GENES4/ANP2003, Sep. 15-19, 2003, Kyoto, JAPANPaper 1195

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3D Seismic Isolation for Advanced N.P.P Application-Development of Three-Dimensional Base Isolation System with

Cable Reinforcing Air Spring-

Mitsuru KAGEYAMA1, Tsutomu IBA2, Katsuhiko UMEKI2*, Takahiro SOMAKI2, Satoshi MORO3,Masaki MORISHITA4

1Obayashi Corporation Technical Research Institute, Kiyose-shi, Tokyo 204-8558, Japan2Obayashi Corporation Engineering Department Nuclear Facilities Division, Sumida-ku, Tokyo 131-8510,

Japan3The Japan Atomic Power Company, Chiyoda-ku, Tokyo 101-0053, Japan

4Japan Nuclear Cycle Development Institute, O-arai, Ibaraki 311-1393, Japan

In Japan, the study on the development of a three-dimensional base isolation system to be applied to acommercialized FBR plant, which requires the supreme safety for equipment/piping systems against severeearthquakes, has been carried out since 2000. The system is also expected to reduce the construction costcompared with existing two-dimensional base isolation systems. Furthermore, it is also expected toestablish a site-free three-dimensional base isolation system design standard for nuclear power plants.

An idea with the concept of a cable reinforcing air spring was proposed as the three-dimensional baseisolation device. The dimension of the air spring applying to the actual nuclear power plant is 8 meters inouter-diameter and 3.5 meters in height. The allowable half strokes are 1.0 meters in horizontal directionand 0.5 meters in vertical direction, respectively. The supporting weight for a single device is 52MN, wherethe inner air pressure is about 1.4MPa.

This device enables to realize three-dimensional base isolation with a single device, whose naturalperiods are about 4 seconds in horizontal and about 3 seconds in vertical. Furthermore, this device does notrequire precise mechanical parts but just common building materials, which are steel, cable wire, polyesterfabric and a rubber sheet. So, the construction cost for this device could be on the inexpensive level.

KEYWORDS: three-dimensional seismic isolation system, cable-reinforcing air spring, shaking tabletest, simulation analysis, FBR, applicability to actual NPP plants

I. IntroductionIn Japan, studies on application of two-dimensional

base isolation systems to FBR (Fast Breeder Reactor) orPWR (Pressurized Light Water Reactor) plants have beencontinuing for about 15 years. The technical guideline forthe horizontal base isolated nuclear power plants waspublished in 2001. The aims at applying the base isolationsystem for nuclear power plants are to establish a site-freedesign standard for nuclear power plants, free from seismicdesign bindings, and to reduce the construction cost.

Since the two-dimensional isolation system (horizontalisolation) enables a considerable reduction onequipment/piping responses in the horizontal direction,compared with non-isolated conventional buildings, thethickness of structural walls besides the neutron shield canbe reduced to achieve the reduction in construction cost.However the vertical responses of the equipment/piping inthe horizontal base isolated buildings tend to be greater thanin the non-isolated conventional buildings due toamplification in the isolation layer and in the superstructure.Therefore the reinforcement of vertical seismic supports forequipment/piping is required depending on the seismicconditions in site. The development of the three-dimensional

isolation system is expected from the viewpoint of achievingfurther cost reduction in constructing nuclear power plants. The superlative three-dimensional base isolationsystem for the entire building is proposed. The system iscomposed of cable reinforcing air springs, rockingprevention devices and dampers. The dimension of the airspring applying to the actual power plant is 8 meters in theouter-diameter and 3.5 meters in height. The allowable halfstrokes are respectively 1.0 meters for the horizontaldirection and 0.5 meters for the vertical direction. Thesupporting weight for a single device is 52MN, where theinner air pressure is about 1.4ＭPa. This air spring enables torealize three-dimensional base isolation with a single device,whose natural periods are about 4 seconds in the horizontaldirection and about 3 seconds in the vertical direction.

Furthermore, this air spring does not require precisemechanical parts but just common building materials, whichare steel, cable wire, polyester fabric and a rubber sheet.Therefore, the manufacturing cost for this device could beon the inexpensive level.

