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Background: Glass fiber-reinforced polymer (GFRP) bars offer a superior alternative to steel bars in concrete reinforcement but are associated with wider cracks and higher deformation rates. This study introduces a novel approach by combining steel fibers (SFs) and carbon nanotubes (CNTs) to address these drawbacks and enhance the performance of GFRP-reinforced concrete beams. The unique contribution of this study lies in the simultaneous use of SFs and CNTs, which has not been extensively investigated, particularly in the context of GFRP-reinforced concrete. The study involved testing three sets of nine specimens with different concrete mixtures and reinforcement forms. Results: The results showed that adding 0.04% CNTs by cement weight and 0.6% SFs by volume fraction significantly improved the mechanical performance of GFRP and steel reinforced beams. GFRP reinforced beams with CNTs and SFs exhibited a reduction in crack width, a 20% increase in load-carrying capacity, and a 25% reduction in deflection compared to reference specimens. Scanning electron microscope analysis further revealed that CNTs effectively enhanced tensile load transfer, improving flexural behavior of the beams. The finite element analysis using ANSYS confirmed the experimental findings, highlighting the improved stress distribution in the modified concrete mixtures. Conclusions: Incorporating SFs and CNTs in concrete significantly improves the mechanical performance of GFRP-reinforced beams, making them more durable and resilient. These findings suggest that the proposed approach can enhance the longevity and sustainability of concrete structures, particularly in dynamic load applications such as bridges and high-rise buildings. Further experimental and analytical studies are recommended to assess the practical implications and cost-effectiveness of these materials in large-scale construction projects. [ABSTRACT FROM AUTHOR]

In this study, the analysis of reinforced concrete (RC) beams strengthened with Fiber Reinforced Polymer (FRP) composites against bending and shear loads was carried out with the finite element technique, using ABAQUS software, which is widely used in simulating experimental circumstances in numerical studies. It has been reported that buildings in areas damaged by earthquakes are generally constructed using low-strength concrete and inadequate reinforcement. Additionally, construction errors also contribute to reducing the load-bearing capacity of structural elements. For this purpose, nine rectangular cross-section RC beams were experimentally constructed using low-strength concrete and inadequate bending and shear reinforcement. These beams were strengthened by wrapping them in different configurations with Carbon and Glass FRP (CFRP and GFRP) composites to resist shear and bending forces in both transverse and longitudinal directions, and their load-displacement curves were obtained. Subsequently, a three-dimensional Finite Element Model (FEM) was created to validate the experimental results. The FEM validation demonstrated high accuracy in replicating experimental outcomes, emphasizing the influence of mesh size, dilation angle, and concrete constitutive models on simulation fidelity. Parametric studies revealed that increasing longitudinal reinforcement diameters had minimal effect on load capacity but highlighted the critical role of transverse reinforcement, as reducing stirrup spacing significantly improved load-bearing capacity. GFRP-reinforced beams exhibited superior ductility and a 15% higher strength compared to CFRP, suggesting their suitability for applications demanding enhanced displacement capacity. Furthermore, the findings underline the need for refined FEM models to better capture inclined fiber orientations and optimize structural reinforcement strategies. [ABSTRACT FROM AUTHOR]

Glass Fiber-Reinforced Composite (GFRP) has found widespread use in engineering structures due to its lightweight construction, high strength, and design flexibility. However, pure GFRP beams exhibit weaknesses in terms of stiffness, stability, and local compressive strength, which compromise their bending properties. In addressing these limitations, this study introduces innovative square GFRP beams infused with gypsum-based composites (GBIGCs). Comprehensive experiments and theoretical analyses have been conducted to explore their manufacturing process and bending characteristics. Initially, four types of GBIGC—namely, hollow GFRP beams, pure gypsum, steel-reinforced gypsum, and fiber-mixed gypsum-infused beams—were designed and fabricated for comparative analysis. Material tests were conducted to assess the coagulation characteristics of gypsum and its mechanical performance influenced by polyvinyl acetate fibers (PVAs). Subsequently, eight GFRP square beams (length: 1.5 m, section size: 150 mm × 150 mm) infused with different gypsum-based composites underwent four-point bending tests to determine their ultimate bending capacity and deflection patterns. The findings revealed that a 0.12% dosage of protein retarder effectively extends the coagulation time of gypsum, making it suitable for specimen preparation, with initial and final setting times of 113 min and 135 min, respectively. The ultimate bending load of PVA-mixed gypsum-infused GFRP beams is 203.84% higher than that of hollow beams, followed by pure gypsum and steel-reinforced gypsum, with increased values of 136.97% and 186.91%, respectively. The ultimate load values from the theoretical and experimental results showed good agreement, with an error within 7.68%. These three types of GBIGCs with significantly enhanced flexural performance can be filled with different materials to meet specific load-bearing requirements for various scenarios. Their improved flexural strength and lightweight characteristics make GBIGCs well suited for applications such as repairing roof beams, light prefabricated frames, coastal and offshore buildings. [ABSTRACT FROM AUTHOR]

This paper presents a study on manufacturing a range of hybrid laminated structures made of thermoplastic polyurethan (TPU), glass fibre reinforced plastic (GFRP), styrene-butadiene rubber (SBR) and metal mesh materials, and further on investigating the structural response of the TPU based composite sandwich laminated structures. These laminated structures were tested under quasi-static perforation and low velocity impact loading to determine their structural responses and energy absorption characteristics. It has been shown that three-layer and five-layer laminates with lay-ups of GFRP-TPU-GFRP or TPU-GFRP-TPU and GFRP-TPU-GFRP-TPU-GFRP or TPU-GFRP-TPU-GFRP-TPU subjected to quasi-static perforation demonstrate an increased peak load and stiffness with the core thickness from 1 to 4 mm. Also, the TPU core laminates show a superior ductility in comparison to their GFRP core counterparts. The energy absorption values of the three-layer and five-layer TPU and GFRP based laminated structures under low velocity impact are higher than those under quasi-static loading due to strain-rate effect. However, the hybrid laminates with SBR and wire mesh as a core do not give much improvement on the impact perforation resistance of the laminates with the different size of wire mesh, as metal mesh plays a less important role in the laminated structures to resist perforation. In overall, TPU-GFRP-TPU-GFRP-TPU structure with 4mm thick GFRP core demonstrates the highest peak force, and the GFRP-TPU-GFRP-TPU-GFRP structure with 4mm thick TPU core offers the highest energy absorption. [ABSTRACT FROM AUTHOR]

