Enhancement of the Tensile Strength of Reinforced Concrete Beams Using GFRP (original) (raw)
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FLEXURAL BEHAVIOUR OF REINFORCED CEMENT CONCRETE BEAM WRAPPED WITH GFRP SHEET
Existing concrete structures may, for a variety of reasons, be found to perform unsatisfactorily. This could manifest itself by poor performance under service loading, in the form of excessive deflections and cracking, or there could be inadequate ultimate strength. Additionally, revisions in structural design and loading codes may render many structures previously thought to be satisfactory, noncompliant with current provisions. In the present economic climate, rehabilitation of damaged concrete structures to meet the more stringent limits on serviceability and ultimate strength of the current codes, and strengthening of existing concrete structures to carry higher permissible loads, seem to be a more attractive alternative to demolishing and rebuilding. This paper investigates the Flexural behavior of R.C.C. beam wrapped with GFRP Glass Fiber Reinforced Polymer) sheet. A total 8 beams, with (150×150) mm rectangular cross section and of span 700 mm were casted and tested. Three main variables namely, strength, ductility and damage level of R.C.C. under reinforced beam and R.C.C. beam weak in flexure were investigated. In first set of four R.C.C. under reinforced beams two were strengthened with GFRP sheet in single layer from tension face which is parallel to beam axis subjected to static loading tested until failure; the remaining two beams were used as a control specimen. In second set of four beams weak in flexure two were strengthened with GFRP sheet tested until failure; the remaining two were used as a control specimen. Comparison has been made between results of two sets.
2020
The application of GFRP sheets as the strengthening material in the damaged reinforced concrete structures have found increasingly wide. Due to yielding of the longitudinal rebars, the load bearing capacity decreases. This study represents the experimental work of the strengthening reinforced concrete beams using externally glass fiber reinforced polymer (GFRP). Six RC beams with 3.3 m length and with dimensions of 150.0 mm x 200.0 mm were tested. The specimens consisted of three normal beams and three strengthened beams. One layer of the GFRP sheet was bonded on the bottom face of the strengthened beam. The results indicated that the flexural capacity of the strengthened beam enhanced up to 17.7% compared to the normal beam. The strengthened beams failed by intermediate flexural crack induced interfacial debonding (IC-debonding). The ICdebonding causes premature failure of the strengthened beam.
Performance Analysis of Reinforced Concrete Beam with GFRP Using Finite Element Method
International Journal of Application on Sciences, Technology and Engineering
Structural strengthening is required when structures suffer from minor damage or strength degradation. Structural strength degradation can be caused by incorrect initial design, structural age, environmental factors, or changes of building functions. One of the strengthening solutions is Glass Fiber Reinforced Рolymer (GFRР) due to its easy application and good mechanical properties such as. This research discussed the effect of externally bonded GFRР sheets on the flexural capacity of reinforced concrete beams. The concrete specimens had dimensions of 150×250×3300 mm and were simply supported beams tested using two point symmetrical loading. Flexural strengthening was done by applying GFRР sheets to the bottom side of the beams (bottom wrapping). Flexural capacity analysis was done using finite element method with the help of MIDAS FEA program and shows 27,915-70,521% flexural capacity increasement for each GFRP layer addition for bottom wrapping models. Finite element analysis res...
Reinforced Concrete (RC) structures are designed for a particular load carrying capacity and they are expected to function safely during their service life. Several strengthening methods are being adopted to extend the service life of damaged structures. Plate bonding technique using Fibre Reinforced Polymer (FRP) shows a better choice of strengthening method of RC structural elements. Glass Fibre Reinforced Polymer (GFRP) Sheet offers a viable alternative in repair and strengthening of RC structures. The objective of this investigation is to study the effectiveness of the retrofitting beams by fixing GFRP sheet at the tension zone (soffit of beam) for increasing the flexural strength of RC beams. Two point bending flexural tests were conducted up to failure on reinforced concrete beams retrofitted and control beams.
The solution of using glass fiber reinforced polymer (GFRP) bars, as reinforcement in concrete structures to overcome the problems created by steel reinforcement, is now widely accepted because of both its low cost and good results shown by large investigation efforts. In this paper twelve tests had been conducted on reinforced concrete column specimens of (120 x 120 x 1000 mm effective dimensions) equally enlarged from both ends for the purpose of applying eccentric load, three specimens were made of high strength concrete , reinforced with traditional deformed steel bars and stirrups to be considered as references, while the remaining nine specimens were of high strength concrete with 0, 0.5, 1.0% steel fiber, reinforced longitudinally with GFRP bars and wrapped with carbon fiber reinforced polymer (CFRP) textile replacing the steel stirrups .In addition to the similarity in behavior under load and in the failure patterns of the specimens reinforced with GFRP bars and the specimens reinforced with traditional steel, the results show that Steel reinforced columns has 13% higher ultimate load than corresponding GFRP reinforced columns, also an approximate linear increase in the first crack and failure load with the presence of steel fiber in concrete in range from 20% to 42% for 1% fiber content and in range of 21% to 26 % for the first crack and ultimate load respectively . The ductility of the specimen reinforced with GFRP bars is 90% higher than that of steel reinforced specimens of 𝝆=2.18% and 10% more for those of 𝝆=5.58%.
