DYNAMIC ANALYSIS OF CONCRETE GIRDER BRIDGES UNDER …DYNAMIC ANALYSIS OF CONCRETE GIRDER BRIDGES...
Transcript of DYNAMIC ANALYSIS OF CONCRETE GIRDER BRIDGES UNDER …DYNAMIC ANALYSIS OF CONCRETE GIRDER BRIDGES...
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International Journal of Construction Engineering (IJCE)
Volume 1, Issue 1, January – June 2019, pp. 37-51, Article ID: IJCE_01_01_005
Available online at http://www.iaeme.com/IJCE/issues.asp?JType=IJCE&VType=1&IType=1
© IAEME Publication
DYNAMIC ANALYSIS OF CONCRETE GIRDER BRIDGES
UNDER STRONG EARTHQUAKES: THE EFFECT OF
COLLISION, BASE-ISOLATED PIER AND WING WALL
Desy Setyowulan1, Keizo Yamamoto2, ToshitakaYamao3, Tomohisa Hamamoto4
1Graduate School of Science and Technology, Kumamoto University,
2-39-1 Kurokami, Kumamoto, 860-8555, Japan,
2Department of Civil and Environmental Engineering, Kumamoto University,
2-39-1 Kurokami, Kumamoto, 860-8555, Japan,
3Graduate School of Science and Technology, Kumamoto University,
2-39-1 Kurokami, Kumamoto, 860-8555,
4Department of CivilEngineering, Gunma National College of Technology, 580, Tribamachi,
Maebashi, Gunma 371-8530, Japan,
ABSTRACT
This paper presents the dynamic analysis of concrete girder bridges taking into account the
effect of collision on parapet wall. In addition, adopting of seismic isolation rubber on pier structure
and wing wall on parapet were analyzed. Two spans concrete girder bridgeswith variation of gap
were examined in theoretically by 3D FEM model of ABAQUS. The abutment was simplified by
parapet wall which was modeled by 3D reinforced concrete structure. In order to examine the
seismic behavior of bridge, six different inputs of seismic ground accelerations were applied at
footing of pier structure.It has been suggested that allowing the collisionon abutment by restricting
the girder bridges displacement, the size of expansion joints can be reduced in order to reduce the
cost of construction and seismic reinforcement. According to the analytical results, it was found that
installation of the wing wall had a capability for the horizontal displacement resistance. The seismic
isolation rubber and the wing wall structure had a significant effect in reducing the response stress of
parapet wall on small gap. Furthermore, cracking was also affected by the wing wall.
Keywords:dynamic analysis, collision, gap, isolation rubber, concrete girder bridge, wing wall
I. INTRODUCTION
Before 1995 Kobe earthquake, theconsideration of 10 cm gap has been used in the real bridge
in Japan. However, several damages on bridges occurred, such as collision between adjacent decks
and between deck and abutment. Consequently, collision becomes one of the important aspects to be
evaluated in the seismic performance of the bridge. According to the seismic design by Japanese
Specification of Highway Bridges, it has been determined that necessary gap between the ends of
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two adjacent girders shall be taken in the design of the superstructure for preventing any loss of the
bridge caused by the collision between two adjacent superstructures, a superstructure and an
abutment, or a superstructure and the truncated portion of a pier head, when a bridge is subjected to
Level 2 Earthquake Ground Motion [1]. In the real bridges, gap varied from 20 cm to 50 cm.
However, the adoption of large gap into bridge will increase the construction and seismic
reinforcement cost since relatively large expansion joints have to be used.
Previous study [2] has carried out an investigation on the dynamic behavior of concrete
bridges with consideration of the pounding effect. The damage evaluation of abutment has been
conducted by using 3-dimensional FEM. Pounding has been simulated by setting initial velocity on
superstructure and applying 5 cases of impact velocities. In addition, frame analyses have been
conducted in order to clarify the dynamic behavior of whole bridge by pounding. From this research,
it has been confirmed that severe damage spreads over the entire parapet, the bottom of abutment and
the wing wall abutment in case of impact velocity 3.0 m/s. An effect of large gap on the construction
cost has been studied in another research [3]. The girder and pier have been modeled by beam
elements considering the shock absorber in the end of girder. It has been found that attaching rubber
shock absorber to the end of bridge girder reduce the response stress inthe end of girders and
response rotation angle at the bottom of pier. Moreover, total costs of the proposed seismic
reinforcement are 30% of that current seismic reinforcement.
