STRENGTHENING OF RC BEAMS USING NEAR SURFACE EMBEDDED-FRCM

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Usama Ebead ◽  
Hossameldin El-Sherif
Keyword(s):  
Experimental Evidence ◽  
Masonry Structures ◽  
Rc Beams ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Reinforced Beams ◽  
Concrete Layer ◽  
Test Parameters ◽  
Externally Bonded ◽  
Strengthening Technique

Fibre reinforced cementitious matrix (FRCM) systems are mostly externally bonded (EB) for the strengthening of reinforced concrete (RC) and masonry structures. In this paper, the relatively new concept of near-surface embedded (NSE) FRCM, has been introduced for the flexural strengthening of beams. The process of the application of NSE-FRCM strengthening technique involves the removal of the concrete layer at beam soffit, being the most deteriorated in actual practices. Experimental evidence of the flexural strengthening efficacy of this technique is provided here. Eight RC beams were prepared and tested under four-point loading with the consideration of two test parameters: (a) FRCM material (polyparaphenylene benzobisoxazole (PBO)/carbon/ glass); and (b) the reinforcement ratio (0.5% representing flexure-deficient beams and 1.28% representing typical under-reinforced beams). The strengthening led to gains in ultimate loads that ranged between 31.4% and 84.3%.

Comparative study on the flexural strengthening of RC beams using EB CFRP sheets, NSM CFRP bars, P-SWRs, and their combinations

2020 ◽  
pp. 136943322097172
Author(s):  
Yihua Zeng ◽  
Xinghua Li ◽  
Amira Hamdy Ali Ahmed ◽  
Gang Wu
Keyword(s):  
Steel Wire ◽  
Experimental Investigations ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Wire Ropes ◽  
Cfrp Sheets ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Strengthening Technique ◽  
Space Requirements

The externally bonded (EB) carbon fiber reinforced polymer (CFRP), near-surface-mounted (NSM) CFRP and the prestressed steel wire ropes (P-SWRs) has been proven to be feasible and reliable flexural strengthening methods for concrete structures. However, debonding issues in EB CFRP sheets (or NSM CFRP bars) and space requirements for edge and spacing clearance of NSM CFRP bars (or P-SWRs) has limited the application of these three strengthening techniques. Therefore, the combinations of these methods need to be investigated and clarified. In this paper, experimental investigations on the flexural performances of seven concrete beams are presented, in which three of the beams were separately strengthened with EB CFRP sheets, NSM CFRP bars, and P-SWRs, respectively, and three of the beams were combinedly strengthened with two of the three techniques. Test results demonstrated that the flexural performances of beams strengthened with the combination with EB CFRP sheets, NSM CFRP bars, and P-SWRs are between the flexural performances of the beams strengthened with the corresponding individual strengthening techniques. It is found that the P-SWRs is favorable for combinations. In case the P-SWRs was combined with EB CFRP sheets or NSM CFRP bars for strengthening, the cracking load was increased to more than 230% and the maximum ultimate load-bearing capacity was increased to 150% when compared with the control beam. The debonding which occurred more or less in the beams strengthened with EB CFRP sheets or NSM CFRP bars or their combination was successfully eliminated by using the combination strengthening technique with P-SWRs. Also, the combination of P-SWRs with EB CFRP sheets or NSM CFRP bars is also favorable to improve the ductility of strengthened beams.

Comparison of Various Techniques for Flexural Strengthening of Thin Concrete Members Using Continuous Carbon Fibers

2015 ◽  
Vol 1120-1121 ◽  
pp. 1458-1462
Author(s):  
Andrej Ivanič ◽  
Samo Lubej
Keyword(s):  
Carbon Fibers ◽  
Flexural Stress ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Flexural Performance ◽  
Concrete Members ◽  
Modes Of Failure ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Strengthening Technique

This paper deals with flexural performance of thin concrete members reinforced with continuous carbon fibers in the form of filament yarns. The laboratory specimens were tested under static loading conditions to investigate the effects of three different strengthening techniques on flexural stress, mid-span deflection and modes of failure. The specimens were strengthened in flexure using carbon fiber yarns as near-surface mounted, externally bonded and placed in the geometric center of the specimen, respectively. Based on this investigation, the advantages and shortcomings of individually strengthening technique can be drawn.

scholarly journals Evaluation of Effective Polymer Fiber Length on Energy Absorption Capacity of Reinforced Beams by EBR and NSM Methods

