• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.669-675
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• 1997

This paper investigates the performances of GFRP bar and its possibility for using a substitute of steel bar. GFRO bar was made with introducing the glass fiber into GTR added UPE. We carried out the tensile test of GFRP and steel bar and out the three point bend test bond-test and fracture energy measurement on the GFRP bar and steel bar reinforced concrete. The GFRP bar was excellent as comparison with steel bar in the contribution to the energy absorption and the ductility of concrete. But its tensile, bond and bend strengthes were comparatively small. In order to improve these defects, we judged that glass fibers in GFRP bar must be completely adhesive one another by the impregnating glass fibers into UPE.

• Structural Engineering and Mechanics
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• v.63 no.5
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• pp.629-637
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• 2017

Continuous concrete beams are commonly used as structural members in the reinforced concrete constructions. The use of fiber reinforced polymer (FRP) bars provide attractive solutions for these structures particularly for gaining corrosion resistance. This paper presents experimental results of eight two-span continuous concrete beams; two of them reinforced with pure glass fiber reinforced polymer (GFRP) bars and six of them reinforced with combinations of GFRP and steel bars. The continuous beams were tested under monotonically applied loading condition. The experimental load-deflection behavior and failure mode of the continuous beams were examined. In addition, the continuous beams were analyzed with a numerical method to predict the load-deflection curves and to compare them with the experimental results. Results show that there is a good agreement between the experimental and the theoretical load-deflection curves of continuous beams reinforced with pure GFRP bars and combinations of GFRP and steel bars.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1221-1236
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• 2015

Since the coefficients of thermal expansion (CTE) between concrete and GFRP, steel and GFRP are quite different, GFRP laminates with different laminas stacking-sequence present different thermal behavior and currently there is no specification on mechanical properties of GFRP laminates, it is necessary to investigate the thermal influence on composite girder with stay-in-place (SIP) bridge deck at different levels and on different scales. This paper experimentally and theoretically investigated the CTE of GFRP at lamina's and laminate's level on micro-mechanics scales. The theoretical CTE values of laminas and laminates agreed well with test results, indicating that designers could obtain thermal properties of GFRP laminates with different lamina stacking-sequence through micro-mechanics methods. On the basis of the CTE tests and theoretical analysis, the thermal behaviors of composite girder with hybrid GFRP-concrete deck were studied numerically and theoretically on macro-mechanics scales. The theoretical results of concrete and steel components of composite girder agreed well with FE results, but the theoretical results of GFRP profiles were slightly larger than FE and tended to be conservative at a safety level.

• Computers and Concrete
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• v.31 no.6
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• pp.513-525
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• 2023

This research presents the experimental and theoretical evaluations on circular steel-fiber-reinforced-concrete (SFRC) columns reinforced by glass-fiber-reinforced-polymer (GFRP) rebar under the axial compressive loading. Test programs were designed to investigate and compare the effect of different parameters on the structural behavior of columns by performing tests. Theses variables included conventional concrete (CC), fiber concrete (FC), steel/GFRP longitudinal rebars, and transversal rebars configurations. A total of 16 specimens were constructed and categorized into four groups in terms of different rebar-concrete configurations, including GFRP-rebar-reinforced-CC columns (GRCC), GFRP-rebar-reinforced-FC columns (GRFC), steel-rebar-reinforced-CC columns (SRCC) and steel-rebar- reinforced-FC columns (SRFC). Experimental observations displayed that failure modes and cracking patterns of four groups of columns were similar, especially in pre-peak branches of load-deflection curves. Although the average ultimate axial load of columns with longitudinal GFRP rebars was obtained by 17.9% less than the average ultimate axial load of columns with longitudinal steel rebars, the average axial ductility index (DI) of them was gained by 10.2% higher than their counterpart columns. Adding steel fibers (SFs) into concrete led to the increases of 7.7% and 6.7% of the axial peak load and the DI of columns than their counterpart columns with CC. The volumetric ratio had greater efficiency on peak loads and DIs of columns than the type of transversal reinforcement. A simple analytical equation was proposed to predict the axial compressive capacity of columns by considering the axial involvement of longitudinal GFRP rebars, volumetric ratio, and steel spiral/hoop rebar. There was a good correlation between test results and predictions of the proposed equation.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.399-415
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• 2023

This paper presents the experimental and numerical evaluations on the circular SFRC columns reinforced GFRP rebars under the axial compressive loading. The test programs were designed to inquire and compare the effects of different parameters on the columns' structural behavior by performing experiments and finite element modeling. The research variables were conventional concrete (CC), fiber concrete (FC), types of longitudinal steel/GFRP rebars, and different configurations of lateral rebars. A total of 16 specimens were manufactured and categorized into four groups based on different rebar-concrete arrangements including GRCC, GRFC, SRCC, and SRFC. Adding steel fibers (SFs) into the concrete, it was essential to modify the concrete damage plastic (CDP) model for FC columns presented in the finite element method (FEM) using ABAQUS 6.14 software. Failure modes of the columns were similar and results of peak loads and corresponding deflections of compression columns showed a suitable agreement in tests and numerical analysis. The behavior of GFRP-RC and steel-RC columns was relatively linear in the pre-peak branch, up to 80-85% of their ultimate axial compressive loads. The axial compressive loads of GRCC and GRFC columns were averagely 80.5% and 83.6% of axial compressive loads of SRCC and SRFC columns. Also, DIs of GRCC and GRFC columns were 7.4% and 12.9% higher than those of SRCC and SRFC columns. Partially, using SFs compensated up to 3.1%, the reduction of the compressive strength of the GFRP-RC columns as compared with the steel-RC columns. The effective parameters on increasing the DIs of columns were higher volumetric ratios (up to 12%), using SFs into concrete (up to 6.6%), and spiral (up to 5.5%). The results depicted that GFRP-RC columns had higher DIs and lower peak loads compared with steel-RC columns.

