• Title, Summary, Keyword: 외부 후긴장

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External Post-tensioning Strengthening of Composite Girder Bridge Using Lateral Distribution of Post-tensioning Force (긴장력 횡분배를 이용한 강합성형교 외부 후 긴장 보강)

  • Park, Young Hoon;Park, Yong Gul
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.6A
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    • pp.587-596
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    • 2009
  • This study analyzes the lateral distribution behavior of external post-tensioning force and evaluates the possibility of strengthening the servicing composite girder bridge by adopting the external post-tensioning force to the parts of the bridge girder. From the results of experiments and analyses, it is founded that the composite girder bridge can be strengthened by applying the external post-tensioning force to the parts of the bridge girder. It is also proved that bracing improve the lateral distribution behavior of post-tensioning force. The lateral distribution behavior of post-tensioning force which influenced by stiffness ratio, girder spacing and span length is changed by the bridge type and the location of tensioned girder. From the results of analyses, set up an equation which can predict the lateral distribution behavior of external post-tensioning force and evaluate the rationality.

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Dynamic Behavior of External Post-tensioned Non-ballast Steel Plate Girder Railway Bridge (외부 후 긴장된 무도상 철도 판형교 동적 거동)

  • Park, Yong Gul;Park, Young Hoon;Choi, Dong Ho
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.3A
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    • pp.315-322
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    • 2008
  • The present study applied the external post tensioning reinforcement method for reinforcing a non-ballast steel plate girder railway bridge, and the effects of the strength of tendons and the level of post-tensioning force on the dynamic behavior are experimented and analyzed. According to the results of this study, the natural frequency was increased by the strength of tendons but it was decreased by the rise of post-tensioning force and as a consequence the introduction of post-tensioning force decreased natural frequency slightly. It was analyzed that further study is need to establish the exact relations between post-tensioning force and natural frequency. In addition, it was found that the dynamic displacement, dynamic bending stress and vertical acceleration were decreased by the external post-tensioning. On the other hand, external post-tensioning increased horizontal acceleration by up to 20%, which was around 70% of vertical acceleration. This needs further study.

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Experimental Study on the Composite Beam Strengthened by External Post Tensioning (외부 후긴장으로 보강한 합성보에 대한 실험적 연구)

  • Kim, Gi Bong;Chung, Young Soo;Choi, Hyok Chu;Kang, Bo Soon
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4
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    • pp.701-708
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    • 1998
  • The application of additional post-tensioning tendons has recently been widely considered and requires very little interference with the existing structure. Several bridges on the national roadway designed as the second class were strengthened by external post-tensioning for the capacity enhancement purpose, but much of that strengthening work was not verified analytically as well as experimentally. This paper examines experimentally the behavior of simple composite steel-concrete beams designed as the second class(DB-18) When they are strengthened with external post-tensioning tendon. Test results show that external post-tensioning increases the ultimate load and the magnitude of tendon force increases the yield load but not the ultimate load.

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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
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    • v.12 no.5
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    • pp.549-558
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    • 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.

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Flexural Behavior Characteristics of Steel I-Beam Strengthened by the Post-tensioning Method on the Field Experiment (현장실험을 통한 외부 후긴장 Steel I-Beam의 휨 거동 특성)

  • Cho, Doo-Yong;Park, Dae-Yul;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.3
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    • pp.151-158
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    • 2002
  • Recently, the externally prestressed unbonded steel I-beam bridges have been increasingly built. The mechanical behavior of prestressed steel I-beams which are with external unbonded tendon is different from that of normal bonded PSC beams in a point of that the slip of tendons at deviators and the change of tendon eccentricity occurs, when external loads are applied in external unbonded steel I-beams. The concept of prestressing steel structures has not been widely considered, in spite of long and successful history of prestressing concrete members. In this study, The field experiment on prestressed steel I-beams has been performed in the various aspects of prestressed I-beam including the tend on type and profile.

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
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    • v.11 no.5
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    • pp.123-134
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    • 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.

A Study on Dynamic Behaviors of Steel Plate Girder bridge with Applying External Post-Tensioning Method (외부 후긴장 공법 적용에 따른 무도상 판형교의 동적거동 분석)

  • Choi, Dong-Ho;Choi, Jung-Youl;Choi, Jun-Hyeok;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.9 no.2
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    • pp.160-168
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    • 2006
  • The major objective of this study is to investigate the effects and application of external post-tensioning method far steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test fur the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about $10{\sim}24%$), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

An Experimental and Analytical study on the Steel Plate Girder Railway bridge in the applying External Post-tensioning Method (강철도교에 대한 외부 후긴장 보강공법의 적용에 관한 실험 및 해석적 연구)

  • Park, Young-Hoon;Cho, Sun-Kyu;Choi, Jung-Youl;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.9 no.2
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    • pp.151-159
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    • 2006
  • It analyzed the mechanical behaviors of non-ballasted railway bridge (steel plate girder type) with ballast reinforced on the finite element analysis, field test and laboratory test far the static and dynamic responses. The major objective of this study is to investigate the effects and application of reinforcement for steel plate girder railway bridge by the external post-tensioning method. The reinforcement of non-ballast railway bridge had obviously stable dynamic behaviors due to the additional dead force which was ballast. But in case of static behaviors, static displacements and stresses had increased nearly the allowable values. Therefore we analyzed the mechanical behaviors of non-ballasted railway bridge with ballast reinforced and external post-tensioning reinforced on the finite element analysis and laboratory test for the static and dynamic behavior. As a result, the reinforcement of ballasted railway bridge the external post-tensioning method are obviously effective for the additional dead force which is ballast. The analytical and experimental study are carried out to investigate the post-tension force decrease bending behavior and deflection in composite bridge for serviceability. The servicing railway bridge with ballast reinforced has need of the reasonable reinforcement measures which could be reducing the effect of additional dead load that degradation phenomenon of structure by an unusual. stresses and a drop durability.