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Glass Fiber-Reinforced Polymer (GFRP) bars can enhance the flexural bearing capacity and durability of concrete beam members under sustained loading and alkaline environment over an extended period. However, addressing the challenges related to durability and deformation resistance remains crucial for long-term service. In this paper, the flexural performance of GFRP-reinforced concrete beams with different glass fiber contents under the coupling action of the alkaline environment and continuous load is studied, and the mechanism of improving the flexural performance of GFRP-reinforced concrete beams by dispersed fibers is analyzed from a microscopic point of view by scanning electron microscope (SEM) test. In addition, the finite element analysis software was used to simulate and verify the improvement effect of singly dispersed fiber on the bending of GFRP-reinforced concrete beams. The results demonstrate that GFRP-RC beams containing 0.5%, 1.0%, or 1.5% glass fiber exhibit a reduction in deflection ranging from 11% to 23% compared GFRP-RC beams without glass fiber, thereby improving their deformation resistance. The optimal glass fiber content is 1.5%. Simulation analysis demonstrates that the model exhibits enhanced resistance to deformation when the glass fibers are randomly dispersed. Specifically, increasing the random scattering of fibers at the bottom of the beam by two to three times results in a reduction of 7%-12% in mid-span displacement of the model. Additionally, within the cracked area, the fibers bear greater tensile stress compared to those in other uncracked regions, effectively preventing further cracking of GFRP-RC beams. This study offers valuable design guidance for enhancing performance of GFRP-RC members during long-term service. • This paper studied glass fiber GFRP-RC beams. • The working condition is the coupling of sustained loading and alkaline environment. • The influence of fiber on the flexural property of beam was investigated by finite element method. • The corrosion age of alkaline environment is 450 d. [ABSTRACT FROM AUTHOR]

This study addresses the mechanical limitations of concrete fabricated with recycled brick and concrete as partial replacement of coarse aggregates, which exhibit inferior strength and stiffness compared to those with natural aggregates. To rectify this, a cost-effective approach involving low-cost glass fiber-reinforced polymer composites (LOC-GFRP) is proposed. The key parameters considered were the plain concrete compressive strength and the quantity of LOC-GFRP layers. The compressive strength of LOC-GFRP-confined concrete increased with the number of layers, with greater improvements observed in lower-strength plain concrete. Moreover, the improvement in ultimate strain was more significant than the improvement in compressive strength. The compressive strength and ultimate strain were improved by 271% and 478%, respectively. LOC-GFRP confinement resulted in a bilinear compressive stress vs. strain response, showcasing increased ductility and strength with more LOC-GFRP layers. The study evaluated various existing analytical expressions for fiber-reinforced polymers but found them inadequate in predicting parameters accurately. As a result, nonlinear regression analysis was carried out to propose expressions for predicting compressive strength and ultimate strain of LOC-GFRP-confined concrete for different aggregate types. The calculated coefficient of determination values ≥ 0.90 confirmed the good correlation among experimental and predicted values. ● Low-cost glass fiber-reinforced polymer composites (LOC-GFRP) were proposed. ● LOC-GFRP confinement resulted in bilinear compressive stress-strain responses. ● Strength and strains of LOC-GFRP-confined concrete specimens were predicted. [ABSTRACT FROM AUTHOR]

Highlights • Tensile behaviour of different GFRP laminates under elevate temperatures has is investigated. • Laminates with continuous unidirectional fibers showed the best tensile performance. • Laminates with chopped strand fibers showed the weakest tensile performance. • Laminates with continuous woven fibers performed better than chopped strand and weaker than unidirectional laminates. Abstract This study was aimed at gaining an improved understanding of the behavior of glass fiber-reinforced polymer laminates at elevated temperatures by means of testing laminate specimens with unidirectional, woven, and randomly distributed (chopped strand mat) fibers. The testing parameters were temperature, the type of fiber, and the thickness of the laminates. The failure modes of the specimens and their elasticity moduli at ambient temperature were investigated, and analysis of variance was conducted to determine the contribution of each parameter to the behavioral test results. The findings showed that among the parameters, an increase in temperature exerted the strongest effect on the specimens. The unidirectional laminate specimens exhibited the best performance, maintaining nearly 40% of their loading capacity at 550 °C. At this temperature, the woven laminate specimens could not carry any tensile load, and at 400 °C, the laminate specimens containing randomly distributed fibers lost all their strength. [ABSTRACT FROM AUTHOR]

