Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanEVALUATION OF EARTHQUAKE RESPONSE OF
HIGH-RISE BUILDING WITH DAMPERS IN SENDAIDURUING THE 2011 OFF THE PACIFIC COAST OFTOHOKU EARTHQUAKE
Wataru GOTO1, Toshiya MOTOHI1, Yoshifumi SUGIMURA1, Shigeto NAGASHIMA1,
Kozo TOYOTA1, Mikio SUZUKI1, Hiroshi DOHI2 and Kenji SAITO3
1

Research and Development Department, NTT Facilities, INC. ,Tokyo, Japan, gotouw23@ntt-f.co.jp
2
Dr.Eng, Corporate Planning Department, NTT Facilities, INC. ,Tokyo, Japan, dohihi22@ntt-f.co.jp
3
Dr.Eng, Building Engineering Department, NTT Facilities, INC. ,Tokyo, Japan, saitou23@ntt-f.co.jp
ABSTRACT: In the 2011 off the pacific coast of Tohoku Earthquake (M9.0) which
occurred on March 11, the strong shaking in buildings were observed in wide range areasof the whole country. In this paper, vibration characteristics and seismic performance ofbuilding are evaluated using observed strong motion records in a high-rise building in
Sendai, which is the closest to the epicenter. And, vibration control effect with dampers
and damping capacity of the building are confirmed.
Key Words: the 2011 off the pacific coast of Tohoku Earthquake, observed strong
motion, microtremor, seismic response, natural period, damper

INTRODUCTION
The authors have continued seismic observation in nationwide since 1956. As of February 2012, 69
buildings throughout Japan are subject to seismic observation (Fig. 1), configuring the seismic
observation network mainly with the structurally-distinctive buildings including those located in theincreased risk of earthquakes, base-isolated buildings or structural control buildings, and buildings inwhich a high iron tower is incorporated. Each building is equipped with accelerometers on the bottom,
intermediate and top floors as well as on the iron tower. Using this seismic observation network,strong motion records have been observed including records of the Southern Hyogo prefectureearthquake in 1995, Miyagi earthquakes in 2003 and 2005, the Mid Niigata Prefecture Earthquake in
2004. In this network, not only ground shaking but also shaking at multiple points in buildings are
simultaneously observed, so this allows to obtain estimation of vibration characteristics of buildings
and vibration evaluation of equipment, which are based on seismic observation records. And, byobserving not only huge earthquakes but also small and medium earthquakes and microtremor,

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changes in vibration characteristics by differences in level of amplitude and across ages are evaluable.
In the 2011 off the pacific coast of Tohoku Earthquake (M9.0) which occurred on March 11, thestrong shaking were observed in wide range areas of the whole country. At that time, 64 buildings areoperated in this network. Main shock records are observed on 29 buildings, and a building furthest to
this quake’s epicenter is located more than 1250 km away (Fig. 2). The maximum acceleration of over
500 gal is observed in the building in Sendai which is the closest to the epicenter. It is also confirmedthat high-rise buildings in Tokyo located about 400 km away from the epicenter are swaying for morethan 10 minutes with the maximum amplitude of over 100 cm on the top. These seismic response
records are considered valuable for evaluation of not only seismic performance and damage ofbuildings in a huge earthquake but also vibrations of buildings in long-period ground motion.
This reports focus on a high-rise building in Sendai. In this earthquake, this building which isequipped with dampers has been undamaged, but provided useful data indicating the building behavior
during a huge earthquake. In this paper, this building is showed as an example that the damper
functions effectively, and vibration characteristic and seismic performance of building is evaluatedusing observed strong motion records in a high-rise building in Sendai. And, vibration control effectwith damper and damping capacity of the building is confirmed.