In order to confirm the performance of this proposalsystem, experimental tests using the three dimensionalshaking table were carried out. The test specimen is 1/4

* Corresponding author, Tel. +81-3-5247-8552, Fax. +81-3-5247-8683, E-mail: umeki.katsuhiko@obayashi.co.jp

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scale of the actual size. The outer diameter and inner airpressure of air spring is 2 meters and 0.25MPa, respectively.So the supporting weight of air spring is approximately0.4MN including a 4-story steel frame.

As a result, the proposed system was confirmed tobehave smoothly in three directions with natural periods of1.8 seconds in horizontal direction and 1.4 seconds invertical direction, which almost met the design value. Andthe behavior of this system during the earthquake wassimulated by the seismic response analysis. Therefore, it isgreatly expected that the proposed system can be applied toactual nuclear power plants.

II. Outline of the Three-Dimensional Base IsolationSystem

1. Design ConceptAs shown in Fig.1, the proposed base isolation concept

is a three-dimensional air spring to support and isolate thesuperstructure by compressed air, which is composed of arubber sheet between the inner and outer cylinders,reinforcing polyester fabric, and wire cables. Herein, theinner cylinder is set on the bottom base-mat and the outercylinder is connected to the upper base-mat.

Fig.1 Cable reinforcing three-dimensional air spring concept

The distance between the inner and outer cylinders isthe allowable stroke for the device to move in the horizontaldirection, and the distance between the top of the innercylinder and the upper structure is the allowable stroke forthe device to move in the vertical direction. Since themovement in 3 dimensions is possible, three-dimensionalbase isolation is realized with a single device.

The shape of the inner cylinder connected to the rubbersheet is designed so that the total circumference of the innerand outer cylinders are the same to avoid wrinkles of therubber sheet at the inner cylinder when the rubber sheetscrolls down. This allows the smooth movement of thedevice, in both horizontal and vertical directions.

2. Outline of the Actual DeviceThe three-dimensional base isolation system applying to

an actual nuclear power plant was planned and designed.

The allowable horizontal half stroke and vertical half strokeof this air spring are respectively 1.0 meters and 0.5meters.The supporting design load is 52 MN, therefore a total of 32devices support the entire nuclear power plant buildingweight of 1,666MN. Under this condition the inner pressureis approximately 1.4MPa.

The target vertical frequency ‘fv’ was less than 1.0Hzand the vertical damping factor ‘hv’ was from 20% to 40%by Kato et al 1). The developed three-dimensional baseisolation system for an actual plant has the characteristics offh=0.27Hz, fv=0.35Hz, and h=20% in both horizontal andvertical directions for higher performance.

(1) Size and Layout of the Base Isolation DeviceThe layout of the devices for an nuclear power plant is

shown in Fig.2.

Fig.2 Three-dimensional basenuclear power plant

The overall specifications

follows; (a) Diameter of outer cylin (b) Diameter of inner cylin (c) Allowable horizontal d (d) Height of inner cylinde (e) Allowable vertical disp (f) Standard inner pressure (g) Main wire cable size, i (h) Secondary wire cable s (i) Thickness of rubber sh

(2) Supplementary EquipmenTogether with the main

equipment listed hereunder is u (a) Rocking prevention de (b) Horizontal damper, 20

(c) Vertical damper, 20% d (d) Air pressure controllin

- Air leak detector

0.5m

0.5m0.5m0.5m

3.0m

3.0m

3.0m3.0m

8.0m8.0m8.0m8.0m：：：：outer cylinderouter cylinderouter cylinderouter cylinder

6.0m6.0m6.0m6.0m：：：：inner cylinderinner cylinderinner cylinderinner cylinder

Horizontal dampersHorizontal dampersHorizontal dampersHorizontal dampers

Vertical dampVertical dampVertical dampVertical dampRocking preveRocking preveRocking preveRocking preve

