• Title/Summary/Keyword: 외부 긴장재

Search Result 30, Processing Time 0.028 seconds

Fatigue Behavior of Reinforced Concrete Beams Externally Strengthened using FRP Tendons (FRP 긴장재로 외부 보강된 철근콘크리트 보의 피로거동)

  • Park, Sang Yeol;Hong, Sung Ryong;Kim, Chang Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.6A
    • /
    • pp.809-817
    • /
    • 2008
  • Recently, the external prestressing method is being much frequently used in strengthening reinforced concrete structures because of it's excellent load resistance and serviceability increases comparing to other strengthening methods. However, it is true that the research on fatigue performance of concrete structures strengthened by the external prestressing using FRP tendons is rare. Therefore, the purpose of this study is to evaluate the safety and feasibility of the external prestressing method by analyzing the characteristics of the reinforced concrete beam strengthening using FRP tendons under repeated loads. Test variables adopted in this experimental study are the types of external prestressing material (steel or FRP tendon) and the repeated load ranges. The repeated load range have the minimum 50% of yield load of reinforced concrete beam and the maximum 70-85%. The test beams are loaded by 4 point loadings with 3 Hz sine wave. From this experimental study, it is confirmed that the reinforced concrete beams strengthened using FRP tendons have sufficient safety against fatigue, especially in FRP tendon itself, tendon at deviators and tendon at anchorages.

Structural Health Monitoring using Acceleration Response Features of PSC Girder Strengthened with Internal and External Tendons (내부 및 외부 긴장재로 보강된 PSC 거더의 가속도 응답 특성을 이용한 구조건전성 모니터링)

  • Hong, Dong-Soo;Park, Jae-Hyung;Kim, Jeong-Tae;Ryu, Yeon-Sun
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2010.04a
    • /
    • pp.352-355
    • /
    • 2010
  • 본 논문에서는 내부 및 외부 긴장재로 보강된 PSC 거더의 가속도 응답 특성을 이용한 구조건전성 모니터링을 위해 실험 및 수치해석 결과를 비교 분석하는 연구를 수행하였다. 첫 번째로, 내부 및 외부 긴장재로 보강된 모형 PSC 거더를 제작하였다. 두 번째로, 모형 PSC 거더의 형상, 재료 및 경계조건과 긴장재의 배치를 고려하여 초기 유한요소모델을 설계하였다. 세 번째로, 다수의 내부 및 외부 긴장력 조건하의 모형 PSC 거더에 대한 동특성 추출 실험 및 수치해석을 수행하였다. 마지막으로, 실험결과와 수치해석 결과를 비교 분석하여 가속도 응답 특성을 이용한 내부 및 외부 긴장재로 보강된 PSC 거더의 구조건전성 모니터링에 대한 적용성을 검토하였다.

  • PDF

Determination of the Initial Tendon Force using Rating Factor Equation in Composite Girders Strengthened with External Tendons (외부 긴장재로 보강된 강합성보의 내하율 산정식을 이용한 초기 긴장력 결정)

  • Choi, Dong Ho;Chung, Sang Hwan;Yoo, Dong Min
    • Journal of Korean Society of Steel Construction
    • /
    • v.17 no.5 s.78
    • /
    • pp.527-536
    • /
    • 2005
  • A method of reinforcement using external tendons has been found to be one of the effective techniques of reinforcement and its application is increasing. In this paper, the method to calculate the initial tendon force is proposed for the improvement of load-carrying capacity in existing steel-concrete composite bridges. An equation for the increment of tendon force was derived for tendon configurations and live load types, and the effect of reinforcement in a composite beam was numerically studied. The method to calculate the number of tendon and initial tendon force was presented by proposing the new method to calculate the rating factor, which considers the increment of tendon force. The method was shown to be effective for an existing steel-concrete bridge.

Strengthening Design Using Rating Factor Considering Increment of Tendon Force for Two-Span Steel-concrete Composite Bridges Strengthened by Straight External Tendons (직선배치된 외부 긴장재로 보강된 2경간 강합성교의 증가 프리스트레스력을 고려한 내하율 산정식을 이용한 보강설계)

  • Choi, Dong-Ho;Yoo, Hoon;Kim, Yong-Sik;Kim, Sung-Won
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.13 no.2 s.54
    • /
    • pp.153-164
    • /
    • 2009
  • In this paper, a method of increasing in load-carrying capacity is shown in two-span steel-concrete composite bridges strengthened by external tendons. An analytic expression for the increment of tendon force under external loads is derived using virtual work method for straight external tendons and a new rating factor equation is proposed. Considering the initial tendon force and its increment under external loads, an analytic procedure has been developed to calculate the number of tendons and the initial tendon force from the proposed rating factor equation. This method is used to verify a validity and rationality for an existing two-span composite steel-concrete bridge.

Determination of the Initial Tendon Force in Two-span Continuous Steel-Concrete Composite Beam Strengthened with External Tendons (외부 긴장재로 보강된 2경간 연속 강합성보의 초기 긴장력 결정)

  • Choi, Dong Ho;Yoo, Dong Min;Jung, Jae Dong;Kim, Eun Ji
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.10 no.4
    • /
    • pp.145-154
    • /
    • 2006
  • This paper presents a method to enhance the load carrying capacity for a two-span continuous steel-concrete composite beam strengthened with external tendons. The tendon is placed at the bottom of steel beam where the positive bending moment occurs. This results in the reduction of the negative bending moment as well as the positive bending moment. This paper describes the procedure to determine the number of tendon and the initial tendon force for the target rating factor in the rating factor equation. An example beam is given to demonstrate the proposed procedure, and it validity is confirmed.

