Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such ...Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short col- umns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.展开更多
OpenSees is a well-recognized open source platform with high compatibility,and it has a well-developed fiber element method to cope with nonlinear structural analysis.Fiber reinforced polymer(FRP)confined concrete can...OpenSees is a well-recognized open source platform with high compatibility,and it has a well-developed fiber element method to cope with nonlinear structural analysis.Fiber reinforced polymer(FRP)confined concrete can effectively improve the seismic performance of concrete structures.However,sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees.In this paper,after reviewing several typical FRP confined concrete constitutive models,a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng(2003)’s model with four main modifications including the determination of FRP rupture strain,ultimate condition,envelope shape,and hysteretic rules.To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation.Hence,the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart.Finally,with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases,FRP confinement types and geometric properties,the utility and accuracy of the proposed model compared with Lam and Teng(2003)’s model and new material secondary development in OpenSees were well validated.展开更多
The use of fibre-reinforced polymer(FRP)to confine concrete columns improves the strength and ductility of the columns by reducing passive lateral confinement pressure.Many numerical and analytical formulations have b...The use of fibre-reinforced polymer(FRP)to confine concrete columns improves the strength and ductility of the columns by reducing passive lateral confinement pressure.Many numerical and analytical formulations have been proposed in the literature to describe the compressive behaviour of FRP confined concrete under both monotonic and cyclic loads.However,the efect of a stress/strain level in the columns has not been well defined because of the lack of well-defined strategies of modeing and oversimplification of the model.This paper reviews the existing FRP combinations and the available numerical and analytical methods to determine the effectiveness of the adopted method.An effort has been made to examine the usage of FRP materials in column applications in exist-ing building regimes and highlights the possible future scopes to improve the use of FRP confined concrete in civil applications.展开更多
To better study the behavior of confined concrete, this paper presents the basic hypothesis of uhimate equilibrium of confined concrete and the unified yield criteria of confining material. Based on the static equilib...To better study the behavior of confined concrete, this paper presents the basic hypothesis of uhimate equilibrium of confined concrete and the unified yield criteria of confining material. Based on the static equilibrium condition and yield criteria of components, a unified bearing capacity model of confined concrete column is proposed, and a simplified calculating equation of the model is also given. The model captures the character of confined concrete column. Effects of the confinement effect ratio, the lateral confinement ratio, unconfined concrete strength and the properties of confining material on the bearing capacity of confined concrete column are carefully considered. The model may be applicable to the calculation of bearing capacity of steel-confined concrete, concrete filled steel tube and FRP-confined concrete. The predictions of the model agree well with test data.展开更多
The reliable prediction of hoop strain of fiber-reinforced polymer(FRP)-confined concrete is crucial for assessing confinement efficiency and ensuring structural integrity.Existing empirical models often fall short as...The reliable prediction of hoop strain of fiber-reinforced polymer(FRP)-confined concrete is crucial for assessing confinement efficiency and ensuring structural integrity.Existing empirical models often fall short as a result of idealized assumptions and limited generalizability across diverse materials and geometries.This study presents a novel,data-driven machine learning(ML)approach to estimate the effective hoop strain of FRP-confined circular concrete columns.A refined database comprising 309 experimental specimens,including Carbon,glass,and aramid FRPs,was used.Eight ML algorithms,encompassing both single(K-Nearest Neighbors,Kernel Ridge Regression,Support Vector Regression,Decision Tree)and ensemble(AdaBoost,Gradient Boosting Machine,Extreme Gradient Boosting,Random Forest)models,were trained and optimized using Optuna with 10-fold cross-validation.The top-performing models have coefficient of determination of greater than 95%as well as low residual variance and error on the full data set.Accordingly,SHapley Additive exPlanations were incorporated for global and local interpretability of the model predictions.The best-performing model was deployed in a user-friendly graphical interface,aiding an accurate and interpretable tool for practitioners.The proposed framework significantly outperforms conventional empirical models,offering a scalable solution for assessing hoop strain of FRP-confined concrete.展开更多
文摘Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short col- umns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.
