Effects of Externally Bonded GFRP Sheet on Flexural Strengthening under Post-Yielded Reinforced Concrete Beams (original) (raw)
Related papers
STUDY ON BEHAVIOR OF FRP SHEET DEBONDING AS FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAM
Strengthening of structures with Glass Fiber Reinforced Polymer (GFRP) sheets is an effective method to increase the capacity of the structures. This GFRP material has a tensile strength of up to 3240 Mpa so that when used in a concrete structure it can play an effective role in enhancing the tensile strength of the structure elements. However, the release of the GFRP sheet from the concrete surface (debonding) is the cause of the non-optimal ability of the strengthened beam. This paper is focused on the study of the debonding behavior of GFRP sheet patched on the tensile section of a concrete beam. The specimen consisted of three control beams and nine strengthened beams with various bond area of GFRP sheet. The observed data were the maximum load, deflection, concrete strain and GFRP strain. The results indicated that the flexural capacity of the strengthened beam increased up to 10.85 % compared to the normal beam. The bonding length of the GFRP sheets has no significant effect on the load capacity. Moreover, all the strengthened beams failed by the debonding of the bonded sheet, which was initiated by local debonding on the critical bonding stress location.
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.
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.
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.
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.
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)
2012
In this study, experimental investigations were conducted regarding flexural strengthening of reinforced concrete (RC) beams using high-toughness polymer cement mortar (HTPCM) and continuous fiber reinforcements. Our results showed that using the HTPCM as section recovering and thickening materials is effective in improving flexural strengthening effect of continuous fiber sheets/plates and rods on RC beams, because diagonal tensile cracking in tension-side covering concrete and bond-splitting failure of thickened part are prevented by the HTPCM. Furthermore, it was also shown that the flexural strengthening effect does not remarkably decline by upward execution, if plastering thickness of HTPCM of one time is adjusted to 6 mm or less.
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.
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...