effect of damper on seismic response of cable …...long-span bridge. cable bridges are divided into...
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International Journal of Civil Engineering and Technology (IJCIET)
Volume 9, Issue 2, February 2018, pp. 326–339, Article ID: IJCIET_09_02_032
Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=2
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication Scopus Indexed
EFFECT OF DAMPER ON SEISMIC RESPONSE
OF CABLE-STAYED BRIDGE USING ENERGY-
BASED METHOD
Fereidoun Amini
Professor, Department of Civil Engineering,
Iran University of Science & Technology, Tehran, Iran
Solmaz Sadoughi Shabestari, Mohammad Emamian
M.Sc., Department of Civil Engineering,
Iran University of Science & Technology, Tehran, Iran
ABSTRACT
Bridges are a vital element of transportation networks. As any disorder in the
maintenance or utilization of bridges may cause irrecoverable incidents, the
vulnerability of bridges to earthquakes must be seriously considered. Dampers are
extensively used in the handling of earthquake forces; however, their optimization and
optimal location have not been clarified. Considering the unjustified use of force-
displacement design methods in the seismic design of important structures, such as
bridges, the use of an energy-based approach with nonlinearly behaving materials
and the concept of hysteretic energy are more rational and practical. Therefore, in
this study, the effect of dampers and their location on the seismic response of cable-
stayed bridges is investigated by an energy-based method. For this purpose, a case
study is examined via a numerical study. The results indicate that, to reduce the
bridge’s seismic response to earthquake forces, a damper installed between the deck
and pylon is more effective than a damper installed on the cables.
Key words: Control of structure, Cable-stayed Bridge, Damper, Energy-based
method.
Cite this Article: Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad
Emamian, Effect of Damper on Seismic Response of Cable-Stayed Bridge Using
Energy-Based Method. International Journal of Civil Engineering and Technology,
9(2), 2018, pp. 326-339.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=9&IType=2
1. INTRODUCTION
Typically, long span bridges connect important points within transportation systems, and it is
crucial for that connection to be maintained after an earthquake. Therefore, their seismic
performance should be acceptable. Cable bridges are one of the most common structural
systems for long span bridges. For spans over 200 m, cable bridges are very suitable and
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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should be considered as one of the main options when selecting the structural system of a
long-span bridge. Cable bridges are divided into two types: cable-stayed bridges and
suspension bridges [1].
Figure 1 Cable-Supported Bridges: a) cable-stayed bridge; b) suspension bridge
Designers are always investigating safe bridge designs and the retrofitting of existing
bridges against earthquakes. Thus, various methods have been utilized to achieve these
objectives. The most efficient approach consists of using various structural control systems.
Generally, structural control is performed by using tools or members in the structure to
control its behavior against lateral forces. In recent decades, the seismic control of structures
has drawn considerable attention from engineers.
During strong earthquakes, structures usually exceed their elastic limit. Therefore, the
design methods that have been used in recent decades, including force-based methods, do not
provide complete information on the nonlinear behavior of structures during an earthquake.
These methods usually result in forces that need to be considered. Hence, these forces are not
optimal; therefore, the design of a bridge with consideration to these forces is not optimized
and does not ensure an acceptable structural performance during an earthquake.
Plastic deformation should be considered when estimating earthquake damage or when
determining the required maximum response. Regarding the nature of the earthquake force,
the structure, or any member of the structure, is subjected to several opposite forces and
different time-dependent deformations. This can be investigated by considering the energy
absorbed into the structure.
Thus, the use of energy-based methods by incorporating the nonlinear behavior of the
structure and the hysterical energy concept is a good alternative to methods based on force
and displacement. The objective of developing the design of a bridge by employing energy
based-methods is to minimize the response and hysteretic energy absorbed by the structural
members. Thereby, the seismic response of the structure is improved.
