• Title/Summary/Keyword: strengthening technique

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Flexural Strengthening Capacities in Prestressed concrete Beams Applied to Outcable technique (아웃케이블 공법을 적용한 프리스트레스 철근콘크리트 보의 휨보강 성능)

  • Park Wan-Shin;Yun Hyun-Do;Han Byung-Chan;Hwang Sun-Kyung;Lim Jea-Hyung;Moon Jeong-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.268-271
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    • 2004
  • A strengthening technique for reinforced concrete beams using external unhanded reinforcement offers advantages in speed and simplicity of installation over other, established, strengthening techniques. The purpose of this paper is to investigate the capabilities of a new retrofitting technique, namely external prestressing out cable, for flexural strengthening of beams. The paper provides a general description of structural behavior of beams strengthened using the technique. Results of four physical tests on strengthened reinforced concrete beams are reported and compared. It is shown that the technique can provide greater strength enhancement to lightly reinforced sections and that provision of deflectors enhances efficiency.

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A Study on Strengthening of R/C T Girder Bridge using Standardized Strengthening Technique with Fiber Plastic(I) (표준화된 섬유보강공법을 적용한 RC T형 교량의 성능향상연구(I))

  • 심종성;오홍섭;임채옥
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.545-548
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    • 1999
  • The purpose of this study is application of strengthening technique of R/C concrete bridge by standardization of repair and rehabilitation. For that, experiment to bridge is necessary, and through the experiment, this study can identify the efficiency o applied method and analysis of design parameters with can't get in the laboratory experiment. This study will prove the structural behavior of R/C type girder bridge which is deteriorated but repaired and rehabilitation from standardized strengthening method with fiber plastic.

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Strengthening Effect Evaluation Technique of R/C Beams using the Vibration Test (진동시험을 통한 R/C Beam의 보강효과 검증기법)

  • 심종성;유태석
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.10a
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    • pp.255-260
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    • 1994
  • This study suggests a strengthening effect evaluation technique of reinforced concrete beams using the vibration test. To evaluate the strengthening effect of R/C beams, Strengthening Factor(Sf) was suggested. Using the value of Sf, 20 beams were evaluated. According to these results the effects of R/C beams strengthened by steel plate is superior than those of R/C beams strengthened by carbon fiber sheet.

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Effect of link length in retrofitted RC frames with Y eccentrically braced frame

  • INCE, Gulhan
    • Steel and Composite Structures
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    • v.43 no.5
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    • pp.553-564
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    • 2022
  • Many existing reinforced concrete (RC) structures need to be strengthening for reason such as poor construction quality, low ductility or designing without considering seismic effects. One of the strengthening methods is strengthening technique with eccentrically braced frames (EBFs). The characteristic element of these systems is the link element and its length is very important in terms of seismic behavior. The link element of Y shaped EBF systems (YEBFs) is designed as a short shear element. Different limits are suggested in the literature for the link length. This study to aim experimentally investigate the effect of the link length for the suggested limits on the behavior of the RC frame system and efficiency of strengthening technique. For this purpose, a total of 5 single story, single span RC frame specimens were produced. The design of the RC frames was made considering seismic design deficiencies. Four of the produced specimens were strengthened and one of them remained as bare specimen. The steel YEBFs were used in strengthening the RC frame and the link was designed as a shear element that have different length with respect to suggested limits in literature. The length of links was determined as 50mm, 100mm, 150mm and 200mm. All of the specimens were tested under cyclic loads. The obtained results show that the strengthening technique improved the energy consumption and lateral load bearing capacities of the bare RC specimen. Moreover, it is concluded that the specimens YB-2 and YB-3 showed better performance than the other specimens, especially in energy consumption and ductility.

Repair, retrofitting and rehabilitation techniques for strengthening of reinforced concrete beams - A review

  • Ganesh, P.;Murthy, A. Ramachandra
    • Advances in concrete construction
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    • v.8 no.2
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    • pp.101-117
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    • 2019
  • Structural strengthening of reinforced concrete (RC) beams is becoming essential to meet the up-gradation of existing structures due to the infrastructure development. Strengthening is also essential for damaged structural element due to the adverse environmental condition and other distressing factors. This article reviews the state of the field on repair, retrofitting and rehabilitation techniques for the strengthening of RC beams. Strengthening of RC beams using various promising techniques such as externally bonded steel plates, concrete jacketing, fibre reinforced laminates or sheets, external prestressing/external bar reinforcement technique and ultra-high performance concrete overlay have been extensively investigated for the past four decades. The primary objective of this article is to discuss investigations on various strengthening techniques over the years. Various parameters that have been discussed include the flexural capacity, shear strength, failure modes of various strengthening techniques and advances in techniques over the years. Firstly, background information on strengthening, including repair, retrofitting, and rehabilitation of RC beams is provided. Secondly, the existing strengthening techniques for reinforced concrete beams are discussed. Finally, the relative comparisons and limitations in the existing techniques are presented.

