Study on Improvement of Seismic Performance of ... · The purpose of this study is to improve the seismic performance of steel tower by giving the high damping to the tower. We construct

Journal of Civil Engineering and Architecture 11 (2017) 455-467 doi: 10.17265/1934-7359/2017.05.006

Study on Improvement of Seismic Performance of

Transmission Tower Using Viscous Damper

Masayuki Matsumoto1, Akira Kasai2, Taiji Mazda3, Nobuyuki Ishida4 and Yuki Ito5

1. Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan;

2. Associate Professor, Department of Civil Engineering, Kumamoto University, Kumamoto 860-8555, Japan;

3. Professor, Department of Civil Engineering, Kyushu University, Fukuoka 819-0395, Japan;

4. Japan Steel Tower Co., Ltd., Tokyo 136-0075, Japan;

5. Japan Steel Tower Co., Ltd., Fukuoka 808-0023, Japan

Abstract: The earthquake resistance of transmission tower has been often discussed from the viewpoint of reinforcing the foundation of steel tower, but there are also few studies considering the damping characteristics of the tower. This paper focuses on the viscous damper which has been adopted for seismic reinforcement of bridges in recent years. The purpose of this study is to improve the seismic performance of steel tower by giving the high damping to the tower. We construct a single tower model considering the influence of transmission line, and then simulate the vibration characteristics and seismic behavior of the tower by the eigenvalue analysis and the dynamic response analysis. The results show that the transmission tower with viscous damper can reduce its own response effectively and drastically. This research concludes that it is necessary to consider the extreme increase of steel tower’s response depending on the seismic wave and the collapse of steel tower can be avoided by using the optimum damper in the design of the transmission tower.

Key words: Dynamic analysis, earthquake, response reduction, seismic damper, transmission tower.

1. Introduction

The power supply system is mainly composed by

power plant, power transmission, transformation, and

distribution facilities. It is a necessary condition that

the functions of all these facilities work well together

for stable supply of electric power. Maintaining the

functions of these systems is an extremely important

issue in order to stabilize the power supply that

supports city life.

Currently, the design of power transmission towers

in Japan is mainly based on “Design Standard on

Structures of Transmission (The Institute of Electrical

Engineers of Japan)” (hereinafter referred to as

JEC-127) [1]. When the first Muroto Typhoon hit the

Kansai region in September 1934, and Ise Bay

Typhoon hit the Nagoya region in September 1959 and

Corresponding author: Masayuki Matsumoto, master;

research fields: earthquake engineering, and seismic engineering. E-mail: [email protected].

the Osaka region in September 1961, respectively,

transmission facilities were seriously damaged.

Consequently, these facilities designed by replacing

the wind and snow load as the static load have been

considered to be sufficiently safe for the seismic load.

Because the seismic load may exceed the wind load

only for special structures, JEC-127 has seismic design

based on the seismic intensity method and dynamic

response analysis. The Ji-Ji Earthquake occurred in

September 1999, and the collapses of power

transmission towers were reported in many cases, so

the transmission tower suffered unprecedented damage

by the earthquake. Despite the fact that the design

specification of transmission towers in Taiwan is

slightly severer than that of Japan, many damages of

steel towers have been reported in central Taiwan. That

resulted in extensive damages to Taiwan’s power

supply system. In addition, the 2011 off the Pacific

Coast of Tohoku Earthquake occurred in March 2011,

steel towers close to the Fukushima Daiichi Nuclear

D DAVID PUBLISHING

Study on Improvement of Seismic Performance of Transmission Tower Using Viscous Damper

456

Power Plant collapsed. And that caused serious

damage to steel towers around the Tohoku region.

After the collapse was reported to be caused by tsunami

and slope collapse, the risk of destruction of

transmission tower was reconfirmed again.

Studies [2-4] conducted in the past focused on that

steel towers collapsed, even Taiwan’s design

specification was slightly stricter than that of Japan.

And the importance of seismic performance

evaluation of steel towers was pointed out. In previous

study [5], the effects of ground differential settlement

to seismic performance of transmission towers were

confirmed by using a single tower model. And the

influence of adjacent transmission towers was

clarified in the past study [6]. The previous study [7]

described the development of simplified model for the

transmission tower considering the effects of

transmission lines and viscous dampers. Dynamic

response analysis was conducted by using some types

of models. Differences of dynamic behavior between

each model were compared. In this research, the

evaluation on the earthquake resistance of steel tower

will be examined based on the seismic waves observed

at the Southern Hyogo Prefecture Earthquake (referred

to as the Hyogo Earthquake) and at the 2011 off the

Pacific Coast of Tohoku Earthquake (referred to as the

Tohoku Earthquake). In this paper, we focus on the

viscous damper adopted for seismic reinforcement of

bridges in recent years. Our study will examine to

improve the seismic behavior of steel tower with

viscous damper by giving the high damping.

