• Title/Summary/Keyword: 프리텐션

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Experimental Study on Structural Behavior of Joints for Precast Concrete Segment (프리캐스트 콘크리트 세그먼트 접합부의 구조거동에 관한 실험적 연구)

  • Lee, Young-Hak;Kim, Min-Sook;Jung, Bo-Na;Kim, Hee-Cheul;Kim, Kwan-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.6
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    • pp.59-65
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    • 2009
  • The use of precast concrete segments facilitates quality control and reduces construction cost and period. However, as a construction method it has limited applicability, for it demonstrates structurally disadvantageous behaviors due to stress concentration and large displacement in the joint of assembled segments. This paper proposes a precast segment joint with improved structural performance, and experimentally assesses the structural performance of the proposed joint in terms of crack and failure modes, deformation, maximum load and displacement ductility. In consideration of constructability and structural performance, this paper suggests different types of joint with shear key, post tension and steel rods as variables, and performs a static loading test on them. The test results show that the performance of SGSP specimens is around 84% that of a monolithic specimen in terms of the maximum load, while their ductility behaviors are better than the monolithic specimen. This result confirms the improved structural performance and applicability of the proposed joint.

A Study on Buckling Analysis of Portable Prestressing Device for Pretensioning PSC girders (프리텐션 방식의 PSC 거더 이동식 제작장치의 좌굴해석 연구)

  • Kim, Jong-Suk;Yoon, Ki-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.1
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    • pp.419-424
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    • 2012
  • This study is a research on the buckling analysis of a portable prestressing device using finite element analysis program, ABAQUS. In order to produce 50m-span PSC girders using pretensioning method, a portable prestressing device has to endure a large jacking force about 10MN. Therefore it shall be safe and stable about the jacking force. In this study, the buckling analysis technique is developed and the buckling analysis of a portable prestressing device is performed using previous studies about the analytical model that the validity of the analytical model was demonstrated by comparing analytical results with experimental results. The stability of the device to produce 10m span PSC girders is investigated.

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.

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.

Field Measurement and Analysis of Post-Tensioned Prestressed Concrete Pavement Behavior under Tensioning (현장실험을 통한 포스트텐션드 프리스트레스트 콘크리트 포장의 긴장 시 거동분석)

  • Park, Hee-Beom;Kim, Seong-Min;Kim, Dong-Ho
    • International Journal of Highway Engineering
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    • v.11 no.1
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    • pp.247-256
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    • 2009
  • This research was conducted to analyze the behavior of PTCP (Post-Tensioned prestressed Concrete Pavement) under tensioning by performing field tests when the experimental PTCP slab was being constructed. The displacements in the slab under the environmental loading and tensioning were measured using temperature measurement sensors and displacement transducers. Tensioning was performed three times and appropriateness of tensioning could be determined by investigating the relationship between temperature and displacement, behavior of transverse crack, and daily change in displacement. The results of this study showed that under the first tensioning at very early age, large displacements were observed only near the joints because of the friction between slab and underlying layer and concrete inelasticity. Under consecutive tensioning, displacements were clearly observed all over the slab, but still affected by the friction. In addition, appropriate tensioning ensured the one-slab behavior of the PTCP slab even though cracks existed.

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Investigations of Application of Anchor Type Nail Using Experiments and Numerical Analysis (모형실험 및 수치해석을 이용한 앵커형 네일의 적용성 검토)

  • Kim, Donggun;Jeong, Gilsu;Jo, Kwangjun;Yoo, Namjae;Um, Jaekyung
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.11
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    • pp.19-26
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    • 2012
  • In the present study, anchor type nail with PC-strand which can add up the pre-stress at the nailing to increase the resistance and shear stress in the whole ground has been investigated. Load-displacement and wall displacement have been analyzed by experimental model and numerical analysis of anchor type nail, nailing, and non-nailing to examine the behavior of anchor type nail. From the experimental results, it was found that horizontal displacement is considerably decreased according to increasing the load in case of anchor type nail added pre-tension. Especially, it was observed that resistance of displacement at the upper wall is increased. The results of numerical analysis show the same results of experimental results.

An Experimental Study on Transfer Length of Domestic CFRP Tendon (국내 CFRP 긴장재의 전달길이에 관한 실험적 연구)

  • Jung, Woo-Tai;Park, Young-Hwan
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.303-310
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    • 2009
  • CFRP(carbon fiber reinforced polymer) tendons can be used as an alternative to solve the corrosion problem of steel tendons. Material properties of CFRP tendons such as bond strength, transfer length, and development length should be determined in order to apply to concrete structures. First of all, in case of application for pretension concrete members with CFRP tendons, transfer length is an important factor. A total of 9 beams have been cast to determine transfer length and development length of domestic CFRP tendon in this paper. Test results revealed that transfer length of the prestressing 25% and 50% are 34D, 55D respectively. Also, transfer length has increased as the prestressing force has increased. A change was observed in transfer length of developed CFRP tendon after 9 weeks. ${\alpha}_t$ of developed CFRP tendon was 2.3 similar to the steel strand.

Experimental Study on Segregated Layers of Materials and Compressive Strength of Concrete for Pretensioned Spun High Strength Concrete Pile (PHC 파일의 압축강도와 재료분리층에 대한 실험연구)

  • 이성로;강성수;유성원
    • Journal of the Korea Concrete Institute
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    • v.13 no.1
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    • pp.16-22
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    • 2001
  • Pretensioned spun high strength concrete (PHC) pile has to be quality-controlled and provided an adequate concrete cover to assure high load carrying capacity, impact resistance, economy, and durability. During spun pre-casting, the pile section is divided into several segregated layers such as laitance, paste, mortar, and concrete layers. Greater the thickness of segregated layers, more difficult it is to guarantee the capacity and the durability of PHC pile. The experimental study was performed to investigate the effects of centrifugal condition on the segregated layers of materials and the compressive strength of concrete for PHC pile. The considering factors in the test were centrifugal time and magnitude of centrifugal force. These factors have been found to have greater influence on the segregation than the concrete strength. The moderate centrifugal condition has to be considered to maintain quality assurance in the production of PHC pile, especially to provide the adequate concrete cover over its tendons.