Glass Fiber Reinforced Polymer Reinforcement Research Articles

Numerical study on the seismic response of GFRP and steel reinforced masonry shear walls with boundary elements

Reinforced masonry (RM) shear walls with boundary elements (BE) have been recently presented as a ductile alternative to RM rectangular shear walls. The present study addresses the applicability of reinforcing masonry shear walls with glass fibre-reinforced polymer (GFRP) bars to attain reasonable strength and drift. GFRP-RM shear walls are a corrosion-free lateral resisting system that is transparent to magnetic fields and radio frequencies and nonconductive thermally and electrically. A numerical macro-model is developed using OpenSees to simulate the in-plane response of flexure-dominated reinforced masonry shear walls with boundary elements (RMSW-BE). The model was validated against experimentally tested walls from the literature. The boundary elements were designed with C-shaped masonry blocks. A numerical study is performed on thirty-four flexure-dominated shear walls to evaluate the influence of different design parameters on the inelastic behaviour of RMSW-BEs under quasi-static fully reversed cyclic loading. The investigated parameters are transverse hoop spacing, amount of vertical reinforcement in the boundary element, GFRP or steel reinforcement, and aspect ratio of the wall. In addition, walls with rectangular boundary elements were investigated to study the effect of increasing their size on the overall wall response. The influence of the design parameters on the hysteretic response, stiffness degradation, effective stiffness, and ductility related response modification factor was investigated to evaluate the enhancement in the seismic performance of RM buildings with RMSW-BE.

Behaviour of FRC segments with GFRP cage under TBM thrust in presence of GAPs

Due to their structural performance and durability, Fibre Reinforced Concrete (FRC) precast segments are now commonly used in major tunnelling applications around the world. The paper investigates the effects of irregular loading on the segments due to poor alignment, which can occur on the tunnel lining during construction as a result of the operation of the Tunnel Boring Machine (TBM). During construction, as the TBM progresses, defects on the tunnel lining can arise. Cracks can then be caused by improper load application by the TBM thrust jacks (due to uncorrected inclination or eccentricities). Further defects can be caused by non-uniform ring joints and this needs to be taken into account in the design and construction of the lining. Because the precast segments are not supported uniformly by the previous ring, they are subjected to a transient bending moment that can jeopardise their integrity and performance during both the excavation phase and service life. The proposed hybrid solution of FRC segments with Glass Fibre Reinforced Polymer (GFRP) reinforcement presented in this paper can overcome these situations, which cannot be satisfied with FRC-only segments, by means of an “elastic-return action” provided by the GFRP reinforcement. Two full-scale tests simulating the TBM thrust, for which irregular support conditions were taken into account, were carried out. Based on the obtained results, it is concluded that the proposed hybrid solution shows almost full recovery of the initial geometry with residual crack widths measuring 79% less compared to the FRC-only solution.

Efficiency of GFRP bars and hoops in recycled aggregate concrete columns: Experimental and numerical study

To develop a sustainable environment and to alleviate the problems of the large annual production of construction and demolition waste, the recycled aggregate concrete (RAC) has been used in the columns reinforced with glass fiber reinforced polymer (GFRP) bars. This study explores and compares the structural behavior of GFRP reinforced recycled aggregate concrete columns (GRAC columns) and steel bars reinforced recycled aggregate concrete columns (SRAC columns) under concentric and eccentric loadings. 18 circular concrete columns having a diameter of 250 mm and a height of 1150 mm were manufactured from which 9 samples consisted of GFRP reinforcement and the other 9 samples consisted of steel bars. The test measurements portrayed that the GRAC columns showed lower axial strength (up to 7.79%) with higher ductility indices (up to 4%) compared with SRAC columns. Both GRAC and SRAC columns showed similar failure modes and cracking patterns. Furthermore, both GRAC and SRAC columns presented significant reductions in the axial strength due to the loading eccentricities. The present study proposed a three-dimensional nonlinear finite element model (FEM) for predicting the structural response of GRAC and SRAC columns using ABAQUS 6.14. The simulation of RAC was carried out using a modified concrete damaged plasticity (CDP) model and that of GFRP bars was carried out using a linear elastic model. A theoretical model for predicting the axial strength of GRAC columns was given based on a large database of 270 GFRP reinforced concrete columns. The close agreements were observed among the experimental results, numerical simulations, and theoretical predictions for GRAC columns.