53900

53900

53900

53900

Maintenan

88500885008850088500

ers +ers +ers +ers + Retaining wallRetaining wallRetaining wallRetaining wall

8008008008000000

isolation

of the

der: der: isplacemer: lacement:: nterval: ize, interv

eet: 3mm4mm

tair sprin

sed;vice% dampin

amping:

g system

ntion devntion devntion devntion dev

Air springAir springAir springAir spring

system layout at

air spring are as

8.0meters 6.0meters

nt: 1.0meter 3.0meters

0.5meters 1.4MPa

45mm,500mmal: 14mm,100mm at general portion at end portion

gs, supplementary

g:5MN oil damper80 units

5MN oil damper 22 units

iceiceiceice

3

- Air supply for small leaks - Air supply for the 32 air springs required for

initial air pressure

III. Test and Simulation Analysis1. Objectives

As the first step to confirm the capabilities of the three-dimensional base isolation system, pressure resistance testand function tests were carried out. The following itemswere studied through the tests to confirm the integrity of thethree-dimensional base isolation system. (a) Confirmation of pressure resistance and the

structural integrity of the wire cable reinforcingsystem.

(b) To confirm the smooth movement of the device in3-directions.

(c) To confirm the three-dimensional base isolationperformance of the function test specimenaccording to the theoretical evaluation.

2. Specimen for the Pressure Resistance Test A specimen with 0.3 meters in the outer diameter, whichis a scale model of 1/30 for the actual device, was designedand built to confirm the pressure resistance and the structuralintegrity (see Photo 1).

3. Results of the Pressure Resistance TestFrom the pressure resistance test using water, the air

tightness and structural integrity of the air spring composedof a rubber sheet, reinforcing textile and wire cables wereconfirmed. The rubber sheet is sealed by simple mechanismat the sides of the inner and outer cylinders.

The following results were obtained from the test; (a) Pressure resistance of the device up to 2.04MPa was

confirmed. (b) Leak occurred from the rubber seal at the inner and

outer cylinders. If sealed at a flat face with the use ofbolts were introduced, more pressure resistanceability would be expected.

(c) From the dismantled specimen, it was found that therubber sheet had a compression damage. So, therubber sheet should be designed to form a tensionstructure so that it does not directly contact the innerand outer cylinders.

4. Specimen for the Function TestConsidering the results of the pressure resistance test,

the function tests were conducted to confirm the three-dimensional movement of the device and its base isolatingperformance. The entire device is composed of 4 parts, theair spring, rocking prevention device, dampers and theweight, as shown in Fig.3. The scale of the air spring is 1/4of the actual size, where the outer diameter and the heightare 2 meters and 1.5 meters respectively. The inner pressurewithin the air spring is 0.25MPa and the gauge pressure is0.15MPa, supporting the weight of approximate 0.4MN.Table1 shows the similarity rule for testing. As shown in the

table, acceleration and stress values in the test specimen aresame with those in the actual device.

As the air spring itself does not have any restoring forcecharacteristics for the rocking, four sets of wire cablerocking prevention devices are combined, which surroundthe air spring in two horizontal directions.

Table 1 Similarity rule for the test specimen

Item DimensionSimilarity Rule(Test Specimen

/ Actual)n=4.0

Length L 1/n 0.25Velocity L/T 1/sqrt(n) 0.5

Acceleration L/T2 1 1.0Time T 1/sqrt(n) 0.5

Frequency 1/T sqrt(n) 2Mass M 1/n2 0.0625

InertiaForce M L/T2 1/n2 0.0625

Stress M /LT2 1 1Sectional

Area L2 1/n2 0.0625

Stiffness M/T2 1/n 0.25

Photo 1 Test specimen for pressure resistance test

Weight

SpecimenDamper

Shaking Table

2,0002,0002,0002,000

Cable Wire for Rocking Prevention

2 dimensions slider

Specimen

Fig.3 Test specimen for function test

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This prevention device consists of 4 pulleys, 2 wirecables and shafts to which the wire cables are attached. Theshafts are installed on the fixed apparatus through the sliderin the vertical direction. This device operates as follows(see Fig.4). Regarding the vertical displacement by thevertical motion, when two shafts move in the same directionthe two wire cables move smoothly without causing thetensile/compression force. If the air spring rocks androtates by the horizontal motion, one shaft moves down andother one moves up. Since the one side of crossing wirecables becomes under tension and the movement of the twoshafts is restricted by the tensile force of the wire cable, it ispossible to prevent from rocking. Herein, on the top of therocking prevention device connecting to the weight, slidersin two directions are set so that the smooth horizontalmovement is available.

