Base Isolation Technology

November, 2000

・ Principle of Base Isolation System

・ Example of Base-isolation Building

・ Analytical Model of Base-isolation Building

・ Input Earthquake Waves

・ Results of Earthquake Response Analyses

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Principle of Base Isolation System

Base Isolation System is like a Suspension System of Motorcar

Soft spring + Oil Damper

Damper Laminated rubber bearing

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Laminated rubber bearing

Soft in Horizontal directionHard in Vertical direction

Rubber Sheet

Steel Plate

Base Isolation System

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Base Isolation System

Laminated rubber bearing

Rubber block

Rubber block

Laminated rubber bearing

1. Vertical direction

2. Horizontal direction

Principle of Laminated rubber bearing

Rubber block

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Steel damper

Lead damper

Base Isolation System Damper

Oil damper

Friction damper with Coned disc springs

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Example of Base-isolation Building

Base Isolated Research Building Base Isolation Device

Location : Tokyo

Architect : Obayashi Corporation

Structure : RC ; B1,5F

Total floor area : 1,624 ｍ 2

Date of completion : August 1986

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Example of Base-isolation Building

Base Isolated Research Building (Elevation)

Base Isolation Device (Floor Plan)

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Rubber BearingSteel Damper

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Base Isolation Building

Principle

Seismic Acceleration Response Spectrum

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Comparison of Seismic Response

Am

pli f

icat

ion

fact

or o

f ac

c ele

r atio

n

Period(sec.)

Conventional Building

Base Isolation Building

Story Displacement Acceleration Story Displacement Acceleration

El Centro 1940NS25Kine Input

Base Isolation System

OBAYASHI99

Analytical Model of Base-isolation Building

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Story Weight Total Horizontal Natural NaturalWeight stiffness Frequency period

Floor W ton W ton KH ton/cm Hz sec6F 543 543

415 1 mode 0.754 1.3265

5F 412 955415 2 mode 2.598 0.3849

4F 412 1,367455 3 mode 4.948 0.2021

3F 422 1,789518 4 mode 7.189 0.1391

2F 414 2,203615 5 mode 8.985 0.1113

1F 705 2,90881.36 6 mode 10.341 0.0967

Mode

EigenvalueAnalytical Model

4.2m

4.2m

4.25m

4.3m

4.3m

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0.5mRubber Bearing Steel Damper

5

4

3

2

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Analytical Model of Base-isolation Building

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Hysteresis Characteristics

0

100

200

300

400

500

600

0.0 1.0 2.0 3.0 4.0 5.0

Displasement(cm)

1F(Base-isolation)6F

5F

4F

3F

2F

OBAYASHI

Input Earthquake Waves

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KOBENS(818gal)

DZCEW(369gal)

YPTNS(321gal)

-1000

-500

0

500

1000

0 5 10 15 20 25

Inpu

t Acc

.(ga

l)

Time (sec.)

-400-300-200-100

0100200300400

0 5 10 15 20 25

Inpu

t Acc

.(ga

l)

Time (sec.)

-400-300-200-100

0100200300400

0 20 40 60 80 100

Inpu

t Acc

.(ga

l)

Time (sec.)

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Effectiveness of Base Isolation System

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DZCEW369gal YPTNS321gal

0

1

2

3

4

5

6

0 200 400 600 800 1000

Acceleration Distribution (DZCEW)

ConventionalBase-isolation

story

gal0

1

2

3

4

5

6

0 200 400 600 800 1000

Acceleration Distribution (YPTNS)

ConventionalBase-isolation

story

gal

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Results of Earthquake Response Analyses

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Response Acceleration Story Displacement

0

1

2

3

4

5

6

0 5 10 15 20 25

KOBENS 818galDZCEW 369galYPTNS 321gal

story

cm 0

1

2

3

4

5

6

0 5 10 15 20 25

KOBENS 818galDZCEW 369galYPTNS 321gal

story

cm

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-1000

-500

0

500

1000

0 5 10 15 20 25Time (sec.)

KOBENS(818gal)

DZCEW(369gal)

YPTNS(321gal)

Results of Earthquake Response Analyses

-1000

-500

0

500

1000

0 5 10 15 20 25

KOBENS Base-isolation

Acc.(gal)

(sec.)

-400-300-200-100

0100200300400

0 5 10 15 20 25

DZCEW Base-isolation

Acc.(gal)

(sec.)

-400-300-200-100

0100200300400

0 10 20 30 40 50 60

YPTNS Base-isolation

Acc.(gal)

(sec.)

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Results of Earthquake Response Analyses

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Hysteresis Characteristics

0

100

200

300

400

500

600

0.0 1.0 2.0 3.0 4.0 5.0

Displasement(cm)

1F(Base-isolation)6F

5F

4F

3F

2F

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Results of Earthquake Response Analyses

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-600

-400

-200

0

200

400

600

-30 -20 -10 0 10 20 30

1F2F3F4F5F6F

Shere Force (ton)

Displasement (cm)

-600

-400

-200

0

200

400

600

-30 -20 -10 0 10 20 30

1F2F3F4F5F6F

Shere Force (ton)

Displasement (cm)

DZCEW YPTNS

Hysteresis Characteristics

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Effects of Base Isolation System

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Building with Seismic Isolation

Conventional Building

・ Improvement for Safety of Building・ Keep for Function of Building・ Preservation for Property

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Application of Base-isolated Structure

１） Government and Municipal Office, Fire Station, Police Station, Broadcasting Station２） Hospital, Social welfare facilities３） Laboratory４） Computer Center５） Museum, Gallery, Library６） Apartment House７） Cultural Asset, Historic Structure

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