• 한국해양공학회지
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• 제29권4호
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• pp.309-316
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• 2015

Lifting lugs are frequently used in shipyards to transport and turn over the blocks of ships and offshore structures. With the development of shipbuilding technology, blocks have increased in size, and block management technology has assumed a more important role in shipbuilding to enhance the productivity. For the sake of economics, as well as the safe design of a lug structure, a more rational design procedure based on a rigorous structural analysis is needed. This study investigated the strength characteristics of T-type lugs, considering the influence of blocks on which lugs are attached, by varying the in-plane and out-of-plane load direction. In this paper, the ultimate strength is also addressed for cases that include or do not include blocks in the strength analysis. In the present results, when there was a load acting in the normal direction to the block surface, the strength characteristics became poor, and the ultimate strength decreased. This paper ends by describing the need for further study to develop a more rational design for a lug structure.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.55-60
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• 2005

선체구조 부재에는 이중저의 거더 및 늑판등에서 유공을 가진 판이 많이 사용되고 있고, 이는 중량 경감, 사람 및 화물의 이동, 배관 등의 목적으로, 보통은 강도상 큰 문제가 없는 부위에 위치하지만, 때로는 불가피하게 높은 응력이 작용하는 부위에 설치해야 할 경우도 있다. 이러한 판에 유공의 존재는 면내 하중에 의한 탄성좌굴강도 및 최종강도에 큰 영향을 주게 된다. 따라서, 유공판의 탄성좌굴강도 및 최종강도 평가는 선박의 초기 구조설계단계에서 구조부재 치수를 결정할 때 검토해야 할 중요한 설계기준 중의 한가지 이다. 그러므로, 유공판에 대한 합리적인 신뢰적인 탄성좌굴강도 및 최종강도 평가가 필요시 되고있다. 본 연구에서는 다양한 종횡비와 유공의 치수비 그리고 세장비의 영향을 고려하여 탄소성대변형유한요소법을 근간으로 한 구조해석프로그램인 ANSYS를 사용하여 수치계산을 수행하였다.

• 한국강구조학회 논문집
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• 제12권5호통권48호
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• pp.537-547
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• 2000

현장에서 자주 사용하는 강관 플랜지이음은 고력볼트를 사용한 인장접합의 일종이다. 이 이음에 있어서 응력전달은 고력볼트를 조을때 얻어지는 재료간의 높은 압축력을 이용해서 행하여진다. 그리고 플랜지이음의 역학성상에 대해서 충분하게 해명되어 있지 않고 설계방법도 확립되어 있다고 말하기 어렵다. 이상의 문제점을 포함한 플랜지이음에 대해서 종국내력에 착안을 둔 설계법을 제안하고자 한다. 본 연구의 목적은 리브 붙은 고력볼트 강관 플랜지의 이음에 대한 설계방법을 세우기 위한 기초자료를 얻는데 있고 또한 리브나 링이 개입된 형식에 있어서 직경이 다른 강관 플랜지의 이음이 설계될 수 있는지 조사하는데 있다.

• 대한조선학회지
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• 제20권1호
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• pp.11-20
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• 1983

In this paper elastic-plastic large deflection analysis of ship structural members, plates, stiffened plates and cylindrical shallow shell, are performed by the finite element method. And for the consideration of the yielded propagation through the depth of the member, the layered element approach is employed. The present method is justified by comparing its results with those of experiment and others. As results, the nonlinear behavior and the ultimate strength curves are shown, which can be used in the design of the plates and the stiffened plates under compression, and the applicability to the shell structures is suggested. The analysis results are as followings. (1) The results of the approximate equations as well as those of buckling analysis may not guarantee precisely the safety of the structures in some cases and the optimum in other cases. Therefore they may not show the design criteria for the optimal design. (2) As the initial deflection increases, its effects on the ultimate strength of the structure generally increases, and the ultimate load, therefore, decreases. (3) This approach can be applied to the shell type structures. (4) The present method can be applied to the various structures composed of plate and beam members, for example, plates with hole and the stiffened plates with hole stiffened by spigot, doubler and/or stiffener, for the optimal design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.339-342
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• 2005

This paper presents flexural test results of concrete beams reinforced with GFRP and conventional steel reinforcement for comparison. The beams were tested under static loading to investigate the effects of reinforcement ratio and compressive ,strength of concrete on cracking, deflection, ultimate capacity and mode of failure, This study attempts to establish a theoretical basis for the development of simple and rational design guideline. Test results show that ultimate capacity increases as the reinforcement ratio and concrete strength increase. The ultimate capacity increased up to $8\%-25\%$ by using high strength concrete. The deflection at maximum load of GFRP reinforced beams was about three times that of steel reinforced beams. For GFRP-reinforced beams, the ACI code 440 design method resulted in conservative flexural strength -estimates.

