Axial compressive behavior of FRP-confined concrete: Experimental test database and a new design-oriented model
TL;DR: In this article, the authors present a comprehensive test database constructed from the results of axial compression tests on 832 circular FRP-confined concrete specimens published in the literature.
Abstract: A large number of experimental studies have been conducted over the last two decades to understand the behavior of FRP-confined concrete columns. This paper presents a comprehensive test database constructed from the results of axial compression tests on 832 circular FRP-confined concrete specimens published in the literature. The database was assembled through an extensive review of the literature that covered 3042 test results from 253 experimental studies published between 1991 and the middle of 2013. The suitability of the results for the database was determined using carefully chosen selection criteria to ensure a reliable database. This database brings reliable test results of FRP-confined concrete together to form a unified framework for future reference. Close examination of the test results reported in the database led to a number of important observations on the influence of important parameters on the behavior of FRP-confined concrete. A new design-oriented model that was developed to quantify these observations is presented in the final part of the paper. It is shown that the predictions of the proposed model are in close agreement with the test results and the model provides improved predictions of the ultimate conditions of FRP-confined concrete compared to any of the existing models.
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TL;DR: In this paper, the axial compressive behavior of fiber-reinforced polymer (FRP) composites for high-strength concrete (HSC) has been investigated.
Abstract: It is well understood that confining concrete with fiber-reinforced polymer (FRP) composites can significantly enhance its strength and deformability However, the confinement demand of concrete increases proportionally with its strength, resulting in higher confinement requirements for high-strength concrete (HSC) This paper reports on a study on the axial compressive behavior of FRP-confined HSC A large experimental test database, which consists of 237 axial compression tests results for FRP-confined HSC, was assembled from the published literature and presented in this paper This database was augmented with another database of FRP-confined normal-strength concrete (NSC), which consists of 739 test results The combined database of 1063 test results, which cover specimens with unconfined concrete strengths ranging from 62 to 1697 MPa, was used to investigate and quantify the factors that influence the compressive behavior of FRP-confined HSC Analysis of the test results reported in the dat
202 citations
TL;DR: In this article, a unified confinement model for unconfined and confined concretes was developed to predict the peak and residual conditions and the complete stress-strain behavior of unconfining and actively confined concrete.
183 citations
TL;DR: In this article, a generic model was proposed to describe the lateral strain-to-axial strain relationship of confined concrete, based on a large number of experimental test results of both fiber-reinforced polymers (FRP) confined and actively confined concretes.
Abstract: The use of fiber-reinforced polymers (FRP) has become widely accepted engineering practice for strengthening reinforced concrete members. It is well established that lateral confinement of concrete with FRP composites can significantly enhance its strength and ductility. As the confinement pressure generated by FRP on the confined concrete depends on the lateral expansion of concrete, the mechanism of concrete expansion inside the FRP shell is of significant interest. A review of the existing stress-strain models of FRP-confined concrete revealed the need for a model that accurately predicts the dilation characteristic of confined concrete as it provides the essential link between the response of the concrete core and the passive confinement mechanism of the FRP shell. It is also understood that knowledge established from the research area of actively confined concrete can be employed in the development of a model applicable for both FRP-confined and actively confined concretes. Based on a large number of experimental test results of both FRP-confined and actively confined concretes, a generic model is proposed to describe the lateral strain-to-axial strain relationship of confined concrete. The instrumentation arrangements of the tested specimens have allowed for the lateral strain-axial strain relationships of confined concrete to be captured throughout the tests. The trend of the lateral strain-to-axial strain relationship of confined concrete is shown to be a function of the confining pressure, type of confining material and concrete strength. Assessment of models with the experimental databases showed that the predictions of the proposed model are well above existing models and in good agreement with the test results of both FRP-confined and actively confined concretes.
125 citations
TL;DR: A new and general stress-strain model for concrete confined by steel or fiber reinforced polymer (FRP) is developed in this article, where one additional variable and one constant are added to the well-known Popovics model to control the type and the shape of the stress curve.
Abstract: A new and general stress-strain model for concrete confined by steel or fiber reinforced polymer (FRP) is developed in this work. One additional variable and one constant are added to the well-known Popovics model to control the type and the shape of the stress-strain curve. The proposed model has one simple, continuous, and explicit expression and can exhibit either hardening or softening types of responses. This general model provides a unified platform for modeling stress-strain of concrete confined by different materials, such as steel or FRP, and help to overcome inconsistency or complexity. The parameters of the stress-strain model are determined by analytical study and data regression using a large and up-to-date test database. The proposed stress-strain model is validated with experimental results and compared with existing models; it shows good performance and superior flexibility and versatility of the model.
