유리와 탄소섬유로 제작된 하이브리드 FRP 로드의 인장특성에 관한 실험연구

The durability and lifespan of concrete structures are significantly affected by the corrosion of steel reinforcement. Though epoxy-coated steel reinforcement is being used for practical applications, slight damage in the coating during the construction process is enough to initiate the corrosion process. The shortcomings in the current practices to prevent corrosion of steel reinforcement have led the researchers to look for alternatives. Innovative hybrid reinforcing elements with solid steel core and fibre-reinforced polymer (FRP) wrapping (called steel–FRP composite bars (SFCB)) can be considered as a suitable alternative to conventional steel reinforcement. In this research paper, experimental and numerical studies that investigated the flexural behaviour of concrete beam specimens reinforced with SFCB produced using glass fibres or carbon fibres are presented and discussed. Experimental study consisted of flexural testing of six concrete beam specimens with conventional steel reinforcement or SFCB with glass fibres or SFCB with carbon fibres. Two different spacings of shear stirrups were considered. Failure mode, first crack load, ultimate flexural load and load-deflection behaviour were recorded during the experiment. The test results showed that beam specimens with SFCB reinforced achieved less ultimate flexural load as compared to beam specimens with conventional steel reinforcement. The failure mode was found to be influenced by the spacing of the shear stirrups. The results of the numerical analysis were close to the experimental results. .

Industry demands new engineering and material solutions. One of these solutions are fibre reinforced polymers. They are light and strong for application as a material for I-beams. An I-beam is the best section for a homogeneous material because of the highest resistance moment. The popularity of composite materials introduces wide use in most branches of engineering and mostly as fibre reinforced polymers (FRP). This paper presents numerical and analytical studies on the mechanical behaviour of the I-beams made of fibre reinforced polymers reinforced by glass fibres (GFRP) and carbon fibres (CFRP) comparing to the structural steel S235JR. Five I-beams with different composite structures and one steel I-beam were numerically tested. Four-point test according to ASTM C 78 – 02 was conducted. Numerical simulation made in SOLIDWORKS software in the Static simulation mode was used. The obtained results were analysed and an attempt to determine the optimal parameters for combination of different composite materials was conducted. As a result of numerical analysis values of deflection and normal stress were obtained for polymer I-beam reinforced by glass and carbon fibres comparing to the steel I-beam.

Fiber reinforced polymer (FRP) bars represent a combination of the polymer binder and reinforcing fibers (glass, basalt, aramid, carbon). The main features of FRP bars are high tensile strength on the background of the relatively low elasticity modulus. To prevent development of the excessive both crack opening and deflections in the FRP reinforced concrete structures it can be effective to implement FRP reinforcement pretensioning with a limited level of created stresses. As a good option can be considered a physico-chemical method of FRP bars pretensioning based on the self-stressing concrete utilizing. In the self-stressed FRP reinforced members it is possible to obtain a considerable values of the early age restrained expansion strains (in comparison with steel reinforced self-stressed members because of FRP bars lower elasticity modulus), which will not disappear after air-dry shrinkage strains realization. In addition, another concern that have to be considered in the field of FRP reinforced self-stressed members is bond performance of the different FRP bars types, especially in combination with self-stressing concrete that within its expansion can provoke decompacting of the transit zone «bar-concrete». Moreover, taking into account that FRP bars is a composite material, its bond properties are strongly influenced by the types of the polymer binder, reinforcing fibers, ratio between binder and fibers, bar coating. Presented studies is consisted in the experimental investigations of the features in the crack development and depended on it occurred failure mode of the self-stressed members reinforced by the different types of FRP bars.

Extensive research has led to a better understanding of the application of various corrosion protection methods in reinforced concrete (RC) structures and the use of fiber reinforced polymer (FRP) rebars is a typical example. However different fibres come along with different deficiencies, such as low elastic moduli and poor alkaline resistance in glass fibre (Saikia et al. 2007); brittle fracture and high cost in carbon fibre. Taking advantages of the strength of different fibres and the cost effectiveness of steel fibre, a hybrid composite rebar was recently developed. Steel fibers and glass fibers are distributed within the core, while aramid and carbon fibers created a shell for strength and corrosion protection. A series of concrete beams reinforced with the proposed hybrid rebars were tested and it was demonstrated that the beams have the ability to undergo large inelastic deformations, and the ductility indexes were found to be similar conventional steel-reinforced beams. Besides, accelerated alkaline ageing tests were performed using concrete pore solutions at different temperatures, and the service life and alkaline resistance of the proposed rebar were proven to be very good.

