Effect on Rocking Vibration Due to Characteristics Uncertainty of Three-Dimensional Seismic Isolation System

This paper describes three-dimensional isolation performance of seismic isolation system using air bearings. Long period seismic waves having predominant period of from a few seconds to a few ten seconds have recently been observed in various earthquakes. Also resonances of high-rise buildings and sloshing of petroleum tanks in consequence of long period seismic waves have been reported. Therefore the isolation systems having very long natural period or no natural period are required. In a previous paper [1], we proposed an isolation system having no natural period by using air bearings. Additionally we have already reported an introduction of the system, and have investigated horizontal motion during earthquake in the previous paper. It was confirmed by horizontal vibration experiment and simulation in the previous paper that the proposed system had good performance of isolation. However vertical motion should be investigated, because vertical motion varies horizontal frictional force. Therefore this paper describes investigation regarding vertical motion of the proposed system by experiment. At first, a vertical excitation test of the system is carried out so as to investigate vertical dynamic property. Then a three-dimensional vibration test using seismic waves is carried out so as to investigate performance of isolation against three-dimensional seismic waves.

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Three Dimensional Seismic Isolation System Using Hydraulic Cylinder

Seismic Engineering, Volume 2 ◽

10.1115/pvp2002-1429 ◽

2002 ◽

Author(s):

Shinichiro Kajii ◽

Naoki Sawa ◽

Nobuhiro Kunitake ◽

K. Umeki

Keyword(s):

Seismic Isolation ◽

Three Dimensional ◽

Vertical Direction ◽

Hydraulic Cylinder ◽

Seismic Load ◽

3D Seismic ◽

Isolation System ◽

Response Characteristics ◽

Seismic Motion ◽

Hydraulic Cylinders

A three-dimensional (3D) seismic isolation system for FBR building is under development. The proposed vertical isolation system consists form hydraulic cylinders with water-based liquid and accumulators to support large vertical static load and to realize low natural frequency in the vertical direction. For horizontal isolation, laminated rubber isolator or sliding type isolator will be combined. Because the major part of the feasibility of this isolation system depends on the sealing function and durability of the hydraulic cylinder, a series of feasibility tests of the hydraulic cylinder have been conducted to verify the reliability against seismic load and seismic motion. This paper describes the specification of the seismic isolations system, seismic response characteristics and the results of the feasibility tests of the seal. This study was performed as part of a government sponsored R&D project on 3D seismic isolation.

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Study on Three-Dimensional Seismic Isolation System for Next Generation Nuclear Power Plant: Independent Cable Reinforced Rolling-Seal Air Spring

Seismic Engineering, Volume 1 ◽

10.1115/pvp2004-2933 ◽

2004 ◽

Cited By ~ 4

Author(s):

Mitsuru Kageyama ◽

Yoshihiko Hino ◽

Satoshi Moro

Keyword(s):

Power Plant ◽

Nuclear Power ◽

Seismic Isolation ◽

Base Isolation ◽

Three Dimensional ◽

Outer Diameter ◽

Next Generation ◽

Air Spring ◽

Isolation System ◽

Rubber Sheet

In Japan, the development of the next generation NPP has been conducted in recent years. In the equipment/piping design of the plant, seismic condition has been required much more mitigate than before. So, the three-dimensional (abbreviation to 3D) seismic isolation system development has also been conducted since 2000. The superlative 3D base isolation system for the entire building was proposed. The system is composed of cable reinforced air springs, rocking arresters and viscous dampers. Dimensions of the air spring applied to the actual power plant are 8 meters in the outer-diameter and 3.5 meters in height. The allowable half strokes are 1.0 meters in horizontal and 0.5 meters in vertical respectively. The maximum supporting weight for a single device is 70 MN. The inner design air pressure is about 1.8MPa. This air spring has a distinguishing feature, which realizes 3D base isolation with a single device, whose natural periods are about 4 seconds in horizontal and about 3 seconds in vertical. In order to verify the 3D performance of this system, several feasibility tests were conducted. Firstly, 3D shaking table tests were conducted. The test specimen is scaled 1/4 of the actual device. The outer diameter and inner air pressure of air spring is 2 meters and 0.164 MPa. Next, a pressure resistant test for the sub cable, textile sheet and rubber sheet, which composed air spring, were conducted as a full scale model test. Then, air permeation test for the rubber sheet was also conducted. As a result, the proposed system was verified that it could be applied to the actual nuclear power plants.

