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Abstract A hollow concrete column (HCC) is a structurally efficient construction system and uses less material. Conventionally, HCCs are reinforced with steel bars, which are prone to corrosion. This study explored the use of glass-fiber-reinforced-polymer (GFRP) composite bars as reinforcement for HCCs and evaluated the effect of the reinforcement ratio on HCC structural behavior. A total of six HCCs reinforced longitudinally with GFRP bars with different reinforcement ratios (1.78%, 1.86%, 2.67%, 2.79%, 3.72, and 4.00%) were prepared and their behavior was investigated. The different reinforcement ratios were achieved by changing the bar diameter (12.7 mm, 15.9 mm, and 19.1 mm) and number of bars (4, 6, 8, and 9 bars). The results show that increasing the diameter and number of bars enhanced the strength, ductility and confinement efficiency of HCC. For columns with equal reinforcement ratios, using more and smaller-diameter GFRP bars yielded 12% higher confinement efficiency than in the columns with fewer and larger-diameter bars. The crushing strain of the GFRP bars embedded the HCC was 52.1% of the ultimate tensile strain. Lastly, the axial-load capacity of the GFRP-reinforced HCC can be reliably predicted by considering the contribution of the concrete and up to 3000 μ ε in the longitudinal reinforcement. [ABSTRACT FROM AUTHOR]

Abstract Glass fiber-reinforced polymer (GFRP) panels have been increasingly used for structural applications due to their light weight, corrosion resistance and construction-easiness. This study evaluates the seismic performance of GFRP wall panels based on comprehensive shaking table tests and Finite Element Analysis (FEA). A GFRP wall panel is experimentally subjected to harmonic ground motions of frequencies ranging from 10 to 15 Hz. A mass is attached to the top of the panel to simulate gravitational weight. The panel remains undamaged under a peak base acceleration of 2.1 g. Its FEA is conducted using Abaqus based on Rayleigh damping. There is a good correlation between the experimental and FEA results. Another FEA model is developed to study the seismic behavior of a Reinforced Concrete (RC) wall, which is validated by results from an existing study. The two FEA models are then used to compare the seismic performance of GFRP wall panels versus RC walls in terms of drift ratio and hysteretic behavior. It is found that while GFRP wall panels cannot replace RC walls in multi-story buildings due to their low stiffness, their performances are comparable to RC walls for low-rise buildings. Therefore, GFRP wall panels can be potentially used in low-rise buildings in seismic regions. [ABSTRACT FROM AUTHOR]

The use of glass fiber reinforced polymer (GFRP) composite bars as internal reinforcement for concrete is rapidly increasing especially in structures exposed to aggressive environments. A proper bond mechanism between GFRP bar and concrete is essential to ensure proper functioning of such structures. The slippage between the concrete and reinforcement has usually been ignored in numerical modeling of reinforced concrete (RC) structures. In this study, the effect of the bond action in flexural behavior of GFRP RC slabs was investigated. The analysis was first performed by considering a perfect bond between the concrete and reinforcement and ignoring any slippage. Next, an experimentally obtained bond-slip relation was used to replace the unrealistic perfect bond assumption. The predicted flexural load-deflection response of the slab was compared to the experimental data. The result obtained by incorporating the bond-slip model showed a better agreement with the experimental data. Hence, considering the slippage between the GFRP and concrete may be necessary when accurate deflection estimate is required under the service condition. Additionally, it was shown that the perfect bond assumption was sufficiently safe for the design of the GFRP RC slabs. [ABSTRACT FROM AUTHOR]

Corrosion of steel rebars is known to cause deterioration of concrete structures that can lead to catastrophic failures. To mitigate this problem, steel rebars can be replaced with Glass Fiber-Reinforced Polymer (GFRP) rebars. However, the lack of ductility of GFRP-reinforced elements has prevented their use in many structural applications, especially in seismic areas. Stainless Steel (SS) rebars are corrosion resistant and have adequate energy absorption and ductility. However, they are much more expensive than steel rebars. This paper proposes the combined use of SS and GFRP rebars to achieve ductile and corrosion-free elements. The first challenge for such a proposal relates to designing SS-GFRP reinforced concrete frame with adequate lateral performance in terms of initial stiffness, ductility, and strength. Design equations, which are based on a comprehensive parametric study, are developed to allow designing such a frame. A six-storey concrete frame is then designed using the proposed equations and its lateral performance is examined using pushover analysis. [ABSTRACT FROM AUTHOR]