This study investigates the influence of various transverse reinforcement configurations on the torsional performance of glass fiber reinforced plastic (GFRP) reinforced concrete beams. A comprehensive experimental investigation includes five specimens, each characterized by unique transverse reinforcement designs in terms of stirrup spacing and inclination angles. The implementation of transverse torsional reinforcements within the beams exhibited a remarkable post-cracking hardening response, contributing to enhanced strength recovery. The experimental findings are subsequently compared with a reliable three-dimensional finite element model developed using the ABAQUS software. Finally, a parametric study is conducted to examine the influence of concrete and GFRP bar strength, along with longitudinal and transverse reinforcement ratios, on the torsional behavior of GFRP reinforced concrete beams. The results emphasize the significant impact of concrete tensile strength and transverse reinforcement on the cracking torque, while the parameters related to longitudinal reinforcement have only marginal effects. [ABSTRACT FROM AUTHOR]

Concrete columns with hollow-core sections find widespread application owing to their excellent structural efficiency and efficient material utilization. However, corrosion poses a challenge in concrete buildings with steel reinforcement. This paper explores the possibility of using glass fiber-reinforced polymer (GFRP) reinforcement as a non-corrosive and economically viable substitute for steel reinforcement in short square hollow concrete columns. Twelve hollow short columns were meticulously prepared in the laboratory experiments and subjected to pure axial compressive loads until failure. All columns featured a hollow square section with exterior dimensions of (180 × 180) mm and 900 mm height. The columns were categorized into four separate groups with different variables: steel and GFRP longitudinal reinforcement ratio, hollow ratio, spacing between ties, and reinforcement type. The experimental findings point to the compressive participation of longitudinal GFRP bars, estimated to be approximately 35% of the tensile strength of GFRP bars. Notably, increasing GFRP longitudinal reinforcement significantly improved the ultimate load capability of hollow square GFRP column specimens. Specifically, elevating the ratio of GFRP reinforcement from 1.46% to 2.9%, 3.29%, 4.9%, and 5.85% resulted in axial load capacity improvements of 32.3%, 43.9%, 60.5%, and 71.7%, respectively. Specifically, the GFRP specimens showed a decrease in capacity of 13.1%, 9.2%, and 9.4%, respectively. Notably, the load contribution of steel reinforcement to GFRP reinforcement (with similar sectional areas) was from approximately three to four times the axial peak load, highlighting the greater load participation of steel reinforcement due to its higher elastic modulus. In addition, the numerical modeling and analysis conducted using ABAQUS/CAE 2019 software exhibited strong concordance with experimental findings concerning failure modes and capacity to carry axial loads. [ABSTRACT FROM AUTHOR]

To promote the application of molybdenum tailings as the fine aggregate in concrete in construction engineering and verify the feasibility of fiber-reinforced polymer (FRP) material for strengthening molybdenum tailings concrete columns, this study takes a short circular molybdenum tailings concrete column reinforced by glass FRP (GFRP) as the research object. The influences of the molybdenum tailings content (0%, 25%, 50%, 75%, and 100%), the concrete grade (C30, C40, and C50), and the layer number (0, 1, and 2) of the GFRP sheet on the axial compressive capacity of the molybdenum tailings concrete column are investigated. The experimental phenomena and failure modes of the unreinforced and GFRP-reinforced columns are analyzed. The axial compressive strengths of the unreinforced and GFRP-reinforced columns are then compared. The load–strain curve and load–displacement curve of typical molybdenum tailings concrete columns are presented. Subsequently, six classical strength models for FRP-reinforced concrete are used to calculate the axial compressive strength of the confined specimens. The results show that the best classical model has a predictive accuracy with an absolute relative deviation (ARD) of 8.5%. To provide a better prediction of the compressive strength of the GFRP-reinforced molybdenum tailings concrete column, the best classical model is further improved, and the ARD of the modified model is only 5.87%. [ABSTRACT FROM AUTHOR]

Compressive testing of specimens taken from relatively thin composite plates is difficult, especially due to the occurrence of buckling. To prevent buckling, the central portion of the specimens used for the compression test has smaller dimensions, and the specimens can be guided along their entire length. For these reasons, optical methods, such as digital image correlation (DIC), cannot be used for the compression test and strain rosettes cannot be glued onto the samples to determine Poisson's ratio. In this study, compression tests of a glass fiber-reinforced polymer (GFRP) were conducted using both the ASTM D695 (Boeing version) and a newly proposed method. The new method involves using special specimens that allow T-type rosettes to be bonded to determine Poisson's ratio, whose value of 0.14 was thus determined. SEM images of the failure surfaces were presented and interpreted. A finite element analysis (FEA) of the specimens tested in compression is also presented. The first analyzed case considers the homogeneous and orthotropic composite, loaded with a uniformly distributed force. The normal stress in the central section of the specimen, determined with FEA, has an error of 6.52% compared to that determined experimentally. Additionally, the strain in the center of the strain gauge, determined with FEA, has an error of 4.76% compared to the measured one. In the second case studied with FEA, the sample is loaded with a quasi-concentrated force, which can move in the direction of the symmetry axes of the cross-section, to study the effect of the eccentricity of the compression force on the state of stress. It was shown that the eccentricity of the force has a great influence: the stress distribution in the section of the specimen becomes strongly non-uniform. For a force eccentricity of 0.4 mm in the direction of the OX axis, the minimum stress decreases by 53.7%, and the maximum stress increases by 55.4%. In order to analyze the influence of some manufacturing defects, two other cases were analyzed by FEA, in which it was assumed that the thicknesses of the outer resin layers were modified, making them asymmetrical. For this final FEA, the specimen was considered to be composed of laminates. These results demonstrate the special attention that must be paid to the centric application of force in compression testing. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) strengthening materials on the static and dynamic behavior of reinforced concrete (R/C) beams subjected to progressive damage. Four identical beams, each strengthened with either GFRP or CFRP, are tested under a cyclic quasi-static loading pattern. Impact hammer tests are performed for undamaged states and various damage levels of the beams. The dynamic test data are analyzed using the Enhanced Frequency Domain Decomposition (EFDD) method to estimate the dynamic characteristics of the beams. In this context, the first three vibration modes in both vertical and horizontal directions are considered. Strengthening is applied to both pre-damaged and undamaged beams, enabling a comparison of their performance before and after the strengthening procedure. Beams strengthened with CFRP exhibit a higher load-bearing capacity and stiffness but also fail at lower displacement levels compared to those strengthened with GFRP, which demonstrate more ductile behavior. Furthermore, the modal frequency ratios indicate that the first vibration mode is more sensitive to damage than the second and third modes. This study highlights the effectiveness of both strengthening materials in enhancing the structural performance of both undamaged and damaged beams. [ABSTRACT FROM AUTHOR]

