Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanRESPONSES OF CONTROLLED TALL BUILDINGSIN TOKYO SUBJECTED TO
THE GREAT EAST JAPAN EARTHQUAKE
Kazuhiko KASAI1, Wenchuan PU2 and Akira WADA3
1

Professor, Structural Engineering Research Center, Tokyo Institute of Technology,
Yokohama, Japan, kasai@serc.titech.ac.jp
2
Associate Professor, Department of Civil Engineering, Wuhan University of Technology,
Wuhan, China, puwuchuan@gmail.com
3
President, Architectural Institue of Japan, Tokyo, Japan,
wada@akira-wada.com

ABSTRACT: Many tall buildings in Tokyo metropolitan area were strongly shaken
during the Great East Japan Earthquake, March 11, 2011. Most of them are less than 40
years old, and have not experienced the shaking of such a strong level. The tallbuildings less than 15 years old, constructed after the 1995 Kobe Earthquake, aretypically response-controlled by using dampers, due to the increased concern about
serious consequence of seismic damage in major buildings. Some of such buildings are
instrumented with sensors and their motions were recorded during the event. This
paper discusses the responses of the Japanese controlled tall buildings based on theirmotions recorded in Tokyo during the 2011 Great East Japan Earthquake. The
responses are also compared with those of conventional seismic-resistant buildings.
Key Words: Great East Japan earthquake, tall buildings, response-controlled buildings,
vibration period, damping ratio

INTRODUCTION
The Great East Japan Earthquake
At 14:46 on March 11, 2011, the East Japan Earthquake of magnitude 9.0 occurred off Sanriku coastof Japan. It caused tremendous tsunami hazard in the pacific coast of eastern Japan, killing more than
15,000 people, destroying and washing away cities.
The epicenter was 129km from Sendai, the largest city in the northeast of Japan. The depth of the
hypocenter was 24 km. The recorded magnitude places the earthquake as the fourth largest in theworld since 1900, following 1960 Chile Earthquake M9.5, 1964 Alaska Earthquake M9.2, 2004
Sumatra Earthquake M9.2, and it is the largest in Japan since modern instrumental recording began
130 years ago. The earthquake has recorded the seismic intensity 7, highest in the Japan
Meteorological Agency scale, in the north of Miyagi prefecture.
There were many strong earthquake observation networks in operation under the management of1099

research institutes, universities and companies. A large amount of data was well recorded during theearthquake, and various maps are available. For instance, the readers may refer to the distribution ofpeak ground acceleration (PGA) recorded during the earthquake, summarized by Earthquake ResearchInstitute (ERI), the University of Tokyo.
K-NET Tsukidate, located in Kurihara city, Miyagi prefecture, is the only station that recorded
Intensity 7 during the main shock. A maximum acceleration in the N-S direction reached almost 2699
cm/s2, representing that the main shock caused excessively severe earthquake motions. Strong motions
with PGA larger than 200 cm/s2 were observed over a very wide area from Ibaraki to South Iwate.
Tokyo is located 300 km away from the epicenter, and its stations recorded PGA of 50 to 150 cm/s2.
The records from stations close to epicenter, such as Sendai, show two wave groups with a timeinterval of about 50 seconds, and those from southern station such as Ibaraki and Tokyo areas show
one large wave group. Such phenomenon occurred due to difference of focal rupture process and thewave propagation to recording stations in the northern and southern portions of the fault area of 500
km long.
Building responses and records
Where ground acceleration was large, except for some areas of soft ground, the response spectrum
indicates short dominant period, which was probably the main reason for relatively small seismic
damage.
On the other hand, Tokyo relatively far from the epicenter was subjected to theground motion ofshort to long period components. Many tall buildings have been constructed for the last 40 years inTokyo, and the shaking they experienced is much stronger than those in the past. Therefore, theresponse observed are believed to be the precursors for the performance of the tall buildings against
the stronger shaking that will definitely occur in future.
Since some tall buildings were instrumented with accelerometers, acceleration records obtained
during the earthquake would be one of the best resources to study the building responses (Kasai
2011a).
Objectives and scopes
Pursuant to these, the objective of the present paper is to clarify behavior of tall buildings in Tokyo,
based on the responses recorded during the 2011 Great East Japan Earthquake. The paper will analyze
acceleration records of a typical seismically-resistant building with a low damping ratio, andresponse-controlled buildings whose damping ratios are increased by the new technology using
various types of dampers.
Virtually, most Japanese tall buildings constructed after the 1995 Great Hanshin Earthquake areresponse-controlled in order to protect not only the human lives but also the structural components,
nonstructural components, and building functions. Therefore, effectiveness of the new technology inachieving the above-mentioned performance will be discussed.

