• Earthquakes and Structures
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• 제11권3호
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• pp.421-443
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• 2016

When conducting seismic assessment of an asymmetric building, it is essential to carry out three-dimensional analysis considering all the possible directions of seismic input. For this purpose, the author proposed a simplified procedure is to predict the largest peak seismic response of an asymmetric building subjected to horizontal bidirectional ground motion acting in an arbitrary angle of incidence in previous study. This simplified procedure has been applied to torsionally stiff (TS) asymmetric buildings with regular elevation. However, the suitability of this procedure to estimate the peak response of an asymmetric building with vertical irregularity, such as an asymmetric building with setback, has not been assessed. In this article, the pushover-based simplified procedure is applied to estimate the peak response of asymmetric buildings with bidirectional setback. Nonlinear dynamic (time-history) analysis of two six-storey asymmetric buildings with bidirectional setback and designed according to strong-column weak beam concept is carried out considering various directions of seismic input, and the results compared with those estimated by the proposed method. The largest peak displacement estimated by the simplified method agrees well with the envelope of the dynamic analysis response. The suitability assessment of the simplified procedure to analysed building models is made as well based on pushover analysis results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.949-954
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• 2003

In this paper, simplified modeling approach describing the hysteretic behavior of reinforced concrete columns is discussed. The inelastic response of a reinforced concrete column or pier subjected to cyclic deformation reversals or earthquake ground motion is evaluated by use of lumped hysteretic representation. For this purpose, the hystertic model under axial force variation is developed and implemented into a nonlinear finite element analysis program. The analytical predictions obtained with the new formulation are compared with test results and reveal accuracy and applicability in terms of strength and stiffness. In addition, comparison between results with and without axial force variation stresses the importance of the proposed approach.

• 한국해안·해양공학회논문집
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• 제28권1호
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• pp.7-12
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• 2016

본 연구에서는 선박충돌로부터 교량을 방호하는 파일형 선박충돌방호공과 충돌선박의 간이충돌모델을 개발하고 이를 검증하였다. 선박은 선수의 비선형반력을 고려하여 모델링하였다. 충돌방호공의 모델은 파일에서 상부슬래브의 하단과 지중에 2개의 소성힌지가 발생하는 것으로 구성하였다. 충돌중 발생하는 운동에너지와 위치에너지 및 변형에너지를 고려하여 운동방정식을 유도하고 이를 해석하는 시스템을 개발하였다. 선박과 구조물에 대한 정밀 충돌해석을 수행하여 개발된 간이모델이 충돌거동을 정확히 모사할 수 있음을 보였다.

• Earthquakes and Structures
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• 제18권2호
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• pp.233-248
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• 2020

In this article, one of the procedures to design viscous dampers proposed in literature is applied to 3D asymmetric-plan buildings, considering different distributions for the damping coefficients, which are assumed to be proportional to specific structural or response parameters. The main purpose was to investigate the effectiveness of different vertical and in-plan distributions of the damping coefficients of nonlinear viscous dampers for the seismic retrofit of existing buildings. For comparison purposes, all the distributions were applied utilizing both a simplified and an extended method for the 3D structures, where the simplified method takes into account only the translation in the seismic direction, and the extended method considers the translations along the two orthogonal directions together with the floor rotations. The proposed distributions were then applied to a typical case study involving an asymmetric-plan six-storey RC building. The effectiveness of the different distributions was examined through time-history analyses, assuming nonlinear behaviour for both the viscous dampers and the structural elements. The results of the nonlinear dynamic analyses were examined in terms of maximum and residual inter-storey drifts, peak floor accelerations and maximum damper forces.

• 한국정밀공학회지
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• 제20권2호
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• pp.192-198
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• 2003

A finite element analysis of end-to-end artery/PTFE anastomosis has been presented in this study to evaluate the distribution of compliance and stresses in the vicinity of the anastomosis due to any mismatch in compliance characteristics. The artery wall was assumed to be made of linear isotropic material in this simplified model and a nonlinear analysis and convergency study with respect to increasing meshed element numbers were performed with a mean artery pressure loading of the artery-PTFE model. Also, sub-modeling method was Introduced to progress the accuracy of the finite element analysis. The results are as follow : 1. A hypercompliant zone on the artery side was observed around 4.Omm from the anastomosis and a high hoop stresses in the wall of artery and PTFE was dominant. 2. An artery displays large deformation so that nonlinear analysis and sub-modeling method was used. 3. An anastomosis with the thinner thickness and larger diameter PTFE (B type) could reduce the compliance disagreement.