Fig. 1 The seismic observation network

Fig. 2 Observation records of the 2011 off the pacific coast of Tohoku Earthquake

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OVERVIEW OF THE BUILDING
The intended building is located about 175 km from the epicenter. This building is a high-rise building
equipped with the RDT (Rotary Damping Tube) and LED (Lead Extrusion Damper) as dampers, andhas an iron tower. Additionally, the building is equipped with accelerometers for the purpose of
figuring out building behavior at time of earthquakes, which have produced a number of records since
the building completion in 2004. Servo-type accelerometers (resolution of 24 bit) that enablemeasurement in the three directions of X, Y and Z are installed on the second basement, ground and22nd floors as well as on the top of the iron tower. The X direction is the longitudinal beams, and the
Y direction is the transverse beams. Fig. 3 shows the locations of accelerometers in the building.
Triggered by the accelerometer on the second basement floor, seismic observation starts
simultaneously with the accelerometers installed on the relevant floors when the second basement
floor exceed 1.0 gal. The sampling frequency and range of measurement are set to 100 Hz and ±2,097
gal, respectively. The data observed during the 2011 Tohoku earthquake were recorded for more than
one hour.
Z35

107,400

Z21

Z10

Under
G.L.
Above G.L
TOWER

Z5

51,200

Seismograph

Y6
Y5

LED
RDT

Y4

N

6,400 6,400 6,4006,400 6,4006,400 6,400 6,400

X3 X4 X5 X6 X7 X8 X9 X10 X1176,700Z1
Z2

Y（N344°E）
8,000

Z23

15,850Z25

Type:servo‐type accelerometer
Component:two horizontal , vertical
RDT Sampling frequency :100Hz:±1,000gal～±2,000gal
LED Range
Resolution:16～24bit
Trigger:1.0gal53,500Z27

Strong motion observation system

23,85042,200

Seismograph

X(N74°E)

X3 X4 X5 X6 X7 X8 X9 X10 X11

Fig. 3 The locations of accelerometers in the building

ANALYSIS OF OBSERVATION RECORDS
In this section, the characteristic of observed seismic waves is analyzed by comparing the records
obtained from before and after the earthquake and from near buildings.
Observed seismic waves
Fig. 4 shows the observation record at the second basement. The maximum acceleration in the X
direction is 158.5 gal, and that in the Y direction is 257.5 gal. The seismic wave contains two peaks,
and this has the reason that seismic shift have occurred in two area, both of them are located in off
Miyagi prefecture. Fig. 5 shows the records observed in Kobe city during the Southern Hyogo
prefecture earthquake in 1995. The comparison between Fig. 4 and Fig. 5 shows that big shakes during
the 2011 Tohoku earthquake continue for a surprisingly long time.

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Max, 158.4

Acc. (gal)

300
150
0
‐150
‐300

50

Acc. (gal)

300 0
150
0
‐150
‐300
0

50

X dir.
100

150
Time (s)200

250

Y dir.

Max, 257.5
100

300

150
Time (s)

200

250

300

Fig. 4 The observation record at the second basement

Acc. (gal)

400
200
0

NS

‐200
‐400

Acc. (gal)

400

0

50

100

150
Time (s)

200

250

300

200
0
‐200

EW

‐400
0

50

100

150
Time (s)

200

250

300

Fig. 5 the records observed in Kobe city during the Southern Hyogo prefecture earthquake in 1995

Spectral analysis
Using the records of the 2011 Tohoku earthquake, the response spectrum was calculated. Fig. 6 shows
the comparison of the response spectrum of the largest earthquake ever observed in the building before
the 2011 Tohoku earthquake (the Miyagi earthquakes in 2005) and the Southern Hyogo prefectureearthquake in 1995, and the design basis spectrum in Japan (Level 2). As seen in Fig. 6, the 2011
Tohoku earthquake is much larger than the earthquake ever observed, and this is slightly smaller thanthe design basis spectrum in Japan, but it exceeds in some periodic bands. Otherwise, the spectrum isgenerally smaller than that of the 1995 Hyogo earthquake, and this difference is remarkably seen inaround the periodic band from 1.0 seconds to 2.0 seconds, which may cause particularly building
damage.
Also, Fig. 7 shows the comparison of the response spectrum of the intended building with recordsof K-NET on free field in Sendai and BRI located about from 250 m away from the building. The
ground condition of the intended building is relatively suitable, and it is considered that the difference
from the record of K-NET is caused by the difference of ground conditions. The record of the intended
building is well accorded with BRI.

