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J.g. Teng - One of the best experts on this subject based on the ideXlab platform.
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Advanced stress-strain model for FRP-Confined Concrete in square columns
Composites Part B: Engineering, 2020Co-Authors: Guan Lin, J.g. TengAbstract:Abstract Extensive research has been conducted on the behavior of fiber reinforced polymer (FRP)-Confined Concrete in both circular and rectangular Concrete columns. In the former columns, the stress-strain behavior of FRP-Confined Concrete is now well understood and can be closely predicted, but the same cannot be said about rectangular columns. This paper presents a new attempt at understanding and modeling the confinement mechanism in square columns as a special case of rectangular columns, leading to a new stress-strain model. The salient features of the new model include a more rigorous definition of the effective confinement area and a corner hoop strain-axial strain relationship based on advanced finite element results as well as a more reliable definition of the ultimate condition. The proposed model is analogous in approach to analysis-oriented stress-strain models for FRP-Confined Concrete in circular columns and represents a more advanced and robust method for modeling the stress-strain behavior of FRP-Confined Concrete in square columns than the existing empirically-based stress-strain models. The approach is also easily extendable to FRP-Confined Concrete in rectangular columns. The proposed model is shown to be accurate and perform better than the existing stress-strain models of the same type in predicting existing test results.
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stress strain model for frp Confined Concrete under cyclic axial compression
Engineering Structures, 2009Co-Authors: L. Lam, J.g. TengAbstract:Abstract One important application of fibre-reinforced polymer (FRP) composites in construction is as FRP jackets to confine Concrete in the seismic retrofit of reinforced Concrete (RC) structures, because FRP confinement can enhance both the compressive strength and ultimate strain of Concrete. For the safe and economic design of FRP jackets, the stress–strain behaviour of FRP-Confined Concrete under cyclic compression needs to be properly understood and modelled. This paper presents a stress–strain model for FRP-Confined Concrete under cyclic axial compression. The model consists of the following major components: (a) a monotonic stress–strain model for FRP-Confined Concrete developed by the authors in a previous study for predicting the envelope curve; (b) new algebraic expressions for predicting unloading and reloading paths; and (c) predictive equations for determining the permanent strain and stress deterioration, with the effect of loading history duly accounted for. The capability and accuracy of the proposed model in predicting the complete stress–strain history of FRP-Confined Concrete under cyclic axial compression are demonstrated through comparisons between predictions of the proposed model and test results.
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Stress–strain model for FRP-Confined Concrete under cyclic axial compression
Engineering Structures, 2009Co-Authors: L. Lam, J.g. TengAbstract:Abstract One important application of fibre-reinforced polymer (FRP) composites in construction is as FRP jackets to confine Concrete in the seismic retrofit of reinforced Concrete (RC) structures, because FRP confinement can enhance both the compressive strength and ultimate strain of Concrete. For the safe and economic design of FRP jackets, the stress–strain behaviour of FRP-Confined Concrete under cyclic compression needs to be properly understood and modelled. This paper presents a stress–strain model for FRP-Confined Concrete under cyclic axial compression. The model consists of the following major components: (a) a monotonic stress–strain model for FRP-Confined Concrete developed by the authors in a previous study for predicting the envelope curve; (b) new algebraic expressions for predicting unloading and reloading paths; and (c) predictive equations for determining the permanent strain and stress deterioration, with the effect of loading history duly accounted for. The capability and accuracy of the proposed model in predicting the complete stress–strain history of FRP-Confined Concrete under cyclic axial compression are demonstrated through comparisons between predictions of the proposed model and test results.
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Ultimate axial strain of FRP-Confined Concrete
Advances in Building Technology, 2007Co-Authors: L. Lam, J.g. TengAbstract:Publisher Summary External confinement by the wrapping of FRP sheets (or FRP jacketing) provides a very effective method for the retrofit of reinforced Concrete columns subject to either static or seismic loads. For the reliable and cost-effective design of FRP jackets, an accurate stress-strain model is required for FRP-Confined Concrete. The determination of the ultimate condition of FRP-Confined Concrete, which is reached when the FRP ruptures, is the core of model. This ultimate condition is characterized by two parameters—the ultimate axial strain and the corresponding stress level, which may or may not be the ultimate strength of the FRP-Confined Concrete. This chapter presents a new equation for the ultimate axial strain of FRP-Confined Concrete on which there has been much uncertainty. It finally presents the Confined cylinder tests as a standard type of tests to determine the efficiency factor of a particular FRP product in confinement applications, defined as the ratio between the actual hoop rupture strain of FRP in FRP-Confined Concrete and the ultimate tensile strain from material tests generally conducted using flat coupons.