Along with the rocking prevention device, fourdampers in the vertical direction and the four dampers in thehorizontal direction are set to reduce the displacementresponse, and weight is loaded above the spring.

5. Test Procedure of the Function TestThe function tests were conducted on a three-

dimensional shaking table (see Photo. 2).The contents of the function tests are as follows;

(1) Measuring the natural period of the device byevaluating the resonance curve obtained fromsinusoidal excitation in the horizontal and verticaldirections.

(2) Input of seismic waves (horizontal, vertical,horizontal and vertical combined) to confirm thesmooth movement of the device and the three-dimensional isolation performance, it’s seismicisolation performance and the effects ofsimultaneously input waves. The time axis of thewaves was reduced to half the actual one accordingto the similarity rule. The following waves wereused;

(a) FBR case study wave (horizontal: max 8.30m/s2) (b) FBR case study wave (vertical: max5.56m/s2) (c) FBR case study wave (horizontal and vertical)

6. Resonance curvesSinusoidal excitation test was conducted on the

function test specimen in two horizontal directions, X and Y,and the vertical direction Z. Fig.5 shows the resonancecurves and phase angles in each X, Y and Z directionsobtained from the tests, respectively. Here, the amplitudeshows the ratio of the acceleration at the top of the frame tothat of the shaking table at right above.

From the results, the natural period of the device in thehorizontal directions, X and Y, were found to be 1.79seconds, that was 0.56Hz, and the damping was evaluated16–17%. Herein, the secondary peeks in the X and Ydirections are due to the frame structure.

D

D

pulleys

wire cable

air spring（specimen）

shafts

Fig.4

Photo 2

B

(a) Device arrangement

movement of wirecable

Te

(b) Identical phase

resisting force ofwire cable

(c) Reverse phaseRocking prevention device

st specimen on 3D shaking table

As for the vertical, Z direction, a disagreement isrecognized between the frequencies at the primary peak ofthe resonance curve and at the phase angle of 90 degrees.This is thought to be due to the resonance with the shakingtable having natural period very close to 0.8Hz. Thereforethe resonance curve was modified by estimating the phaseangle with relative velocity at the point right above thedevice, Z1, and above the shaking table, Z2. As the result,the vertical natural period of 1.35 seconds, that was 0.74Hz,was estimated. In this way the natural period of the device inthe vertical direction was judged to be 1.35 seconds, thatwas 0.74Hz, and the damping was 26.54%.

confirmed. In Fig.8, the maximum acceleration value wasreduced to about 10m/s2 from about 40m/s2 in horizontaldirection. In the same way, in Fig.9, the maximumacceleration value was reduced to about 10m/s2 from about30m/s2 in vertical direction. Those phenomena show theefficiency of this three- dimensional base isolation device.The first and second natural frequency values of the testspecimen were observed in the base isolated responseacceleration spectrum in horizontal direction in Fig. 8. Thefirst natural frequency was also observed in verticaldirection in Fig.9.

Meanwhile there is little difference between the floorresponse spectrum of the horizontal wave in Fig. 8 and thecombination wave in Fig. 10. Furthermore, there is also littledifference between the floor response spectrum of thevertical wave in Fig.9 and the combination wave in Fig.11.From these phenomena, it can be judged that the influenceof the vertical movements on the horizontal response and thehorizontal movements on the vertical response can beignored. At the early stage of this development, there weresome concerns regarding the vibration characteristicinteraction between in horizontal and in vertical directions.However, by the results of this test it was clear that therewas little interaction between horizontal and vertical

0

1

2

3

4

5

0 1 2 3 4Hz

Amplitude

0.56Hz,h=16.0%

2.65Hz,h=5.1%

0

1

2

3

4

5

0 1 2 3 4 5

0.56Hz,h=16.9%

3.4Hz,h=8.3%

Amplitude

Hz

180

le

180

le

5

x-direction y-direction

z-direction(original) z-direction(modified)Fig.5 Resonance curves and phase angles

7. Floor Response SpectrumThe input motions of FBR case study waves at the

point right above the shaking table are shown in Fig.6 and 7.Comparisons between the floor response spectrum at

the point right above the device and horizontal, vertical andcombined waves are shown in Figs.8-11. Those spectra wereestimated setting the damping ratio to be 1.0%.

