1. Taiki SAITO Building Research Institute, JAPAN ( tsaito@kenken.go.jp )
Seismic Performance of Base Isolation Buildings during Off Tokachi Earthquake
Taiki SAITO
Building Research Institute, JAPAN
( ) 1

2. Outline 2 2003 Off Tokachi Earthquake
Characteristics of earthquake
Damage photos
Earthquake response of base isolation buildings
Government building
Office building
Hospital
Bank
Summary 2

3. 2003 Off Tokachi Earthquake
Date: 26th September, 2003
Time: 4:50 am
Magnitude: 8.0
Location: 41°46.78'N 144°4.71'E
Depth: 42km
Missing: 2 people
Injured: 847 people 3

4. JMA Intensity Map 4
(Data: JMA)

5. Damage by Tsunami after the earthquake5
(Photos from Hokkaido Journal)

6. Damage of roads 6
(Photos from Hokkaido Journal)

7. Damage of buildings 7
(Photos from Hokkaido Journal)

8. Damage of buildings 8
(Photos from Hokkaido Journal)

9. Damage of Oil Tank 9 Natural Period for Sloshing = 7 sec
Tomakomai City
(220 km from Epicenter)
Natural Period for Sloshing
= 7 sec 9
(Photos from Hokkaido Journal)

10. Effect of long period earthquake
Tomakomai
Contour Map for Response Velocity (T=7 sec)
7 sec
Earthquake Velocity Wave ( Hz) 10
(Data: Disaster Prevention Research Center)

11. Base isolation buildings in Kushiro city11

12. [1] Government office building
SRC structure with steel braces
9-story building with 1-story basement
Reference:
T.Kajima, A.Ito, H. Fujita,
“Earthquake record of 2003 Off Kushiro Earthquake at Kushiro-government office”, Mensin Journal, pp , N0.43, 12

13. Allocation of base isolation devices
Sensor
64 Natural rubber bearings, 56 lead dampers and 32 steel dampers 13

14. Observed records
Place
Maximum Acc,(cm/s2)
N167°E
N257°E UD
Building
09F
93.8
120.6
183.6
01F
70.3
80.6
85.1
B1F
154.1
192.4
76.4
Ground GL
210.2
259.8
106.3
G10
173.3
214.4
71.9
G34
137.6
134.5
61.5 14

15. Distribution of max. acceleration response15

16. Orbit of displacement 16

17. [2] Office building 17 RC wall structure 3-story building Reference:
Y.Takenaka, T.Yasuda, Y. Suzuki,
“Earthquake observation of base isolation building in Kushiro city at 2003 Off Kushiro Earthquake”, Mensin Journal, pp , N0.43, 17

18. Allocation of base isolation devices1 A 2 B X Y
Base Isolator
: 600 φ ▽
装置芯
Basement Sensor
1FL Sensor
RFL Sensor
Scratch Board
4 Lead rubber bearings 18

19. Base isolation devices
Lead rubber bearing 19

20. Distribution of max. acceleration response
Ｘ(EW)
Ｙ(NS) UD
RFL
228
141 －
1FL
229
129
Basement
Input
286
274
114 20

21. Orbit of displacement
X(EW)
Ｙ(NS) 21

22. [3] Hospital building 22 RC structure 3-story building with penthouse
Fist base isolation hospital in Japan
Reference:
S.Sakai, Y.Ito, T.Iida,
“Earthquake respnse of base isolation hospital”, Mensin Journal, pp , N0.43, 22

23. Allocation of base isolation devices
50 High damping rubber bearings 23

24. Observed records 24 MAX= 155 cm/s2 (EW) MAX= 212 cm/s2 (EW)
MAX= 123 cm/s2 (NS)
MAX= 142 cm/s2 (NS)
MAX= 145 cm/s2 (UD)
MAX= 100 cm/s2 (UD) 24

25. Distribution of max. acceleration responseRF 3F 2F 1F BF 25

26. Orbit of displacement N EW NS NS UD EW 26

27. [1] Banking facility 27 SRC structure
７-story building with 1-story basement and penthouse
Reference:
M.Todo, H.Seki,
“Earthquake record of 2003 Off Kushiro Earthquake at Kushiro-bank headquarter”, Mensin Journal, pp , N0.43, 27

28. Allocation of base isolation devices
15 Natural rubber bearings, lead dampers, and steel dampers 28

29. Base isolation devices
natural rubber bearing
steel damper
lead damper 29

30. Characteristics of base isolation devices30

31. Acceleration response (X-direction)31

32. Acceleration response (Y-direction)32

33. Orbit of displacement 33

34. Summary of base isolation effect
0.95
0.80
0.73
0.73
0.54
0.82
0.47
0.87
0.35
0.42
0.45
0.22
　　 　 (1995 Kobe earthquake) 34

35. Summary of displacement
Building 1
Building 2 N
Building 3
Building 4 35