Highlights • Bond of GFRP bars in high strength concrete was investigated using hinged beams. • Bond performance was studied with showing the effect of main parameters on bond. • Design code predictions were compared to the experimental results. Abstract Although several research studies have been conducted on investigating the bond stress – slip behaviour of Glass-Fibre Reinforced Polymer (GFRP) bars embedded in high strength concrete (HSC) using a pull-out method, there is no published work on the bond behaviour of GFRP bars embedded in high strength concrete using a hinged beam. This paper presents the experimental work consisted of testing 28 hinged beams prepared according to RILEM specifications. The investigation of bond performance of GFRP bars in HSC was carried out by analysing the effect of the following parameters: bar diameter (9.5, 12.7 and 15.9 mm), embedment length (5 and 10 times bar diameter), surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) and bar location (top and bottom). Four hinged beams reinforced with 16 mm steel bar were also tested for comparison purposes. The majority of beam specimens failed by pull-out. Visual inspection of the test specimens showed that the bond failure of GFRP (HW-SC) bars usually occurred owing to the bar surface damage, while the bond failure of GFRP (SC) bars was caused due to the detachment of sand coating. The GFRP bars with helical wrapping and sand coated surface configurations showed different bond behaviour and it was found that the bond performance of the sand coated surface was better than that of the helically wrapped surface. Bond strength reduced as the embedment length and bar diameter increased. It was also observed that the bond strength for the bottom bars was higher than that of the top bars. The bond strength was compared against the prediction methods given in ACI-440.1R, CSA-S806 and CSA-S6 codes. All design guidelines underestimated the bond strength of both GFRP re-bars embedded in high strength concrete. [ABSTRACT FROM AUTHOR]

Highlights • The behavior of spliced GFRP and steel bars in normal concrete (NC) and self-consolidated concrete (SCC) are presented. • Failure modes of spliced GFRP and steel bars in NC and SCC are presented and discussed. • The effect of splice length and section height along with the type of concrete on the bond capacity were discussed. • The accuracy of the current design provisions is assessed based on the test results. Abstract The bond behavior of reinforcing bars is one of the critical issues in the design of reinforced-concrete (RC) structures. This paper sheds light on the effect of various parameters on the bond behavior of spliced glass-fiber-reinforced-polymer (GFRP) bars in self-consolidating concrete (SCC) and normal concrete (NC). A total of 11 full-scale RC beams measuring 4300 mm in length, 250 mm in width, and 400 or 600 mm in height were constructed and tested under four-point bending up to failure. The test parameters included (1) concrete type; (2) splice length (20 db and 40 db, where db is the bar diameter); (3) beam height (400 or 600 mm); and (4) longitudinal-reinforcement type (GFRP or steel). The test results are reported and discussed. In addition, the splice-length predictions using JSCE-97, CSA S806-12, CSA S6-14, and ACI 440.1R-15 were assessed. Furthermore, a recommendation was made to improve the design equation suggested in CSA S6-14. The test results show that the SCC beams exhibited load capacity, crack pattern, failure mode, and load-deflection response similar to their NC counterparts. The bond strength of the reinforcing bars in the SCC beams was similar or slightly lower than that of the NC beams. Moreover, the JSCE-97 provisions gave the highest safety margin. [ABSTRACT FROM AUTHOR]

Highlights • Tensile test results on conditioned GFRP bars were collected from the literature. • Bars were subjected to contemporary sustained stress and aggressive environment. • The sustained stress had a limited influence on the bar residual tensile strength. • Characteristic and design reduction factors for long-term behavior were calibrated. Abstract Glass fiber reinforced polymer (GFRP) bars can be employed as an alternative to steel bars for internal reinforcement of concrete elements. Although GFRP bars have been used to reinforce concrete for the last two decades, their long-term behavior is still an open issue. The tensile strength of bars subjected to aggressive exposure conditions has been investigated by different authors. However, clear and reliable indications on the bar residual strength are still lacking. Furthermore, the effect of sustained stress on the bar tensile strength is not completely clear and severe limitations on the stress level attained by the bar are imposed by available design guidelines. In this paper, the effect of sustained stress on GFRP bars exposed to different environmental conditions, namely air, alkaline environments, deionized water, and salt solutions, is studied by analyzing a database comprising 127 GFRP bar tensile tests collected from the literature. The results are analyzed and discussed to investigate the effect of sustained stress on the tensile strength of GFRP bars and to calibrate characteristic and design values for tensile strength long-term reduction factors. [ABSTRACT FROM AUTHOR]

