• Title, Summary, Keyword: 충돌에너지소산

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Behavior characteristics of Pile-type vessel collision protective structure (파일형 선박충돌방호공의 거동특성)

  • Lee, Jeong-Woo;Park, Jun-Seok;Lee, Gye-Hee
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.433-436
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    • 2010
  • 본 논문에서는 파일형 선박충돌 방호공에 선박이 충돌하였을 때 방호공의 거동을 해석하였다. 방호공의 구조는 상부슬래브, RCP 말뚝 및 이를 지지하는 지반은 비선형 지반스프링으로 모델링 하였다. 상부슬래브 8절점요소로 모델링 하였으며 철근과 콘크리트로 구성되어있다. RCP 말뚝은 철근망과 충진콘크리트로 구성되어있으며 충돌 시 파괴거동을 표현할 수 있는 Damaged Plasticity로 모델을 사용하였고 Shell 요소로 모델링 하였다. 선박충돌 시 선박의 강성에 따른 거동 특성을 파악하기 위해 선박을 강체모델과 실제모델에 대한 해석을 수행하였다. 선박과 교량의 충돌은 정면충돌로 고려하였으며, 충돌속도는 3.3m/sec로 가정하였다. 선박과 방호공과의 충돌 해석은 비선형 해석 프로그램인 ABAQUS/Explicit을 이용하여 수행하였으며, 이를 통하여 선박 충돌 시 방호공의 에너지 거동을 분석하였다. 해석결과 선박의 강성이 커질수록 슬래브의 변형 및 소산 에너지량이 커지는 것을 확인할 수 있었다.

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Collision Analysis of Submerged Floating Tunnel by Underwater Navigating Vessel (수중운항체에 대한 해중터널의 충돌해석)

  • Hong, Kwan-Young;Lee, Gye-Hee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.5
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    • pp.369-377
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    • 2014
  • In this paper, to recognize the collision behavior between a submerged floating tunnel(SFT) and underwater navigation vessel(UNV), both structures are modeled and analyzed. The SFT of collision point is modeled tubular section using concrete with steel lining. The other part of SFT is modeled elastic beam elements. Mooring lines are modeled as cable elements with tension. The under water navigation vessel is assumed 1800DT submarine and its total mass at collision is obtained with hydrodynamic added mass. The buoyancy force on SFT is included in initial condition using dynamic relaxation method. The buoyancy ratio (B/W) and the collision speed are considered as the collision conditions. As results, energy dissipation is concentrated on the SFT and that of the UNV is minor. Additionally, the collision behaviors are greatly affected by B/W and the tension of mooring lines. Especially, the collision forces are shown different tendency compare to vessel collision force of current design code.

A Study on Behaviors of Pile Protective Structures by Simplified Collision Model (간이충돌모델을 이용한 파일형 선박충돌방호공의 충돌거동 연구)

  • Lee, Gye Hee
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.1
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    • pp.31-38
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    • 2016
  • In this paper, the deformation-energy curves of the plastic hinges and the vessel bow, which are the major energy dissipation mechanism of a pile protective structures, were estimated, and the parametric study was performed by using those curves to apply the simplified collision model which developed in the previous study. Considered parameters were the mass of slab, the number of piles, the mass of vessel and the collision speed. As results, the difference of energy dissipation mechanism of two pile types (filled and non-filled) were revealed, and the collision behaviors of the protective structures could be tuned by the control of the inertia mass of capping slab. Therefore the simplified collision model can be used in a primary design and optimal design.

Vessel Collision Analysis of an Underwater Soil Slope using Coupled Eulerian-Lagrangian Scheme 2: Parametric Study (Coupled Eulerian-Lagrangian 기법을 이용한 선박의 수중사면 충돌해석 2 : 매개변수연구)

  • Lee, Gyehee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.33 no.1
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    • pp.25-33
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    • 2020
  • In this study, parametric analyses are performed using the coupled Eulerian-Lagrangian scheme for the collision behaviors of a vessel and an underwater slope that constitutes part of an artificial protective island. The vessel parameters considered in the analysis are bow angle, stem angle, draft, and impact velocity. The gradient of the slope, the friction coefficient between the bow and the slope, and soil strength are considered as parameters of the slope. For each parameter, the dissipated collision energy and the collision force are estimated from the behavior of the vessel, and the energy dissipation mechanism is identified in terms of the ground deformation. The collision force is assumed as an exponential function, and the effects of the parameters are estimated. As a result, only two parameters, the gradient of the slope and the friction coefficient between the vessel and the soil, can affect the exponential coefficient of the function. The dissipated energy by the soil can thus be estimated adequately. The relationship between the volume of the soil pushed out by the bow and the dissipated collision energy is estimated as a linear function. This relationship is independent of the magnitude of the collision energy, and affected more by the friction coefficient and the soil strength than by the parameters of the vessel.

Analysis of Ship Collision Behavior of Pile Supported Structure (파일지지 구조물의 선박 충돌거동에 대한 해석)

  • Bae, Yong Gwi;Lee, Seong Lo
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.3A
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    • pp.323-330
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    • 2008
  • The ship collision analysis of steel pile group as protection system of bridge in navigable waterways was performed to analyze the structural characteristics of protective structure during ship collision. The analysis encompassed finite element modeling of ship and pile, modeling of material non-linearity, hard impact analysis, displacement-based analysis and soft impact analysis for collision scenarios. Through the analysis of hard impact with a rigid wall, impact load for each collision type of ship bow was estimated. In the displacement-based analysis the estimate of energy which protection system can absorb within its maximum horizontal clearance so as to secure bridge pier from vessel contact during collision was performed. Soft impact analysis for various collision scenarios was conducted and the collision behaviors of vessel and pile-supported protection system were reviewed for the design of protection system. The understanding of the energy dissipation mechanism of pile supported structure and colliding vessel would give us the optimized design of protective structure.