• 제어로봇시스템학회논문지
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• 제20권3호
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• pp.261-269
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• 2014

This paper provides an overview of the basics and recent studies of Lyapunov-based nonlinear adaptive control, the aim of which is to improve or maintain the performance and stability of the closed-loop system by cancelling out the presumable uncertainties in the nonlinear system dynamics. The design principles are essentially based on Lyapunov's direct method. In this survey, we provide a comprehensive overview of Lyapunov-based nonlinear adaptive control techniques with simplified effective design examples, which are to be elaborated as related recent results are gradually shown. The scope of the survey contains research on singularity problems in adaptive control, the techniques to deal with linearly and nonlinearly parameterized uncertainties, robust neuro-adaptive control, and adaptive control methodologies combined with various nonlinear control techniques such as sliding-mode control, back-stepping, dynamic surface control, and optimal/$H_{\infty}$ control.

• 한국강구조학회 논문집
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• 제16권1호통권68호
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• pp.11-20
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• 2004

본 눈문은 C.F.T구조에서 폐단면인 각형강관기둥과 H형강보의 접합방법중의 하나인 외측형 다이아프램을 대상으로 한다. 본 연구에서의 내력평가는 기존의 단순인장형 접합부 실험결과를 기초로 항복선이론을 이용한 내력평가, 범용 유한요소해석 프로그램을 이용한 비선형 해석, 규준식 등을 통하여 수행되었다. 항복선이론은 수정된 K. Morita 역학모델을 이용하였고, 범용 유한요소해석프로그램은 Abaqus/Standard를 사용하였으며 비탄성 정역학적 유한요소해석을 하였다. 규준식에서의 최대내력 예측식은 장기하중에 대한 계수와 재질을 고려한 항복비를 적용하였으며, 규준식에서의 항복내력은 비충전형의 경우 2.6의 안전율을 갖는 값으로 하였고, 충전형의 경우 2.2의 안전율을 갖는 값으로 하였다. 연구결과, 본 연구에 사용된 기존의 단순인장형 접합부 내력평가는 항복선이론, 유한요소해석, 규준식을 통하여 모두 가능한 것으로 판단되며, 이들 중 규준식이 기존의 실험결과를 가장 과소평가하였다. 유한요소 해석결과에서의 내력과 변형모듈은 기존의 단순인장형 접합부 실험결과와 잘 일치하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.151-158
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• 2002

In the present design concept, the nonlinear behaviour of bridges is at lowed under large earthquake. The nonlinearity is, however, localized like pier, bearing, etc. Especially, pier columns are most important members for seismic performance. It is, however, difficult to solve the problem how the nonlinearity of columns should be modelled. In this study, the fiber element is used for modelling pier column. The element is a kind of structural elements like frame element, and it can model the distributed plasticity of plastic hinge. A 3 span continous bridge is taken for seismic analysis. First, the nonlinear static analysis the column at fixed support are performed so that the characteristics of column is analyzed. Second, Linear and nonlinear dynamic analysises using simplified model for longitudinal direction are carried out and the results are analyzed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.419-426
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• 2003

Simplified modeling approach for the seismic behavior of a reinforced concrete bridge is investigated in this paper. For this purpose, a hysteretic axial-flexure interaction model was developed and implemented into a nonlinear finite element analysis program. Thus, the seismic response of reinforced concrete bridge piers was evaluated by the simplified point hinge representations. Comparative studies for reinforced concrete bridge piers indicated that the analytical predictions obtained with the new formulations showed a good correlation with experimental results. In addition, seismic response analysis of a reinforced concrete bridge utilizing the simplified point hinge model revealed the adequacy and applicability of the present development.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.481-486
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• 1997

In the paper, a simplified method for nonlinear analysis of reinforced concrete structures is presented, which is based on timeoshenko beam theory and constitutive equations that are given by the relation of average stress and average strain for concrete and reinforcing bars. Especially, this method consider shear deformation and determine the failure mode. In this paper, 1-D beam element model and program considering shear deformation are suggested. In addition, program procedure is presented briefly and the results are plotted with test examples.