• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.3
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• pp.191-198
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• 2013

In this paper, the effects of uncertain material constant on the nonlinear behavior of steel frames with semi-rigid joints are examined. As to the probabilistic model, a normal distribution is assumed to simulate the uncertain elastic modulus of steel material. A nonlinear structural analysis program, which can consider both semi-rigidity in joints of the steel frames and uncertainty in the material constant, is developed. Including the geometric, material and connection nonlinearites which are the parameters of nonlinear behavior of steel frames, probabilistic analysis is conducted based on the Monte-Carlo simulation. In the probabilistic analyses, we consider the three different cases for random variables. The deterministic analysis results are shown to be in good agreement with those of the previous research results in the literature. As to the probabilistic analyses, it is observed that the coefficient of variation(COV) of displacements increases as the loading increases, and that the values of COV are dependent on the structural features of the frames.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.489-497
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• 2002

Nonlinear behavior and large deformation cannot be analyzed using techniques based on linear theory. Nonetheless, they are emerging as gradually huge and complex structures. In addition, the optimum design of structure is necessary in the development of high-performance computation and numerical methods. as well as stricter design-criterion. Therefore, the structural problems in engineering that are limited to the linear region must be extended to the nonlinear region. Likewise, structural behavior must be accurately analyzed. In turn, this requires considering the expected problems beforehand. Only then can an efficient, economical, and optimized structure be designed. This paper presents the solution of the geometrical nonlinear problem of anisotropic cylindrical shell. The characteristics of the geometrical nonlinear behavior of anisotropic circular cylindrical shells may vary according to several causes. e.g., change of fibers, curvature in the circumferential direction, subtended angle, aspect, etc. Parametric studies were conducted to determine the effect of factors on the large deflection behavior of laminated shells, with interesting observations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.174-177
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• 2011

비선형 정적 해석법(NSPs)은 최근 구조물의 지진해석방법으로서 그 사용성을 인정받고 있다. 비선형 정적 해석법은 직관적으로 구조물의 지진해석을 수행할 수 있는 등의 장점으로 빌딩구조물의 지진해석법으로 널리 사용되고 있지만, 기본 진동모드에 의해서 구조물의 거동이 지배되지 않는 구조물의 경우에는 그 사용성에 대한 연구가 매우 제한적이다. 이를 개선하기 위한 고차모드의 기여분을 반영할 수 있는 비선형 정적 해석법들이 제시 되었지만, 교량 구조물에 사용함에 있어서는 여전히 지진의 특성에 따라 그 사용성 및 신뢰성이 크게 변화하는 문제가 발생한다. 이 논문에서는 지진의 특성을 고려할 수 있는 두가지 지수를 제시하고, 이를 이용하여 비선형정적 해석법의 적용성을 사용단계에서 알아 낼 수 있는지에 대한 연구를 진행하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.36-43
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• 2002

Thermopiezoelastic snap-through phenomena of piezolaminated plates are investigated by applying an are-length scheme to Newton-Raphson method. Based on the layerwise displacement theory and von Karman strain-displacement relationships, nonlinear finite element formulations are derived for the thermopiezoelastic composite plates. From the static and dynamic viewpoint, nonlinear thermopierzoelastic behavior and vibration characteristicx are stuied for symmetric and eccentric structural models with various piezoelestric actuation modes. Present results show the possibility to enhance the performance, namely thermopiezoelastic snapping, induced by the excessive piezoelectric actuation in the active suppression of thermally buckled large deflection piezolaminated paltes.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.503-513
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• 2007

The seismic responses of a building are affected by the connection characteristics that have effects on structural stiffness. In this study, push-over analysis and time history analysis were performed to estimate structural behavior of 2D eight-story unbraced steel structures with partially restrained composite connections using a nonlinear dynamic analysis program. Nonlinear $M-{\theta}$characteristics of connection and material inelastic characteristics of composite beam and steel column were considered. The idealization of composite semi-rigid connection as fully rigid connection yielded an increase in initial stiffness and ultimate strength in the push-over analysis. In time history analysis, the stiffness and hysteretic behavior of connections have effects on base-shear force, maximum story-drift and maximum moment in beams and columns. For seismic waves with PGA of 0.4 g, the structure with the semi-rigid composite connections shows the maximum story-drift with less than the life safety criteria by FEMA 273 and no inelastic behavior of beam and column, whereas in the structure with rigid connections, beams and columns have experienced inelastic behaviors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.28-33
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• 2005