The behavior of concrete including the model verification of RC beam structures have been
investigated by some researchers using the damage identification by Concrete Damaged Plasticity
model in ABAQUS [4]. This code has shown to be an accurate method in performing nonlinear
behavior of RC structure in comparison with the experimental results [5-8].In addition, elasto-plastic
behaviors in abutments with four different approaches of the wing wall have been analyzed [9].
From this analysis, it has been found that installation of the wing wall had a capability in reducing
the displacement of abutment. Moreover, the initial cracking occurred in the intersection between
parapet wall and abutment wall.
From previous study, it is noted that further study is needed in order to clarify the dynamic
behavior of full bridges due to strong earthquake. However, the adoption of large gap will increase
the size of expansion joint affected the high cost of construction and seismic reinforcement. It has
been suggested that allowing the girder collision at the abutment by restricting the girder bridges
displacement, the size of expansion joints can be reduced in order to reduce the cost of construction
and seismic reinforcement.
This paper presents the dynamic analysis of concrete girder bridges taking into account the
effect of collision on abutment. In addition, adopting of base-isolated pier and wing wall on
abutment were analyzed. Two span concrete girder bridge was examined in theoretically by 3D FEM
model of ABAQUS. Parametric studies on dynamic analyses of bridges were investigated in 5
different gaps. Level 2 of earthquake ground motion was chosen as an input data in order to
investigate its behavior under strong earthquake. Effect of soil pressure during earthquake was not
taken into account. The numerical results represented that the parameters such as response stress,
cracking distribution and displacement were affected by displacement restriction of girder, seismic
isolation rubber and the wing wall. II. NUMERICAL PROCEDURES
2.1 General description of analytical method
The numerical modeling of bridge was conducted by using non-linear FE software,
ABAQUS [4]. Collision phenomenon was simulated by setting 6 different waves of Type 2 input
ground acceleration in X-direction at footing of pier, while the bottom of parapet wall was set to be
hinged (U1=U2=U3=0).
In this research, parametric study of bridges taking into account the effect of the wing wall
and seismic isolation rubber at the bottom of pier were investigated, as shown in Fig. 1 and Fig. 2,
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respectively. The main parameter of this analysis was gap varied from 10, 20, 30, 40, and 50 cm
parallel with Level 2 input of seismic ground accelerations. Two types of loads were applied in
bridge; self-weight as a gravity load of 9.8 m/s2 and the external load from seismic ground
acceleration applied at footing of pier. In this modeling technique, the parapet wall, the reinforcing
bars and the box girder superstructure were idealized by eight-node solid (brick) elements with
reduced integration identified as C3D8R elements and three dimensional truss elements called T3D2
and linear shell elements called S4R.
2.2 Analytical model of bridge
An existing two spans concrete girder bridge adopted from the previous research [3] was
studied. The total length of two span superstructures was 80.0 m with pier (P1) as its center. Parapet
walls were located at both ends, depicted as A1 and A2. The bearing supports were fixed (F) and
movable (M) at Pier 1 and both abutments, respectively. Figs. 3(a) – 3(d) show the dimension and
view of the real bridge.
(a) Side view of the bridge (b) Front view of P1 pier
Figure 2. Model with parapet and wing wall in the first analysis
(a) Concrete element
Figure 1. Model with parapet only in the first analysis
L=12m
H=2.5m
B=0.5m
B=4m
(a) Concrete element (b)Rebar element
(b) Rebar element
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(c) Cross section of superstructure (d) Side view of P1 pier
Figure 3. Dimensions of the bridge (unit: mm)
In all modeling, it was assumed that no liquefaction occurred. Furthermore, constructing of
seismic isolation rubber at bottom of pier structure, called as base-isolated pier, was developed in
order to reduce the seismic response of abutment. The 3-dimensional FE models of bridge are shown
in Figs. 4(a) and 4(b), respectively.
