Glass Fiber Reinforced Polymer Research Articles

Improving tensile properties of glass fiber-reinforced epoxy resin composites based on enhanced multiphase structure: The modification of resin systems and glass fibers

Glass fiber-reinforced polymer (GFRP) composites have been widely used as reinforced materials in marine engineering due to their good corrosion resistance and economic benefits. However, the mechanical properties of GFRP are lower than that of composites reinforced by carbon and aramid fibers etc. Methods to improve the mechanical properties of GFRP received ongoing attention. GFRP have various mechanical properties due to the characteristics of its multiple phases. This study developed an optimized processing method based on multiphase structures for GFRP composites, significantly enhancing the tensile properties of GFRP laminates. The modified GFRP can be produced efficiently by this method to meet more utilization situations in marine engineering. The influence of curing agents, silane coupling agents (SCA)-treated glass fibers (GFs), and nanomaterials on GFRP's tensile properties was investigated. The findings reveal a 10.64 % increase in the characteristic load of GF bundles due to the improved bonding between fibers by SCA. Besides, the contact angle between SCA-treated GFs and epoxy resin shows a significant reduction (26.69 %). Variations in ply thickness and resin system distinctly influence the tensile properties and failure modes of GFRP laminates. Laminates with 4-ply GF fabrics facilitate more effective load transfer across the matrix-fiber boundary, yielding optimal tensile properties for GFRP. Epoxy/phenolic amine resin system with more reactive functional groups (-OH) enhances the fiber-resin bonding, further improving the tensile properties of GFRP. The enhancement mechanism of the multiphase structure in GFRP was elucidated by microscale characterization, indicating that the multiphase structures in GFRP, enhanced by SCA, nanomaterials, and functional curing agents, significantly improve its tensile properties.

Novel sustainable techniques for enhancing shear strength of RC beams mitigating construction failure risk

The aim of this study is to evaluate the effectiveness of various innovative and sustainable methods for improving the shear performance of reinforced concrete (RC) beams. The potential risk of failure for such elements is considered a potential threat, therefore, this study addresses it through experimental tests and numerical analyses to be mitigated carefully in order to enhance the safety and sustainability of buildings. A total of eleven specimens, comprising two control specimens and nine strengthened specimens, underwent three-point testing. Several proposed strengthening techniques, each involving multiple parameters, were examined. In the initial approach, glass fiber-reinforced polymer (GFRP) textile embedded in an external fiber-reinforced cementitious mortar (FRCM) jacket was utilized, with an evaluation of the number of the GFRP textile layers (1, 2, and 3 layers). The second technique incorporated near surface mounted (NSM) GFRP bars along with the FRCM jacketing, where the diameter of the GFRP bars (10, 12, and 16 mm) served as the primary parameter. In the final technique, externally bonded stainless-steel strips (SSSs) of varying thicknesses (1, 1.25, 1.50 mm) were affixed to the beams’ surface. The obtained results revealed that the application of the FRCM jacketing method yielded positive results, showing a significant 30.7 % average increase in the crack initiation load and a 17.1 % improvement in the failure load compared to the defected beam. However, issues of debonding beneath the loading point were observed in the FRCM jacket, particularly with three layers of the GFRP textile, leading to the separation of the concrete cover. Moreover, combining the NSM GFRP bars with an FRCM jacket addressed the absence of shear stirrups. The most remarkable improvement was noted utilizing the NSM GFRP bars and an FRCM jacket, followed by employing SSSs with an FRCM jacket.

Mechanical and thermal properties of glass fiber reinforced polymer-clay nanocomposites

Abstract The effect of Montmorillonite (MMT) nanoclay on static mechanical and thermal characteristcs of glass fiber-reinforced polymer (GFRP) composites is studied. The static tensile properties of epoxy/MMT nanoclay, which are important properties of GFRP composites, are investigated. The predicted stress-strain curves of epoxy with 0 and 1 wt.% of nanoclay follow experiments. The predicted elastic modulus and tensile strength of epoxy with 3 wt.% of nanoclay are 74 and 230% higher than neat epoxy. For GFRP composites with 0, 1, 3, and 5 wt.% of MMT nanoclays, the measured tensile strengths are 587, 600, 628, and 724 MPa, and flexural strengths are 626, 726, 906, and 542 MPa. For composites with former nanoclays, interlaminar shear strengths are 23, 25, 31, and 28 MPa, and Izod impact strengths are 83, 94, 207, and 145 kJ/m2. Thus, mechanical strengths of composites with 0–5 wt.% of nanoclays improve considerably than pristine sample. The predicted static tensile stress-strain curves of GFRP composites with above nanoclays follow experimental behavior. For GFRP composites with 0 and 1 wt.% of MMT nanoclays, glass transition temperatures are 91 and 101°C, and storage moduli at ambient temperature are 35 and 41 GPa. The thermal conductivities of GFRP composites with 0, 1, and 3 wt.% of MMT nanoclays at ambient temperature are 0.32, 0.36, and 0.42 W/(m·K). Thus, thermal properties of composites are affected significantly on addition of nanoclays.