2. Analysis Model and Conditions

2.1 Target Structure and Analysis Model

In this research, the modeling was carried out based

on the structural data of transmission tower which has

been generally adopted in Japan. The transmission

tower as the target structure was the suspension type of

equal angle steel tower (220 kV), and the structural

diagram of analysis model is shown in Fig. 1. This

model is the steel tower that four legs were equal in

length (the number of nodes is 245, and that of

elements is 672). Here, the characters from A to D in

the figure represent the position of principal members,

and the numbers in the figure represent the panel

number. In addition, assuming the situation which

the same steel towers were arranged continuously and

Fig. 1 Suspended steel tower.

xy

z

AB C D

38.4（

m）

5.7（m）

Transversal

Longitudinal

Vertical

Small number side

Larger number side

12

345

6789

1011

12

13

14

15


457

linearly, the length of span between steel towers was

supposed to be 350 m on both sides. All of principal

members, diagonal members, horizontal members, and

other auxiliary members were modeled as the linear

materials of three dimensional beam elements

(Young’s modulus: 205.9 GPa, Poisson’s ratio: 0.3).

In this model, transmission lines were approximately

modeled by single degree of freedom mass and spring

in each direction. The mass was calculated by the

length of transmission lines based on distance of

adjacent towers. And, the spring constant was

determined from the vibration period of transmission

lines. Regarding the damping of materials as the equal

angle steel, it was known that the value of 1.7% was

obtained when the amplitude was small and the value

of 3.3% to 3.8% when the amplitude was large by the

Sawabe’s vibration test of steel tower. Therefore, in

previous studies, it was assumed to be 2%. Based on

these assumptions, it was set to 2% in this study as

well. Referring to the damping constant of

transmission line, it was concluded that it was 0.4%

from the result of Iwama’s vibration test. The

modeling of transmission line was conducted based on

the previous research. Fig. 2 shows the conceptual

diagram of modeling the transmission lines and the

suspended insulators. The total of two armrests

attaching the ground lines were on the left of tower

top and on the right of tower top, and the rest armrests

were attached to the power line. The mass in the

longitudinal direction was directly attached to each

armband, and the one in the transversal and vertical

direction was attached to each armrest together with

the spring.

2.2 Outline of Analysis Conditions

In the previous research, there were no differences of

responses between the case in which the base of tower

was fixed and the case which was modeled including

the foundation ground. Therefore, in this study, the

foundation was modeled as completely fixed. The

structural analysis program T-DAP III was used as an

analysis software. As the method of eigenvalue

analysis, subspace method was applied. And we

calculated the required degree under the judgment of

Fig. 2 Conceptual figure of modeling transmission line.

mx

mx

mx

mx

mx

mx

mx

mx

mz

mz

mz

mz

mz

mz

mz

mz

my

my

my

my

my

my

my

my


458

effective mass ratio. As the dynamic analysis method,

the direct integration method based on the Newmark β

method (β = 0.25) was applied, and the time interval of

integration was 0.002 s. Furthermore, Rayleigh

damping was defined from the principal modes in

which the effective mass ratio obtained by eigenvalue

analysis was high. The combination of primary natural

frequency and 50 Hz was adopted so that the

combination of the first reference frequency and the

second reference frequency did not show excessive

damping. The input seismic waves were strong motion

records observed at the Hyogo Earthquake and at the

Tohoku Earthquake. And these seismic waves were

input as a single one in the longitudinal direction.

Fig. 3 shows the time history of acceleration.

Based on the method above and the vibration mode

as the result of eigenvalue analysis, four types of

analysis model considering the effect of viscous

dampers were investigated. Figs. 4a-4d show the

models with viscous dampers in each analysis.

Dampers were assembled under the lowest arm

considering deformation of vibration mode of the

tower. Damper used here was velocity dependent type.

Fig. 4e shows the nonlinear model with the -th

power of velocity. The “VL” drawn by the shaded

area in this figure means the limited velocity of elastic

behavior. Eq. (1) shows the characteristics of damping

force in the nonlinear region. The capacity of damping

Fig. 3 Time history of input seismic waves: (a) Jmakobe NS (The Hyogo Earthquake); (b) Tsukidate NS (The Tohoku Earthquake); (c) Hirono (The Tohoku Earthquake).

