from direct shear tests associated to computational modeling. A concrete matrix with compressive strength of 60 MPa, to which 1% and 2% content of steel fibers were added, was used for the shear tests. The stress-slip relationship was obtained from these tests, and the shear retention factor of the steel fiber reinforced concrete was determined from inverse analysis using the Finite Element Method software DIANA © 8.1.2. Finally, the shear retention factor and the influence of steel fibers on the cracks were validated from the computational modeling of steel fiber reinforced concrete beams subjected to shear available in the literature. Keywords: Shear, Steel Fiber Reinforced Concrete, Computational Modeling.A modelagem computacional cada vez mais se torna parte integrante das atividades dos pesquisadores e profissionais da área de engenharia civil. Para isso, o conhecimento do comportamento mecânico dos materiais é de fundamental importância. No caso das estruturas de concreto submetidas a esforços de cisalhamento, para a correta representação do seu comportamento é necessária a determinação do fator de retenção do cisalhamento. Neste trabalho, procura-se determinar esse fator para concretos reforçados com fibras de aço por meio de ensaios de cisalhamento direto em corpos-de-prova prismáticos associados à modelagem computacional. Foi estudada, em laboratório, uma matriz de concreto com resistência à compressão de 50 MPa, à qual foram adicionadas 1,0% e 2,0% de fibras de aço. A relação tensão versus deslizamento foi determinada experimentalmente, sendo em seguida realizada uma análise inversa dos corpos-de-prova de modo a se determinar o fator de retenção do cisalhamento do concreto reforçado com fibras de aço. Para tanto, foi utilizado o programa comercial de elementos finitos DIANA © 8.1.2. Ao final, o fator de retenção do cisalhamento, bem como a influência das fibras na fissuração, foi validado por meio da modelagem de vigas de concreto armado reforçado com fibras de aço submetidas a esforços de cisalhamento disponíveis na literatura. Aço, Modelagem computacional. Palavras-chave: Cisalhamento, Concreto Reforçado com Fibras de