• Steel and Composite Structures
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• v.34 no.1
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• pp.17-34
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• 2020

This paper investigates the flexural behavior of concrete beams reinforced longitudinally with either steel bars, molded glass-fiber reinforced polymer (GFRP) grating mesh or pultruded glass-fiber reinforced polymer (GFRP) grating mesh, under four-point bending. The variables included in this study were the type of concrete (normal weight concrete, perlite concrete and vermiculite concrete), type of the longitudinal reinforcement (steel bars, molded and pultruded GFRP grating mesh) and the longitudinal reinforcement ratio (between 0.007 and 0.035). The influences of these variables on the load-midspan deflection curves, bending stiffness, energy absorption and failure modes were investigated. A total of fifteen beams with a cross-sectional dimension of 160 mm × 210 mm and an overall length of 2400 mm were cast and divided into three groups. The first group was constructed with normal weight concrete and served as a reference concrete. The second and third groups were constructed with perlite concrete and vermiculite concrete, respectively. An innovative type of stirrup was used as shear reinforcement for all beams. The results showed that the ultimate load of the beams reinforced with pultruded GFRP grating mesh ranged between 19% and 38% higher than the ultimate load of the beams reinforced with steel bars. The bending stiffness of all beams was influenced by the longitudinal reinforcement ratio rather than the type of concrete. Failure occurred within the pure bending region which means that the innovative stirrups showed a significant resistance to shear failure. Good agreement between the experimental and the analytical ultimate load was obtained.

• Steel and Composite Structures
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• v.45 no.5
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• pp.653-663
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• 2022

This study reports the results of a series of tests of pultruded glass fiber reinforced polymer (P-GFRP) box section composite profile columns, geometrically similar with/without concrete core, containing 0-1-2-3% steel fiber, with different lengths. The recycled steel wires were obtained from waste tyres. The effects of steel fiber ratio on the collapse and size effect of concrete filled P-GFRP columns under axial pressure were investigated experimentally and analytically. A total of 36 columns were tested under compression. The presence of pultruded profile and steel wire ratio were selected as the primary variable. The capacity of pultruded profiles with infilled concrete are averagely 9.3 times higher than the capacity of concrete without pultruded profile. The capacity of pultruded profiles with infilled concrete are averagely 34% higher than that of the pultruded profiles without infilled concrete. The effects of steel wire ratio are more pronounced in slender columns which exhibit buckling behavior. Moreover, the proposed analytical approach to calculate the capacity of P-GFRP columns successfully predicted the experimental findings in terms of both pure axial and buckling capacity.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.237-240
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• 2006

The corrosion of steel reinforcing bar has been the major cause of the reinforced concrete deterioration. GFRP(Glass Fiber-Reinforced Polymer) reinforcing bar has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. However, GFRP rebar is prone to deteriorate due to other degradation mechanisms than those for steel. The high alkalinity of concrete, for instance, is a possible degradation source. This paper presents the long-term deterioration of the GFRP rebar under alkali environmental condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.518-521
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• 2006

The purpose of this study is to evaluate structural performance of concrete beam reinforced simultaneously with GFRP and steel rebar. Because the GFRP has lower elastic modulus than steel or CFRP, serviceability for concrete structure can be an issue. According to the test result, the hybrid reinforced specimen showed better stiffness improvement than the specimen reinforced with only GFRP rebar. From an additional research on design parameter and reliability analysis, the field adaptability can be proved.

• Structural Engineering and Mechanics
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• v.66 no.5
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• pp.631-636
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• 2018

This study aims to investigate the flexural behaviour of glass fibre reinforced polymer (GFRP) laminated hybrid fibre reinforced concrete (HFRC) beams. The flexural and ductility performance of GFRP laminated HFRC beams having different proportions of polyolefin and steel fibres with 1.0% of total volume fraction were investigated. The parameters of this investigation included: load and deflection at first crack, yield, and ultimate stages, ductility and crack width. A total of seven beams of $150{\times}250mm$ in cross-section were tested in the laboratory over an effective span of 2800 mm. One reinforced concrete (RC) beam without any internal or external GFRP was taken as the reference beam. Of the remaining six beams, one beam was strengthened with GFRP, one beam with 100% steel fibres was strengthened with GFRP and four beams, each with different volume proportions of polyolefin and steel fibres (20:80, 30:70, 40:60, 50:50) were strengthened with GFRP. All the above beams were tested until failure. The experimental results show that a fibre volume proportion of 40:60 (polyolefin-steel) has significantly improved the overall performance of the tested beams.