(a) Without wing wall (b) Wing wall
Figure 4. FE-modeling of bridge
2.3 Input seismic waves
Level 2 earthquake ground motions were considered for taking into account in the dynamic
analysis of bridge. Ground type I was chosen as representation of the real soil type, with six input
seismic waves shown in Table 1 and Fig. 5.
Table 1. Acceleration waveform list
Level / Type Earthquake name Nickname Abbreviation
II / I 2003 Tokachi-oki earthquake I – I – 1 L2T1G1-1
Northeastern Pacific Ocean off the coast
earthquake FY 2011
I – I – 2
I – I – 3
L2T1G1-2
L2T1G1-3
II / II Hyogo-ken Nanu Earthquake 1995 II – I – 1
II – I – 2
II – I – 3
L2T2G1-1
L2T2G1-2
L2T2G1-3
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(a) Type I-I-1 wave
(b) Type I-I-2 wave
(c) Type I-I-3
(d) Type II-I-1
(e) Type II-I-2 wave
(f) Type II-I-3 wave
Figure 5. Input JSHB seismic waves Level II earthquake ground motions
2.4 Material properties and material model
Material properties of bridges were shown in Table 2. In this analysis, rebar elements were
treated as elasto-plastic model and concrete of parapet wall was developed by concrete damaged
plasticity (CDP).
Table 2. Material properties of the structure
Material Properties Pier Parapet Wall Bridge
girder Concrete Rebar Concrete Rebar
Young's modulus (GPa) 20.60 206.00 25 200 20.6
Poisson's ratio 0.20 0.30 0.167 0.3 0.20
Density(kg/m3) 2450 7850 2400 7850 2450
Compressive Strength(MPa) 29.40 294.00
(Yield
Stress )
27.5 375.3 29.40
Tensile Strength(MPa) 2.94 3.315 (Yield
stress) 2.94
2.5 Interaction properties and Rayleigh damping
The interacting surfaces between end surface of superstructure and face of parapet wall was
determined as general contact surface algorithm with the friction coefficient of 0.45 and hard contact
for pressure-over closure. Furthermore, an embedded constraint was used to constrain rebar element
into solid element. In the numerical analysis, a damping model of Rayleigh type is used with the
constant damping of 0.02.
2.6 Eigenvalue analysis
The eigenvalue analysis was carried out in order to investigate the effect of seismic isolation
rubber on the natural periods ofthe bridge.The natural periods and the effective mass ratio of each
0 50 100
-400
-200
0
200
400
時間(s)
加速度
(gal
)
0 100 200
-500
0
500
時間(s)
加速度
(gal)
0 100 200
-500
0
500
時間(s)
加速度
(gal)
0 10 20 30
-500
0
500
時間(s)
加速度
(gal)
0 10 20 30
-500
0
500
加速度
(gal)
時間(s)
0 10 20 30
-500
0
500
加速度
(gal)
時間(s)
Ac
c
(ga
l)
Ac
c
(ga
l)
Ac
c
(ga
l)
Ac
c
(ga
l)
Ac
c
(ga
l)
Ac
c
(ga
l)
Time (s)
Time (s) Time (s)
Time (s)
Time (s)
Time (s)
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predominant mode were investigated in order to understand the fundamental dynamic characteristics
of the structure. The maximum effective mass ratios in X, Y and Z directions imply the order of the
predominant natural period.
2.7 Seismic response reduction measurement
In order to improve the seismic performance of structures, the seismic isolation and energy
dissipating systems are frequently used. These techniques are required to reduce the seismic forces
by changing the stiffness and/or damping in the structures, whereas conventional seismic design is
required for an additional strength and ductility to resist seismic forces [10]. In addition, the research
and development works on these devices are being developed extensively.
In this study, one layer and double layer of seismic isolation rubber have been placed at base
of the pier in order to perform the analytical model in reducing the collisionbetween parapet wall and
girder, as shown in Fig. 6. Rubber bearing was modeled by bilinear element in Figure 7 with the
bearing stiffness of K1 and K2were calculated by the following equation.
