Journal of Wind Engineering
and Industrial Aerodynamics 74—76 (1998) 943—953
Full-scale measurements of wind-induced responses
on the Hamamatsu ACT Tower
Koichi Miyashita!,*, Masaru Itoh", Kunio Fujii!, Junichi Yamashita",
Toshio Takahashi#
! Wind Engineering Co., Ltd., 3-29 Kanda-Jinbo-cho, Chiyoda-ku, Tokyo 101, Japan
" Nihon Sekkei, Inc., 29th Fl., Shinjuku I-LAND Tower, 6-5-1, Nishi-Shinjuku,
Shinjuku-ku, Tokyo 163-13, Japan
# PFU Limited, Solid-square Bldg. East tower 580, Horikawa-machi,
Saiwai-ku, Kawasaki-shi, Kanagawa 210, Japan
Abstract
In Japan, most high-rise buildings are equipped with vibration control devices in order to
improve their habitability by reducing wind-induced vibration. The Hamamatsu ACT Tower is
also equipped with active type vibration control devices. For the purpose of confirming the
vibration control effects of these devices, observations of winds and vibrations have been
carried out. This paper reports on the vibration control effects of the devices on wind-induced
vibration, as well as the results obtained from observations of vibration responses of the
building during strong seasonal winds and a typhoon. ( 1998 Published by Elsevier Science
Ltd. All rights reserved.
Keywords: Dynamic response; TAD; Damping ratio; Full scale measurement
1. Introduction
High-rise buildings in Japan are easily swayed by strong winds such as typhoons
and seasonal winds which occur frequently. Due to this, most high-rise buildings are
equipped with vibration control devices in order to reduce wind-induced vibration, as
well as to improve their habitability. The Hamamatsu ACT Tower is one of such
buildings equipped with active type vibration control devices (Tuned Active Damper,
* Corresponding author.
0167-6105/98/$19.00 ( 1998 Published by Elsevier Science Ltd. All rights reserved.
PII: S 0 1 6 7 - 6 1 0 5 ( 9 8 ) 0 0 0 8 6 - 5
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K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
TAD). With the aim of confirming these effects of the devices, wind and vibration
observations have been carried out since September, 1994. This paper describes the
results obtained from those observations.
2. Building outline and observation method
The ACT Tower is shown in Fig. 1. The height at the 45th level above-ground is
212 m. The plane shape above the large set back at the middle level of the Tower is
different from that below it. Low-rise buildings standing in rows predominate in the
vicinity of the Tower with the exception of about ten mid-rise buildings which average
10 floors in height. Flat land reaches for over 10 km around the Tower. To the north
of the building, there are mixed residential districts, fields and gardens. To the south,
a residential area extends for 5 km beyond which lies the Pacific. Wind direction and
velocity are observed using an arrow-shaped wind vane and a three-cup anemometer
(VAISALA WAA15A) both of which are installed on the east and the west side of the
building at a height of 15 m above the roof. The installation positions, where readings
are not influenced by the presence of the Tower, were obtained from wind tunnel tests.
As a result of the observation, it was found that a larger value for the wind speed
among those observed at two locations was the same as the value of the input air flow.
The behavior of the building is observed using accelerometers (VSE11 made by
Tokyo Sokushin) for the measurement of components in directions X, ½ and Z. These
are installed on the plane center of the 28th and 45th floors. The torsional behavior is
observed by using an accelerometer for components in direction ½ installed at the east
end of the same floor. Two accelerometers (SA-175CT made by Tokyo Sokushin) for
components in directions X, ½ and Z are installed for seismic measurements: one on
Fig. 1. Object building.
K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
945
the 1st floor and the other on the 2nd basement level. Accelerometers (SA-355CT
made by Tokyo Sokushin) for components in directions X, ½ and Z are installed at
the depth of 1 m and 45 m. Furthermore, in order to understand the working
conditions of the TAD on the 45th floor, measurements of the control force, displacement and functioning of signals (ON/OFF) for control are carried out. Data is
collected using the Work Station (PFU, A330) and it is also indicated in the table for
the management of the building. Data is collected through the following steps:
1. A/D conversion of data signals is constantly carried out at 100 Hz and the records
obtained over a 10 min period are stored as a set in a file.