The energy-based method was first proposed by Housner in 1956 [2]. In his method, the
energy absorption capacity of the structure against large earthquakes was introduced as a
structural evaluation parameter, and the equivalent velocity was defined as an indicator of
absorbed energy. Therefore, Housner used this velocity as an approximation to the structure’s
nonlinear behavior demand. Uang and Bertero were among the pioneers of the energy
method. In 1990, they conducted a parametric study on the energy method [3] and obtained
the main parameters and their effectiveness on energy. Finally, they defined two types of
equilibrium equations for energy: one for absolute energy and another for relative energy. As
Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad Emamian
http://www.iaeme.com/IJCIET/index.asp 328 [email protected]
𝐸𝐼 = 𝐸𝑘 + 𝐸𝜉 + 𝐸𝑆 +
𝐸𝐻
they pointed out in their report, the absolute energy was more physically meaningful in
comparison to relative energy. Additionally, for structures with low and high periods, the
calculations of the input energy were different in absolute and relative terms. In 1994, Fajfar
and Vidic studied the input energy, the residual energy spectra, and their ratio [4]. In 2001,
Riddell and Garcia, conducted a study on the nonlinear response of single-degree-of-freedom
systems (SDOFs) under earthquake excitation. They concluded that by using the amount of
energy absorbed through nonlinear deformations, the deformation capacity required to carry
out an appropriate design could be achieved [5]. In 2002, Leelataviwat et al. used the concept
of energy balance to calculate the design forces for an SDOF structure. Later they expanded
the application of the concept to a multi-degree-of-freedom structure [6]. In 2003, Chou and
Uang suggested the use of energy as a substitute for force and displacement responses.
Accordingly, they used energy as an indicator of time-dependent structural damage [7]. Since
then, the energy-based method has been extensively applied to seismic design and analysis.
For instance, in 2010, based on the energy-based method and by considering the flexural
rigidity and sag-extensibility of the cable, Cheng et al., investigated the damping properties of
a cable-damper system [8]. In 2013, Habibi et al. proposed a stepwise multi-mode energy-
based design method for seismic retrofitting with passive energy dissipation systems as an
alternative to strength and displacement-based methods [9].
In this study, the effect of the damper and its location on the reduction of the cable-stayed
bridge’s responses to earthquakes was investigated using an energy-based method and
considering the hysterical energy concept. Through a case study, the analysis, modeling, and
structural responses against earthquake were evaluated with and without dampers. The
obtained results and their interpretation are presented in this paper.
2. BRIEF REVIEW OF ENERGY-BASED METHOD EQUATIONS
In the same way as in other methods, the design carried out in this study was based on the
following equation:
(1)
By considering the dynamic equilibrium equation of an SDOF system, and by integrating
it with the displacement occurring during an earthquake, the structural capacity and demand
for SDOFs could be defined within an absolute and relative state.
2.1. Absolute State
In this case, the general energy relationship is expressed follows:
(2)
where is the absolute kinetic energy, is the damping energy, is the absorbed
energy, is the elastic strain energy, is the energy dissipated by the hysteretic or plastic
deformation, and is the absolute input energy. These parameters were obtained from the
following equations:
(3)
∫ = ∫
Demand > Capacity
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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∫ = +
∫
where c is the damping coefficient, m is the mass of the system, is the absolute
displacement of the system, ν is the relative displacement of the system, is the ground
displacement, and is the force stored in the system. With respect to Equations (1) and (2),
the left side of Equation (2) can be assumed equivalent to the structural demand, while its
right side is equal to the structural capacity.
2.2. Relative State
In this case, the general energy relationship is as follows:
(4)
where is the relative kinetic energy and
is the relative input energy, which can be
obtained as follows:
(5)
∫
In this case, with respect to Equations (1) and (4), the left side of Equation (4) can be
assumed equivalent to the structural demand, while its right side is equal to the structural
capacity.