Highlights • Recycled glass fiber reinforced polymer (GFRP) was used as reinforcement in the mortar. • Fiber-like GFRP shapes replaced fine aggregate in mortar. • Aspect ratios were compared in terms of toughness and strength. • Volumetric percentages of 1 and 3 showed the most successful results. Abstract Glass fiber reinforced polymer (GFRP) panels from retired wind turbines were recycled into discrete structural elements in mortar. Based on 7-day testing, out of Powder, Small, Medium, and Large fiber size groups, the Large group was identified as the optimum size due to the highest modulus of rupture (MR) and toughness index (TI) while maintaining comparable compressive strength (f’ c) relative to control. Implementing the Large group at 1, 3, and 5% replacement of sand resulted in 5, 25 and 35% increases in 90-day MR with significant increases in TI and minimal reductions in f’ c and no expansion due to alkali-silica reaction. [ABSTRACT FROM AUTHOR]

Concrete-filled fiber-reinforced polymer tube (CFFT) columns have demonstrated superior advantages on mechanical behavior and ease of construction during the past few decades. The fiber-reinforced polymer (FRP) tube not only improves the mechanical properties of the concrete core by confinement, but also provides a protection layer for the concrete against the outer corrosive environment. However, one obstacle hindering the greater acceptance of the FRP composite as a conventional construction material in civil engineering applications is the susceptibility of FRP to complex, severe environmental exposure. The purpose of this study is to investigate the durability of CFFT cylinders with glass fiber reinforced polymer (GFRP) tubes under exposure to combined freeze/thaw, heating/cooling, and wet/dry cycles. The effects of combined sustained load and environmental conditions were also investigated during this study. Compression and hoop tensile tests were carried out on both conditioned and controlled specimens. In addition, scanning electron microscopy (SEM) and differential-scanning calorimetry (DSC) tests were used to characterize the aging effect on physical and thermal properties of FRP material. Test results showed that more pronounced degradation occurred on the ultimate strain than on the ultimate strength. The sustained load had a negative effect on CFFT cylinders by creating more microcracks in the GFRP tube. [ABSTRACT FROM AUTHOR]

Effective shear transfer at the interface of glass fibre reinforced polymer (GFRP) and concrete sections is crucial to achieve structural integrity of the composite panel. This study proposed a shear connector consisting of circular hollow sections (CHS) to enhance shear transfer between concrete and GFRP. Push-out and three-point bending tests were conducted to evaluate the static response of the proposed connectors compared to the adhesive bonding. The results showed that GFRP-concrete composite section using proposed shear connectors achieved partial composite action and non-linear behavior could be observed before the GFRP section failed in shear along the fibre direction at the contact zone. The mechanical properties of the connectors can affect the bearing capacity and stiffness of the composite structure. Numerical simulation using finite element (FE) method was able to capture the overall mechanical response with respect to loading force and deformation. Using a validated FE modelling technique, a comprehensive parametric study was carried out. Results showed that flange thickness, fibre orientation and shear connector arrangement can significantly affect the flexural capacity of GFRP-concrete composite. [ABSTRACT FROM AUTHOR]

Fiber reinforced polymer (FRP) rebars have recently been gaining popularity in the construction industry all around the world while steel rebars have been widely used so far. FRP bars, which have higher tensile strength compared to steel rebars with the same nominal diameter under normal conditions, are composed of resin matrix and fibers. In this study, mechanical and bonding properties of glass fiber reinforced polymer (GFRP) and steel rebars subjected to elevated temperature effects were investigated throughout a correlative comparison. Axial tensile tests and pull-out tests of these materials were performed subsequent to exposing them into elevated temperature effects in the range of 23–800 °C. Severe effects on the tensile properties of bare steel bars were observed after 600 °C, while this critical limit is 300 °C for bare GFRP bars. Test results show that bond strength degradation is almost linear for both type of rebars, however, 600 °C is also the critical temperature regarding the serious deterioration on concrete. Additionally, an empirical modeling approach on the bond strength degradation of rebars at elevated temperatures was proposed and it was found that comparison results have quite promising consistency based on the modeling process. [ABSTRACT FROM AUTHOR]

In order to alleviate the problem of growing construction waste and utilize the favorable material properties of fibre-reinforced polymer (FRP), a novel form of composites, FRP-recycled aggregate concrete-steel columns (FRSCs), was proposed based on hybrid FRP-concrete-steel double-skin tubular columns (DSTCs). The composite of FRSC consists an outer FRP tube and an inner steel tube with an annular area of recycled aggregate concrete (RAC) filled between both tubes. To further investigate the compressive behavior of these composites, an experiment of Glass FRP-RAC-steel tubular long columns (FRSLCs) was performed subjected to monotonic axial compression. Three parameters were designed in the test, which are the recycled coarse aggregate (RCA) replacement ratio, the slenderness ratio and the cross-section loading method. The influence of these parameters was analyzed on the bearing capacity, lateral deflection performance and the load-strain relationship of FRSLCs. The test results show that FRSLCs have good bearing capacity and excellent ductility. Two models for DSTCs were transformed to apply in FRSLCs, which has found that Lu’s model (2013) is appropriate to predict the ultimate bearing capacity of FRSLCs under the whole area loading. [ABSTRACT FROM AUTHOR]