A Clinical Study Comparing the Effects of Supine JS Cervical Therapy and Muscle Release/Strengthening Technique on the Patients with Acute Neck Pain Caused by Traffic Accidents: A Retrospective Study (교통사고로 유발된 급성 경항통 환자에 대한 앙와위 경추 JS 신연 교정기법과 근육 이완/강화기법의 효과 비교: 후향적 연구)

  • Park, Jeong-Wook;Gu, Ji-Hyang;Ha, Hyun-Ju;Oh, Min-Seok
    • Journal of Korean Medicine Rehabilitation
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    • v.30 no.3
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    • pp.129-139
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    • 2020
  • Objectives The purpose of this study was to compare the effect of supine JS cervical therapy and muscle release/strengthening technique in patients with acute neck pain caused by traffic accidents. Methods We studied 42 patients with acute neck pain caused by traffic accidents from July 1, 2019 to November 30, 2019. The study was conducted as a retrospective study which analyzes the patient's medical records. 21 patients (group A) had received supine JS cervical therapy and 21 patients (group B) had received muscle release/strengthening technique. We used the neck disability index (NDI) and visual analog scale (VAS) to evaluate improvements in symptoms and pain, and used the five point Likert scale to evaluate patient's satisfaction with chuna manual therapy. In each group, we compared the NDI and VAS of hospitalization day to those of 5 days later. Then we compared the NDI, VAS variation and five point Likert scale between the groups. Statistical analysis was conducted using the IBM SPSS for windows 25.0. Result Both group A and group B showed a statistically significant decrease in the NDI and VAS on the 5th day of hospitalization. In group A, there was a statistically significant decrease in the NDI compared to group B. The VAS and Five Point Likert Scale decrease was greater in group A than in group B, but the difference was not statistically significant. Conclusion We found that using supine JS cervical therapy may be more effective than muscle release/strengthening technique in acute stage after traffic accidents.

A Study on the Failure Behavior and the Application of Yield-Line Theory on the Bridge Decks Strengthened by Directional Fiber Plastic (일방향 섬유로 성능향상된 교량 상판의 파괴거동 및 항복선 이론을 적용한 해석적 연구)

  • 심종성;오홍섭;류승무
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.81-86
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    • 2001
  • The concrete bridge decks are in need of replacement and rehabilitation due to decreasing load carrying capacity. In this study, to propose a strengthening technique that improves usability and structural performance of the bridge deck and to propose an efficient strengthening design technique which satisfies both the strength End serviceability of the bridge deck, this paper shows the failure characteristics of the strengthened bridge decks and proposes an empirical yield criterion. Therefore, strengthening efficiency was proposed based on the experiment and yield line analysis result. The yield line theory which adopts the modified criteria of Johansen is considered to predict the ultimate strength about all strengthening material(Carbon Fiber Sheet, Carbon Fiber Rod, Grid Type Carbon Fiber).

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The Study on Improvement of Flexural Performance of RC Beam Strengthened with CFRP Plate (탄소섬유보강판으로 보강된 철근콘크리트 보의 휨성능 개선에 관한 연구)

  • 한상훈;최만용;조홍동;박중열;황선일;김경식
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.399-404
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    • 2002
  • This paper presents the results cf research on improved flexural performance cf reinforced concrete beams strengthened with bonded carbon fiber reinforced polymer plate. Recently, strengthening technique with CFRP plate were almost carried out by external bonding. But current external bonding technique cf CFRP plates may result in debonding CFRP plate. Therefore, this study proposes a strengthening method that prevents or delays debonding between CFRP plates and concrete and at the same time improves the strength. For this test, there were only 14 test beams manufactured and failure load, deflection, strains and modes cf failure have been examined Test variables included the type cf strengthening, steel ratio and strengthening length, and the effects according to each test variables were analyzed. The experimental results show that the strength and stiffness cf the beam significantly increased between 34.55 and 116.51% and the increase cf the more lead-carrying capacity than the control beams.

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Strengthening of deficient RC frames with high strength concrete panels: an experimental study

  • Baran, Mehmet;Susoy, Melih;Tankut, Tugrul
    • Structural Engineering and Mechanics
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    • v.37 no.2
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    • pp.177-196
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    • 2011
  • An economic, structurally effective and practically applicable strengthening technique was developed for reinforced concrete (RC) framed buildings. The idea of the technique is to convert the existing hollow brick infill wall into a load carrying system acting as a cast-in-place RC infill wall by bonding relatively thin high strength precast concrete PC panels to the plastered hollow brick infill. For this purpose, a total of eight one-third scale, one bay, one story frames were tested under reversed-cyclic lateral loads. Test frames were designed and constructed with common deficiencies observed in practice. Four different panel types were used for strengthening. Test results showed that both strength and stiffness of the frames were significantly improved by the introduction of PC panels. Experimental results were compared with the analytical approaches suggested by the authors.

Experimental investigation on optimal shear strengthening of RC beams using NSM GFRP bars

  • Ramezanpour, M.;Morshed, R.;Eslami, A.
    • Structural Engineering and Mechanics
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    • v.67 no.1
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    • pp.45-52
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    • 2018
  • Several techniques have been developed for shear strengthening of reinforced concrete (RC) members by using fiber reinforced polymer (FRP) composites. However, debonding of FRP retrofits from concrete substrate still deemed as a challenging concern in their application which needs to be scrutinized in details. As a result, this paper reports on the results of an experimental investigation on shear strengthening of RC beams using near surface mounted (NSM) FRP reinforcing bars. The main objective of the experimentation was increasing the efficiency of shear retrofits by precluding/postponing the premature debonding failure. The experimental program was comprised of six shear deficient RC beams. The test parameters include the FRP rebar spacing, inclination angle, and groove shape. Also, an innovative modification was introduced to the conventional NSM technique and its efficiency was evaluated by experimental observation and measurement. The results testified the efficiency of glass FRP (GFRP) rebars in increasing the shear strength of the test specimens retrofitted using conventional NSM technique. However, debonding of FRP bars impeded exploiting all retrofitting advantages and induced a premature shear failure. On the contrary, application of the proposed modified NSM (MNSM) technique was not only capable of preventing the premature debonding of FRP bars, but also could replace the failure mode of specimen from the brittle shear to a ductile flexural failure which is more desirable.