3. MODELING
In this paper, a case study was carried out to investigate the effect of dampers on the reduction
of structural responses to earthquakes. Thus, the Vasco da Gama cable-stayed bridge in
Lisbon, Portugal, which has been presented by Pedro and Reis in 2010 [10], was modeled. In
2016, Maleki and Shabestari, modeled this bridge and investigated its response modification
factor [11]. In the present work, their model was modified and considered as a case study. The
bridge was modeled using the CSI Bridge 2017 software, which is developed by Computers
and Structures, Inc.
Figure 2 Vasco da Gama cable-stayed bridge in Lisbon, Portugal
𝐸𝐼 = 𝐸𝑘
+ 𝐸𝜉 + 𝐸𝑆 +
𝐸𝐻
Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad Emamian
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Figure 3 Perspective of bridge model
In this study, the Vasco da Gama cable-stayed bridge was modeled with applied loading
under three different conditions, as follows:
Without damper
With dampers on the bridge cables
With dampers between the deck and pylons
3.1. Model A: Cable-Stayed Bridge without Damper
3.1.1. Modeling specifications and assumptions
As can be seen in Fig. 4, the bridge has three spans. The length of the main span is 300 m,
while the length of the two side spans is 120 m.
Figure 4 Longitudinal geometry of bridge
The structural system of the deck consists of a slab and girder system. The width of the
bridge deck is 22 m. The deck was modeled via single frame modeling. Considering that most
of the seismic behavior of cable-stayed bridges is related to pylon behavior rather than to deck
behavior, a deck model with a single frame was considered appropriate. As shown in Fig. 5,
the pylons in this bridge are H-shaped and have a height of 135 m. The pylons were modeled
by using frame elements. At the level of the deck, each pylon is connected to the deck by a
main transverse beam.
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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Figure 5 Elevation view of H-shaped pylon
In this bridge, a semi-fan cable arrangement system is used, and there are 56 cables
attached to each pylon in the two planes on the left and right sides of the deck, respectively. In
the main span, the spacing of the cables is 10 m, while the side span spacing is 8 m. The
cables were modeled by frame elements, and their section was defined such that it represented
a 30-strand cable. By modeling the cables in this way, their flexural stiffness could be
considered. The geometric nonlinear behavior of the cables was captured by large
displacement analysis. The labels of the cables in the model are presented in Fig. 6.
Figure 6 Cable labels in the model
Additionally, due to the fact of the deck being modeled by a single element, and of the
cables being located on both sides of the deck, rigid elements were used to make cables with
an exact angle. These elements were modeled by link elements and defined as rigid elements.
To capture the nonlinear behavior of the structure, many nonlinear concentrated hinges
were defined as fiber hinges. These hinges consider the nonlinear behavior of elements in the
combination of axial forces and flexural moments simultaneously. To define these hinges, the
sections of the elements were divided into many smaller elements.
𝑏 → 𝑏 4 𝑐 4 → 𝑐 𝑐 → 𝑐 4 𝑏 4 → 𝑏
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3.1.2. Loading Specifications
In this model, various loads were applied to the bridge. The most important applied load was
the dead load due to the weight of the constituent elements. The live load was defined based
on the AASHTO specifications and with an impact factor of 1.3. The earthquake loads were
assigned to the bridge according to the AASHTO specifications and with consideration to the
non-urban bridge guidelines [12].
After developing a complete model of the structure and its loading, nonlinear time history
analysis was used with consideration to the P-delta and large displacement effects. For each
time history analysis, three datasets were assigned in each direction. The Northridge, El
Centro, and San Fernando records were used as the time history datasets matching the design
spectrum. Respectively, these three earthquake records were considered as Fema 1-1, Fema 6-
1, and Fema 21-1, as shown in Fig. 7.