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Analysis-oriented stress–strain models for FRP–Confined Concrete
Engineering Structures, 2007Co-Authors: T Jiang, J.g. TengAbstract:Abstract Many stress–strain models have been developed for fibre-reinforced polymer (FRP)–Confined Concrete. These models fall into two categories: (a) design-oriented models in simple closed-form expressions for direct use in design; and (b) analysis-oriented models in which the stress–strain curve is generated via an incremental process. This paper is concerned with analysis-oriented models, and in particular, those models based on the commonly accepted approach in which a model for actively-Confined Concrete is used as the base model. The paper first provides a critical review and assessment of existing analysis-oriented models for FRP–Confined Concrete. For this assessment, a database of 48 recent tests conducted by the authors’ group is presented; this database includes 23 new tests which have not previously been published. This assessment clarifies how each of the key elements forming such a model affects its accuracy and identifies a recent model proposed by the authors’ group as being the most accurate. The paper then presents a refined version of this model, which provides more accurate predictions of the stress–strain behaviour, particularly for weakly-Confined Concrete.
Chris P. Pantelides - One of the best experts on this subject based on the ideXlab platform.
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Mohr-coulomb model for rectangular and square FRP-Confined Concrete
Composite Structures, 2019Co-Authors: Domingo A. Moran, Chris P. Pantelides, Lawrence D. ReaveleyAbstract:Abstract An analytical stress-strain model for fiber reinforced polymer (FRP) Confined Concrete is developed for predicting the compressive and dilation behavior of rectangular and square cross-sections with rounded corners. An iterative as well as a non-iterative two parameter Mohr-Coulomb yield criterion are introduced for analyzing the compressive behavior of FRP-Confined Concrete. A new diagonal Poisson’s ratio formulation is employed which describes the dilation behavior of FRP-Confined Concrete as a function of the mechanical properties of unConfined Concrete, FRP jacket, section geometry, and internal damage of the Confined Concrete core. Equilibrium and strain compatibility are used to obtain the ultimate Concrete compressive strength and strain as a function of the effective confining stiffness of the FRP jacket and transverse strains. Simplified expressions are derived for the FRP reinforcement ratio which precludes strain-softening in rectangular and square FRP-Confined Concrete sections.
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Elliptical and circular FRP-Confined Concrete sections: A Mohr–Coulomb analytical model
International Journal of Solids and Structures, 2012Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:Abstract An analytical stress–strain model is developed for predicting the compressive behavior of elliptical and circular fiber reinforced polymer (FRP)-Confined Concrete members. The model is based on a diagonal Poisson’s ratio formulation expressed as a function of the mechanical properties of the unConfined Concrete and confining FRP jacket, the geometry of the Concrete section, and the extent of internal damage in the Confined Concrete core. A Mohr–Coulomb yield criterion is introduced for analysis of the compressive behavior of Confined Concrete. Equilibrium and strain compatibility are used to obtain the ultimate compressive strength and strain of elliptical and circular FRP-Confined Concrete sections as a function of the effective confining stiffness of the FRP jacket. A simplified expression is derived for the FRP reinforcement ratio which precludes strain softening in elliptical and circular FRP-Confined Concrete sections.
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Damage-based stress-strain model for fiber-reinforced polymer-Confined Concrete
ACI Structural Journal, 2005Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:Fiber-reinforced polymer (FRP) composite jackets can be used to retrofit existing reinforced Concrete columns and structural systems. This article presents a damage-based stress-strain model applicable for both bonded or nonbonded FRP Confined Concrete. The model was developed for predicting the compressive behavior of circular FRP-Confined Concrete members and is based on a variable of Poisson's ratio formulation. The general concepts of elasticity, damage mechanics, and plasticity theory are included in this stress-strain model that considers the macrostructural effects of the increase in internal damage into a simple mechanics model. Poisson's ratios used in the model are a function of the mechanical properties of the unConfined Concrete and confining FRP jacket, and the extent of internal damage in the Confined Concrete core. The authors conclude that the proposed damage-based stress-strain model governs the behavior of circular FRP-Confined Concrete throughout its compressive behavior and can be easily implemented into a spreadsheet, finite element, or other computer language program for the analysis of FRP-Confined Concrete members.
