• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.407-417
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• 2005

An experimental and analytical study was performed to apply the friction pendulum system (FPS) to the main control room of a nuclear power plant. A friction pendulum bearing was fabricated, and the dynamic response of the bearing was evaluated. A partial model of a main control room attached to the FPS was tested on the shake table. The model consisted of a cabinet, a $3m\times3m$ access floor, and four friction pendulum bearings. The artificial time history based on the floor response spectrum of the main control room was used as the earthquake input signal in the test. Comparisons between the analytical study and the experimental study were conducted to verify the results and to extend the experimental study to the range of parameters that could not be experimentally studied.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.879-884
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• 1998

본 연구에서는 현재 국내에서 개발중인 액체금속로 KAL IMER(Korea L Iquid MEt a l Reactor)의 면진설계에 적용하기 위한 적층고무베어링의 수학적 해석모델을 개발하고자 한다. 이를 위하여 수정 비선형 Rate 모델과 특성실험 결과로 부터 구한 파라미터 특성식을 이용한 적층고무베어링의 해석모델 수립하고 이를 1자유도계 지진모델에 적용하여 히스레레틱 거동에 대한 해석적 결과와 적층고무베어링의 특성 실험결과와 비교분석하여 해석모델의 정확성을 검토하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.79-89
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• 1997

The objective of this paper is to investigate the mechanical characteristics of the laminated rubber bearings (LRBs) for the seismic isolation. The evaluations of the proposed equations of the LRB horizontal stiffness are carried out and these equations are extended to the visco-elastic problems to investigate the damping amplifications of LRBs. The stability evaluation of LRBs is also performed. For investigation of the dynamic characteristics of LRBs, the horizontal stiffness equations of the LRBs considering the P-delta effects are applied to the modeling of a seismically isolated structure and the earthquake response time history analyses are carried out. From this research, the proposed simple equation of the horizontal stiffness of LRB is so useful for the design loads and easily extended to the visco-elastic problems. Through the stability evaluation of LRB, the increasing ratio of the total rubber thickness of the LRB severely decrecises the bucking load than the increasing ratio of unit rubber thickness. From the comparison of the dynamic shear deflection of LRB, the analysis results are in good agreement with those of the experiments.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.55-61
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• 2008

One of the most recent base-isolation systems to improve the earthquake resistance of structures is the Friction Pendulum System(FPS). Simple in design but with versatile properties, the FPS has been used in some of the world s largest seismically isolated buildings, bridges and chemical tanks. FPS using PTFE(Polytetrafl-uoroethylene) based material has been developed to provide a simple and effective way for structures to achieve earthquake resistance. PTFE materials are soft, and are apt to become deformed easily after a few working cycles. In this study, magnetic force is used rather than the usual PTFE materials to improve the material shortcomings. A MF-FPS(Magnetic force-Friction Pendulum System) is proposed, and us shown to effectively protect structures against earthquakes. To demonstrate the advantages of this new system, the MF-FPS is compared with FPS as an attempt to prove its performance. A six-degree-of-freedom model is considered as a numerical example. The ground acceleration data of El Centro, Mexico and Gebze earthquakes are used as seismic excitations. The results showed that MF-FPS improved performance compared with FPS.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.448-453
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• 2001

This paper presents an analytical evaluation of the effect of motion on seismic responses of base isolated low-level building and experimental studies to evaluate isolation performances of a rubber bearing. Dynamic responses induced by earthquake were evaluated by response analyses, taking the rubber bearing of the base isolation devices into account. In the experiment, vibration tests were carried out using a model for rubber bearings as isolation devices against earthquake in order to investigate the isolation performances of the rubber bearings. Several kinds of rubber bearing for base isolated low-level building against earthquake are examined. As a result, it is shown that the effect of the motion on the response of the building and the base response is well controlled from a seismic design standpoint.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.97-105
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• 2001

Rubber bearings may exhibit a significant cold temperature effect and some velocity dependency(strain rate effect). Both of these attributes which affect non-linear behavior must be accounted for when accurately modeling the bearings behavior, therefore, an analytical models is proposed to consider the effects of the cold temperature and strain rate on both rubber and lead. From the results of an experimental investigation where the frozen bearings were tested under lateral cyclic loading with constant axial load, a non-linear system identification with least squares procedure was applied to determine the material properties of rubber and lead. It is demonstrated that the proposed analytical model is able to simulate the reversed cyclic loading behavior of elastometric and lead-rubber bearings.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.431-431
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.392-397
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• 1996

지반특성에 따라 지진발생시 면진구조물과 비면진 구조물의 응답특성이 어떠한가를 평가하기위해, 1940 El Centro 지진을 입력지진으로 하고, 면진구조물로는 가압경수형 원자로격납건물을 이용하여 수평(NS) 및 수직지진입력에 대한 시간이력해석을 수행하였다. 0.5Hz 수평면진 구조물의 경우 수평방향 가속도응답은 지반특성에 무관하게 거의 변화가 없으며, 또 2Hz 이상에서 비면진구조물의 수평지진가속도응답보다 현저히 낮은 가속도응답을 갖는다. 면진베어링의 수직방향 21Hz 고유진동수는 풍화암의 경우 수직방향 가속도응답에 영향을 주지 않으나. 경암의 경우 원자로지지점에서의 수직방향 가속도응답을 전반적으로 증가시킨다. 비면진 구조물의 경우 지반의 강성이 약할수록 가속도응답이 비교적 큰 폴라크레인위치에서 수평 및 수직방향 가속도응답이 감소되는 것으로 나타났으며, 특히 수직방향의 가속도응답이 크게 감소하는 것으로 나타났다.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.275-280
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• 2001

Seismic isolator system is one of the most widely used base isolation system in order to control the vibration of structure against earthquake excitation. The evaluation of vulcanization time in molding the rubber bearing is very important for both proper ability of isolator and efficiency of manufacture. This paper deals with experimental measurement of temperature of isolator with senor inside in it, and compared with the result of FEA in order to evaluate the vulcanization time. Properties of rubber bearing which is used in the FEA are obtained by controlling the specific heat of rubber. With the obtained properties of rubber, the isolator is analysed by FEA. As a result, an appropriate analytical vulcanization time is obtained. This time is regarded as an appropriate temperature, which is used to effective manufacture.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.221-230
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• 2004

In this paper, the dynamic response of a multi-story steel moment resisting frame equipped with viscoelastic dampers or lead rubber bearing type isolators subjected to seismic loads is investigated analytically. The objective of this study is to find the best location of viscoelastic dampers by the maximum stress method and maximum story drifts method from structure analysis. Also, a secondary objective of the study is to compare the member force, combined stress, and natural period of the structure retrofitted with viscoelastic dampers or lead rubber bearing type isolators to find effective vibration control method.