International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 10 (2016) pp 6890-6896
© Research India Publications. http://www.ripublication.com
6890
A Numerical Study on the Seismic Behavior of Composite Steel Plate Shear
Walls with Openings
Soheil Kordbegli1 and Farhang Farahbod2* 1MSc in civil engineering structures, Department of Civil Engineering,
West Tehran Branch, Islamic Azad University, Tehran, Iran. 2PhD, Faculty Member, Department of Civil Engineering,
West Tehran Branch, Islamic Azad University, Tehran, Iran. corresponding author
Abstract
In recent years the use of composite steel plate shear walls, as
a lateral load resisting system, has been increasing. In this
paper our aim is to study the seismic behavior of these
composite shear walls with embedded openings by
introducing the size and position of openings as the variables
of the study. Numerical studies were carried out to evaluate
the effect of elastic stiffness, effective or secant stiffness,
failure load, absorbed energy, and ductility ratio on the
performance of these walls. The results of analysis of finite
element models in the wall with openings modeled in
ABAQUS software showed that the use of openings in the
center of these walls was favorable due to the reducing
negative effects of the studied parameters on the wall
performance, and their use in the corners of the composite
shear walls is not suggested. Major changes and value
reduction rate of the parameters in different areas were seen in
the openings wider than 1000 mm. We concluded that
embedding openings in the corners of the composite steel
plate shear walls, especially those with larger sizes should be
avoided.
Keywords: Composite steel plate shear walls, Seismic
behavior, Stiffness, Ductility, Numerical study
Notations
Fy Specified minimum yield stress of the plate
Fu Specified minimum tensile strength
µ Ductility coefficient
D Ductility ratio
E Modulus of elasticity
E Absorbed energy
Ke Elastic stiffness
Pu Failure load
Keff Effective or secant stiffness
𝑃𝑝𝑒𝑎𝑘 Maximum absolute value of load resisted by the wall
∆e Displacement at 0.4𝑃𝑝𝑒𝑎𝑘
Δu Ultimate displacement
Δyield Yield Displacement
INTRODUCTION
From the beginning of the study and design of building
structures, one of the main concerns of engineers has been the
design and implementation of appropriate lateral load resisting
systems. Recently, lateral load resisting systems have attracted
the attention of many engineers and researchers. One of
resistant elements against lateral loads is shear walls. Since
1970’s, a number of important structures using steel plate
shear walls have been designed and constructed in the United
States and Japan such as the 6-story Sylmar Hospital in
greater Los Angeles or The 35-story office building in Kobe,
Japan [1]. The first generation of shear walls is reinforced
concrete walls. These types of shear walls have little practical
application in the structures. The second generations of these
walls were steel plate shear walls (SPSW). In this type of
shear walls, the resistant core is of steel sheets instead of
reinforced concrete. These walls, in addition to having
sufficient stiffness, have high ductility. The third generations
of shear walls are called composite steel plate shear walls
(CSPSWs). In these walls the prefabricated reinforced
concrete walls or cast-in-place (CIP) concrete walls are
connected to the plate on one or both sides by studs. These
steel plates are effective in maximizing the steel plate capacity
and the delay in their buckling. In other words, the concrete
plate in these walls is an equivalent of stiffener in stiffened
SPSW. In many studies, CSPSW is known as steel sections
embedded in concrete along with reinforced concrete
connected to one another by shear connectors.
About CSPSWs with no openings many studies have been
conducted (e,g. [1, 2]). Rahai and Hatami [3] evaluated the
effects of shear studs spacing variation, middle beam rigidity
and the method of beam to column connection on the CSPSW
behavior. They found that increasing the shear studs spacing
reduces the slope of load–displacement curve and improves
ductility up to a specific studs’ spacing. Also, the effects of
middle beam rigidity and beam to column connections were
insignificant on the composite steel shear walls behavior.
Arabzade et al. [4] investigated the buckling load of a CSPSW
and suggested that the elastic buckling coefficients can be
used for determination of the number of bolts or the spacing
between the bolts. In another study, they stated that this
system has reliable behaviour if the columns have high
bending stiffness. Also bolts spacing to plate thickness ratio
has direct relationship with system ductility. However, plate
yield load has an inverse relationship with this ratio [5]. Dan
et al. [6] investigated maximum load capacity, stress and
strain distribution in structural components, interstory drifts,
cracking patterns, deformation and degradation capacity of
composite steel–concrete structural shear wall with steel
encased profiles. In the study of Hatami et al. [7], the effects
of fiber content/angle and panel width on the properties of
CSPSWs reinforced with carbon fibers were investigated.
