• Title/Summary/Keyword: Floating slab

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Semi-active control of elastically supported floating slab vibration excited by the moving train mass (열차 운행 중 발생하는 탄성지지 슬라브 진동의 반능동 제어)

  • Lee, Gyu-Seop;Jang, Seung-Yeop;Baek, Jae-Ho;Park, Sang-Gon;Han, Hyun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.678-678
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    • 2009
  • 환경 소음,진동 개선의 측면에서 철도 레일 하부로 전달되는 진동 및 구조소음을 효과적으로 차단하기 위하여 국내에서도 탄성지지 구조의 플로팅 슬라브를 적용하는 경우가 증가하고 있다. 플로팅 슬라브 구조설계에 있어 주안점은 슬라브 자체 중량에 비하여 열차 중량과 열차 주행간에 발생하는 동하중이 2$\sim$3배 이상 높아 열차 주행 안정성을 고려해야 하는 점이며 열차의 고속화 경향에 따라 동하중의 증가는 더욱 커지고 있다. 특히, 열차의 구조 동특성과 동하중의 주파수 특성을 고려할 경우 슬라브 구조의 동적 설계변수(고유진동수, 감쇠비 등) 결정이 매우 제한되고 있음을 고려하면 탄성지지부의 감쇠 및 강성의 가변 특성의 부여는 매우 중요하다 할 수 있다. 본 연구에서는 MR 댐퍼와 MR 방진고무 등의 반능동 소재를 사용하여 열차 주행간에 발생하는 탄성지지 슬라브의 진동을 제어하는 시뮬레이션을 수행함으로써 적용 가능성을 확인하고자 한다.

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Integrated Analysis of Hydrodynamic Motions and Structural Behavior of Large-Scaled Floating Structures using AQWA-ANSYS Coupling (AQWA-ANSYS 연계에 의한 대형 부유구조체의 파랑운동-구조거동 통합해석)

  • Lee, Du-Ho;Jeong, Youn-Ju
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.6
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    • pp.601-608
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    • 2011
  • In order to design floating structures, it should be required to evaluate hydrodynamic motions and structural behavior under the wave loadings. Then, structural behavior of floating structures should be evaluated including the effects of wave-induced hydraulic pressure subjected to floating structures. However, there has been a problem to exactly evaluate structural behavior of floating structures since it was difficult to directly connect wave-induced hydraulic pressure resulting from hydrodynamic analysis with structural analysis model. In this study, in order to exactly evaluate structural behavior of floating structures under the wave loading, integrated analysis of hydrodynamic motion and structural behavior was carried out to the large-scaled floating structure. The wave-induced hydraulic pressure resulting from hydrodynamic analysis AQWA were directly mapped to structural analysis model ANSYS bia Workbench interface of ANSYS Inc.. As the results of this study, it was found that the integrated analysis of this study evaluate exactly structural behavior of floating structures under the wave loadings since this method can directly reflect wave-induced hydraulic pressure resulting from hydrodynamic analysis to structural analysis model. Also, as the results of structural behavior evaluation, it was found that the tensile stress on the top slab was maximized at the wave direction of $0^{\circ}$, and tensile stress on the bottom slab was maximized at the wave direction of $45^{\circ}$, respectively.

Examination for Structural Safety of Floating Slab Design and Shear Connector (플로팅 슬래브 설계와 전단연결재의 구조안전성 검토)

  • Park, Sung-Jae;Ma, Chang-Nam;Lee, Jong-Ho;Lee, Du-Hwa
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.374-374
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    • 2011
  • Recently the construction of railway sections passing the central area of cities and stations under railway lines are increasing, and then it is urgently required to take the countermeasures against the railway vibration and the second-phase noise radiated from it. The most efficient countermeasure, out of technologies developed up to now, is the floating slab track which is the track system isolated from the sub-structure by springs. In other countries, the source technologies for anti-vibration design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the system design technology and technologies for key components are not yet developed, the foreign system are being introduced without any adjustment, and the key component, vibration isolator, depends on imports. In this study, based on the results of previous studies of the dust-control device installation using the slab and go through time after lifting impressive when stepped on power generated by the cross-section of the slab and shear connection re-examined the structural stability.