Fiber Reinforced Polymer (FRP) has been used as one of the repair or strengthening materials for deteriorated concrete structures. However, the elastic properties of FRP materials cause a limitations on the ductility of the reinforced concrete structure. This research focuses on the study of the behavior of reinforced concrete beams strengthened using a hybrid Carbon-Glass Fiber Reinforced Plastic (Hybrid FRP). Hybrid FRP is a combination of two layers of FRP that have different elastic modulus, namely Glass Fiber and Carbon Fiber. The objective of using hybrid composites is to obtain a combined elastic mode behavior from two kind of fibers. Flexural testing of reinforced concrete beams with FRP hybrid reinforcement was carried out to study the flexural behavior and also the effectiveness of strengthening. The test material is a reinforced concrete beam with dimensions of 150 mm x 200 mm x 3300 mm. Two types of beams were prepared, namely control beams (BN) and beams with FRP Hybrid strengthening (BGC). The composition of the FRP hybrid was 100% of Glass fiber and 40% of Carbon fiber to the width of the beam. The test results show that the beam with FRP hybrid strengthening has a moment capacity of 12% higher than the control reinforced concrete beam (BN). The mode of failure of the BN beams was the crushing of the concrete that was initiated by yielding of the steel reinforcement. For BGC beams, failure mode was in the form of debonding of the hybrid FRP layer.

The development and testing of a pseudoductile hybrid fiber-reinforced polymer rod consisting of glass and carbon fibers is described. Two different hybrid forms were considered for the development of the hybrid rods, including (1) random dispersion of the glass and carbon fibers; and (2) a core-shell design with a glass fiber core protected by the carbon fiber shells. The mechanical properties of the hybrids were evaluated through uniaxial tension tests. The hybrid rods developed by way of the core-shell approach exhibited pseudoductile properties that included a yield point of 1,153 MPa and an ultimate strength of 1,191 MPa, with a strain of 3.5% at ultimate. The experimental program also included damage assessment by way of a single-channel fiber optic acoustic emission (AE) sensor. The acoustic emission technique was employed for real-time determination of the progressive damage due to rupture of fibers. Moreover, the spectral energies of the frequency spectrum from the AE signals were employed for assessment of the state of damage in the rods. The spectral energies distinguish between the carbon and glass fiber ruptures. This differentiation of signals provides information about the condition and the state of health of the hybrid rod.

Carbon nanotubes (CNTs) and Carbon nanofilaments (CNFs) were grown on the surface of carbon and glass sheets from fuel rich ethylene/oxygen combustion mixtures on certain catalytic metals. Employing a well-known catalyst deposition method, incipient wetness allowed growing CNTs/CNFs on the surface of carbon and fiber glass bidirectional sheets. Two-layer fiber reinforced polymer (FRP) composite plates were fabricated using a vacuum assisted hand lay-up technique of the carbon and glass fiber sheets after CNTs/CNFs were grown using 1.0% Nickel deposits. In this paper we report on the growth process and we examine the significance of the CNTs/CNFs growth conditions including the sizing burning temperature (250 and 500 oC), the growth time period and the fiber base type (carbon or glass) on the strength and stiffness of this new multi-scale FRP composite. The ultimate tensile strength, tensile modulus (stiffness) and ultimate strain at failure was determined using ASTM D3039 test. It is shown that the sizing burning temperature has a significant effect on the strength and strain at failure of the new carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) composites. Little effect on the composite stiffness was observed. Microstructural investigations of the failed specimens shed light on the fracture surface of the multi-scale CFRP and GFRP composites.

FRP (fiber reinforced polymer) composite retrofit is a practical method for increasing the strength of historic URM buildings. Several materials for FRP upgrading are now available, including using FRP made of glass, aramid, basaltic, and carbon fiber, various resins such as epoxy, polyester, and vinyl ester. In addition to the choices for materials, different retrofit techniques are available, including externally bonded, near-surface mounted, and mechanically anchored FRP. Each of these has strengths and weaknesses for use in historic buildings, related to durability, mechanical compatibility, ease of installation, chemical suitability, seismic ductility, strength, reversibility, and cost. This paper will describe the differences between the various methods of FRP retrofit used for historic building strengthening, describe case studies of FRP installation and performance for historic buildings, and make recommendations for FRP retrofit in relation to the “Standards for Historic Preservation” by the National Park Service.

This study investigates the impact of fiber reinforcement, specifically carbon and glass fibers, on the flexural behavior and fracture performance of cementitious composites with varying strengths The strength grades of the composites were designated as high-strength, medium-strength, and low-strength. The composites were reinforced with woven glass and carbon fibers at different length/span ratios and subjected to flexural testing to evaluate key parameters such as strength, strain, and modulus. High, medium, and low-strength prism specimens were prepared using specific cement dosages (634.26 kg/m 3 for high strength, 535.26 kg/m 3 for medium strength, and 432.65 kg/m 3 for low strength) with corresponding water-to-cement ratios of 0.3, 0.4, and 0.65, respectively. The results indicate that fiber reinforcement significantly enhances the flexural properties of all composite categories, with the most notable improvements observed in the medium-strength and high-strength composites. Among the composites, the carbon fiber-reinforced high-strength composite (HS-CFRC-4/7) demonstrated the highest flexural strength (10.00 MPa), a 73% improvement over the control specimen. However, a diminishing return in strength gain was observed in high-strength composites, suggesting weaker anchorage bond between woven fiber and the specimen where the matrix strength becomes the dominant factor. Additionally, carbon fibers exhibited a higher strain capacity than glass fibers, with consistent increases in ductility across all composite groups. Fracture analysis revealed distinct failure modes, including flexural cracks, diagonal shear cracks, and delamination, especially in high-strength composites.

