• Title/Summary/Keyword: Base-Isolation

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Response Control of Structure by Frictional Base Isolation System : Rigid-Mass Model (마찰지진격리장치와 구조물의 응답제어: 강체질량모델에서의 적용)

  • 김재관;이원주;김영중;김병현
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.04a
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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.

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Seismic Response Analysis of Rectangular Tank with Base-Isolation System (구형 면진유체저장조의 지진시 거동해석)

  • 전영선;최인길;황신일;김진웅
    • Computational Structural Engineering
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    • v.8 no.1
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    • pp.107-113
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    • 1995
  • Spent fuel storage pool should maintain its structural integrity and the safety of stored spent fuels against design earthquake load. In this study, the seismic response analysis of the pool with LRB isolation system is performed for two different earthquakes. To investigate the seismic response of the base isolated pool, the analysis results are compared with the responses of conventional type. In conclusion, the base-isolation system is effective to reduce the seismic forces transmitted to the superstructure and the responses, and to secure the safety of the storage pool and stored spent fuel.

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A Study on Base Isolation Performance of MR Dampers Using Clipped-Optimal Control (Clipped-Optimal Control을 사용한 MR 감쇠기의 면진성능에 관한 연구)

  • 고봉준;이종세
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.529-536
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    • 2003
  • As large structures such as high-rise buildings and cable-stayed bridges become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a method to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, the seismic performance of MR dampers are studied and compared with that of the NZ system as a base isolation system. As the control algorithm of the MR damper, the clipped-optimal control(applied LQR method) is employed. A five-story building is modeled and the seismic performance of the two systems subjected to three different earthquakes is compared. The results show that the MR damper system can provide superior protection than the NZ system for a wide range of ground motions.

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Development of Computer Program for Seismic Response Analysis of Base Isolated Structures (면진 구조물의 지진응답 해석 프로그램 개발)

  • 정정훈;허영철;김병현
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.09a
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    • pp.348-355
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    • 2001
  • A computer program named \"NLDA-BIS\", which runs under the MATLAB environment, is developed fur seismic response analysis of base isolated structures. This program can explicitly model the various nonlinear isolation elements such as elastomeric bearings, sliding bearings and general viscous dampers, and so on. Newmark'\`s constant average acceleration method fur calculating the responses in time domain and the iterative pseudo-force method for treating the nonlinear isolation forces are adopted. For capturing the hysteretic behavior of isolation elements, the modified Wen's equations are adopted and solved by the numerical differentiation formula method. To verify the validity of the developed program, the seismic responses of a six-story reinforced concrete base isolated structure are calculated and compared with results obtained by the program \"3D-BASIS\" developed at the State University of New York at Buffalo which is the most widely used code far analyzing isolated structures today.ed structures today.

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An Experimental Study on the Characteristics of Steel Hysteretic Dampers with Pin-type Elements (실험을 통한 핀타입(pin-type) 강재이력댐퍼의 거동특성연구)

  • 강형택;김인배;이일근;정진혁
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.257-262
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    • 2003
  • Base isolation bearings are known as an effective system to Protect bridges from the earthquake damage. There are many types of base isolation bearings in the market. Among them, steel hysteretic damper, made of mild steel and one of the oldest ones, has some good features. Since steel hysteretic damper is made of steel and has simple structure, it is cheeper and easier to maintain than other types. Despite the advantages, steel hysteretic damper with pin-type elements has no application in Korea. The steel hysteretic damper with pin-type elements are tested to examin the basic characteristics and to evaluate antiseismic performance. In this paper, the results of the test are presented.

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Base-isolated building with high-damping spring system subjected to near fault earthquakes

  • Tornello, Miguel Eduardo;Sarrazin, Mauricio
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.315-340
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    • 2012
  • There are many types of seismic isolation devices that are being used today for structural control of earthquake response in buildings. The most commonly used are sliding bearings and elastomeric bearings, the latter with or without lead core. An alternative solution is the use of steel springs combined with viscoelastic fluid dampers, which is the case discussed in this paper. An analytical study of a three-story building supported on helical steel springs and viscoelastic fluid dampers, GERB Control System (GCS), subjected to near-fault earthquakes is presented. Several earthquakes records have been obtained by the acceleration network installed in the isolated building and in its non-isolated twin since they were finished. These experimental results are analysed and discussed. The aim is to show that the spring-based system can be an alternative for base isolation of small building located near active faults.