From those results, the seismic isolation performanceof the device in the horizontal and vertical directions can be

vibration characteristics.

Fig.6 FBR horizontal case study wave

Fig.7 FBR vertical case study wave

8. Fluctuation of Inner Air PressureThe fluctuation of inner air pressure in the test specimen

during the horizontal case study wave is shown in Fig.12.The fluctuation of measured inner air pressure is at mostabout 1.5%. Therefore it is thought that the fluctuation of airpressure is almost none.

The fluctuation of air pressure in the test specimenduring the FBR vertical case study wave and the combinedcase study wave are shown in Fig.13 and 14, respectively. Inthese cases, the fluctuations of measured inner air pressuresare 10% at most. Considering together with the floor

- 1 0- 1 0- 1 0- 1 0

- 5- 5- 5- 5

0000

5555

1 01 01 01 0

0000 1 01 01 01 0 2 02 02 02 0 3 03 03 03 0 4 04 04 04 0

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s22 22 )) ))

T i m e ( s )T i m e ( s )T i m e ( s )T i m e ( s )

- 8- 8- 8- 8

- 4- 4- 4- 4

0000

4444

8888

0000 1 01 01 01 0 2 02 02 02 0 3 03 03 03 0 4 04 04 04 0

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s22 22 )) ))

T i m e ( s )T i m e ( s )T i m e ( s )T i m e ( s )

-180

0

Phase Ang

-180

0

Phase Ang

0

180

0 1 2

Phase Angle

Hz

0

1

2

3

0 1 2Hz

Amplitude

0

180

0 1 2HzPh

ase Angle

0

1

2

3

4

5

0 1 2

absolute amplitude:(z1+z2)/z2relative amplitude:z1/z2

Amplitude

Hz

response spectrum mentioned above, the influence of thevertical movement on the horizontal response is thought tobe very small.

The comparison of natural periods between the testresults and the design values are shown in Table 2.

The design natural period of the device in horizontalection is evaluated from the gauge pressure and size of air spring, and effect of the inclination of the wire cabledded. Each cable wire is fixed on its both ends to the topthe inner and outer cylinders. Since the cable wire is settically in the ditch of the outer cylinder, the wire makelination with the end at inner cylinder. This inclinationkes the restoring force.The design natural period of the device in vertical

ection is evaluated from the inner pressure, inner andter cylinder size, and the volume of the air spring.rthermore, the volume of the air spring is estimated byuming adiabatic change. (Tokita et al, 19922))

From the table, it is confirmed that the function testults to be almost the same as the design value from theoretical evaluation.

Table 2 Comparison of natural periods

dirtheis aof verincma

dirouFuass

resthe

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Acceleration(m/s

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s22 22 )) ))

Period(s)Period(s)Period(s)Period(s)

0.1 1 5(Actual

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Acceleration(m/s

Acceleration(m/s

Acceleration(m/s22 22 )) ))

Period(s)Period(s)Period(s)Period(s)

0.1 1 5(Actual

Fig. 8 Horizontal floorresponse spectrum ofx-direction input wave

Fig. 9 Vertical floorresponse spectrum of

z-direction input wave

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Acceleration(m/s22 22 )) ))

Period(s)Period(s)Period(s)Period(s)

0.1 1 5(Actua

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Acceleration(m/s

Acceleration(m/s

Acceleration(m/s

Acceleration(m/s22 22 )) ))

Period(s)Period(s)Period(s)Period(s)

0.1 1 5(Actual tim

Fig. 10 Horizontal floorresponse spectrum of

Fig. 11 Vertical floorresponse spectrum of

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9. Comparison of Test Results With the Design Values

10

rechFiisdecoswchco

diducoteofpeho

spisanflofirpr

xz-direction input wave xz-direction input wave

-0.004

-0.002

0

0.002

0.004

0 5 10 15 20 25 30 35 40

Pressure range (MPa)

Time（ s）

0.157

Fig.12 Inner air pressure fluctuation (x direction)