1080

250

2011 TOHOKU-X
2011 TOHOKU-Y

Sv（5%） [cm/s]

200

2005 MIYAGI X
2005 MIYAGI Y

150

KOBE NS
KOBE EW100

The design basis(Level 2)

50

0
0.1

1
Period [s]10Fig. 6 The comparison of the response spectrum with other earthquakes
300

The intended build.-X
The intended build.-Y

250

Sv（5%） [cm/s]

BRI-X
BRI-Y

200

K-NET EW
K-NET NS

150
100
50
0
0.1

1
Period [s]10Fig. 7 The comparison of the response spectrum with other points

VIBRATION CHARACTERISTICS OF A BUILDING
Based on the records of observation multiple points in the intended building, vibration characteristics
are identified. And the effects that may influence vibration characteristics are considered. This section
presents a comparison of the records with 3 seismic observation records of a foreshock on May 9 in2011, the maximum aftershock on April 7 in 2011 and the Mid Niigata Prefecture Earthquake in 2004.
The specifications of earthquakes are shown in Table 1.
Table 1 The specifications of earthquakes
Seismic source information
No.

Date and Timeof occurrence1

2004/10/23 17:56:00

37.29

138.872

2011/03/09 14:45:12

38.20

3

2011/03/11 14:46:18

38.10

4

2011/04/07 23:32:43

38.20

Northern
East
Depth
latitude longitude (km)Mj

Epicenter location

Maximum Acceleration(The second basement)
X

Y

13.08

6.8 the Mid Niigata Prefecture143.178.00

7.3 Off the Coast of Sanriku

15.3

18.2

142.8623.74

9.0 Off the Pacific coast of Tohoku

158.4

257.5

141.92

65.89

7.1 Off Miyagi Prefecture

131.8

186.0

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5.4

5.7

The design natural frequency
The design natural periods of the building are 2.97 seconds on the X, and 3.26 seconds on the Y
direction, which is shown as Table 2. Then Fig. 8 shows the relations of the response spectrum andnatural frequency of the 2011 Tohoku earthquake. In this earthquake, the seismic wave of the X
direction contains many components with around a period of 3 seconds, and it is thought that a slightly
severe seismic force works on the X direction of the building. As for the wave in the Y direction, it
contains many components with a period of 2 seconds and under, and it is considered that the seismic
wave is excited in higher-order modes.

Table 2 The design natural periods of the building (sec)Direction
X
Y

1st.
2.973
3.260

2nd.
1.012
1.110

3rd.
0.606
0.678

150

Sv（5%） [cm/s]

X dir.–1st100

Y dir.–2nd
Y dir.–3rd

50

X dir.–2nd0
0.1

X dir.–3rd

Y dir.–1st1Period [s]10Fig. 8 The relations of the response spectrum and natural frequency

Estimation of the natural frequency
The building natural frequency is estimated based on the seismic observation record. The building
transfer function is calculated using the records of the ground floor and the highest floor (22F). A peakof the calculated transfer function is defined as the estimated building natural frequency. The
calculated transfer function from each earthquake record is shown as overlaid curves in Fig.9. In The
2011 Tohoku earthquake, the natural periods are equivalent to the design value of about 2.8 seconds in
the X and about 3.2 seconds in the Y direction. In the aftershock, the natural periods are about 2.8
seconds in the X and about 3.2 seconds in the Y direction, on the other hand in the foreshock, they areabout 2.4 seconds in the X and about 2.9 seconds in the Y direction, which become rather small. In theearthquake in 2004, they are about 2.2 seconds in the X and 2.7 seconds in the Y direction, whichbecome much smaller than those. As shown in Table 1, the acceleration levels of the earthquake in2004 and the foreshock are very small compared with those of the main shock and the aftershock. The
amplitude dependence of the natural periods of the building estimated from seismic observation
records has been confirmed.