a b c
Fem
a
1-1
Fem
a
6-1
Fem
a
21-1
Figure 7 Time history of Fema 1-1, Fema 6-1, and Fema 21-1. a) 1 dir; b) 2 dir; 3) up dir
3.1.3. Cable Forces
In cable-stayed bridges, the vertical displacement of the deck due to the dead load should be
very small, and the bridge should have a predetermined longitudinal profile. Therefore, the
-0.4
-0.2
0
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tive
acc
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g)
time (sec) -1
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tive
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g)
time (sec)
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time (sec)
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time (sec)
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time (sec)
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time (sec)
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time (sec)
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time (sec)
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-0.1
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0 10 20 30rele
tive
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n (
g)
time (sec)
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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cable tension on these bridges was determined accordingly. Thus, the deck of the bridge was
modeled as a beam, whose supports were rollers aligned with the cables. Then, the dead loads
were applied to the beam and the forces of the cables were obtained by analyzing the beam.
The basic specifications of the cables were considered based on these forces. Subsequently,
by using a trial and error process, the cable forces changed until the deflection profile under
the dead loads was close enough to the predetermined desired state. The results of this trial
and error process are presented in Tables 1 and 2.
Table 1 Force and deck displacement in cables b1 to b14
Table 2 Force and deck displacement in cables c1 to c14
3.2. Model B: Cable-Stayed Bridge with Damper Installed on Cables
Under this condition, a nonlinear damper with a stiffness of 100,000
and a damping factor
of 15.13
was attached to each cable. Each damper was connected to the deck on one
side, and to the cable on the other side. The location of the damper on the cable was at a
distance equal to 0.06 of the cable length before the damper was attached. Time history
analysis was also conducted under this condition.
cable name cable force in deck level (ton) displacement of deck level (mm)
b1 175.38 -2.17
b2 172.4 -3.57
b3 168.86 -4.26
b4 164.8 -4.34
b5 160.25 -3.97
b6 155.31 -3.3
b7 150.1 -2.55
b8 144.77 -1.94
b9 139.54 -1.74
b10 134.79 -2.2
b11 131.12 -3.57
b12 129.42 -5.92
b13 130.65 -8.95
b14 134.57 -11.68
cable name cable force in deck level (ton) displacement of deck level (mm)
c1 180.89 -4.85
c2 180.88 1.24
c3 181.39 5.4
c4 183.12 5.68
c5 112.87 2.9
c6 115.5 0.98
c7 117.17 1.73
c8 117.26 5.12
c9 115.62 9.94
c10 112.58 14.35
c11 109.22 16.4
c12 107.64 14.47
c13 111.18 7.87
c14 122.83 -2.36
Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad Emamian
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3.3. Model C: Cable-Stayed Bridge with Damper between Deck and Pylons
Under this condition, a nonlinear viscous damper, with a stiffness of 500,000
, damping
coefficient of 2,000
, and equal to 0.5, was placed at the transverse beam location
between the deck and pylons. Time history analysis was also conducted under this condition.
4. RESULTS AND FIGURES
The diagrams showing the performance of each model are presented according to the results
obtained by the nonlinear time history analysis of the three described structural models.
First, the damper’s energy was investigated as a parameter in the evaluation of its
performance. The diagrams below show the energy of the utilized damper in the modeling
carried out with regard to each of the three earthquake records. As can be seen in the
diagrams, the energy of the dampers in model B is negligible in comparison to the energy in
model C. This suggests that these dampers are not efficient and that their placement in the
structure does not affect the structure's response. Therefore, the different structural responses
were compared under the conditions of A and C, as shown in Figures 9, 10, and 11.
