• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.39-47
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• 2003

A study of the structural strength evaluation on the doubler plate, considering various load cases that were subjected to in-plane and out of plane combined load, has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate for various load cases, elasto-plastic large deflection analysis is introduced, including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed, based on the results. In order to compare the doubler structure with the original strength of main plate, without doubler, simple formulas for the evaluation of the equivalent flat plate thickness are derived for each load case, respectively, based on the additional series of analysis of flat plate structure. Using these derived equations, the thickness change of an equivalent flat plate is analyzed according to the variation of various design parameters of doubler platesome design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas are discovered, and these relations are formulated for the future development of simple strength evaluation formula of general doubler plate structure.

• Journal of the Korean Society of Industry Convergence
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• v.15 no.1
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• pp.5-11
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• 2012

The Buckling of the member under compressive stress is likely to occur, which is an important factor determining the strength of structures. The objective of this study was to evaluate the member buckling strength of a circular hollow steel with ball joints and to compare with design specifications for load resistance factor of our country. Furthermore, we would like to suggest basic data for evaluation of buckling length of a circular hollow steel with ball joints according to comparative analysis. These results were summarized as follows: Buckling stress according to the test results on buckling was 1.21 times greater than LSD specifications of our country estimated the entire length of circular hollow steel with ball joints as buckling length. In addition, it was 1.16 times greater than when estimating the length except the ball as buckling length and 1.14 times grater than when excluding the ball and sleeve. Therefore, when estimating buckling stress of circular hollow steel with ball joints, their buckling length may be measured by the length except ball and sleeve.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.94-94
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• 2011

배관 구조물에서는 내부 미세 균열에서부터 국부 좌굴, 볼트 풀림, 피로 균열 등과 같이 다양한 형태의 손상이 복합적으로 발생 가능하다. 이러한 복합 손상은 배관 구조물의 누수, 누유 등의 사고를 야기할 수 있다. 하지만 기존의 단일 스케일 계측 시스템으로부터 복합 손상에 의한 실시간 누수를 진단하기는 매우 어렵다. 본 연구 단계에서는 누수를 야기하는 복합 손상을 효율적으로 진단하기 위하여 선행 연구에서 제안된 압전센서를 이용한 자가 계측 회로 기반의 다중 스케일 계측 시스템을 구조물의 복합 손상 진단에 적용하였다. 자가 계측 회로 기반 다중 스케일 계측 시스템은 크게 두 가지 형태의 신호를 계측한다. 첫 번째 스케일은 임피던스 계측으로부터 특정 주파수 대역폭에 대한 구조 응답을 계측하며, 두 번째 스케일은 유도 초음파 계측으로부터 단일 중심 주파수에 해당하는 구조물의 응답을 계측한다. 복합 손상을 손상 유형별로 분류하기 위하여 E/M 임피던스(Electro-mechanical impedance)및 유도 초음파(Guided wave) 계측으로부터 추출한 특성을 이용하여 2차원 손상지수를 계산하고 이를 지도학습 기반 패턴인식 기법(Supervised learning based pattern recognition) 중 확률론적 신경망 기법(Probabilistic Neural Network, PNN)에 적용한다. 제안된 기법의 적용성 검토를 위하여 파이프 구조물에 인위적으로 다중 손상을 생성시켜 시험을 수행하였다. 본 연구에서 제안된 기법이 실제 배관 구조물에 성공적으로 적용된다면 손상 부재의 거동 및 구조물 성능의 손상에 대한 영향을 효율적으로 진단하고 평가함으로써 배관 구조물의 효과적인 유지관리가 가능할 것으로 예상된다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.427-434
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• 2005

In this study, to develop composite bridge deck of many advantages such as light weight, high strength, corrosion resistance and high durability, profile design, laminate design and finite element analysis were carried out. In the analysis, 5-girder single span bridge with composite deck was considered. Deflection serviceability, failure criteria and web buckling were evaluated. Composite deck of designed profile was fabricated with pultrusion process. The coupon tests were conducted for the fabricated deck and the results were described.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.6
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• pp.11-19
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• 2001

