Numerical Investigation of Tension Behavior of Reinforced Concrete Members Strengthened with FRP Sheets (original) (raw)
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Tension-Stiffening Model for Steel Fiber-Reinforced Concrete Containing Conventional Reinforcement
ACI Structural Journal, 2013
The tensile behavior of fiber-reinforced concrete (FRC) members co-reinforced with conventional deformed reinforcing bar (R/FRC members) is analytically investigated in regards to tensile stresses developed in the reinforcing bars, tensile stresses induced in the steel fibers bridging a crack, and the bond mechanism between the reinforcing bar and the concrete matrix. A tension-stiffening model for R/FRC members is developed through an analytical parametric study using a crack analysis procedure that considers the tensile behavior due to the steel fibers and the bond stress-slip relationship between the reinforcing bar and the concrete matrix. With the proposed model, the local yielding of reinforcing bars at a crack can be realistically simulated, enabling reasonably accurate predictions of the tensile behavior of R/FRC members. Analysis results obtained from the proposed model show good agreement with the test results measured by previous researchers.
The tensile contribution of concrete, known as tension stiffening, is usually neglected when calculating the strength of reinforced concrete (RC) members. However, tension stiffening affects the post-cracking stiffness and consequently the overall behavior in terms of deflection and crack width of the member under service load. There have been many investigations conducted on the tension stiffening effect in RC members, but very few on Fiber Reinforced Polymer (FRP) RC members. This paper presents the results of a study of the tension stiffening in FRP RC members based on 12 full-scale tensile tests. The results indicate that the presence of the externally bonded FRP material typically alters the main characteristics of the stress-strain relationships of concrete in tension and associated crack patterns.
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Based on the characterization of the bond between Fiber-Reinforced Polymer (FRP) bars and concrete, the structural behavior of cracked Glass-FRP (GFRP)-Reinforced Concrete (RC) tensile elements is studied in this paper. Simulations in which different bond-slip laws between both materials (FRP reinforcement and concrete) were used to analyze the effect of GFRP bar bond performance on the load transfer process and how it affects the load-mean strain curve, the distribution of reinforcement strain, the distribution of slip between reinforcement and concrete, and the tension stiffening effect. Additionally, a parametric study on the effect of materials (concrete grade, modulus of elasticity of the reinforcing bar, surface configuration, and reinforcement ratio) on the load-mean strain curve and the tension stiffening effect was also performed. Results from a previous experimental program, in combination with additional results obtained from Finite Element Analysis (FEA), were used to de...
The Role of the Bond on the Structural Behaviour of Flexural FRP Reinforced Concrete Members
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The paper focuses on the bond between fibre-reinforced polymer (FRP) reinforcements and concrete including its modelling (local bond-slip law) and influence on the structural behaviour of FRP reinforced concrete members. The analysis, both theoretical and experimental, refers to flexural concrete beams upgraded by externally bonded FRP sheets, considering different bonding systems such as the commonly used resin-FRP system and novel bonding technologies (near surface mounted system, cementitious-FRP system). The structural behaviour of strengthened beams is analyzed by means of a non linear model derived from a cracking analysis based on slip and bond stress. By using some bond-slip models, the performances of beams under service conditions (cracking, deformability) are evaluated varying parameters governing the FRP-to-concrete bond behaviour. Results of the analysis furnish useful information to find interface bonding systems which can offer suitable bond characteristics to optimize the performances of FRP reinforced concrete members.
Analytical Modeling of Concrete Beams Reinforced with Carbon FRP Bars
Journal of Composite Materials, 2007
A non-linear finite element model is presented for the analysis of simply supported reinforced concrete beams. Cracked concrete is considered as an orthotropic material and the crack formation is simulated as smeared cracks. A rotating crack method is employed based on the total strain crack model. The analysis was carried out with the help of 2D isoparametric plane stress elements. Compression and tension softening and tension stiffening effects of the cracked concrete were considered. The tension reinforcement consisted of either steel or fiber reinforced polymer (FRP) bars. Excellent convergence and numerical stability of the formulation was found. The model showed good agreement with the recorded data of the tested beams.