• Title/Summary/Keyword: curved concrete

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Evaluation of Shape Deviation in Phase Change Material Molds Subjected to Hydration Heat During Ultra-High Performance Concrete Free-form Panel Fabrication (UHPC 비정형 패널 제작 시 수화열에 의한 PCM 거푸집의 형상오차 분석)

  • Kim, Hong-Yeon;Cha, Jae-Hyeok;Youn, Jong-Young;Kim, Sung-Jin;Lee, Donghoon
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.3
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    • pp.251-260
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    • 2023
  • The construction of free-form structures with intricate curved exteriors necessitates the use of bespoke molds. To fulfill this requirement, a blend of Phase Change Material(PCM) and Ultra-High Performance Concrete(UHPC) is utilized. PCM endows the solution with recyclability, while UHPC facilitates the effortless execution of curvature in the mold fabrication process. However, it's worth mentioning that the melting point of PCM hovers around 58-64℃, and the heat emanating from UHPC's hydration process can potentially jeopardize the integrity of the PCM mold. Hence, experimental validation of the mold shape is a prerequisite. In the conducted experiment, UHPC was poured into two distinct mold types: one that incorporated a 3mm silicone sheet mounted on the fabricated PCM mold(Panel A), and the other devoid of the silicone sheet(Panel B). The experimental outcomes revealed that Panel A possessed a thickness of 3.793mm, while Panel B exhibited a thickness of 5.72mm. This suggests that the mold lacking the silicone sheet(Panel B) was more susceptible to the thermal effects of hydration. These investigations furnish invaluable fundamental data for the manufacturing of ultra-high strength irregular panels and PCM molds. They contribute substantially to the enrichment of comprehension and application of these materials within the realm of construction.

Effect of Crack Control Strips at Opening Corners on the Strength and Crack Propagation of Downsized Reinforced Concrete Walls (축소 철근콘크리트 벽체의 내력과 균열진전에 대한 개구부모서리 균열제어 띠의 영향)

  • Wang Hye-Rin;Yang Keun-Hyeok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.4
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    • pp.40-47
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    • 2022
  • The present study aimed to examine the effectiveness of different techniques for controlling the diagonal cracks at the corners of openings on the strength, deformation, and crack propagation in reinforced concrete walls. The crack control strip proposed in this study, the conventional diagonal steel reinforcing bars, and stress-dispersion curved plates were investigated for controlling the diagonal cracks at the opening corners. An additional crack self-healing function was also considered for the crack control strip. To evaluate the volume change ratio and crack width propagation around the opening, downsized wall specimens with a opening were tested under the diagonal shear force at the opening corner. Test result showed that the proposed crack control strip was more effective in reducing the volume change and controlling the crack width around the opening when compared to the conventional previous methods. The crack control strip with crack healing feature displayed the superior performance in improving the strength of the wall and reducing the crack width while healing cracks occurred in the previous tests.

A Study on the Damages of Head Works by the Storm Flood in the Area of Cheong Ju and Boeun -Emphasis onFactors Influenced on the Disasters and their Countermeasures- (淸州 및 報恩地方의 頭首工洪水災害에 關한 調査硏究(II) -災害原因 및 對策方案을 中心으로-)

  • Nam, Seong-Woo;Kim, Choul-Kee
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.24 no.2
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    • pp.49-55
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    • 1982
  • The purpose of this study is to classify the factors influenced on the damages of head works suffered from the storm flood occurred on July 22 1980 in both Musim and Bochong rivers and to find out an integral counter measures against the causes influenced on the disaster of head works in the engineering aspect of planning, design, construction and maintenance. In this survey, number of samples was taken 25 head Works, and the counter measures against the causes of their disasters summarized was as follows, 1. In the aspect of planning a. As the flood water level after the establishment of head works is more increased than the level before setting of head works owing to having more gentle slope of river bed between the head works than nature slope of river bed. Number of head works should be reduced for the appropriate annexation of them b. In the place where head works is established on the curved point of levee, the destruction of levee becomes severe by the strong deflective current. Therefore the setting of head works on the curved point should be kept off as long as possible and in case of unavoidable circumstances the construction method such as reinforced concrete wall or stone wall filed with concrete and anchored bank revetments should be considered. 2. In the aspect of design a. As scoring phenomena at up stream is serious around the weir Where the concentration of strong current is present in such a place, up stream apron having impermeability should be designed to resist and prevent scoring. b. As the length of apron and protected bed is too short to prevent scoring as down stream bed, the design length should be taken somewhat more than the calculated value, but in the case the calculated length becomes too long to be profitable, a device of water cushion should be considered. c. The structure of protected river bed should be improved to make stone mesh bags fixed to apron and to have vinyl mattress laid on river bed together with the improvement for increasing the stability of stone mesh bags and preventing the sucked sand from the river bed. d. As the shortage of cut-off length, especialy in case of the cutoffs conneting both shore sides of river makes the cause of destruction of embankment and weir body, the culculation of cut-off length should be taken enough length based on seepage length. 3. In the aspect of design and constructions a. The overturing destruction of weir by piping action was based on the jet water through cracks at the construction and expansion joints. therefore the expansion joint should be designed and constructed with the insertion of water proof plate and asphalt filling, and the construction joint, with concaved shape structure and steel reinforcement. b. As the wrong design and construction of the weep holes on apron will cause water piping and weir destruction, the design and construction of filter based on the rule of filter should be kept for weep holes. c. The wrong design and construction of bank revetment caused the severe destruction of levee and weir body resulting from scoring and impulse by strong current and formation of water route behind the revetment. Therefore bank revetment should be designod and constructed with stone wall filled with concrete and anchored, or reinforced concrete wall to prevent the formation of water flow route behind the wall and to resist against the scoring and impulse of strong stream. 4. In the aspect of maintenance When the damaged parts occurred at head works the authorities and farmers concerned should find and mend them as soon as possible with mutual cooperation, and on the other hand public citizen should be guided for good use of public property.