OVERVIEW OF BUILDINGS EXAMINED
Nine tall buildings selected
We select one conventional seismically-resistant building and eight response-controlled buildings thathave various types of dampers for seismic energy dissipation. All the selected buildings are over 60
meters high, commonly considered as the lower limit of height of high-rise buildings in Japan. Timehistory analysis is compulsory for these buildings when performing structural design. The number offloors of the buildings ranges from 19 to 54. Note that some of the buildings will be anonymous in thispaper, due to the request of building owners.
In Table 1, structural types of buildings, fundamental periods of x- and y-directions, peak

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accelerations of top and base are given. Hereinafter, the top means the highest instrumented floor, andthe base means the instrumented floor closest to the ground level. The vibration periods are obtained
from the transfer function of acceleration of top to base; the frequency at the peak value of transfer
function is defined as the vibration period of structure.
The peak acceleration at the base ranged from 52 to 142 cm/s2, and their average is about 80 cm/s2.
The peak acceleration response at top of the building ranged from 113 to 251 cm/s2, and the averagestory drift angle (ratio of peak displacement of top to its height) is 1/300 rad. at most.
Table 1. Basic information on buildings examined.
No. Type of Damper
1
2
3
4
5
6
7
8
9

No Damper
Steel+Viscous
Viscous
Steel+Viscous
Viscous
Oil
Oil
Steel+Viscous
Oil

Type of Number Height
Frame of Floors (m)
S
29
127.8
S
14
66.0
S
19
79.5
S
21
99.6
CFT+S
37
178.0
CFT+S
41
186.9
CFT+S
42
157.3
CFT+S
43
152.5
S
54
223.0

Period (s)XY
2.96 3.09
1.21 1.66
1.83 1.58
1.83 1.97
4.96 5.21
3.97 4.10
4.78 4.31
4.75 4.23
5.37 6.43

Top Acc. (cm/s2) Base Acc. (cm/s2)
X
Y
X
Y
235
316
91
89
217
155
112
127
142
154
75
71
113
128
75
71
99
145
108
92
118
124
53
52
147
152
47
68
136
199
72
78
236
161
94
142

Amplif. Factor
X
Y
2.58
3.55
1.94
1.22
1.89
2.17
1.51
1.80
0.92
1.58
2.23
2.38
3.13
2.24
1.89
2.55
2.51
1.13

Note: S = Steel structure, CFT = Concrete-filled tube columns.

Spectral responses at building sites
Fig. 1 shows the response spectra of the base acceleration records of both x- and y-directions, thedamping ratio of 5% is used. The nine buildings are located in Shinjuku ward, Chiyoda ward, Bunkyo
ward, Minato ward, and Meguro ward of Tokyo. As can be seen from Fig. 1, response spectra havesmall coefficient of variation of about 0.2 at the middle to long period range.
In view of the strong randomness of earthquake motions, the intensity and characteristics of these
input earthquake motions may be considered as similar ones. Consequently, it is reasonable to use theaverage to represent the input earthquake level in this area. In one sense, it could be considered that
all the nine buildings were subjected to a common ground shaking characterized by the average
spectral plots.
It should be also noted that in Tokyo and Osaka city relatively far from the epicenter, long-period
earthquake motions were observed during the 2011 Great East Japan Earthquake. The spectral
characteristics in Tokyo differed considerably from the well-known motion recorded during the 2004
Niigata Chuetsu Earthquake. As partly shown by Fig.1b, the spectral velocity was almost uniform forthe vibration periods from 0.5s and 20s, and its magnitude exceeded even the largest spectral value
due to the 2004 Niigata Chuetsu Earthquake that concentrated at the period about 7s (not shown).
Thus, unlike the responses during the 2004 quake, the responses of the tall buildings in Tokyo
were dominated by not only the long period motion but also the shorter period motions during the2011 Great East Japan Earthquake.
Amplification of acceleration
The ratio of accelerations of top to base will be named as “acceleration amplification ratio”. In Fig. 2,
its value is shown with respect to each building height. In addition to the nine buildings of 14-story or
higher discussed above (Table 1), two shorter response-controlled buildings with steel dampers and ten
short to tall seismically-resistant buildings (Kasai 2011a) are added for comparison over wide range.

