Taiki SAITO Building Research Institute, JAPAN ( tsaito@kenken.go.jp ) Seismic Performance of Base Isolation Buildings during 2003 Off Tokachi Earthquake Taiki SAITO Building Research Institute, JAPAN ( tsaito@kenken.go.jp ) 1

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

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

JMA Intensity Map 4 (Data: JMA)

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

Damage of roads 6 (Photos from Hokkaido Journal)

Damage of buildings 7 (Photos from Hokkaido Journal)

Damage of buildings 8 (Photos from Hokkaido Journal)

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)

Effect of long period earthquake Tomakomai Contour Map for Response Velocity (T=7 sec) 7 sec Earthquake Velocity Wave (0.05-0.5Hz) 10 (Data: Disaster Prevention Research Center)

Base isolation buildings in Kushiro city 11

[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. 36-38, N0.43, 2004.2 12

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

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

Distribution of max. acceleration response 15

Orbit of displacement 16

[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. 31-35, N0.43, 2004.2 17

Allocation of base isolation devices 1 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

Base isolation devices Lead rubber bearing 19

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

Orbit of displacement X(EW) Ｙ(NS) 21

[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. 41-43, N0.43, 2004.2 22

Allocation of base isolation devices 50 High damping rubber bearings 23

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

Distribution of max. acceleration response RF 3F 2F 1F BF 25

Orbit of displacement N EW NS NS UD EW 26

[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. 39-40, N0.43, 2004.2 27

Allocation of base isolation devices 15 Natural rubber bearings, 11 lead dampers, and 6 steel dampers 28

Base isolation devices natural rubber bearing steel damper lead damper 29

Characteristics of base isolation devices 30

Acceleration response (X-direction) 31

Acceleration response (Y-direction) 32

Orbit of displacement 33

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 　　 　1 2 3 4 (1995 Kobe earthquake) 34

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