基金Project supported by the National Natural Science Foundation of China(Nos.51378292,51038006,and U1134110)the China Postdoctoral Science Foundation(No.2013M530048)
文摘OpenSees is a well-recognized open source platform with high compatibility,and it has a well-developed fiber element method to cope with nonlinear structural analysis.Fiber reinforced polymer(FRP)confined concrete can effectively improve the seismic performance of concrete structures.However,sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees.In this paper,after reviewing several typical FRP confined concrete constitutive models,a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng(2003)’s model with four main modifications including the determination of FRP rupture strain,ultimate condition,envelope shape,and hysteretic rules.To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation.Hence,the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart.Finally,with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases,FRP confinement types and geometric properties,the utility and accuracy of the proposed model compared with Lam and Teng(2003)’s model and new material secondary development in OpenSees were well validated.
基金The research work presented in this paper is supported by the Foreign Young TalentsProject China(No.QN2021014006L)National Natural Science Foundation of China(Nos.51878354&51308301)+1 种基金the Natural Science Foundation of Jiangsu Province(Nos.BK20181402&BK20130978)333 Talent High-Level Projects of Jiangsu Province and Qinglan Project of Jiangsu Higher EducationInstitutions.
文摘The use of fibre-reinforced polymer(FRP)to confine concrete columns improves the strength and ductility of the columns by reducing passive lateral confinement pressure.Many numerical and analytical formulations have been proposed in the literature to describe the compressive behaviour of FRP confined concrete under both monotonic and cyclic loads.However,the efect of a stress/strain level in the columns has not been well defined because of the lack of well-defined strategies of modeing and oversimplification of the model.This paper reviews the existing FRP combinations and the available numerical and analytical methods to determine the effectiveness of the adopted method.An effort has been made to examine the usage of FRP materials in column applications in exist-ing building regimes and highlights the possible future scopes to improve the use of FRP confined concrete in civil applications.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50538060)the Excellent Young College Teacher Foundation of Anhui Prov-ince(Grant No.2009SQRZ081)
文摘To better study the behavior of confined concrete, this paper presents the basic hypothesis of uhimate equilibrium of confined concrete and the unified yield criteria of confining material. Based on the static equilibrium condition and yield criteria of components, a unified bearing capacity model of confined concrete column is proposed, and a simplified calculating equation of the model is also given. The model captures the character of confined concrete column. Effects of the confinement effect ratio, the lateral confinement ratio, unconfined concrete strength and the properties of confining material on the bearing capacity of confined concrete column are carefully considered. The model may be applicable to the calculation of bearing capacity of steel-confined concrete, concrete filled steel tube and FRP-confined concrete. The predictions of the model agree well with test data.
文摘The reliable prediction of hoop strain of fiber-reinforced polymer(FRP)-confined concrete is crucial for assessing confinement efficiency and ensuring structural integrity.Existing empirical models often fall short as a result of idealized assumptions and limited generalizability across diverse materials and geometries.This study presents a novel,data-driven machine learning(ML)approach to estimate the effective hoop strain of FRP-confined circular concrete columns.A refined database comprising 309 experimental specimens,including Carbon,glass,and aramid FRPs,was used.Eight ML algorithms,encompassing both single(K-Nearest Neighbors,Kernel Ridge Regression,Support Vector Regression,Decision Tree)and ensemble(AdaBoost,Gradient Boosting Machine,Extreme Gradient Boosting,Random Forest)models,were trained and optimized using Optuna with 10-fold cross-validation.The top-performing models have coefficient of determination of greater than 95%as well as low residual variance and error on the full data set.Accordingly,SHapley Additive exPlanations were incorporated for global and local interpretability of the model predictions.The best-performing model was deployed in a user-friendly graphical interface,aiding an accurate and interpretable tool for practitioners.The proposed framework significantly outperforms conventional empirical models,offering a scalable solution for assessing hoop strain of FRP-confined concrete.