Numerical simulation of double-sided concrete corbels internally-reinforced with GFRP bars

Three-dimensional (3D) finite element (FE) models were developed in this study to simulate the nonlinear structural behavior of double-sided concrete corbels internally-reinforced with glass-fiber reinforced polymer (GFRP) bars. The accuracy of the numerical models was demonstrated by comparing their results with published experimental data of twelve specimens tested previously by the authors. Two sets of models were first developed. In one set, a perfect bond assumption was adopted between the GFRP bars and the concrete. In the other set, a bond stress-slip law was adopted at the GFRP-concrete interface. Numerical results were in good agreement with those recorded experimentally, except for the specimens with a high concrete strength and high GFRP reinforcement ratio, which failed prematurely in a diagonal splitting mode of failure. In an effort to capture such a mode of failure numerically, additional four models were developed without considering the tension-softening curve in the concrete material constitutive law. Results of the models with the bond-slip law were insignificantly lower than those with perfect bond assumption at GFRP-concrete interface. Eliminating the tension-softening curve from the concrete material constitutive law used in modeling specimens with a high concrete strength and high GFRP reinforcement ratio yielded numerical results closer to those obtained from the tests.

Flexural performance of concrete beams reinforced by gfrp bars and strengthened by cfrp sheets

Glass-fiber-reinforced polymer (GFRP) bars reinforced concrete beams and fortified by carbon-reinforced polymer (CFRP) slips can provide high resilience, high sustainability and reasonable strength for a building scheme. Few experiments contract the combined operation of these products and this was the undertaking's fundamental impetus. The presented study includes an extensive and interesting experimental analysis of the flexural efficiency of reinforced concrete beams GFRP bars and fortified by CFRP sheets. A total of ten GFRP reinforced concrete beams are equipped, experienced and subject to frequent loading series using a four-point bending expedient to complete a catastrophe analysis. The main parameters were GFRP reinforcement ratio and number of CFRP sheets. The central deflection, crack size and concrete strains of the verified beams were verified and contrasted. In this study, the feasibility of using particle image velocimetry (PIV) to detect cracks established in reinforced concrete beams were discovered so that a practical effect can be suggested. The PIV technique has been realistic for analyzing the surface field movement and strain. The test results discovered that the crack sizes and central deflection were considerably decreased by increasing the reinforcement ratio and number of CFRP layers, results characterized that due to its lower cost and strong capacity to observe cracking efficiency, PIV method can be used as a substitute for traditional measuring methods during specific structural tests, exclusively in bending tests.

Effect of GFRP Reinforcement Ratio on the Strength and Effective Stiffness of High-Strength Concrete Columns: Experimental and Analytical Study

Abstract This paper reports the axial–flexural test results for 12 high-strength concrete (HSC) columns reinforced with glass fiber-reinforced polymer (GFRP) rebars to evaluate the implication of u...