Performance of GFRP Sheets in Strengthening Concrete Beams in Flexure

Plain concrete beam repair and strengthening are increasingly important in structural strengthening and retrofitting. This study examines the glass fibre-reinforced polymer (GFRP) sheets in plain concrete beams under flexural behaviour by using its patching sheets. Through the implementation of a symmetrical four-point static loading technique, a series of tests were conducted on plain concrete beams that had been externally joined with GFRP sheets. These beams were subjected to rigorous testing until they reached their ultimate failure point. The experimental test consists of casting nine plain concrete beams with identical specifications. Three beams are utilised as control beams; three are reinforced with GFRP sheets measuring 50 mm × 100 mm, and another three are reinforced with GFRP sheets measuring 100 mm × 200 mm. The flexural test is designed to determine the tensile strength of concrete under bending. Compared to the control beams, the specimens strengthened with GFRP sheets demonstrated a significantly enhanced ultimate load capacity. The beams with larger GFRP sheets exhibited a higher ultimate load of 14.84 kN, while those with smaller sheets showed an ultimate load of 8.54 kN, marking an appreciable improvement in performance. Moreover, the smaller area GFRP-reinforced beams failed at a 45% higher shear stress compared to those with a larger area GFRP, indicating a differential impact based on the size of the reinforcement used. This study highlights the effectiveness of GFRP sheets in enhancing the structural performance of plain concrete beams, providing crucial insights into the benefits of different sizes of reinforcement.

Experimental behaviour, FE modelling and design of large-scale reinforced concrete deep beams shear-strengthened with embedded fibre reinforced polymer bars

Reinforced concrete (RC) deep beams are widely used in buildings and bridges. However, research on shear strengthening of RC deep beams with embedded fibre reinforced polymer (FRP) bars is limited. This paper presents the first comprehensive study on the experimental behaviour, nonlinear finite element (NLFE) modelling and design of large-scale RC deep beams strengthened in shear with embedded carbon or glass FRP (CFRP or GFRP) bars. An experimental investigation comprising three large-scale RC deep beams was conducted. Subsequently, a three-dimensional NLFE model was developed and validated against the experimental results. The validated NLFE model was used to perform a parametric study, examining the influence of FRP bar type and steel-to-FRP shear reinforcement ratio on shear strength enhancement. The results of the parametric study were utilized to calibrate and validate a novel design model. The results showed that embedded FRP bars can enhance the shear force capacity of large-scale RC deep beams by up to 40 %. The effect of FRP bar type on the shear strength enhancement was insignificant. However, there was 13 % reduction in shear force gain due to the increase in steel-to-FRP shear reinforcement ratio from 0.77 to 10.0. The novel design model reproduced the NLFE results with a mean ratio of 0.921 and a standard deviation of 0.018. Finally, the ability of the design model to capture the effect of the investigated parameters was demonstrated.

Examining thermogravimetric response and morphological alterations in epoxy composites with hybrid ceramic fillers integration

The investigation explores thermogravimetric (DTA/(mW/mg) and TG%) analysis and morphological traits of glass fibre-reinforced epoxy polymer matrix composites (GFRP) incorporating ball-milled ceramic fillers. ZrSiO4, TiO2, FeTiO3, and SiO2 fillers, at varying weight proportions (0:0, 2.5:2.5, 5:5 and 7.5:7.5 wt %) are blended with epoxy using liquid ultrasonication and compression molding to make composites. Ceramic fillers expedite onset of thermal degradation, elevate DTG peak temperature and enhance thermal stability compared to plain GFRP. The composites exhibit significant weight loss between 341.1 °C and 348.4 °C. Epoxy/E-glass fibre composite with 5:5 wt % fillers demonstrates superior thermal and structural characteristics compared to pristine sample.

