Rehabilitation of defected RC stepped beams using CFRP

Afefy, Hamdy M.; Mahmoud, Mohamed H.; Fawzy, Tarek M.

doi:10.1016/j.engstruct.2012.11.013

Cited by 12 publications

(5 citation statements)

References 15 publications

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“…It was deduced that the application of the U-anchor system to the externally bonded FRP laminates increased the ultimate capacity of a dapped-end and ensured fiber rupture instead of deboning of the FRP sheets. Afefy et al [10] conducted experimental and analytical study to investigate the efficiency of external bonding (EB) technique using CFRP strips and sheets to retire the full capacity of deficiently reinforced stepped beams.…”

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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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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“…Stepped beam under vibration load face complex excitation that may be the cause of failure. It is very essential to develop a reliable model to study stepped beam under vibration [7][8][9][10][11]. Structural defects such as crack are very common in nano elements.…”

Section: Introductionmentioning

confidence: 99%

The effect of rotatory inertia on natural frequency of cracked and stepped nanobeam

Hossain

Lellep

2020

Eng. Res. Express

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Nanobeams are extensively used in the arena of modern science and technology. The dynamic model of nanobeam with steps and cracks is formed by the combination of classical beam theory and nonlocal theory of elasticity. Homotopy perturbation method is employed to solve the governing equations for two steps nanobeam. The results of this approximation method are compared with the results of exact solution technique. Our vital concern is to analyse the effect of rotatory inertia on the dynamic behaviour of nanobeam. The effect of crack severity, crack and step position, step height ratio, axial load on the vibration of nanobeam are also studied. The results show that the effect of rotatory inertia is very significant in the nanobeam and its influence increases with the increase of mode of frequency. RECEIVED

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“…Thus, most RC beams with a T-shaped cross-section are shear strengthened using EB-FRP sheets (jackets or strips) on the three sides of the web of the beam (U-shaped retrofitting). A significant deficiency of this technique is the premature failure of the strengthened member due to the debonding of the EB-FRP at the adhesive composite and concrete interface [13][14][15][16][17][18][19][20].Several experimental studies have demonstrated the effectiveness of the use of EB-FRP sheets in strengthening procedures of shear-deficient RC members. Chaallal et al [21] proposed one of the first models for predicting the shear contribution of the EB-FRP based on the assumption that the composite fibers contribute to the shear capacity similar to internal transverse reinforcement.…”

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confidence: 99%

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confidence: 99%

U-Jacketing Applications of Fiber-Reinforced Polymers in Reinforced Concrete T-Beams against Shear—Tests and Design

Chalioris

Zapris

Karayannis

2020

Fibers

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The application of externally bonded fiber-reinforced polymer (EB-FRP) as shear transverse reinforcement applied in vulnerable reinforced concrete (RC) beams has been proved to be a promising strengthening technique. However, past studies revealed that the effectiveness of this method depends on how well the reinforcement is bonded to the concrete surface. Thus, although the application of EB-FRP wrapping around the perimeter of rectangular cross-sections leads to outstanding results, U-jacketing in shear-critical T-beams seems to undergo premature debonding failures resulting in significant reductions of the predictable strength. In this work, five shear-critical RC beams with T-shaped cross-section were constructed, strengthened and tested in four-point bending. Epoxy bonded carbon FRP (C-FRP) sheets were applied on the three sides and along the entire length of the shear-strengthened T-beams as external transverse reinforcement. Furthermore, the potential enhancement of the C-FRP sheets anchorage using bolted steel laminates has been examined. Test results indicated that although the C-FRP strengthened beams exhibited increased shear capacity, the brittle failure mode was not prevented due to the debonding of the FRP from the concrete surface. Nevertheless, the applied mechanical anchor of the C-FRP sheets delayed the debonding. Moreover, the design provisions of three different code standards (Greek Code of Interventions, Eurocode 8 and ACI Committee 440) concerning the shear capacity of T-shaped RC beams retrofitted with EB-FRP jackets or strips in U-jacketing configuration are investigated. The ability of these code standards to predict safe design estimations is checked against 165 test data from the current experimental project and data available in the literature.Strengthening of existing low-capacity RC structures using externally bonded fiber-reinforced polymers (EB-FRP) has become very popular because of the advantages of these materials such as their superior strength-to-weight ratio, their easy-to-apply character, their durability and their chemical and corrosion resistance [6][7][8]. For shear-critical RC elements with rectangular cross-sections in particular, full jacketing application of EB-FRP sheets wrapping around the cross-section and along their entire length provides increased strength and enhanced structural performance since it alters the shear brittle response to a ductile one [9][10][11][12]. However, common constructional limitations, such as the existence of a slab, usually prevent the wrapping of EB-FRP sheets around the cross-section. Thus, most RC beams with a T-shaped cross-section are shear strengthened using EB-FRP sheets (jackets or strips) on the three sides of the web of the beam (U-shaped retrofitting). A significant deficiency of this technique is the premature failure of the strengthened member due to the debonding of the EB-FRP at the adhesive composite and concrete interface [13][14][15][16][17][18][19][20].Several experimental studies have demonstrated the effectiveness...

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Rehabilitation of defected RC stepped beams using CFRP

Cited by 12 publications

References 15 publications

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

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

The effect of rotatory inertia on natural frequency of cracked and stepped nanobeam

U-Jacketing Applications of Fiber-Reinforced Polymers in Reinforced Concrete T-Beams against Shear—Tests and Design

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