Using seawater and recycled concrete aggregate (RCA) in a concrete mix is potentially advantageous from a sustainability perspective. However, the high chloride levels expected in such a case demands the use of non-corrosive reinforcement in lieu of normal black steel to avoid corrosion problems. Glass fiber reinforced polymer (GFRP) is considered promising as an alternative reinforcement owing to its corrosion resistance and acceptable mechanical properties that minimize maintenance and repairs and extend service life. However, the relatively high initial cost of GFRP bars may mitigate its potential use. To account for these factors, a life cycle cost analysis (LCCA) has been conducted to establish the relative cost savings of structural concrete combining seawater, RCA, and GFRP reinforcement in high-rise buildings compared with a traditional concrete mix and other reinforcement materials, such as black steel and stainless steel. The proposed combination of seawater, RCA, and GFRP in structural concrete was found to achieve cost savings over a 20-year period following initial construction. The life cycle cost (LCC) obtained for the proposed combination was approximately 50% less than that of the conventional counterpart (i.e. concrete with freshwater, natural aggregates, and black steel) based on a 100-year study period. The use of stainless-steel reinforcement to enhance durability was also found to be potentially advantageous but less cost-effective than using GFRP. The LCC of stainless-steel reinforced concrete was estimated to be 15% lower than that of the traditional steel-reinforced counterpart, with a payback period of 50 years. Results were found to be highly sensitive to the assumed discount rate and construction costs. The proposed combination achieved cost savings only with a real discount rate ( r ) of 5.9% or higher. Likewise, using stainless-steel reinforcement was found cost-effective at r ⩽ 1.35 % and nominal construction costs exceeding 85% of the material cost. The differences in concrete mixture cost, however, appeared to have insignificant influence on the ultimate LCCA results compared to those obtained from altering the reinforcement material. [ABSTRACT FROM AUTHOR]

The combined effect of sustained loading and moist seawater-contaminated concrete environment on the durability performance of two types of glass fiber-reinforced polymer (GFRP) bars was investigated. A sustained load of 25% of the ultimate tensile strength was applied to concrete-encased GFRP bars immersed in tap water for up to 15 months at temperatures of 20, 40, and 60 °C. None of the loaded specimens conditioned at 20 °C were creep-ruptured during conditioning. In contrast, many bars were creep-ruptured during conditioning at the higher temperatures of 40 and 60 °C. At a conditioning temperature of 20 °C, Type I and II GFRP bars retained 84 and 70% of their original tensile strength after 15 months of conditioning under a sustained load. At the higher temperature of 60 °C, trivial tensile strength retentions of 15 and 12% were recorded for Type I and Type II GFRP bars, respectively, after 15 months of conditioning under a sustained load. A comparative analysis between results of loaded and unloaded specimens demonstrated the detrimental effect of the presence of a sustained load during conditioning on the tensile strength retention of GFRP bars. The detrimental effect of the sustained load was intensified at the higher temperatures. The accelerated aging test data along with Arrhenius concept were employed to develop a durability design model that can predict the tensile strength retention of both types of GFRP bars in moist seawater-contaminated concrete. [ABSTRACT FROM AUTHOR]

• Eight full-scale GFRP reinforced concrete beams were tested in flexure to study bond of lap splices. • Studied parameters included contact and non-contact laps and spacing of confining stirrups. • Gap between lapped bars & reduction in confining stirrups' spacing enhanced bond strength of bars. • Authors' previous models for predicting development length and bond are found to show good predictions. • Analytical models are developed to predict the peak load of GFRP reinforced beams having lap splices. Fiber-reinforced polymer (FRP) bars are becoming a popular replacement for steel rebars that are vulnerable to corrosion, especially under harsh corrosive environments. Despite several advantages for using FRP rebars, the bond between FRP bars and surrounding concrete has been a major concern that affects the behavior of FRP-reinforced structural members. The experimental program of this study comprises testing eight full-scale glass FRP (GFRP) reinforced beams under two-point loads. There were two control beams and six beams having rebar lap splices. The beams were reinforced using 2ϕ12 GFRP bars. The first control had continuous GFRP bars, and the 2nd control had GFRP lap splice conforming to the relevant ACI code. The lap splice was 65 times the bar diameter in six beams having lap splice. The contact lap and non-contact laps were used along with the variable spacing of shear stirrups in the lap zone (50, 100 mm, ∞, i.e., no shear stirrups). The lap splice, designed conforming to the ACI code, was found to be very conservative. The reduction in shear stirrups' spacing in the lap zone and the gap between lapped bars was found to enhance the bond performance of GFRP bars by up to 31 %. The authors' previous models for predicting development length and bond are found to show good predictions for the experimental results of the present study as well. Analytical models are developed for predicting with sufficient precision the peak load for GFRP reinforced beams with the two types of lap splices (non-contact and contact). [ABSTRACT FROM AUTHOR]