Figure 8 Damper energy in Models B and C. a) Fema 1-1; b) Fema 6-1; c) Fema 21-1
……
-1.0E+06
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
0 10 20 30 40
dam
per
en
ergy
(J)
time (sec)
Model b
Model c
-1.0E+060.0E+001.0E+062.0E+063.0E+064.0E+065.0E+066.0E+06
0 10 20 30
dam
per
en
ergy
(J)
time (sec)
Model b
Model c
-5.0E+06
0.0E+00
5.0E+06
1.0E+07
1.5E+07
0 10 20 30
dam
per
en
ergy
(J)
time (sec)
Model b
Model c
0.0E+00
2.0E+06
4.0E+06
6.0E+06
8.0E+06
1.0E+07
1.2E+07
1.4E+07
0 20
inp
ut
ener
gy (
J)
time (sec)
Model a
Model c
0.0E+00
2.0E+05
4.0E+05
6.0E+05
8.0E+05
1.0E+06
1.2E+06
1.4E+06
1.6E+06
0 20
hys
tere
tic
ener
gy (
J)
time (sec)
Model a
Model c
b
a
c
b
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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Figure 9 Results of nonlinear time history Fema 1-1 analysis for three described structural models. a)
Time history of input energy; b) time history of hysteretic energy; c) time history of kinetic energy; d)
time history of base shear; e) time history of base moment; f) time history longitudinal displacement at
mid-span; g) time history vertical displacement at mid-span; ( Cable-stayed bridge without damper,
Cable-stayed bridge with cable damper, Cable-stayed bridge with damper between deck and pylon)
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
0 10 20 30
kin
etic
en
ergy
(J)
time (sec)
Model a
Model c
c
-1.5E+07
-1.0E+07
-5.0E+06
0.0E+00
5.0E+06
1.0E+07
1.5E+07
0 20
bas
e sh
ear
(N)
time (sec)
Model a
Model c
d
-8.0E+10
-7.5E+10
-7.0E+10
-6.5E+10
-6.0E+10
-5.5E+10
-5.0E+10
-4.5E+10
0 20
bas
e m
om
ent
(N-m
)
time (sec)
Model a
Model c
e
-0.15
-0.1
-0.05
0
0.05
0.1
0 10 20 30Lon
gitu
din
al d
isp
lace
men
t in
th
e
mid
dle
of
the
span
(m
) time (sec)
Model a
Model c
f
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0 10 20 30vert
ical
dis
pla
cem
ent
in t
he
m
idd
le o
f th
e sp
an (
m)
time (sec)
Model a
Model c
g
0.0E+00
2.0E+06
4.0E+06
6.0E+06
8.0E+06
1.0E+07
1.2E+07
0 10 20 30
inp
ut
ener
gy (
J)
time (sec)
Model a
Model c
a
0.0E+00
2.0E+05
4.0E+05
6.0E+05
8.0E+05
0 10 20 30
hys
tere
tic
ener
gy (
J)
time (sec)
Model a
Model c
b
Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad Emamian
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Figure 10 Results of nonlinear time history Fema 6-1 analysis for three described structural models. a)
Time history of input energy; b) time history of hysteretic energy; c) time history of kinetic energy; d)
time history of base shear; e) time history of base moment; f) time history longitudinal displacement at
mid-span; g) time history of vertical displacement at mid-span; ( Cable-stayed bridge without damper,
Cable-stayed bridge with cable damper, Cable-stayed bridge with damper between deck and pylon)
0.0E+00
5.0E+05
1.0E+06
1.5E+06
2.0E+06
2.5E+06
3.0E+06
0 10 20 30
kin
etic
en
ergy
(J)
time (sec)
Model a
Model c
c
-1.5E+07
-1.0E+07
-5.0E+06
0.0E+00
5.0E+06
1.0E+07
1.5E+07
0 10 20 30bas
e sh
ear
(N)
time (sec)
Model a
Model c
d
-7.5E+10
-7.0E+10
-6.5E+10
-6.0E+10
-5.5E+10
-5.0E+10
0 10 20 30
bas
e m
om
ent
(N-m
)
time (sec)
Model a
Model c
e
-3.0E-01
-2.0E-01
-1.0E-01
0.0E+00
1.0E-01
2.0E-01
3.0E-01
0 10 20 30Lon
gitu
din
al d
isp
lace
men
t in
th
e
mid
dle
of
the
span
(m
) time (sec)
Model a
Model c
f
-0.1
-0.05
0
0.05
0.1
0 10 20 30
vert
ical
dis
pla
cem
ent
in t
he
m
idd
le o
f th
e sp
an (
m)
time (sec)
Model a
Model c
g
0.0E+00
5.0E+06
1.0E+07
1.5E+07
2.0E+07
2.5E+07
0 10 20 30
inp
ut
ener
gy (
J)
time (sec)
Model a
Model c
a
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
6.0E+06
0 10 20 30
hys
tere
tic
ener
gy (
J)
time (sec)
Modela
b
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
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Figure 11 Results of nonlinear time history Fema 21-1 analysis for three described structural models.