Experimental and numerical investigations on the axial compression performance of precast geopolymer concrete sandwich wall panel

This paper investigated a novel precast concrete sandwich panel (PCSP) which made by the geopolymer concrete and enabled by the glass fiber reinforced polymer (GFRP) hexagonal tube connector. Six precast geopolymer concrete sandwich wall panel (PGCSP) specimens were fabricated and tested under axial compression load. The investigating parameters included the connector spacing, panel height, and panel thickness. The failure mode, axial load capacity, load-axial deflection relationship, and load-concrete strain relationship were studied and discussed. Moreover, two-dimensional (2D) finite-element (FE) analysis was conducted to reproduce the test. Parameter analysis was then performed to modify the axial load capacity formula in the Chinese code GB50010-2010. The results indicated that: all specimens exhibited large eccentric compression failure due to the second-order effect, which was caused by concrete crushing and horizontal cracking in the two wythes, respectively; with the decrease of the connector spacing, the crushing area of the specimens would be enlarged, the out-of-plane lateral deformation would be decreased, and the axial load capacity decreased by 17 % and 42 % when the connector spacing changed from 300 mm to 600 mm and 900 mm, respectively; with the decrease of the panel height and the increase of concrete wythes thickness, the axial load capacity of the specimens almost presented a linear increase; the established 2D FE model and the modified formula effectively reflected the axial load capacity of the specimens.

Flexural Improvement of RC Slabs by FRP or Steel Using Different Strengthening Systems and Novel Anchoring Techniques

An experimental study on reinforced concrete one-way slabs strengthened by various methods and materials is introduced in this paper. Innovative anchorage procedures are presented and evaluated to prevent the strengthening elements with FRP system from de-bonding at the initial stages. Externally bonded embedded in concrete cover (EBECC) strengthening technology was proposed to save the fiber strips from being subjected to heat, degradation, and sabotage. Nine RC one-way slabs, including a control slab and eight strengthened slabs, were cast. One RC slab was strengthened using externally bonded embedded in concrete cover (EBECC), whereas the other tested RC slabs were strengthened using either externally bonded (EB) or near-surface mounted (NSM) procedures. The following test variables are used in this study: the proposed anchors, the area of steel, the kind of material utilized in NSM rods (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), and steel), and the strengthening scheme. The ultimate and initial cracking loads, load–deformation response, cracking patterns, and failure behavior were recorded and discussed. Additionally, a comparison of the stiffness, ductility, and energy absorption of the examined slabs was reported. The strengthened slabs by various techniques showed a boost in flexural strength that varied from 67 to 107% compared to the control slab. In addition, RC slabs strengthened by NSM-CFRP bars showed a maximum flexural capacity when compared with slabs strengthened by GFRP and steel bars. Also, the results supported the superiority of a novel end anchorage. The ABAQUS program was employed to conduct a finite element analysis (FEA) employing 3-D geometries to compare and assess the numerical performance of the identical slabs under similar test settings. The results showed good agreement between the experimental and numerical findings.

Durability of partially cured GFRP reinforcing bars in alkaline environments with or without sustained tensile load

Corrosion of steel reinforcing bars (rebars) in reinforced concrete structures can be addressed by using corrosion-resistant materials like Fiber-Reinforced Polymers (FRP). However, in France, FRP rebars are primarily restricted to temporary applications due to lack of comprehensive durability data. While numerous studies have explored FRP durability in alkaline environments, understanding the combined effect of alkali ions and sustained loading remains limited. Furthermore, the impact of incomplete matrix curing on the long-term performance of FRP rebars is limited.Accordingly, this paper investigates the durability of Glass FRP (GFRP) rebars exposed to alkali environments at varying temperatures. A batch of partially cured rebars was selected for this study, with part of them undergoing post-curing to investigate the effect of curing state on the ageing behaviour. Additionally, some partially cured specimens were subjected to combined sustained tensile loading at 20 % and 40 % of ultimate strength. Mechanical, physico-chemical and microstructural characterizations were conducted after various exposure durations. Results revealed that incomplete curing minimally impacted long-term tensile properties but significantly affected the interlaminar shear strength of aged rebars. Moreover, applying a combined load had little influence on residual properties at 20°C but led to rapid reduction in GFRP residual tensile strength at higher ageing temperatures (40 and 60°C).