The possibility of replacing the traditional steel reinforcement with glass fiber reinforced polymer (GFRP) cages in precast concrete tunnel segmental lining has been shown by the authors in previous papers. The use of GFRP rebars as structural reinforcement in precast tunnel segments, allows several advantages in terms of structural durability or in cases of temporary lining that will have to be demolished later. Furthermore, this reinforcement type can be a suitable solution to create dielectric joints, ensuring the interruption of possible stray currents, which often lead to corrosion problems. Nevertheless, this peculiar application requires curvilinear shape of the reinforcement, and then different production process and rebar geometries. In the present work, a suggestion for the optimization of the GFRP reinforcement for tunnel segment is given. Four different GFRP cage typologies are analysed and applied as a reinforcement in full-scale tunnel segments. Both bending and point load tests are developed and the structural performances of the specimens are compared and discussed. Finally, the best solution, in terms of cost-benefit analysis is proposed. [ABSTRACT FROM AUTHOR]

The in-plane compression and shear performance plays a significant role in achieving an optimum and reliable design of pultruded glass fiber-reinforced polymer (GFRP) bridge deck supported on steel girders that have been used in bridge decks retrofit application or new construction in the past decade. This paper presents a summary of several laboratory experiments that were performed on a pultruded GFRP bridge deck for pedestrian or light vehicular loading in order to evaluate both the deck’s in-plane compression and shear properties. The experimental results showed that the average web thickness has a relatively larger influence on the in-plane shear behavior than the in-plane compressive behavior. Three-dimensional finite element models utilizing the Hashin’s theory laminate failure, adhesive layers failure via cohesive element and initial geometry imperfections by using limited critical eigenmodes multiplied by empirical coefficient were employed to numerically simulate both the deck’s in-plane compression and shear ultimate capacity and stiffness based on elastic engineering constants obtained from micromechanics. The numerical results agreed well with experimental results that could provide a reference for the design and construction of such type of pultruded composite bridge decks. [ABSTRACT FROM AUTHOR]

Damage recovery after low-velocity impact has been assessed in woven E-glass fibre-reinforced polymer composites with an epoxy matrix and a blend of epoxy and 25 vol% of poly(ε-caprolactone) (PCL). Impact was carried out at three energy levels (8.5, 17, 34 J) and composites with epoxy-PCL blends demonstrated similar energy absorption capacity as compared to pure epoxy composites even though the extent of damage (quantified by C-scans and optical microscopy) was higher. Ultimate compressive residual strength of the modified composites was, for the different impact energy levels, 23–33% lower as compared to unmodified composites. Healing efficiency after a thermal mending cycle at 150 °C for 30 min has been quantified using three complementary characterization methods; impact damage could be recovered from 20% to 100% depending on the impact energy level. These modified matrix composites are thus able to fully recover low-velocity impact damage at energy levels often met in real structures. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental investigation into the durability behaviour of textile-reinforced concrete (TRC) subjected to both tensile and bending loads to compare its macroscale characterization. Composites are produced as a laminate material using 2 and 6 layers of glass fibre mat as reinforcements. The instantaneous and long-term (durability) properties of composite TRC are identified by tensile and flexural testing with specimens made from the same fresh mortar. The long-term tests are conducted in two ageing environments: natural ageing, which was conducted under the laboratory atmosphere (20 °C and 50% RH), and accelerated ageing, which consisted of immersion of the specimens in hot water at 50 °C. The durability performance of TRC is evaluated by the reduced macroscale performance and damage mechanisms. The effects of the reinforcement ratio, testing conditions, and thermal conditions on the long-term response of TRC are investigated, and the microstructure of both matrix and fibre is observed and discussed after the tests with observations via scanning electron microscopy (SEM). The addition of layers of glass fibre (reinforcement ratio) increased the strength capacity and the first macro-crack strength of TRC in both tensile and bending tests. The ultimate strength value of the TRC composites obtained from the tensile test is lower than that from the bending test over the same tested days as a result of the different redistribution mechanisms; however, the difference between tensile and flexural stress remains approximately equal with similar deviations. An increase in the tensile and flexural strength capacity over the ageing time is observed before 90 days of ageing. However, after 90 days, the test results showed a loss of ductility of the accelerated aged specimens. [ABSTRACT FROM AUTHOR]