21 5.6 KK = (1)
e
d
uB
QFK
−=2 (2)
whereF is the maximum shear force (kN), Qdis calculated from the yield load and uBe is effective
design displacement of the seismic isolation bearing (m). The stiffness of seismic isolation rubber
was set to be K1 = 2.27 x 104kN/m2 and K2= 0.35 x 104kN/m2 with Qy = 131.00 kN.
(a) 1 layer (R-1) (b) 2 layer (R-2)
Figure 6. Analytical model of seismic isolation pier Figure 7. Bilinear model
III. RESULTS AND DISCUSSIONS
3.1 Modal analysis
Tables 4 and 5 summarizes the natural frequencies, the natural periods and the effective mass
ratios of each predominant mode of the bridge without seismic isolation rubberand one layer of
seismic isolation rubber (R-0 and R-1 model), then two layer of seismic isolation rubber (R-2),
respectively.
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Table 4. Eigenvalue results for R-0 and R-1 model
Order R-0 model R-1 model
of f (Hz) T (sec)
Effective Mass Ratio (%) f (Hz)
T
(sec)
Effective Mass Ratio (%)
Periods X Y Z X Y Z
1 1.32 0.76 98.14 0.00 0.00 0.45 2.20 99.97 0.00 0.00
2 2.68 0.37 0.20 0.00 0.00 2.90 0.34 0.00 0.00 0.00
3 2.82 0.35 0.00 70.30 12.83 3.03 0.33 0.00 76.54 8.64
4 2.95 0.34 0.00 23.49 40.26 3.19 0.31 0.00 17.24 40.93
5 4.69 0.21 0.00 0.02 38.31 5.02 0.20 0.00 0.02 40.86
6 5.92 0.17 0.00 0.00 0.00 6.30 0.16 0.00 0.00 0.00
7 6.89 0.15 0.00 0.18 0.00 7.48 0.13 0.00 0.32 0.00
8 8.79 0.11 0.00 0.00 0.00 8.36 0.12 0.03 0.00 0.00
9 9.48 0.11 0.00 0.00 0.00 9.13 0.11 0.00 0.00 0.00
10 9.76 0.10 0.00 0.00 2.77 10.36 0.10 0.00 0.00 3.13
11 10.20 0.10 0.83 0.00 0.00 10.61 0.09 0.00 0.00 0.00
12 10.20 0.10 0.83 0.00 0.00 14.09 0.07 0.00 0.00 0.00
13 11.73 0.09 0.00 0.00 0.00 15.66 0.06 0.00 0.48 5.24
14 11.73 0.09 0.00 0.00 0.00 15.78 0.06 0.00 5.31 0.33
15 13.14 0.08 0.00 0.00 0.00 17.95 0.06 0.00 0.02 0.35
Table 5. Eigenvalue results for R-2 model Order R-2 model
of f (Hz) T (sec)
Effective Mass Ratio
(%)
Periods X Y Z
1 0.33 3.00 99.67 0.00 0.00
2 2.90 0.34 0.00 0.00 0.00
3 3.05 0.33 0.00 91.35 0.96
4 3.43 0.29 0.00 2.51 40.32
5 5.25 0.19 0.00 0.01 48.61
6 5.99 0.17 0.33 0.00 0.00
7 6.58 0.15 0.00 0.00 0.00
8 7.49 0.13 0.00 0.31 0.01
9 9.22 0.11 0.00 0.00 0.00
10 10.51 0.10 0.00 0.00 3.80
11 10.56 0.09 0.00 0.00 0.00
12 11.58 0.09 0.00 0.00 0.00
13 14.16 0.07 0.00 0.00 0.00
14 15.74 0.06 0.00 0.66 5.32
15 15.82 0.06 0.00 5.07 0.48
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Figure 7. Predominant mode of R-0 model
Figure 8. Predominant mode of R-1 model
Figure 9. Predominant mode of R-2 model
The predominant Eigen modes deflecting in the longitudinal, vertical and transverse direction
of bridge are shown in Figs. 7-9. According to these figures, it can be seen that seismic isolation
rubber has a capability in reducing the frequency of bridge. R-0 model is possible to vibrate
sympathetically at the 1st mode in longitudinal direction, the 3rd mode in in-plane direction and the
4th mode in transverse direction, similar to R-1 model. However, installing of seismic isolation
rubber in two layers leads the bridge to vibrate sympathetically in transverse direction at the 5th
mode, a slightly changed comparing to other models.