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100

100

Y dir.
Transfer function

Transfer function

X dir.
10

1

No. 1
No. 2
No. 3 (The 2011 Tohoku)
No. 4

0.1
0

1

2

Period (s)

3

4

10

1

No. 1
No. 2
No. 3 (The 2011 Tohoku)
No. 4

0.1
5

0

1

2

Period (s)

3

4

5

Fig. 9 The comparison of transfer function from each earthquake

TIME-SERIES EVALUATION OF THE NATURAL PERIODThis section considers considered changes in the natural periods focusing on vibration characteristics
over time. Vibration characteristics of the 2011 Tohoku earthquake (the main earthquake) and those
before and after the main earthquake are arranged in chronological order, and the tendency is
considered.
Evaluation in chronological orderFig. 10 shows vibration characteristics of the 2011 Tohoku earthquake (the main earthquake) and those
before and after the main earthquake in chronological order. In the intended building, microtremor
records are is observed periodically since more than 3 years from before the main earthquake, and so
the natural periods estimated from the microtremor observation records are is also shown. The figure
presents the increased natural periods in the main earthquake and the maximum aftershock both in the
X and Y directions which returned to the original values. And, it is confirmed that the average of thenatural periods estimated from observation records observed of before the main earthquake are slightly
larger than that of after the main earthquake. This tendency is similar to the natural periods estimatedfrom microtremor observation records.
The maximum aftershock
The main earthquake

3.5

2.5

The average of after

Period (s)Period (s)33

The average of before
2
0

5

10

Microtremor

15
20
25
Chronological order

30

2.5
35

0

5

10

15
20
25
Chronological order

30

35

Fig. 10 The natural periods in chronological order

SEISMIC RESPONSE ANALYSIS
Using the records of the 2011 Tohoku earthquake, the earthquake response is was analyzed with athe space frame elasto-plastic model of the intended building. The natural periods of the building is
was adjusted by the superimposed load or the member stiffness, based on the natural periods and1083

building conditions estimated from observation records. Table 3 shows analytical parameters of thebuilding and dampers. The observation records from the second basement are were used as the input
wave.
Fig.11 shows the comparison of the maximum response of each floor based on the observation
records and the analysis. In the X direction, the acceleration and the displacement generally agree withboth responses. But in the Y direction, the responses of the analysis result become smaller than theobservation record. Fig. 12 shows the comparison of the displacement response waveforms on the
22nd floor and the iron tower top with the observation records. Looking at the time history of thedisplacement response shown in Fig. 12, the waveforms as the analysis result roughly represented theobservation results and ensured the analysis model could reproduce the actual phenomenon. Fig. 13
shows relations between the velocity and the damping force of RDT, and between the displacement
and the damping force of LED in the story where the maximum relative story displacement is thelargest. It is apparent that RDT provided the sufficient damping performance up to 75 percent of thedesigned damping force and LED provided the sufficient damping performance by becoming plastic.
Fig. 14 shows the time history of absorption energy obtained from analysis analyzed. The absorptionenergy of dampers consists about 73 percent in the total. It is confirmed made sure that the absorptionenergy become greatly enlarged just before about 100 seconds when the building amplitude isincreased, and also at the same time the building vibration amplitude is dampened. The analysis result
verified that the dampers provided the sufficient damping performance, and the building issafeguarded against the earthquake.
Table 3 Analytical parameters of the building and dampers
Analysis Model

Space frame elasto-plastic analysis model
36 layered
Layer Number(Above G.L. = 34, Under G.L. = 2)
Column & Beem Beam element with rigid-plastic edge
Lead extrusion damper
Member Model-> Elasto-plastic spring model
DamperRotarydamping tube-> Maxwell modelh = 1.0 %Viscous damping factor of frame(Proportion to instantaneous stiffness)

X
540.8

Z33

Z31

Z31

Z29

Z29

Z27

Z27

Z25

Z25

337.6

Z23
Z21

Z19

Z19

STORY

STORY

Z21
Z17
Z15

Z13

Z11

Z11

Z9

Z9

Z7

Z7

Z5

Z5

Z3

Z3

Z1

210.5
158.4
500
1000 1500
Max. Acc. (cm/s2)

0

Z1
-Z1
2000 0

Z27
Z25

Z27
Z25
45.3

Z23
Z21

Z13
Z11

Z9
Z7

Z9
Z7

Z5
Z3

Z5
Z3

2000

0.4
0.0
0

50

Z1
0.5
-Z1 0.0
100 0Max. Disp. (cm)Fig. 11 The comparison of the maximum response