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Torsional Behavior of Hybrid Truss Bridge according to Connection Systems (복합트러스교의 격점구조별 비틀림 거동)

  • Jung, Kwang-Hoe;Lee, Sang-Hyu;Yi, Jong-Won;Choi, Ji-Hun;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.25 no.1
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    • pp.63-72
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    • 2013
  • HTB (hybrid truss bridge) steel truss webs instead of concrete webs in prestressed box girder bridges has been widely used in, because of its structural benefit such as relatively less self-weight and good aesthetics due to open web structure. Since the core technology of this bridge is the connection system between concrete slabs and steel truss members, several connection systems were proposed and experimentally evaluated. Also, the selected joint system was applied to the real bride design and construction. The researches were performed on the connection system, since it can affect the global behavior of this bridge such as flexural and fatigue behaviors as well as the local behavior around the connection region. The evaluation study showned that HTB applied to a curved bridge or a eccentric loading bridge, characteristic has a weak torsional capacity compared to an ordinary PSC box girder bridges due to the open structure of HTB. In this study, three box shaped hybrid truss specimens were made and the torsional test and evaluation for them were performed in order to find out the torsional behavior of HTB according to the connection system.

Evaluation of Plastic Accumulative Settlement of Embedded Rail Track by Real-scale Repetitive Load Tests (실대형 반복재하시험을 통한 매립형궤도 소성누적침하 평가)

  • Lee, Su-Hyung;Kang, Yun-Suk;Oh, Sang-Ho;Park, Jeung-Geun
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.406-411
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    • 2011
  • An active application of tram is being expected in Korea in the near future. For the tram operation in urban area, the embedded rail tracks where rails are completely embedded with pavements is required. When the embedded rail track is constructed on fine-grained subgrade soil, excessive cumulative plastic settlements due to repetitive tram road may occur. In this study, repetitive load tests were carried out to evaluate the accumulative plastic settlements of subgrade soils underneath embedded rail tracks. Two real-scale track specimens of 5 m lengths were constructed considering the maximum cant of a curved line. Repetitive tram loads of three million times were applied to the tracks in 5 Hz frequency. The accumulating patterns of plastic settlements were analyzed. Tram load distributing effects of the concrete slabs were also evaluated using the measured data of earth pressures cells that were installed underneath track. Also the measured settlements were compared with the estimated settlements calculated from an existing experimental equations, and its validity is discussed.

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A Transcultural Reflection on Anglo-Chinese Gardens in the 18th Century (18세기 '중국풍 정원(Anglo-Chinese garden)'의 문화전이에 관하여)

  • Kim, Daesin
    • The Journal of Art Theory & Practice
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    • no.16
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    • pp.201-224
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    • 2013
  • The tradition of the representative art style in the Sinosphere, Shanshui hua, expresses the traditional representation of the harmony and principle of the universe. This tradition is reflected in the Chinese garden. These Chinese gardens were precisely the three-dimension representations of Shanshui hua, a visual form of abstract expression of the oriental philosophical thinking. This research determines and draws attention to the vestiges of the reflection of Shanshui hua in the European gardens through visual art and culture. It will also approach the two subjects, Shanshui hua and garden, from a transcultural view to integrally analyze visual art. The appearance of Anglo-Chinese gardens, reflecting Shanshui hua, foreshowed a big change in traditional European gardens. This is a concrete example of the transcultural phenomenon. This has formed the typical naturally curved English gardens in the gardening history. This also divided these English gardens completely from the symmetrical, geometrical French gardens. This study considers the influence and the reverberation of Shanshui hua reflected on European gardens in the European culture. The cultural exchange of European and Chinese styles in the 18th century left an impact on the European gardening style history. Finally, this study analyzes the origin of these Anglo-Chinese gardens and its content to approach it with a transcultural view as a research methodology.