In this study, the analysis of reinforced concrete (RC) beams strengthened with Fiber Reinforced Polymer (FRP) composites against bending and shear loads was carried out with the finite element technique, using ABAQUS software, which is widely used in simulating experimental circumstances in numerical studies. It has been reported that buildings in areas damaged by earthquakes are generally constructed using low-strength concrete and inadequate reinforcement. Additionally, construction errors also contribute to reducing the load-bearing capacity of structural elements. For this purpose, nine rectangular cross-section RC beams were experimentally constructed using low-strength concrete and inadequate bending and shear reinforcement. These beams were strengthened by wrapping them in different configurations with Carbon and Glass FRP (CFRP and GFRP) composites to resist shear and bending forces in both transverse and longitudinal directions, and their load-displacement curves were obtained. Subsequently, a three-dimensional Finite Element Model (FEM) was created to validate the experimental results. The FEM validation demonstrated high accuracy in replicating experimental outcomes, emphasizing the influence of mesh size, dilation angle, and concrete constitutive models on simulation fidelity. Parametric studies revealed that increasing longitudinal reinforcement diameters had minimal effect on load capacity but highlighted the critical role of transverse reinforcement, as reducing stirrup spacing significantly improved load-bearing capacity. GFRP-reinforced beams exhibited superior ductility and a 15% higher strength compared to CFRP, suggesting their suitability for applications demanding enhanced displacement capacity. Furthermore, the findings underline the need for refined FEM models to better capture inclined fiber orientations and optimize structural reinforcement strategies.

Abstract Background Glass fiber-reinforced polymer (GFRP) bars offer a superior alternative to steel bars in concrete reinforcement but are associated with wider cracks and higher deformation rates. This study introduces a novel approach by combining steel fibers (SFs) and carbon nanotubes (CNTs) to address these drawbacks and enhance the performance of GFRP-reinforced concrete beams. The unique contribution of this study lies in the simultaneous use of SFs and CNTs, which has not been extensively investigated, particularly in the context of GFRP-reinforced concrete. The study involved testing three sets of nine specimens with different concrete mixtures and reinforcement forms. Results The results showed that adding 0.04% CNTs by cement weight and 0.6% SFs by volume fraction significantly improved the mechanical performance of GFRP and steel reinforced beams. GFRP reinforced beams with CNTs and SFs exhibited a reduction in crack width, a 20% increase in load-carrying capacity, and a 25% reduction in deflection compared to reference specimens. Scanning electron microscope analysis further revealed that CNTs effectively enhanced tensile load transfer, improving flexural behavior of the beams. The finite element analysis using ANSYS confirmed the experimental findings, highlighting the improved stress distribution in the modified concrete mixtures. Conclusions Incorporating SFs and CNTs in concrete significantly improves the mechanical performance of GFRP-reinforced beams, making them more durable and resilient. These findings suggest that the proposed approach can enhance the longevity and sustainability of concrete structures, particularly in dynamic load applications such as bridges and high-rise buildings. Further experimental and analytical studies are recommended to assess the practical implications and cost-effectiveness of these materials in large-scale construction projects.

In this research, the effects of imbedding steel wires into the polyurethane foam of GFRP/Foam sandwich panel under three-point bending has been investigated. For this reason, three samples of non-reinforced, reinforced with two wires above and below and reinforced with three wires above and below the foam inside the GFRP sandwich panel were manufactured by vacuum bagging and tested under three-point bending in order to measure the specific strength of each sample. Moreover, a finite element model (FEM) was utilized using the Abaqus/Explicit package to further observe and analyze the stresses inside the samples. The results showed that imbedding steel wire inside the foam of the GFRP sandwich panel increased the bending strength by 25.2% in the two wire and 56.75% in the three-wire sample and bending modulus by 51.8% in two and 86% in three wire sample respectively. Since the weight of the wires with respect to the whole structure in negligible, the specific bending modulus of the sandwich panel was also improved by 21% in two and 44.8% in the three-wire sample. Finally, the results obtained from the experiments showed to have a decent agreement with the simulated model.

Wood is a heterogeneous and anisotropic material, and its mechanical properties are different from other building materials. It is necessary to know the mechanical properties of wood materials in buildings, such as carriers, floor beams, roof timber, plywood roof covers, laminated beams, stair or wire poles, yacht poles, and furniture frames. Tensile strength is the resistance of wood material to two forces applied in opposite directions, trying to break and separate the fibers. This study aimed to determine the tension strength perpendicular to fibers of beech timber reinforced with basalt fiber-reinforced polymer (BFRP), glass fiber-reinforced polymer (GFRP), and plaster mesh (PSM). One component polyurethane (PUR-D4) and polyvinyl acetate (PVAc-D4) were used as the adhesive. The BFRP, GFRP, and PSM were added as one layer of reinforced materials. Experimental materials reinforced with BFRP, GFRP, and PSM were tested in the unreinforced locations, of reinforced lumber with BFRP, GFRP, and PSM. Tests were performed to investigate the tensile strength perpendicular to fiber (┴σt). The test results showed that the reinforcement process increased the (┴σ). The ┴σt value of samples reinforced with BFRP was 13%, 32%, and 66% higher than those reinforced with GFRP, unreinforced, and reinforced PSM, respectively. Accordingly, the BFRP shows potential to serve as an option for reinforced wood structural members.