Seismic retrofit of intact and damaged RC columns using prefabricated steel cage-reinforced UHPC jackets and NSM GFRP bars

The use of high-performance materials, such as ultra-high-performance concrete (UHPC) and fiber-reinforced polymer (FRP), in the seismic retrofitting and strengthening of reinforced concrete (RC) columns has attracted wide attention. In this study, a novel prefabricated steel cage-reinforced UHPC jacket (PSRUJ) was proposed to improve the retrofitting efficiency of conventional cast-in-place UHPC jackets and combine the advantages of UHPC and steel jackets. PSRUJ was further combined with the near surface-mounted (NSM) technique to develop a new method for retrofitting the seismic performance of RC columns in buildings. To investigate the effectiveness of the proposed retrofitting method, cyclic loading tests were performed on one intact RC column retrofitted with PSRUJ and two damaged RC columns retrofitted with PSRUJ and the combination of PSRUJ and NSM glass FRP (GFRP) bars. After PSRUJ retrofitting, the load-carrying capacity, deformation capacity, and stiffness of the intact and damaged RC columns increased by (30∼46)%, (54∼74)%, and (24∼40)%, respectively. The inclusion of NSM GFRP bars further increased the load-carrying capacity but reduced the residual drift ratio while having little effect on the ultimate drift ratio of the retrofitted columns. Further, a damage index was proposed to assess the damage degree of core normal concrete and develop the peak strength and strain models for PSRUJ-confined damaged concrete. Finally, a flexural strength model was proposed for damaged RC columns retrofitted with PSRUJ and NSM bars.

Seismic Performance of Corroded ECC-GFRP Spiral-Confined Reinforced-Concrete Column.

Preventing corrosion in the steel reinforcement of concrete structures is crucial for maintaining structural integrity and load-bearing capacity as it directly impacts the safety and lifespan of concrete structures. By preventing rebar corrosion, the durability and seismic performance of the structures can be significantly enhanced. This study investigates the hysteresis behavior of both corroded and non-corroded engineered cementitious composite (ECC)-glass-fiber-reinforced polymer (GFRP) spiral-confined reinforced-concrete (RC) columns. Employing experimental methods and finite element analysis, this research explores key seismic parameters such as crack patterns, failure modes, hysteretic responses, load-bearing capacities, ductility, stiffness degradation, and energy dissipation. The results demonstrate that ECC-GFRP spiral-confined RC columns, compared to traditional RC columns, show reduced corrosion rates, smaller crack widths, and fewer corrosion products, indicating superior crack control and corrosion resistance. Hysteresis tests revealed that ECC-GFRP columns, at a 20% target corrosion rate, exhibit an enhanced load-bearing capacity, ductility, and energy dissipation, suggesting improved durability and seismic resilience. Parametric and sensitivity analyses confirm the finite element model's accuracy and highlight the significant influence of concrete compressive strength on load-bearing capacity. The findings suggest that ECC-GFRP spiral-confined RC columns offer promising applications in coastal and seismic-prone regions, enhancing corrosion resistance and mechanical properties, thus potentially reducing formwork costs and improving construction quality and efficiency.

Seismic testing and fragility analysis considering material strength uncertainty of 1100 kV GFRP composite power transformer bushing

Nowadays glass-fibre reinforced polymer (GFRP) composite insulators are widely employed in electrical equipment in substations. However, there is a scarcity of reports on seismic qualification of transformer bushings that adopt GFRP insulators. Thereby, this case implements shaking table tests on a 1100 kV GFRP composite power transformer bushing. The study analyses the acceleration responses and dynamic amplification effects, as well as the strain responses. The combined stresses at the vulnerable positions are computed to authenticate the seismic performance. Using a simulation model, the seismic fragility of the transformer bushing considering the material strength uncertainty is assessed and discussed. The results indicate that the GFRP composite bushing meets the requirements of the relevant code and its seismic performance is qualified under an artificial ground motion with PGAs of 0.6 g and 0.8 g. For a given factor of safety of 1.67, the bushing can sustain 0.4 g earthquakes with a failure probability near 0 and 0.8 g earthquakes with a failure probability<50 %. Controlling coefficient of variation of the GFRP material strengths is beneficial to decreasing seismic fragility of the transformer bushing within a specific PGA range. Weibull and Normal distributions for fitting the strength distributions of the GFRP materials have different impacts on the seismic fragility of the bushing, which should be given more attention in seismic design.

