• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.544-551
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• 2005

This paper investigates the effectiveness of the MR damper-based control systems for seismic protection of base isolated building sturcutres employing some semiactive control algorithms, such as the modified clipped-optimal control, the maximum energy dissipation, and the modulated homogeneous friction, by examining the Phase I smart base isolated benchmark building problem. The results of the numerical simulations showed that most of the control systems considered herein could be beneficial in reducing seismic responses, especially base displacement or isolator deformation, of base isolated building structures. It is also verified that another version of the modified clipped-optimal control algorithm proposed in this study and the modulated homogeneous friction algorithm are more effective than other semiactive control algorithms.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.178-185
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• 1999

Minimum life-cycle cost helps to evaluate cost effectiveness of base-isolated bridges under specific condition. Life-cycle cost mainly consists of the initial construction cost and the expected damage cost. Damage cost estimation needs proper model of input ground motion failure probability evaluation method and limit states definition. We model the input ground motion as spectral density function compatible with the response spectra defined at each seismicity and site condition. Spectrum analysis and crossing theory is suitable for reseating calculation of failure probabilities in the process of cost minimization. Limit states of base-isolated bridges re defined for superstructure isolator and pier respectively The method is applied to both base-isolated bridges and conventional bridges under the same conditions to investigate cost effectiveness of base isolation in low and moderate seismic region. the results show that base-isolation of bridges are more effective in low and moderate seismic region and that the site effects on the economical efficiency may not be negligible in such a region.

• 한국기계가공학회지
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• 제19권6호
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• pp.23-28
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• 2020

A non-linear vibration isolation system composed of a non-linear spring and a linear damper was presented in a previous study. The advantage of the proposed isolator is the simple structure of the system. When the base of the isolator is harmonically excited, the response component of the mass at the excitation frequency was approximated using three different methods: linear approximation, harmonic balance, and higher-order frequency response functions (FRFs). The method using higher-order FRFs produces significantly more accurate results compared with the other methods. The error between the exact and approximate responses does not increase monotonously with the excitation amplitude and is less than 2%.

• Earthquakes and Structures
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• 제13권6호
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• pp.561-572
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• 2017

Seismic base isolation has been accepted as one of the most popular design procedures to protect important structures against earthquakes. However, due to lack of information and experimental data the application of base isolation is quite limited to nuclear power plant (NPP) industry. Moreover, the effects of inelastic behavior of soil beneath base-isolated NPP have raised questions to the effectiveness of isolation device. This study applies the wavelet analysis to investigate the effects of soil-structure interaction (SSI) on the seismic response of a base-isolated NPP structure. To evaluate the SSI effects, the NPP structure is modelled as a lumped mass stick model and combined with a soil model using the concept of cone models. The lead rubber bearing (LRB) base isolator is used to adopt the base isolation system. The shear wave velocity of soil is varied to reflect the real rock site conditions of structure. The comparison between seismic performance of isolated structure and non-isolated structure has drawn. The results show that the wavelet analysis proves to be an efficient tool to evaluate the SSI effects on the seismic response of base-isolated structure and the seismic performance of base-isolated NPP is not sensitive to the effects in this case.

• 대한토목학회논문집
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• 제13권4호
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• pp.51-64
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• 1993

본 연구에서는 원통형 액체저장탱크(cylindrical liquid storage tank)를 대상으로 적층(積層)고무받침(LRB)방식의 기초분리장치(base isolator)를 사용하였을 때의 진동감소효과를 분석하기 위하여 지진하중에 대한 유사동적실험(Pseudo-dynamic test)을 수행하였다. 유사동적실험을 효과적으로 수행하기 위하여 구조분할기법(substructuring technique)을 도입하여 액체저장탱크를 수치적으로 모형화하였으며 효율적인 수치적분방법을 실험알고리즘에 적용하였다.

• Geomechanics and Engineering
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• 제7권1호
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.61-70
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• 2005

본 연구에서는 하이브리드 면진장치가 설치된 단자유도 구조물에 대하여 진동대 실험을 수행하였다. 본 연구에서 사용된 하이브리드 면진장치는 네 개의 FPS와 한 개의 MR 감쇠기로 구성하였다. 다양한 크기 및 특성을 가진 지진하중을 하이브리드 면진장치가 설치된 구조물에 가하여 진동제어 성능을 평가하였다. 본 연구에는 준능동 MR 감쇠기의 저항력을 효과적으로 조절하기 위하여 퍼지제어기를 사용하였고 구조물에 부착된 계측기를 통하여 변위 및 가속도를 피드백으로 이용한다. 수동 및 준능동 제어기법을 사용하여 얻은 구조물의 응답을 서로 비교하였고 그 결과 FPS와 MR 감쇠기의 조합으로 다양한 특성의 하중을 받는 구조물의 진동제어를 효과적으로 수행할 수 있음을 알 수 있다.

• Earthquakes and Structures
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• 제12권1호
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• pp.35-45
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• 2017

The current paper investigates the effect of the seismic pounding of neighboring buildings on the response of structures isolated by Triple Friction Pendulum Bearing (TFPB). To this end, a symmetric three-dimensional single story building is modeled for analysis with two specified levels of top deck and base deck, to capture the seismic response of the base isolators and building's roof. Linear elastic springs with different level of gaps are employed to calculate the impact between the buildings. Nonlinear Dynamic Time History Analyses (NDTHA) are conducted for seismic evaluation. Also, five different sizes with four different sets of friction coefficients are assumed for base isolators to cover a whole range of base isolation systems with various geometry configurations and fundamental period. The results are investigated in terms of base shear, buildings' drift and top deck acceleration of the superstructure. The results also indicate the profound effect of the stiffness of the adjacent buildings on the value of the impact they impose to the superstructure. Also, in situations of potential pounding, the increment of the fundamental period of the TFPB base isolator could intensify the impact force up to nearly five-fold.

• ETRI Journal
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• 제39권3호
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• pp.383-389
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• 2017

A small dual-polarized base station antenna with a simple isolation patch is presented. A high isolation is achieved when using a shorted metallic isolation patch. The experimental results indicate that the measured impedance bandwidth of the proposed antenna is 1.72 GHz to 1.89 GHz for small cell systems and that the isolation is more than 30 dB. The proposed antenna exhibits good radiation patterns with a peak gain of 8 dBi.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.136-143
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• 1997

본 연구에서는 철골구조물을 대상으로 지진격리(Base-Isolation)를 사용하였을 때의 진동감소 효과를 분석하기 위하여 지진하중에 대한 진동대 실험을 수행하였다. 실험 대상구조물은 $\frac{1}{4}$축소모형의 3층 철골구조물이며, 입력지진은 여러 계측기록과 UBC 설계스펙트럼으로부터 3가지 지반조건에 대하여 작성한 인공지진기록을 사용하였다. 축소 실험모형은 기초가 고정된 일반적인 철골구조물과 적층고무받침(Laminated Rubber Bearing) 형식의 지진격리장치(Base Isolator)를 사용한 구조물을 동시에 설치하여 그 지진응답을 비교 관찰하였다. 대부분의 하중하에서 지진격리장치가 사용된 철골구조물의 경우에 지진응답이 현저히 감소하는 것을 알 수 있으나, 장주기파의 성분이 강한 지반운동에 대해서는 오히려 지진응답이 증가하였다. 그러나 여러 지반조건에 대하여 UBC 시방서에서 규정한 설계하중에 대하여는 진동감소효과가 우수함을 보인다.