-1500

-1000

-500

0

500

1000

1500

0 5 10 15 20

Acc

eler

atio

n (

gal)

Time (sec)

JMAKOBE NS------------------------Max = 817.8(gal)

-3000

-2000

-1000

0

1000

2000

3000

0 30 60 90 120 150

Acc

eler

atio

n(g

al)

Time (sec)

TSUKIDATE NS--------------------Max = 2,699.9(gal)

-1500

-1000

-500

0

500

1000

1500

0 30 60 90 120 150

Acc

eler

atio

n(g

al)

Time (sec)

HIRONO NS-----------------------Max = 1,115.9(gal)

(a) JMAKOBE NS (The Hyogo Earthquake)

(b) TSUKIDATE NS (The Tohoku Earthquake)

(c) HIRONO NS (The Tohoku Earthquake)

(a)

(b)

(c)


459

Fig. 4 Analysis model with viscous damper: (a) Model A-1; (b) Model A-2; (c) Model B-1; (d) Model B-2; (e) characteristics of damping force.

force of each damper is 100 kN: ∙ (1)

where: : damping force (kN);

: damping coefficient (kN/(kine)α);

: velocity (kine);

: 0.1

3. Results of Dynamic Response Analysis

Table 1 shows the result of eigenvalue analysis for

model without damper, and Fig. 5 shows the main

mode diagrams of principal vibration in the

longitudinal direction. In addition, Fig. 6 shows the

Fourier amplitude spectrum of response acceleration

at the tower top of principal member A.

Focusing on the peak frequency by the comparison

between Table 1 and Fig. 6, the tower is controlled

only by the primary mode in case of Jmakobe NS,

only the secondary mode is excited in case of

Tsukidate NS, and the vibrations of both modes are

excited in case of Hirono NS. Thus, depending on the

(a) Model A-1 (b) Model A-2

(c) Model B-1 (d) Model B-2

: Damper

h =

15.

5（m）

10

11

12

10

11

12

10

11

12

10

11

12

-VL

VL

Linear

Nonlinear

Nonlinear

-100

-75

-50

-25

0

25

50

75

100

-15 -10 -5 0 5 10 15

Dam

ping

for

ce（kN

）

Velocity （kine）

Damping force Velocity Curve

(e) Characteristics of damping force

(a) (b)

(c) (d)

(e)


460

Table 1 Natural period by eigenvalue analysis (without damper model).

Mode Period (s) Frequency (Hz) Effective mass ratio (%)

Transversal

Line 1st 7.576 0.132 25

Tower 1st 0.505 1.980 30

2nd 0.143 7.000 15

Longitudinal Tower 1st 0.725 1.380 64

2nd 0.187 5.360 24

Vertical Line 1st 7.519 0.133 36

Tower 1st 0.057 17.500 38

Fig. 5 Vibration mode in the longitudinal direction: (a) 1st mode 1,380 Hz; (b) 2nd mode 5,360 Hz.

difference of input seismic wave, the vibration mode

of steel tower differs. When the seismic wave

Jmakobe NS is input, the vibration is controlled only

by the primary mode. This means that the response of

steel tower increases.

Fig. 7 shows the time history of displacement at the

tower top of principal member A in case of model

without damper. Although the maximum values of

input accelerations in cases of Tsukidate NS and

Hirono NS are larger than those of Jmakobe NS, the

maximum value of response displacement of Jmakobe

NS is about three times of the value of Tsukidate NS

and about four times of the value of Hirono NS. These

results can be estimated from the above relationship

between the result of eigenvalue analysis and that of

Fourier amplitude spectrum. This indicates that the

target structure was sensitively affected in case of the

Hyogo Earthquake than in case of the Tohoku

Earthquake.

Figs. 8-10 show the time history of displacement at

the tower top in the model with damper. From the

results of Jmakobe NS, the responses of tower top are

extremely reduced in Model A-1 and Model B-2

comparing with the model without damper. On the

other hand, the reduction effects of response by

dampers are relatively small in Model A-2 and Model

B-1. Furthermore, the early convergence of tower’s

response is recognized in model with damper. This is

one of the features of reduction effect by the viscous

damper. As the results of Tsukidate NS, the responses

are reduced in Model A-1, Model A-2 and Model B-2,

comparing with the model without damper. However,

the reduction effect of response by dampers is

relatively small in Model B-1. About the results of

Hirono NS, the responses are reduced in Model A-1,

Model B-1 and Model B-2, comparing with the model

without damper. The reduction effect by dampers is

small in Model A-2. Referring to the response

displacement of tower top, it is revealed that the effect

of reducing the response is great in Model A-1 and

Model B-2 for seismic waves.