Strength of Bridge High-Strength Concrete Slender Compression Members Reinforced with GFRP Bars and Spirals: Experiments and Second-Order Analysis

Design for slender high-strength concrete (HSC) bridge compression members (columns, piers, and piles) reinforced with glass fiber-reinforced polymer (GFRP) has yet to be addressed in the relevant American and Canadian codes and guidelines. Including such provisions undoubtedly requires a comprehensive assessment of the structural performance of such members, as well as a definition for the slenderness limit below which second-order responses can be discarded. Consequently, full-scale slender GFRP-HSC columns with a concrete compressive strength of 80 MPa and measuring 2,500 mm in height and 305 mm in diameter were prepared and tested at four eccentricity levels (0%, 16%, 33%, and 66% of the column size). The influence of HSC on the behavior of slender GFRP-HSC columns was also assessed with respect to reference normal-strength concrete (NSC) counterparts. Moreover, the effect of two different longitudinal GFRP-reinforcement ratios (3.28% and 4.66%) on the performance of the test specimens was investigated. The test results herein indicate the ability of HSC and GFRP reinforcement to improve column strength and to maintain stability at various loading stages. An analytical second-order model was then developed to extend the research program to include a wide range of parametric studies. The developed model was validated against the test results for 47 FRP-HSC columns selected from the current study and the literature. Lastly, the applicability of the current slenderness limit to HSC columns was verified and a modified slenderness limit was proposed to account for HSC columns with compressive strengths up to 125 MPa.

Effects of Internal Force Redistribution on the Limit States of Continuous Beams with GFRP Reinforcement

Fiber-reinforced polymers (FRP) are commonly used as internal reinforcement in RC structures in aggressive environments. The design of concrete elements reinforced with FRP bars is usually ruled by serviceability criteria rather than the ultimate limit state. Six continuous concrete beams over two spans with longitudinal and transverse glass FRP (GFRP) reinforcement were investigated until failure to estimate the effects of different reinforcement arrangements on the limit states of continuous beams. The ratio of longitudinal reinforcement between the midspan and middle support sections (i.e., the design moment redistribution) and the type of GFRP reinforcement were the main parameters. The experimental results were compared to prediction models and other code formulations under serviceability and ultimate limit states. The bond-dependent coefficient kb was investigated to assess adhesion conditions for GFRP reinforcement and concrete. The results showed that moment redistribution in continuous beams with GFRP reinforcement happens with slippage between the reinforcement and concrete in the middle support without the load capacity being reduced. A modified model was suggested for better deflection prediction of continuous beams reinforced with GFRP bars. Based on deformability factors, the tested continuous beams, although containing GFRP reinforcement that has brittle behavior, showed a certain kind of ductile behavior.

Behavior of axially loaded low strength concrete columns reinforced with GFRP bars and spirals

This paper investigates the behavior of circular concrete columns reinforced with glass fiber reinforced polymer (GFRP) bars and spirals under axial load. Nine circular low strength concrete columns of 230 mm diameter and 1500 mm height were constructed and tested. The test parameters included reinforcement type (GFRP and steel), longitudinal reinforcement ratio, and spacing of spirals. Most tested columns showed two peak loads. Test results revealed that the GFRP-RC columns behaved similarly to the steel-RC counterparts. However, the GFRP-RC columns gave a slightly lower first peak load compared to their counterparts reinforced with steel. Increasing the GFRP reinforcement ratio slightly enhanced the capacity of the columns. Highly confined columns showed better ductile failure and significantly increased the second peak load of the columns. Design equations that predict the capacity of FRP-RC columns were evaluated using the experimental data of this study. The results showed that the Canadian Standard Association equation was conservative especially for columns with high reinforcement ratios. In addition, three different confinement models were used to predict the maximum confined concrete strength and they gave reasonable predictions compared to the experimental ones. Furthermore, an existing analytical model was used to predict the load-axial displacement of the tested columns and it showed reasonable correlation with the experimental ones up to the first peak loads. However, significant deviations were observed at the post-peak stages.

Durability of Commercially Available GFRP Reinforcement in Seawater-Mixed Concrete under Accelerated Aging Conditions

Abstract The effect of seawater used as mixing water in concrete on the long-term properties of glass fiber–reinforced polymer (GFRP) bars is the focus of this work. The durability of GFRP bars emb...

Internal GFRP Reinforcement of Low-Grade Maritime Pine Duo Timber Beams.

