STUDY ON BEHAVIOR OF FRP SHEET DEBONDING AS FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAM (original) (raw)
Related papers
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.
DEBONDING BEHAVIOR OF GFRP SHEET REINFORCED CONCRETE (BM-136
The fiber reinforced polymer (FRP) has been applied to many purposes for civil engineering structures not only for new structures but also for strengthening of the deteriorated structures. Many researches have been done as an effort to apply the FRP materials for strengthening, particularly due to an increase on load requirement, a change of use or due to a degradation problem or some design/construction defects. However, widely application is still questionable until a fundamental understanding of bonding behavior is clearly available. This paper is mainly focused on the study of the debonding behavior of FRP sheet patched on the tensile fiber of concrete beam. A series of GFRP sheet reinforced concrete beams with various length and width of GFRP sheet was prepared. For the purpose of purely investigation on the GFRP sheet as reinforcement, all beams were not reinforced by steel bars. The beams were loaded under four points bending test. Results indicated that debonding of GFRP sheet started on the flexural cracks and it was propagated to the sheet end.
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.
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.
Enhancement of the Tensile Strength of Reinforced Concrete Beams Using GFRP
Use of externally bonded Glass Fiber Reinforced Polymer (GFRP) sheets/strips/plates is a modern and convenient way for strengthening of RC beams. GFRP can be classified as a type of composite material that is increasingly used in the construction industry in recent years. Due to their light weight, high tensile strength, corrosion resistance and easy to implementation makes these material preferred solutions for strengthening method of reinforced concrete structural elements. This paper presents the experimental results on the confining effects of GFRP wraps in the tension-zone of reinforced concrete RC beams. A total of 16 beam specimens were used in this study. The beam dimensions were 150 mm width, 150 depths, and 620 span lengths center to center with total length 700 mm. The test parameters include number of layers and width of GFRP. The GFRP laminates were applied 580 mm in length. The specimens were tested in four points bending to failure. This paper provides new information on the degree of GFRP enhancement for reinforced concrete members and the effect of the GFRP wrapping width and layers, and increase in capacity to prevent cracks in tension zone with and without GFRP wrapping. The results of tests have been evaluated and compared with international codes. Consequently it has been noted that the GFRP materials enhance both strengthening and ductility of reinforced concrete beam sections. When trying to utilize fiber polymer sheets, either made of carbon CFRP or steel SFRP, as external shear reinforcement attached on RC beams, their potential of high tensile strength is prevented by the GFRP sheets.
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)
The Role of the Bond on the Structural Behaviour of Flexural FRP Reinforced Concrete Members
2005
The paper focuses on the bond between fibre-reinforced polymer (FRP) reinforcements and concrete including its modelling (local bond-slip law) and influence on the structural behaviour of FRP reinforced concrete members. The analysis, both theoretical and experimental, refers to flexural concrete beams upgraded by externally bonded FRP sheets, considering different bonding systems such as the commonly used resin-FRP system and novel bonding technologies (near surface mounted system, cementitious-FRP system). The structural behaviour of strengthened beams is analyzed by means of a non linear model derived from a cracking analysis based on slip and bond stress. By using some bond-slip models, the performances of beams under service conditions (cracking, deformability) are evaluated varying parameters governing the FRP-to-concrete bond behaviour. Results of the analysis furnish useful information to find interface bonding systems which can offer suitable bond characteristics to optimize the performances of FRP reinforced concrete members.
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.
The Bond Strength of Glass Fiber Reinforced Polymer (GFRP) Reinforcement with Monolith Concrete
IJASEIT, 2018
One of the considerations in selecting Glass Fiber Reinforced Polymer (GFRP) as a substitute for conventional reinforcement is its ability against corrosion makes it suitable for structures directly related to land, water, and corrosive areas. Regarding strength, GFRP which has high yield strength is very suitable as a reinforcement to hold the shear force. Similarly, as with steel bar, GFRP reinforcement is used as a composite material of reinforced concrete; therefore, it is worth to know the grade of the bond strength. The bond strength is one of the crucial factors to have a good interaction between GFRP and concrete in holding workloads on structures so that the study is conducted to get the grade of the bond strength of GFRP reinforcement with monolith concrete cast. The experiment is using the pullout test with a cube specimens, sized 250 mm × 250 mm × 250 mm and GFRP bar sized 25 mm diameters. Bond strength of GFRP reinforcement will then be close compared to the bond strength of BJTS40 deform rebar sized 25 mm diameters. The concrete used in this study has about f'c 100 MPa. The test results indicate the grade of bond strength of GFRP reinforcement with concrete reaches 6.54 MPa and the bond strength of steel bar with concrete reaches 8.22 MPa. The degree of bond strength of GFRP reinforcement is smaller 79.56% than the bond strength of the steel reinforcement. What the failure happened on all test objects is the mode of splitting failure.