Concrete columns with hollow-core sections find widespread application owing to their excellent structural efficiency and efficient material utilization. However, corrosion poses a challenge in concrete buildings with steel reinforcement. This paper explores the possibility of using glass fiber-reinforced polymer (GFRP) reinforcement as a non-corrosive and economically viable substitute for steel reinforcement in short square hollow concrete columns. Twelve hollow short columns were meticulously prepared in the laboratory experiments and subjected to pure axial compressive loads until failure. All columns featured a hollow square section with exterior dimensions of (180 × 180) mm and 900 mm height. The columns were categorized into four separate groups with different variables: steel and GFRP longitudinal reinforcement ratio, hollow ratio, spacing between ties, and reinforcement type. The experimental findings point to the compressive participation of longitudinal GFRP bars, estimated to be approximately 35% of the tensile strength of GFRP bars. Notably, increasing GFRP longitudinal reinforcement significantly improved the ultimate load capability of hollow square GFRP column specimens. Specifically, elevating the ratio of GFRP reinforcement from 1.46% to 2.9%, 3.29%, 4.9%, and 5.85% resulted in axial load capacity improvements of 32.3%, 43.9%, 60.5%, and 71.7%, respectively. Specifically, the GFRP specimens showed a decrease in capacity of 13.1%, 9.2%, and 9.4%, respectively. Notably, the load contribution of steel reinforcement to GFRP reinforcement (with similar sectional areas) was from approximately three to four times the axial peak load, highlighting the greater load participation of steel reinforcement due to its higher elastic modulus. In addition, the numerical modeling and analysis conducted using ABAQUS/CAE 2019 software exhibited strong concordance with experimental findings concerning failure modes and capacity to carry axial loads.

In this research, rice husk ash (RHA) and eggshell ash (EGA) were used as biogenic materials for total replacement of pure quartz (SiO2) and calcium oxide (CaO) respectively in the traditional 45S5 bioactive glass composition by powder metallurgy route. Body formulation with nominal composition 45% RHA (SiO2), 24.5 EGA (CaO), 24.5% Na2O and 6% P2O5 was composed. The batch material was properly mixed with addition of 2% PVA (Polyvinyl alcohol) as binder and compacted at 70 MPa to produce compact samples of 40 x 20 mm. The samples were then allowed to dry in an ambient temperature followed by sintering at 1000°C for 2 h, then allowed to cool to room temperature. Selected samples were immersed inside prepared simulated body fluid (SBF – pH 7.4) at 37 °C for 5, 9, and 18h respectively. Physical, microstructure and phase evaluation were conducted to examine the developed bio-ceramic. The results showed the bio-waste based 45S5 bioceramic has bulk density and porosity of 1.02 g/cm3 and 62% respectively while deposits of carbonate-hydroxyapatite were found to increase with immersion period showing good bioactivity and affirm that the developed bio-waste based bioceramics are bioactive and can find suitable application bone repair.

Abstract This article investigates the behavior of hybrid FRP Concrete-Steel columns with an elliptical cross section. The investigation was carried out by gathering information through literature and conducting a parametric study, which resulted in 116 data points. Moreover, multiple machine learning predictive models were developed to accurately estimate the confined ultimate strain and the ultimate load of confined concrete at the rupture of FRP tube. Decision Tree (DT), Random Forest (RF), Adaptive Boosting (ADAB), Categorical Boosting (CATB), and eXtreme Gradient Boosting (XGB) machine learning techniques were utilized for the proposed models. Finally, these models were visually and quantitatively verified and evaluated. It was concluded that the CATB and XGB are standout models, offering high accuracy and strong generalization capabilities. The CATB model is slightly superior due to its consistently lower error rates during testing, indicating it is the best model for this dataset when considering both accuracy and robustness against overfitting.

The automobile industry is exploring the use of HP-RTM (high-pressure resin transfer molding) for mass-producing glass fiber-reinforced plastic (GFRP) chassis parts to achieve weight reduction. In this process, dry fabric is used as a material. However, the fatigue endurance performance of these parts deteriorates due to the bobbin threads in the dry fabric. This study aims to propose a laminating method to prevent the deterioration of the durability of GFRP chassis parts with bobbin threads. Specimens were fabricated with different fiber volume fractions (Vf) and bobbin thread positions. After manufacturing, static properties were evaluated to compare the physical properties of each specimen, and the stress for fatigue durability evaluation was determined based on these static properties. Finally, fatigue endurance performance evaluations were conducted to determine the optimal lamination conditions for GFRP chassis parts. The results showed that for the three laminating methods applied in this study, an increase in Vf not only enhanced the static properties but also reduced waviness, as confirmed through OM images and changes in the slope of the stress–strain curve. Additionally, fatigue endurance tests revealed that, along with the improvement in waviness, adjusting the position of the bobbin threads—which negatively impact durability—resulted in an increase in fatigue endurance performance from approximately 67,000 cycles to about 870,000 cycles, an improvement of approximately twelve times. [ABSTRACT FROM AUTHOR]

The behaviour of lightweight concrete (LWC) edge column-slab connections reinforced with two types of flexural reinforcement glass fiber-reinforced polymer (GFRP) and steel bars with different ratios of shear reinforcement are investigated experimentally and analytically using ABAQUS software. The experimental protocol covered evaluation of eight slabs and edge columns measuring subjected to static loading. Slabs are evaluated as supported, free-standing at one edge, and the column connection is included. The slabs are divided into two groupings, with four slabs in each group. The first group was reinforced with steel flexural, while the second group was reinforced with GFRP reinforcement. Within each group, one slab lacked shear reinforcement, while the other was reinforced with a varying shear reinforcement ratio. A good agreement was found between the numerical FE model and experimental outcomes in most tested slabs. [ABSTRACT FROM AUTHOR]

The incorporation of filler materials to enhance the properties of fibre-reinforced plastics is a prevalent practise in materials science. Calcium carbonate is a commonly used inorganic filler in composite fabrication. Eggshell, a rich source of calcium carbonate, offers an organic alternative to conventional inorganic fillers. This study investigates the efficacy of different types of eggshells as filler materials. Three variants, viz., unhatched raw eggshell, unhatched boiled eggshell, and post-hatched eggshell, were used to fabricate composite variants, which were then subjected to mechanical characterization and compared with unfilled composites. The results indicated that composites filled with unhatched eggshells outperformed those with post-hatched eggshells. Tensile testing revealed a significant enhancement in the tensile properties of all eggshell-filled composites in comparison to the unfilled ones. The composite variant filled with unhatched raw eggshell filler showcased the utmost tensile modulus and strength, with a notable 36% improvement in comparison with the unfilled variant. Similarly, flexural tests demonstrated a 53% increase in flexural strength for unhatched raw eggshell-filled composites over unfilled composites. SEM imaging confirmed these findings by showing crack arrests, deviations, particle distribution, and strong interfacial bonding in the eggshell-filled composites. [ABSTRACT FROM AUTHOR]