The fire resistance of two concrete slabs reinforced completely with glass fibre reinforced polymer (GFRP) bars was experimentally investigated through a full-scale standard fire test. The Canadian standard on design of FRP reinforced buildings (CSA S806) currently requires 60 mm of clear concrete cover in a FRP reinforced concrete slab to ensure 2 h of fire resistance. The two concrete slabs, which were identical in every aspect except the types of GFRP reinforcing bars, were designed and fabricated with 60 mm concrete cover in this experiment to examine the fire resistance of the existing FRP reinforced concrete structures designed using CSA S806. The uniformly distributed loads were applied causing flexural moment of 45 kN·m, which was 55% of the ultimate moment resistance of the slabs at room temperatures, and sustained throughout the fire test. Both loaded slabs endured more than three hours of ASTM-E119 standard fire exposure. The results promised a more efficient and economic application of FRP reinforcing bars in concrete construction. The effects of concrete cover, unexposed length in providing adequate anchoring at the ends, and two different types of widely used GFRP reinforcing bar were studied in this research. [ABSTRACT FROM AUTHOR]

• Precast high HPC sheet piles prestressed with GFRP bars prototypes are presented. • Three Full scale experimental tests on HPC sheet piles prestressed with GFRP bars are carried out; • The flexural behaviour is analysed, up to failure; • One more than three years aged specimen is tested for analysing the influence of the time on the global behaviour. • Effectiveness of simplified analytical sectional models. Since decades, the prestressed reinforced concrete technique, with steel strands, has been widely used in structural and infrastructural fields. The paper deals with the possibility to replace the traditional steel strands with new composite Glass Fiber Reinforced Polymer (GFRP) bars for the prestressing of precast High Performance Concrete (HPC) sheet piles. The use of prestressing combined with composite reinforcing bars could be a good solution in all those cases where the attention of the design is focus on durability, structural lightness, speed of execution, sustainability, economic savings due to the reduction of the structure maintenance. In order to evaluate the potentiality and feasibility of the proposed technique, full-scale experimental tests on sheet piles are carried out at the Laboratory of the University of Rome Tor Vergata. A suitable design and check procedure is also applied and discussed. [ABSTRACT FROM AUTHOR]

• Precast high HPC sheet piles prestressed with GFRP bars prototypes are presented. • Three Full scale experimental tests on HPC sheet piles prestressed with GFRP bars are carried out; • The flexural behaviour is analysed, up to failure; • One more than three years aged specimen is tested for analysing the influence of the time on the global behaviour. • Effectiveness of simplified analytical sectional models. Since decades, the prestressed reinforced concrete technique, with steel strands, has been widely used in structural and infrastructural fields. The paper deals with the possibility to replace the traditional steel strands with new composite Glass Fiber Reinforced Polymer (GFRP) bars for the prestressing of precast High Performance Concrete (HPC) sheet piles. The use of prestressing combined with composite reinforcing bars could be a good solution in all those cases where the attention of the design is focus on durability, structural lightness, speed of execution, sustainability, economic savings due to the reduction of the structure maintenance. In order to evaluate the potentiality and feasibility of the proposed technique, full-scale experimental tests on sheet piles are carried out at the Laboratory of the University of Rome Tor Vergata. A suitable design and check procedure is also applied and discussed. [ABSTRACT FROM AUTHOR]

In this investigation, full-scale reinforced-concrete (RC) circular-beams with glass fibre reinforcement polymer (GFRP) bars and spirals were modeled using nonlinear finite element (FE) program. All the specimens had 3000-mm length. The RC-beams were modeled in a three-dimension space, taking into account the material nonlinearity and the elastic plastic behavior of the concrete, in addition to the elastic characteristics of the GFRP materials. The results of the numerical analysis were verified by comparing them against experimental results of six similar previously tested specimens, that had 500-mm diameter. The analysis included tracing the load-deformation response of the RC circular-beams, load-strains behavior on the surface of the concrete as well as the strains in the GFRP bars. The outputs from the FE analysis showed that the program was able to foresee the experimental results with good precision. The, average, value for the experimental shear strength to the foreseen ones by the FE program, (V exp /V Model) for the six beams, is "1.00 ± 0.05″ with 2.5% COV. After ward, a parametric study was performed to expand and evaluate more parameters such as size effect (200, 300, and 400 mm), span-to-depth (a/d) ratio from 1.5 to 3.5, and spirals' reinforcement ratio between 0.32 and 1.27%. The numerical investigation confirmed the prominent effect of these parameters on the shear strength and behavior of the GFRP-RC circular-beams. [ABSTRACT FROM AUTHOR]