a) Time history of input energy; b) time history of hysteretic energy; c) time history of kinetic energy;
d) time history of base shear; e) time history of base moment; f) time history longitudinal displacement
at mid-span; g) time history vertical displacement at mid-span; ( Cable-stayed bridge without
damper, Cable-stayed bridge with cable damper, Cable-stayed bridge with damper between deck
and pylon)
Moreover, in Table 3, the maximum values for each structural response in Models A and
C are presented for Fema 1-1.
Table 3 Maximum structural response values in Models A and C for Fema 1-1
Model A Model C
Input energy (J) 1.19E+07 1.21E+07
Link hysteretic energy (J) 1.49E+06 9.10E+05
Kinematic energy (J) 4.46E+06 4.55E+06
Base shear (N) 1.21E+07 8.73E+06
Base moment (N-m) -5.35E+10 -5.37E+10
Longitudinal displacement (m) 8.21E-02 8.79E-02
Vertical displacement (m) 9.99E-02 5.62E-02
Damper energy (J) 0.00E+00 4.22E+06
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
6.0E+06
0 10 20 30
kin
etic
en
ergy
(J)
time (sec)
Model a
Model c
c
-3.0E+07
-2.0E+07
-1.0E+07
0.0E+00
1.0E+07
2.0E+07
3.0E+07
0 10 20 30
bas
e sh
ear
(N)
time (sec)
Model a
Model c
d
-7.5E+10
-7.0E+10
-6.5E+10
-6.0E+10
-5.5E+10
-5.0E+10
0 10 20 30
bas
e m
om
ent
(N-m
)
time (sec)
Model a
Model c
e
-4.0E-01-3.0E-01-2.0E-01-1.0E-010.0E+001.0E-012.0E-013.0E-014.0E-01
0 20Lon
gitu
din
al d
isp
lace
men
t in
th
e
mid
dle
of
the
span
(m
) time (sec)
Model a
Model c
f
-0.2
-0.1
0
0.1
0.2
0 10 20 30
vert
ical
dis
pla
cem
ent
in t
he
m
idd
le o
f th
e sp
an (
m)
time (sec)
Model a
Model c
g
Fereidoun Amini, Solmaz Sadoughi Shabestari, Mohammad Emamian
http://www.iaeme.com/IJCIET/index.asp 338 [email protected]
Based on Equation 2, the input energy was equal to the sum of the strain, kinetic,
damping, and hysteretic energy. Therefore, according to the Energy Conservation Law, as the
energy dissipated by the dampers increased, the structural responses, such as the
displacement, velocity, and acceleration, were reduced as a consequence of the decreasing
strain and kinetic energy. Additionally, at a certain seismic level, the lost hysteresis energy owing to the nonlinear behavior of members, such as the formation of plastic hinges, was
reduced. Therefore, the structural damage caused by the earthquake was also reduced.
In the diagrams presented above, it can be seen that by adding a damper between the
pylon and deck, the maximum hysterical and kinetic energy values of the structure decreased
by approximately 35% and 5%, respectively. The maximum base shear value at the end of the
pylon was reduced by approximately 25%. Moreover, the time until the occurrence of the
maximum values was decreased, and the maximum longitudinal and transverse displacement
values at mid-span were reduced by approximately 7% and 40%, respectively.