Nonlinear aeroelastic characteristics of a two dimensional typical section model with bilinear plunge spring are investigated. Doublet-point method(DPM) is used for the calculation of supersonic unsteady aerodynamic forces which are approximated by using the minimum-state approximation. For nonlinear flutter analysis structural nonlinearity is represented by an asymmetric bilinear spring and is linearized by using the describing function method. The linear and nonlinear flutter analyses indicate that the flutter characteristics are significantly dependent on the frequency ratio. From the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a wide range of air speeds below or above the linear flutter boundary. The nonlinear flutter characteristics and the nonlinear aeroelastic responses are investigated.

• Journal of the Society of Disaster Information
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• v.7 no.1
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• pp.75-85
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• 2011

In this study, the behavior were analyzed for the bow collision event. The model of protective Structure was consist of slab, RCP and non-linear soil spring. The ship was modeled by bow and midship. The bow model was composed by elastic-plastic shell elements, and the midship was composed by elastic solid element. According to the weight of the ship's change from DWT 10000 until DWT 25000 increments 5000. The head-on collision was assumed, its speed was 5knot. Analysis was carried out ABAQUS/Explicit. As the result, increasing the weight of the ship deformability in athletes and to increase the amount of energy dissipated by the plastic could be confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.129-136
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• 2001

본 연구의 목적은 휨을 받는 철근콘크리트 단순보의 비선형 거동을 해석을 통하여 파악하기 위하여 보의 단면을 Layer로 분할하여 각 Layer에 사용된 재료의 특성을 부여하고, 작용하중에 의한 비선형 특성을 응력-변형도 모델을 통하여 반영할 수 있도록 알고리즘을 작성하는 것이다. 본 연구에서 제안한 알고리즘을 사용하면 실험을 위한 보(beam)를 제작하지 않고도 사용재료의 압축 및 인장 실험을 위한 몰드 만을 제작하여 재료에 대한 정확한 응력-변형도 모델을 작성함으로써 합성보의 거동을 수치해석을 통하여 간단하게 파악할 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.103-112
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• 1990

This study examines the characteristics of soil behavior which includes many uncertainties in seismic design, evaluates the dynamic soil properties and studies the soil-structure interaction to generalize the applicability and economy of the available sites. An example analysis is performed for soil-structure system response assuming a containment structure built on site which includes soil layers using both elastic halfspace analysis and FEM analysis against the seismic loads from the actual design. This exercise is performed as a part of the safety analysis and economic assessment of the nuclear power plant built on soils. It includes the preparation of computer program capable of incorporating large nonlinearity in the analysis, resonable evaluation procedures to determine input soil data. Nonlinear FEM analysis of Seed and Idriss model is found suitable for the accurate analysis of dynamic response of soils. Linear FEM analysis using dynamic soil properties at strain level obtained by one-dimensional seismic response, and elastic half-space analysis using dynamic soil properties at strain level under static loads are recommended to evaluate the dynamic soil properties.

• Computational Structural Engineering
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• v.11 no.1
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• pp.96-106
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• 1998

본 연구에서는 복잡한 비선형시스템의 전체적 응답거동의 중요한 (그리고 잠재적으로 유익한) 특성을 상세히 분석하였다. 특히 강성도 및 여기력에 내재된 복잡한 비선형을 소유하는 수중다점계선해양시스템의 분기집합에 내재된 초구조와 혼돈거동의 가능경로에 대하여 해석적 및 수치적으로 분석하였다. 분기는 국부적 안정해석을 통하여 매개변수 영역상에서 확인되었으며, 정상 상태의 분기초구조는 수치해석을 통하여 밝혀졌다. 비선형정도와 해의 차원을 나타내는 공명수를 유도하였으며, 차수공명수를 통해 공명주위의 구조를 밝혔으며 열조화, 울트라조화, 울트라열조화 등과 같은 고도의 비선형 응답의 발생을 예측할 수 있음을 보였다. 결과에서 얻은 초구조는 시스템의 안정성과 이상끌개의 징후를 지배하는 메커니즘임도 밝혔다. 혼돈으로 가는 주기증가의 무한시퀀스에 대한 유연한 변환 외에 돌연한 격발(saddle에 의해 분리된 인접끌개의 충돌)로 인한 혼돈으로의 가능경로도 발견되었으며 이는 수치적으로도 입증되었다.