Fig. 11 shows relationship between maximum

(a) 1st mode 1.380Hz (b) 2nd mode 5.360Hz(a) (b)


461

Fig. 6 Fourier amplitude spectrum of response acceleration (without damper model): (a) Jmakobe NS; (b) Tsukidate NS; (c) Hirono NS.

Fig. 7 Time history of tower top displacement (without damper model): (a) Jmakobe NS; (b) Tsukidate NS; (c) Hirono NS.

1.367(Hz)

0

1000

2000

3000

4000

5000

6000

7000

8000

0 1 2 3 4 5 6 7 8 9 10

Four

ier

am

plitu

de s

pect

rum

(gal･s

ec)

Frequency (Hz)

(a) JMAKOBE NS

5.365(Hz)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 1 2 3 4 5 6 7 8 9 10

Four

ier

am

plitu

de s

pect

rum

(gal･s

ec)

Frequency (Hz)

1.385(Hz)

0

1000

2000

3000

4000

5000

6000

0 1 2 3 4 5 6 7 8 9 10

Four

ier

am

plitu

de s

pect

rum

(gal･s

ec)

Frequency (Hz)

(b) TSUKIDATE NS (c) HIRONO NS

-50

-25

0

25

50

0 5 10 15 20

Dis

plac

emen

t (c

m)

Time (sec)

JMAKOBE NS----------------Max = 46.1(cm)

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

TSUKIDATE NS--------------Max = 15.5(cm)

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

HIRONO NS-----------------Max = 12.0(cm)

(a) JMAKOBE NS

(b) TSUKIDATE NS (c) HIRONO NS

(a)

(b) (c)

(a)

(b) (c)


462

Fig. 8 Time history of tower top displacement (with damper model/Jmakobe NS): (a) Model A-1; (b) Model A-2; (c) Model B-1; (d) Model b-2.

Fig. 9 Time history oftowertop displacement (with damper model/Tsukidate NS): (a) Model A-1; (b) Model A-2; (c) Model B-1; (d) Model B-2.

-50

-25

0

25

50

0 5 10 15 20

Dis

plac

emen

t (c

m)

Time (sec)

Model A-1/JMAKOBE NS------Max = 15.9(cm)

Without Damper

With Damper

-50

-25

0

25

50

0 5 10 15 20

Dis

plac

emen

t (c

m)

Time (sec)

Model A-2/JMAKOBE NS------Max = 39.7(cm)

Without Damper

With Damper

-50

-25

0

25

50

0 5 10 15 20

Dis

plac

emen

t (c

m)

Time (sec)

Model B-1/JMAKOBE NS------Max = 29.0(cm)

Without Damper

With Damper

-50

-25

0

25

50

0 5 10 15 20

Dis

plac

emen

t (c

m)

Time (sec)

Model B-2/JMAKOBE NS------Max = 19.0(cm)

Without Damper

With Damper



-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model A-1/TSUKIDATE NS----Max = 11.0(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model A-2/TSUKIDATE NS----Max = 10.3(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model B-1/TSUKIDATE NS----Max = 13.8(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model B-2/TSUKIDATE NS----Max = 11.4(cm)

Without Damper

With Damper



(a) (b)

(c) (d)

(a) (b)

(c) (d)


463

Fig. 10 Time history of towertop displacement (with damper mode/Hiponons): (a) Model A-1; (b) Model A-2; (c) Model B-1; (d) Model B-2.

compression axial force of principal member A and

the height of tower. The red line shows yield axial

force of principal members, and the blue line shows

allowable axial force. Regarding the result of model

without damper, because the steel tower vibrates in

primary mode, the axial force is large at the bottom in

case of Jmakobe NS. Similarly, because the steel

tower is controlled by the secondary mode, the axial

force decreases in the middle part of the tower in case

of Tsukidate NS. Furthermore, in case of Jmakobe NS,

as same as the result of Fig. 8, the axial forces of

principal members are extremely reduced in Model

A-1 and Model B-2, comparing with the case of

model without damper. Axial forces of principal

members in Model A-2 are as the same as the case of

model without damper. The reduction effect of

response by dampers is not recognized in this case. In

case of Tsukidate NS, the response is reduced in all

models, and Model B-2 has the largest reduction in

particular. As the results of Hirono NS, responses of

all models decrease. Especially, Model A-2 which had

a low effect of reducing the response displacement at

the top even shows the reduction effect.