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Results showed that wider panel widths enhance the behavior
of CSPSW. Higher fiber contents increase energy absorption,
stiffness, over-strength and capacity, but decrease ductility
values.
About CSPSWs with openings there are fewer studies that
necessitate the need to perform research in this area. For
example, Lin and Kuo [8] analyzed the ultimate strength of
shear wall with opening under lateral load. Their results
indicated that the shear strength contributed by diagonal
reinforcement around opening reached 40% of its yield
strength while the shear strength contributed by the
rectangular pattern reached 20% of its yield strength. Marius
[9] studied seismic behaviour of reinforced concrete shear
walls with regular and staggered openings after the strong
earthquakes between 2009 and 2011. Considering the low
amount of investigations in this area, in this paper our purpose
is to investigate the seismic behavior of a single CSPSW with
nine openings and different widths of 500, 1000, 1250, and
1500 mm. In this regard, effects of elastic stiffness, effective
stiffness, failure load, absorbed energy, and ductility ratio on
its performance were evaluated.
EXPERIMENTAL SPECIMEN
The specimen for the experiments was ½-scale three stories,
one bay CSPSW with steel moment frames with high and low
levels of mezzanine which was set up by [1]. We modeled it
in ABAQUS finite element software (see Fig. 1). They tested
the CSPSW system in two cases: system with a gap between
the concrete wall and the boundary columns and beams, and
the system with no gap. The height of the wall was 6197.6 m
and the span width was 2133.6 mm. Table 1 shows the
materials used for the system. The loading sequence applied
to both
Systems were cyclic shown in Figure 2. We used the
experimental results of this system for the verification of our
findings.
Table 1: Specifications of the test set-up
Components E (N/mm2) µ Fy Fu ∈ (𝒚) ∈ (𝒖)
Steel plate 200000 0.3 240 360 32.1 e 0.2
Columns and beams 200000 0.3 380 520 39.1 e 0.2
Bolt 200000 0.3 600 720 33 e 0.2
Figure 1: Experimental model tested by [1]
Figure 2: Loading Sequenced Applied to the experimental
model by [1]
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© Research India Publications. http://www.ripublication.com
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Test set-up
In this study a single span frame and a floor from a five-story
building were selected for the study. The five-story building
has CSPSW with installed openings symmetrically on all
sides. The span’s length is 3.50 meters and the ceiling height
in the lowest floor (test specimen) is higher than 3.50 m.
Figure 3 and 4 show the framing plan and the elevation of the
shear wall system. It was designed according to AISC-341
[10] standard. The properties of materials used in the test set-
up are the same as those used in the experimental model (table
1). The thickness of steel plate was 3 mm, the distance
between shear connectors (bolts) was 250 mm, and their
diameter was determined as 8 mm. With a total infrastructure
of 1700 square meters, the seismic load of the structure was
obtained as W= 12600 KN. According to Iranian seismic code
(No. 2800), since the building is of residential type (I=1.0)
located on soil type B, and Iran is considered to be located in
a high seismic risk region (i.e. base design acceleration
A=0.35) and also, the structure’s behavior coefficient with
respect to the CSPSW is as R=6.5, therefore, seismic
coefficient for the building was calculated as
135.0/ RABIC . Now, the base shear force can be
calculated as: KNWCV 170012600135.0 .
Due to the symmetry in plan and symmetrical seismic force
distribution, the contribution of each shear wall from the base
shear will be equal to 850 KN.
Figure 3: Framing plan of the test set-up
Figure 4: Shear wall system dimension
Numerical specimens
Two types of specimens in the set-up were a single CSPSW
with the designed specifications but with no openings shown
in Figure 5a which was modeled in ABAQUS software
(named as WOP) as specimen 1, and a single CSPSW with
nine openings embedded at different positions shown by
numbers 1 to 9 in Figure 5b as specimen 2. In the second
specimen, the width of the openings were 500, 1000, 1250,
and 1500 mm defined laterally and longitudinally as OP50-1
to OP50-9, OP100-1 to OP100-9, OP125-1 to OP125-9, and
OP150-1 to OP150-9..