The geopolymer concrete internally reinforced with fibre-reinforced polymer (FRP) bars is anticipated to offer durable, sustainable, and cost-effective civil infrastructures. In this study, the effect of the anchor head on the pullout behaviour of the sand coated glass-fibre-reinforced polymer (GFRP) bars embedded in the geopolymer concrete was investigated using a direct pullout test. Straight and headed GFRP bars with different nominal diameters ∅ (12.7, 15.9, and 19.0 mm) and embedment lengths l d (0 ∅ + l ah , 5 ∅ + l ah , and 10 ∅ + l ah for headed bars, where l ah stands for the anchor head length, and 5 ∅ and 10 ∅ for straight bars) were considered. The results showed that the provision of anchor head is an efficient method to enhance the anchorage capacity of GFRP bars in geopolymer concrete. The anchor heads improved the anchorage of the sand coated GFRP bars by as much as 49–77%. Furthermore, the mechanical bearing resistance provided by the anchor head alone resulted in the development of approximately 45% of the GFRP bars’ nominal tensile strength. A comparison of the experimental results with the published studies showed that a much higher load is required to pullout the GFRP bars in geopolymer concrete than in Ordinary Portland Cement-based concrete. [ABSTRACT FROM AUTHOR]

This paper reveals the influence of arching action on the shear behaviour of glass fibre reinforced polymer (GFRP) reinforced laterally restrained concrete slabs in bridge decks. A total of seventeen full-size one-way concrete slabs were constructed and tested in this study. Those restrained test slabs represents typical full-scale dimensions of a real bridge deck slab 400 mm wide by 2400 mm long and 200 mm deep. The test variables were lateral restraint stiffness, reinforcement configuration and concrete strength. The behaviour of test slabs was discussed and the influence of those structural parameters on the amount of arching action was evaluated by comparing the results of different specimens. The test results showed that increasing the arching effect resulted in shear failure mode and larger shear strength. The experimental shear strengths of the restrained test slabs were compared with some theoretical predictions in the literatures. The results indicated that those theoretical methods yielded high conservative predictions. A theoretical model that takes into account the effect of arching action in the shear-strength prediction was proposed by the writers. This method provided accurate and slightly conservative predictions. [ABSTRACT FROM AUTHOR]

A three-year research project ( Pontalumis ) was carried out for the development of an innovative simply supported hybrid footbridge, with 11 m of length and 2 m of width. The footbridge is composed of two pultruded I-shaped glass fibre reinforced polymer (GFRP) girders (400 × 200 (×15) mm 2 ) bonded and bolted to a 37.5 mm thick deck in steel fibre reinforced self-compacting concrete (SFRSCC). The present paper describes the material/structural concept of this footbridge, its design and construction process, and summarises the response of the prototype when submitted to static short and long-term load tests, and dynamic load tests. The prototype was simple and fast to execute, presenting a reduced dead-weight of only about 3 tonf. The static and dynamic behaviour of the prototype as well as its long-term deflection fulfil standards’ requirements for footbridge structures and are in good agreement with conventional analytical and numerical design tools. [ABSTRACT FROM AUTHOR]

Concrete-filled fiber reinforced polymer (FRP) tube (CFFT) members have become increasing popular, while the study on CFFT beams especially hollow CFFT beams is rather limited. This paper presents an experimental study on the flexural behaviour of hollow concrete-filled rectangular glass fiber reinforced polymer (GFRP) tubes beams. A total of six beams was fabricated and tested by using four-point bending. The parameters investigated in this study included the size of the hollow cores (0%, 5.7%, 12%, 27%) and the shape of the hollow cores (circle and rectangle). The experimental results show that the hollow CFFT beams exhibit an almost linear load–displacement behaviour and a brittle failure mode. The flexural stiffness of the hollow CFFT beams is slightly affected by the size and shape of the hollow cores. In addition, the proposed theoretical model verifies that the hollow core in the tension region also has a small effect on flexural strength of the hollow CFFT beams, and the flexural behavior is highly depended on the material properties of the GFRP tubes. In comparison with the conventional steel reinforced concrete beams, the hollow CFFTs beams have a lighter dead weight and a higher load-carry capacity. [ABSTRACT FROM AUTHOR]