-0.02

-0.01

0

0.01

0.02

0 5 10 15 20 25 30 35 40

Pressure range (MPa)

Time (s)

0.157

Fig. 13 Inner air pressure fluctuation (z direction)

-0.02

-0.01

0

0.01

0.02

0 5 10 15 20 25 30 35 40

Pressure range (MPa)

T ime (s)

0.157

Fig. 14 Inner air pressure fluctuation (xz direction)

Design naturalPeriod

(in detail)

Naturalperiod by

test

Design/ Test

Horizontaldirection(first order)

1.83(sec) 1.79(sec) 1.04

Verticaldirection 1.38(sec) 1.35(sec) 1.04

. Simulation AnalysisSimulation analyses were carried out by the seismic

sponse analyses. The analysis model and the details of thearacteristics used in the simulation analyses are shown ingure 15. The analysis model is consisted of a baseolation device and a frame structure. The base isolationvice is consisted of sway, vertical and rocking spring andrresponding dampers. The frame structure is consisted ofay, vertical and rocking springs, and the dampingaracteristics are considered by material dampingefficients.

As for the horizontal and vertical responsesplacements of the three-dimensional isolation devicering the FBR case study waves, Fig.16 shows themparison of the time histories between the analyses andst results. The analyses simulate the response displacement the test results very well. The first and second naturalriods of the superstructure are simulated properly inrizontal direction.

Regarding the horizontal and vertical floor responseectrum at the point just above the three-dimensionalolation device, Fig.17 shows the comparison between thealyses and the test results. The analyses also simulate theor response accelerations of the test results very well. Thest natural period of the superstructure is also simulatedoperly in vertical direction.

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It was confirmed that the responses of this three-dimensional air spring to earthquake motions could besimulated with high accuracy by the method of seismicresponse analysis.

IV. Conclusion In order to establish the site-free design and to reducethe construction cost of the commercialized FBR, the three-dimensional base isolation system has been developed since2000. The superlative three-dimensional cable reinforced baseisolation system to support an entire nuclear power plantbuilding was developed, which is composed of air springs,rocking prevention devices and dampers that are effective inboth horizontal and vertical directions. The system hasnatural frequencies about 4seconds in horizontal and 3seconds in vertical directions. The device supports about52MN and its inner air pressure is about 1.4MPa.

From the results of the enforced pressure resistance testand function tests, the pressure resistance performance ofapproximately 2MPa and the seismic isolation functions in 3directions were confirmed. The performance of thedeveloped system can be evaluated by the theoreticalmethod and can be simulated the actual behavior by theseismic response analysis.

Accordingly, it is concluded that the developed systemis feasible for applying to actual nuclear power plants.

(b) Floor response spectrum in vertical direction

Fig.17 Comparison of the floor response spectrumbetween analyses and test results at the pointjust above the three-dimensional isolationdevice

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1F-Analysis1F-Analysis1F-Analysis1F-Analysis1F-Test1F-Test1F-Test1F-TestInput MotionInput MotionInput MotionInput Motion

Acceleration (m/s

Acceleration (m/s

Acceleration (m/s

Acceleration (m/s22 22 )) ))

Period (s)Period (s)Period (s)Period (s)

-200-200-200-200

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200200200200

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AnalysisAnalysisAnalysisAnalysisTestTestTestTest

Hori. Displacemnet

Hori. Displacemnet

Hori. Displacemnet

Hori. Displacemnet

(mm)

(mm)

(mm)(mm)

Time (s)Time (s)Time (s)Time (s)(a) Horizontal displacement response

-100-100-100-100

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Vert. Displacemnet

Vert. Displacemnet

Vert. Displacemnet

Vert. Displacemnet

(mm)

(mm)

(mm)(mm)

Time (s)Time (s)Time (s)Time (s)(b) Vertical displacement response

Fig.16 Comparison of the displacement responsetime-history between analyses and test resultsfor the three-dimensional isolation