2021 ◽  
Vol 30 (3) ◽  
Author(s):  
Komeyl Karimi-Moridani
Keyword(s):  
Energy Absorption ◽  
Crack Nucleation ◽  
Absorption Capacity ◽  
Rc Beams ◽  
Energy Absorption Capacity ◽  
Near Surface ◽  
Cfrp Sheets ◽  
Reinforced Beams ◽  
Cfrp Sheet ◽  
Externally Bonded

This study presents a comparison of two methods used for retrofitting Reinforced Concrete (RC) beams, namely, the Externally Bonded Reinforcement (EBR) and the Near-Surface Mounting (NSM) methods. A parametric analysis was carried out using variables such as the retrofitted, the retrofitting method (EBR and NSM), and the thickness of the Carbon Fiber-Reinforced Polymer (CFRP) sheets. To achieve this goal, the finite element method and ABAQUS software were employed. An un-retrofitted beam was also simulated as the control specimen for comparison. Beam responses were compared through load–displacement and energy absorption capacity diagrams. Results show that the higher energy absorption capacity in all CFRP-retrofitted RC beams, which was 1.69–5.54 times higher than in un-retrofitted beams. In the case where half of the beam was reinforced using CFRP sheets, the entire beam assembly and the CFRP sheet contributed to load-bearing, thus delaying crack nucleation in the beam and increasing its energy absorption capacity. As a result, the energy absorption capacity of the beam, in this case, was less than that obtained in the previous one where half the span of the beam was retrofitted.

scholarly journals Flexural strengthening of RC beams by using a near surface mounted T-section profiles

2014 ◽  
Vol 13 (3) ◽  
pp. 071-078
Author(s):  
Szymon Chołostiakow ◽  
Renata Kotynia
Keyword(s):  
Reference Beam ◽  
Concrete Surface ◽  
Experimental Program ◽  
Rc Beams ◽  
Test Results ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Existing Structures ◽  
Near Surface Mounted ◽  
Strengthening Technique

The paper presents test results of an experimental program of four full-scale RC beams, strengthened in flexure with T-section carbon fiber reinforced polymer (CFRP) profiles and two reference beams subjected to a six point bending. The novel shape of CFRP profile combines both the near surface mounted (NSM) and externally bonded (EB) strengthening systems. The application of the CFRP profiles consisted of gluing both the web and the flange of the profile to the concrete surface. RC beams made of the same concrete class were differed by the internal steel reinforcement ratio and in a number of applied profiles. Efficiency of this new strengthening product was determined by comparison of the strengthened and non-strengthened RC beams. An increase of the CFRP-concrete bond area and high stiffness of the T-section profiles significantly improved the strengthening ratio (up to 130% of the reference beam) and reduced the maximum mid-span deflection (ranged of 70-80%) of the non–strengthened beams. The CFRP strain utilisation equal to 67% of the tensile strain corresponded to the maximum CFRP strains equal to 0,73%. The promising test results exhibit this system as a very attractive proposal of new strengthening technique used for field applications of the  existing structures.

scholarly journals Effects of RC beams reinforcement using near surface mounted reinforced FRP composites

2010 ◽  
Vol 8 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Slobodan Rankovic ◽  
Radomir Folic ◽  
Marina Mijalkovic
Keyword(s):  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Near Surface ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Reinforced Beams ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Basic Characteristics ◽  
Frp Bars

This paper analyzes application of modern reinforcement methods for reinforced concrete (RC) beams using fiber-reinforced polymer (FRP) materials. Basic characteristics of FRP materials and the method of mounting the FRP bars within concrete, that is, near the surface of the beams (NSM method) are presented. The properties of this method and its advantages in comparison to externally bonded reinforcement laminate method (EBR) have been analyzed. The results of measured deflections and width of the cracks of the beams reinforced by FRP bars, depending on the load are presented and discussed, in comparison to the results obtained from the non-reinforced beams. The experimental research was published at the Faculty of Civil Engineering and Architecture of Nis in 2009.

scholarly journals FLEXURAL BEHAVIOR OF RC BEAMS STRENGTHNED WITH CFRP SHEETS USING DIFFERENT STRENGTHENING TECHNIQUES

2019 ◽  
Vol 16 (1) ◽  
pp. 35
Author(s):  
Sherif El Gamal ◽  
Ali Al-Nuaimi ◽  
Abdullah Al-Saidy ◽  
Khalid Al-Shanfari
Keyword(s):  
Reference Beam ◽  
Flexural Behavior ◽  
Hybrid Technique ◽  
Rc Beams ◽  
Ultimate Capacity ◽  
Near Surface ◽  
Cfrp Sheets ◽  
Four Point Bending ◽  
Externally Bonded ◽  
Strengthening Technique