• Steel and Composite Structures
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• 제17권6호
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• pp.907-927
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• 2014

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of $1450kg/m^3$ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권1호
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• pp.47-61
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• 2013

This study compares the Residual ultimate longitudinal strength - grounding Damage index (R-D) diagrams produced by two analysis methods: the ALPS/HULL Intelligent Supersize Finite Element Method (ISFEM) and the design formula (modified Paik and Mansour) method - used to assess the safety of damaged ships. The comparison includes four types of double-hull oil tankers: Panamax, Aframax, Suezmax and VLCC. The R-D diagrams were calculated for a series of 50 grounding scenarios. The diagrams were efficiently sampled using the Latin Hypercube Sampling (LHS) technique and comprehensively analysed based on ship size. Finally, the two methods were compared by statistically analysing the differences between their grounding damage indices and ultimate longitudinal strength predictions. The findings provide a useful example of how to apply the ultimate longitudinal strength analysis method to grounded ships.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.473-483
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• 2017

Comprehensive consideration regarding influence mechanisms of initial imperfections on ultimate strength of spherical shells is taken to satisfy requirement of deep-sea structural design. The feasibility of innovative numerical procedure that combines welding simulation and non-linear buckling analysis is verified by a good agreement to experimental and theoretical results. Spherical shells with a series of wall thicknesses to radius ratios are studied. Residual stress and deformations from welding process are investigated separately. Variant influence mechanisms are discovered. Residual stress is demonstrated to be influential to stress field and buckling behavior but not to the ultimate strength. Deformations are proved to have a significant impact on ultimate strength. When central angles are less than critical value, concave magnitudes reduce ultimate strengths linearly. However, deformations with central angles above critical value are of much greater harm. Less imperfection susceptibility is found in spherical shells with larger wall thicknesses to radius ratios.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 춘계학술발표회
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• pp.141-146
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• 2005

선체는 기본적으로 판부재들의 조합으로 구성되어 있으며 이들중 상당수는 유공판(Perforated plate)이다. 선체에 설치된 유공판으로서는 선체 상갑판 해치(하역시설로 사용), 선저부의 거더와 플로어(중량경감과 선박 건조 및 검사시 통로확보용), 다이어프램(중량경감 및 파이프 관통의 목적)둥이 있다. 이들 유공판에 하중이 작용하면 좌굴과 최종강도 특성이 크게 변화할 뿐만 아니라 수반되는 면내응력도 재 분포하게 되어 심각한 강도문제를 야기 시킬 수 있다. 실적선에서는 유공주위에 스티프너 보강을 통하여 취약한 좌굴강도 보완하고 있으며, 유공을 고려한 최적의 유공보강판 모델을 적용한 좌굴강도 및 최종강도를 파악할 필요성이 대두시 되고 있다. 이와 같은 측면에서 각 조선소에서는 각국 선급들이 제시하는 유공판의 좌굴설계식을 사용하여 강도계산을 하고 있으나 임의의 유공크기에 대찬 좌굴강도 및 최종강도 평가법을 찾기란 매우 어려운 일이다. 본 연구에서는 실선에서 사용중인 유공보강판의 모델을 조사하여 비선형유한요소법을 적용하여 면내 압축하중이 작용하는 경우에 대해서 유공의 크기와 웹 치수를 변화시켜가며, 최종강도 시리즈 해석을 수행하고 압축최종강도에 미치는 영향을 검토하였다.

• Structural Engineering and Mechanics
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• 제42권4호
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• pp.507-530
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• 2012

Age-related problems especially corrosion and fatigue are normally suffered by weatherworn ships and aging offshore structures. The effect of corrosion is one of the important factors in the Common Structural Rule (CSR) guideline of the ship design based on a 20 or 25 years design life. The aim of this research is the clarification of the corrosion effect on ultimate strength of stiffened panels on various types of double hull oil tankers. In the case of ships, corrosion is a phenomenon caused by the ambient environment and it has different characteristics depending on the parts involved. Extensive research considering these characteristic have already done by previous researchers. Based on this data, the ultimate strength behavior of stiffened panels for four double hull oil tankers such as VLCC, Suezmax, Aframax, and Panamax classes are compared and analyzed. By considering hogging and sagging bending moments, the stiffened panels of the deck, inner bottom and outer bottom located far away from neutral axis of ship are assessed. The results of this paper will be useful in evaluating the ultimate strength of an oil tanker subjected to corrosion. These results will be an informative example to check the effect of ultimate strength of a stiffened panel according to corrosion addition from CSR for a given type of ship.