• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.62-70
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• 1989

For the conduct of optimum design for such complicated and large structures as ship structure by direct structural analysis such as finite element method, it is very important problem that the process needs much computational efforts due to the repeated structural analysis. In this study, the reanalysis technique based on the modified reduced basis method is applied in the process to reduce the computing time required in repeated structural analysis. Numerical examples to simple grillage and actual ship structure are performed and applicability of reanalysis technique to structural optimization process is discussed.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.612-618
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• 2007

There are a lot of openings, holes and slots in ship structural members. It is not easy to solve the troubles around the openings adequately at the detail design stage, because there are a lot of concerning locations. There are not also clear design rules of classification societies and it is not possible to apply direct calculation for all the concerning members. Therefore, it is necessary to set up simplified approach such as a standard or guidance in order to decide the opening design quickly. For this study, guidance and regulations of each classification and several companies were surveyed. Grillage analysis and the refined mesh method were used to evaluate the strength around hole considering boundary condition and more detailed member arrangement. As a result, the standard for opening design was established and verified.

• Steel and Composite Structures
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• v.18 no.4
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• pp.853-871
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• 2015

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.

• Structural Engineering and Mechanics
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• v.11 no.3
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• pp.259-272
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• 2001

The impact behavior of a multigirder concrete bridge under single and multiple moving vehicles is studied based on correlated road surface characteristics. The bridge structure is modeled as grillage beam system. A 3D nonlinear vehicle model with eleven degrees of freedom is utilized according to the HS20-44 truck design loading in the American Association of State Highway and Transportation Officials (AASHTO) specifications. A triangle correlation model is introduced to generate four classes of longitudinal road surface roughness as multi-correlated random processes along deck transverse direction. On the basis of a correlation length of approximately half the bridge width, the upper limits of impact factors obtained under confidence level of 95 percent and side-by-side three-truck loading provide probability-based evidence for the evaluation of AASHTO specifications. The analytical results indicate that a better transverse correlation among road surface roughness generally leads to slightly higher impact factors. Suggestions are made for the routine maintenance of this type of highway bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.313-321
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• 1999

To design steel box girder bridge, designers have taken the classical load distribution coefficient methods. Due to the rapidly developing computer technique, steel box girder bridge is simply modeled as grillage method for analyzing the girder, or as fully finite element method for more accurate and detailed analysis. Recently, cruciform space frame method is developed for modeling and analyzing it more simply and easily compared with finite element method. So, this study for the examination of upper methods' characteristics loaded unit moment load and analyzed the distortional deflection with shell element method and cruciform space frame method, and for three span three girder steel box bridge, loading DB-24 loads, analyzed it by upper methods and compared the results.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.363-372
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• 1999

This study proposes useful analysis models for automatic design of orthotropic steel deck bridges. For the selection of the best or the most proper analysis model this paper presents various analysis models based on grillage model, which are then compared with each other in terms of reliability of analysis, computing time and effectiveness. Also the selected analysis models are compared with Pelikan-Esslinger method well-known for orthotropic steel deck bridge analysis. The effectiveness of proposed analysis models is demonstrated by means of a numerical example that is a three-span continuous (60m+80m+60m=200m) orthotropic steel-box girder bridge.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.109-118
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• 1994

In this study, an optimization method to design the hull structure of the surface effect ships with twin hulls is proposed for the purpose of minimization of weight based on the regulations of DnV class, and computer programs following the method are developed. The method uses simple formulas as to bending and buckling strength of beams and plates to design local structures, and considers the effect of interaction between longitudinal girders and transverse web frames by grillage analysis and calculates torsional strength of the cross structure by the simplified method. Global optimization of the midship section is attained by integration of optimized substructures. According to optimized results by applying the method to the designed ship, reduction of 20 percent of hull weight can be shown, and optimum transverse frame space can be obtained.

• Journal of Navigation and Port Research
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• v.31 no.3 s.119
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• pp.235-245
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• 2007

Stiffened steel plates are basic structural members on the deck and bottom structure in ship, offshore. It has a number of one sided stiffeners in either one or both directions, the latter structure was called grillage structure. At the ship structural desgn stage, one of the major consideration is evaluation for ultimate strength of the hull girder. In general, it is accepted that hull girder strength can be represented by the local strength of the longitudinal stiffened panel. In case of considering hogging condition in a stormy sea, stiffened panel was acting on the bottom structure under axial compressive load induced hull girder bending moment, also simultaneously arising local bending moment induced lateral pressure load. In this paper, results of the structural analysis have been compared with another detailed FEA program and prediction from design guideline and a series analysis was conducted consideration of changing parameters for instance, analysis range, cross-section of stiffener, web height and amplitude of lateral pressure load subjected to combined load (axial compression and lateral pressure load). It has been found that finite element modeling is capable of predicting the behaviour and ultimate load capacity of a simply supported stiffened plate subjected to combined load of axial compression and lateral pressure load It is expected that these results will be used to examine the effect of interaction between lateral pressure and axial loads for the ultimate load-carrying capacity based on the Ultimate Limit State design guideline.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.100-112
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• 2002

Naval vessels are not regulated by the class rules, but by the special regulations. This study introduces the concept and characteristics of the regulations of U.S. Navy which has been the most reliable standards in design of naval vessels in Korea, and intends to help designers to comprehend the effect of each regulation on design results. Also, an optimum structural design method combined with the structural analysis theory is proposed for naval vessels following the regulations of U.S. Navy and is applied to the design of a naval vessel. After application of the optimum design method, its validity is shown and an optimum design of midship section is obtained. In addition, the optimum spaces or longitudinals and transverse web frames are found and the effect of main design variables can be investigated.

• Structural Engineering and Mechanics
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• v.8 no.1
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• pp.85-102
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• 1999

With the advent of computer, the finite element method has become a most powerful numerical method for structural analysis. However, bridge designers are reluctant to use it in their designs because of its complex nature and its being time consuming in the preparation of the input data and analyzing the results. This paper describes the development of a computer based finite element model using the idea of eccentric beam elements for the analysis of slab-on-girder bridges. The proposed method is supported by a laboratory test using a reinforced concrete bridge model. Other bridge analytical schemes are also introduced and compared with the proposed method. The main aim of the comparison is to prove the effectiveness of the shell and eccentric beam modelling in the studies of lateral load distribution of slab-on-girder bridges. It is concluded that the proposed finite element method gives a closer to real idealization and its developed computer program, SHECAN, is also very simple to use. It is highly recommended to use it as an analytical tool for the design of slab-on-girder bridges.