Stress–Strain Relation of FRP-Confined Predamaged Concrete Prisms with Square Sections of Different Corner Radii Subjected to Monotonic Axial Compression

The energy balance method has been widely used in the extant literature to derive the ultimate axial strain of conventional confined concrete columns. However, researchers noted that this method yields unrealistic results compared to experimental data when it is applied to fiber-reinforced polymer (FRP) confined concrete columns. Therefore, it is deemed that the existing ultimate strain model based on the energy method cannot be directly applied to FRP-repaired concrete. With this model shortcoming in mind and through a theoretical analysis with proper calibration, the current study extended the energy balance approach to develop a generalized model to determine the ultimate strain of FRP repaired concrete columns. This proposed new model can be used to predict the ultimate strain of repaired columns under both concentric and eccentric loadings. Because this model is established in a unified form without any restrictions to the cross-sectional geometry, it is applicable to different shapes of repaired columns. On the other hand, although the energy balance method is unconservative for heavily damaged concrete, it exhibits a better performance with respect to the existing models when compared with the test result. K E Y W O R D Sconcrete structure, confinement, energy method, FRP, repairing, ultimate strain

“…The ultimate strength

{\overset{false˜}{f}}_{cu}

in Equation can be calculated using an existing model. The model of Wu et al modified by Li et al is adopted in this work, as:

\frac{{\overset{f}{true}}_{italiccu}}{f_{italicco}} = 1 + 3.9 {(\frac{f_{l}}{f_{italicco}})}^{1.13} {(\frac{2 r}{b})}^{0.67} - δ,

Section: Ultimate Strain Of Frp‐repaired Concrete Under Concentric Lomentioning

confidence: 99%

Section: Ultimate Strain Of Frp‐repaired Concrete Under Concentric Lomentioning

confidence: 99%

Section: Ultimate Strain Of Frp‐repaired Concrete Under Concentric Lomentioning

confidence: 99%

Section: Ultimate Strain Of Frp‐repaired Concrete Under Concentric Lomentioning

confidence: 99%

“…The existing models and the proposed model in Equation are evaluated with the test database summarized in Tables and . Equations are used to evaluate the performance of the models.…”

Section: Ultimate Strain Of Frp‐repaired Concrete Under Concentric Lomentioning

confidence: 99%

See 3 more Smart Citations

Energy balance method for modeling ultimate strain of fiber‐reinforced polymer‐repaired concrete

Tijani

Lim

2019

Effects of predamage and load cyclic on compression behavior of fiber reinforced polymer‐confined concrete

Cao

Hou

Liu

et al. 2021

Most existing studies on fiber reinforced polymer (FRP) confined concrete have focused on undamaged concrete that is subjected to uniaxial monotonic compression. However, FRP jackets are usually applied to concrete columns with existing material damage and potential future damage. This paper investigates FRP confinement on concrete with damage before and after FRP jacketing. A total of 32 FRP‐confined concrete specimens were tested under axial compression in this work. The prior damage before FRP jacketing was implemented as predamaging by applying preloading and then release on the plain concrete specimens. The post damage after FRP jacketing was performed by applying cyclic axial compression loading on FRP‐confined concrete specimens. The test results reveal that the concrete predamage levels have significant influences on the cyclic stress–strain curve and envelop stress–strain curve for FRP confined concrete under cyclic loading. Existing models on ultimate state, plastic strain, reloading and unloading moduli were evaluated and investigated in this work.

Experimental study on the eccentric performances of high predamaged rectangular reinforced concrete columns strengthened with carbon fiber reinforced polymer

Zou

Fang

et al. 2022

The mechanical behaviors of 12 high predamaged reinforced concrete (RC) rectangular columns strengthened with carbon fiber reinforced polymer (CFRP) under eccentric compression were experimentally investigated. The effects of the predamaged degree (δ), CFRP strips spacing (s f ) and eccentricity (e) on failure mode, bearing capacity, strain behaviors of CFRP strengthened predamaged columns were examined systematically. Test results demonstrated that the strengthened RC columns with small-eccentricity were destroyed by the yielding of compressive longitudinal steel bars and the crushing of compression concrete while the transverse CFRP strips were not ruptured. The failure mode of the strengthened RC columns with large-eccentricity was distinguished by the yielding of tensile and compressive longitudinal steel bars, the rupturing of longitudinal CFRP sheet, and the crushing of compressive concrete. With the increase of predamaged degree or eccentricity, the maximum bearing capacity of specimens decreased. In contrast, CFRP strips spacing had little effect on bearing capacity. Considering the effect of predamaged degree and eccentricity, a modified model for conveniently predicting the stress-strain relationship of CFRP strengthened predamaged RC columns under eccentric compression was proposed. On the basis of experimental study, the influence coefficients of predamaged degree and eccentricity and a strain distribution coefficient of CFRP strips were introduced, a calculation formula for predicting bearing capacity of high predamaged rectangular RC columns strengthened with CFRP under eccentric compression was proposed and validated test data with good agreement.bearing capacity, concrete column, damaged degree, eccentric loading, failure mode, fiberreinforced polymer, reinforcement, stress-strain relationship Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.