• Title/Summary/Keyword: Continuous tendon

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An Experimental Study for the Application of Steel Anchorage Zone in Steel-Confined Prestressed Concrete Girder (강재로 구속된 프리스트레스트 콘크리트 합성거더의 강재 정착부 적용을 위한 실험적 고찰)

  • Kim, Jung-Ho;Lee, Sang-Yoon;Hwang, Yoon-Gook;Park, Kyung-Hoon;Oh, Chang-Yeol
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.455-458
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    • 2005
  • The Steel-Confined Prestressed Concrete Girder(SCP Girder) has been developed, which maximizes structural advantages of components (concrete, steel plate and tendon) and can be used to construct the middle or long span bridge with low-height girder. And recently, a continuous beam type of SCP Girder has been being developed to decrease size and self weight of girder in comparison with a simply-supported type. In this study, as part of developing the continuous beam type of SCP Girder, a new type of anchorage zone is proposed in order to address tendons effectively and decrease section size of SCP Girder efficiently. And also, the experimental test was carried out using a real scale specimen to examine the behavior of proposed anchorage zone.

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An Experimental Study on Flexural Behavior of Continuous Prestressed Steel I-Girder with Section Increasement at Internal Supports (지점부 단면형고 확대를 도입한 연속 프리스트레스트 Steel I-Girder의 휨거동에 관한 실험적 연구)

  • Kim, Kyung-Min;Hong, Sung-Nam;Yang, Dong-Suk;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.6
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    • pp.143-153
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    • 2006
  • The paper presents the results of a study on improvement in flexure capacities of continuous prestressed steel I-girder with section increasement at internal supports. After tensioning, the field experiment on prestressed steel I-girder has been performed in the various aspects of prestressed I-girder introducing section increasement at internal supports, tendon profile.

Development of Long-Span Railway Bridges Design Using IPC Girder (IPC 거더를 이용한 장지간 철도교 설계에 관한 연구)

  • Jang, Won-Seok;Park, Jun-Myung;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.4
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    • pp.149-158
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    • 2003
  • It is customary that tendons and sectional dimensions are calibrated and tendon forces are applied at once at the initial stage to keep the subsequent stresses occuring at different loading stages within the allowable stresse in prestressed concrete (PSC) bridge design. However, this traditional tensioning method usually results in a too conservative sectional depth in view of ultimate capacity of a girder. A new design method which can realize the reduction of sectional depth of PSC girder is theoretically suggested in this study. Tendons are tensioned twice at different loading stages: the initial stage and the stage after fresh slab concrete is cast. It can be shown that according to this technique, sectional depth can be significantly reduced and larger span can be realized compared to traditional ones. In this paper, there is an example about the design of bridge by means of new PSC design theory, having a longer span than a existing railway bridge. Also, a new method by continuous tendon profiles is presented to be continuous a IPC bridge.

Structural Behavior of Concrete Girder Continuous Bridges Strengthened with External Tendons Considering the Efficiency at Negative Moment Region (부모멘트부의 효율성을 고려한 외부강선으로 보강된 콘크리트 거더 연속교의 거동)

  • Han, Man-Yop;Cho, Byeong-Du;Jeon, Se-Jin
    • Journal of the Korea Concrete Institute
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    • v.25 no.5
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    • pp.555-564
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    • 2013
  • An effective method was proposed in this study which can improve the strengthening effect of continuous girder bridges by external tendons. The improvement of the proposed strengthening method in comparison with conventional methods was analyzed by applying equivalent load concept. In order to verify the strengthening effect, the enhancement of load-carrying capacity achieved by external prestressing was investigated through the test of continuous beams that were or were not strengthened by the external prestressing. The continuous beams were fabricated by making the deck slab continuous according to general construction practice of an actual concrete girder bridge. The test results showed that the deflections and strains of the strengthened beam were significantly reduced when comparing with those of the non-strengthened beam for the same level of external loads, and the stiffness of the member increased by strengthening. In particular, it was verified that the proposed method can effectively reduce the tensile stresses of the deck caused by negative moment at the intermediate supports of a continuous bridge.

Gait Analysis and Functional Outcomes Following Pan Tarsal Arthrodesis of Tarsal Joint in a Toy Poodle

  • Song, Jaeyong;Kim, Jun-Hyung;Woo, Heung-Myoung;Kang, Byung-Jae
    • Journal of Veterinary Clinics
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    • v.36 no.2
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    • pp.123-125
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    • 2019
  • A 12-year-old castrated Toy Poodle was referred with a continuous non-weight bearing lameness of right hind limb due to a traffic accident 9 years ago. Physical examination and radiographs revealed partial loss of right calcaneal bone, loss of Achilles tendon and disused muscular atrophy. Arthrodesis was performed to preserve the function of the right hind limb. Pan tarsal arthrodesis plate was applied medially with 2.7 mm cortical screws and 2.0 mm cortical screws. During fixation, cancellous bone chip was transplanted into the arthrodesis site. A bone union was confirmed 9 weeks after surgery. Furthermore, on the gait analysis, the weight-bearing of right hind limb was restored to 70% of the opposite hind limb. Arthrodesis can be used to treat more difficult and serious problems affecting the joints. In particular, arthrodesis is indicated in cases such as comminuted intraarticular fractures and irreparable injury of the calcaneal tendon apparatus in the hock joint. In this case, the pan tarsal arthrodesis provided stability to the hock joint and improved the gait by restoring severe chronic damage. In conclusion, we successfully treated a challenging disability of hock joint using pan tarsal arthrodesis to restore the legs that were non-weight bearing due to chronic injury by traffic accident and objectively ascertained the increased weight bearing by gait analysis.

