• Title/Summary/Keyword: Hull girder load

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Optimum Structural Design of Pipe Loops Used in Large Vessels(I) (대형 선박의 파이프 루프 최적구조설계(I))

  • Park, Chi-Mo;Jang, Dae-Oh;Han, Sam-Duck
    • Journal of Ocean Engineering and Technology
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    • v.21 no.5
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    • pp.47-54
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    • 2007
  • Ship structures are subject to severe environmental loads causing appreciable hull girder deflection which in turn affects the piping system attached to the main hull in the form of displacement load. While this load may cause failure in the pipes, loops have been widely adopted as a measure of preventing this failure with the idea that they may lower the stress level in a pipe by absorbing some portion of the displacement load. But as the loops also have some negative effects such as causing extra manufacture cost, deteriorating the function of the pipe and occupying extra space, the number and the dimensions of the loops adopted need to be minimized. This research develops a design formula for pipe loops. The accuracy of the proposed design formula was verified by comparing two results respectively obtained by the proposed formula and MSC/NASTRAN. The paper ends with the sample example showing the efficiency of the proposed formula.

Ultimate Longitudinal Strength Analysis of Ship′s Hull Girder by Idealized Structural Unit Method (이상화(理想化) 구조요소법(構造要素法)에 의한 선체구조(船體構造)의 최종종강도(最終縱强度) 해석(解析))

  • Jeom-K. Paik
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.1
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    • pp.139-149
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    • 1991
  • In this paper, an efficient method for the ultimate longitudinal strength analysis of the double skin hull girder is presented by using idealized structural unit method. Idealized plate element subjected to biaxial load is developed taking account of initial deflection and welding residual stress. Interaction effect between local and global buckling in the whole structure is also taken into consideration. The reserve strength factor and reliability index for the example 40K double skin product oil carrier are evacuated against the ultimate longitudinal strength. It is concluded that the prudent method seems to be useful in the sense that the computing time required is very short while giving the reasonable solution.

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Strength Analysis for PAU Seat of FPSO (FPSO 선의 PAU SEAT 강도 해석)

  • HA T.M.;Kim S.S.;SONG M.K.
    • Special Issue of the Society of Naval Architects of Korea
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    • 2005.06a
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    • pp.90-96
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    • 2005
  • This paper presents the results of the reliability analysis of PAU (Preliminary Assembly Unit) seat of the floating Production Storage and Off1-loading Unit (FPSO) The main aim of the analysis was to demonstrate that a sufficient safety of structural members is guaranteed against PAU loads, internal and external pressure, and hull girder moments. Topside loads for PAU design are based on owner's request. According to the seat type, topside loads are classified into maximum values of same seat type for design efficiency. Totally, 26 loading cases for each model are used for this analysis with the combination of the reactions of PAU loafing and the hull girder bending moments according to LR offshore (2). The analysis results are evaluated according to the acceptance criteria for yielding given in LR offshore and guidance note (3) and The panel buckling resistance is verified by LR offshore and SDA (4). For 900,000 bbls FPSO, the PAU support foundation analysis using 3-D F.E. model is carried out to verify the structural adequacy of PAU foundation and structure members in way of PAU. The modified structures in way of PAU support are safe against considered load cases and all stresses in way of PAU support are within design criteria.

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A Study on ULCS Fatigue Damage Considering the Variation of Cargo Weight Distribution (화물 중량 분포 변화에 따른 초대형 컨테이너선의 피로 손상에 대한 연구)

  • Yi, Minah;Choi, Shin-pyo;Park, Jun-bum
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.4
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    • pp.667-679
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    • 2022
  • Fatigue damage analysis of ships includes parameters considering operational factors. Due to these operational variables, there is a difference between the fatigue damage estimated during the design stage and the actual accumulated fatigue damage. Likewise, there are various loading conditions for the real container ships, but at design stage the fatigue damage is calculated by applying the representative loading conditions. Moreover, although the difference in fatigue damages is expected when the actual and design loading conditions are applied, there are few studies on the contributions of the fatigue damage based on the loading conditions of container ships. In this paper, fatigue contributions were investigated from various cargo weight distributions. The hull girder loads calculated through seakeeping analysis and fatigue damages obtained by performing spectral fatigue analysis were identified under new loading conditions. As a result, it was found that the variation of cargo weight distribution in the container ship brought about changes in the hull girder loads and fatigue damage by affecting the hull girder stress.