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Average
Average ± Standard deviation
Individual motion

400

(c)

30
Displacement (cm)Displacement(cm)

Pseudo-acceleration(cm/s/s)
Pseudo-Acc. (cm/s2)

35

(a)

500

300
200
100

25
20
15
10
5

T(s)

T(s)
0

0
1

2

3

4

0

5

1

2

3

(b)
加速度増幅比(頂部/基部)
Acc. Amplification(Top/Base)

Pseudovelocity (cm/s) (cm/s)
Pseudo-Velocity

0

60
50
40
30
20
10

T(s)
0
0

1

2

3

4

●

5

Fig. 1. Response spectra ((a) to (c)) generated
from the base motions of the nine buildings(damping ratio 5%).

5

Seismic-resistant building

耐震構造

制振構造
□ Response-controlledbuilding

432
1

Number of Stories

0
0

5

4

10

20

30

40

50

60

Fig. 2. Acceleration amplification factor vs.
number of stories of buildings

As stated in the previous section, the response spectra for the buildings are similar, and thevibration period of the building is well correlated to its height. However, acceleration amplification
ratio in Fig. 2 does not follow the trend of acceleration spectra in Fig. 1a: It is very high for tallerbuildings, in contrast to low spectral accelerations in Fig. 1a (Kasai, 2011a,b).
This is due to significant contribution of higher modes as will be explained in later sections, and,in case of seismic-resistant buildings, their damping ratios below the value of 5% used in the spectraof Fig. 2. Note also the shorter response-controlled buildings with steel dampers show similar trend as
the seismically-resistant building, since damper was elastic or yielding very little for the level of theground shaking in Tokyo.
In Japanese practice to-date, design criteria for response-controlled buildings have been set for
displacement control, and rarely for acceleration control. In spite, excessive accelerations have beenfound to cause large economic loss due to the damage on non-structural components and facilities.
Thus, acceleration amplification such as shown in Fig. 2 should be taken in structural design more
seriously. By this reason, the following discussion will refer to both displacement and acceleration.
Calculation of displacements
By using the following two different methods, the displacements of structure are calculated from therecorded accelerations. The results are compared with each other in order to confirm their reliability(Kasai, 2011a).
Method 1 performs double integration together with hi-pass filtering in frequency domain. The
cut-off frequency is typically 0.05 or 0.1Hz. Method 2 first obtains modal properties such as vibration
period, damping ratio, and participation vector, by applying a basic system identification technique forthe story where recording was done. Then, the time histories of acceleration and displacement of eachmode are calculated by using the base acceleration recorded, and thus-obtained responses typically formodes 1 to 3 are added together. This is a so-called modal superposition analysis, and is conductedeasily, without modeling numerous structural elements of the building.

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For all the nine buildings considered, the displacements from method 2 agreed well with thosefrom method 1, and accelerations from method 2 agreed with those recorded. In such cases, the modal
properties obtained are considered valid, and the contribution of each individual mode to the total
response of system, and the effect of damping can be furthermore examined.
Note that method 2 is based on the assumption of linear response, proportional damping, and real
number mode. The agreement between the two methods suggests that the buildings had linear orslightly nonlinear behavior during the earthquake as well as moderate amount of damping. In thenext sections, four selected buildings will be considered to describe in detail typical responses andmodal contributions.

