AVALIAÇÃO NÚMERICA DA EFICIÊNCIA DO USO DE FIBRAS DE AÇO NO PROJETO DE SEÇÕES TRANVERSAIS DE CONCRETO ARMADO NO ESTADO LIMITE ÚLTIMO

Resumo

This paper presents a numerical evaluation of the efficiency of the use of steel fibers in
reinforced concrete elements under bending with axial force in the Ultimate Limit State (ULS). The
calculation of the strength of each cross section, is an iterative method that requires the integration of
the stress in the area. This process is performed in a rigorous way using the algorithm implemented by
Ribeiro [6][7] in Java programming language. In order to present the mechanical behavior of the fiber
reinforced concrete (FRC) under tension, it is necessary to assume a constitutive law, since the use of
steel fibers provides an increase of residual strength (Model Code 2010, RILEM TC 162-TDF). The
parameters for the characterization of the compressive strength were obtained from the Brazilian
Technical Standard NBR 6118 (ABNT [8]), and the tensile constitutive law was given by
experimental results of Barros et. al. [9]. In this study, two cross sections of beams with usual
dimensions of buildings and one cross section of bridge column were used. The sections strength are
presented in the form of interaction diagrams for bending with axial forces, for fiber rates of 0 kg/m3
(without fiber), 15 kg/m3 and 30 kg/m3. The analysis of the results demonstrates an increase of the
strength as a function of the fiber content in cases that there are regions under tension.