A Study on the Lateral Pressure Effect for Ultimate Strength of Ship Platings (선체판부재의 최종강도에 대한 횡압력의 영향에 관한 연구)

  • Park Joo-Shin;Ko Jae-Yong;Lee Jun-Kyo;Lee Kyung-Hwan
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.583-591
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    • 2005
  • The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design of ship structures, it is of crucial importance to bitter understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

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An Experimental Study on the Ultimate Longitudinal Strength of Ship Structures Damaged due to Side Collision (충돌 손상된 선체구조의 최종 종강도에 관한 실험적 연구)

  • Lee, Tak-Kee;Rim, Chae-Hwan
    • Journal of Ocean Engineering and Technology
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    • v.22 no.2
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    • pp.85-90
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    • 2008
  • Ships in bad weather conditions are likely to be subjected to accidental loads, such as high bending moment, collision, and grounding. Once she has damage to her hull, her ultimate strength will be reduced. This paper discusses an investigation of the effect of collision damage on the ultimate strength of a ship structure by performing a series of collapse tests. For the experiment, five box-girder models with stiffeners were prepared with a cross section of $720mm\;{\times}\;720mm$ and a length of 900mm. Of the five, one had no damage and four had an ellipse shaped damage area that represented the shape of the bulbous bow of a colliding ship. The amount of damage size was different between models. Among the damaged models, the damage in three of them was made by cutting the plate and stiffener, and in one by pressing to represent collision damage. Experiments were carried out under a pure bending load and the applied load and displacements were recorded. The ultimate strength was reduced as the damage size increased, as expected. The one with the largest amount of damage had damage to 30% of the depth, and its ultimate strength was reduced by 19% compared to the undamaged one. The pressed one has higher ultimate strength than those that were cut. This might be due to the fact that the plate around the pressed damage area contributes to the ultimate strength, whereas the cut one has no plate to contribute.

A Study on the Buckling & Ultimate Strength for Ship's Plate with Cutout (선체유공판의 좌굴 및 최종강도에 관한 연구)

  • 고재용;박주신;박성현
    • Proceedings of KOSOMES biannual meeting
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    • 2003.05a
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    • pp.167-172
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    • 2003
  • Place that have cutout inner bottom and girder and floor etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight piping etc.. Because cutout's existence gnaws in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic buckling strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step of ship. Therefore, and, reasonable elastic buckling strength about perforated plate need design ultimate strength. Calculated ultimate strength change several aspect ratioes and cutout's dimension. and thickness in this investigation. Used program applied ANSYS F.E.M code transformation finite element law that is mediocrity finite element analysis code.

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Development of Buckling and Compressive Ultimate Strength Formulations for Rectangular Plate with Cutout (압축하중을 받는 유공판의 좌굴 및 최종강도 설계식 개발)

  • 박주신;고재용
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.10a
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    • pp.237-244
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    • 2004
  • Plate that have cutout inner bottom and girder and floor etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight, piping etc.. Because cutout's existence gnaws in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic buckling strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step of ship. Therefore, and, reasonable elastic buckling strength about perforated plate need design ultimate strength. Calculated ultimate strength change several aspect ratioes and cutout's dimension, and thickness in this investigation. Used program applied ANSYS F.E.M code based on finite element method.

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The Development of Design Formulas for Pipe Loops Used in Large Vessels(II) (대형 선박의 파이프 루프 설계식 개발(II))

  • Park, Chi-Mo;Yang, Park-Dal-Chi;Lee, Jong-Hoon
    • Journal of Ocean Engineering and Technology
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    • v.23 no.1
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    • pp.158-163
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    • 2009
  • Many longitudinal pipes in ships are subject to considerable loads, caused by hull girder bending in the ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted to prevent such failure, based on the idea that they can lower the stress level in a pipe byabsorbing some portion of these loads. But as the loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of these loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the flexibility effect of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results obtained from the proposed formulas and MSC/NASTRAN. This paper concludes with a sample application of the proposed formulas, showing their efficiency.

Development of Design Formulas for Pipe Loops Used in Ships Considering the Curvature of Corners (코너부 곡률을 고려한 선박용 파이프 루프 설계식 개발)

  • Park, Chi-Mo;Yang, Park-Dal-Chi
    • Journal of Ocean Engineering and Technology
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    • v.23 no.4
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    • pp.91-99
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    • 2009
  • Many longitudinally arranged pipes in ships are subject to considerable displacement loads caused by the hull girder bending of ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted as a measure to prevent such failure, with the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But since such loops have some negative effects, such as causing extra manufacturing cost and occupying extra space, the number and dimensions of the loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the effects of the curvature of loop corners and the flexibility of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper ends with a sample application of the proposed formulas showing their efficiency.