• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.516-520
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• 2011

본 논문에서는 먼저 흥인지문에 대해 상시진동실험을 수행하고, 그 데이터를 분석하여 흥인지문의 고유진동수, 모드, 감쇠비의 특성을 분석하였다. 그 결과로부터 흥인지문의 병진모드를 파악하였고, 병진모드에서 측정한 여러 기둥의 모드 상대크기와 위상이 동일함을 확인하였다. 저차 병진모드에서 모든 기둥이 같은 방향으로 강성을 발휘하기 때문에 각층의 강성을 합한 등가의 층강성을 가지는 2자유도의 동적강체해석모델을 제시하였다. 이 해석모델은 선형 범위 내에서 거동한다는 것으로 가정하여 층강성을 산정하였다. 실제 흥인지문의 접합부에는 부재간의 이음과 맞춤에 의한 마찰력이 작용한다. 접합부를 누르는 무거운 지붕하중에 의해 이 마찰력은 증가하게 되고, 이로써 횡하중에 저항하게 된다. 이러한 접합부에 강한 횡하중이 작용하게 되면, 접합부의 이완 및 마찰력의 저하 등으로 인하여 횡강성의 저하가 급격히 일어나는 비선형 특성을 갖게 된다. 이러한 흥인지문의 비선형적인 특성을 파악하기 위해 흥인지문 해석모델에 쿨롱 마찰력을 도입하여 비선형적인 해석모델을 제시하였다.

• Computational Structural Engineering
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• v.1 no.1
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• pp.103-112
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• 1988

In this study, the earthquake response of building structures with foundation uplift was investigated. The Winkler foundation model and two-spring model are widely used to represent the interaction between foundation mat and soil. While the analysis using the Winkler foundation model results in more accurate prediction, it requires a complex procedure and longer computation time. In this study, an equivalent two-spring model(S model) is proposed. The S model can represent the Winkler foundation model more accurately and the analysis using the S model is simpler and more effective. The S model is derived by simplifying the nonlinear moment-rotation relationship of foundation mat. The dynamic responses predicted by the S model gave a good agreement to those of the Winkler foundation model.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.87-96
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• 1999

To analyze the dynamic behavior of structure, direct integration and mode superposition may be utilized in time domain analysis. As finite number of frequencies can give relatively exact solutions, mode superposition is preferable in analyzing structural behavior. In non-linear analysis, however, mode superposition is seldom used since time-varying element stiffness changes stiffness matrix, and the change of stiffness matrix leads to the change of essential constants - natural frequencies and mode shapes. In spite of these difficulties, there are some attempts to adopt mode superposition because of low cost compared to direct integration, but the result is not satisfactory. In this paper, a method using mode superposition in non-linear analysis is presented by separating local element stiffness from global stiffness matrix with the difference between linear and non-linear restoring forces to the external force vectors included. Moreover, the hysteresis model changing with the relative deformation in each floor makes it possible to analyze non-linear behavior of structure. The proposed algorithm is applied to shear beam model and the maximum displacement is compared with the result using direct integration method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.1
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• pp.13-20
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• 2021

Recently, various piloti structures have been constructed in Korea to secure residential and parking spaces. However, these piloti structures have been constructed in the form of protruding columns without walls to secure parking spaces on the first floor. In this form, when an earthquake occurs, the column is relatively easily damaged compared to general structures, and such damage can lead to the collapse of the structure. Therefore, in this study, a study on securing the safety of the piloti structure using the MPS (Multi Performance System) seismic isolation device was conducted. Nonlinear dynamic analysis according to the presence or absence of MPS seismic isolation device was performed on the existing piloti structure, and analysis results were compared and analyzed. Finally, each seismic performance evaluation was performed and the superiority of the MPS seismic isolation device was verified.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.71-80
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• 2003