In the aircraft manufacturing industry, the strength and weight of the material is one of the important considerations in structural design. Composite material is a material composed of two or more forming materials, each of which has different mechanical properties. Aircraft structure in this era are 50 - 80% composed of glass or carbon fiber composite materials as reinforcement. Unfortunately, these fibers when recycled produce harmful CO gas, difficult to degrade naturally and cause itching when in contact with human skin. For this reason, environmentally friendly and strong fibers are needed to replace the role of glass or carbon fibers. Is a bamboo plant, which is abundant in Indonesia which is considered suitable as a substitute material. In this study, a mechanical test and descriptive analysis were carried out on the strength of the composite material with variations in the types of bamboo fibers apus, wulung, tutul and petung. These fibers are arranged with epoxy resin and hardener as a binding material (matrix). And each fiber will be arranged in 0 ° pattern to the matrix. Then each material with a different fiber type will be tested for tensile and bending to obtain the value of stress and strain that occurs at its maximum loading. And the result is the average tensile stress value (Mpa) composite material of apus bamboo is 75.95, wulung bamboo 49.92, petung bamboo 112.73, tutul bamboo 83.85. Then the average bending stress (Mpa) composite material of apus bamboo was 239.073, wulung bamboo 214.236, petung bamboo 249.67, tutul bamboo 272.79. With this result, bamboo fiber composites are considered to be able to replace the role of carbon or glass fibers, as an alternative composite material in some parts of the interior fuselage of aircraft panels. Keyword: Composites material, Matrix, Bamboo Fibers, Carbon and Glass Fibers, Stress and Strain.

One of the major advantages of fibre reinforced polymers (FRPs) is their high tensile strength and low weight to strength ratio. Compared to steel reinforcement, this is one of the main and decisive features that could determine the choice of materials used in the design. Since there is no corrosion for this type of reinforcement, it is very suitable for concrete structures in aggressive environments. This point, along with others, gives concrete structures reinforced with FRPs significant advantages over conventional concrete structures with steel reinforcement. Different material properties and behaviour of FRP when compared to steel reinforcement result in the need of the modification of established design procedures, especially in the area of the ultimate strain, because FRP reinforcement has a different σ-ε diagram than the steel reinforcement. The experimental verification of the new design procedures is necessarily needed. This paper summarizes the results of practical design and calculations of the resistance of alternatively steel and GFRP reinforced concrete ceiling slab of a garage house and experimental results on the beam specimens reinforced with GFRP reinforcement tested under four-points test. It was necessary to adjust the conventional procedures in calculating the required area of GFRP reinforcement in order to avoid brittle failure of the cross-section (rupture of reinforcement). This is ensured by abiding the balance reinforcement level. Another fact to be considered is the creep rupture phenomenon causing immediate rupture of GFRP reinforcement under a high level of sustained loading. The reduction of GFRP strength according to the long-term loading results in rising required area of reinforcement. Finally, the serviceability limit state is checked. According to the low modulus of elasticity of GFRP reinforcement, the deflection should be the limiting factor for the amount of reinforcement designed.

Purpose Building elements that are damaged by fire are often strengthened by fiber wrapping techniques. Self-compacting concrete (SCC) is an advanced building material that is widely used in construction due to its ability to flow and pass through congested reinforcement and fill the required areas easily without compaction. The aim of the research work is to examine the flexural behavior of SCC subjected to elevated temperature. This research work examines the effect of natural air cooling (AC) and water cooling (WC) on flexural behavior of M20, M30, M40 and M50 grade fire-affected retro-fitted SCC. The results of the investigation will enable the designers to choose the appropriate repair technique for improving the service life of structures. Design/methodology/approach In this study, an attempt has been made to evaluate the flexural behavior of fire exposed reinforced SCC beams retrofitted with laminates of carbon fiber reinforced polymer (CFRP), basalt fiber reinforced polymer (BFRP) and glass fiber reinforced polymer (GFRP). Beam specimens were cast with M20, M30, M40 and M50 grades of SCC and heated to 925ºC using an electrical furnace for 60 min duration following ISO 834 standard fire curve. The heated SCC beams were cooled by either natural air or water spraying. Findings The reduction in the ultimate load carrying capacity of heated beams was about 42% and 55% for M50 grade specimens that were cooled by air and water, respectively, in comparison with the reference specimens. The increase in the ultimate load was 54%, 38% and 27% for the specimens retrofitted with CFRP, BFRP and GFRP, respectively, compared with the fire-affected specimens cooled by natural air. Water-cooled specimens had shown higher level of damage than the air-cooled specimens. The specimens wrapped with carbon fiber could able to improve the flexural strength than basalt and glass fiber wrapping. Originality/value SCC, being a high performance concrete, is essential to evaluate the performance under fire conditions. This research work provides the flexural behavior and physical characteristics of SCC subjected to elevated temperature as per ISO rate of heating. In addition attempt has been made to enhance the flexural strength of fire-exposed SCC with wrapping using different fibers. The experimental data will enable the engineers to choose the appropriate material for retrofitting.