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Nonlinear dynamic analysis of RC frames using cyclic moment-curvature relation

  • Kwak, Hyo-Gyoung;Kim, Sun-Pil;Kim, Ji-Eun
    • Structural Engineering and Mechanics
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    • v.17 no.3_4
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    • pp.357-378
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    • 2004
  • Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. Unlike previous analytical moment-curvature relations which take into account the flexural deformation only with the perfect-bond assumption, by introducing an equivalent flexural stiffness, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end, which accounts for more than 50% of the total deformation. The advantage of the proposed relation, compared with both the layered section approach and the multi-component model, may be the ease of its application to a complex structure composed of many elements and on the reduction in calculation time and memory space. Describing the structural response more exactly becomes possible through the use of curved unloading and reloading branches inferred from the stress-strain relation of steel and consideration of the pinching effect caused by axial force. Finally, the applicability of the proposed model to the nonlinear dynamic analysis of RC structures is established through correlation studies between analytical and experimental results.

Applicability Evaluation of PSC-U Type Girder and Precast Deck to the Vertical Curves in Urban Maglev Train Route (도심형 자기부상열차 선로 종곡선 구간에서의 PSC-U 형 거더와 프리캐스트 바닥판 적용성 평가)

  • Jin, Byeong-Moo;Kim, In-Gyu;Kim, Young-Jin;Lee, Yun-Seok;Ma, Hyang-Wook;Oh, Hyun-Chul
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.24-30
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    • 2008
  • One of the characteristics of the Maglev Train is the prominent capability of upgoing. Maglev train with the aim of longitudinal slope 7/100 is under development by the Center for Urban Maglev Program in Korea. To realize these slope, vertical curves must be inserted before and after the slope. The inserted curve has the radius of 3,000m generally. The insertion of these vertical curve results in the additional differences between the girder upper face and the guide rail, and the alignments are controlled by cast in place concrete at present. In this study, for longitudinal curved route with longitudinal slope 6/100, the applicability of PSC-U type girder and precast deck was evaluated for the span length 25m, 30m and vertical curve radii with 3,000m and 1,500m with respect to longitudinal slope 6/100.

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A Design Research for the Practical Use of College Women′s Casual Hanbok (여대생들의 생활한복 실용화를 위한 디자인 연구)

  • 김장향
    • Journal of the Korea Fashion and Costume Design Association
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    • v.2 no.2
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    • pp.55-79
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    • 2000
  • This study is the design research for the practical use of Casual Hanbok. The conclusion of basic research for Casual Hanbok design reads as follows. Today's college women are fairly positive to the practical use of Casual Hanbok. Especially, they are strongly interested in the new design and have the active intention to wear it on actually. The concrete design of every parts of Casual Hanbok which is wanted by college women is as follows. Firstly, college women like well matched two-piece dress style in colors. And they want to decide the coloration independently than to follow the traditional coloration passively. Secondly, according to the design of jacket, sometimes they like the presence of a collar, a collar strip, a gore etc. and at other times they like absence of them. Thirdly, the side line of jacket they like and the seam line of sleeve they like is smoothly curved one and the adjusting means they like is a fancy button. Fourthly, the length of jacket they like reaches to their waist and the width of an armhole they like must be convenient for moving of arm. Fifthly, one out of two college women likes mixed spinning fabrics as material for jacket, skirt, pants. In the other hand, one out of five college women likes cotton. Sixthly, the skirt style they like is A ­line one having from two to four gathers on the waist and the length of skirt they like reaches to their ankle or calf of the leg. Seventhly, the pants style they like is the western style but the hem line of pants is the korean traditional pants style.

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Analysis of the Koreanity Expression Properties found in the Modern Commercial Spaces from a Design Coordination Viewpoint (현대 상업공간에 표현된 디자인코디네이션 관점의 한국성 특성 분석)

  • Yim, Sun-Hee;Park, Young-Soon;Jung, Eui-Chul
    • Korean Institute of Interior Design Journal
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    • v.21 no.5
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    • pp.135-144
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    • 2012
  • Since Seoul was selected as the world design capital at the end of 2007, the endeavors to modernize the Korean unique beauty is becoming more tangible. Especially, the commercial spaces to be used by the general public and tourists have the value for study in the respect that such spaces for the national iconic images and have a large and far-reaching effect to transmit the national identity. Therefore, this study analyzed the design coordination properties in the Koreanity expression found in the modern commercial spaces. the foundation for the analysis was based on Leonard Koren's work on the arrrangement rhetoric theory, 'Arranging things(2003), and the contents of Korean expression were reviewed with professional jounals. the results are as follows: First, the design coordination properties in the Koreanity expression shown in modern commercial spaces are black-white contrast, natural materials, curved shapes, brevity, and simple beauty. Especially, some elements such as wood, traditional Korean papers, stones, mid-to-low chroma natural colors, checked patterns, and crazy patterns are used with overlapping and it is viewed that it is necessay to more aggressively seek for the disappeared traditional elements in the Korean modeling properties. Second, the concrete images of Korean expressions could be summarized as four adjective image groups, Natural, Subtitle, Gentle and Magnificent.

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