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Structural Performance and Behavior of Concrete Floating Container Terminal by Live Load Distributions (활하중 분포에 따른 콘크리트 부유식 컨테이너 터미널의 구조성능 및 거동)

  • Lee, Du-Ho;Jeong, Yun-Ju;You, Young-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.1
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    • pp.72-80
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    • 2015
  • In this study, comparative analysis has been performed with regard to a bending stress and deformation at bottom slab of a concrete floating container terminal by live load distributions. In addition, a structural performance and behavior of the floating structure is considered using a numerical analysis. Through reviewed structural performance of a floating structure by live load distribution, the structure presented tensile behavior by two live load cases (A, B, D-type). Then, the other live load cases (C, E, F, G, H, I, J-type) shows compressive behavior. Especially, immoderately compressive stress was generated on bottom slab at specific load distribution. but, that should be decreased through controling buoyancy pre-flexion. Through reviewed structural behavior, slopes of structure by four live load cases (B, E, F, H-type) were exceeded in design criteria of mega-float. It should be estimated that it get out of the load case at loading container. In all, the present study can be considered as a benchmark of a floating container terminal in the absence of analysis and will be used to guide-line about serviceability of concrete floating container terminal.

Analytical Study on Buoyancy Preflexion Effects on Structural Performance of Concrete Floating Structure (부력 프리플랙션 효과가 콘크리트 부유구조체의 구조성능에 미치는 영향에 대한 해석적 연구)

  • Lee, Du-Ho;Jeong, Youn-Ju
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.2A
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    • pp.75-83
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    • 2012
  • In this study, an analytical studies were carried out for the buoyancy preflexion method to improve structural performance of concrete floating structures. The buoyancy preflexion means that the preflexion effects were induced to the floating structure due to the difference in buoyancy between the pontoon modules composing the floating structures. In order to verify the buoyancy preflexion effects, an analytical studies were carried out for the floating structures. The size and dimensions of FE model were determined through the structural design process. The parameter of this analytical study was length ratios of central module part, which induces buoyancy preflexion effects, to the total length. The analysis results were pre-compression on the bottom concrete slab and displacement of freeboard due to buoyancy preflexion effects. These results were processed according to the loading step, buoyancy preflexion loads on the bottom and live loads on the topside. Then, the buoyancy preflexion effects on structural performance was analyzed. As the results of this study, it was found that the buoyancy preflexion significantly influence on structural performance of floating structures. According to the length ratio, the buoyancy preflexion effects have a tendency of parabolic form and maximized at the length ratio of 40~60%. The buoyancy preflexion method is simple in principle and easy in application. Also, it can effectively induce pre-compression on the bottom concrete slab. Therefore, it can be concluded that the buoyancy preflexion method contribute to the improvement of structural performance and decreasing of the cross-sectional depth of floating structures.

Floor Impact Noise Level for Concrete Slab Integrated with Floor Finishing Layers (콘크리트 슬래브와 바닥 상부구조가 일체된 바닥구조의 바닥충격음)

  • Mun, Dae Ho;Oh, Yang Ki;Jeong, Gab Cheol;Park, Hong Gun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.2
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    • pp.130-140
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    • 2016
  • Floating floor is most commonly used at apartment houses in Korea for thermal insulation and reducing impact noise. But it in proven that the floating floor is not effective for reducing the floor impact noise in low frequency range. In most cases, impact sound pressure level under 63 Hz frequency band were actually increased by the resonance of resilient material, lightweight concrete and the finishing mortar installed on it. In this paper, an integrated floor system consist of 70 mm light weight concrete and 40 mm finishing mortar successively installed on the concrete slab was suggested to avoid the resonance. Integrated floor system increases total flexural stiffness and mass per unit area. The natural frequencies of first and second vibration mode were increased and acceleration response and floor impact sound level was decreased in all measurement range.

Heavy-weight Impact Noise Reduction of Concrete Slab Reinforcement Using F.R.P (F.R.P 재료 보강에 의한 신개념 중량충격음 저감대책)

  • Jeong, Jeong-Ho;Yoo, Seung-Yup;Lee, Pyoung-Jik;Jeon, Jin-Yong;Jo, A-Hyoung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.383-386
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    • 2005
  • Low frequency heavy-weight impact noise is the most irritating noise in Korean high-rise reinforced concrete apartment buildings. This low frequency noise is generated by foot traffic due to the fact that Koreans do not wear shoes at home. The transmission of the noise is facilitated by a load bearing wall structural system without beams and columns which is used in these buildings. In order to control low frequency heavy-weight impact noise, floating floors using isolation materials such as glass-wool mat and poly-urethane mat are used. However, it was difficult to control low frequency heavy-weight impact sound using isolation material. In this study, reinforcement of concrete slab using beams and plate was conducted. Using the FEM analysis, the effect of concrete slab reinforcement using FRP(fiber-glass reinforced plastic) on the bang machine impact vibration acceleration level and sound were conducted at the standard floor impact sound test building. The $3{\sim}4dB$ floor impact vibration acceleration level and impact sound pressure level were reduced and the natural frequency of slabs were changed.

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