A series of test on concrete-filled composite columns was preformed to evaluate structural performance under axial compression and cyclic lateral loading. It was presented that concrete-filled composite columns had high strength, high stiffness and large energy-absorption capacity on account of mutual confinement between the steel plate and filled-in concrete. A cross section analysis procedure developed to predict the moment-curvature relation of composite columns was proven to be on accurate and effective method. The ductility factor and the response modification factor were evaluated for the seismic design of concrete-filled composite columns. It was shown that concrete-filled composite columns could be used as a very efficient earthquake-resistant structural member.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.185-195
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• 2010

This paper presents the experiment results for a CFT column confined by carbon fiber sheets(CFSs) under an axial load. Nine specimens were constructed and axial compression tests were conducted. The main experiment parameters were diameter-thickness ratio(D/t), reinforcing CFSa, and the attachment of a cushion gap between surface of steel tube and CFSs. The load-displacement curves of the specimens were obtained from the compression tests. Finally, it was concluded that the CFT column with a gap had grater ductility capacity improvement that the CFT column confined by CFSs.

• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.311-320
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• 2009

This paper presents the experimental results of an experiment on the current rectangular CFT columns and rectangular CFT columns additionally confined by carbon fiber sheets(CFS) under axial loading. The main experimental parameters were the layer numbers of the CFS and the depth-to-thickness ratio. Nine specimens were prepared according to the experimental parameter plans, and axial compression tests were conducted. From the tests, the failure procedure, the load-axial deformation curve, the maximum axial strength, and the deformation capacity of the CFT columns and the confined CFT columns were compared. Finally, it was seen that the maximum axial strengths of the CFT increased more significantly than that of the current CFT columns because of delayed local buckling.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.171-180
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• 2005

Bending performances of aluminum square tube beams reinforced by aluminum plates under three point bending loads have been evaluated using experimental tests combined with theoretical and finite element analyses. A finite element simulation for the three-point bending test was performed. Basic properties of aluminum materials used for initial input data of the finite element simulation were obtained from the true stress-true strain curves of specimens which had been extracted from the Al tube beams. True stresses were determined from applied loads and cross-sectional area records of a tensile specimen with a rectangular cross-section by real-time photographing, and true strains were obtained from in-situ local elongation measurements of the specimen gage portion by the multi-point scanning laser extensometer. Six kinds of aluminum tube beam specimens adhered by aluminum plates were employed fur the bending test. The bending deformation behaviors up to the maximum load described by the numerical simulation were in good agreement with experimental ones. After passing the maximum load, reinforcing plate was debonded from the aluminum tube beam. An aluminum tube beam strengthened by aluminum plate on the upper web showed an excellent bending capability.

• Journal of Korean Association for Spatial Structures
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• v.3 no.2 s.8
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• pp.69-75
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• 2003

In case of rectangular lattice dome which shearing rigidity is very small, it has a concern to drop Buckling strength considerably by external force. So, by means of system to increase buckling-strength, there is a method of construction that lattice of dome is one with roof material. In a case like this, shearing rigidity of roof material increases buckling-strength of the whole of structure and can be designed economically from the viewpoint of practice. In case of analysis is achieved considering roof material that adheres to lattice of dame, there is method that considers the rigidity that use effective width frame as method to evaluate rigidity of roof material. therefore, this study is aimed at deciding effective width of roof material united with rectangular lattice dome to evaluate rigidity of roof material by effective width of frame and investigating how much does rigidity of roof material united with lattice of dome increase buckling-strength of the whole of structure according to rise-ratio. Conditions of loading are vertical-type-uniform loading. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.4
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• pp.198-206
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• 2020

In this study, the dynamic structural behavior of pressure vessels due to pressure pulse initiated by implosion of neighbouring airbacked equipments including Unmanned Underwater Vehicles (UUV), sensor system, and so on were dealt with for the structural design and safety assessment of pressure hulls of submarine. The dynamic buckling and collapse responses of pressure vessel in deep sea were investigated considering the effects of initial hydrostatic pressure and fluid-structure interactions. The governing equations for circular cylindrical shells were formulated theoretically assuming a relatively simple displacement fields and the derived nonlinear simultaneous ordinary differential equations were analysed by developed numerical solution algorithm. Finally, the introduced safety assessment procedures for the dynamic buckling behaviors of pressure hulls due to implosion pressure pulse were validated by comparing the theoretical analysis results with those of experiments for examples of simple cylinders.