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    Elastoplastic Finite-Element Analysis of FRP-Confined Masonry Columns
    (Asce-Amer Soc Civil Engineers, 2012) Koksal, H. O.; Aktan, S.; Kuruscu, A. O.
    The focus of the work described in this paper is on the development of a practical Drucker-Prager (DP) type constitutive model for the nonlinear finite-element analysis (NLFEA) of fiber-reinforced polymers (FRP)-confined masonry columns under concentric compression. This paper introduces analytical relations for the cohesion and internal friction angle for masonry constituents, i.e., solid clay bricks and mortar. The proposed relations account for the slight change of the linear part of the compressive meridian into a curve at higher hydrostatic pressure values and predict the compressive and tension meridians of concrete even for high hydrostatic pressure. Evaluating possible failure criteria in FRP-confined masonry columns, 14 test specimens from three major experimental studies are successively modeled through the proposed approach. The results of NLFEA show both satisfactory predictions of the stress-strain response of the columns and theoretical understanding for the strain distributions in the FRP sheets. DOI: 10.1061/(ASCE)CC.1943-5614.0000268. (C) 2012 American Society of Civil Engineers.
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    Öğe
    Uncertainty Definition on the Constitutive Models for RC Columns Wrapped with FRP
    (Springer Heidelberg, 2014) Doran, B.; Erdolen, A.; Akbas, B.; Kutug, Z.; Koksal, H. O.
    This paper aims to explore the effectiveness of the fiber-reinforced polymer (FRP)-confining mechanism in concrete in which parameters are uncertain. The confinement effect of high stiffness FRP jackets results an increase in the compressive strength of reinforced concrete columns and should be clearly defined. Various constitutive models have been constructed to predict the mechanical behavior of FRP-wrapped columns by considering this effect. However, the mechanical response of confined concrete columns due to FRP jackets under concentric compression has still been a challenging issue, and there are still some uncertainties in mechanical and also geometrical properties in the analysis and design procedure. These uncertainties can be studied with interval analysis (IA) to determine sharp bounds of the mechanical parameters such as effective lateral confining stress, Young's modulus of concrete and FRP, and geometrical parameters. For this purpose, an IA has been performed using deterministic values of compressive strength for significant number (163) of experimental data being reported by several researchers on FRP-confined square/rectangular columns. The results indicate that uncertainties in material parameters and compressive strengths play an important role in determining the lateral stresses of FRP-confined columns.