：Axial spring ：Shear spring ：Rotational ：Damper spring

▽5.075m

▽4.275m

▽3.475m

▽2.675m

▽1.750m

ＷＷＷＷRRRR、Ｊ、Ｊ、Ｊ、ＪRRRR

ＷＷＷＷ4444、Ｊ、Ｊ、Ｊ、Ｊ4444

ＷＷＷＷ3333、Ｊ、Ｊ、Ｊ、Ｊ3333

ＷＷＷＷ2222、Ｊ、Ｊ、Ｊ、Ｊ2222

ＷＷＷＷ1111、Ｊ、Ｊ、Ｊ、Ｊ1111

FKvFKvFKvFKv FKh FKh FKh FKh FKrFKrFKrFKr

FKvFKvFKvFKv FKh FKh FKh FKh FKrFKrFKrFKr

FKvFKvFKvFKv FKh FKh FKh FKh FKrFKrFKrFKr

FKvFKvFKvFKv FKh FKh FKh FKh FKrFKrFKrFKr

MChMChMChMCh

MKvMKvMKvMKv MKh MKh MKh MKh MKrMKrMKrMKr

MCv2 MCv1MCv2 MCv1MCv2 MCv1MCv2 MCv1

ＷＷＷＷRRRR：：：： 31.12 31.12 31.12 31.12 kNkNkNkNＷＷＷＷ4444～Ｗ～Ｗ～Ｗ～Ｗ2222：：：：15.96 15.96 15.96 15.96 kNkNkNkNＷＷＷＷ1111：：：： 313.24 313.24 313.24 313.24 kNkNkNkNＪＪＪＪRRRR：：：： 3,315 N 3,315 N 3,315 N 3,315 N････mmmm2222

ＪＪＪＪ4444～Ｊ～Ｊ～Ｊ～Ｊ2222：：：：1,580 N1,580 N1,580 N1,580 N････mmmm2222

ＪＪＪＪ1111：：：： 558,989 N 558,989 N 558,989 N 558,989 N････mmmm2222

FKhFKhFKhFKh：：：：4.00 MN/m4.00 MN/m4.00 MN/m4.00 MN/mFKvFKvFKvFKv：：：：3,340 MN/m3,340 MN/m3,340 MN/m3,340 MN/mFKrFKrFKrFKr：：：：1.891.891.891.89××××101010109999 N N N N････m/m/m/m/radradradrad

MKvMKvMKvMKv：：：：0.86 MN/m0.86 MN/m0.86 MN/m0.86 MN/mMKhMKhMKhMKh：：：：0.49 MN/m0.49 MN/m0.49 MN/m0.49 MN/mMKrMKrMKrMKr：：：：2.702.702.702.70××××101010107777 N N N N････m/m/m/m/radradradrad

MChMChMChMCh：：：：44.8 44.8 44.8 44.8 kN/(m/s)kN/(m/s)kN/(m/s)kN/(m/s)MCv1MCv1MCv1MCv1、、、、MCv2MCv2MCv2MCv2：：：：34.3 34.3 34.3 34.3 kN /(m/s)kN /(m/s)kN /(m/s)kN /(m/s)

Fig.15 Analysis model

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0.010.010.010.01 0.10.10.10.1 1111 10101010

1F-Analysis1F-Analysis1F-Analysis1F-Analysis1F-Test1F-Test1F-Test1F-TestInput MotionInput MotionInput MotionInput Motion

Acceleration (m/s

Acceleration (m/s

Acceleration (m/s

Acceleration (m/s22 22 )) ))

Period (s)Period (s)Period (s)Period (s)

(a) Floor response spectrum in horizontal direction

8

AcknowledgmentThis study was performed under the sponsorship of the

Ministry of Trade and Industry of Japan. Specialappreciation is given to Mr. Wataru Ota of The YokohamaRubber Co., Ltd, Mr. Hideki Tagawa of Shinko Wire Co.,Ltd, and Mr. Akimoto Uchikawa of Teijin Limited for theirinvaluable technical support to this study.

References1) Kato, A., Umeki, K., Morishita, M., Fujita, T.,

Midorikawa, S. ”A large Scale Ongoing R&D Projecton Three-Dimensional Seismic Isolation for FBR inJapan”, ASME PVP, Aug, 2002

2) Tokita, Y. and Morimura, M. ”Vibration controlhandbook”, Fuji Techonosystem, Tokyo, Japan,pp.413-420, 1992