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The detection of impact and depth defects in Glass Fiber Reinforced Polymer (GFRP) composites has been extensively studied to develop effective, reliable, and cost-efficient assessment methods through various Non-Destructive Testing (NDT) techniques. Challenges in detecting these defects arise from varying responses based on the geometrical shape, thickness, and defect types. Long Pulse Thermography (LPT), utilizing an uncooled microbolometer and a low-resolution infrared (IR) camera, presents a promising solution for detecting both depth and impact defects in GFRP materials with a single setup and minimal tools at an economical cost. Despite its potential, the application of LPT has been limited due to susceptibility to noise from environmental radiation and reflections, leading to blurry images. This study focuses on optimizing LPT parameters to achieve accurate defect detection. Specifically, we investigated 11 flat-bottom hole (FBH) depth defects and impact defects ranging from 8 J to 15 J in GFRP materials. The key parameters examined include the environmental temperature, background reflection, background color reflection, and surface emissivity. Additionally, we employed image processing techniques to classify composite defects and automatically highlight defective areas. The Tanimoto Criterion (TC) was used to evaluate the accuracy of LPT both for raw images and post-processed images. The results demonstrate that through parameter optimization, the depth defects in GFRP materials were successfully detected. The TC success rate reached 0.91 for detecting FBH depth defects in raw images, which improved significantly after post-processing using Canny edge detection and Hough circle detection algorithms. This study underscores the potential of optimized LPT as a cost-effective and reliable method for detecting defects in GFRP composites. [ABSTRACT FROM AUTHOR]

This article investigates the behavior of hybrid FRP Concrete-Steel columns with an elliptical cross section. The investigation was carried out by gathering information through literature and conducting a parametric study, which resulted in 116 data points. Moreover, multiple machine learning predictive models were developed to accurately estimate the confined ultimate strain and the ultimate load of confined concrete at the rupture of FRP tube. Decision Tree (DT), Random Forest (RF), Adaptive Boosting (ADAB), Categorical Boosting (CATB), and eXtreme Gradient Boosting (XGB) machine learning techniques were utilized for the proposed models. Finally, these models were visually and quantitatively verified and evaluated. It was concluded that the CATB and XGB are standout models, offering high accuracy and strong generalization capabilities. The CATB model is slightly superior due to its consistently lower error rates during testing, indicating it is the best model for this dataset when considering both accuracy and robustness against overfitting. [ABSTRACT FROM AUTHOR]

In coastal regions, the deterioration of structures and bridges due to environmental conditions and corrosion is a significant concern. To combat these issues, the use of corrosion-resistant materials like fiber-reinforced polymers (FRPs) materials, engineered cementitious composites (ECCs), and rubberized ECCs (RECC) shows promise as normal concrete (NC) alternatives by providing increased ductility and energy absorption properties. The effectiveness of confining concrete columns using GFRP tubes with ECC/RECC was assessed in this research by evaluating their performance through compression and push-out tests. The study explored key parameters such as GFRP tube thickness and the presence of shear connectors along the tube height, as well as examining various types of concrete. Additionally, a comprehensive parametric investigation utilizing finite element analysis (FEA) was conducted to analyze how different factors influence the behavior of confined concrete columns. These factors included the effect of GFRP tube thickness and diameter on the overall behavior of different types of confined concretes. The results demonstrate that GFRP tubes significantly enhance column capacity, while the presence of ECC/RECC exhibits even greater improvements in capacity, stiffness, and toughness compared to NC. This approach shows promise in reinforcing coastal infrastructure and addressing corrosion-related concerns effectively. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the nonlinear structural behavior of concrete deep beams internally reinforced with glass fiber-reinforced polymer (GFRP) reinforcing bars and containing a web opening of various sizes and locations within the shear span. Three-dimensional (3D) numerical simulation models were developed for large-scale GFRP-reinforced concrete deep beams (300 mm × 1200 mm × 5000 mm) with a shear span-to-depth ratio (a/h) of 1.04. Predictions of the numerical models were validated against published experimental data. A parametric study was conducted to examine the effect of varying the opening size and location on the shear response. Results of the numerical analysis indicated that the strength of the deep beam models with an opening in the middle of the shear span decreased with an increase in either the opening width or height. The rate of the strength reduction caused by increasing the opening height was, however, more significant than that produced by increasing the opening width. Placing a web opening in the compression zone close to the load plate was very detrimental to the beam strength. Conversely, a negligible strength reduction was recorded when the web opening was placed in the tension side above the flexural reinforcement and away from the natural load path. Data of the parametric study were utilized to introduce simplified analytical formulas capable of predicting the shear capacity of GFRP-reinforced concrete deep beams with a web opening in the shear span. [ABSTRACT FROM AUTHOR]

The present study describes the energy absorption and damage analysis of the spherical core sandwich structures (SCSS) fabricated using woven Glass Fibre Reinforced Plastic (GFRP) by hand- layup method. Based on the core orientation, the spherical cores are categorized as stagger (S), regular (R), inverted (I), and interlock (L). The pitch distance and diameter of the models considered for the study are 24 mm and 16 mm, respectively. The specimens are subjected to a low velocity impact test (LVIT) at three different energy levels 9.9, 27.5, and 53.9 J respectively. Evaluations are carried out on the different kind of parameters namely coefficient of restitution (COR),energy absorption ratio, and energy loss percentage maximum displacement, maximum force, absorbed energy, and rebound energy. Among the models at every impact velocity it is found that the model R sustains a maximum force of 3078 N at 7 m/s impact velocity. The stagger model has recorded a maximum displacement of 34.4 mm among all velocities, whereas the regular model reveals a minimum displacement of 4.9 mm based on the analysis of maximum displacement. Similarly, the regular model has a maximum energy absorption ratio at 5 and 7 m/s respectively, whereas at 3 m/s the interlock model absorbs more energy. The failure pattern of the specimens is analyzed through visual inspection and ultrasound testing. Matrix cracking and fibre breakage are the typical failures seen in the model at 3 m/s, while core crushing and perforation are seen at 5 and 7 m/s impact velocities. The damage area is minimum for the interlock model whereas it is maximum for the stagger model.

