Effect of Carbon Fiber Sheets on Flexural Strengthening of RC Beams Damaged by Corrosion of Tension Rebar

2007 ◽  
Vol 348-349 ◽  
pp. 437-440
Author(s):  
Han Seung Lee ◽  
Sang Heon Shin ◽  
Je Woon Kyung
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Fem Analysis ◽  
Strengthening Effect ◽  
Deformation Capacity ◽  
Rc Beams ◽  
Test Results ◽  
Practical Application ◽  
Flexural Strengthening ◽  
Loading Tests

RC beam with corroded tension rebars were strengthened with carbon fiber sheets(CFS) and were subjected to static loading tests to investigate the flexural strengthening effect of CFS. The test results confirmed that CFS are effective in reducing stresses to be carried by tension rebars and increasing flexural strength. Since the deformation capacity of the strengthened specimens was increased by anchoring the CFS and since the maximum strength of the specimens was determined by detachment or rupture of CFS, the flexural strength of the strengthened specimens could be calculated from an existing formula. Experimentally determined load-deflection relationships for RC beams were reproduced accurately through a FEM analysis modeling the bond elements between the concrete and the CFS. Practical application of the CFS sheeting method to RC beams requires improvement of the strength of bond between CFS and concrete.

scholarly journals Flexural Strengthening of Concrete Slab-Type Elements with Textile Reinforced Concrete

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2246 ◽  
Author(s):  
Hyeong-Yeol Kim ◽  
Young-Jun You ◽  
Gum-Sung Ryu ◽  
Kyung-Taek Koh ◽  
Gi-Hong Ahn ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Tensile Test ◽  
Tensile Properties ◽  
Surface Coating ◽  
Strengthening Effect ◽  
Test Results ◽  
Short Fibers ◽  
Textile Reinforced Concrete ◽  
Flexural Strengthening ◽  
The Matrix

This paper deals with flexural strengthening of reinforced concrete (RC) slabs with a carbon textile reinforced concrete (TRC) system. The surface coating treatment was applied to a carbon grid-type textile to increase the bond strength. Short fibers were incorporated into the matrix to mitigate the formation of shrinkage-induced cracks. The tensile properties of the TRC system were evaluated by a direct tensile test with a dumbbell-type grip method. The tensile test results indicated that the effect of the surface coating treatment of the textile on the bonding behavior of the textile within the TRC system was significant. Furthermore, the incorporation of short fibers in the matrix was effective to mitigate shrinkage-induced crack formation and to improve the tensile properties of the TRC system. Six full-scale slab specimens were strengthened with the TRC system and, subsequently, failure tested. The ultimate load-carrying capacity of the strengthened slabs was compared with that of an unstrengthened slab as well as the theoretical solutions. The failure test results indicated that the stiffness and the ultimate flexural capacity of the strengthened slab were at least 112% and 165% greater, respectively, than that of the unstrengthened slab. The test results further indicated that the strengthening effect was not linearly proportional to the amount of textile reinforcement.

scholarly journals An experimental study on flexural strengthening of RC beams using CFRP sheets

2018 ◽  
Vol 7 (4) ◽  
pp. 2075 ◽  
Author(s):  
Yasmin Murad
Keyword(s):  
Flexural Strength ◽  
Orientation Angle ◽  
Longitudinal Axis ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Cfrp Sheets ◽  
Reinforced Polymer

 The use of carbon fiber reinforced polymer (CFRP) sheets is becoming a widely accepted solution for strengthening and repairing rein-forced concrete (RC) structures. To date, the behavior of RC beams, strengthened with 60˚ and 45˚ inclined CFRP sheets, has not clearly explained. An experimental program is proposed in this paper to investigate the flexural behavior of RC beams strengthened with CFRP sheets. CFRP sheets were epoxy bonded to the tension face to enhance the flexural strength of beams inducing different orientation angles of 0˚, 45˚, 60˚ and 90˚ with the beam longitudinal axis. The study shows that strengthening RC beams with CFRP sheets is highly influenced by the orientation angle of the sheets. The orientation angle plays a key role in changing the crack pattern and hence the failure mode. The influence of CFRP sheets was adequate on increasing the flexural strength of RC beams but the ductility of the beams was reduced. The best performance was obtained when strengthening RC beam obliquely using 45˚ inclined CFRP sheets where the specimen experienced additional deflection and strength of 56% and 12% respectively and the reduction in its ductility was the least. It is recom-mended to strengthen RC beams, which are weak in flexure, using 45˚ inclined CFRP sheets.  

Improvement of Flexural Strength of RC Beams by Using the Multi-Layer Multi-Tensioning Method with CF Sheets

2007 ◽  
Vol 334-335 ◽  
pp. 429-432
Author(s):  
Takayuki Kusaka ◽  
Keiko Watanabe ◽  
Ken Suke Okubo ◽  
Hironori Namiki
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Crack Initiation ◽  
Concrete Structures ◽  
Experimental Results ◽  
Reinforced Concrete Structures ◽  
Rc Beams ◽  
Conventional Methods ◽  
Energy Absorbing

A novel retrofitting method using extremely prestressed carbon fiber sheets, MLML (Multi-Layer Multi-Tensioning) method, was proposed for improving the flexural strength of reinforced concrete structures. The experimental results suggested that the crack initiation strength and the energy absorbing capacity of RC beams could be largely improved by the MLMT method. However, the advantage of the MLMT method was not so clear on the rebars yielding strength and the ultimate flexural strength of RC beams, compared with the conventional methods.

