• Structural Engineering and Mechanics
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• 제40권4호
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• pp.453-469
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• 2011

A one-story, wooden-frame, intermediate-bay model with Dou-Gon designed according to the Building Standards of the Song Dynasty (A.D.960-1279), was tested on a unidirectional shaking table. The main objectives of this experimental study were to investigate the seismic performance of Chinese historic wooden structure under various base input intensities. El Centro wave (N-S), Taft wave and Lanzhou wave were selected as input excitations. 27 seismic geophones were instrumented to measure the real-time displacement, velocity and acceleration respectively. Dynamic characteristics, failure mode and hysteretic energy dissipation performance of the model are analyzed. Test results indicate that the nature period and damping ratio of the model increase with the increasing magnitude of earthquake excitation. The nature period of the model is within 0.5~0.6 s, the damping ratio is 3~4%. The maximum acceleration dynamic magnification factor is less than 1 and decreases as the input seismic power increases. The frictional slippage of Dou-Gon layers (corbel brackets) between beams and plates dissipates a certain amount of seismic energy, and so does the slippage between posts and plinths. The mortise-tenon joint of the timber frame dissipates most of the seismic energy. Therefore, it plays a significant part in shock absorption and isolation.

• Earthquakes and Structures
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• 제9권5호
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• pp.1029-1044
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• 2015

To investigate the seismic pounding response of long-span bridges with high-piers under strong ground motions, shaking table tests were performed on a 1/10-scaled bridge model consisting of three continuous spans with rigid frames and one simply-supported span. The seismic pounding responses of this bridge model under different earthquake excitations including the uniform excitation and the traveling wave excitations were experimentally studied. The influence of dampers to the seismic pounding effects at the expansion joints was analyzed through nonlinear dynamic analyses in this research. The seismic pounding effects obtained from numerical analyses of the bridge model are in favorable agreement with the experimental results. Seismic pounding effect of bridge superstructures is dependent on the structural dynamic properties of the adjacent spans and characteristics of ground motions. Moreover, supplemental damping can effectively mitigate pounding effects of the bridge superstructures, and reduce the base shear forces of the bridge piers.

• 대한토목학회논문집
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• 제31권4A호
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• pp.303-309
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• 2011

적층고무받침은 지진격리 교량에서 면진장치로 주로 사용되고 있으며, 지진격리 설계시 적층고무받침의 성능 및 거동특성을 파악하는 것은 매우 중요하다. 적층고무받침의 주요 평가요소로는 압축 및 전단특성 그리고 인장특성으로 구분된다. 이 요소 중 압축특성 및 전단특성에 대한 특성실험 결과는 많으나, 인장특성에 대한 자료는 충분하지 않다. 이에 따라 본 연구에서는 인장하중을 받는 적층형 고무받침의 특성에 대해 연구를 수행하였다. 적층고무받침의 인장시험은 형상계수 및 전단변형 변화에 따른 기계적 특성에 대하여 검토하였다. 실험결과 인장변형이 증가 할수록 인장이력곡선은 비선형 특성을 보이며, 단순인장시험결과 300%이상 인장변형 후 파괴되었다. 반면에 전단변형된 상태에서 인장파괴는 약 40%이상의 인장변형 후 파괴되었다. 또한 형상계수가 낮을수록 극한인장 파괴성능이 저하되었다. 이와 같은 결과는 명확하지는 않지만 고무 층이 3축 인장 받을 경우 내부공극에 의해 균열이 확장되어 파괴가 발생하는 것으로 추측된다. 본 연구결과는 지진격리 구조물 설계시 인장하중에 대한 기초자료로 충분히 활용 가능할 것으로 판단된다.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.57-71
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• 2015

This study investigates the feasibility of retrofitting an existing building by connecting the existing building to a new building using connecting dampers. The new building is base-isolated and viscoelastic dampers are assigned as connecting dampers. Scaled models are tested under three different earthquake records using a shaking table. The existing building and the new building are 9 and 8 stories respectively. The existing building model shows more than 3% increase in damping ratio. The maximum dynamic responses and the root mean square responses of the existing building model to earthquakes are substantially reduced by at least 20% and 59% respectively. Further, numerical models are developed by conducting time-history analysis to predict the performance of the proposed seismic mitigation system. The predictions agree well with the test results. Numerical simulations are carried out to optimize the properties of connecting dampers and base isolators. It is demonstrated that more than 50% of the peak responses can be reduced by properly adjusting the properties of connecting dampers and base isolators.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.426-431
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• 2001

Seismic performance of base isolated rigid-mass model were studied through shaking table tests. Friction pendulum systems (FPS), pure-friction systems with laminated rubber bearing (LRB) were selected for the comparison of performance. Performance of specially designed isolation systems were tested statically using actuator and dynamically using shaking table. Numerical methods were developed to simulate the nonlinear behavior of the frictional base isolation systems. Two models were considered. one is modified Bouc-Wen model considering breakaway coefficient of friction and the other is classical Coulomb model. The results of numerical methods are found to be in very good agreement with test results.