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Collision Behaviors Analysis of Sandwich Concrete Panel for Outer Shell of LNG Tank (LNG외조를 구성하는 샌드위치 콘크리트 패널의 충돌거동해석)

  • Lee, Gye Hee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.6
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    • pp.485-493
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    • 2017
  • In this study, the collision analysis of SCP(Sandwich Concrete Panel) composing the outer tank of LNG storage was performed and its collision behavior was analyzed. For the same collision energy value proposed in BS7777 code, the collision conditions are composed by using two types of missiles and various collision speeds. Nonlinear dynamic analysis models were constructed to perform numerical analysis on the various collision conditions. Also, the collision behavior was analyzed assuming that the second collision with the same collision energy occurs at the same point after the first collision. As a result of the analysis, it was found that with smaller missile and low collision speed had caused larger deformation. The collision energy dissipated in ratio of about 6: 4 in the outer steel plate and the inner filling concrete. In the results of double collision analysis, the final collisional deformation was dominated by the size of the second missile, and the amount of deformation due to the second collision was smaller than that of the first collision because of the membrane behavior of the steel plates. In the offset double collision cases, the largest deformation occurs at the secondary collision point regardless of the offset distance.

Centrifugal Test on Behavior of the Dolphin Structure under Ship Collision (선박충돌 시 돌핀 구조물의 거동에 대한 원심모형실험)

  • Oh, SeungTak;Bae, WooSeok;Cho, SungMin;Heo, Yol
    • Journal of the Korean Geoenvironmental Society
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    • v.12 no.1
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    • pp.61-70
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    • 2011
  • The impact protection system consists of an arrangement of circular sheet pile cofferdams-denoted dolphin structuredeeply embedded in the seabed, filled with crushed rock and closed at the top with a robust concrete cap. Centrifuge model tests were performed to investigation the behaviors of dolphins in this study. Total 7 quasi-model tests and 11 dynamic model tests were performed. The main experimental results can be summarized as follows. Firstly, The experimental force-displacement results for quasi-static tests show a limited influence on the initial stiffness of the structure from the change in fill density and the related change in the stiffness of the fill. And by comparing the dissipation at the same dolphin displacement it was found that the denser fill increase the dissipation by 16% for the 20m dolphin and by 23% for the 30m dolphin. The larger sensitivity for the large dolphin is explained by a larger contribution to the dissipation from strain in the fill. In low level impacts the dynamic force-response is up to 26~58% larger than the quasi-static and the dissipation response is showed larger in small displacement. Hence, it is concluded conservative to use the quasi-static response characteristics in the approximation of the response, and it is further concluded that the dolphin resistance to low level impacts is demonstrated to be equivalent and even superior to the high level impacts.

Impact Performance of Crashworthy Post Utilizing Conservation of Linear Momentum (선운동량 보존의 법칙을 활용한 감충지주의 충돌거동)

  • Ko, Man-Gi;Kim, Kee-Dong;No, Min-Hyung;Yun, Duk-Geun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.12
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    • pp.8966-8976
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    • 2015
  • Unshielded posts on roadside are a critical hazard to the safety of impact vehicle to the posts. A crashworthy post is developed. In the first phase, it dissipates the impact energy by the linear momentum conservation principle while the plastic impact between the post and vehicle takes place, then, the second phase dissipation follows by the deformation of the energy absorbing modules embedded in the guide trough of the foundation. Simulations of impacts to a rigidly connected post and crashworthy post were made using LS-DYNA program, which demonstrated the danger of unshielded rigidly connected post and the effectiveness of the proposed crashworthy post to the 0.9ton-80km/h impact.

A Protection Capacity Evaluation of Vessel Protective Structures by Quasi-Static Collision Analysis (준정적 충돌해석을 통한 선박충돌방공호의 방호능력평가)

  • Lee, Gye-Hee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.6
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    • pp.691-697
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    • 2011
  • In this study, the vessel collision protective structure and the vessel were modeled numerically and the quasi-static collision analysis was performed to evaluate the maximum protection capacity. In the modeling process of protective structure, the nonlinear behaviors of structure and the supporting conditions of ground including pull-out action were considered. In that of collision vessel, the bow of vessel was modeled precisely, because of the nonlinear behaviors were concentrated on it. For the efficient analysis, the mass scaling scheme was applied, also. To evaluate the differences and efficiency, the dynamic analyses were performed for the same model, additionally. Based on the obtained energy dissipation curves of the structure and the vessel, the moment that the collision force affected to the bridge substructures was determined and the maximum allowable collision velocity was evaluated. Because of the energy dissipation bound can be recognized clearly, this scheme can be used efficient in engineering work.

Study on Behavior Characteristics of a Pile-Type Vessel Collision Protective Structure (파일형 선박 충돌방호공의 거동특성 연구)

  • Lee, Gye-Hee;Lee, Jeong-Woo
    • Journal of the Society of Disaster Information
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    • v.7 no.1
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    • pp.75-85
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    • 2011
  • In this study, the behavior were analyzed for the bow collision event. The model of protective Structure was consist of slab, RCP and non-linear soil spring. The ship was modeled by bow and midship. The bow model was composed by elastic-plastic shell elements, and the midship was composed by elastic solid element. According to the weight of the ship's change from DWT 10000 until DWT 25000 increments 5000. The head-on collision was assumed, its speed was 5knot. Analysis was carried out ABAQUS/Explicit. As the result, increasing the weight of the ship deformability in athletes and to increase the amount of energy dissipated by the plastic could be confirmed.