Seismic analysis and modeling of isolated elevated liquid storage tanks

  • Seleemah, Ayman A.;El-Sharkawy, Mohamed
    • Earthquakes and Structures
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    • v.2 no.4
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    • pp.397-412
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    • 2011
  • In this paper, the seismic response of elevated broad and slender liquid storage tanks isolated by elastomeric or sliding bearings was investigated. The accuracy of predictions of SAP2000 vs. 3D-BASIS-ME programs was examined. A comparative study of the performance of base isolated tanks when isolation bearings are placed at the top or at the bottom of the supporting tower structure was conducted. It was found that base isolation is quite effective in reducing the earthquake response of elevated liquid storage tanks in which high reductions of base shear and shaft displacement were achieved. Modeling the isolated tanks in SAP2000 was very successful in producing results that are nearly identical to those of program 3D-BASIS-ME. Placing the isolators at the top of the shaft in elevated tanks proved to be much better than placing them at the bottom.

Feasibility Study for Seismic Performance Enhancement of NPP Based on Equipment Base Isolation (기기면진 기반 원전 내진성능 상향 타당성 검토)

  • Lee, Jin Hyeong;Shin, Tae Myung;Koo, Gyeong Hoi
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.14 no.2
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    • pp.88-95
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    • 2018
  • In this study, to enhance the seismic performance of nuclear power plants (NPP), a small laminated rubber bearing (LRB) is chosen as a seismic design option of the vulnerable equipment. Prior to the application of equipment base isolation, it is necessary to review the feasibility that the technique contributes enough to the seismic performance of NPP by analysis. At first, some preliminary design of small LRBs for equipment is carried out. Design parameters such as horizontal and vertical stiffnesses, design natural frequencies are checked by calculation and analysis for the four design options considering various upper weights. Performance test of small LRB is to be carried out to verify static performance using the results.

A State-Space Transient Response Analysis of Rotor-Bearing System with Base Excitation (기초가진 로터-베어링 시스템의 상태공간 과도응답해석)

  • 이안성;김병옥;김영철;김영춘
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.669-674
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    • 2004
  • In this study, the analytical method to evaluate the response of rotor-bearing system subjected to base excitation was presented. The equations of motion contain speed dependent gyroscopic terms, base rotation dependent parametric terms and several forcing function terms which depend on linear accelerations, rotational accelerations and a combination of linear and rotational combination. The study of rotor-bearing system excited by its base motion is not only able to predict the rotational performance, but provides the fundamental data for vibration isolation. In order to illustrate transient response, transient response analysis of a practical application sample were performed. The transient response was carried out for the given base excitation by using the state-space Newmark method that incorporates the average velocity concept.

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Rubber bearing isolation for structures prone to earthquake - a cost effectiveness analysis

  • Islam, A.B.M. Saiful;Sodangi, Mahmoud
    • Earthquakes and Structures
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    • v.19 no.4
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    • pp.261-272
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    • 2020
  • Recent severe earthquakes in and around the vital public places worldwide indicate the severe vulnerability of ground excitation to be assailed. Reducing the effect of seismic lateral load in structural design is an important conception. Essentially, seismic isolation is required to shield the superstructure in such a way that the building superstructure would not move when the ground is shaking. This study explores the effectiveness, design, and practical feasibility of base isolation systems to reduce seismic demands on buildings of varying elevations. Thus, static and dynamic analyses were conducted based on site-specific bi-directional earthquakes for base-isolated as well as fixed-based buildings. Remarkably, it was discovered that isolators used in low-rise to high-rise structures tend to significantly decrease the structural responses of seismic prone buildings. The higher allowable horizontal displacement induces structural flexibility and ensure good structural health of the building stories. Reinforcement from vertical and horizontal members can be reduced in significant amounts for BI buildings. Thus, although incorporating base isolators increases the initial outlay, it considerably diminishes the total structural cost.