5. CONCLUSIONS
In this study, the effects of dampers on the responses of a cable-stayed bridge to earthquake
were investigated using an energy-based method. Specifically, a case study was carried out
regarding the effect exerted by dampers placed on the cables and the effect exerted by
dampers placed between the pylons and deck on the structural responses to the recorded
Northridge, El Centro, and San Fernando earthquakes. The numerical modeling results
indicated that the dampers on the cables did not have any effect on the bridge’s structural
responses to earthquakes. However, the damper between the pylon and deck reduced the
structural responses considerably, including the hysterical energy, base shear, and vertical
displacement responses. It was also shown that a large portion of the seismic force acting on
the bridge was related to the weight of the pylons. For further investigations on the
performance improvement of cable-stayed bridges, it is suggested that consideration be given
to the behavior of the pylons and control systems.
REFERENCES
[1] Svensson, H. Cable-stayed bridges: 40 years of experience worldwide. 2013: John Wiley
& Sons.
[2] Housner, G. W. Limit design of structures to resist earthquake. in Proc. of 1st WCEE.
1956.
[3] Uang, C. M. and Bertero, V. V. Evaluation of seismic energy in structures. Earthquake
Engineering & Structural Dynamics, 1990, 19(1), pp. 77-90.
[4] Fajfar, P. and Vidic, T. Consistent inelastic design spectra: hysteretic and input energy.
Earthquake Engineering & Structural Dynamics, 1994, 23(5), pp. 523-537.
[5] Riddell, R. and Garcia, J. E. Hysteretic energy spectrum and damage control. Earthquake
Engineering & Structural Dynamics, 2001, 30(12), pp. 1791-1816.
[6] Leelataviwat, S., Goel S. C., and Stojadinović, B. Energy-based seismic design of
structures using yield mechanism and target drift. Journal of Structural Engineering,
2002, 128(8), pp. 1046-1054.
[7] Chou, C. C. and Uang, C. M. A procedure for evaluating seismic energy demand of
framed structures. Earthquake Engineering & Structural Dynamics, 2003, 32(2), pp. 229-
244.
Effect of Damper on Seismic Response of Cable-Stayed Bridge Using Energy-Based Method
http://www.iaeme.com/IJCIET/index.asp 339 [email protected]
[8] Cheng, S., Darivandi, N. and Ghrib, F. The design of an optimal viscous damper for a
bridge stay cable using energy-based approach. Journal of Sound and Vibration, 2010,
329(22), pp. 4689-4704.
[9] Habibi, A., Chan, R. W. and Albermani, F. Energy-based design method for seismic
retrofitting with passive energy dissipation systems. Engineering Structures, 2013, 46, pp.
77-86.
[10] Pedro, J. J. O. and Reis, A. J. Nonlinear analysis of composite steel–concrete cable-stayed
bridges. Engineering structures, 2010, 32(9), pp. 2702-2716.
[11] Maleki, S. and Shabestari, A. S., Evaluation of Response Modification Factor for Cable-
Stayed Bridges. 2016.
[12] AASHTO LRFD bridge design specifications. 2014, Washington DC: American
Association of State Highway Transportation Officials.
[13] J.Premalatha, R.Manju and V.Senthilkumar, Seismic Response of Multistoreyed Steel
Frame with Viscous Fluid – Scissor Jack Dampers, Journal of Civil Engineering and
Technology, 8(8), 2017, pp. 289–312
[14] Y. Naga Satyesh and K. Shyam Chamberlin, Seismic Response of Plane Frames with
Effect of Bay Spacing and Number of Stories Considering Soil-Structure Interaction.
International Journal of Civil Engineering and Technology, 8(1), 2017, pp. 628– 638.