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Stress-strain model for fiber-reinforced polymer-Confined Concrete
Journal of Composites for Construction, 2002Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:The design of fiber-reinforced polymer (FRP)-Confined Concrete members requires accurate evaluation of the performance enhancement due to the confinement provided by FRP composite jackets. A strain ductility-based model is developed for predicting the compressive behavior of normal strength Concrete Confined with FRP composite jackets. The model is applicable to both bonded and nonbonded FRP-Confined Concrete and can be separated into two components: a strain-softening component, which accounts for unrestrained internal crack propagation in the Concrete core, and a strain-hardening component, which accounts for strength increase due to confinement provided by the FRP composite jacket. A variable strain ductility ratio described in a companion paper is used to develop the proposed stress-strain model. Equilibrium and strain compatibility are used to obtain the ultimate compressive strength and strain of FRP-Confined Concrete as a function of the confining stiffness and ultimate strain of the FRP jacket.
Domingo A. Moran - One of the best experts on this subject based on the ideXlab platform.
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Mohr-coulomb model for rectangular and square FRP-Confined Concrete
Composite Structures, 2019Co-Authors: Domingo A. Moran, Chris P. Pantelides, Lawrence D. ReaveleyAbstract:Abstract An analytical stress-strain model for fiber reinforced polymer (FRP) Confined Concrete is developed for predicting the compressive and dilation behavior of rectangular and square cross-sections with rounded corners. An iterative as well as a non-iterative two parameter Mohr-Coulomb yield criterion are introduced for analyzing the compressive behavior of FRP-Confined Concrete. A new diagonal Poisson’s ratio formulation is employed which describes the dilation behavior of FRP-Confined Concrete as a function of the mechanical properties of unConfined Concrete, FRP jacket, section geometry, and internal damage of the Confined Concrete core. Equilibrium and strain compatibility are used to obtain the ultimate Concrete compressive strength and strain as a function of the effective confining stiffness of the FRP jacket and transverse strains. Simplified expressions are derived for the FRP reinforcement ratio which precludes strain-softening in rectangular and square FRP-Confined Concrete sections.
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Elliptical and circular FRP-Confined Concrete sections: A Mohr–Coulomb analytical model
International Journal of Solids and Structures, 2012Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:Abstract An analytical stress–strain model is developed for predicting the compressive behavior of elliptical and circular fiber reinforced polymer (FRP)-Confined Concrete members. The model is based on a diagonal Poisson’s ratio formulation expressed as a function of the mechanical properties of the unConfined Concrete and confining FRP jacket, the geometry of the Concrete section, and the extent of internal damage in the Confined Concrete core. A Mohr–Coulomb yield criterion is introduced for analysis of the compressive behavior of Confined Concrete. Equilibrium and strain compatibility are used to obtain the ultimate compressive strength and strain of elliptical and circular FRP-Confined Concrete sections as a function of the effective confining stiffness of the FRP jacket. A simplified expression is derived for the FRP reinforcement ratio which precludes strain softening in elliptical and circular FRP-Confined Concrete sections.
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Damage-based stress-strain model for fiber-reinforced polymer-Confined Concrete
ACI Structural Journal, 2005Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:Fiber-reinforced polymer (FRP) composite jackets can be used to retrofit existing reinforced Concrete columns and structural systems. This article presents a damage-based stress-strain model applicable for both bonded or nonbonded FRP Confined Concrete. The model was developed for predicting the compressive behavior of circular FRP-Confined Concrete members and is based on a variable of Poisson's ratio formulation. The general concepts of elasticity, damage mechanics, and plasticity theory are included in this stress-strain model that considers the macrostructural effects of the increase in internal damage into a simple mechanics model. Poisson's ratios used in the model are a function of the mechanical properties of the unConfined Concrete and confining FRP jacket, and the extent of internal damage in the Confined Concrete core. The authors conclude that the proposed damage-based stress-strain model governs the behavior of circular FRP-Confined Concrete throughout its compressive behavior and can be easily implemented into a spreadsheet, finite element, or other computer language program for the analysis of FRP-Confined Concrete members.