Thermoplastic bicomponent‐fibers for organosheets via inline polymerization

AbstractState‐of‐the‐art organosheets suffer from several shortcomings that limit their applicability in high‐performance materials, mainly due to the imperfect combination of glass fibers and polymer. To overcome these issues, a novel hybrid fiber is presented, in which every single filament consists of a glass core and an individual, thin, thermoplastic polymer coating. Those fibers can immediately be consolidated into organosheets, without the necessity of the critical combination step. Production is realized by an ultra‐rapid inline coating of the filaments, incorporated into a standard spinning system. This solvent‐free process is realized by coating of the fibers with a tailor‐made, monomeric precursor solution, which is radiation‐polymerized immediately after application. Within fractions of a second, the coating layer is thus solidified, before coiling of the hybrid fiber. Due to the very low thickness of the coating and specific formulation of the precursor, tackless layers can be achieved before the coiling, even at industrial spinning speeds.Highlights Glass fibers are coated with a thermoplast via in situ polymerization. A precursor is developed which polymerizes in 100 ms. Glass fibers are coated completely with thermoplast by using a UV tunnel. Spinning velocities of about 600 m/min can be achieved. Hybrid fibers are consolidated into glass fiber‐reinforced plastics (GFRP).

A statistical volume element-based procedure for the prediction of the mechanical and electrical response of an epoxy-PZT self-sensing layer for application in composite laminates

Structural Health Monitoring (SHM) techniques are being developed to continuously oversee defects in composite structures. Within this context, research is focusing on the development of new types of sensors with high sensitivity and proper integration in the laminate.In this work, the mechanical and electrical properties of a recently developed piezoelectric composite material made of a Lead Zirconate Titanate (PZT) powder embedded in an epoxy matrix are evaluated with finite element simulations of plane strain Statistical Volume Elements (SVEs). The homogenized properties are then implemented in a second finite element model of a composite specimen with the embedded self-sensing material and loaded in compression. The electrical sensitivity is evaluated as a function of the distance between the signal electrodes.The results show that the finite element models with the homogenized properties have decreasing sensitivity with increasing electrodes distance, in agreement with the experimental results from another work, in which Glass Fiber Reinforced Polymer (GFRP) laminates with the embedded piezoelectric composite are loaded in compression and tested for output signal.

Analysis of load and contact mechanic on the composite structural: case study on GFRP composite

When creating lightweight structures to lower the rail vehicle's overall weight, composite materials with fiber reinforcements are the material of choice. Because of its excellent strength, low weight, high durability, stiffness, damping ability, flexural strength, resistance to wear and tear, impact resistance, indentation resistance, and corrosion resistance, composite materials. This study proposes to analyze the load and contact mechanic on the glass fiber reinforced polymers (GFRP) composite structural under tensile and flexural load. Tensile load 17.490 N was applied in 2 model, with Tab and without Tab. The flexural loading 669 N was applied in 6 models with the 3-load types and 2-contact mechanic types. The stress values and locations of the proposed finite elements analysis (FEA) modeling results were verified through experiments for tensile loads and flexural loads. The FEA modeling of GFRP composites under tensile load with tabs and without tabs have same the maximum stress location. The location at the outer surface of the grip splitter line. The stress 107 MPa on the gauge length area of FEA modeling and the experimental are same. FEA modelling under flexural loads, when using bonded contact shows that the location and value of stress concentration is not same as experimental. Using frictionless contact model have the value and location of maximum stress same as experimental. The FEA model 5 with Face load and frictionless mechanical contact has the stress concentration that is closest to the experimental results. By considering the type of load applied to the surface and the frictionless contact mechanics, FEA modeling can be used to predict the behavior of composite structures under bending loads

Post-fire performance of GFRP reinforced concrete deep beams: experimental and numerical study

Fire resistance of Glass Fiber Reinforced Polymer (GFRP) reinforced concrete members is an important concern in concrete structures. The experimental study of the structural response of GFRP reinforced concrete deep beams exposed to the ISO 834 standard fire is presented in this paper. To this end, a number of 7 specimens including 2 control and 5 fired specimen, have been subjected to monotonic static loading after exposure to fire. Shear span-to-depth ratio (a/d), horizontal distributed web reinforcement, and concrete compressive strength were the primary variables in the experiments. The results showed that after exposure to fire, ultimate capacity of the members decreases; and no changes occur in the initial stiffness of the members. Furthermore, the failure mode of specimens becomes more brittle and less ductile. Additionally, increasing a/d results in a decrease in the load bearing capacity and a shift in failure mode from pure shear to more ductile modes. By comparing the crack widths at failure point, obtained from image processing, it was found that in the beams with the small a/d ratio which are more shear dominant, after fire exposure, the maximum width of the cracks decreases.

