• 대한조선학회논문집
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• 제43권3호
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• pp.340-350
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• 2006

This paper is concerned with a practical guide for the ultimate longitudinal strength assessments of ships' hull structure. Rigorous non-linear structural analysis for three tanker models has been carried out to examine the ultimate strength behavior. Formula of estimating the ultimate longitudinal strength has been proposed which is modified with the results of non-linear finite element analysis of hull girders. Computational reliability and accuracy of the large-scale non-linear finite element analysis and the proposed simplified formula are verified through comparing their results with that of 1/3 scale frigate model test and DNVs program. Additionally, the ultimate longitudinal strength for ten tanker models is compared with those by the method specified in the 2nd Draft of common structural rule for tankers, which is being developed by IACS.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.284-292
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• 1995

This paper is on experimental study on the behavior of reinforced concrete columns subjected to longitudinal steel ratio To investigate the effects of concrete strength and longitedinal steel ratio on the behavior of reinforced concrete columns. a series of tests were carried out for thirty-six tied reinforced concrete columns with a 100mm square cross section and three slendemess ratio of 15, 30 and 50. And To study and illustrate the change of the ultimate loads and that of displacements, two different concrete strength of 180,26kfg/$\textrm{cm}^2$, 819,36kfg/$\textrm{cm}^2$ and five different longitudinal steel ratio of 0.5, 1.0, 4.0, 5.7 and 10.3% were used. The boundary conditions at the ends were both hinged and the end eccentricities (17mm) were equal and of the same sign. While the ultimate load capacity of high-strength concrete column was much increased when the columns were short, that was not when the columns were slender. The effect of longitudinal steel ratio on the increased of ultimate load of column was more evident for slender columns than for short ones and the ultimate of longitudinal steel ratio were more pronounced with increasing concrete strength. The more inserted the longitudinal steel, the more increased the ultimate load, but the superabundance of longitudinal steel ratio over the limitation of maximum steel ratio in ACI code was used, it was showed that the ultimate load was rather decreased.

• 한국강구조학회 논문집
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• 제11권2호통권39호
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• pp.167-179
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• 1999

판형복부판의 좌굴강도를 높이기 위하여 수평보강재나 수직보강재를 대는 방법이 많이 적용되고 있다. 경제적인 판형의 설계를 위하여 복부판의 두께를 얇게 하는 대신, 복부판의 전단강도를 높이기 위하여 수직보강재를 사용하게된다. 수직보강재가 있는 복부판의 극한전단강도의 산정에 관한 연구는 1960년 초반부터 활발하게 진행되어 왔고, 이 결과가 미국의 AASHTO 시방서(1973)와 영국의 British Standard(1983)에 처음 반영되어 현재에 이르고 있다. 수평보강재의 주 역할은 휨응력에 의한 복부판의 좌굴강도를 높이고 횡변위를 억제하는 것이지만, 부수적으로 전단강도를 증가시키는 효과가 있는 것으로 알려지고 있다. 하지만, 이에 대한 연구의 부족으로 인하여 수평보강재가 복부판의 극한전단강도에 미치는 영향이 실제 설계시 반영되지 않고 있다. 본 연구에서는 실험을 통하여 수평보강재가 판형의 극한전단거동에 미치는 영향을 조사하고 이를 기존의 이론들과 비교 검토하였다.

• 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.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.45-56
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• 2008

Recently, International Association Classification Societies (IACS) has adopted the Common Structural Rules (CSR) for Bulk Carriers and Tankers, which specifies the requirement associated with the ultimate strength of hull girder structure. The theoretical background and the results of verification study are neither well summarized nor released. Furthermore, the requirement is not a form of deterministic formula but a form of program in which source code is not disclosed. The reliability of the non-linear structural analysis program is verified through the comparison with the results of the analysis and the model test. Then, the reliability of the ultimate strength requirement in CSR is checked by comparing with the results of rigorous non-linear analysis.