In the current paper the authors present a series of case studies which expose innovative use of FRPs in engineering and architecture. A particular focus is set on the development of novel fabrication processes specifically devised for the projects, namely the Coreless Winding and the Assembled Core methods. The Assembled Core method stems from ongoing research in the field of FRPs production technology. This approach primarily focuses on the optimisation of the core geometry, allowing to produce complex components from a single winding core, thus reducing material waste and enhancing the efficiency of the fabrication process. After production the segments are extracted from the original core geometry and reassembled into the whole component, later serving as mould for concreting and eventually as reinforcement for the structure. The fabrication process was applied to the construction of a concrete bench, displaying the potential and capacities of this method. The second manufacturing process presented as part of the current research, the Coreless Winding technique, offers an alternative to classical filament winding by replacing the positive mould with a linear steel frame, which provides the armature onto which the resin-soaked fibres are tensioned. C oreless Winding was successfully implemented in the production of a full-scale architectural prototype, an entirely carbon and glass fibre based monocoque shell. The second case study demonstrates the use of FRP based components for the production of a large scale structure. The Coreless Winding technique is adapted to the production of small size elements, which later serve as basic components for the assembly of a modular and double layer structure, allowing a larger span and the optimal transfer of global bending moments. The requirement of fabrication flexibility is resolved by adopting a specific robotic fabrication setup and an adaptive winding frame. Along with the planning of these alternative winding techniques, specific computational tools had to be developed to accurately simulate the fabrication processes and the mechanical response of the final structures. [ABSTRACT FROM AUTHOR]

In this paper, the durability of flax and glass fiber-reinforced polymer (FRP) composites externally bonded to concrete beams is studied. A total of 100 plain concrete beam specimens (75 mm × 100 mm × 400 mm) were prepared and bonded with flax and glass FRP strips to the tension side of the beams. The specimens were designed to have an adhesive debonding failure of the FRP from the concrete. The specimens were aged in water and dry heat conditions at 20 and 60 °C for 21, 42, and 63 days and then were tested under three-point bending. A set of specimens were also aged by freeze/thaw cycles. The load-deflection behaviors of the specimens were evaluated and the effects of heat, moisture, and freeze/thaw cycles on the peak load and ductility of the specimens were quantified. The study shows that the peak load retentions of the specimens with bonded flax and glass FRPs immersed in 60 °C water for 63 days is 72% and 80% of their counterparts kept in dry heat condition, respectively. An analysis of variance was also performed to assess the significance of the aging effects on the physical and mechanical properties of the specimens. Also, a cross-sectional analytical modeling was performed to compute the FRP tensile force, strain, and bond strength of the specimens. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and analytical study on the shear behavior of concrete beams reinforced with lab produced glass fiber reinforced polymers (GFRP) bars and stirrups. The bars and stirrups are manufactured by double parts die mold using local resources raw materials at lab. A total of ten beams measuring 120 mm wide, 300 mm deep and 1550 mm long were casted and tested up to failure under four-point load. The main parameters were concrete compressive strength and the vertical GFRP web reinforcement ratio in the form of the number of GFRP stirrups (without stirrups and with 8 @ 215, 8 @ 150 and 8 @ 100 stirrups). The mid-span deflection, inclined crack load and GFRP reinforcement bars and stirrups strains of the tested beams were recorded and compared. The test results revealed that the shear capacity increasing by 41% and 82% of the shear carrying capacity of beam without stirrups by using web GFRP reinforcement of 8 @ 215 and 8 @ 100 respectively. The shear capacity increased by 49% and 104% as the concrete compressive strength increased from 25 MPa to 45 MPa and 70 MPa respectively. The maximum value of measured strain in GFRP stirrups reached 0.0095. New approach to calculate FRP stirrups shear strength was proposed and verified throughout an assessment of experimental results of current study and previous works. The shear capacities of the tested specimens were calculated using the strut and tie models (STM) and non-linear finite element analysis (NLFEA). The average ratio of experimental shear capacity to calculated ( V exp / V pred ) using NLFEA and STM were 1.2 and 0.9 respectively. [ABSTRACT FROM AUTHOR]