PERFORMANCE EXAMPLES
Building 1 (seismically-resistant conventional structure)
Building 1 is a seismically-resistant 29-story steel building constructed in 1989 (Hisada et al. 2011,2012). It is a school building of Kogakuin University, located in Shinjuku ward of central Tokyo. The
building height is 143 m, and floor plan dimension is 38.4 and 25.6 m in EW and NS directions,
respectively. See Hisada et. al. (2011, 2012) for the building details and sensor locations.
As indicated in Table 1, the peak accelerations in x- and y-directions were 91 and 89 cm/s2 at thebase, and 235 and 316 cm/s2 at the top floor, respectively. The acceleration amplification ratios are
2.58 and 3.55, respectively. The average drift angle (i.e., top floor displacement divided by the height)
is 1/350 rad., and the structure remained elastic. The vibration periods for the first three modes are
2.96s, 1.00s, and 0.52s for x-direction, and 3.10s, 0.94s, and 0.47s for y-direction, respectively.
Likewise, damping ratios are 1.7%, 1.8%, and 3.4% for x-direction, and 2.1%, 1.6%, and 3.4% for
y-direction, respectively. Prof. Hisada of the University reported damping ratio of 0.01, based on thesmall amplitude vibration test which he conducted before 2011 ( Hisada 2011).
Fig. 4 top shows y-direction pseudo-acceleration response spectra Spa of Building 1 (building
acceleration spectrum, solid line) and a component at building top floor (component acceleration
spectrum, broken line) due to the y-direction accelerations recorded at the building base and top floor,
respectively. Damping ratios are set to 2% and 3%, considering responses of building andnon-structural component such as ceiling (Kasai 2011b), respectively. Similarly, Fig. 4 bottom shows
displacement spectra Sd of Building 1 (building displacement spectrum, solid line) and a component(component displacement spectrum, broken line), respectively. The two vertical axes on two sides ofeach figure are in reference to responses of the Building 1 and the component, respectively.
Spa’s of Building 1 at the 2nd (0.94s) and 3rd (0.47s) mode periods are large, suggesting possible
higher mode contributions to the accelerations in the building. Also, Spa’s of components resonant withthe 1st (3.09s) and 2nd (0.94s) modes are extremely high, and their values are 1,600 and 2,400 cm/s2,
respectively. Time history analyses of such components have indicated many cycles of large
accelerations.
On the other hand, Sd’s of both Building 1 and component are highly dependent on the building’s 1st
mode period (3.09s). Note that broken line in Fig. 4 bottom indicates the component may move 400cm,
if it is flexible and resonate with the building’s 1st mode.
According to Hisada et al. (2011, 2012), moving of furniture, falling of ceiling and books occurred
due to the high acceleration. The control of building’s higher mode responses is a problem that needs
to be resolved in case of a conventional seismically-resistant tall building (see also later sections).
Fig. 5a compares acceleration records at top floor and base in y-direction. The earthquake duration
is long, and is considered to be about 200 seconds (Fig. 5a). For the first 90 seconds of the figure, highfrequency response of the top floor is apparent, as confirmed by the large number of cycles per unit
time. These are caused by the high-frequency ground shaking, as shown by the base accelerations. In
contrast, for the last 110 seconds, low frequency response is dominant. The ground shaking is weak(Fig. 5a), but its low frequency contents excited the first mode and caused resonated response.

1103

Fig. 5b compares the top floor acceleration recorded with that calculated by method 2. The good
agreement suggests that the mode method is effective, and the first three modes are adequate in
response calculation for this case. Fig. 5c compares relative displacement of top floor obtained bydouble integration of the record (method 1) with that calculated by method 2. In some cycles the peakvalues by the both method differ a little, but the displacements agree well overall.
As is known, the contribution of each vibration mode depends on the type of response as well as
the story level determining participation vector. Since the properties and responses of each vibration
mode have been obtained, it is possible to discuss such contributions:Fig. 6a shows the acceleration of each mode at the top floor. As mentioned earlier, it is dominatedby the 2nd, 1st, and 3rd modes in the order of weight for the first 90 seconds. For the later 110 seconds,
the 1st mode response increases and become dominant, with slight contribution from the 2nd mode. As
Fig. 6b shows, for the 16th floor the 2nd mode is much more dominant, developing almost the sameacceleration as top floor. As for the displacement at top floor (Fig. 6c), the 1st mode dominates
throughout the entire duration.
Component
Spa (cm/s2)(a)T2=0.94s