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Stress-strain model for fiber-reinforced polymer-Confined Concrete
Journal of Composites for Construction, 2002Co-Authors: Domingo A. Moran, Chris P. PantelidesAbstract:The design of fiber-reinforced polymer (FRP)-Confined Concrete members requires accurate evaluation of the performance enhancement due to the confinement provided by FRP composite jackets. A strain ductility-based model is developed for predicting the compressive behavior of normal strength Concrete Confined with FRP composite jackets. The model is applicable to both bonded and nonbonded FRP-Confined Concrete and can be separated into two components: a strain-softening component, which accounts for unrestrained internal crack propagation in the Concrete core, and a strain-hardening component, which accounts for strength increase due to confinement provided by the FRP composite jacket. A variable strain ductility ratio described in a companion paper is used to develop the proposed stress-strain model. Equilibrium and strain compatibility are used to obtain the ultimate compressive strength and strain of FRP-Confined Concrete as a function of the confining stiffness and ultimate strain of the FRP jacket.
Kilhee Kim - One of the best experts on this subject based on the ideXlab platform.
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prediction of stress strain behavior of spirally Confined Concrete considering lateral expansion
Construction and Building Materials, 2016Co-Authors: Youngseek Kim, Sangwoo Kim, Jungyoon Lee, Jaeman Lee, Hyeonggook Kim, Kilhee KimAbstract:Abstract This paper proposes a new analytical model for the relationship between the axial and transverse strains of Confined Concrete in uniaxial compression. The proposed model was developed based on empirical data for a circular section Confined by spirals. A column with a circular section and subjected to uniaxial compression was considered. The proposed model predicts the stress in the transverse confinement reinforcement to estimate the relationship between the axial strain of the column and tensile strain of the transverse confinement reinforcement. The model can also produce the axial stress–strain relationship of the Confined Concrete of the column. The predicted axial and transverse strains of the Confined Concrete section corresponded to the observed axial peak stress of a column evaluated in previous research with good accuracy. This model will be an effective tool for investigating the effect of circular spirals on the structural behavior of Confined Concrete and enhancing the accuracy of structural behavior analysis for a column under uniaxial compression.
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Prediction of stress–strain behavior of spirally Confined Concrete considering lateral expansion
Construction and Building Materials, 2016Co-Authors: Youngseek Kim, Sangwoo Kim, Jungyoon Lee, Jaeman Lee, Hyeonggook Kim, Kilhee KimAbstract:Abstract This paper proposes a new analytical model for the relationship between the axial and transverse strains of Confined Concrete in uniaxial compression. The proposed model was developed based on empirical data for a circular section Confined by spirals. A column with a circular section and subjected to uniaxial compression was considered. The proposed model predicts the stress in the transverse confinement reinforcement to estimate the relationship between the axial strain of the column and tensile strain of the transverse confinement reinforcement. The model can also produce the axial stress–strain relationship of the Confined Concrete of the column. The predicted axial and transverse strains of the Confined Concrete section corresponded to the observed axial peak stress of a column evaluated in previous research with good accuracy. This model will be an effective tool for investigating the effect of circular spirals on the structural behavior of Confined Concrete and enhancing the accuracy of structural behavior analysis for a column under uniaxial compression.
Guan Lin - One of the best experts on this subject based on the ideXlab platform.
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Advanced stress-strain model for FRP-Confined Concrete in square columns
Composites Part B: Engineering, 2020Co-Authors: Guan Lin, J.g. TengAbstract:Abstract Extensive research has been conducted on the behavior of fiber reinforced polymer (FRP)-Confined Concrete in both circular and rectangular Concrete columns. In the former columns, the stress-strain behavior of FRP-Confined Concrete is now well understood and can be closely predicted, but the same cannot be said about rectangular columns. This paper presents a new attempt at understanding and modeling the confinement mechanism in square columns as a special case of rectangular columns, leading to a new stress-strain model. The salient features of the new model include a more rigorous definition of the effective confinement area and a corner hoop strain-axial strain relationship based on advanced finite element results as well as a more reliable definition of the ultimate condition. The proposed model is analogous in approach to analysis-oriented stress-strain models for FRP-Confined Concrete in circular columns and represents a more advanced and robust method for modeling the stress-strain behavior of FRP-Confined Concrete in square columns than the existing empirically-based stress-strain models. The approach is also easily extendable to FRP-Confined Concrete in rectangular columns. The proposed model is shown to be accurate and perform better than the existing stress-strain models of the same type in predicting existing test results.