This paper reports on the structural performance of concrete beams reinforced with hybrid reinforcement. Six concrete beams reinforced with a combination of steel and glass fiber-reinforced polymer (GFRP) bars and three other beams reinforced with only GFRP bars were tested in flexure. Over-reinforced hybrid beams showed higher strength and ductility than their GFRP-reinforced counterparts. The CSA-S806-12 equation accurately predicted the deflections of the hybrid-reinforced beams with high effective reinforcement ratios. Based on the test results, a bond coefficient was proposed to predict the crack width of the hybrid-reinforced beams using the ACI-440.1R-06 equation. A modified deformability factor was also utilized to assess the deformability of the hybrid-reinforced beams. Comparison between the experimental and predicted results showed the adequacy of the models used in predicting the load-carrying capacity, deflection, crack widths, and deformability of hybrid-reinforced concrete beams. [ABSTRACT FROM AUTHOR]

This paper presents an experimental, numerical and analytical study of the flexural behavior of concrete beams reinforced with locally produced glass fiber reinforced polymers (GFRP) bars. Glass fiber reinforced polymers (GFRP) reinforcement bars has a lower stiffness than steel reinforcement, which should be accounted for the ultimate and serviceability conditions, including the impact on member deflection and crack widths. The bars are locally produced by double parts die mold using local resources raw materials. A total of ten beams, measuring 120 mm wide × 300 mm deep × 2800 mm long, were cast and tested up to failure under four-point bending. The main parameters were reinforcement material type (GFRP and steel), concrete compressive strength and reinforcement ratio ( μ b , 1.7 μ b and 2.7 μ b ; where μ b is the reinforcement ratio at balanced condition). The mid-span deflection, crack width and GFRP reinforcement strains of the tested beams were recorded and compared. The test results revealed that the crack widths and mid-span deflection were significantly decreased by increasing the reinforcement ratio. The ultimate load increased by 47% and 97% as the reinforcement ratio increased from μ b to 2.7 μ b . Specimens reinforced by 2.7 μ b can produce some amount of ductility provided by the concrete. The recorded strain of GFRP reinforcement reached to 90% of the ultimate strains. A non-linear finite element analysis (NLFEA) was constructed to simulate the flexural behavior of tested beams, in terms of crack pattern and load deflection behavior. It can be considered a good agreement between the experimental and numerical results was achieved. Modifications to ACI 440.1R-06 equation for estimating the effective moment of inertia ( I e ) of FRP-reinforced concrete beams, using regression analysis of experimental results, is proposed by introducing empirical factors that effectively decrease the I e at high load level. The proposed equation is compared with different code provisions and previous models for predicting the deflection. It can proved that the proposed factors gives good estimation for the effective moment of inertia ( I e ) works well for FRP-reinforced concrete beams at high load level. [ABSTRACT FROM AUTHOR]

This paper presents the results of axial compression tests on recycled aggregate concrete (RAC) confined by glass fiber reinforced plastic (GFRP) tubes. The objective of this study is to evaluate the mechanical properties of GFRP-tube confined RAC under axial and eccentric compressive loading. The main parameters in the experiment are recycled coarse aggregate (RCA) replacement percentages (0%, 30%, 50%, 70% and 100%) and expansive agent contents (0%, 8% and 15%). Sixteen specimens were prepared, six specimens were tested under axial concentric compression load and ten specimens were tested under eccentric compression loading. Research findings indicate that both the RAC strength and deformation are obviously improved with the additions of expansive agent. It is also found that the peak stress of RAC confined by GFRP tubes decreases while the corresponding strain increases when the RCA replacement percentage is increased. [ABSTRACT FROM AUTHOR]

Highlights: [•] For first time, mechanical behavior of GFRP panels is computed directly as a function of their constituents. [•] A set of experiments is performed on constituents of the GFRP sandwich panels: skin and fiber insertion. [•] The resulting constitutive relationships are used in a nonlinear finite element model. [•] The models can predict the behavior of GFRP sandwich panels beyond their elastic limits. [•] A parametric study is performed to optimize the effects of skin and panel thickness, and fiber pattern. [Copyright &y& Elsevier]

Highlights: [•] The pull-out response of grouted FRP rods in steel tubes is analytically modeled. [•] The interfacial bond-slip model is incorporated into the analysis. [•] Different boundary conditions are considered in the analysis. [•] The solutions can be applied to the problem of FRP rods embedded in rock. [Copyright &y& Elsevier]

