• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.742-745
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• 2010

본 논문은 초고층구조물의 해석방법으로 탄성변형과 아울러 시간의존성을 가진 크리프와 건조수축에 의한 비탄성변형을 고려한 비선형 시공단계 해석법을 제시한다. 기존의 초고층구조물 해석에서 주로 행하는 기둥 축소량 해석은 실무자의 경험과 프로그램을 통한 간략화에 맞추어져 있다. 이는 실제 시공 시 발생하는 구조해석 요소들을 충분히 반영하지 못하여 계산 값과 실제 값 사이에 오차가 발생된다. 비선형 시공단계 해석은 실제 시공 때 발생되는 해석변수들을 고려한 단계별 해석의 수행이 가능하며, 시간의 의존성을 가진 creep과 shrinkage의 효과를 함께 고려하여 일괄해석의 문제점을 구조해석 단계에서 실제상황에 가까운 해석을 가능하게 할 수 있다. 이를 위해 시공단계해석이 가능한 범용 프로그램을 이용한 50층 규모의 3차원 골조 프레임 모델 예제 해석을 통하여 기존 해석법들과의 비교, 분석으로 시간의 의존성을 고려한 시공단계해석의 필요성을 제시한다. 본 논문에는 범용프로그램인 SAP2000(ver.14)와 CEB-FIP모델 코드를 사용 하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.519-527
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• 1987

Simple procedures have been formulated to compute approximate natural frequency of nonlinear systems by the use of variational principle. These procedures are applicable to motion of large amplitudes, even to systems which are not linearizable. The results obtained by these procedures have been found to have good agreements with computer solutions and exact solutions for systems having piece-wise linear springs and polynomial springs.

• Computational Structural Engineering
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• v.5 no.4
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• pp.13-23
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• 1992

본 소고는 철근콘크리트 구조물에 관련된 현재의 실험적, 해석적 연구의 수준을 정리 요약한 것으로서 이력모델에 따른 철근콘크리트 구조물의 응답과 모델의 선택시에 빈번히 만나게 되는 문제점 및 해석시 응답모델의 선택 등에 대해 기술하였다. 실제적으로 R/C 구조물의 비선형 이력모델은 그 범위가 매우 넓고 다양하기 때문에 일률적으로 설명하기가 매우 어려운 점이 있다. 여기서는 철근콘크리트 구조물의 이력모델의 종류 및 범위에 대하여 소개하고 그 특성 및 형성과정에 대해 간략하게 설명하기로 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.947-954
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• 2016

A simplified analysis method is first proposed in order to determine an optimized initial shape of cable-stayed bridges including all unstrained element lengths without using complicated nonlinear FE analysis. The unstrained-length based FE method is then presented using the unstrained lengths by the simplified analysis. To demonstrate validity and accuracy of the proposed method, Incheon bridge model having the fabrication camber is constructed and initial shaping analysis is performed using the presented method and commercial finite element analysis program, MIDAS. Resultantly it is shown that the initial solutions by the proposed algorithm are well optimized and in good agreement with those by MIDAS except for axial displacements of the main member.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.5
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• pp.33-39
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• 2010

This study develops an approximate procedure for incremental dynamic analysis (IDA) using modal pushover analysis (MPA) with empirical equations of the inelastic displacement ratio ($C_R$) and the collapse strength ratio ($R_C$). By using this procedure, it is not required to conduct linear or nonlinear response history analyses of multi- or single- degree of freedom (MDF) systems. Thus, IDA curves can be effortlessly obtained. For verification of the proposed procedure, the 6-, 9- and 20-story steel moment frames are tested under an ensemble of 44 ground motions. The results show that the MPA-based IDA with empirical equations of $C_R$ and $R_C$ produced accurate IDA curves of the MDF systems. The computing time is almost negligible compared to the exact IDA using repeated nonlinear response history analysis (RHA) of a structure and the original MPA-based IDA using repeated nonlinear RHA of modal SDF systems.