Due to the advantages of Fiber Reinforced Polymer (FRP) materials, they have been utilized to strengthen several reinforced concrete (RC) elements such as slabs, beams and columns. In this paper, five RC beams (200 mm width, 300 mm height, and 2750 mm length) were constructed. Four of these beams were strengthened with CFRP sheets whereas the last beam was used as a reference. Test parameters include the amount of FRP and the strengthening technique. Three strengthening techniques were used including the externally bonded technique (EB), the near surface mounted (NSM) technique using folded CFRP sheets inserted in near surface grooves, and a hybrid technique. All beams were tested under four point bending setup until failure. The control beam failed by the yielding of the tension steel followed by concrete crushing. The strengthened beams failed by steel yielding followed by either rupture or debonding of CFRP sheets at higher loads compared to the reference one. The stiffness after steel yielding and the ultimate capacity increased as the amount of CFRP increased. The strengthening technique affected the ultimate capacity of the strengthened beams. The NSM beam showed the lowest increase in the ultimate capacity (25.2%) whereas the hybrid beam showed the best performance with the highest increase in the ultimate capacity (58%) compared to the reference beam.

EFFECTIVENESS OF FRCM SYSTEM IN STRENGTHENING RC BEAMS IN SHEAR USING HYBRID NSE/EB TECHNIQUE

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Usama Ebead ◽  
Tadesse Wakjira
Keyword(s):  
Ultimate Load ◽  
Shear Capacity ◽  
Reference Specimen ◽  
Rc Beams ◽  
Test Results ◽  
Promising Alternative ◽  
Near Surface ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Fabric Reinforced Cementitious Matrix

This paper presents an experimental study on the efficacy of a recently introduced hybrid “near surface embedded/ externally bonded” NSE/EB fabric reinforced cementitious matrix (FRCM). Seven medium scale RC beams, deficient in shear, were constructed and tested under three-point loading. Six beams were strengthened using hybrid NSE/EB-FRCM technique and one beam was left un-strengthened as a reference. Two main test variables were considered; viz., strengthening configuration: full versus intermittent strengthening configuration and FRCM type: glass FRCM versus polyparaphenylene benzobisoxazole (PBO). The test results revealed that the hybrid NSE/EB-FRCM strengthening technique is effective in enhancing the shear capacity of the strengthened beams. The strengthened specimens showed an average of 67% higher shear capacity relative to the reference specimen. With regard to the FRCM type, G-FRCM strengthened specimens showed an average of 73% enhancement in the shear capacity, which was 12% higher than the value for PBO-FRCM counterpart. Moreover, the strengthened beams showed higher deflection at the ultimate load than that of the reference specimen. Furthermore, the hybrid NSE/EB-FRCM technique has shown to be a promising alternative to the conventionally used externally bonded FRCM system with the potential to reduce the debonding of FRCM from the concrete substrate.

scholarly journals Strengthening of RC Beams Using Externally Bonded Reinforcement Combined with Near-Surface Mounted Technique

Polymers ◽  
2016 ◽  
Vol 8 (7) ◽  
pp. 261 ◽  
Author(s):  
Kh Darain ◽  
Mohd Jumaat ◽  
Ahmad Shukri ◽  
M. Obaydullah ◽  
Md. Huda ◽  
...  
Keyword(s):  
Rc Beams ◽  
Near Surface ◽  
Externally Bonded ◽  
Near Surface Mounted

scholarly journals Flexural strengthening of RC beams with NSM CFRP laminates

2020 ◽  
Vol 323 ◽  
pp. 01010
Author(s):  
Damian Szczech ◽  
Łukasz Krawczyk ◽  
Renata Kotynia
Keyword(s):  
Reference Beam ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Carbon Fibre Reinforced Polymer ◽  
Bottom Side ◽  
Cracking Pattern

The paper presents test results of reinforced concrete beams flexurally strengthened with Carbon Fibre Reinforced Polymer (CFRP) laminates using the Near Surface Mounted (NSM) technique. RC beams with a cross section of 200 x 400 mm were tested in four-point bending. Two RC beams were strengthened with one NSM CFRP laminate installed into the concrete cover on the bottom side of the beam. One of the beams was strengthened under the self-weight (B10.1) and the second one under initial preloading equal to 83% of the ultimate load of the reference beam (B10.1o). Failure mechanisms, cracking pattern and flexural behaviour of the beams are described in the paper. All the strengthened beams failed by rupture of the CFRP laminates followed by the internal steel reinforcement yielding. High strengthening efficiency of the NSM strengthening was confirmed by 109% and 130% when compared with the non-strengthened beam, respectively for beams B10.1 and B10.1o.

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