2. It can be judged from the file whether or not an earthquake has occurred. When it
is judged that an earthquake has occurred, the objective file and the preceding and
following files are preserved.
3. For statistical analyses of wind-induced vibration, the data sampled at 10 Hz out of
the files observed by the conversion at 100 Hz is used and all that data is stored.
3. Outline of TAD
The TAD (Mitsubishi Heavy Industries) is a semi-active tuned mass damper with
a multi-stepped pendulum system. It works actively in direction ½ and passively in
direction X. The TAD is installed at a point near the center of the 45th floor and at the
east end of the same floor as shown in Fig. 2. It is expected that the TAD has control
effects on torsional vibration. Table 1 indicates the basic properties of the TAD. The
weight of the TAD is set at 0.17% of the weight of the building above ground and at
0.61% of the effective mass ratio.
4. Free vibration test results
A sinusoidal wave was loaded with an amplitude of 10 cm/s2 for a natural vibration
period of the primary mode by using the TAD as an excitation loading machine. The
free vibration wave measured after the excitation stopped is shown in Fig. 3. The
numerical values in the figure indicate the damping ratio obtained from the free
vibration wave (Table 2). It is clear that the control effects of the TAD during the
period of active control are high.
5. Observation results
5.1. Wind speed at observation points
Fig. 4 compares the approximate values obtained by applying the Gumbel distribution to the daily maximum wind speed gleaned from the anemometer located 15 m
above the top of the building during the period from 1 January 1995 to 1 December
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K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
Fig. 2. Outline of TAD.
Table 1
Basic properties of TAD
Installed floor
Added mass weight
Maximum allowable amplitude
Maximum control force
45 F
90 tonf
150 cm (Y dir.), 90 cm (X dir.)
7.5 tonf
1996, using the moment method, with the observed values plotted by the Hazen’s
method. The wind speed with a return period of one year which is obtained from the
approximate line is 33.0 m/s. It is clear that strong winds are present at the observation points.
5.2. Effects of TAD
Fig. 5 shows the time history wave when the TAD operates during a period of
strong seasonal winds. The values indicated in the figure were recorded during
K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
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Fig. 3. Time history of response acceleration of free vibration.
Table 2
Damping ratio of ½ direction
Damping ratio (%)
Uncontrolled
Passive control
Active control
0.84
2.5
10.0—11.8
a period of time when wind speed hardly changed before and after the TAD was in
operation. It is clear that within a few waves generated by the TAD, the response
acceleration rapidly decreases.
Fig. 6 shows the time history of the damping ratio during this period of strong
seasonal winds. For estimating the damping ratio, the Random Decrement Technique
[1] is used. The hatched part in the figure shows the functioning time of the TAD. The
damping ratio for the primary vibration mode in direction ½ during the operation
of the TAD becomes approximately 0.8%—12% larger than during its nonoperating period. This nearly corresponds to the free vibration test results. The
damping ratio for the secondary and tertiary mode in direction ½ and direction
X does not change as greatly as that for the primary mode in direction ½. However, it
changes considerably more than during the non-operating period of the TAD.
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K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
Fig. 4. Return period based on daily maximum mean wind speeds.
Table 3 shows the mean value of the damping ratio for each mode during both the
operating and non-operating periods of the TAD.
5.3. Records of strong winds
In this paper, characteristics of the wind speed recorded during the strong seasonal
winds on 23 April 1995 and during Typhoon No. 12 which hit on 17 September 1995
are investigated. A “seasonal wind” is caused by a depression. On the ACT Tower,
a southerly wind with a maximum value of 30.7 m/s mean wind speed was recorded.
Although Typhoon No. 12 was one of the biggest typhoons to hit Japan since the end
of the war, a wind speed of 21.1 m/s as its maximum value for mean wind speed was
recorded. This occurred because the typhoon moved over the Pacific to the south of
the Main Island. Fig. 7 illustrates the time history of the wind speed of both this
seasonal wind and the typhoon. With regard to the seasonal wind, the maximum
instantaneous wind speed reaches the highest value around 13 : 00 when the mean
wind speed becomes highest. As for the typhoon, the maximum instantaneous wind
speed around 12 : 00 when the mean wind speed shows its highest value is almost the
same as that at around 7 : 00. Fig. 8 shows the time history wave of the wind speed.