This paper experimentally investigated the monotonic and cyclic behaviour of one-way basalt and glass fibre-reinforced polymers (BFRP and GFRP) reinforced concrete (RC) slabs compared with that of traditional steel RC ones. A total of nine 2000×700×100 mm RC slabs, including three BFRP RC (BRC), three GFRP RC (GRC), and three steel RC (SRC) slabs, were tested. The results indicated that the behaviour of BRC and GRC slabs was governed by the elastic characteristic of FRP bars, resulting in a more uniform curvature of the slabs. The behaviour and failure modes of BRC and GRC slabs were comparable with those of SRC slabs. The similarity and difference were characterized by the rupture of FRP bars and the yielding of steel bars. Postcrack stiffness of BRC and GRC slabs was significantly lower than that of SRC slabs and was marginally affected by the effect of cyclic loading. The ultimate loads and ultimate deflections of BRC and GRC slabs were ∼2.0 and 1.6–2.0 times those of SRC slabs, respectively. Concepts of ductility, safety factor, and warning index were introduced and quantified for FRP RC slabs. BRC and GRC slabs had a significantly higher ductility (8.5–10.4) than SRC slabs (5.1–6.2), showing a highly ductile behaviour. SRC slabs had a safety factor of 1.0–1.1, while BRC and GRC slabs had a significantly higher safety factor of 3.8, showing their lower failure probability of BRC and GRC slabs when they are designed at a similar load as SRC slabs. The warning index of SRC slabs was 14.4–30.2, and that of BRC and GRC slabs was 65.1–71.6 and 63.9–86.0, respectively. The strength, ductility, safety factor, recovery, and warning index of BRC and GRC slabs were high, confirming their advanced characteristics. Under cyclic loading, BRC and GRC slabs have significantly larger stiffness degradations (4.4 %–7.2 %/cycle) than SRC slabs (1.62 %−3.2 %/cycle). The results of theoretical analyses showed that the strengths of BRC and GRC slabs can be reasonably predicted. The outcomes indicate the high potential use of FRP reinforcement for slabs in engineering practice.

This study evaluated the uniaxial tensile strength and bond performance of natural hybrid reinforcement bars. Hybrid FRP combines multiple fibers and matrixes, resulting in a desirable performance. Two types of hybrid bars were tested: one with natural fibers surrounded by glass fiber, and the other with a steel core surrounded by natural fiber and then glass fiber. Thirteen samples were used to assess tensile behavior, with four groups including glass fiber, flax, sisal, and jute fibers. Pull-out behavior testing was conducted on twelve samples, divided into four groups of fiberglass, flax, sisal, and jute. Each group used three types of concrete: normal, high strength, and ultra-high-performance concrete (UHPC). The results refer to flax samples that had a higher tensile strength and elastic modulus of 143 MPa and 38 GPa, respectively, than samples made of sisal and jute fibres. The hybrid bars with a steel core exhibited a significant improvement in elastic modulus of 206 % in compared to samples made solely from glass, sisal, and jute fibers. On the other hand, the samples with UHPC showed the highest bond strength. The sample U-GFRP with ultra-high-performance concrete showed the highest bond strength 9.32 MPa, while the sample N-GFRP with normal concrete showed the lowest bond strength 5.87 MPa, respectively. However, this study suggests that hybridizing natural fibers can be a cost-effective and eco-friendly alternative to synthetic fibers.

Abstract E‐glass fibers are widely preferred due to ease of processing and its low cost, which has substantial scope in the fields of electronics and electrical insulation applications. Because of its low strength and corrosion resistance, use of E‐glass fibers is limited in aerospace and automotive applications. There is a need for enhancing the properties of the composite to overcome such limitations. Therefore, an attempt is made to introduce multi‐walled carbon nanotubes (MWCNT) as fillers into E‐glass fibers to meet the industry needs. In the current study, woven glass fiber of 5 layers and multi‐walled nano carbon fillers of 2, 4 and 6 by wt%, LY556 epoxy resin, and HY951 hardener were used to prepare 4 different type of composites along with the neat epoxy glass fiber reinforced polymer composites (GFRP). The hand‐layup route was used in the composite preparation due to its low cost, technological feasibility, and simple process setup. The developed samples were characterized for mechanical properties via tensile, flexural and impact tests. Tribological characteristics were performed by air jet erosion test. Chauvenet's criterion is applied for identifying the outliers (if any) from the data of repeated test properties. Taguchi's L9OA (orthogonal array) is selected for obtaining optimal hybrid composite, which yield better mechanical properties. Empirical relations are developed for the material properties in terms of process variables. The sample (4 wt% MWCNT) exhibited enhancement of 17.27% in tensile strength, 6% of impact strength and 7.3% of flexural strength when compared with neat epoxy GFRP. This hybrid composite is considered for thermal aging and observed at 60°C, 8% increase in tensile, 7% increase of impact and 15% in flexural strength due to the precipitation on carbon nano tubes along the gain boundaries. The present study recommends 4% MWCNT fillers in developing hybrid glass epoxy polymer composites for use in aerospace, automotive and civil construction industries due to economic and technological feasibility. Highlights Utilize low‐cost E‐glass fibers in electronics and electrical insulation applications. Improve composite properties for aerospace and automotive industries. Develop hybrid glass epoxy composites with 2 to 6 wt% MWCNT fillers. Examine wear characteristics under air jet erosion and study the impact of thermal aging on mechanical properties. Apply Chauvenet's criterion for outlier identification in measured properties datasets.