121 citations
TL;DR: In this article, the axial compressive behavior of steel fiber reinforced high-strength concrete (SFRHSC)-filled FRP tubes was investigated under axial compression and axial stress-strain behavior of CFFTs was analyzed.
120 citations
Cites background or result from "Axial compressive behavior of FRP-c..."
...A similar observation was reported in a number of recent studies, where the differences in strains were explained by the cracking behavior of the concrete and it was shown how the increased brittleness of concrete resulted in lower MLVDT/FLVDT ratios [1,37]....
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...[1–4] illustrated the great number of studies that have been undertaken on the topic to investigate the axial compressive behavior of both FRP-wrapped concrete columns (e....
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References
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TL;DR: In this paper, a new design-oriented stress-strain model is proposed for concrete confined by FRP wraps with fibres only or predominantly in the hoop direction based on a careful interpretation of existing test data and observations.
1,161 citations
"Axial compressive behavior of FRP-c..." refers background or methods or result in this paper
...Lam and Teng [3] then defined a term called the actual confining pressure (flu,a) (Eq....
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...material (εf or εfrp), in addition to the confinement ratio (flu,a / f'co), as was pointed out in a number of previous studies [3, 18, 37, 39]....
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...The earlier databases reported by Lam and Teng [2, 3], De Lorenzis and Tepfers [4] and Bisby et al. [5] are extensive and include the majority of the experimental data with sufficient detail that were available at the time the databases were published....
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...As reported originally in Lam and Teng [3], hoop strains measured within the overlap regions of the...
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...Previously, both Mirmiran et al. [9] and Lam and Teng [2] reported that there was no significant difference between the behaviors of FRP-wrapped and FRP tube-encased concrete specimens....
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TL;DR: In this paper, axial compression test results of 27 concrete cylinders confined by carbon fiber reinforced polymer composite jackets were described, and the failure of the confined concrete was dominated by the rupture of the jacket at an average strain much smaller than the ultimate strain obtained from tension tests of flat coupons.
Abstract: This paper describes axial compression test results of 27 concrete cylinders confined by carbon fiber reinforced polymer composite jackets. The experimental parameters include plain concrete compressive strength and the thickness of the composite jacket. It is found that the carbon fiber composite jacketing can significantly increase the compressive strength and ductility of concrete. The test results indicate that concrete strength and confinement modulus, defined as the ratio of transverse confinement stress and transverse strain, are the most influential factors affecting the stress-strain behavior of confined concrete. The failure of the confined concrete was dominated by the rupture of the jacket at an average strain much smaller than the ultimate strain obtained from tension tests of flat coupons. In order to describe the main mechanical features of the confined concrete, a simple bilinear stress-strain model is suggested based on the theory of elasticity and minimum number of empirical equations de...
661 citations
TL;DR: In this article, the effect of shape, length, and bond on FRP-confined concrete columns is studied and a modified confinement ratio that is a function of the corner radius and the jacket's hoop strength is calculated.
Abstract: Confinement effectiveness of fiber reinforced plastic (FRP) jackets (shells) in concrete columns depends on several parameters, including concrete strength, types of fibers and resin, fiber volume and fiber orientation in the jacket, jacket thickness, shape of cross section, length-to-diameter (slenderness) ratio of the column, and the interface bond between the core and the jacket. In this paper effects of shape, length, and bond on FRP-confined concrete are studied. Square sections are shown to be less effective in confining concrete than their circular counterparts. Their effectiveness is measured by a modified confinement ratio that is a function of the corner radius and the jacket's hoop strength. Length effect in short columns of up to 5:1 is shown to be similar to ACI provisions for tied columns, i.e., 10% eccentricity and 20% strength reduction in pure compression. While chemical adhesive bond does not change the confinement effectiveness of the jacket, mechanical shear connectors can enhance the ...
620 citations
"Axial compressive behavior of FRP-c..." refers background in this paper
...[9] and Lam and Teng [2] reported that there was no significant difference between...
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TL;DR: In this article, a critical review and assessment of existing analysis-oriented models for FRP-confined concrete is presented; this database includes 23 new tests which have not previously been published.
507 citations
"Axial compressive behavior of FRP-c..." refers methods in this paper
...the studies [18, 28-36] the elastic moduli (Efrp) and tensile stresses (ffrp) were calculated based on nominal fiber thickness instead of the measured thickness of flat FRP coupons....
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