Performance of Base Isolated Structure for Tsunami Loading Mineo Takayama Fukuoka University
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Performance of Base Isolated Structure for Tsunami Loading
Mineo TakayamaFukuoka University
Topics
• Performance of Seismically Isolated Buildings based on Earthquake Records
• Guideline for Structural Design of Tsunami Evacuation Buildings
• Response of Seismically Isolated building due to Tsunami Wave Force
2005 Fukuoka
1995 Kobe
2004 NiigataFukushima NPP
Tokyo
2011 Tohoku
2000 Tottori
2008 Iwate-Miyagi
2007 Niigata Chuetsu
2003 Tokachi-oki
Major earthquakes in the last 20 years
20??
Seismically Isolated Building at Fukushima Dai-ichi & Dai-ni NPP
0
1
2
3
0 200 400 600 800
Fukushima Dai-ichi
NS-dir.EW-dir.
Stor
y
Max. Acceleration (gal)
0
1
2
3
0 200 400 600 800
Fukushima Dai-ni
NS-dir.EW-dir.
Stor
y
Max. Acceleration (gal)
1/4
1/2
0.0
0.5
1.0
1.5
2.0
2.5
0 200 400 600 800
1995 Kobe2004 Niigata2005 Fukuoka2011 Tohoku (1FL/BASE)2011 Tohoku (ROOF/BASE)
Am
plif
icat
ion
of A
ccel
erat
ion
Max. Acceleration at BASE (gal)
Amplification Factor of Acceleration of Seismically Isolated Buildings
Good performance
Total Damage$2.2 Trillion
Total Damage$2.2 Trillion
Number of Death
320,000
Number of Death
320,000
Height of Tsunami WaveFrom 15m to 34m
Damage Estimation of Nankai Trough EarthquakeDamage Estimation of Nankai Trough Earthquake
gah
h
ah
Inundation Depth
Tsunami Wave Pressure
Building
Hydrostatic Force Distribution due to Tsunami Wave
z
Water Depth Coefficient
Japanese Guidelines for Tsunami Evacuation Building
zahgqZ
Zq
: Tsunami pressure: The mass of unit volume of water (1.0 t/m3) : Gravitational acceleration (9.8 m/s2): Design Inundation depth (m): The height of the part of interest from the
ground level, (m): Water depth coefficient
ahz 0
ghz
Tsunami Pressure
a
Water Depth Coefficient “a”
2
1
Z
ZZ dzBzahgQ
Qz: Tsunami force in direction of travel for structural design (kN)
B: Width of pressure-receiving surface of relevant part (m)
Z1: Minimum height of pressure-receiving surface (0≤Z1≤Z2) (m)
Z2: Maximum height of pressure-receiving surface (Z1≤Z2≤ah) (m)
Tsunami Force
gah
H
DB
Isolation Layer
Superstructure
Base
H
D
hah
Inundation Depth
Isolation Layer
Tsunami Loading
Seismically Isolated Building Modelfor Tsunami Response
No. of stories N
HeightH (m)
Depth D (m)
H/D =1 H/D =3 H/D =5
5 15 15 5 310 30 30 10 615 45 45 15 920 60 60 20 1230 90 90 30 18
Building Model Dimensions
DBNwW 1Total Weight of Building Models
(w=12 kN/m2)
Hysteresis Characteristics ofIsolation Layer
SQfK
tQ
t
Shear Force
Shear Deformation0
gKWT
ff 2
WQS
S
Stf
t
gTWQ
2
24
Yield Shear Coefficient
Isolation Period
gah
H
D
hah
Inundation Depth
Tsunami Load Acting on Isolation Layer
gBahQt 2
21
tQ
These influences were not included:Openings such as windowsBuoyancyFloating debris
DNw
gahWQt
t 12
2
0
10
20
30
40
50
0 0.2 0.4 0.6 0.8 1Hei
ght o
f Tsu
nam
i Pre
ssur
e a
h (m
)
Base Shear Coefficient t