Abstract: Due to the mechanical properties of fibre reinforced polymer (FRP) bars, deflections often drive the design of FRP reinforced concrete (RC) flexural members. This has led to an increasing number of studies focused on the analysis of short-term deflections of FRP RC beams. However, investigations and experimental data focused on long-term deflections are scarce. The time-dependent deflection in RC beams is a function of member geometry, material properties and loading characteristics. Maximum service loads, as well as repeated loading, affect the deflections under sustained loads. This paper presents the results and discussion of an experimental programme concerning eight glass FRP RC beams tested at service load, and subsequently subjected to sustained loading for 250days. Two reinforcement ratios and two levels of sustained load were considered. The experimental results revealed an effect of the loading–unloading processes and the reinforcement ratio on short and time-dependent deflections. No significant influence of the sustained load level was observed. Moreover, the theoretical predictions obtained with different models have been compared with the experimental results. The modified time-dependent factor presented in ACI 440.1R-06, together with the modified Bischoff’s equation to compute the immediate deflections due to sustained load, give the best agreement with experimental deflections. [Copyright &y& Elsevier]

Abstract: The seismic performance of a concrete filled fiber reinforced polymer (FRP) tube (CFFT) bridge column was studied through shake table testing and nonlinear dynamic analyses of a one-fifth scale two-column bridge pier that also incorporated a conventional RC column. The FRP tube in the CFFT column was a prefabricated composite pipe with glass fibers aligned in ±55° with respect to the tube axis to provide both hoop and longitudinal strengths. The columns had nearly the same flexural capacities. The accumulated dissipated hysteresis energy of the CFFT column normalized by steel ratio was 1.6 times larger than that of the RC column; yet, it remained visibly damage free up to a drift ratio of 7%. The CFFT column failed due to FRP tube rupture under 8.4% drift ratio. The equivalent plastic hinge length of CFFT column was found to be more than twice that of the RC column, which implies larger spread of plasticity and smaller local ductility demands. The nonlinear dynamic modeling of the pier response using OpenSees led to very good agreement with the measured response of the pier under moderate and large-amplitude motions. [Copyright &y& Elsevier]

Abstract: Due to their different mechanical properties, cracking and deformability behaviour of FRP reinforced concrete (FRP RC) members is quite different from traditional steel reinforced concrete (SRC) having great incidence on their serviceability design. This paper presents and discusses the results of an experimental programme concerning concrete tension members reinforced with glass fibre reinforced polymer (GFRP) bars. The main aim of the study is to evaluate the response of GFRP reinforced concrete (GFRP RC) tension members in terms of cracking and deformations. The results show the dependence of load-deformation response and crack spacing on the reinforcement ratio. The experimental results are compared to prediction models from codes and guidelines (ACI and Eurocode 2) and the suitability of the different approaches for predicting the behaviour of tensile members is analysed and discussed. [Copyright &y& Elsevier]

• Nine GRAGC columns were manufactured. • 3D FEM of all specimens was performed. • All GRAGC specimens failed in the middle portion. • FEM and theoretical predictions were close to the experiments. The increased quantity of construction and demolition waste and the high carbon footprint of cement production is creating significant environmental problems. This study explored the use of recycled coarse aggregates (RCA) in geopolymer concrete (GPC) and reinforced with glass fiber reinforced polymer (GFRP) bars and spirals to fabricate novel and structural GRAGC columns. A total of 9 GRAGC columns with 1150 mm in height and 250 mm in diameter were tested to failure under axial compression. The influence of a different number of longitudinal GFRP bars and spiral spacing on the cracking behaviour, ductility, and axial load-carrying capacity (LCC) were investigated. A nonlinear finite element model (FEM) was implemented to predict the axial compressive response of GRAGC columns. The experimental results depicted that an improvement in the ductility and lateral confinement was observed by decreasing the spacing of GFRP spirals. GRAGC columns with eight longitudinal GFRP bars portrayed the highest LCC. All tested GRAGC columns portrayed similar failure modes with the damage at the central region of the specimens. The theoretical model suggested over a database of 225 GFRP reinforced columns showed a high accuracy compared with the previous models. The present study suggests an efficient and environmental-friendly compression member. [ABSTRACT FROM AUTHOR]