• Computational Structural Engineering
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• v.10 no.1
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• pp.19-26
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• 1997

본 고에서는 막구조물의 설계시 반드시 수행되어양 하는 형상해석과 응력-변형해석과정을 간략하게 언급하였다. 막구조물의 설계과정은 3부분의 주요 단계로 나뉘어진다: 형상탐색, 하중해석, 재난도 생성. 여기에서는 형상탐색과 하중해석 단계만을 다루었다. 언급된 비선형 유한요소해석 과정은 형상탐색과 하중해석 모두에 적용할 수 있다. 또한, 형상탐색해석에 대한 3가지 방법 즉, 등장력곡면, 비등장력곡면 그리고 비선형변위해석 등이 초기 평형형상을 결정하는 방법으로 소개되었다. 형상탐색에 대한 여러 접근법의 사용 가능성은 다양한 막구조물에 대한 설계를 편리하게 한다. 여기에서는 언급되지 않았으나, 우리나라에도 형상해석, 응력해석 뿐 아니라 막구조물의 시공과정에 대한 시공해석과 막면 형성에 매우 중요한 단계인 재단도해석(Cutting Pattern Analysis)에 대한 연구와 막구조물의 적용분야를 넓히려고 하는 응용연구가 절실히 필요한 것으로 판단된다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.587-588
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• 2011

본 논문에서는 강사장교의 극한강도 및 파괴모드를 간략하게 예측할 수 있는 간단하고 빠른 해석법을 제안하였다. 기존의 비탄성 고유치해석의 기본 개념을 바탕으로 기둥 요소에 대한 수렴 기준을 보였고, 사장교 구조 시스템의 거더 및 주탑 요소에서 보-기둥 거동을 고려하기 위한 새로운 수렴 기준을 제시하였다. 제시된 방법의 타당성 검증을 위하여 중앙경간 길이와 거더의 높이를 변화시킨 강사장교 모델에 대하여 제안된 비탄성 고유치 해석과 비선형 탄소성 해석 결과를 비교하였다. 해석 결과, 제안된 수렴 기준을 적용한 비탄성 고유치 해석은 기존에 기둥의 수렴기준을 적용했던 방법에 비하여 강사장교의 극한강도를 보다 정확히 예측할 수 있었다. 또한, 제안된 방법은 강사장교의 파괴모드 역시 근사하게 모사 가능함을 알 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.17-22
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• 2010

Generally, there are Chua's Circuit, Lorenz Circuit and Duffing circuit in the chaos circuit. Among these chaos circuits, Chua's circuit is well known to make the electronic parts easily. Chua's circuit is the constitute of the linearelements. These are constitute of Resistor component(R), inductor component(L), capacitor(C), and nonlinear element which is constitute of nonlinear resistor. However, L element have a difficult problem to implement real hardware by using commercial parts. Due to this, it has a saturation characteristic. In this paper, we analyzed the simplified Chua's circuit which is replace L to C by PSPICE program. Because L element has a difficult problem to make a real hardware, L has a saturation characteristic and we also confirm this analysis as the result.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.177-188
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• 2006

Conventional nonlinear finite element analysis requires complicated modeling and analytical technique. Furthermore, it is difficult to interpret the analytical results presented as the stress-strain relationship. In the present study, a design-oriented analytical method using the truss model was developed. A reinforced concrete member to be analyzed was idealized by longitudinal, transverse, and diagonal line elements. Basically, each element was modeled as a composite element of concrete and re-bars. Simplified cyclic models for the concrete and re-bar elements were developed. RC beams and walls with various reinforcement details were analyzed by the proposed method. The inelastic strength, energy dissipation capacity, deformability, and failure mode predicted by the proposed method were compared with those of existing experiments. The results showed that the proposed model accurately predicted the strength and energy dissipation capacities, and to predict deformability of the members, the compression-softening model used for the concrete strut element must be improved.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.351-360
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• 2014

The purpose of this research is to introduce the simplified equivalent frame model for the equivalent lateral force procedure, the response spectrum procedure and nonlinear procedure according to ASCE7-10 in order to reduce the time of performance and reasonably evaluate the effect of applying the damping system with the various conditions for the analysis and the variable. In this research, the seismic performance assessment and the design of the damping system were conducted through the nonlinear time history analysis based on the performance based seismic design in ASCE7-10 in regard to applying the damping system to apartment buildings which is lately issued. The optimal design based on the 75% of seismic base shear was performed for an apartment building. The seismic performance assessment were conducted to check the safety of the building, and the economic evaluation was performed by comparing the amount of resource for the optimal designed building with the amount of resource for the original building. In addition, hysteresis dampers was applied to the apartment building, and the suggested equivalent frame model was performed using the damping system design in ASCE7-10, then its control effects were proved in the full scale model of the apartment building which was used in this research.