• Title/Summary/Keyword: 프리스트레스

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Experimental Study on Static Behavior of Laterally Strengthened Spliced Prestressed Concrete Girder using Bending Moment Connector (휨연결재에 의해 횡방향으로 보강된 분절 프리스트레스트 거더의 정적거동에 관한 실험적 연구)

  • Kim, Jae Heung;Kim, Jang-Ho Jay;Kim, Sung Bae;Yi, Na Hyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.3A
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    • pp.287-295
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    • 2010
  • The main purpose of this study is to investigate the static behavior of spliced prestressed concrete girder with bending moment connector and lateral prestressing. Four (4) spliced girders and one (1) monolithic girder had been fabricated and tested to compare their static behaviors. Same geometry and materials are used to fabricate these spliced and monolithic girders. A monolithic girder and one (1) spliced girder without lateral bending connector are used as control specimens to estimate the performance of three (3) spliced girders with lateral bending connector. Deflections at the middle of girders have been measured for evaluation. Also, strains of the concrete at the middle of span and connection points have been measured. It was found from the result that laterally strengthened spliced girders showed improved ultimate strength but less stiffness compared to the monolithic girder at the ultimate state. Laterally strengthened spliced girder also showed improved strength as well as improved stiffness compared to the spliced girder without lateral strengthening.

Strengthening of Reinforced Concrete Continuous Beams in Flexure by Partial External Unbonded Tendons (철근콘크리트 연속보에서 부분프리스트레스 도입에 의한 휨보강 효과)

  • Yun, Hyun-Do;Yang, Il-Seung;Lim, Jea-Hyung;Moon, Jeong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.1
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    • pp.165-172
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    • 2006
  • A variety of techniques for strengthening have been developed, including pate bonding, external prestressing and overslabbing. Expecially, a strengthening technique for reinforced concrete beams using external unbonded reinforcement offers advantages in speed and simplicity of installation. 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. Results of 2 physical tests (external Post-tension and out-cable system specimen) on strengthened reinforced concrete continuous beams are reported and compared. It is shown that the out-cable system can provide strength enhancement.

Investigation of Stress Changes in Concrete and Strands according to Cutting Order of the Strands in Pre-tensioned Concrete Slab (프리텐션 슬래브 구조에서 긴장강선 용접절단순서에 따른 긴장재 및 콘크리트의 응력변화 고찰)

  • Moon, Do-Young;Kim, Jang-Ho;Kim, Gyu-Seon;Yun, Man-Geun;Zi, Goang-Seup
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.419-429
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    • 2009
  • This study focuses on the effect of the cutting order of prestressing strands on the strain change in the strands and on the state of stress of concrete, experimentally and numerically. In the experiment, strain of strands and of transversal reinforcement were measured for three different cutting orders during detensioning process by using flame-cutting procedure. The experimental results were compared with those obtained from the FE analysis. As a results of the experiment, it is confirmed that the cutting order of prestressing strands affected on the strain of strands as well as of transversal reinforcement. The FE analysis gave similar results to those obtained from the experiment. Therefore, the cutting order should be chosen appropriately to when the strands get detensioned.

Evaluation of Dynamic Stability for Structural Bar Reinforced Precast and Prestressed Retaining Wall for Moving Train Load (이동열차하중에 대한 강봉으로 보강된 프리캐스트 프리스트레스트 옹벽의 동적 안정성 평가)

  • Lee, Il Wha;Um, Ju Hwan;Lee, Kang Myung;Keum, Chang Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.190-198
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    • 2011
  • The precast production has many advantages by fast construction period, labor-saving and high quality. In recent years, the application of the precast product has been increased in the earth retaining wall field. This paper presents the results of the numerical analysis that was carried out to evaluate the dynamic stability of precast and prestressed earth retaining wall under moving train load. The two-dimensional FEM analysis was used to the numerical analyses. The train load to act on trackbed is combined by the real measured roughness phase angle and quasi-static load. The dynamic stability is analysed by the displacement, acceleration and stress under moving train load at each specified location. The results of the analysis show that the precast and prestressed retaining wall has very stable capability for the railway.