Evaluation on the Lost Prestressing Force of an External Tendon Using the Combination of FEM and HGA: I. Theory (FEM과 HGA의 조합을 이용한 외부 긴장재의 손실 긴장력 평가: I. 이론)

  • Park, Taehyo;Jang, Hang-Teak;Noh, Myung-Hyun;Park, Kyu-Sik
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.13 no.5 s.57
    • /
    • pp.109-120
    • /
    • 2009
  • This paper introduces a new method to estimate the loss of prestressing force for the externally prestressing tendon. The proposed method that combines of HGA and FEM is able to identify the lost tensile force of a externally prestressed tendon. The identification variables of the proposed method is a exteranlly prestressed tendon of tension, effective nominal diameter, mass per unit length and Rayleigh damping coefficients. First of all, a finite element model system is constructed to consider the effect of damping, and these variables are identified using inverse analysis technique - updating algorithm. Finally, throughout total 3 cases of numerical tests, the numerical propriety of the proposed method is verified. Here, it is seen that the errors in the estimated variables by the proposed method are about 1% except in the case of Rayleigh damping coefficients.

Strengthening Design by External Pre-tensioning and Post-tensioning Methods for Steel-concrete Composite Girders using Rating Factor (내하율을 이용한 강합성보의 외부 프리텐션과 포스트텐션 보강 설계)

  • Choi, Dong-Ho;Yoo, Dong-Min;Jeong, Gu-Sang;Park, Kyung-Boo
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.11 no.5
    • /
    • pp.123-134
    • /
    • 2007
  • A method to determine the initial force of external tendon is proposed to improve the load carrying capacity in existing steel-concrete composite bridges. This method is applied to tensioning external tendons prior to and after concrete replacement for strengthening composite girders. A procedure to determine the number of tendon and initial tendon force is described with the proposed rating factor, which considers the increment of tendon force due to live loads. The method is applied to the improvement of rating factor in an existing composite bridge and its validity is confirmed.

Ultimate Stress of Prestressing CFRP Tendons in PSC Beams Strengthened by External CFRP Prestressing (외부 CFRP 프리스트레싱으로 보강된 PSC 보에서 CFRP 텐던의 극한응력)

  • Park, Sang-Yeol;Kim, Chang-Hoon;Hong, Seong-Yong
    • Journal of the Korea Concrete Institute
    • /
    • v.19 no.6
    • /
    • pp.735-744
    • /
    • 2007
  • This study deals with literature review, developing a predicting equation for the ultimate stress of prestressing (PS) CFRP, and experimental test with the parameters affecting the ultimate stress of prestressing CFRF in prestressed concrete beams strengthened by external prestressing. The ACI (American Concrete Institute) predicting equation for the ultimate stress of unbonded prestressing CFRP is analyzed to develop a new integrated predicting equation. The proposed predicting equation takes rationally the effect of internal PS steel into consideration as a function of prestressing tendon depth to neutral depth ratio. In the experimental study, prestressed concrete beams strengthened using external prestressing CFRP are tested with the test parameters having a large effect on the ultimate stress of prestressing CFRP. The test parameters includes infernal prestressing steel and external prestressing CFRP tendon reinforcement ratios, and span to depth ratio. The test results are analyzed to confirm the rationality and applicability of the proposed equation for predicting the ultimate stress of external prestressing CFRP.

The Experimental Study on the Ultimate Behavior of Steel-Concrete Composite Beams Strengthened with External Tendons (외부긴장재로 보강된 강합성보의 극한거동에 대한 실험적 연구)

  • Choi, Dong-Ho;Na, Ho-Sung;Lee, Jin-Ho
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.12 no.6
    • /
    • pp.63-70
    • /
    • 2008
  • Strengthening method of steel-concrete composite bridges using external tendons has been found as one of the most effective techniques of reinforcement and its application is increasing. In this paper, experimental test was carried out to show the effects on the yield loading and ultimate loading of steel-concrete composite beams strengthened with various configurations of external tendons. Quantitative analysis is carried out to evaluate the effects of experimental variables such as tendon force, deviator, tendon eccentricity and the shape of strands.

A Study on the Reinforcement of Steel Composite Beam Using the External Post-Tensioning Method (외부 후 긴장 공법을 이용한 강합성보의 보강에 관한 연구)

  • Park, Yong-Gul;Park, Young-Hoon;Lee, Seung-Yong
    • Journal of Korean Society of Steel Construction
    • /
    • v.12 no.5 s.48
    • /
    • pp.549-558
    • /
    • 2000
  • In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridges as well as architecture structure. In this study, to investigate the behavior of composite beam in the process of post-tensioning, the amount of prestress force loss, the amount of prestressed compression stress at the lower flange and the behavior of lower flange connected with anchorage are analyzed by comparing the results of finite element analysis with the measured results of installed strain gauges. After finishing the post-tensioning, the strengthening effect of external post-tensioning method is analyzed by static loading test. It is also investigated that the strengthening effect of shear section in the harped external post-tensioning specimens.

  • PDF