The damping effect is evaluated by changing the

resistive force of viscous damper from reference force

(100 kN) to 50 kN and 150 kN. As the representative

of four models, the result about Model A-1 is notable.

Fig. 12 shows the hysteresis curve of viscus damper

which is relationship between velocity and damping

force for each model in case of Jmakobe NS. Fig. 13

shows the hysteresis curve drawn from the

relationship between displacement and damping force.

The estimated hysteresis curve is obviously drawn. In

the model with resistive force of 100 kN, a solution

diverges when the time interval of integration was

0.002 s, and a stable solution was obtained at the time

interval of 0.0004 s. In the case of 150 kN, that was

obtained when the time interval was 0.000005 s.

Therefore, these models are highly nonlinear.

Table 2 shows the maximum displacement at the

tower top and the reduction rate for each model in the

case of Jmakobe NS. The model with resistive force of

100 kN shows the higher reduction rate than that of

50 kN. The response displacement is reduced even with

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model A-1/HIRONO NS--------Max = 8.3(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model A-2/HIRONO NS-------Max = 11.0(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model B-1/HIRONO NS--------Max = 7.1(cm)

Without Damper

With Damper

-20

-10

0

10

20

0 30 60 90 120 150

Dis

plac

emen

t (c

m)

Time (sec)

Model B-2/HIRONO NS--------Max = 7.2(cm)

Without Damper

With Damper



(a) (b)

(c) (d)


464

Fig. 11 Relationship between maximum axialforce and height of tower: (a) Jmakobe NS; (b) Tsukidate NS; (c) Hirono NS.

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)

Maximum axial force (kN)

JMAKOBE NS

Allowable axial force

Yield axial force

Without Damper

Model A-1

Model A-2

Model B-1

Model B-2

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)


TSUKIDATE NS


Yield axial force

Without Damper

Model A-1

Model A-2

Model B-1

Model B-2

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)


HIRONO NS


Yield axial force

Without Damper

Model A-1

Model A-2

Model B-1

Model B-2

(a) JMAKOBE NS

(b) TSUKIDATE NS

(c) HIRONO NS

(a)

(b)

(c)


465

Fig. 12 Hysteresis curve of viscous damper (relationship berweet velocity and damping force): (a) damping force 50 kN; (b) damping force 100 kN; (c) damping force 150 kN.

Fig. 13 Hysteresis curve of viscous damper (relationship between displacement and damping force): (a) damping force 50 kN; (b) damping force 100 kN;(c) damping force 150 kN.

Table 2 Maximum response displacement and reduction rate in each model.

Model Damping force (kN) Displacement (cm) Reduction rate (%)

Without damper - 46.1 -

Model A-1

50 21.5 53

100 15.9 65

150 17.1 63

Model A-2

50 40.6 12

100 39.7 14

150 41.4 10

Model B-1

50 32.6 29

100 29.0 37

150 26.6 42

Model B-2

50 26.5 43

100 19.0 59

150 19.1 59

-150

-100

-50

0

50

100

150

-30 -20 -10 0 10 20 30

Dam

ping

for

ce(k

N)

Velocity (kine)

-150

-100

-50

0

50

100

150

-30 -20 -10 0 10 20 30

Dam

ping

for

ce(k

N)

Velocity (kine)

-150

-100

-50

0

50

100

150

-30 -20 -10 0 10 20 30

Dam

ping

for

ce(k

N)

Velocity (kine)

(a) Damping force 50kN (b) Damping force 100kN (c) Damping force 150kN

-150

-100

-50

0

50

100

150

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Dam

ping

for

ce(k

N)

Displacement (cm)

-150

-100

-50

0

50

100

150

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Dam

ping

for

ce(k

N)

Displacement (cm)

-150

-100

-50

0

50

100

150

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Dam

ping

for

ce(k

N)

Displacement (cm)(a) Damping force 50kN (b) Damping force 100kN (c) Damping force 150kN

(a) (b) (c)

(b) (a) (c)


466

Fig. 14 Relationship between maximum axialforce and height of towe: (a) Model A-1; (b) Model A-2; (c) Model B-2.

the model of resistive force of 150 kN, but the

reduction rate shows less than or equal to the value of

model with 100 kN. Therefore, when the resistance

force of damper is designed, it is presumed that an

optimum value of the damping force exists around

100 kN.