Surface Treatment Strategies and Their Impact on the Material Behavior and Interfacial Adhesion Strength of Shape Memory Alloy NiTi Wire Integrated in Glass Fiber-Reinforced Polymer Laminate Structures.

Over the past few decades, there has been a growing trend in designing multifunctional materials and integrating various functions into a single component structure without defects. This research addresses the contemporary demand for integrating multiple functions seamlessly into thermoplastic laminate structures. Focusing on NiTi-based shape memory alloys (SMAs), renowned for their potential in introducing functionalities like strain measurement and shape change, this study explores diverse surface treatments for SMA wires. Techniques such as thermal oxidation, plasma treatment, chemical activation, silanization, and adhesion promoter coatings are investigated. The integration of NiTi SMA into Glass Fiber-Reinforced Polymer (GFRP) laminates is pursued to enable multifunctional properties. The primary objective is to evaluate the influence of these surface treatments on surface characteristics, including roughness, phase changes, and mechanical properties. Microstructural, analytical, and in situ mechanical characterizations are conducted on both raw and treated SMA wires. The subsequent incorporation of SMA wires after characterization into GFRP laminates, utilizing hot-press technology, allows for the determination of interfacial adhesion strength through pull-out tensile tests.

Infusion of Thick-Walled Fiber Metal Laminates with Aligned Holes in the Metal Foils

The rotor blades of wind turbines are becoming increasingly longer, which increases the diameter at the blade connection. Transport problems are the result, as the rotor blades no longer fit under highway bridges, for example. The increase in diameter can be prevented by increasing the bearing strength of the laminate using fiber metal laminates (FMLs). Individual layers of fiber material are replaced by metal foils in FMLs. This work is focused on the infusion of thick-walled FMLs, with infiltration experiments being carried out in-plane and out-of-plane. For the out-of-plane infusion tests, the metal foils are perforated and it is investigated whether the holes should be arranged alternately or aligned in the metal foils. It has been shown that greater laminate thicknesses can be realized with aligned holes. For the determination of voids and dry-spots, the metal foils are treated with a release agent before infusion and after curing the laminate can be demolded ply by ply. The samples made of glass fiber-reinforced plastic (GFRP) and steel/aluminum measure 500 mm by 800 mm by 20 mm.

Strain Behavior of Short Concrete Columns Reinforced with GFRP Spirals

This paper presents a comprehensive study focused on evaluating the strain generated within short concrete columns reinforced with glass-fiber-reinforced polymer (GFRP) bars and spirals under concentric compressive axial loads. This research was motivated by the lack of sufficient data in the literature regarding strain in such columns. Five full-scale RC columns were cast and tested, comprising four strengthened with GFRP reinforcement and one reference column reinforced with steel bars and spirals. This study thoroughly examined the influence of various test parameters, such as the reinforcement type, longitudinal reinforcement ratio, and spacing of spiral reinforcement, on the strain in concrete, GFRP bars, and spirals. The experimental results showed that GFRP–RC columns exhibited similar strain behavior to steel–RC columns up to 85% of their peak loads. The study also highlighted that the bearing capacity of the columns increased by up to 25% with optimized reinforcement ratios and spiral spacing, while the failure mode transitioned from a ductile to a more brittle nature as the reinforcement ratio increased. Additionally, it is preferable to limit the compressive strain in GFRP bars to less than 20% of their ultimate tensile strain and the strain in GFRP spirals to less than 12% of their ultimate strain to ensure the safe and reliable use of these materials in RC columns. This research also considers the prediction of the axial load capacities using established design standards permitting the use of FRP bars in compressive members, namely ACI 440.11-22, CSA-S806-12, and JSCE-97, and underscores their limitations in accurately predicting GFRP–RC columns’ failure capacities. This study proposes an equation to enhance the prediction accuracy for GFRP–RC columns, considering the contributions of concrete, spiral confinement, and the axial stiffness of longitudinal GFRP bars. This equation addresses the shortcomings of existing design standards and provides a more accurate assessment of the axial load capacities for GFRP–RC columns. The proposed equation outperformed numerous other equations suggested by various researchers when employed to estimate the strength of 42 columns gathered from the literature.

Correction: Pour et al. Enhancing Flexural Strength of RC Beams with Different Steel–Glass Fiber-Reinforced Polymer Composite Laminate Configurations: Experimental and Analytical Approach. Infrastructures 2024, 9, 73

In the published publication [...]