• Journal of Korean Association for Spatial Structures
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• v.8 no.1
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• pp.41-48
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• 2008

Spatial structure is an appropriate shape that resists external force only with in-plane forte by reducing the influence of bending moment, and it maximizes the effectiveness of structure system. the spatial structure should be analyzed by nonlinear analysis regardless static and dynamic analysis because it accompanys large deflection for member. To analyze the spatial structure geometrical and material nonlinearity should be considered in the analysis. In this paper, a geometrically nonlinear finite element model for plane truss structures is developed, and material nonlinearity is also included in the analysis. Arc-length method is used to solve the nonlinear finite element model. It is found that the present analysis predicts accurate nonlinear behavior of plane truss.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.119-124
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• 2008

Space structure is a appropriate shape that resists external force only with in-plane force by reducing the influence of bending moment, and it maximizes the effectiveness of structure system. The space structure should be analized by nonlinear analysis regardless static and dynamic analysis because it accompanies large deflection for member. To analyze the structure of the space structure exactly generally geometrically nonlinear and material nonlinear, complex nonlinear analysis are considered. To settle the weakness that geometric nonlinear problem does not consider nonlinear as per trait and position of the structure material and that the nonlinear matter of structure material also does not consider nonlinear as per geometric form. Therefore, In this paper, analysis is considered geometric nonlinear and material nonlinear simultaneous conditioning, and traced load-deflection curve by using ABAQUS which is the general purpose of the finite element program.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.73-79
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• 2010

In this study, the equivalent elastic modulus of flexible textile composites was predicted by nonlinear finite element analysis. The analysis was carried out considering the material nonlinearity of fiber tows and the geometrical nonlinearity during large deformation using commercial analysis software, ABAQUS. To account for the geometrical nonlinearity due to the large shear deformation of fiber tows, a user defined material algorithm was developed and inserted in ABAQUS. In results, nonlinear stress-strain curve for the flexible textile composites under uni-axial tension was predicted from which effective elastic modulus was obtained and compared to the test result. The effective elastic moduli were calculated for the various finite element models with different waviness ratio of fiber tow.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.417-424
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• 1999

In this paper a nonlinear analysis of three-dimensional steel frames is developed. This analysis accounts for material and geometric nonlinearities. The material nonlinearity includes gradual yielding associated with flexural behaviors. The geometric nonlinearity includes the second-order effects associated with $P-{\delta}\;and\;P-{\Delta}$ effects. The material nonlinearity at the node is considered using the concept of P-M hinge consisting of many fibers. The geometric nonlinearity is considered by the use of stability function. The nonlinearity caused by shear and torsional interaction effects is neglected. The modified incremental displacement method is used as the solution technique. The load-displacements predicted by the proposed analysis compare well with those given by other approaches.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.472-480
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• 2009

The stability analysis for CWR is difficult in the theory itself because both geometric and material nonlinearity should be considered. Also the analysis results are varied according to the loading history. In contrast to the complexity in the theory, the analysis results for CWR on the railway bridges are quite simple and can be predicted because of a small buckling effect and its negligible nonlinearity. In this study, refined nonlinear analysis methods for the stability analysis of CWR on the railway bridges were developed which consider only material nonlinearity beeause the effects of geometric nonlinearity are nominal. In this study, the analysis results can be found within limited number of iterations with idealized linear force-displacement relationship. From the analysis result comparisons, it was found that the stability analysis for CWR on the railway bridges can be performed effectively by this method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.639-642
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• 2011

이 연구에서는 완전 조립식 교량 하부구조의 비선형해석을 위한 전산플랫폼을 개발하였다. 완전 조립식 교량 하부구조의 비선형거동을 정확하게 파악하고 합리적이면서 경제적인 설계기준의 개발을 위한 자료를 제공하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 사용된 부착 또는 비부착 텐던요소는 유한요소법에 근거하며 프리스트레스트 콘크리트 부재의 콘크리트와 텐던의 상호작용을 구현할 수 있다. 그리고 접합면요소는 세그먼트 접합부의 비탄성거동을 예측할 수 있다. 제안된 해석기법은 수치예제에 대하여 비선형거동을 비교적 정확하게 예측하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.734-737
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• 2010

이 연구에서는 프리스트레스트 콘크리트 깊은 보의 비선형해석을 위한 전산플랫폼을 개발하였다. 프리스트레스트 콘크리트 깊은 보의 전단거동을 정확하게 파악하고 합리적이면서 경제적인 설계기준의 개발을 위한 자료를 제공하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 사용된 부착 또는 비부착 텐던요소는 유한요소법에 근거하며 프리스트레스트 콘크리트 부재의 콘크리트와 텐던의 상호작용을 구현할 수 있다. 이 연구에서는 프리스트레스트 콘크리트 깊은 보의 전단거동을 파악하기 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험 결과와 비교하여 그 타당성을 검증하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.43-46
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• 2009

열탄성 부영역, 열탄점소성/손상 부영역, 공유면, 접촉 공유면에 기반을 둔 영역/경계 분할법을 적용하여 재료 비선형성을 갖는 열탄점소성 손상 문제와 경계 비선형성을 갖는 접촉 문제의 효율적인 해석을 제안하였다. 영역 및 경계 분할에 관련된 공유면 및 접촉 공유면에서의 연속 구속 조건을 처리하기 위하여 간단한 벌칙 함수 기법을 적용하였다. 결과적으로 재료 및 경계 비선형성은 소수의 부영역과 접촉 경계면에서 계산되는 유한요소 행렬들에 국한된다. 따라서 적절한 해석 알고리듬을 구성하면 대폭적인 효율성 향상이 가능하게 된다. 대변형과 같은 기하학적 비선형성은 고려하지 않았으며, 간단한 수치 실험을 통해서 열탄점소성 손상 및 접촉 해석의 효율성에 관련된 기본적인 특성을 분석하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.1
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• pp.53-59
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• 2016

Ultrasonic nonlinear evaluation is generally utilized for detection of not only defects but also microdamage such as corrosion and plastic deformation. Nonlinearity is determined by the amplitude ratio of primary wave second harmonic wave, and the results of its comparison are used for evaluation. Owing to the experimental features, the experimental nonlinearity result contains system nonlinearity and material nonlinearity. System nonlinearity is that which is unwanted by the user; hence, it acts as an error and interrupts analysis. In this study, a bulk wave mixing technique is implemented in order to minimize the system nonlinearity and obtain the reliable analysis results. The biggest advantage of this technique is that experimental nonlinearity contains less system nonlinearity than that for the conventional nonlinear ultrasonic technique. Theoretical and experimental verifications are performed in this study. By comparing the results of the bulk wave mixing technique with those of the conventional technique, the strengths, weaknesses, and application validity of the bulk wave mixing technique are determined.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.2 s.48
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• pp.31-38
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• 2006

The purpose of this study is to assess the seismic performance of reinforced concrete bridges using nonlinear finite element analysis. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The proposed numerical method is applied to reinforced concrete bridges and compared.