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37.6

Z19
Z17
Z15

Z13
Z11

Z1
-Z1

312.3
257.4
500
1000 1500
Max. Acc. (cm/s2)

Z31
Z29

Z19
Z17
Z15

50.5

Z35
Z33

Z31
Z29

Z23
Z21

444.0

Z15

Z13

-Z1

1866.0

Z17

Y
50.9

Z35
Z33

STORY

Z33

Z23

X

Y
Z35

STORY

Z35

50
Max. Disp. (cm)100

Disp. (cm)Observation

Analysis

0
‐40
‐80
80 0
40
0
‐40
‐80

50

100

150
Time (s)

200

250

300

0

50

100

150
Time (s)

200

250

300

Disp. (cm)The iron tower top

80
40
0
‐40
‐80
80 0
40
0
‐40
‐80

50

100

150
Time (s)

200

250

300

Disp. (cm)Disp. (cm)The 22nd floor

80
40

0

50

100

150
Time (s)

200

250

300

Fig. 12 The comparison of the displacement response
2000
Damping force (kN)

RDT

1000
0

75 %

-1000

The designed damping force

-2000
-200

-100
0
100
Velocity (mm/s)

LED

1000
0
-1000
-2000

200

-30

-15
0
15
Dispracement (mm)Fig. 13 The damping force
80000
Absorption energy (kN*m

Damping force (kN)2000

Vibration

60000

RDT

40000

73 %

LED
Viscous damping
25 %of frame

20000
0
0

50

100

150

200

Time(s)Fig. 14 The time history of absorption energy

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250

300

30

CONCLUSIONSIn this report, vibration characteristics and seismic performance of building are evaluated using
observed strong motion records in a high-rise building in Sendai during the 2011 off the pacific coastof Tohoku earthquake. The result obtained about the seismic excitation and seismic response is besummarized the following.
1) The seismic motion is slightly smaller than the design basis spectrum in Japan, but it exceeds insome periodic bands, and this is characterized by the long earthquake duration.
2) The natural periods estimated from the main earthquake are larger than ever observed, and these
periods are close to the design natural periods.
3) As a result of using the parameters based on observation records, the building response during
the large earthquake was simulated. The analysis result verified that the dampers provided thesufficient damping performance, and the building is safeguarded against the earthquake.
But effects of higher-order modes and the difference of the natural periods between before andafter the main earthquake hasn’t been figured out in this report.
So, the further study must verify possible causes that could affect the vibration characteristics andclarify them through analyses or other means in order to establish how to accurately estimate thesafety of buildings after the large earthquake.

ACKNOWLEDGMENTS
Strong motion observation records of National Research Institute for Earth Science and Disaster
Prevention, and Building Research Institute are used as records around the intended building. The
authors gratefully acknowledge for NIED and BRI.

REFERENCES
Toyota, K. et al. (2001). “Dynamic Loading Experiment and an Application to a High-rise Building ofLarge-scale Lead Hysteretic Damper. (Part1 to 2)” Summaries of technical papers of annual
meeting Architectural Institute of Japan, Vol. B-2, pp385-386
Saito, K. et al. (2004). “Application of Hybrid Damping System using Hysteresis Damper and Viscous
Damper in Multistory Building.” AIJ Journal of Technology and Design, Vol. 19,pp95-100
Akagi, H. et al. (2004). “Earthquake Observation System for Telecommunication in Japan.” The 13th
WCEE
Tsukuda, S. et al. (2006). “Seismic Response of the Buildings during the Miyagi-ken-Oki Earthquake.
(Part1 to 3)” Summaries of technical papers of annual meeting Architectural Institute of Japan, Vol.
B-2, pp7-12
Goto, W. et el. (2009). “Analysis of Strong-motion Records during the Iwate-Miyagi-Nairiku
Earthquake and Iwate-ken-Engan-Hokubu Earthquake” Summaries of technical papers of annual
meeting Architectural Institute of Japan, Vol. B-2, pp549-550
Nagashima, S. et el. (2011). “Evaluation of Earthquake Response of High-rise Building with Damperin the 2011 off the Pacific coast of Tohoku Earthquake.” Summaries of technical papers of annual
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