Effect of basic design parameters on IC debonding of CFRP-strengthened shallow RC beams

Al-Saawani, Mohammed A.; El-Sayed, Ahmed K.; Al‐Negheimish, Abdulaziz I.

doi:10.1177/0731684415593816

Cited by 29 publications

(11 citation statements)

References 23 publications

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“…In the study conducted by Benjeddou et al (2007), a change in the failure mode from CCS to PE interfacial debonding was observed in one of the strengthened beams when the width of the FRP laminated was decreased from 100 to 50 mm. Also, a shift of the failure mode from IC debonding to CCS failure was reported in the study conducted by Al-Saawani et al (2015) when the width of CFRP plates was increased from 240 to 360 mm. Considerable reduction in the utilization of the CFRP material resulted from such shift of the failure mode.…”

Section: Previous Studies On Plate End Debondingmentioning

confidence: 77%

“…In general, ACI 440.2 (ACI Committee 440, 2017) indicates that the FRP end peeling failure can be mitigated by minimizing the stress at the FRP curtailment by locating the curtailment as close to the region of zero moment as possible, by using an end anchorage, or by both. However, it was observed in several studies [Brena et al 2003;Al-Saawani et al 2015;Hasnat et al 2016;Aprile and Feo 2007] that PE debonding was not prevented by relying solely on extending the FRP plate close to the supports. This is because although the bending moment is almost zero close to the support in simply supported beams, shear cracks are developed in this zone.…”

Section: Approach Related To the Cut-off Point Of Eb Frpmentioning

confidence: 99%

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Assessment of plate-end debonding design provisions for RC beams strengthened with FRP

Al-Saawani

El-Sayed

Al‐Negheimish

2020

Lat. Am. j. solids struct.

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Despite the enhancement in the flexural capacity of reinforced concrete (RC) members externally strengthened with fiber reinforced polymer (FRP) composites, debonding of the FRP from the concrete substrate at its ends is a major concern. This premature failure mostly occurs at a low fraction of the FRP rupture strain, thus compromises the effectiveness of FRP-strengthening. This paper presents a review on plate-end (PE) debonding as a critical failure mode in FRP-strengthened beams. The available models for predicting this mode of failure are also presented and assessed against experimental database established from previous studies. The precautions recommended by the relevant design codes to prevent PE debonding are also discussed and assessed. Based on the assessment, several conclusions are emphasized, including the inaccuracy in predictions of PE debonding given by most available models when compared with the experimental database and the inconsistency among these models. The assessment also revealed that the precautions recommended by most of the design codes are not adequate to prevent PE debonding.

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Section: Previous Studies On Plate End Debondingmentioning

confidence: 77%

Section: Approach Related To the Cut-off Point Of Eb Frpmentioning

confidence: 99%

Assessment of plate-end debonding design provisions for RC beams strengthened with FRP

Al-Saawani

El-Sayed

Al‐Negheimish

2020

Lat. Am. j. solids struct.

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“…There are two main debonding failure modes: intermediate crack (IC)-induced debonding and plate end (PE) debonding. IC debonding occurs in FRP-strengthened RC beams in the region of high moment due to the opening of flexural cracks [6][7][8][9][10][11][12][13]. On the other hand, PE debonding initiates at the plate end region due to high interfacial and normal stresses [14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Effect of Stirrups on Plate End Debonding in Reinforced Concrete Beams Strengthened with Fiber Reinforced Polymers

Al‐Negheimish¹,

El-Sayed²,

Al-Saawani³

et al. 2021

Polymers

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Plate end (PE) debonding is one of the critical debonding failure modes that may occur in reinforced concrete (RC) beams strengthened with externally bonded fiber reinforced polymers (FRPs). This study investigated the effect of internal steel stirrups on the PE debonding failure load of FRP-strengthened RC beams. The dimensions of the beams were 3400 × 400 × 200 mm. The beams were strengthened with carbon FRP (CFRP) sheets bonded to the soffit of the beams. The beams were divided into two series based on the distance of the cutoff point of the CFRP sheets from the nearest support. This distance was 50 mm or 300 mm, and the amount of steel stirrups was varied in terms of varying the stirrup diameter and spacing. The beams were simply supported and tested under four-point bending. The test results indicate that the effect of stirrups on the load carrying capacity of the beams was more pronounced for the beams with CFRP sheets extended close to the supports. It was also indicated that beams with larger amounts of stirrups failed in PE debonding by concrete cover separation while beams with lower amounts of stirrups failed in PE by either PE interfacial debonding or critical diagonal crack-induced debonding. The beams were analyzed using several analytical models from design guidelines and the literature. The result of analysis indicates that most of the available models failed to reflect the effect of stirrups in predicting PE debonding failure load of the beams. On the other hand, the models of El-Sayed et al. and Teng and Yao were able to capture such an effect with the best predictions provided by El-Sayed et al. model.

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“…This is attributed to the excellent characteristics of FRP materials that include high tensile strength, lightweight, corrosion resistance, and ease of installation. Numerous research work has been conducted to investigate the flexural performance of RC beams strengthened with EB FRP composites [1][2][3][4][5][6][7]. These studies have led to increase in the knowledge of the structural behavior of FRP-strengthened RC beams.…”

Section: Introductionmentioning

confidence: 99%

Mitigation of Concrete Cover Separation in Concrete Beams Strengthened with Fiber-reinforced Polymer Composites

Al-Saawani

El-Sayed

Al‐Negheimish

2022

IOP Conf. Ser.: Earth Environ. Sci.

Self Cite

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Strengthening of reinforced concrete (RC) beams using fiber reinforced polymers (FRP) is an effective method that is gaining more acceptance worldwide. However, failure of the strengthened beams at the plate-end region by concrete cover separation (CCS) compromises the effectiveness of such a strengthening system. Among available anchorage systems to remedy such problem, the use of FRP U-wraps at the end region of the externally bonded FRP has the potential to prevent CCS failure. Most studies in the literature suffer from poor design of test specimens and the use of random amounts of FRP anchorage. This resulted in nonconclusive findings and contradicting results on the real effectiveness of FRP U-wraps as an anchorage to prevent plate-end debonding failure. That in turn has been reflected in the lack of reliable design methods for the design of FRP U-wrap anchorage. In this paper, the effect of FRP U-wraps on the mitigation of CCS failure in FRP-strengthened RC beams was experimentally examined and quantified. The study included full-scale RC beams strengthened in flexure using carbon FRP (CFRP) sheets and anchored at the plate-end region using vertical CFRP U-wraps. The test variable was the amount of CFRP U-wrap that is required to achieve complete mitigation of CCS. The test results indicated the effectiveness of FRP U-wraps on mitigating CCS failure once the required area of CFRP U-wrap was placed. Relevant design models were presented and assessed against the experimental results of the current study. The comparisons indicated inaccurate predictions for the area of FRP U-wrap that is required to prevent CCS. This sheds the light on the need for developing a more reliable and accurate method for the design of an end anchorage to prevent CCS failure.

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Effect of basic design parameters on IC debonding of CFRP-strengthened shallow RC beams

Cited by 29 publications

References 23 publications

Assessment of plate-end debonding design provisions for RC beams strengthened with FRP

Assessment of plate-end debonding design provisions for RC beams strengthened with FRP

Effect of Stirrups on Plate End Debonding in Reinforced Concrete Beams Strengthened with Fiber Reinforced Polymers

Mitigation of Concrete Cover Separation in Concrete Beams Strengthened with Fiber-reinforced Polymer Composites

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