T3=0.47s

T1=3.09s

Building
Spa (cm/s2)

T(s)Building
Sd (cm)Component
Sd (cm)Fig. 3.

Building 1

T1=3.09s

T2=0.94s

T3=0.47s(b)

Fig. 4 Response spectra of Building 1 (solid lines)
and component at top floor (broken lines).

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T(s)

Top acceleration

High Frequency

Base acceleration

Low Frequency(a) Accelerations recorded at top and base.
Mode superposition
Actual Acc.

(b) Comparison: acceleration obtained by mode superposition vs. actual recorded acceleration.
Mode superposition
Double integral of actual acc.

(c) Comparison: dispt. obtained by mode superposition vs. double integral of recorded acceleration.
Fig. 5. Records and accuracy of mode superposition method.

2nd mode
3rd mode

1st mode(a) Modal contributions to top floor acceleration.
2nd mode
1st mode

3rd mode(b) Modal contributions to 16th floor acceleration.
3rd mode

1st mode

2nd mode(c) Modal contributions to top floor displacement.
Fig. 6. Contributions of the first three modes to acceleration and displacement of Building 1.

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Buildings 4, 6, and 9 (response-controlled structures)
Building 4 is a 21-story government office building (Koyoma and Kashima 2011, Kasai 2011b). It
consists of a steel frame and 336 low yield point steel (wall) dampers and 284 viscous (wall) dampers(Fig. 7a). For seismic energy dissipation, the steel damper utilizes yielding of steel material, andviscous damper utilizes flow resistance of the polymer liquid with high viscosity (Kasai et al. 2009).
Note that a contrasting case of using only steel dampers lead to large accelerations like theseismically-resistant building in the previous section, since the damper remained elastic for the levelof shaking in Tokyo (Kasai et al. 2011b). Building 4 had been designed to avoid such a situation,
expecting that viscous damper would dissipate energy from a small earthquake, and steel damper, themost economical among all types, would dissipate considerable amount of energy at a large quake,
respectively.
Building 6 is a 41-story office building (Kasai et al. 2009, 2011b). It consists of a frame using
concrete-filled tube columns and steel beams, and 688 oil dampers (Fig. 7b). For energy dissipation,
the damper utilizes flow resistance of oil with low viscosity. The valve placed at orifice is shaped to
produce the force linearly proportional to velocity, but a relief mechanism to limit the force is provided,
making the hysteresis to switch from an elliptical shape to a rectangle shape. Most likely, the relief did
not occur for the level of shaking.
Building 9 is a 54-story office steel building constructed in 1979. It was retrofitted in 2009
(Maseki et al. 2011) by attaching 288 oil dampers (Fig. 7c). 12 dampers per floor were attached to
middle 24 stories of the building. The oil damper is similar to those used for Building 6, except that its
relief mechanism is modified to reduce forces near peak responses. This aims to reduce the axial
force of the column transmitting the damper force, and consequently uplift force of foundation. Most
likely, however, the relief did not occur for the level of shaking.
21-story Building:

41-story Building:

Steel Frame +336 Steel Dampers +284 Viscous Dampers

Steel Frame +688 Oil Dampers
45.4m

54-story Building:
Steel Frame + 288 Oil Dampers
42m

63m

45.4m

52m

96m

223m

186.9m
99.6m

Y

Steel
Damper

X

(a)

Y

X

(b)

Y

X

Viscous
DamperOil
DamperOil
DamperFig. 7. Response-controlled buildings and dampers considered (Buildings 4, 6, 9 from left).