(a) 1st mode (b) 3rd mode (c) 4th mode
(a) 1st mode (b) 3rd mode (c) 4th mode
(a) 1st mode (b) 3rd mode (c) 5th mode
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3.2 Response stress of the parapet wall
Comparison result between the maximum response stressesat base of parapet wall(A1)for
bridge with seismic isolation rubber and wing wall structure as parametric in different input ground
motion are shown in Figs. 10(a)-10(f). R-0, R-1 and R-2 denote as the bridge without, with one layer
and two layers of seismic isolation rubber, respectively. In addition, the response stresses of parapet
wall (A2) are shown in Figs. 11(a)-11(f). W denotes the wing wall which is constructed in both sides
of parapet wall.
From these figures, it can be seen that input ground acceleration of L2T2G1 lead the structure
to vibrate horizontally. It tend to move toward right direction and the maximum response occur in
A2, with the exception of bridge in 10 cm of gap with L2T2G1-2. No collision occurs when the
response stress is zero. Input ground acceleration of L2T1G1-2 and L2T1G1-3 cause the bridge to
vibrate continuously in horizontal direction. Installing of the wing wall reduce the maximum
response stress of parapet wall at a maximum percentage of 65%, as shown in Fig. 11(c). Different
input ground motion lead the different effect on the behavior of parapet wall. As an example is the
input of L2T2G1-1 in bridge with 10 cm of gap, the response stress increase from 6.4 MPa to 39.7
MPa. In general,installing of the wing wall will decrease the response stress of parapet wall. Most of
the results show the tendency of large response stress at the smallest gap of 10 cm, which is possibly
due to increasing number of collision. On the other hand, gap does not give a significant effect on
reducing the response stress in most cases of bridge analyses, as the exception of increasing gap from
10 cm to 20 cm from bridge without seismic isolation rubber.
(a) L2T1G1-1 (b) L2T1G1-2
(c) L2T1G1-3 (d) L2T2G1-1
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(e) L2T2G1-2 (f) L2T2G1-3
Figure 10. Maximum response stress at base of parapet wall in A2
(a) L2T1G1-1 (b) L2T1G1-2
(c) L2T1G1-3 (d) L2T2G1-1
(e) L2T2G1-2 (f) L2T2G1-3
Figure 11. Maximum response stress at base of parapet wall in A1
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In analysis of bridge with one layer and two layers of seismic isolation rubber, the response
stresses due to collision between girder and parapet wall reduced at a range up to 76% at the smallest
gap of 10 cm.Increasing gap from 10 cm to 50 cm raise the maximum response stress of parapet wall
in general.However, in comparison between both layers, two layers seismic isolation rubber does not
give a significant reduction effect on parapet wall. From these results, it was found installing of the
wing wall or seismic isolation rubber on pier is one of an effective way to diminish the response
stress of parapet wall on bridge.
3.3 Horizontal displacement of parapet wall
Fig. 12 shows the maximum horizontal displacement at the top of parapet wall with the input
seismic ground acceleration of L2T2G1. From this figure, it can be seen that the displacement of
parapet wall in A1 positionis smaller than A2 position. Increasing the gap in bridge without seismic
isolation rubber will diminish the displacement of the parapet wall. The displacement behavior of
parapet wall in left and right side without and with consideration of the wing wall are shown in Fig.
13 and Fig. 14. The deformation scale is 10 times the real deformation.
(a) A1 position (b) A2 position
Figure 12. The maximum horizontal displacement at top of parapet wall in L2T1G1-2
(a) A1 position (b) A2 position
Figure 13. Displacement behavior of parapet wall for bridge with L2T1G1-1-R0-10cm
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(a) Left side (b) Right side
Figure 14.Displacement behavior of parapet wall with L2T1G1-3-R0W-10cm
From these figures, it can be described that wing wall part contributes greatly to the
horizontal resistance of abutment against load. During the collision, a large displacement amount
towards the central parapet occurs.
