• Title/Summary/Keyword: 비부착 긴장재

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Flexural behavior of RC beams with unbonded prestressing CFRP laminates (비부착 탄소섬유판 긴장재를 갖는 철근 콘크리트 보의 휨거동)

  • Park, Jong-Sup;Park, Young-Hwan;Jung, Woo-Tai
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.258-261
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    • 2006
  • This study investigates the flexural behavior and strengthening performance of RC beams with unbonded prestressing CFRP laminates through static bending tests. The aluminum anchorage system has been developed in tins study and successfully applied to the test specimens. The prestressing level of CFRP laminatehas was 0 %, 20 %, 30% and 50 % of its tensile strength. Experimental results revealed that RC beams with unbonded prestressing CFRP laminates showed increased crack load and yield load according to the level of prestress. It has also been observed that the length of the CFRP laminates does not have significant effect on the maximum load.

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Evaluation of Ultimate Strength Design Equations for Stress Calculation of Unbonded Tendons (비부착 긴장재의 응력산정을 위한 극한강도 설계식의 평가)

  • 임재형;문정호;이리형
    • Journal of the Korea Concrete Institute
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    • v.11 no.3
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    • pp.113-122
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    • 1999
  • The present study is to investigate the possibility of overestimation or underestimation when the ACI Code equations are used to evaluate the unbonded tendon stress. An experimental program was planned with 6 beams which divided into two groups. Each group consisted of 3 beams to check the possibility of overestimation or underestimation of unbonded tendon stress. The experimental results were also compared with various design equations including the one proposed by Moon and Lim. It was proven that the ACI Code equations may overestimate or underestimate the unbonded tendon stress in certain cases.

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.

Evaluation of Characteristics of Ground Anchor Using Large Scale Laboratory Test (실규모 실험을 이용한 그라운드 앵커의 거동 특성 평가)

  • Sangrae Lee;Seunghwan Seol
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.11
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    • pp.19-24
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    • 2023
  • Ground anchor has been widely used specially for maintaining stability on reinforced cut slope in expressway. While the durability of the ground anchors should be ensured over the service life. However, the long-term loss of tensile force has occurred in most of field-installed anchors. Main causes are not clearly identified and very few studies have been made for analyzing long-term behavior of ground anchor in slopes. In this study, full-scale model tests and long-term measurements were made to obtain the load-displacement data and identified the causes of the long-term behaviors of ground anchor. As a result, the bond strength decreases exponentially with increasing water-binder ratio. Especially, groundwater is the most influencing factor to the bond strength. In the long-term behavior, the load decreases sharply until the initial settlement stabilized, and thereafter the tension force decreases constantly.

Crack Width Prediction in Concrete Bridges Considering Bond Resistances affected by Corrosion (부식에 의한 부착저항감소를 고려한 콘크리트 교량의 균열폭 예측)

  • Cho, Tae-Jun;Cho, Hyo-Nam;Park, Mi-Yun
    • Journal of the Korea Concrete Institute
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    • v.18 no.4 s.94
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    • pp.543-552
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    • 2006
  • The current design for crack width control in concrete bridges is incomplete in analytical models. As one of the important serviceability limit states, the crack width be considered with the quantitative prediction of the initiation and propagation of corrosion and corrosion-induced cracking. A serviceability limit state of cracking can be affected by the combined effects of bond, slip, cracking, and corrosion of the reinforcing elements. Considering life span of concrete bridges, an improved prediction of crack width affected by time-dependent general corrosion has been proposed for the crack control design. The developed corrosion models and crack width prediction equation can be used for the design and the maintenance of prestressed and non-prestressed reinforcements by varying time, w/c, cover depth, and geometries of the sections. It can also be used as the rational criteria for the maintenance of existing concrete bridges and the prediction of remaining life of concrete structures.

A Case Study of PC-Culvert Construction with Foundation Plate (기초판 보강형 PC 암거의 시공사례 연구)

  • You, Jun;Choi, Chang-Ho
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.2
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    • pp.13-19
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    • 2011
  • Precast culvert system is generally constructed with a series of process such as excavation, ground mitigation, placement of culverts, anti-leakage packing between adjacent culverts, post-tensioning for PS strands and backfilling. In this process inappropriate ground mitigation often causes differential settlement and, correspondingly, makes water-leakage to be occurred between adjacent boxes. This study was performed to understand the behavioral characteristics of recently proposed precast foundation plate to support precast culvert system through on-site pilot construction. The gap between two adjacent culverts, increment of earth pressure at the bottom of culvert, vertical settlement of top of the culverts were monitored using various sensors. The monitoring results showed that the proposed foundation plate provides better culvert system in the points of less gap development, earth pressure and settlement at the adjacent of two culverts.