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(c)

As indicated in Table 1, average of acceleration amplification ratios of Buildings 4, 6, and 9 is lessthan 2, well below those of Building 1, and they remained elastic. Modal properties are obtained frommethod 2, and estimated 1st mode damping ratios are about 4%, and those of the 2nd and 3rd modes
are almost equal or larger. The 1st mode vibration periods are indicated in Table 1, and those up to
the 3rd mode will be mentioned later.
For all the three buildings, their accelerations and displacements are obtained from superposition
up to the 3rd mode, and accuracies are confirmed as in to be even better than those shown in Figs. 5band c shown earlier. Such responses at top floor are shown by black lines in Figures 8, 9, and 10 forbuildings 4, 6, and 9, respectively.

(a) Acceleration of top floor(b) Displacement of top floor

Decreased damping (1%)

Original damping

Decreased damping (1%)
Original damping

Fig. 8. Building 4 with different damping ratios (y-dir.).
(a) Acceleration of top floor(b) Displacement of top floor

Decreased damping (1%)

Decreased damping (1%)

Original damping

Original damping

Fig. 9. Building 6 with different damping ratios (x-dir.).

(a) Acceleration of top floor

Decreased damping (1%)
Original damping

Decreased damping (1%)(b) Displacement of top floor

Fig. 10. Building 9 with different damping ratios (y-dir.).

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Original dampingIn these three buildings, the acceleration (Figs. 8 to 10) is dominated by the 2nd and 3rd modes forabout 100 seconds, and by the 1st mode for later 200 seconds. Whereas, the displacement (Figs. 8 to10) is dominated by the 1st mode throughout the shaking.
This trend is like that of seismically-resistant Building 1, but the amplitudes are believed to besmaller due to the supplemental damping. Thus, the responses are compared with those of lower but
possible damping ratio representing a hypothetical case of not using the dampers. The modal period is
unchanged, assuming small stiffness of the damper. The 1st to 3rd mode damping ratios are uniformly
set to 1% and superposition is repeated. The results are shown by gray lines in Figs. 8, 9, and 10 for
Buildings 4, 6, and 9, respectively.
In all the three buildings, their responses are considerably smaller (black lines) than those with low
damping (gray line). The peak accelerations and displacements are about 0.5 and 0.7 times those of the
low damping case. Moreover, between significant ground shakings, the responses decay much faster,and number of large cycles is reduced considerably. These help reducing damage and fatigue ofstructural and non-structural component as well as fear or discomfort of the occupants. In order toquantify such an effect, root mean square of the acceleration and displacement at top are calculated,
and their values appear to be about 0.4 and 0.5 times those with low damping, respectively.

COMMENTS ON ACCELERATION AND NONSTRUCTURAL DAMAGE
Inertia forces against structural and non-structural components including equipment and building
content are produced by accelerations in the building. Large accelerations typically developed at upper
stories cause falling, overturning, shifting, crashing, rapture, and excessive vibration of a variety of
non-structural components.
As a matter of fact, economic loss due to damage of non-structural components is much more thanthat of structural damage. Falling of ceilings and other components may also cause death of occupants.
Such failures due to the 2011 Great East Japan Earthquake were enormous.
Figure 11 shows component acceleration spectra for the top floors of the four buildings 1, 4, 6, and9. Damping ratio of the component is assumed to be 3%. The value attached to “original damping” isthe first mode damping ratio. For Building 1 (Fig. 11a) that is seismically resistant, the broken line isbased on the recorded top floor acceleration of the original building having low damping ratios asmentioned earlier, and solid line shows a case where the building damping ratios of the first threemodes are increased to 4%. In contrast, for Buildings 4, 6, and 9 (Fig. 11b-d) that are
response-controlled, the solid line is based on recorded top floor acceleration of the original building(Figs. 8 to 10), and the broken line shows when the first three modal damping ratios of the building are
reduced to 1%. These examine a merit of increasing building modal damping ratios for protecting theacceleration-sensitive components.
According to Fig. 11, the past belief that short-period components are safer in a tall building isincorrect. They are as vulnerable as the long-period components due to multiple resonance peaks
created by different modes of the building. The peaks are extremely high, even greater than 2,000
cm/s2 (≈2G). Thus, the resonant acceleration of the components may be greater than 8G at a so-called
major quake 4 times or stronger. The problem may become more serious when damage and softeningof components cause period shifting from one resonance peak to others. Note that three peaks for eachbuilding are shown in Fig. 11, since the first three modes were identified. But more peaks may emerge
in an actual low damping case.
As a rule of thumb, facilities may overturn when floor acceleration exceeds 0.3G, and ceilingwhose vibration period typically ranges from 0.3s to 1s may fall when its acceleration response
exceeds 1G. These indicate the needs for an immediate attention to component responses at a major
quake that will occur in Tokyo. Fig. 11 also clearly indicates that even moderately increasing thebuilding damping ratio by 3% or so would reduce the component acceleration considerably.