• 한국지진공학회논문집
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• 제13권1호
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• pp.53-60
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• 2009

지진격리 구조물은 하부구조에서 상부구조로 전달되는 지진력의 현저한 감소가 요구되는 경우 고감쇠 고무받침(HDRB)과 같은 지진격리받침을 사용하는 구조물로서 내진설계의 도입 이후부터 많이 설계, 시공되고 있다. 적층고무받침은 지진격리장치에서 가장 중요한 구조부재이다. 적층형 고무받침의 기본 특성은 압축시험, 압축전단시험, 크리프시험 등을 통하여 얻는 것이 일반적이다. 본 연구에서는 축 응력 7.5MPa, 8.37MPa인 지진격리받침(고감쇠 고무받침)을 실물크기로 제작하여 실험실에서 1000시간동안 크리프 시험을 실시하였다. 고감쇠 고무받침과 같은 지진격리받침을 실제 교량환경 상태에서 장기간 압축 크리프 시험한 결과 1000시간 후 최대크리프 변형은 전체 고무두께의 $0.3{\sim}1.92%$로 변형하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.949-952
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• 2005

According to the national space program in Korea, is satellites will be launch into space up to 2015. Especially, KARI is going to develope of its own a high resolution camera of less than 1m to be mounted on next Multipurpose Satellite. When performing testing of large spacecraft or hardware that will be launched into orbit, it is necessary to conduct a testing with space-simulated environment. To achieve this requirement, thermal vacuum chamber is generally used. KARI has been developed a very Large Thermal Vacuum Chamber(LTVC) from 2003 to accomodate future space program, such as KOMPSAT, COMS, and Launch vehicles. This new facility will be used to qualify the first self developed High Resolution Camera, which will be loaded on KOMPSAT-3. To perform an optical test for space camera, it is necessary to provide vibration free environment. Thus the vibration responses on the optical table due to external vibration should be minimized by using a special isolation system. In this paper, we propose the concept design of vibration isolation system for the development of the high resolution camera.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.473-480
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• 2003

In these days, The base isolation system is often used improve the seismic capacity of the structure Instead of conventional techniques of strengthening the structural members. The purpose of this study is to evaluate dynamic property evaluation of control equipment using Lead Rubber Bearing. In this study, analysis numerical was performed to determine the optimal dynamic property of lead rubber bearing and damper which minimize the response of base from in main control room. Also the analytical results was composed with the test results peformed in previous study

• 한국산학기술학회논문지
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• 제17권4호
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• pp.52-58
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• 2016

최근 빈번한 지진발생으로 인한 구조물에 대한 안전성에 대한 관심이 증대하는 가운데 면진시스템은 신축 구조물뿐만 아니라 기존 구조물에 대해서도 구조물 자체의 기능이나 미관을 손상시키지 않고 효과적으로 내진성능을 향상시킬 수 있는 방법이며, 지진을 경험한 외국에서 이미 그 효율성이 입증된 방법이다. 본 연구에서는 스테인리스 물탱크를 대상으로 지진에 대한 안전성 확보를 위해 천연고무받침(NRB)을 이용한 면진시스템을 제안하였다. 이에 대해 비면진 물탱크와 천연고무받침이 설치된 물탱크의 내진성능을 평가하기 위해 진동대 실험을 실시하였다. 물탱크에 변위계를 설치한 후 0.0m, 1.5m, 2.5m 수위별로 인공지진파 0.154g, 0.231g, 0.341g, 0.348g를 가진하여 비면진 물탱크와 천연고무받침이 설치된 물탱크에 거동 특성을 비교 분석하였다. 진동대 실험 결과 수위 2.5m의 경우 면진 물탱크에서 전반적으로 면진시스템의 감쇠효과가 나타나지만, 수위 0.0m, 1.5m의 경우 비면진 물탱크보다 면진 물탱크에서 큰 변위가 발생하는 것으로 나타났다. 이는 물탱크 수위에 따른 중량이 면진시스템의 감쇠효과에 영향을 미치는 것으로 판단되며 면진시스템을 이용하여 물탱크의 내진 보강을 할 경우 유체의 저장 수위에 따라 지진격리받침을 설계해야 할 것으로 판단된다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.391-398
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• 2000

To evaluate the seismic performance of a base isolated building accurate analytical model should be selected. The analytical results such as reduced accelerations member forces and relative displacements of the superstructure of the base isolated building are only meaningful when the analytical model is close enough to the real structure. Real size one bay-two story steel frame and two kinds of seismic isolators(laminated elastomeric bearing and lead-rubber bearing) are designed. manufactured and constructed in the laboratory. Free vibration tests using fuse bars were conducted to evaluate the change of dynamic characteristics(period and damping) before and after base isolation of the steel frame. The experimental results of free vibration tests were also used as a bench mark for adjusting the selected analytical modeling to real base isolated steel frame.