scholarly journals Torsional Strengthening of RC Beams with Near-Surface Mounted Steel Bars

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Nasih Habeeb Askandar ◽  
Abdulkareem Darweesh Mahmood
Keyword(s):  
Twist Angle ◽  
Bending Moment ◽  
Rc Beams ◽  
Near Surface ◽  
Concrete Members ◽  
Epoxy Adhesives ◽  
Steel Bars ◽  
Externally Bonded ◽  
Near Surface Mounted ◽  
Combined Actions

The strength of reinforced concrete members can be enhanced by using the externally bonded reinforcement (EBR) and near-surface 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. Therefore, 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. The 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. The 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.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Nasih Askandar ◽  
Abdulkareem Mahmood
Keyword(s):  
Twist Angle ◽  
Bending Moment ◽  
Comparative Investigation ◽  
Rc Beams ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Steel Bar ◽  
Fibre Reinforced Polymer ◽  
Near Surface Mounted ◽  
Cfrp Wrapping

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.

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

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 Modeling of CFRP strengthened RC beams using the SNSM technique, proposed as an alternative to NSM and EBR techniques

2020 ◽  
Vol 14 (54) ◽  
pp. 21-35
Author(s):  
Adel Boulebd ◽  
Ferhoune Noureddine ◽  
Boukhezar Mohcene ◽  
Habib Abdelhak Mesbah
Keyword(s):  
Finite Element ◽  
Failure Mode ◽  
Numerical Study ◽  
Concrete Cover ◽  
Rc Beams ◽  
Near Surface ◽  
Externally Bonded ◽  
Bending Capacity ◽  
Near Surface Mounted ◽  
Abaqus Software

In this paper, an analytical and numerical study in FEM finite element by the ABAQUS software was conducted. Which aims to study the behaviour of RC beams bending strengthened with SNSM side near surface mounted technique, proposed as a solution to avoid the failure mode by debonding of the strengthening, the disadvantage of the EBR externally bonded reinforced technique, and the failure mode by separation of the concrete cover relative to the NSM near surface mounted technique, by comparing the behaviour of the three techniques, the effect of the quantity of strengthening and confirm the results with the literature. The results of this study show that the numerical and analytical model can predict the behaviour of strengthened RC beams according to the three techniques, a clear improvement of the bending capacity of beams strengthened is noticed. A good preservation of the ductility of SNSM beams with a better failure mode.

scholarly journals Crack parameters in normal section of FRP strengthened RC elements

2019 ◽  
Author(s):  
Justas Slaitas ◽  
Juozas Valivonis
Keyword(s):  
Prediction Model ◽  
Crack Width ◽  
Rc Beams ◽  
Near Surface ◽  
Normal Section ◽  
Full Development ◽  
Externally Bonded ◽  
Frp Reinforcement ◽  
Near Surface Mounted ◽  
Element Failure

Contrary to existing studies, this paper presents a prediction model of crack parameters in normal section of FRP strengthened RC elements neglecting crack spacing. A relation between normal crack width, depth and strains in the level of FRP reinforcement, established by Slaitas et al. (Slaitas, Daugevičius, Valivonis, & Grigorjeva, 2018a) and Jokūbaitis et al. (Jokūbaitis & Juknevičius, 2013; Jokūbaitis, Juknevičius, & Šalna, 2013), allowed authors to describe the full development of the crack up to the element failure. Numerical results are compared with experimental ones from the tests of 9 RC beams, strengthened with externally bonded and near surface mounted FRP reinforcements.

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.

Sign in / Sign up

Export Citation Format

Share Document