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Original Bldg.
Damping (2.1%)(c) Bldg. 6
Spa (cm/s2)

Spa (cm/s2)(a) Bldg. 1
Increased Bldg.
Damping (4%)

Decreased Bldg.
Damping (1%)

Original Bldg.
Damping (3.4%)T(s)Decreased Bldg.
Damping (1%)

Original Bldg.
Damping (3.7%)(d) Bldg. 9
Spa (cm/s2)

Spa (cm/s2)(b) Bldg. 4T(s)Decreased Bldg.
Damping (1%)T(s)

Original Bldg.
Damping (3.9%)T(s)Figure 11. Component response spectra (component damping ratio = 3%).

CONCLUSION
Responses of the tall buildings in Tokyo during the 2011 Great East Japan Earthquake are discussed
based on the strong motions recorded. By successfully analyzing contributions of multiple vibration
modes, various shaking phenomena in the tall building that had not been experienced are clarified.
Based on this approach, the merit of damping technology for occupants and contents in the tallbuilding is explained. Immediate attention must be given to the acceleration-induced hazard in tallbuildings, considering much stronger shaking likely to occur in the near future.

REFERENCES
Kasai, K. (2011a). 4.2.3 Acceleration records of buildings, 4.4.5. Behavior of response controlledbuildings, Preliminary Reconnaissance Report of the 2011 Tohoku-Chiho Taiheiyo-Oki Earthquake,
Architectural Institute of Japan, pp.280-284, pp.345-347.
Kasai, K. (2011b). Chapter 4. Performance of Response-Controlled Buildings, The Kenchiku Gijutsu,
No.741, pp.118-123.
Hisada, Y., Kubo, T., and Yamashita, T. (2011), Shaking and Damage of the Shinjuku Campus
Building and Shinjuku Campus Report from Kougakuin University, Internet Access:
http://kouzou.cc.kogakuin.ac.jp/Open/20110420Event/20Apr11_Kogakuin01.pdf
Hisada, Y., Yamashita, T., Murakami, M., Kubo, T., Shindo, J., Aizawa K., and Arata T. (2012),
Sesimic Response and Damage of High-Rise Buildings in Tokyo, Japan During the Great East Japan
Earthquake, Proceedings, International Symposium on Engineering Lessons Learned from the Giant
Earthquake, Tokyo, Japan, March 3 -4.
Koyama, S., and Kashima, T. (2011). Prompt Report on Strong Motions Recorded during the 2011
Tohoku Pacific Ocean Earthquake, Report 5, Building Research Institute (BRI).
Kasai, K., Motoyui, S., Ozaki, H., Ishii, M., Ito, H., Kajiwara, K., and Hikino, T. (2009). Full-Scale
Tests of Passively-Controlled 5-Story Steel Building Using E-Defense Shake Table; Part 1 to Part 3,
Proc. Stessa2009, Philadelphia.
Maseki, R., Nii, A., Nagashima, I., Aono, H., Kimura, Y., and Hosozawa, O. (2011). Performance ofSeismic Retrofitting of Suoer High-Rise Building Based on Earthquake Observation Records,
International Symposium on Disaster Simulation and Structural Safety in the Next Generation(DS’11), Japan1109