• Structural Engineering and Mechanics
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• 제46권5호
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• pp.629-644
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• 2013

This paper concerns about the raking damages on the ultimate residual hull girder strength of bulk carriers by applying the modified R-D diagram (advanced method). The limited raking damage scenarios, based on the IMO's probability density function of grounding accidents, were carried out by using sampling technique. Recently, innovative method for the evaluation of the structural condition assessment, which covers the residual strength and damage index diagram (R-D diagram), was proposed by Paik et al. (2012). This concept is applied in the present study and modified R-D diagram, which can be considered vessel size effect, is then proposed. Four different types of bulk carrier structures, i.e., Handysize (37K), Supramax (57K), Kamsarmax (82K) and Capesize (181K) by Common Structural Rule (CSR), were applied to draw the general tendency. The ALPS/HULL, intelligent supersize finite element method, was employed for the ultimate longitudinal strength analysis. The obtained empirical formulas will be useful for the condition assessment of bulk carrier structures. It can also cover different sizes of the bulk carriers in terms of ultimate longitudinal strength. Important insights and findings with useful guidelines developed in this study are summarized.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.247-259
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• 2018

In this study (Part I), an advanced empirical formulation was proposed to predict the ultimate strength of initially deflected steel plate subjected to longitudinal compression. An advanced empirical formulation was proposed by adopting Initial Deflection Index (IDI) concept for plate element which is a function of plate slenderness ratio (${\beta}$) and coefficient of initial deflection. In case of initial deflection, buckling mode shape, which is mostly assumed type in the ships and offshore industry, was adopted. For the numerical simulation by ANSYS nonlinear finite element method (NLFEM), with a total of seven hundred 700 plate scenarios, including the combination of one hundred (100) cases of plate slenderness ratios with seven (7) representative initial deflection coefficients, were selected based on obtained probability density distributions of plate element from collected commercial ships. The obtained empirical formulation showed good agreement ($R^2=0.99$) with numerical simulation results. The obtained outcome with proposed procedure will be very useful in predicting the ultimate strength performance of plate element subjected to longitudinal compression.

• 대한조선학회논문집
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• 제50권4호
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• pp.255-261
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• 2013

This paper presents prediction of ultimate longitudinal strength of a VLCC, "Energy Concentration" for which many benchmark studies have been carried out, based on kinematic displacement method proposed by Tayyar and Bayraktarkatal (2012). Kinematic displacement theory provides semi-analytical solution of average compressive strengths for various kinds of stiffened panels. The accuracy of average compressive strengths obtained from formulas of CSR(common structural rules) for tankers and kinematic displacement method are discussed in the fore part of this paper. Hull girder ultimate strengths using Smith method are also compared for different average compressive strengths. By comparing them with other benchmark results, it is concluded that the new method provides lower bounds, because hull girder strengths under the sagging and hogging moment conditions approach nearly lower bounds.

• 대한조선학회지
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• 제22권1호
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• pp.31-37
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• 1985

In ship's structure, deck and bottom plate are main strength member subjected to the inplane load due to longitudinal bending, i.e. tensile and/or compressive load. The deck and bottom plate are subdivided into many plate members by stiffeners and girders longitudinally and transversely. Since the plate members are thin, it is likely to be collapsed under compressive load, and when we consider the local strength of deck and bottom, the plate members play an important role in the longitudinal strength. Therefore the precise analysis of their compressive ultimate strength is required for the optimal design of ship's structures. In this paper, the modified analytical method using the incremental form of principle of virtual displacement is introduced to determine the compressive ultimate load of plate members. The results by the present method is satisfactory, and the present method is more effective and economical than the finite element method.

• Structural Engineering and Mechanics
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• 제46권4호
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• pp.519-531
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• 2013

To have a better understanding of the torsional mechanism and influencing factors of PC composite box-girder with corrugated steel webs, ultimate torsional strength of four specimens under pure torsion were analyzed with Model Test Method. Monotonic pure torsion acts on specimens by eccentric concentrated loading. The experimental results show that cracks form at an angle of $45^{\circ}$ to the member's longitudinal axis in the top and bottom concrete slabs. Longitudinal reinforcement located in the center of cross section contributes little to torsional capacity of the specimens. Torsional rigidity is proportional to shape parameter ${\eta}$ of corrugation and there is an increase in yielding torque and ultimate torque of specimens as the thickness of corrugated steel webs increases.