Fatigue Behavior of RC Slab Retrofitted with Carbon Fiber Mesh after Different Levels of Pre-Damage

2007 ◽  
Vol 347 ◽  
pp. 179-184
Author(s):  
Soo Yeon Seo ◽  
Hyun Do Yoon ◽  
Cheol Woo Park
Keyword(s):  
Carbon Fiber ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Test Results ◽  
Rc Slab ◽  
Loading Tests ◽  
Strength And Stiffness ◽  
Fiber Mesh ◽  
Different Levels ◽  
Test Result

Three RC slab specimens were designed and manufactured to investigate the fatigue behavior of RC slab retrofitted with carbon fiber mesh (CFM) and mortar. Among three slab specimens, two slabs were pre-loaded to introduce damage prior to the fatigue loading tests. Fatigue loading was applied to the top of slab maintaining 40% of the ultimate strength of specimen at 2Hz loading speed. The fatigue test was terminated when the loading cycle exceeded 1,000,000 cycles. From the test results, the effectiveness of the retrofitting using CFM was evaluated. Test result showed that the specimens retrofitted after either severe or light damages had very similar strength and stiffness to those of the specimens retrofitted without damage. It was found that the strength was even slightly improved in the specimen retrofitted with CFM.

Strength of Masonry Walls Retrofitted with Epoxy Resin Injection

2011 ◽  
Vol 82 ◽  
pp. 545-550 ◽  
Author(s):  
Hideo Araki ◽  
Akira Yasojima ◽  
Junichi Kagawa
Keyword(s):  
Flexural Strength ◽  
Epoxy Resin ◽  
Seismic Loading ◽  
Masonry Walls ◽  
Brick Wall ◽  
Test Results ◽  
Injection Method ◽  
Resin Injection ◽  
Loading Tests ◽  
Strengthening Method

This paper presents the results of the fundamental loading tests with brick elements strengthened by the epoxy resin injection method. Three types of loading tests were performed to evaluate the effects of epoxy resin injection on compressive, shear, and flexural characteristics. The variables considered in this experiment were the strength of the mortar and the applied axial force. To verify the effects of this strengthening method, seismic loading tests were performed on three brick walls. From the test results, an increase in the strength of the element was observed in each test. However, the strength of the mortar did not affect the shear and flexural strength of the brick elements. We proposed equations to estimate the strength of the elements strengthened by the epoxy resin injection method. Improvements to the seismic performance of the brick wall strengthened with epoxy resin were explicitly confirmed.

scholarly journals Effects of opening location on flexural behavior of RC columns with sidewalls

2017 ◽  
Vol 50 (4) ◽  
pp. 547-554 ◽  
Author(s):  
Daisuke Kato ◽  
Daisuke Sato ◽  
Tadashi Takamatsu
Keyword(s):  
Flexural Strength ◽  
Flexural Behavior ◽  
Deformation Capacity ◽  
Rc Columns ◽  
Load Carrying ◽  
Capacity Calculation ◽  
Single Opening ◽  
Strength And Deformation ◽  
Side Walls ◽  
Loading Tests

Practical use of secondary walls such as sidewalls is common because the contributions of secondary walls for stiffness or strength have been recognized. In 2016, “AIJ Standard for Lateral Load-carrying Capacity Calculation of Reinforced Concrete Structures” was published as a draft by Architectural Institute of Japan. In this standard new equations for columns with side walls were proposed. From this viewpoint, the authors have conducted static loading tests of flexurally controlled RC column specimens with single opening in the sidewall, to investigate the effects of openings on strength and deformation capacity of RC columns with a side walls. In this paper, the limitations on location of openings inside sidewalls to avoid their effects on flexural strength and deformation capacity are examined using design equations for flexural strength based on full plastic moment of the column and sidewall. The test results indicate that the proposed limitation line on location of openings to avoid their effects for flexure could be effective for practical design.

scholarly journals Flexural strengthening of RC beams by using a near surface mounted T-section profiles

2014 ◽  
Vol 13 (3) ◽  
pp. 071-078
Author(s):  
Szymon Chołostiakow ◽  
Renata Kotynia
Keyword(s):  
Reference Beam ◽  
Concrete Surface ◽  
Experimental Program ◽  
Rc Beams ◽  
Test Results ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Existing Structures ◽  
Near Surface Mounted ◽  
Strengthening Technique

The paper presents test results of an experimental program of four full-scale RC beams, strengthened in flexure with T-section carbon fiber reinforced polymer (CFRP) profiles and two reference beams subjected to a six point bending. The novel shape of CFRP profile combines both the near surface mounted (NSM) and externally bonded (EB) strengthening systems. The application of the CFRP profiles consisted of gluing both the web and the flange of the profile to the concrete surface. RC beams made of the same concrete class were differed by the internal steel reinforcement ratio and in a number of applied profiles. Efficiency of this new strengthening product was determined by comparison of the strengthened and non-strengthened RC beams. An increase of the CFRP-concrete bond area and high stiffness of the T-section profiles significantly improved the strengthening ratio (up to 130% of the reference beam) and reduced the maximum mid-span deflection (ranged of 70-80%) of the non–strengthened beams. The CFRP strain utilisation equal to 67% of the tensile strain corresponded to the maximum CFRP strains equal to 0,73%. The promising test results exhibit this system as a very attractive proposal of new strengthening technique used for field applications of the  existing structures.

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