Shear strengthening of RC beams using near-surface mounted carbon fibre-reinforced polymers

Rjoub, Yousef S. Al; Ashteyat, Ahmed M.; Obaidat, Yasmeen Taleb; Bani-Youniss, Saleh

doi:10.1080/13287982.2019.1565617

Cited by 21 publications

(20 citation statements)

References 15 publications

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“…Due to the limited depth of RC beams, the length of CFRP reinforcements was equal to the beam depth for the rectangular cross section beams in the most experimental tests [17,31,88]. However, using NSM strips with the length of 1/2D or 2/3D (D is the depth of beam) caused a noticeable improvement in the ultimate load of beam compared to using the length of NSM strips covering the full depth of beam [89]. e ultimate load of beams strengthened with full-length NSM strip was capable of sustaining a 144% higher load than that having length of NSM strips 1/2D.…”

Section: Length Of Nsm Reinforcementmentioning

confidence: 99%

Section: Concrete Cover Depthmentioning

confidence: 99%

“…e effect of the side cover depth was investigated by [89]. Generally, it was found that, by increasing side concrete cover depth, the side concrete cover separation can be delayed or even prevented [89,94,95]. However, increasing the side cover could have a negative effect on the flexural response of beams since it may limit the space provided to position the longitudinal reinforcement.…”

Section: Concrete Cover Depthmentioning

confidence: 99%

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Review on NSM CFRP Strengthened RC Concrete Beams in Shear

Kadhim

Altaee

Adheem

et al. 2021

Advances in Civil Engineering

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The use of NSM FRP strengthening of concrete structures has become an attractive option to retrofit the existing structures against shear and flexure. This paper reviews only the utilization of NSM for shear in previous review articles. A database of tests of NSM strengthened beams in shear is presented to evaluate the existing design formulations of calculating the NSM contribution in shear. These formulations were in agreement with the experimental results in the database. Further research topics are also identified such as the shape of NSM FRP bars, combined effects of existing steel stirrups, and NSM FRP reinforcement and analytical formulations.

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Section: Length Of Nsm Reinforcementmentioning

confidence: 99%

Section: Concrete Cover Depthmentioning

confidence: 99%

Section: Concrete Cover Depthmentioning

confidence: 99%

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Review on NSM CFRP Strengthened RC Concrete Beams in Shear

Kadhim

Altaee

Adheem

et al. 2021

Advances in Civil Engineering

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“…Many studies used the NSM technique in strengthening RC beams using CFRP rods [14]- [16], CFRP laminates and strips [17], [18], Aluminum alloy bars [19], and steel bars [20]. Compared to external bonding strengthening technique, the NSM system has merits, including:…”

Section: Introductionmentioning

confidence: 99%

Strengthening the Self Compacting Reinforced Concrete Dapped Ends with Near Surface Mounted (NSM) Steel Bar Technique

Shakir

Alliwe

2021

Int. J. Adv. Sci. Eng. Inf. Technol.

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An experimental study has been conducted to explore the response of reinforced self-compacting concrete dapped ends retrofitted with NSM steel bars. Eleven specimens are tested with two shear slenderness ratio values (a/d), namely (1.0 and 1.5). Deficiencies in reinforcement in the nib and hanger zone are considered. The response is studied in terms of loading history, cracking and failure load, failure mode, cracking pattern, toughness, stiffness, and ductility. It is observed that retrofitting the nib region with horizontal bars improved the capacity by 29% and 20% for the two shears span/depth (a/d) values, respectively. The maximum enhancement in the capacity for upgraded hanger regions with a/d= 1 is about 21%. Regarding toughness, this research indicated that for reduced nib steel specimens with a/d=1.0 and 1.5, a reduction by 17% and 27%, respectively, were obtained. Whereas reducing the hanger steel by 30% led to a drop by 29%. Strengthening of deficient nib reinforced specimens with a/d =1.0 and 1.5 led to an improvement in toughness by 43% and 62%, respectively. For specimens with deficient hanger steel (a/d=1.0), the strengthening led to toughness enhancement by 87%. Strengthening of deficiently reinforced nib end with the two a/d values resulted in improving stiffness by 18% and 24%, whereas when strengthening the hanger zone, an enhancement of 9% is obtained. For ductility, it is concluded that the prediction of ductility ratio using the displacement ratio method is more efficient than the toughness ratio method because it is considered the premature failure cases. Also, it is obtained that increasing the a/d value resulted in reducing the ductility ratio.

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“…Near surface mounted (NSM) technique had been also introduced as a more efficient alternative in FRP strengthening of RC beams [11,12,13,14]. In this technique, a pre-cut groove using saw is made on the tension surface/face of the beam.…”

Section: Introductionmentioning

confidence: 99%

Shear Strengthening of R.C Beams with FRP Using (NSM) Technique

Abdel-Kareem

Debaiky

Makhlouf

et al. 2019

AIR

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This paper presents the experimental results of investigations the shear behavior of strengthened reinforced concrete beams by using glass fiber reinforced polymers (GFRP) rods. The strengthening system used GFRP rods were done by Near Surface Mounted technique (NSM), NSM technique contains a groove on the outside surface of the concrete member to adjust the depth to be less than the cover of the member. After cleaning, the epoxy paste was used to fill half of the groove's depth. The particular FRP element is then mounted in the groove. Finally, the groove is filled with epoxy and the too much epoxy is leveled with the outside surface of the concrete. This method enables the fiber reinforcement polymer FRP materials is covered completely by epoxy. The main objective of this research is to study the effect of NSM technique on shear resistance for RC beam. The parameters are considered in this study are effect of the material type used for strengthening (inner steel stirrups and external glass fiber stirrups), effect of FRP rods inclination on strengthened beams, shape with different end anchorage of FRP (strips and rods), and the effect of number of the used FRP rods. This paper involved 13 experimental investigations of half-scale R.C beams. The experimental program included two specimens strengthened with inner steel stirrups, eight specimens strengthened with stirrups of Glass Fiber Reinforced Polymer GFRP rods with the shape of different end anchorage and angle, and two specimens strengthened with externally bonded GFRP strips. The remaining un-strengthened specimen was assigned as a control one for comparison. The test results included ultimate capacity load, deflection, cracking, and mode of failure. All beams strengthened with GFRP rods showed an increase in the capacity ranging between 14% to 85% comparing to the reference beam, and beams strengthened with GFRP strips showed an increase in the capacity ranging between 7% to 22% comparing to the reference beam.

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Shear strengthening of RC beams using near-surface mounted carbon fibre-reinforced polymers

Cited by 21 publications

References 15 publications

Review on NSM CFRP Strengthened RC Concrete Beams in Shear

Review on NSM CFRP Strengthened RC Concrete Beams in Shear

Strengthening the Self Compacting Reinforced Concrete Dapped Ends with Near Surface Mounted (NSM) Steel Bar Technique

Shear Strengthening of R.C Beams with FRP Using (NSM) Technique

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