ON THE FINITE ELEMENT MODELING OF RC BEAMS SHEAR-STRENGTHENED USING NSM-FRP

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Abstract

Application of near-surface mounted (NSM) fiber reinforced polymer (FRP) is emerging as a promising technology for increasing shear strength of reinforced concrete (RC) members. However, most of studies in this field, have been performed experimentally and only very limited research is available on the numerical modeling of such beams using finite element (FE) method. This paper presents the results of a recent study in which a FE procedure was proposed to investigate the effects of conventional numerical modeling assumptions. In such methods, interfaces between concrete and steel stirrups and between concrete and FRP are not considered to predict the behavior of RC beams shear-strengthened with NSM-FRP. Despite the widespread use of these assumptions in numerical modeling of RC beams, their deficiencies and limitations have not been investigated in depth yet. Therefore, this paper presents a critical study on the FE modeling of NSM-FRP shear strengthened RC beams. For this aim, numerical modeling was carried out for two major groups of test beams. In the first group, specimens were selected from available experimental programs published in literature. For the second group, modeling was performed on three rectangular beams, built and tested in structural laboratory by cooperating of authors. Numerical results were compared by experimental findings. The load deflection response obtained from the proposed numerical method showed good agreement with the experimental plots. In some cases, such as cracking pattern and strain distribution in FRP and steel reinforcement, undesirable discrepancies were observed between FE and experiments. Maximum strain ratio between FE and experiments was reported in 0.66 to 0.89 for FRP and in 0.25 to 0.60 for steel stirrups.

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