H=90m H=60mH=45m
H=30m
H=15m
H/D=10
10
20
30
40
50
0 0.2 0.4 0.6 0.8 1Base Shear Coefficient t
H=90m
H=60m
H=45m
H=30m
H=15m
H/D=3
0
10
20
30
40
50
0 0.2 0.4 0.6 0.8 1
H=90m
H=60m
H=45m
H=30m
H=15m
H/D=5
Base Shear Coefficient t
Height of Tsunami Pressure “ah”vs. Base Shear Coefficient
H/D=1 H/D=3 H/D=5
t
ah
Stf
t
gT
2
2
4
Prediction of Max. Deformation
0
10
20
30
40
0 0.2 0.4 0.6 0.8 1
H/D=3, s=0.03
Hei
ght o
f Tsu
nam
i Pre
ssur
e a
h (m
)
Max. Deformation (m)
Solid Line:Tf=3sDashed Line:Tf=5s
H=90m
H=60m
H=45m
H=30m
H=15m
H/D=3
03.0Ssec5or sec3fT
ah
t
0
0.1
0.2
0.3
0.4
0.5
0 0.2 0.4 0.6 0.8 1
H/D=3N
orm
aliz
ed T
suna
mi H
eigh
t ah
/H
Max. Deformation (m)
Tf=3s
Tf=5s
s=0.03
Normalized Height of Tsunami Pressurevs. Max. Deformation
H=15m--90mHah
t
Tf a H/D =1 H/D =3 H/D =5
3sec3 0.14H 0.08H 0.06H
1.5 0.28H 0.16H 0.13H
5sec3 0.10H 0.05H 0.04H
1.5 0.20H 0.10H 0.08H
Tsunami Inundation Depth when Max. Deformation of Isolation Layer
Reaches 40 cmS = 0.03
2km
Isolated Warehousehit by the Tsunami, 2011 Tohoku Eq.
Sendai-Shiogama PortMiyagi Prefecture
200m
Structural System of Warehouse
Superstructure :Steel structure
Isolation System :24 HDRs
Diameter：800mm or 850mm
Isolation Period :
Yield Shear Coefficient:sec2.4fT
50m30
m
30m
03.0S
Floor Plan
Section
W=93240kN
Inundation Depth : 4m
4m
0
2
4
6
8
10
0 0.2 0.4 0.6 0.8 1
B=30mB=50mB=58.3m
Inum
datio
n D
epth
h (m
)
Max. Deformation (m)
a=2.0
0
2
4
6
8
10
0 0.2 0.4 0.6 0.8 1
B=30mB=50mB=58.3m
Inum
datio
n D
epth
h (m
)
Max. Deformation (m)
a=1.5
Calculation of Max. Deformation
Observed Max. Deformation : 21 cm
30m
50m
Direction of TsunamiTsunami Height : 4 m
a=1.5 a=2.0
0.2a5.1am500
ShelterOcean
The Moving Directionof Tsunami
m200 m2000 Can the hydrostatic tsunami pressure become
applicable to seismically isolated buildings?Can the hydrostatic tsunami pressure become applicable to seismically isolated buildings?
Selection of Water Depth Coefficient
Further research into matters such as the validity of the method used to set the tsunami load and the influence of buoyancy is required to confirm the tsunami safety of seismically isolated buildings.
Further research into matters such as the validity of the method used to set the tsunami load and the influence of buoyancy is required to confirm the tsunami safety of seismically isolated buildings.
It was confirmed that most seismically isolated buildings demonstrated an adequate seismic isolation effect in response to the earthquake.
In this research, we applied the same tsunami loads as those used in the design of tsunami evacuation buildings. As tsunami inundation depth increases, large shear forces and deformation occur in the isolation layer.
The smaller the size of the building (height and depth) and the more flexible the isolation layer, the greater the deformation of the isolation layer.
Conclusions
“Disaster will attack when you have forgotten”
Thank you for your attention
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