Highlights: [•] We suggested a section of a new module that would apply a large section. [•] We developed a new FRP composite girder that is filled with concrete. [•] It was confirmed the composite effect from confining concrete. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the findings of an experimental investigation into a novel FRP stay-in-place (SIP) structural formwork system for concrete slabs with particular emphasis on its ability to exhibit ductility. The system consists of a moulded Glass Fibre Reinforced Polymer (GFRP) grating bonded to square pultruded GFRP box sections as structural stay-in-place formwork for a concrete slab. Holes cut into the top flange of the box sections at a variable spacing allow concrete GFRP dowels to be inserted to act as shear studs. Experimental results indicate that the proposed shear connection provides robustness and ductility to the system, thus helping to solve the notorious ductility issue associated with construction using FRP materials. [Copyright &y& Elsevier]

Abstract: In recent years there have been an increasing number of applications of glass in civil engineering structural members, such as roofs, floors, beams and columns. Such interest stems basically from the aesthetical possibilities of glass, in particular its transparency. However, glass presents several limitations, including relatively low tensile strength and brittle behaviour, which contrasts with current design philosophies associated with more conventional materials, such as steel and reinforced concrete. One of the possibilities of overcoming these disadvantages is joining reinforcing materials to glass. The main goal of those transparent composite structural solutions is to increase the post-cracking residual strength and ductility of glass beams. This paper presents results of an experimental study about the flexural behaviour of multi-span composite beams made of annealed glass panes reinforced with GFRP pultruded laminates. The main goal of this study was to evaluate the post-cracking behaviour of such continuous beams, namely the influence of the adhesive used in their construction. The experimental programme included (i) material characterization tests, (ii) tensile tests on double lap joints between glass and GFRP pultruded laminates, bonded with different structural adhesives, and (iii) full-scale flexural tests on multi-span glass–GFRP composite beams, with interfaces bonded also with different adhesives. Results showed that multi-span glass–GFRP composite beams are able to exhibit significant post-cracking residual strength and ductility, stemming not only from their cross-sectional redundancy but also from their capacity to redistribute internal forces. The ultimate load and the post-cracking performance of the multi-span composite beams are significantly affected by the type of the adhesive used to bond GFRP to glass. [Copyright &y& Elsevier]

Abstract: Glass fibre reinforced polymer (GFRP) bars are being increasingly used to reinforce concrete members as an alternative to steel, particularly in harsh environments, owing to their main advantages that include high strength, low self-weight, electromagnetic transparency and non-corrodibility. However, besides being relatively expensive, GFRP bars have low elasticity modulus and exhibit linear elastic behaviour until failure, thereby providing no contribution to structural members’ ductility. This paper presents experimental and numerical investigations about the flexural behaviour of continuous concrete beams reinforced with GFRP bars, in particular on their capacity to redistribute internal forces. Small-scale flexural tests were carried out on 7 two-span beams with T cross-section: the main parameters analysed were the GFRP reinforcement ratio and the confinement level in critical zones of the beams, namely at the central support. The behaviour of the beams was analysed and compared in terms of serviceability and failure responses. The numerical investigations included the development of non-linear finite element (FE) models of all beams tested. After validation and calibration with the test data, a comprehensive parametric study was performed, in which the effects of (i) the span, (ii) the cross-section geometry, and (iii) the longitudinal GFRP reinforcement ratio on the moment redistribution capacity of full-scale continuous beams were evaluated. Results obtained show that moment redistribution occurs and that elastic analyses are considerably conservative. The confinement of the concrete at critical cross sections may be a good solution to enhance the plastic hinge ductility and consequently, the moment redistribution in GFRP reinforced concrete beams. [Copyright &y& Elsevier]

Abstract: Wood plastic composite (WPC) beams retrofitted with carbon and glass fiber-reinforced polymer (CFRP and GFRP) composites offer an attractive solution to enhance the behavior of wood in terms of strength and ductility, as well as altering the mode of rupture of such structural members. However, very little is known about their performance. Thus, this paper presents a theoretical model based on nonlinear WPC properties, to investigate the behavior of hybrid WPC–FRP beams. In order to calculate the bending moment, the model considers an exponential function in the stress–strain diagram of WPC in both tension and compression parallel to the fibers. A four-point bending test configuration was conducted as short-term experiments to determine the load–displacement relationships of WPC beams with CFRP and GFRP sheets adhered to the tensile side. In order to validate the employed approach, the results obtained from the theoretical model were compared with the experimental results where a satisfactory agreement was achieved. [ABSTRACT FROM AUTHOR]