Fig. 14 shows the relationship of maximum

compression axial force and height of tower for each

model. Although the response is reduced as the

resistance force of the damper increases in all models,

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)


Model A-1


Yield axial force

Without Damper

F=50kN

F=100kN

F=150kN

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)


Model A-2


Yield axial force

Without Damper

F=50kN

F=100kN

F=150kN

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400

Hei

ght

(m)


Model B-2


Yield axial force

Without Damper

F=50kN

F=100kN

F=150kN

(a) Model A-1

(b) Model A-2

(c) Model B-2


467

it is conceivable that an optimum force exists around

100 kN. From the result, the maximum axial force in

the model without damper exceeds the allowable axial

force, it is confirmed that the damping effect is large

particularly in Model A-1 and Model B-2, and it is

relatively small in case of Model A-2.

Comprehensively, as the resistance force of viscous

damper increases, reduction effect of steel tower’s

response tends to be greater.

4. Conclusions

In this study, the tower that was generally adopted in

Japan has been the target structure. The tower used here

was the simplified single tower (220 kV) considering

the effects of transmission lines and viscous dampers.

In the previous paper, it was considered that the

models could accurately simulate the dynamic behavior

of the steel tower during the earthquake. The

differences of dynamic behavior were made clear by

dynamic response analysis using the past earthquake

waves. Especially, the reduction effect of steel tower’s

response with dampers was clarified. As the result, the

viscous dampers of velocity dependent type can reduce

the response of steel tower effectively and drastically.

The main results from this study are listed as follows:

(1) As the result of dynamic analysis using the

seismic waves at the Hyogo Earthquake and at the

Tohoku Earthquake, the response especially at the

tower top in the case of the Hyogo Earthquake was

extremely large;

(2) From the study of models with different setting

conditions of viscous damper, it became clear that it is

possible to reduce the response displacement at the top

by the dampers;

(3) As the result of evaluating the maximum axial

force of principal members, it was confirmed that the

model with low effect of response reduction also

definitely showed the reduction effect;

(4) There was an optimum resistance force of the

viscous damper for each target structure, and the great

reduction effect of tower’s response could be

obtained by optimally designing the performance of

dampers.

Acknowledgments

We thank the National Research Institute for Earth

Science and Disaster Resilience (NIED) for providing

us with the strong motion records of K-NET.

References

[1] The Institute of Electrical Engineers of Japan, Electrical Standards Committee. 1979. Design Standard on Structures of Transmission (JEC-127-1979), Denkishoin.

[2] Japan Society of Civil Engineers. 1999. The 1999 Ji-Ji Earthquake, Taiwan—Investigation into Damage to Civil Engineering Structures.

[3] Mazda, T., Otsuka, H., Uchida, H., and Ikeda, S. 2001. “A Study on Earthquake Responses of Steel Tower with Additional Damping.” ASME PVP 428-2: 43-8.

[4] Mazda, T., Otsuka, H., Ikeda, S., and Uno, K. 2004. “A

Study on Damage of Transmission Steel Tower with

Unequal Legs in the Chi-Chi Earthquake Taiwan.” In

Proceedings of 13th World Conference of Earthquake

Engineering, Vol. DVD No.739.

[5] Mazda, T., Matsumoto, M., Oka, N., and Ishida, N. 2010.

“Evaluation of the Seismic Behavior of Steel Transmission

Towers with Different Boundary Conditions.” In

Proceedings of the Tenth International Conference on

Computational Structures Technology, Paper.329.

[6] Mazda, T., Kandemir, E. C., Matsumoto, M., Oka, N., and

Ishida, N. 2011. “Evaluation of the Dynamic Behavior of a

Standard Power Transmission Steel Tower in Japan during

an Earthquake.” In Proceedings of the Thirteenth

International Conference on Civil, Structural and

Environmental Engineering Computing, Paper.47.

[7] Mazda, T., and Matsumoto, M. 2015. “Evaluation on

Seismic Performance of Transmission Steel Tower with

Viscous Dampers.” In Proceedings of 9th Asia Pacific

Structural Engineering and Construction Conference,

396-401.

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Study on Improvement of Seismic Performance of ... · The purpose of this study is to improve the seismic performance of steel tower by giving the high damping to the tower. We construct