• 콘크리트학회논문집
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• 제11권6호
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• pp.13-24
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• 1999

The external, unbonded prestressed concrete(PSC) members exhibit very different structural behavior from that of internal bonded PSC members because of eccentricity change and slip occurrence during loading process. The purpose of the present study is to propose the ultimate failure stresses of prestressing (PS) steels for those external unbonded PSC members. To this end, a comprehensive analysis has been made using the nonlinear finite element analysis program developed recently for external unbonded PSC members by authors. A series of major influencing variables have been included in the analysis. It was found that the span-depth ratio, neutral axis depth-effective depth ratio, load geometry, amount of ordinary steel, and prestressing steel ration have great influence for the ultimate failue stress of PS steel is preposed and is compared with experimental dat as well as existing formulas for internal unbonded members. The Comparison indicates that the proposed equation agrees relatively well with experimental data and that existing formulas including ACI and AASHTO equations show some discrepancies from experimental ones. The present study allows more realistic analysis and design of prestressed concrete structures with external unbonded tendons.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.93-98
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• 2001

This study is to develop the end anchorage of external steel reinforcement of RC slab bridges. External prestress method using the existing steel is that When the anchorage is installed in slab end, a plenty of anchor bolts were required because the only tangential stress of anchor bolt received a tendon force. Then, for this reason, the wide end anchorage was required and the shape was complicate. But this reinforcement method using method that inserts anchor key at concrete surface cut a groove gets big internal force comparing to the anchorage using existing anchor bolt. Furthermore, the number of anchor bolt for installing apparently will be reduced, and the operation will be convenient because a small anchorage of a simple shape will be received a great tendon force

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1009-1014
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• 2001

This study is to develop the end anchorage of external steel reinforcement of RC slab bridges. External prestress method using the existing steel is that When the anchorage is installed in slab end, a plenty of anchor bolts were required because the only tangential stress of anchor bolt received a tendon force. Then, for this reason, the wide end anchorage was required and the shape was complicate. But this reinforcement method using method that inserts anchor key at concrete surface cut a groove gets big internal force comparing to the anchorage using existing anchor bolt. Furthermore, the number of anchor bolt for installing apparently will be reduced, and the operation will be convenient because a small anchorage of a simple shape will be received a great tendon force.

• 한국강구조학회 논문집
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• 제14권1호
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• pp.79-85
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• 2002

본 연구에서는 기존에 사용된 H-Beam 교량을 편향부와 외부 긴장력을 도입하여 보강효과에 의하여 지간을 증가시킬 수 있고 단면을 축소할 수 있다는 근거를 제시하였고, 유연도법을 이용하여 편향부의 효과에 의한 추가 긴장량을 산정하였다. 또한, 실험변수(긴장량, Tendon의 개수, 편향부의 유 무)에 의해서 표준실험체(기존 H-Beam)와 외부 긴장된 H-Beam 등 5개의 실험체를 제작하여 휨 실험을 실시하여 외부 긴장된 H-Beam의 역학적 거동을 연구하였다. 특히, 보강효과 및 편향부의 효과를 실험적으로 검증하였다.

• Computers and Concrete
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• 제15권1호
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• pp.55-71
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• 2015

This paper presents a novel harmony search (HS)-based data-driven single input rule modules (SIRMs)-connected fuzzy inference system (FIS) for the prediction of stress in externally prestressed tendon. The proposed method attempts to extract causal relationship of a system from an input-output pairs of data even without knowing the complete physical knowledge of the system. The monotonicity property is then exploited as an additional qualitative information to obtain a meaningful SIRMs-connected FIS model. This method is then validated using results from test data of the literature. Several parameters, such as initial tendon depth to beam ratio; deviators spacing to the initial tendon depth ratio; and distance of a concentrated load from the nearest support to the effective beam span are considered. A computer simulation for estimating the stress increase in externally prestressed tendon, ${\Delta}f_{ps}$, is then reported. The contributions of this paper is two folds; (i) it contributes towards a new monotonicity-preserving data-driven FIS model in fuzzy modeling and (ii) it provides a novel solution for estimating the ${\Delta}f_{ps}$ even without a complete physical knowledge of unbonded tendons.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.156-159
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• 2008