EXPERIMENTAL INVESTIGATION OF CONCRETE BEAMS REINFORCED WITH GFRP BARS
Glass fiber reinforced polymers (GFRP) reinforcement bars has a lower stiffness than steel reinforcement, which should be accounted for the ultimate and serviceability conditions, including the impact on member deflection and crack widths. This paper presents an experimental study of the flexural behavior of concrete beams reinforced with locally produced glass fiber reinforced polymers (GFRP) bars. The bars are locally produced by double parts die mold using local resources raw materials. A total of seven beams measuring 120 mm wide x 300 mm deep x 2800 mm long were caste and tested up to failure under four-point bending. The main parameters were reinforcement material type (GFRP and steel), concrete compressive strength and reinforcement ratio (μb, 1.7μb and 2.7μb). The mid-span deflection, crack width and GFRP reinforcement strains of the tested beams were recorded and compared. The test results revealed that the crack widths and mid-span deflection were significantly decreased by increasing the reinforcement ratio. The ultimate load increased by 47% and 97% as the reinforcement ration increased from μb to 2.7μb. Specimens reinforced by 2.7μb demonstrated an amount of ductility provided by the concrete. The recorded strain of GFRP reinforcement reached to 90% of the ultimate strains.
Study on Effect of Reinforced Concrete Beam with Bonded Glass Fiber Reinforced Polymer Sheets
The application of Glass Fiber-reinforced polymers (GFRP) to existing Reinforced Concrete (RC) structural elements as external reinforcement has become popular and frequently applied in recent years. An analytical and experimental study has been carried out to investigate the behavior of concrete beams bonded with strengthened Glass Fiber-Reinforced Polymer (GFRP) sheets on all sides with different thickness under loading. Several investigators carried out experimental and or theoretical investigations on concrete beams and columns retrofitted with glass Fiber-reinforced polymer composites in order to study their effectiveness. The experiment has been carried out for the comparison and the study of effect of GFRP. Masonry structures also benefit with FRP reinforcement. Their use as original reinforcement and for strengthening structure is being specified more and more by structural engineers in the construction industry. FRPs using glass fibers are the predominant reinforcing fiber in all industries. It has high electrical insulating properties, good heat resistance, and has the lowest cost.
2016
Reinforced Concrete (RC) structures are designed for a particular load carrying capacity and they are expected to function safely during their service life. Several strengthening methods are being adopted to extend the service life of damaged structures. Plate bonding technique using Fibre Reinforced Polymer (FRP) shows a better choice of strengthening method of RC structural elements. Glass Fibre Reinforced Polymer (GFRP) Sheet offers a viable alternative in repair and strengthening of RC structures. The objective of this investigation is to study the effectiveness of the retrofitting beams by fixing GFRP sheet at the tension zone (soffit of beam) for increasing the flexural strength of RC beams. Two point bending flexural tests were conducted up to failure on reinforced concrete beams retrofitted and control beams.
BONDING STRESS DISTRIBUTION OF GFRP FOR FLEXURAL STRENGTHENING ATTACHED OF RC BEAMS
Fiber-Reinforced Plastic (FRP) reinforcement has been utilized for concrete structures expecting its high durability to corrosion and insulation property. The application of FRP in various forms such as grid, rod and sheet. GFRP sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. This study using consisted of five beams categorized into two groups. The test span of all beams were 3300 mm. The cross section was 150 x 200 mm. The beam of the first group (BN) were tested without strengthening GFRP, totaling two beams. The beams of the second group (BF) with strengthened (before loading) with GFRP sheet on the bottom, totaling three beams. The Samples were tested simply supported and were subjected to two point load symmetrically placed at equal distance (150 mm) from the centerline of the beam. This study result, shows the advantage of using GFRP sheets in strengthening or upgrading RC beams. value of Interface shear stress (t) 8,25 Mpa and relative moment of resistance (Ms/Mp) 1,50. Failure is a general loss of GFRP beams of concrete (debonding)