(a)
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 10 (2016) pp 6890-6896
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(b)
Figure 5: A view of test specimens (a) CSPSW with no
openings, and (b) CSPSW with installed openings
Numerical parameters
To study the nonlinear static seismic behavior of specimens,
we investigated following parameters according to ASTM E
2126-07 [11] standard and calculated as the actual load-
displacement curve idealized in Figure 6:
i. Elastic stiffness (Ke): it can be expressed as a slope
measured by the ratio of the resisted shear load to the
corresponding displacement :
𝐾𝑒 =0.4𝑃𝑝𝑒𝑎𝑘
∆e
(1)
ii. Effective or secant stiffness (keff): which is the value
of lateral force divided by the lateral displacement on
force-displacement curve;
iii. Failure load (𝑃𝑢): which is the load corresponding to
the failure limit state on the envelope curve(Fig. 4). it
can be obtained as:
𝑃𝑢 = 0.8𝑃𝑝𝑒𝑎𝑘
(2)
iv. Absorbed energy (E): it is the area under envelope
curve from zero to ultimate displacement;
v. Ductility ratio (D): which is the ratio of the ultimate
displacement and the yield displacement.
Figure 6: Idealization of nonlinear response according to [11]
In this regard first we drew the force-displacement curve for
the specimens and then, according to ASTM E 2126-07
standard and the pushover curve, we obtained the values of
studied parameters for them.
NUMERICAL RESULTS
Following, we presents the results of comparing seismic
behavior of two test specimens in terms the above mentioned
parameters. In final section we provide overall results of
comparison.
Elastic stiffness
Comparing elastic stiffness of two specimens showed that
composite steel plate shear wall with no openings had higher
elastic stiffness value. Among different size of openings,
those with the size of 500 mm had the highest elastic stiffness,
and the difference of elastic stiffness between 500 mm and
1000 mm openings was greater compared to other dimensions
(see Fig. 7).
Figure 7: Elastic stiffness changes in CSPSW with and
without openings
Among opening with different zones, the opening No. 5 had
the highest elastic stiffness value. In other words, if the
symmetry of the structure is adhered and the opening is
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installed in the middle of the wall, we will have minimal
stiffness loss in the openings with any dimensions.
Effective stiffness
To compare the effective stiffness of two specimens we draw
the curve of effective stiffness for each opening with different
dimensions (see Fig. 8). In each four dimensions, it was seen
that 50% secant stiffness or effective stiffness loss occurs in
drifts between 1 and 2%. In other words, secant stiffness in
the models is reduced to about half in 40 mm to 80 mm
displacement (total displacement is 200 mm), and in
subsequent drifts, stiffness reduction occurs with a more
gentle slope. With increasing the size of openings, difference
of secant stiffness between the two specimens also increases,
and this difference decreases with the increase of drift. We
also found out that the location of openings does not have a
significant impact in reducing secant stiffness and this is true
for all dimensions of openings.
Figure 8: K-drift diagram
Energy absorption
One of the accurate ways of measuring seismic performance
of a structure depends on energy dissipation. all analyzed
specimens was measured as the area enclosed by load-
displacement curve. Absorbed energy of small size opening
(500 mm) in all zones on the wall except zones number 1, 3,
7, and 9 was higher compared to the system that had no
openings (see Fig. 9). Depending on the type of load,
pushover, and the nature of the seismic load which is cyclic,
results should be generalized for similar regions of the walls.
For example, if the direction of seismic loading changes, the
current situation of zone 9 will occur on zone 7. Similar to
stiffness changes, a significant reduction in absorbed energy
in the specimen with the opening of 500 mm and others is
evident. With larger openings, energy absorption changes in
different areas of the CSPSW is reduced (see Fig. 9)
Figure 9: Energy absorption changes in CSPSWs with and
without openings
Ductility ratio
Results showed that the wall corners have dramatic effects in
reducing its ductility. In different dimensions, the opening No.
5 was most effective in improving the ductility than other
openings. With larger openings, the ductility ratio changes in
different areas of the shear wall are reduced (see Fig.10). By
changing the direction of seismic loading, these conditions
created for zones 1 to 4 should also be considered for zones of
6 to 9.
Figure 10: Ductility ratio changes in CSPSWs with and
without openings
Failure load
In the CSPSW with installed openings, results showed that
failure load of the opening with the size of 500 mm were
higher compared to other dimensions, and 1000-mimimeter
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size opening had the second highest failure load value.
Reduction of failure load compared to the CSPSW with no
opening was seen in the openings with the size 1250 and 1500
mm. In the CSPSW with installed openings, the most affected
areas were in the corners. Although, considering the behavior
of the seismic load which is cyclic, reduction of failure load
was also seen in other areas. For example, in the direct
loading, the zone 1 was critical and in reverse loading, the
zone 3 becomes more critical in terms of failure load. This is
true for areas 7 and 9 (see Fig. 11).