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A liquid spring–magnetorheological damper system under combined axial and shear loading for three-dimensional seismic isolation of structures

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18783090 ◽

2018 ◽

Vol 29 (18) ◽

pp. 3517-3532 ◽

Cited By ~ 7

Author(s):

Sevki Cesmeci ◽

Faramarz Gordaninejad ◽

Keri L Ryan ◽

Walaa Eltahawy

Keyword(s):

Seismic Isolation ◽

Theoretical Calculations ◽

Three Dimensional ◽

Real Life ◽

Vertical Component ◽

Axial Loading ◽

Shear Loading ◽

Magnetorheological Damper ◽

Isolation System ◽

Fail Safe

This study focuses on experimental investigation of a fail-safe, bi-linear, liquid spring magnetorheological damper system for a three-dimensional earthquake isolation system. The device combines the controllable magnetorheological damping, fail-safe viscous damping, and liquid spring features in a single unit serving as the vertical component of a building isolation system. The bi-linear liquid spring feature provides two different stiffnesses in compression and rebound modes. The higher stiffness in the rebound mode prevents a possible overturning of the structure during rocking mode. For practical application, the device is to be stacked together along with the traditional elastomeric bearings that are currently used to absorb the horizontal ground excitations. An experimental setup is designed to reflect the real-life loading conditions. The 1/4th-scale device is exposed to combined dynamic axial loading (reflecting vertical seismic excitation) and constant shear force that are up to 245 and 28 kN, respectively. The results demonstrate that the device performs successfully under the combined axial and shear loadings and compare well with the theoretical calculations.

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Three Dimensional Seismic Isolation System for Next-Generation Nuclear Power Plant With Rolling Seal Type Air Spring and Hydraulic Rocking Suppression System

Volume 8: Seismic Engineering ◽

10.1115/pvp2005-71376 ◽

2005 ◽

Cited By ~ 6

Author(s):

Takahiro Shimada ◽

Junji Suhara ◽

Kazuhiko Inoue

Keyword(s):

Dynamic Loading ◽

Nuclear Power ◽

Seismic Isolation ◽

Base Isolation ◽

Three Dimensional ◽

Loading Test ◽

Isolation System ◽

Ability Test ◽

Base Isolation System ◽

Suppression System

Three dimensional (3D) seismic isolation devices have been developed to use for the base isolation system of the heavy building like a nuclear reactor building. The developed seismic isolation system is composed of rolling seal type air springs and the hydraulic type springs with rocking suppression system for vertical base isolation device. In horizontal direction, the same laminated rubber bearings are used as horizontal isolation device for these systems. The performances and the applicability have already been evaluated by the technical feasibility tests and performance tests for each system. In this study, it was evaluated that the performance of the 3D base isolation system with rolling seal type air springs combined with hydraulic rocking suppression devices. A 1/7 scaled model of the 3D base isolation devices were manufactured and some performance test were executed for each device. For the rolling seal type air springs, dynamic loading test was executed with a vibration table, and pressure resistant ability test was executed for reinforced air springs. In the dynamic loading test, it is confirmed that the natural period and damping performance were verified. In the pressure resistant ability test, it is confirmed that the air springs had sufficient strength. For the hydraulic rocking suppression system, forced dynamic loading test was carried out in order to measure the frictional and oil flow resistance force on each cylinder. And the vibration table tests were carried out with supported weight of 228 MN in order to evaluate and to confirm the horizontal and vertical isolation performance, rocking suppression performance, and the applicability of the this seismic isolation system as the combined system. 4 rolling seal type air springs and 4 hydraulic load-carrying cylinders with rocking suppression devices supported the weight. As a result, the proposed system was verified that it could be applied to the actual nuclear power plant building to be target.

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