Abstract The current code provisions in ACI 440.11 are based on the flexural theory that applies to slender members and may not represent the actual structural behavior when the shear span-to-reinforcement depth ratio is less than 2.5 (i.e., deep members). The Strut-and-tie method (STM) can be a better approach to design deep members; however, this chapter is not included in the code. Research has shown that STM models used for steel-reinforced concrete (RC) give satisfactory results when applied to glass fiber-reinforced polymer-reinforced (GFRP)-RC members with a/d less than 2.5. Therefore, this study is carried out to provide insights into the use of STM for GFRP-RC deep members based on the available literature and to highlight the necessity for the inclusion of a new chapter addressing the use of STM in the ACI 440.11 Code. It includes a design example to show the implications of ACI 440.11 code provisions when applied to GFRP-RC deep members (i.e., isolated footings) and compares it when designed as per STM provided in ACI 318-19. It was observed that current code provisions in ACI 440.11 required more concrete thickness (i.e., h = 1.12 m) leading to implementation challenges. However, the required dimensions decreased (i.e., h = 0.91 m) when the design was carried out as per STM. Due to the novelty of GFRP reinforcement, current code provisions may limit its extensive use in RC buildings, particularly in footings given the water table issues and excavation costs. Therefore, it is necessary to adopt innovative methods such as STM to design GFRP-RC deep members if allowed by the code.

Purpose – This paper comprehensively addresses the influence of chopped strand mat glass fiber-reinforced polymer (GFRP) patch configurations such as geometry, dimensions, position and the number of layers of patches, whether a single or double patch is used and how well debonding the area under the patch improves the strength of the cracked aluminum plates with different crack lengths. Design/methodology/approach – Single-edge cracked aluminum specimens of 150 mm in length and 50 mm in width were tested using the tensile test. The cracked aluminum specimens were then repaired using GFRP patches with various configurations. A three-dimensional (3D) finite element method (FEM) was adopted to simulate the repaired cracked aluminum plates using composite patches to obtain the stress intensity factor (SIF). The numerical modeling and validation of ABAQUS software and the contour integral method for SIF calculations provide a valuable tool for further investigation and design optimization. Findings – The width of the GFRP patches affected the efficiency of the rehabilitated cracked aluminum plate. Increasing patch width WP from 5 mm to 15 mm increases the peak load by 9.7 and 17.5%, respectively, if compared with the specimen without the patch. The efficiency of the GFRP patch in reducing the SIF increased as the number of layers increased, i.e. the maximum load was enhanced by 5%. Originality/value – This study assessed repairing metallic structures using the chopped strand mat GFRP. Furthermore, it demonstrated the superiority of rectangular patches over semicircular ones, along with the benefit of using double patches for out-of-plane bending prevention and it emphasizes the detrimental effect of defects in the bonding area between the patch and the cracked component. This underlines the importance of proper surface preparation and bonding techniques for successful repair. Graphical abstract –

Buildings that require mechanical and electrical services must have utility pipes and ducts. The services include air conditioning, power supply, telephone lines, network cables, sewerage lines, water supply and etc. A reinforced concrete (RC) deep beam with web openings experiences excessive cracking and deflection, as well as a decrease in beam stiffness. Enlargement of these openings near supports would reduce beams’ capacity for shear. Hence, analysis and design of such beams require careful consideration, particularly with regard to their performance. In addition, design compliance to relevant codes and standards, and selection of suitable material properties and construction techniques are needed. When such an enlargement is unavoidable, strengthening of beam for shear and flexure is necessary. In this study, the use of GFRP (Glass-Fiber Reinforced Polymer) composites for strengthening of RC beams with openings is experimentally investigated. As compared to the control beam, test results showed that using GFRP was found to be effective in increasing the shear strength of beams with openings by 40% to 60%. Test results of beams with web openings exhibited higher shear strength than the predicted values whereas for strengthened beams with GFRP, code predictions are found conservative.

Introduction. Over the past decade, the share of concrete structures reinforced with composite polymer reinforcement (FRP) has increased, which is due, among other things, to the development of the regulatory and technical framework in this direction. The inherent features of FRP, largely determined by the properties of its components, which must be taken into account at all stages of construction and operation of the building, lead to some changes in the traditional approaches to the design of structures and the technology of their construction.Materials and methods. A review of domestic experience in the use of composite polymer reinforcement in the construction of monolithic concrete foundations is carried out. An example of design and construction solutions of a foundation plate is considered. On the basis of its analysis, the selection of reinforcement from FRP was carried out according to the results of calculations for the first and second groups of limit states.Results. Design features that should be taken into account when calculating foundation slabs made of concrete reinforced with FRP are indicated. The concrete example of a monolithic concrete foundation slab shows the effect of taking into account the actual mechanical characteristics of FRP on the results of strength and crack resistance calculations. The results of calculations carried out according to various editions of regulatory documents relevant for the period from 2014 to 2023 clearly demonstrate the development of the regulatory framework in terms of taking into account the FRP properties in reinforced concrete structures.Conclusions. With a rational approach to design processes, it is possible to develop projects of concrete foundation slabs on an elastic base using FRP that meet the requirements of regulatory documents on reliability. It is possible to completely exclude metal elements (fittings, products, embedded parts) in such structures.

The flexural and shear behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) reinforced with different ratios of glass-fiber-reinforced polymer (GFRP) and conventional steel rebars is experimentally studied in this paper. For this purpose, three beams with dimensions of 250×300×1650 mm were reinforced with GFRP rebars in three different ratios (0.64%, 1.05%, and 1.45%) and hooked-end (H) steel fibers by 2% volumetric ratio. Similar procedure was carried for beams reinforced with conventional rebars. Additionally, Nonlinear regression analyses were also carried out to simulate the flexural load-deflection behavior of the beams. Results showed that the role of hooked-end fibers in compensating for the brittle nature of GFRP rebars was insignificant. Besides, increase of the longitudinal reinforcement ratio changed the failure mode from flexural to shear failure in specimens with GFRP rebars. Finally, nonlinear regression models were proposed that successfully capture the load-deflection behavior of the test specimens with coefficient of correlation (R^2) very close to unity.