This paper presented an experimental structural-scale test campaign used to analyze the flexural behavior of low-grade maritime pine (Pinus pinaster Ait.) duo timber beams reinforced with an internal glass fiber-reinforced polymer (GFRP) sheet. For this purpose, thirty (30) unreinforced duo beams and thirty (30) duo beams internally reinforced with a unidirectional GFRP sheet with an areal mass of 1200 g/m2 were produced and tested. The addition of a low GFRP reinforcement ratio (1.07%) in the tension zone of the duo beams provided an average improvement of 8.37% in bending stiffness (EI) and an increase of up to 18.45% in ultimate moment capacity. In addition to this improved bending behavior, the internal GFRP reinforcements seemed to decrease the influence of wood singularities and wood heterogeneity on mechanical properties, which allowed for better characteristic values to be reached and for the achievement of results with less variability.

Flexural behavior investigation of steel-GFRP hybrid-reinforced concrete beams based on experimental and numerical methods

Due to their superior corrosion resistance and strength-to-weight ratio, GFRP (glass fiber reinforced polymer) rebar are widely used as reinforcement for concrete structures, but the brittleness of GFRP and their inferior bonding performance with concrete needs to be addressed. Hybrid reinforcement is a strategy to address the brittleness of GFRP rebar, but the inferior bonding performance may cause inaccuracy in the performance prediction. To determine the effects of bonding performance on the flexural behavior of GFRP- and hybrid-reinforced concrete beams and compare their flexural behaviors, both types of beams were prepared and subjected to four-point bending tests in this research. Their flexural capacities from the experimental results were then compared with the theoretical results. Additionally, the bond-slip relation between the GFRP rebars and concrete was obtained by means of pull-out tests, and an FE model based of the bond-slip results was developed to simulate the flexural behavior of the beams. From the experimental results, the hybrid reinforcement was shown to be able to control the beginning of cracking and reduce the maximum crack width by over 50% in concrete compared that of to GFRP reinforcement at the same load level. The flexural behavior of the hybrid-reinforced beam can be accurately predicted by the theoretical and FE methods. For the GFRP-reinforced beams, the theoretical method overestimates the flexural capacity by 9%; according to the results from the FE simulation, inclusion of the nonlinear bond-slip constitutive relation between the GFRP rebar and concrete helps to mitigate the underestimation of the mid-span deflection from 14.4% to 2.1%.

Assessment Study of Glass Fiber-Reinforced Polymer Reinforcement Used in Two Concrete Bridges after more than 15 Years of Service

Assessment Study of Glass Fiber-Reinforced Polymer Reinforcement Used in Two Concrete Bridges after more than 15 Years of Service

Deformability and Stiffness Characteristics of Concrete Shear Walls Reinforced with Glass Fiber-Reinforced Polymer Reinforcing Bars

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Effect of flexural reinforcement type and ratio on the punching behavior of RC slab-column edge connections subjected to reversed-cyclic lateral loads

Three full-scale reinforced-concrete (RC) slab-column edge connections were constructed and tested to failure under a combination of gravity load and uniaxial reversed-cyclic lateral load. The main test parameters were the flexural reinforcement type [steel or glass fiber-reinforced polymer (GFRP)] and flexural reinforcement ratio [0.7 or 1.4%]. The performance of the connections was evaluated in terms of mode of failure, hysteretic response, stiffness, energy dissipation and strains in the reinforcement. It was demonstrated that GFRP-RC connections are able to safely achieve or exceed the minimum 1.50% drift capacity before punching failure with adequate deformability. The low modulus of elasticity and high tensile strength of GFRP bars allowed GFRP-RC connections to experience comparable reinforcement strains to those in the steel-RC counterpart. In addition, the linear nature of GFRP reinforcement resulted in lower stiffness degradation and lower residual damage in GFRP-RC connections compared to the steel-RC connection.