Abstract: Recently a high modulus CFRP system was developed to enhance the load carrying capacity and serviceability of steel bridges and structures. However, the environmental durability of the system has not yet been demonstrated. This paper presents the findings of a research program that was conducted to evaluate the environmental durability of the bond of the proposed CFRP strengthening system to steel surfaces. The program consisted of testing 44 steel-CFRP double-lap shear specimens. The specimens were exposed to severe environmental conditions for different durations, up to 6months. Different methods to enhance the bond durability were studied including pre-treating the steel surface with a silane coupling agent, inserting a glass fiber layer within the adhesive and a combination of both methods of protection. The research findings indicate that the use of a silane coupling agent significantly enhanced the bond durability. While the presence of the glass fibers helped to enhance the initial bond strength of the system, it did not improve the durability of the bond. The use of both techniques enhanced both the overall bond strength and the environmental durability of the strengthening system. [Copyright &y& Elsevier]

Abstract: This paper presents the structural behavior of an innovative hybrid Fiber Reinforced Polymers (FRP) beam consisting of carbon/glass fibers and vinyl-ester resin. The advanced feature of this hybridization is the optimum use of carbon and glass fibers in the flanges to maximize structural performance while reducing the overall cost by using only glass fibers in the web section. A series of beam tests were conducted under four-point bending varying ratio of flange to web width (b f/b w) and volume content of carbon and glass fiber in the flanges. Experimental investigations revealed that the ratio of flange to web width of hybrid FRP I-shaped beams plays an important role in their structural behavior. Small flange beams (b f/b w =0.43) showed stable and linear behavior under bending moment and failed in a brittle manner by delamination of the compressive flange at the interfacial layers while wide flange beams (b f/b w =1.13) exhibited unstable and nonlinear behavior in the buckling and post-buckling region leading to delamination failure of the compressive flange. The experimental and analytical results discussed in this paper emphasize on the best composition of carbon and glass fibers for the optimum design of such hybrid beams. It is found that the maximum strength of hybrid FRP beams can be obtained with the volume content of carbon fiber to be 25–33%. Furthermore, the results of this study show the potential of applying hybrid FRP beams for bridge components. [Copyright &y& Elsevier]

Abstract: A radar nondestructive testing (NDT) technique using an airborne horn antenna operating in the far-field condition is developed for detecting damages such as debonding and concrete cracking in glass fiber reinforced polymer (GFRP)-wrapped concrete columns. The far-field airborne radar (FAR) NDT technique is advantageous for distant measurement in practical applications where contact/near-contact measurement becomes an issue. In this technique the radar antenna operates in inverse synthetic aperture radar (ISAR) mode. Laboratory measurements at the frequency range 8–18GHz are made on artificially damaged GFRP–concrete specimens for a preliminary validation of this technique. Collected frequency–angle measurements are further processed by the fast backprojection algorithm to render range–cross-range imagery for damage detection. From the reported measurements and imaging results the proposed FAR NDT technique is conceptually validated; the potential of this technique is shown in identifying defects and debonding in the GFRP–concrete interface regions of the concrete columns wrapped with these composite materials. [Copyright &y& Elsevier]

• The influence of cross-sectional, slenderness, elevated temperatures on the compression behavior of the GFRP pultruded profiles were studied. • It was observed that the capacity of GFRP pultruded profiles had been lost considerably as the temperature exceeded 120 °C. • It was concluded that the degradation trend of all the profiles capacity at elevated temperature was the same, a sudden drop near transition temperature, i.e., 90 °C, and a constant part at the temperature higher than 120 °C. • The specimens with the greater cross-sectional area to external perimeter showed higher compressive strength at elevated temperatures. • According to the results of ANOVA, the cross-section area to external perimeter ratio had the most impact on the performance of GFRP pultruded profiles at temperatures ranging from 25 to 90 °C and also from 120 to 400 °C. • The model form was proposed to predict the capacity degradation factor of GFRP pultruded profiles at elevated temperatures. The compressive performance of glass fiber reinforced polymer (GFRP) profiles subjected to elevated temperature was investigated through a large number of (3 0 0) tests. The effects of profile cross-sectional area, slenderness, and temperature on the behavior of the GFRP profiles at temperatures ranging from 25 to 400 °C were determined. It was observed that the compressive strength of the GFRP profiles has been decreased by half as the temperature exceeded 90 °C, i.e., close to the glass transition temperature of the matrix. The temperature and ratio of cross-sectional area to external perimeter were determined as two major parameters affecting section capacity. [ABSTRACT FROM AUTHOR]