This paper compares the flexural performance of reinforced concrete (RC) beams strengthened with textile-reinforced mortar (TRM) and fibre-reinforced polymers (FRP). The investigated parameters included the strengthening material, namely TRM or FRP; the number of TRM/FRP layers; the textile surface condition (coated and uncoated); the textile fibre material (carbon, coated basalt or glass fibres); and the end-anchorage system of the external reinforcement. Thirteen RC beams were fabricated, strengthened and tested in four-point bending. One beam served as control specimen, seven beams strengthened with TRM, and five with FRP. It was mainly found that: (a) TRM was generally inferior to FRP in enhancing the flexural capacity of RC beams, with the effectiveness ratio between the two systems varying from 0.46 to 0.80, depending on the parameters examined, (b) by tripling the number of TRM layers (from one to three), the TRM versus FRP effectiveness ratio was almost doubled, (c) providing coating to the dry textile enhanced the TRM effectiveness and altered the failure mode; (d) different textile materials, having approximately same axial stiffness, resulted in different flexural capacity increases; and (e) providing end-anchorage had a limited effect on the performance of TRM-retrofitted beams. Finally, a simple formula proposed by fib Model Code 2010 for FRP reinforcement was used to predict the mean debonding stress developed in the TRM reinforcement. It was found that this formula is in a good agreement with the average stress calculated based on the experimental results when failure was similar to FRP-strengthened beams.

The use of advanced materials such as Fibre Reinforced Polymer (FRP), for reinforcing (internal reinforcement), prestressing (pre- or post-tensioning) or strengthening (externally bonded, near surface, textile reinforced mortar) of structures, have been gaining increasing interest worldwide. The effectiveness of the FRP techniques have been clearly confirmed by numerous experimental and field applications. This study focuses on the possible use of basalt fibres for FRP rebars or laminates. Basalt is a volcanic igneous rock that because of its high performance in terms of strength, corrosion resistance, temperature range, fire resistance and durability as well as lower potential, cost may effectively replace steel, glass and carbon fibres in many applications. The paper discusses, based on a literature review and some feasibility tests, the possible use of basalt fibres in relation to reinforcing and strengthening of concrete. Herewith, reference is made to (1) basalt fibre composite bars or rods for internal reinforcement, (2) the possibility to use short basalt fibres, and (3) strengthening of concrete members by means of externally bonded reinforcement (EBR), near surface mounted reinforcement (NSM) or textile reinforced mortar reinforcement (TRM). In this paper, the test results in terms of tensile properties of BFRP (basalt FRP) bars and laminates, as well as confinement of plain concrete cylinders with BFRP are presented. This experimental work compares specimens made with BFRP versus GFRP (glass FRP).

This study investigates the Charpy impact strength of unidirectional (UD) carbon fiber, unidirectional (UD) glass fiber, and hybrid composite materials. The results revealed distinct differences in their energy absorption capacities and fracture behaviors. Carbon fiber composites exhibited brittle fractures and low energy absorption, while glass fiber composites displayed significant deformation without a complete fracture, absorbing more energy. The hybrid laminate showed enhanced impact strength, absorbing nearly one-third more energy than the carbon fiber counterpart, and offering a balanced performance improvement through fiber hybridization. Statistical analysis confirmed that the improvement in impact performance among the tested groups was significant. Microscopic analysis of the damaged specimens revealed different damage modes: glass fibers exhibited deformation and mode I delamination, while carbon fibers showed brittle fractures and extensive delamination. Hybrid specimens displayed a combination of damage modes, enhancing their overall impact resistance. These findings demonstrate the potential of hybrid composites for applications requiring balanced mechanical properties, particularly impact resistance. The hybridization method allows for the integration of carbon fibers' high strength with glass fibers' superior impact resistance, enhancing material performance under sudden impact conditions. Future research should focus on optimizing the hybridization process and exploring additional fiber combinations for enhanced material properties.