3.4 Cracking distribution of parapet wall
The cracking distribution of parapet wall due to tensile stress for parapet without and with
consideration of the wing wall are shown in Figs. 15-16, respectively. Cracking starts when it has a
positive value, depicted as initial cracking. Then, it propagates up to the maximum value of 0.9. The
area of no cracking and maximum cracking are figured out as “dark blue” regions and “white”
regions, respectively. From these results, it can be explained that cracking propagates from center
part through its width in parapet wall. This propagation leads cracking in edge section between
parapet wall and wing wall.
(a) Initial cracking at 1.15 sec
(b) Final cracking at 30.00 sec
Figure 15. Contour plot of tensile damage in parapet wall for L2T2G1-1-R0-10
(a) Initial cracking at 23.65 sec
(b) Final cracking at 80.00 sec
(c)
Figure 16. Contour plot of tensile damage in parapet wall for L2T1G1-3-R0W-10
No-cracking
Initial cracking Final cracking
No-cracking
Initial cracking Final cracking
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3.5 Effect of gap on number of collision
Effect of the increasing gap to the number of collision between end of girder and parapet wall
in bridge without wing wall are shown in Figs. 17(a)-17(e). Results are compared between response
stress of parapet wall and end of girder. From these figures, it can be described that increasing the
gap will decrease the number of collision. On the other hand, reverse effect occur when installing of
seismic isolation rubber, as shown in Figs. 18(a)-18(e). In addition, seismic isolation rubber causes
the bridge with input of L2T1G1 to sway in one direction with an evidence of increasing number of
stress continuously after the final impact.
(a) Gap 10 cm
(b) Gap 20 cm
(c) Gap 30 cm
(c) Gap 40 cm
(e) Gap 50 cm
Figure 17. Response stress on bridge of L2T1G1-1-R0
50
(a) Gap 10 cm
(b) Gap 20 cm
(c) Gap 30 cm
(c) Gap 40 cm
(d) Gap 50 cm
Figure 18. Response stress on bridge of L2T1G1-1-R1
IV. CONCLUSIONS
The seismic behavior of concrete girder bridges subjected to strong ground motions
considering the effect of collision, base-isolated pier and wing wall were investigated by dynamic
response analysis. Numerical studies were carried out in bridges with the parameters of gap, seismic
isolation rubber and wing wall. Two types of Level 2 seismic ground motions according to JSHB
seismic waves were simulated and discussed. The conclusions of this study are summarized as
following.
1) Installation of the wing wall in parapet had a capability in reducing the maximum response
stress of parapet wall. In addition, it contributed greatly to the horizontal resistance of abutment
against load.
2) Adopting of seismic isolation rubber on pier structure had a great effect on the response
behavior of bridge. In the smallest gap of 10 cm, it diminished the response stress of abutment up to
76%. Generally, increasing the gap was also increase the maximum response stress of parapet wall.
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3) In comparison between installation of one layer and two layers of seismic isolation rubber,
the effect of reducing the response stress due to collision was obtained. However, considering to the
cost of structure, sufficient reduction effect was found in behavior of one layer seismic isolation
rubber.
4) Increasing of gap from 10 to 50 cm in bridge with and without installation of wing wall
decreased the number of collisionon parapet wall. On the other hand, reverse effect occurred in
bridge with seismic isolation rubber.
5) Initial cracking was found at the bottom of parapet wall and spread through the parapet
width. Installation of the wing wall caused cracking at the edges of parapet wall which was
connected to the wing wall.
6) Further study is necessary in order to investigate the effect of soil pressure during earthquake
on the behavior of bridge.
ACKNOWLEDGEMENT
The first author acknowledges DIKTI (Directorate General of Higher Education) in Indonesia
as the financial supporter of the scholarship and University of Brawijaya as the home university.
Their support in completing the doctoral study in Kumamoto University is gratefully appreciated.
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