Deterioration of concrete structures caused by corrosion of steel reinforcement is a significant problem worldwide with high remediation costs. This problem has been addressed by corrosion protection systems, which prevent chlorides from penetrating the concrete cover and reacting with steel reinforcement. However, these solutions are complex and require high maintenance costs. In this paper, we propose to add viscous dampers to GFRP RC frames to improve its energy absorption capacity under seismic loading. Three RC frames were designed; two GFRP frames, and one steel RC frame. The fundamental dynamic parameters of RC frames with and without viscous dampers were calculated and compared. Results show that GFRP and steel RC frames can reach a similar lateral deformation, but the former is more fragile, with failure occurring at the compression zone of beams. Our results show that the addition of viscous dampers reduces the lateral deformation and story drifts in the GFRP RC frames. Moreover, the energy dissipation of viscous dampers is more efficient at GFRP RC frames. We conclude that the ductility and energy dissipation capacity of GFRP RC frames can be improved by adding viscous dampers and high lateral confinement, which demonstrates better performance than steel RC frames. [ABSTRACT FROM AUTHOR]

Aim of the paper is the evaluation of the bond transfer mechanism and the following cracking behavior for concrete elements reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. At the scope, an experimental survey has been developed on nine 3000 mm long tie-specimens with square cross-section of 150 mm × 150 mm, reinforced with a 4000 mm long GFRP reinforcing bar embedded in the centerline. Besides the reference element, reinforced with conventional steel rebar with diameter equal to 16 mm, nine GFRP bars with the same equivalent diameter and different surface treatments (smooth, sand-coated and helical fiber wrapped surfaces) were taken into account. The specimens were subjected to tensile force and the obtained results have shown how the different surface coating may affect the bond behavior at the concrete – GFRP interface, and the following crack pattern. [ABSTRACT FROM AUTHOR]

This paper deals with strengthening statically indeterminate reinforced concrete (RC) beams with carbon and glass Fiber Reinforced Polymers (FRP) rods by using the Near Surface Mounted (NSM) technique. The test program consisted of six two-span beams; one control beam, which had exploited for comparison purposes, and five others initially strengthened in flexure with NSM-FRP rods in both hogging and sagging regions. The main test parameters were type, ratio and length of the FRP bars as well as characteristics of the filling material. The study presents and discusses their impacts on the global flexural behavior of continuous RC beam that mainly includes investigating the overall capacity, failure mode, moment redistribution and ductility state. All NSM-FRP strengthened beams displayed higher overall capacity than the control beam; the test results showed that implementing the NSM technique in an appropriate way could significantly improve the yielding capacity and load-carrying capacity of RC beams without large decrease in the ductility index or the moment redistribution degree despite the non-conventional failure mode. The beam failure was primary affected by the strengthening length; terminating the FRP bars before the zero moment point caused to change the failure mode from pull out of the FRP bars to premature peeling off of the concrete cover. On the other hand, moment redistribution and ductility of the NSM-FRP beams were negatively affected by: (I) Increasing the FRP reinforcement, (II) Decreasing the FRP length or (III) Using mortar as a filling material instead of epoxy-resin. Adopting a nonlinear analysis of the cross-sections could accurately quantify the moment–curvature and the ultimate load of the NSM-FRP continuous beams. [ABSTRACT FROM AUTHOR]

Combining seawater, recycled coarse aggregate (RCA), and glass fiber reinforced polymer (GFRP) reinforcement in concrete is potentially advantageous from a sustainability perspective. This paper reports on the results of an experimental study on the short-term flexural performance of seawater-mixed recycled-aggregate concrete beams with GFRP bars. Twelve medium-scale reinforced concrete (RC) beams (150 × 260 × 2200 mm) were tested under four-point loading. The test variables included the mixing water (seawater/freshwater), aggregate type (conventional/recycled), and reinforcement material (black steel/GFRP). A wide range of flexural properties, including failure mode, cracking behavior, load-carrying capacity, deformation, energy absorption, and ductility were characterized and compared among the beam specimens. The results suggest that the use of seawater and RCA in concrete has insignificant effects on the flexural capacity of RC beams, especially if concrete strength is preserved by adjusting the mixture design. Altering reinforcement material had a strong influence on the flexural capacity and performance of the tested specimens: the GFRP-RC beams exhibited higher load-carrying capacities (on average 25%) but inferior deformational characteristics as compared to their steel-reinforced counterparts. Theoretical predictions were obtained for the flexural capacity, crack width, and deflection of steel- and GFRP-RC beams based on their corresponding design guides, and compared with the experimental results. [ABSTRACT FROM AUTHOR]