This paper introduces a remained tensile force estimation method using SI technique based on evolutionary algorithm for externally prestressed tendon. This paper applies the differential evolutionary scheme to SI technique. A virtual model test using ABAQUS 3 dimensional frame model has been made for this work The virtual model is added to the tensile force(28.5kN). Two set of frequencies are extracted respectively from the virtual test and the self-coding FEM 2 dimension model. The estimating tendon tension for the FEM model is 28.31kN. It is that the error in the tendon tension is 1% through the differential evolutionary algorithm. The errors between virtual model and the self-coding FEM model are assumed as the model error.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.681-684
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• 1999

The development of external prestressing methods has been one of the major trends in the concrete bridge constructions over the past decades. One of the promising methods to enhance the flexural strength of a externally prestressed girder is to place the tendons with large eccentricities. The test results in this study showed that the external prestressing of a composite girder increased the range of the elastic behavior, reduced deflections, increased ultimate strength, and added to the redundancy by providing the multiple stress paths. This study was conducted on the concrete bridges reinforced by the continuous girders and the external prestressing.

• 한국구조물진단유지관리공학회 논문집
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• 제6권3호
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• pp.151-158
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• 2002

외부 후 긴장 공법은 설계에 수반되는 구조해석이 비교적 명확하여 강교량 구조물뿐만 아니라 건축 구조물 등 그 적용범위가 매우 넓다. 본 연구에서는 외부 비부착 강연선 및 강봉을 가진 Steel I-Beam의 휨거동과 보강효과를 연구하기 위하여 우선 합리적인 이론해를 제시하고, 긴장력 도입 후 정적 휨 재하 실험을 수행하여 긴장력 도입 정도에 따른 휨 보강정도를 분석하였다. 또한, 강봉을 사용한 경우와 강연선을 사용한 경우로 시험체를 분류하여, 긴장재 종류에 따른 휨거동 특성과 보강효과를 비교 분석하였다. 아울러 강봉의 개수와 편향부 유.무에 따른 Beam의 휨거동 특성과 부재의 처짐의 증가에 따른 Tendon 위치의 편심량 값이 변화하고, 그에 따른 프리스트레스트 I-Beam의 휨 거동에 미치는 영향을 규명하였다.

• 한국임상수의학회지
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• 제39권6호
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• pp.378-383
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• 2022

A 3-year-old, 24-kg intact female Border Collie was referred for a toe-touch weight-bearing stance, intermittent weight-bearing lameness, and moderate pain reaction of the right forelimb on physical examination and right humerus olecranon avulsion fracture on diagnostic imaging examination. Surgical repair was performed using tension band wiring to re-attach the triceps tendon and distal olecranon. Migration of the distal olecranon fragment was observed due to comminuted fracture of the fragment 5-days after surgery, and revision surgery was performed. The tension-relieving sutures were passed through the pre-drilled hole in the olecranon, and the polyester mesh was augmented to the suture region, covering the triceps tendon and olecranon drilling hole using the Krackow suture pattern. The elbow joint was immobilized using a type IA transarticular external fixator, which was removed 8 weeks after surgery. Fourteen weeks after surgery, no lameness was observed on gait evaluation. At follow-up after 7 months, the distal olecranon fragment had stabilized, and no lameness was observed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.141-142
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• 2009

본 논문은 외부긴장재의 고유진동수를 사용한 유효긴장력의 추정결과를 기술하였다. 외부긴장재는 PSC 교량의 중요부재인 긴장재에 대한 높은 접근성을 가지고 있다. 1개 경간에 위치한 6개의 외부긴장재를 임팩트 햄머를 사용하여 가진하였으며, 이에 따른 진동을 가속도계를 사용하여 측정하였다. 유효긴장력은 측정된 고유진동수를 이상화된 stiff string model에 적용하여 추정하였다.