Figure 11: Failure load changes in CSPSWs with and without
openings
Table 2 presents a summary of the results related to all
parameters mentioned above. In this table, for each size of
openings, its best conditions compared to the specimen with
no openings have been identified with colors where red color
shows the openings with the weakest performance. As can be
seen, for the dimension of 500 mm, because of the effect of
direct loading, openings located in zones 2, 4, 6 and 8 can be
selected as those with best performance. In other dimensions,
they were in zone 5.
Table 2: A summary of the results for the parameters of the
specimen with openings
Openings K D Pu E Openings K D Pu E
OP50-1 0.92 0.93 1.20 0.93 OP125-1 0.40 0.66 0.90 0.76
OP50-2 0.97 1.10 1.21 1.04 OP125-2 0.42 0.62 0.99 0.81
OP50-3 0.84 0.87 1.19 0.89 OP125-3 0.44 0.66 1.02 0.83
OP50-4 0.95 1.10 1.23 1.06 OP125-4 0.39 0.57 1.10 0.83
OP50-5 0.87 1.10 1.25 1.06 OP125-5 0.47 0.77 0.99 0.83
OP50-6 0.91 1.10 1.23 1.06 OP125-6 0.42 0.66 0.99 0.82
OP50-7 0.86 1.00 1.21 1.05 OP125-7 0.41 0.60 1.04 0.85
OP50-8 0.95 1.10 1.24 1.07 OP125-8 0.38 0.60 0.99 0.82
OP50-9 0.91 1.04 0.94 0.98 OP125-9 0.36 0.60 0.89 0.76
OP100-1 0.48 0.69 1.00 0.83 OP150-1 0.36 0.62 0.81 0.69
OP100-2 0.52 0.77 1.03 0.86 OP150-2 0.34 0.57 0.90 0.74
OP100-3 0.52 0.66 1.10 0.89 OP150-3 0.37 0.62 0.96 0.78
OP100-4 0.45 0.62 1.06 0.88 OP150-4 0.33 0.55 0.96 0.75
OP100-5 0.64 0.87 1.08 0.91 OP150-5 0.36 0.66 0.96 0.74
OP100-6 0.44 0.69 1.04 0.86 OP150-6 0.33 0.57 0.96 0.74
OP100-7 0.51 0.69 1.11 0.91 OP150-7 0.33 0.53 0.96 0.79
OP100-8 0.48 0.66 1.05 0.88 OP150-8 0.30 0.50 0.96 0.74
OP100-9 0.43 0.66 0.98 0.83 OP150-9 0.31 0.55 0.96 0.68
CONCLUSION
In this study we investigated the seismic behavior of
composite steel plate shear walls having openings with four
500, 1000, 1250 and 1500 mm dimensions located in nine
different areas of the wall. For this purpose, five parameters of
elastic stiffness, effective or secant stiffness, failure load,
absorbed energy, and ductility ratio related to the system with
openings were evaluated and compared to the system which
had no installed openings. Results showed that the specimen
with no openings had highest elastic stiffness while in the
specimen with nine openings, the one with 500 mm size had
the highest elastic stiffness and reduction of elastic stiffness
between the 500 and 1000 mm size openings were 50%.
Installing the openings in the center of the composite steel
plate shear wall increase the elastic stiffness and the change in
the stiffness in larger openings and in different areas was
subtle.
In the specimen with installed openings, secant stiffness
changes in 1 to 2 % drifts was reduced by about 50%. In drifts
higher than 2-5%, secant stiffness was reduced. Also, its
changes in different openings size and installation location
were not impressive. The absorbed energy in the composite
steel plate shear wall with the openings embedded in the
corner showed a sharp decrease. By increasing the opening
size above 1000 mm, the rate of change in energy absorption
in different areas was reduced, and the central zone had the
largest energy absorption by about 10% compared to other
areas.
In the composite steel plate shear wall with the openings
embedded in the corner, a significant reduction in ductility
was seen by about 30%, and the lowest reduction was
observed in the center area. Also, with bigger openings,
ductility ratio was reduced. In this system, the reduction of
failure load was observed in openings larger than 1000 mm,
and the corners had the lowest base shear capacity. Overall,
we concluded that installing the openings in the center of wall
(Zone 5) will have less reducing effects on elastic stiffness,
effective or secant stiffness, failure load, absorbed energy, and
ductility ratio, and it should be avoided from embedding
openings in the corners of the composite shear wall as much
as possible, especially those with larger sizes.
ACKNOWLEDGMENTS
This paper was extracted from a MSc thesis in civil
engineering structure prepared by Soheil Kordbegli approved
in 2015 by Faculty of Engineering, Islamic Azad University
of West Tehran Branch in Iran.
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