Near Surface Mounted Composites for Flexural Strengthening of Reinforced Concrete Beams

An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. A total of ten full-scale stone slabs were tested under a four-point bending loading to investigate the effect of groove dimension, reinforcement ratios, and reinforcement materials on the flexural performance of stone slabs. e test results included failure characteristics, yield and ultimate capacities, deflection of midspan, and cracking behavior of stone slabs. e test results indicate that with the increase of groove height and groove width, cracking load and middeflection decrease by 6.4%-14.18%; however, failure load and middeflection increase by 4.7%-41.2%. Cracking load, failure load, and failure displacement of stone slabs adopting NSM screwthread steels increased by 10.9%, 167%, and 617%, respectively, under the maximum reinforcement ratios of 0.629% over the control slab without NSM bars. Meanwhile, with the increase of reinforcement ratios, the failure mode transforms from brittle failure to ductile failure. e calculation results of strength are in agreement with the experimental results. Finally, it can be concluded that NSM CFRP bars are more effective than NSM screw-thread steels to improve flexural capacity with the same reinforcement ratios.

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“…us, it is necessary to use NSM CFRP bars to increase the ultimate load capacity of stone slabs. e results were similar to those in [30].…”

Section: E E Ect Of Type Of Nsm Reinforcement On Stone Slabs (Cb-3 Ansupporting

confidence: 87%

“…e failure mode is similar to reinforcement concrete beams' failure mode in bending with GFRPS [30] or CFRPS [30]. e failure mode is ductile failure.…”

Section: Specimen Gb-6mentioning

confidence: 87%

Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw‐Thread Steels

Gao

Chen

Ding

et al. 2018

Advances in Materials Science and Engineering

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“…Many studies have applied the NSM FRP strengthening method to improve the flexural and shear strength of RC beams [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], whilst others have used conventional steel bars instead of FRP materials for flexural and shear strengthening [21][22][23][24][25][26][27][28]. However, only few of these studies have focused on torsion strengthening [29][30][31]32] and no previous work has investigated the application of conventional steel bars for the torsion strengthening of RC beams.…”

Section: Introductionmentioning

confidence: 99%

Torsional Strengthening of RC Beams with Near‐Surface Mounted Steel Bars

Askandar

Mahmood

2020

Advances in Materials Science and Engineering

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e strength of reinforced concrete members can be enhanced by using the externally bonded reinforcement (EBR) and nearsurface mounted (NSM) methods. However, very few studies have adopted the NSM method for torsional strengthening. Although previous studies have reported the efficacy of using epoxy-resin-bonded NSM steel bars in increasing the flexural and shear strength of RC beams, no study has examined the use of steel bars and epoxy adhesives for torsional strengthening.erefore, this study investigates the behaviour of RC beams subjected to the combined actions of torsion and bending moment when they are strengthened with NSM steel bars (Ø10 mm) in different configurations. e practical part of this investigation consisted of seven cast and tested beams of 150 × 250 × 2000 mm dimensions. One beam was reference, which is not strengthened; meanwhile, all the other beams were strengthened with two U-shape-welded NSM steel bars. During the testing process, the twist angle at the torque intervals, first cracking torque, ultimate torque, and ultimate twist angle of the conventional beam were compared with those of the strengthened beams. e torsional performance of the RC beams was significantly improved by using NSM steel bars, whereas in various NSM configurations, the 90°NSM beams outperformed the 45°NSM beams.

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“…is strengthening technique has already been proven to be effective for the shear and flexural strengthening of RC beams [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. Many studies have also used conventional steel bars instead of FRP materials for flexural and shear strengthening by employing the NSM method [59][60][61][62][63][64]. However, only few of these studies have focused on torsion strengthening [65,66], and no previous work has investigated the application of conventional steel bars for the torsion strengthening of RC beams.…”

Section: Introductionmentioning

confidence: 99%

Comparative Investigation on Torsional Behaviour of RC Beam Strengthened with CFRP Fabric Wrapping and Near‐Surface Mounted (NSM) Steel Bar

Askandar

Mahmood

2019

Advances in Civil Engineering

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Many researchers worldwide have extensively used fibre-reinforced polymer (FRP) strengthening materials and near-surface mounted (NSM) to enhance the shear and flexural strengths of reinforced concrete (RC) beams. However, studies on torsional strengthening are limited. Although a few studies have focused on torsional strengthening, none of them simultaneously investigated torsion with shear and/or bending moment. This study aims at demonstrating the behaviour of RC beams strengthened with FRP sheets (strips) with different configurations and NSM steel bars with different spacing that was subjected to combined actions of torsion and bending moment and making a comparison between them. Seven beams with a dimension of 15 × 25 × 200 cm were casted. One of the beams was not strengthened; three of them were strengthened with carbon FRP, and the others were strengthened with NSM steel bar. The angle of twist at torque intervals, first cracking torque, ultimate torque, and ultimate twist angle of the conventional and strengthened beams during the testing process are compared. Results show a significant improvement in the torsional performance of RC beams using carbon FRP and NSM steel bar. The test beams that were strengthened with CFRP wrapping showed better enhancement in the ultimate torsional moment as opposed to the beams that were strengthened with NSM steel bar.

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Near Surface Mounted Composites for Flexural Strengthening of Reinforced Concrete Beams

Cited by 29 publications

References 26 publications

Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw‐Thread Steels

Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw‐Thread Steels

Torsional Strengthening of RC Beams with Near‐Surface Mounted Steel Bars

Comparative Investigation on Torsional Behaviour of RC Beam Strengthened with CFRP Fabric Wrapping and Near‐Surface Mounted (NSM) Steel Bar

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