Glass fibre-reinforced polymer circular alkali-activated fly ash/slag concrete members under combined loading

Glass fibre reinforced polymer (GFRP) reinforced alkali-activated fly ash/slag concrete (AAFS) could potentially be used as a durable construction material, especially in aggressive environments. This study aims to examine the structural behaviour of circular GFRP-reinforced AAFS members under combined loading, and introduces a geometrical factor for predicting the load and moment interaction of circular members. A total of 17 reinforced AAFS columns and beams (14 with longitudinal GFRP bars and 3 with steel bars) was constructed. GFRP spirals were used in all the specimens as transverse reinforcement. The effect of the number of longitudinal bars, the spiral pitch, the material of longitudinal bars and load eccentricities on confinement, load and moment capacity and failure modes was investigated. The GFRP reinforcement resulted in slightly reduced load capacities of 10%, however with an average improved ductility of 24% compared to steel reinforcement. The confinement was found to be affected by a combination of longitudinal and transverse reinforcement. The differences in load capacities between columns with 40 mm and 80 mm spiral pitches gradually diminished as the eccentricity increased. Interaction diagrams were constructed and validated based on the experimental data. The introduced geometrical factor could be used safely and effectively to obtain the equivalent stress block of circular sections. The calculation with a smaller stress block factor was the most accurate to the experimental results of AAFS members due to their reduced stress block size.

Effectiveness of Glass Fiber-Reinforced Polymer Stirrups as Shear Reinforcement in Glass Fiber-Reinforced Polymer Reinforced Concrete Edge Slab-Column Connections

Effectiveness of Glass Fiber-Reinforced Polymer Stirrups as Shear Reinforcement in Glass Fiber-Reinforced Polymer Reinforced Concrete Edge Slab-Column Connections

Finite element modelling of shear critical glass fibre-reinforced polymer (GFRP) reinforced concrete beams

ABSTRACT Due to the different properties of GFRP bars, the available finite element packages for modelling shear critical GFRP reinforced members are questionable. This paper presents a three-dimensional (3D) nonlinear finite element analysis (FEA) model for shear critical glass fibre-reinforced polymer (GFRP) reinforced concrete beams. The beams were reinforced in longitudinal direction and there was no shear reinforcement. The FEA were carried out using concrete damage plasticity model in ABAQUS along with suitable constitutive model for concrete. Perfect bond was assumed between concrete and GFRP reinforcement. A generalized bi-linear tension stiffening model, based on the strain energy density, was used to model the contact between the concrete and GFRP bars. The FEA results were compared with the test results of GFRP reinforced beams. The robustness of the model was investigated for three different parameters: depth of beam, shear span to depth ratio, and concrete strength. The results obtained from FE analysis were analyzed for its load-deflection behaviour, crack patterns, ultimate loads; and the FE results were also compared with the test results. The comparison reveals that the model predicts the behaviour of shear critical GFRP reinforced concrete beams with reasonable degree of accuracy. Abbreviation: Glass Fibre Reinforced Polymer (GFRP)

Experiment on RC Beams Reinforced with Glass Fibre Reinforced Polymer Reinforcements

This study presents the flexural behaviour of rectangular concrete beams reinforced with surface treated Glass Fibre Reinforced Polymer (GFRP), Grooved bars and Sand sprinkled reinforcing bars. Beams cast with standard mix of M30 grade concrete, with a reinforcement ratios of 0.73%, and compared with that of conventional steel reinforced beams. Totally five rectangular beams of size 125 mm x 250 mm x 3200 mm were cast. The flexural study was carried under static two point loading. The experimental prediction was focused on observation of ultimate load capacity, cracks propagation and crack widths and failure modes of beams. The results indicate that both type of GFRP reinforcements are at par with the conventional steel reinforcements.

Splice Strength of Staggered and Non-Staggered Bundled Glass Fiber-Reinforced Polymer Reinforcing Bars in Concrete

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