• Title/Summary/Keyword: 아치

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Optimum Design of a Lightweight Mirror (경량화 반사경의 최적설계)

  • 박강수;박현철;조지현;윤성기;이준호
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.96-97
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    • 2003
  • 인공위성 카메라에 장착되는 반사경의 경우 광학적 상의 열화에 영향을 미치는 자체 변형을 최소화하기 위해 경량화와 함께 높은 강성이 유지되도록 설계하여야 한다. 이를 위하여 일반적으로 반사경의 하판의 형상을 벌집구조로 만들거나 단일아치나 이중아치로 만드는 경우가 많다. 예로 벌집구조를 가진 경량화 반사경의 형상을 그림 1에, 경량화 형상을 정의하기 위한 기하학적 변수를 그림 2에 나타내었다. 여러 가지 반사경 형상에 따른 광학적 성능비교가 Valent와 Vukobratovich에 의해 시도되었다. (중략)

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Full-Scale Test on Precast Concrete Arch Bridge with Reinforced Joint and Backfill (보강된 이음부와 뒤채움을 적용한 조립식 프리캐스트 콘크리트 아치교량의 실물모형실험)

  • Chung, Chulhun;Joo, Sanghoon;Choi, Dongchan;Lee, Jongyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.2
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    • pp.389-402
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    • 2014
  • In this paper, the load test of full-scale precast concrete arch bridges considering reinforced joint and backfill was conducted. It is an improved method that the reinforced joint enhanced the structural performance of conventional masonry arch system which was proposed by previous researchers. The models of full-scale test are $10m(span){\times}3m$ (rise) and $10m(span){\times}2m$ (rise), which are 2 meters in width. The critical load position was shown at a third-span from the results of the pre-analysis. Based on the this results, the positions of load, measuring items and points were determined in experiments. As a result, the maximum load capacity of the specimen $10m{\times}2m$, a relatively small rise to span ratio (compared to the specimen $10m{\times}3m$), was higher than the specimen $10m{\times}3m$. It was evaluated that all the specimens have sufficient structural performance on the design load.

A Study on the Effect of Carrying Vertical Loads Over Embankment Piles (성토지지말뚝의 연직하중 분담효과에 관한 연구)

  • 홍원표;이광우
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.285-294
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    • 2002
  • Embankment Piles, which is subjected to damage due to lateral movement of soft ground, can be classified into pile slab, cap beam pile, and isolated cap pile according to the installation pattern of pile cap. In the cap beam pile and the isolated cap pile method, the soil arch is developed by the different stiffness between pile and soil, and most embankment loads are transferred into embankment piles through soil arch. In these two methods, the difference of soil arch is that the soil arch of the cap beam pile method develops like the arch from of tunnel between cap beams and the soil arch of the isolated cap pile method develops like dome between isolated caps. Therefore, theoretical analysis methods on soil arching effect of the cap beam pile and the isolated cap pile method were respectively proposed according to their own arch form considering the limiting equilibrium of stresses in a crown of soil arch. And a series of model tests were performed both to investigate the load transfer by soil arching in fills above embankment piles and to verify the reliability of the theoretical analysis.

Structural Performance of Precast Concrete Arch with Reinforced Joint (보강된 이음부를 가진 조립식 프리캐스트 콘크리트 아치의 구조성능)

  • Chung, Chulhun;Joo, Sanghoon;Choi, Dongchan;Lee, Jongyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.1
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    • pp.29-47
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    • 2014
  • The masonry stone arch bridge, due to its superior durability and aesthetics, has been one of the oldest and popular types of short span bridges. In Europe, this type of bridges have been continuously constructed, and numerous related researches have been conducted until recently. However, there are few construction cases in Korea since the economic efficiency and the construction effectiveness is not contentable. Therefore, this study proposed the reinforced joint to improve structural performance of the conventional arch systems which is proposed by previous researchers. The structural performance of the proposed reinforced joint, which consists of the transverse loop joint and the longitudinal reinforcement, is validated by experimental test of an arch bridge which is constructed using precast concrete segments. Based on this results of the experimental test, it is concluded that the strength of arch bridges can be enhanced by applying the proposed reinforced joints since the reinforced joint restrains hinge behavior and relative displacement between segments with a little reinforcement.

Estimation of Modal Parameters for Plastic Film-Covered Greenhouse Arches (비닐하우스 아치구조의 모달계수 산정)

  • Cho, Soon-Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.2
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    • pp.67-74
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    • 2010
  • To a series of vibration records obtained from experimental modal testing using a fixed hammer and roving accelerometers for greenhouse arch structures, modal parameters such as natural frequencies, damping ratios and mode shapes are extracted by applying the two most advanced system identification methods in the frequency-domain up to now, so-called PolyMAX and FDD. The former involves both input and output data, while the latter utilizes only the output data. The possibility of determining the static buckling load, detecting damages, etc., for very slender steel-pipe arches by means of a non-destructive testing method based on vibration measurements is primarily investigated. The extracted modal parameters generally correlated well with those obtained using finite element analysis, demonstrating promising results for further on-going research.

Shear Compatibility Condition with Arch Action in Simply Supported RC Beam (단순지지된 RC보에서의 아치효과를 고려한 전단변형적합조건)

  • Lee, Seong-Chul;Cho, Jae-Yeol;Kim, Woo;Park, Byung-Sun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.847-850
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    • 2008
  • In simply supported concrete beams with concentrated load, there is arch action that the internal lever arm length varies through shear span. Recently shear analysis model considering this effect has been developed, but the analysis algorithm is so complicated. Moreover, the variation of internal lever arm length is not considered on the shear compatibility condition. In this study, the shear analysis model is developed more simply and the variation of internal lever arm length is considered on the shear compatibility condition. From these modifications, an actual shear behavior of RC beams subjected to concentrated load could be expected from the results of the proposed analysis model.

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