The current code provisions in ACI 440.11 are based on the flexural theory that applies to slender members and may not represent the actual structural behavior when the shear span-to-reinforcement depth ratio is less than 2.5 (i.e., deep members). The Strut-and-tie method (STM) can be a better approach to design deep members; however, this chapter is not included in the code. Research has shown that STM models used for steel-reinforced concrete (RC) give satisfactory results when applied to glass fiber-reinforced polymer-reinforced (GFRP)-RC members with a/d less than 2.5. Therefore, this study is carried out to provide insights into the use of STM for GFRP-RC deep members based on the available literature and to highlight the necessity for the inclusion of a new chapter addressing the use of STM in the ACI 440.11 Code. It includes a design example to show the implications of ACI 440.11 code provisions when applied to GFRP-RC deep members (i.e., isolated footings) and compares it when designed as per STM provided in ACI 318-19. It was observed that current code provisions in ACI 440.11 required more concrete thickness (i.e., h = 1.12 m) leading to implementation challenges. However, the required dimensions decreased (i.e., h = 0.91 m) when the design was carried out as per STM. Due to the novelty of GFRP reinforcement, current code provisions may limit its extensive use in RC buildings, particularly in footings given the water table issues and excavation costs. Therefore, it is necessary to adopt innovative methods such as STM to design GFRP-RC deep members if allowed by the code. [ABSTRACT FROM AUTHOR]

The drilling of composite structure leads to its damage, near the peripheral areas of the drilled hole, due to the laminar structure of the composites. The goodness of a drilling process can be evaluated by measuring the extent of the damage caused by it. In the present study, lock-in thermography non-destructive inspection method is proposed to characterise the drilling damages in glass fiber–reinforced polymer panel. A semi-automated image processing methodology is proposed to calculate damage parameters, namely delamination area and size, and delamination factor. The effect of excitation frequency on the damage characterisation is studied to decide the optimum frequency range to measure the damage parameters through signal-to-noise ratio and damage visibility. The damage parameters are measured at optimum frequency. The study showed that the lock-in thermography technique has the potential to characterise drilling damage. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) offer an alternative to traditional reinforced concrete columns for new construction applications due to their high strength, ductility, and corrosion resistance properties. Despite their popularity, there is a lack of accurate analytical models for the cyclic/seismic performance of CFFT columns. This is due to the absence of precise stress–strain models for FRP tubes and confined concrete under cyclic loading. Previous experiments on CFFT columns suggest that even minimal reinforcement (≤1%) provides essential energy dissipation for extreme events. However, existing stress–strain models for FRP-confined concrete often neglect the contribution of longitudinal and transverse steel reinforcement. While some researchers have proposed material models to address this issue, the analytical modeling of confinement effects from both steel reinforcement and FRP tubes, especially under lateral cyclic loading, continues to pose a significant challenge. This study aims to use previously collected experimental data to evaluate current analytical modeling approaches in OpenSeesPy3.5.1.12 to simulate the lateral cyclic behavior of CFFT columns with ±55° glass fiber-reinforced polymer (GFRP) fiber orientation. Both the lumped inelasticity and the distributed inelasticity modeling approaches are applied. The performance of various FRP confinement models is compared. The effect of plastic hinge length is also considered in the lumped plasticity approach. The findings suggest that integrating a fiber element section into the plastic hinge zone enhances the efficiency of the distributed inelasticity approach. This method accurately captures the non-linear behavior in the critical region and precisely predicts the shape of the hysteretic curve, all while reducing computational costs. Conversely, the lumped inelasticity modeling approach effectively forecasts energy dissipation and peak load values across the entire cyclic hysteresis curve, offering significant computational savings. Finally, a generalized modeling methodology for predicting the response of CFFTs under cyclic lateral load is proposed and subsequently validated using experimental results found in the existing literature. [ABSTRACT FROM AUTHOR]

In this research, the effects of imbedding steel wires into the polyurethane foam of GFRP/Foam sandwich panel under three-point bending has been investigated. For this reason, three samples of non-reinforced, reinforced with two wires above and below and reinforced with three wires above and below the foam inside the GFRP sandwich panel were manufactured by vacuum bagging and tested under three-point bending in order to measure the specific strength of each sample. Moreover, a finite element model (FEM) was utilized using the Abaqus/Explicit package to further observe and analyze the stresses inside the samples. The results showed that imbedding steel wire inside the foam of the GFRP sandwich panel increased the bending strength by 25.2% in the two wire and 56.75% in the three-wire sample and bending modulus by 51.8% in two and 86% in three wire sample respectively. Since the weight of the wires with respect to the whole structure in negligible, the specific bending modulus of the sandwich panel was also improved by 21% in two and 44.8% in the three-wire sample. Finally, the results obtained from the experiments showed to have a decent agreement with the simulated model. [ABSTRACT FROM AUTHOR]

E‐glass fibers are widely preferred due to ease of processing and its low cost, which has substantial scope in the fields of electronics and electrical insulation applications. Because of its low strength and corrosion resistance, use of E‐glass fibers is limited in aerospace and automotive applications. There is a need for enhancing the properties of the composite to overcome such limitations. Therefore, an attempt is made to introduce multi‐walled carbon nanotubes (MWCNT) as fillers into E‐glass fibers to meet the industry needs. In the current study, woven glass fiber of 5 layers and multi‐walled nano carbon fillers of 2, 4 and 6 by wt%, LY556 epoxy resin, and HY951 hardener were used to prepare 4 different type of composites along with the neat epoxy glass fiber reinforced polymer composites (GFRP). The hand‐layup route was used in the composite preparation due to its low cost, technological feasibility, and simple process setup. The developed samples were characterized for mechanical properties via tensile, flexural and impact tests. Tribological characteristics were performed by air jet erosion test. Chauvenet's criterion is applied for identifying the outliers (if any) from the data of repeated test properties. Taguchi's L9OA (orthogonal array) is selected for obtaining optimal hybrid composite, which yield better mechanical properties. Empirical relations are developed for the material properties in terms of process variables. The sample (4 wt% MWCNT) exhibited enhancement of 17.27% in tensile strength, 6% of impact strength and 7.3% of flexural strength when compared with neat epoxy GFRP. This hybrid composite is considered for thermal aging and observed at 60°C, 8% increase in tensile, 7% increase of impact and 15% in flexural strength due to the precipitation on carbon nano tubes along the gain boundaries. The present study recommends 4% MWCNT fillers in developing hybrid glass epoxy polymer composites for use in aerospace, automotive and civil construction industries due to economic and technological feasibility. Highlights: Utilize low‐cost E‐glass fibers in electronics and electrical insulation applications.Improve composite properties for aerospace and automotive industries.Develop hybrid glass epoxy composites with 2 to 6 wt% MWCNT fillers.Examine wear characteristics under air jet erosion and study the impact of thermal aging on mechanical properties.Apply Chauvenet's criterion for outlier identification in measured properties datasets. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]