Experimental Study on Post-tensioned 3-Continuous Span Slabs (포스트텐션된 3연속 스팬 슬래브의 실험연구)

  • 임재형;문정호;이리형
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10b
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    • pp.668-673
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    • 1998
  • The specimen of current study has the same type with the 3-span slabs of Burns et al used in the study by Mojtahedi/Gamble, which laid a ground for the revision of the ACI318-77 code to the ACI 318-83 code. But those specimens was failed prematurely before it reached the ultimate strength which the specimen had. The reason is that bonded reinforcements were cut off where there is no need for the flexural reinforcement. As results. the slabs failed ultimately where the reinforcements was cut off. Thus, the tendon stresses of failure may have been much smaller than the values which culd reach if the bonded reinforcements were extended beyond the theoretical cut off points. On the based on the fact mentioned above. the specimens which had the same conditions as the specimens of Burns et al were used in the current study, but in which the reinforcements were distributed in a sequence for the reinforcements not to be cut anywhere in the 3-span. As a results, it was known that the current ACI code, revised by the result of Mojtahedi/Gamble's study, overestimated the effect of span/depth ratio on the members with high span/depth ratio. Thus it was concluded that the effect of span/depth ratio on the ultimate stress of unbonded tendon regulated by the current ACI code must be reconsidered and reevaluated.

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Strengthening of Continuous Composite Grid-girder Bridges by Using the Post-tensioning (후긴장을 이용한 연속 합성 격자형교의 보강 방법에 관한 연구)

  • Back, Dong Hoon;Lee, Woo Hyun;Kim, Ki Bong
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3 s.32
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    • pp.441-455
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    • 1997
  • The need for rehabilitation of the existing bridges is a growing concern in many countries and has been emphasized in various research reports and publications. Many bridges constructed between 1960s and 1970s in Korea were designed for relatively light traffic volumes, speeds and the weight, thus they are inadequate for the present traffic conditions. This together with some design deficiencies, has resulted in deficiencies of various degrees of many bridges. One strengthening method which has significant advantages is the application of external post-tensioning tendons. This paper presents an example of three span continuous composite bridge strenghtened by application of external post-tensioning.

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Detection of Fracture Signals of Low Prestressed Steel Wires in a 10 m PSC Beam by Continuous Acoustic Monitoring Techniques (연속음향감지기법을 이용한 긴장력이 감소된 10 m PSC보의 PS 강선 파단음파 감지)

  • Youn, Seok-Goo;Lee, Chang-No
    • Journal of the Korea Concrete Institute
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    • v.22 no.1
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    • pp.113-122
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    • 2010
  • Corrosion of prestressing tendons and wire fractures in grouted post-tensioned prestressed concrete bridges have been considered as a serious safety problem. In bridge evaluation the condition of prestressing tendons should be inspected, and if corroded tendons are found, the loss of tendon area should be included when we calculate the ultimate strength. In the previous study, it was evaluated that continuous acoustic monitoring techniques could be considered as a reliable non-destructive method for detecting wire fractures of fully grouted post-tensioned prestressing tendons. In the present study, an experimental test was performed for detecting wire fractures of post-tensioned prestressing tendons which are prestressed lower than current design level. A 10 m prestressed concrete beam was fabricated, which included two tendons prestressed 66 percentage and 40 percentage of tensile strength, respectively. The corrosion of two tendons was induced by an accelerated corrosion equipment and the test beam was monitored by using seven acoustic sensors and a continuous acoustic monitoring system. From each prestressing tendon, two acoustic signals of wire fractures were successfully detected and source locations were estimated within 20 mm error. Based on the test results, it is considered that continuous acoustic monitoring techniques can be applied to detect low-prestressed wire fracture in fully grouted post-tensioned prestressed concrete beams.

A Case of Beriberi Because of Continuous Rice-soup Feeding during One and Half Years (지속적인 쌀죽 섭취에 의한 각기병 1례)

  • Yang, Eun Seok;Yoon, Young Hun;Rho, Young Il;Moon, Kyung Rye
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.7 no.2
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    • pp.264-267
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    • 2004
  • Beriberi, which is caused by thiamin deficiency, is a rare disease in recent years. But it has been described in the Eastern literature as far back as the 17th century. Early symptoms are fatigue, apathy, irritability, drowsiness, anorexia, nausea, vomiting and abdominal pain. Signs and symptoms of progression are peripheral neuritis, paresthesia, decreased tendon reflex and congestive heart failure. Thiamin deficiency remains as an important health care issue in many world population, specially in AIDS, pregnancy women and TPN associated patients. The best diagnostic test is assessing clinical response to administration of thiamin. We have experienced a case of Beriberi caused by continuous rice-soup feeding during one and half years in a 7-year-old boy.

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Recent Updates Regarding Outcomes and Complications of Reverse Total Shoulder Arthroplasty

  • Chung, Seok Won
    • Clinics in Shoulder and Elbow
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    • v.20 no.3
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    • pp.172-179
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    • 2017
  • Indications of reverse total shoulder arthroplasty (RTSA) have been consistently extended by technical advancements in reverse arthroplasty prosthesis, continuous development of the implants, accumulated experiences and its successful treatment outcomes; accordingly, its use has rapidly increased. RTSA has been performed for a variety of indications, with variable outcomes depending on the initial diagnosis. However, controversial opinions still exist regarding the design of reverse arthroplasty prosthesis (medialized or lateralized design and the neck-shaft angle of the humeral prosthesis), suture of the subscapularis tendon, use of cement during placement of the humeral prosthesis, and surgical procedures; therefore, these should be investigated so that they can be better understood.