Arranging a hybrid combination of longitudinal fiber reinforced polymer (FRP) bars and longitudinal steel bars in the tensile zone of a concrete beam is able to sufficiently exploit the superior properties of both FRP and steel materials to achieve a satisfactory ductility level. As the foundation of analysis and design of hybrid FRP-steel reinforced concrete (RC) members, study of tensile behavior of concrete chords with FRP-steel reinforcement is essential and necessary. In this paper, the average crack spacing of hybrid (Glass Fiber Reinforced Polymer-GFRP and steel) RC chords is analytically estimated. Subsequently, the Tension Chord Model (TCM) is extended to predict the tensile behavior of hybrid GFRP-steel RC chords. Finally, the presented models are effectively validated by experimental results of concrete chords reinforced with GFRP bars and steel bars in different combinations available in the literature, and detailed discussions about analytical and experimental results are also performed. [ABSTRACT FROM AUTHOR]

In this paper, six concrete beams reinforced with a combination of GFRP (glass fiber reinforced polymer) bars and steel bars, and three concrete beams reinforced only with steel bars were designed and tested. Several flexural behaviors of the tested beams were analyzed and compared with theoretical models. The experimental and analytical results showed that under the designed service loads, the crack width and deflection that appeared in the GFRP-steel reinforced concrete beams developed faster than those shown by the steel-reinforced concrete beams. With the same total reinforcement amount of GFRP and steel bars, the ultimate flexural capacity of GFRP-steel reinforced concrete beams was nearly 91–97% of that of steel-reinforced concrete beams, but the deflection and maximum crack width were obviously larger than those of steel-reinforced concrete beams under the same service load levels. The beam deformability coefficient approximately decreased with increasing nominal reinforcement ratio ρ nom,F. The area ratio of GFRP bars to steel bars A f / A s had a great influence on the flexural behaviors of GFRP-steel reinforced concrete beams. Comparisons showed that the data obtained for flexural capacity, deflection, deformability and crack width of GFRP-steel reinforced concrete beams were consistent with the predictions calculated by the proposed models. [ABSTRACT FROM AUTHOR]

The glass fiber reinforced polymer (GRFP) bars have advantages in corrosion resistance and high load bearing capacity. They can be used as reinforcements in concrete protective structures to replace the steel bars. In this paper, the GRFP bar reinforced concrete beams (GRCBs) were designed, casted and tested. As a reference, the steel bar reinforced concrete beams (SRCBs) having the same flexural rigidity with the GRCBs were also designed, casted and tested. Under close-in explosions, the GRCBs have smaller displacement than the SRCBs, because the GFRP bars are still in elastic state while the steel bars enter into plastic deformation. Cracks, spalling and cratering are the main damage modes of the concrete beams. Through the quasi-static four-point-bending experiments, the residual load capacity of each beam has been evaluated, which quantitatively reveals the damage degree of the exploded concrete beams. In current research the explosion produces negligible damage to the GRCBs, while the load capacity the SRCBs reduces at a level of 28% at the most. The research proves that the GRCB has greater blast-resistance. [ABSTRACT FROM AUTHOR]

This experimental work presents results on the effect of different concrete types on the flexural behavior and deflection of beams reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Four different types of concretes namely; ordinary Portland concrete (OPCC), fiber reinforced concrete (FRC), geopolymer concrete (GPC), and fiber reinforced geopolymer concrete (FRGC) were used. A total of eight beams were subjected to four-point static bending tests. The parameters studied were load capacities, deflection, and strain development in concrete and rebars, while cracking patterns and failure modes were also observed. All tested beams exhibit comparable flexural and deflection characteristics. The results indicate that GPC and FRGC beams were more effective for a GFRP reinforced system than ordinary concrete. The ACI 440-R1-06 equations gave conservative estimates for both the flexural capacity and the deflection of the members and therefore may be used irrespective of the concrete type. Finally, results from flexural capacities normalized for concrete strength, cross-section and reinforcement ratio of GFRP (ρ f / ρ b) indicate that increase in the ρ f / ρ b ratio does not proportionally increase the flexural strength of the beams. [ABSTRACT FROM AUTHOR]