The seasonal wind during the time indicated in this figure blew from the south and the
typhoon came in from the north—northwest. Furthermore, the wind speed during the
typhoon is indicated for both cases when wind turbulence is small and when it is large.
The turbulence intensity was approximately 15% in case of little turbulence and 40%
at its greatest. Neither periodic nor intermittent components can be obtained from the
wind speed wave in cases where the turbulence of the typhoon is great. Tamura et al.
[2] reported on the case in which turbulence intensity becomes high during typhoons.
K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
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Fig. 5. Time history of response acceleration of seasonal winds.
5.4. Relationship between wind speed and response acceleration (seasonal wind)
Fig. 9 illustrates the relationship between the mean wind speed of the southerly
seasonal wind and the response acceleration. Open symbols in the figure show the
values during the non-operating (OFF) of the TAD and full symbols indicate the
values when it operates (ON). The values marked with L indicate the maximum
response acceleration and h shows the standard deviation of the response acceleration. Furthermore, the response acceleration for the primary, secondary and tertiary
modes, which was computed using a band pass filter for the observed response
acceleration, is also illustrated in the same figure.
Both the maximum response acceleration and the standard deviation of the response acceleration tend to multiply with the increase in mean wind speed. The
acceleration response for the primary vibration mode in direction ½ is fairly low due
to the fact that the TAD operates actively for the vibration control in direction ½. The
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K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
Fig. 6. Time history of the damping ratio of the building for seasonal winds.
Table 3
Damping ratio (%)
X direction
Mode
TAD OFF
TAD ON
Primary
0.88
1.76
½ direction
Secondary
1.02
1.75
Tertiary
1.54
2.14
Primary
0.75
12.1
Secondary
0.82
1.22
Tertiary
1.12
1.3
relationship between the wind speed and the response acceleration in direction ½ is
similar to that for the primary vibration mode due to the fact that the vibration for the
primary vibration mode is predominant in direction ½. It was found from the
response acceleration observed during the strong wind that in direction X the TAD
did not have such great vibration control effects as were seen in direction ½.
¹yphoon. Fig. 10 shows the relationship between the mean wind speed of the
north—northwest wind during the Typhoon and the maximum response acceleration.
In this figure, the response acceleration in direction ½ where the TAD exerts remarkable vibration control effects is shown. There are many variations in the relationship
between the mean wind speed and the response acceleration due to winds with high
K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
Fig. 7. Time history of mean and maximum wind speed.
Fig. 8. Time history of instantaneous wind speed.
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K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
Fig. 9. Relationship of mean wind speed and response acceleration of seasonal winds.
Fig. 10. Relationship of mean wind speed and response acceleration of typhoon.
turbulence intensity. The maximum response acceleration does not rise rapidly with
the increase in mean wind speed, but it rather tends to decrease.
In Fig. 11, the mean wind speed shown in Fig. 10 is replaced by the maximum
instantaneous wind speed. Except for the response acceleration for the tertiary mode,
dispersion of the relationship between the maximum instantaneous wind speed and
the response acceleration becomes small and a tendency in which the maximum
response acceleration multiplies with an increase in maximum instantaneous wind
speed can be seen.
K. Miyashita et al./J. Wind Eng. Ind. Aerodyn. 74–76 (1998) 943– 953
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Fig. 11. Relationship of maximum wind speed and response acceleration of typhoon.
6. Conclusion
As a result of these observations, both the effects of the TAD upon wind-induced
vibration of the Tower and its structural characteristics have been made clear. It
became clear from the results of these observations that when wind turbulence is
heavy as observed during a typhoon, the evaluation of response values of a building
carried out using the maximum instantaneous wind speed is more accurate than that
using the mean wind speed.
Acknowledgements
We would like to express our thanks for the cooperation given for the analyses in
this study by Dr. Hidemoto Mukai and Mr. Kiyoshi Fujinami at the Wind Engineering Institute Co., Ltd.
References
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tower — efficiency of tuned liquid damper, in: Preprints, East European Conf. on Wind Engineering,
Warsaw, Poland, Part 1, vol. 3, pp. 175—184.
[2] Y. Tamura, K. Shimada, K. Hibi, Wind response of Huis Ten Bosch, in: Proc. 12th National Symp. on
Wind Engineering, 1992, pp. 107—118.