Though a nonlinear time history analysis may be provided to estimate more exactly the seismic performance of building structure, approximation methods are still needed in the aspect of practicality and simplicity, In converting a multi-story structure to an equivalent SDOF system, the mode vectors of the multi-story structure are assumed as the mode shape in elastic state regardless of elastic or elastic-plastic state. However, the characteristics of displacement mode are also changed after the yielding made in the structural elements, because the structure becomes inelastic in each incremental load step. In this research, a method of converting MDOF system to ESDOF system is presented by using nonlinear displacement mode considering the mode change of structures after the yielding. Also, the accuracy and efficiency of the method of the nonlinear displacement mode method of the estimate of seismic response of Mixed Building Structures were examined by comparing the displacements of the roof level of the multi-story building structures estimated from this converted displacement response of ESDOF with the displacement of the roof level through the nonlinear dynamic analysis of the multi-story building structures subjected to an actual earthquake excitation.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.253-256
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• 2008

The objective of this study is to evaluate the seismic weakness of existing nonseismic low-rise piloti-type apartment buildings which have the irregularities of weak story, soft story, and torsion simultaneously. A prototype 4-story RC building was selected, analyzed using linear dynamic procedure and finally evaluated according to the acceptance criteria of FEM356. This building satisfies the criteria.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.376-383
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• 1996

보(beam)는 기계 구조 및 항공 우주 구조물의 기본적인 요소로서, 특히 큰 동적 거동을 하는 경우는 비선형성이 두드러지게 나타나는 것으로 알려져 있고[4], 헬리콥터의 회전날개(rotor blade)나 두께가 얇은 고속회전 축등의 경우에는 비틀림(torsion)과 굽힘(bending) 운동이 비선형 연성되어 나타나게 된다. 이러한 비선형 연성 효과를 갖는 경우에는 운동의 양상이 복잡하게 전개된다. 따라서 본 연구에서는 비선형 연성운동이 생기는 이러한 단순 외팔보에 대해 비선형 진동 특성을 파악하고 각 비틀림(internal resonance)현상[5]에 따른 정상상태 진폭 응답의 해석을 그 목적으로 한다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.87-92
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• 1989

In this study, the nonlinear dynamic model of the systems which include the offshore structure, the surrounding sea water in terms of the added mass, the foundation in terms of frequency independent springs, dashpots, and the floating ice feature with its hydrodynamic added mass, are proposed for the problem of the large ice floes impact. Dynamic Analysis is performed on two site conditions, sand site and silt site, and on two seasons, winter and summer, for various ice floe velocities. As a result of study, Ice floes from energy balenced method is lower than that from dynamic modeling on sand site, and higher than the on silt site.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.65-75
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• 1993

Presented is a method for nonstationary response analysis of an offshore guyed tower subjected to strong earthquake motions under moderate random waves and current loadings. By taking the time varying envelope function and the auto-correlation function of the ground acceleration in terms of complex exponential functions, an analytical procedure is developed for computing time varying variances of the tower response. The stationary responses due to small random waves are obtained by using frequency domain method, and the results are combined with the nonstationary results due to earthquakes. Finally, the expected maximum responses are estimated. Through the example analyses, the nonstationary method developed in this study is verified, and the contributions of the earthquake, wave and current loadings to the total maximum response are investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.171-178
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• 2008

The object of this study is to propose a rate of vibration increase in the analysis of temporary rail non-fixed in the vertical direction and characterize the nonlinear dynamic behavior of temporary rail while considering longitudinal and latitudinal load, vibration and lifting. The rate of vibration increase is proposed through measurement of an actual structure that is largely affected by loading and vibration of the superstructure. Dynamic behavior was additionally characterized by the dynamic response resulting from nonlinear dynamic finite element analysis with vehicle loading, including the rate of vibration increase. As a result, the rate of vibration increase by the vibration of an Auto Bar Machine is determined as 7% and the maximum stress in the analysis of the nonlinear rail is increased 14.5% over that of linear rail, and temporary rail is shown to be very sensitive to the velocity of the superstructure.