a seismic design of the underground box-type rc …
TRANSCRIPT
A SEISMIC DESIGN OF THE UNDERGROUND BOX-TYPE RC
STRUCTURE CONSIDERING THE THREE-DIMENSIONALITY
Hideki NAGAI1, Tadashi KAWAI
2, Motoki KAZAMA
3
ABSTRACT
A seismic evaluation method is proposed for determination of planar shear deformation of a shear wall,
considering the three-dimensionality, which is an underground box-type structure such as screen chamber and
pump chamber of intake facilities in large-scale energy power plants. In underground box-type structures, as
results of large-scale ground motion side walls that are perpendicular to the direction of ground motion is pushed
by the ground, hence earth pressure acting on the side wall centre is reduced by the deformation occurred due to
the decrease in the rigidity. On the other hand, earth pressure acting on the side wall end and the shear force
acting on the shear wall surface is increased, resulting in in-plane shear deformation of the shear wall, which can
lead to cases where critical breakage of the entire structural system occurs. In this case, a method for calculating
the limit value of deformation angle “limit deformation angle” is proposed by applying the index of structural
member’s deformation angle to the damage index of the shear wall of an underground box-type structure, and
the validity of this method is verified by utilising it in a seismic evaluation.
Keywords: Underground RC structure, Numerical analysis, Damage index, Centrifuge experiment, three
dimensionalities
1. INTRODUCTION
This paper proposes the new seismic design procedure considering the three-dimensionality of the
underground box-type RC structure subjected to seismic motion, based on the results of centrifuge
model vibration test and 3D nonlinear dynamic analysis. As a performance-based earthquake
engineering, it is to purpose of performing seismic evaluation of an underground box-type structure,
such as screen chamber and pump chamber of intake facilities in large-scale energy power plants with
each side wall surrounded by soil.
This box type structure is connected to multiple culvert and a structural joint is given between the two,
and there is an opening on the first floor as shown in Figure 1. Two-dimensional analysis by two-
dimensional sliced cross section has been carried out until now, but seismic design method
considering three-dimensionality is proposed in this paper.
(a) Image of overall structure (b) Name of structure members
Figure 1. An underground box-type structure
1 Deputy general manager, Obayashi corporation, Tokyo, Japan, [email protected]
2 Associate professor, Tohoku University, Sendai, Japan, [email protected]
3 Professor, Tohoku University, Sendai, Japan, [email protected]
Multiple culvert
Structural joint
Pump chamber
Direction of the input wave
Base slab
Shear wall
Front -back wall
Opening
2
2. CENTRIFUGE EXPERIMENT
2.1 Outline of experiment
A centrifuge model vibration test is performed to confirm 3D seismic behavior of underground box
type structure and the load acting on each member of the structure, as shown in Figure 2. The box type
structure, which is 1/50 scale model with an opening on lower part of one of its side wall surface, was
made of aluminum and the wall thickness is 12 mm. The outer dimensions of the model are 250 mm
×350 mm in planar shape and 350 mm in height (actual size scale, planar shape 12.5 m×17.5 m, height
17.5 m). Here, the material physical properties of the aluminum material are elastic modulus
E=7.00×107
kN/m2, Poisson's ratio νA=0.30, yield stress σsy=1.00×10
5 kN/m
2. It is put in the central
part of the shear soil tank in the centrifuge apparatus.
Upper layer of ground is a sand and lower layer is a cement improved soil. The sand layer is made of
Gifu's No.7 silica sand (Gs=2.645, γmax=1.529 g/cm3, γmin=1.184 g/cm
3) and aimed at a relative density
of 70% (γd=1.406 g/cm3) by compacted, which is C=50.1 kN/m
2, φ=36.0°, according to the
consolidated non-drainage (CU) triaxial compression test (JGS 0523) of the soil.
The cement improved soil was formed in the lower layer of the shear soil tank, and the thickness was
150 mm with the same height as the load cell. The uniaxial strength qu of the cement improved soil is
1.51 MN/mm2, and the modulus of elasticity is 3.24×106 kN/m2.
Input waves are the sign waves of 100 Gal, 200 Gal, and 400 Gal, inputted from undersurface of the
shear soil tank. Accelerometers, displacement gauges, earth pressure gauges, shear stress meters and
load cells were used as the measurement of the experiment.
(b) Material of closing the opening
(a) Shear soil tank and box type structure model (c) Picture of box type structure and gauges
Figure 2. Centrifuge model vibration test
2.2 Experiment results
2.2.1 Classification of applied load
As the results of experiment, increase of the applied load and its convergence situation due to gradual
increase of the input waves has been revealed by classifying the load acting on each structural
member, as shown in Figure 3.
Front-back earth pressure force and circumferential shear force, which are main loads except inertia
force, show the little increase rate from 200 Gal to 400 Gal against increasing tendency until 100 Gal.
Here, the front-back earth pressure is taken as the sum of earth pressure on the two side walls
perpendicular to the input wave direction.
250
160
L150(t=9mm)
Rubber(t=15mm)
Boltφ5mm
4-PL6mm 160
Rubber(t=15mm)
150
316
L150(t=9mm)
4-PL6mm
Boltφ5mm
3
The circumferential shear force tends to converge first comparing with front-back earth pressure force
and inertial force. The inertial force increases approximately linearly as the input acceleration
amplitude increases. The ratio of the inertial force to the total horizontal force is approximately 20% or
less, and its ratio is small like general underground culvert structure. In the ratio to the total horizontal
force, the front-back earth pressure was the largest, and the circumferential shear force was the second.
Figure 3. Relationship between acting force and ground response displacement of each case
2.2.1 The distribution of front earth pressure
The distribution of earth pressure acting on the front wall at the time, when the largest load in the
historical data is calculated, is shown in Figure 4. The earth pressure of the opening side and the
central part, due to deformation of the structure against the deformation of the ground, has little
change even if the input acceleration is increased. Especially, the earth pressure of the central part is
50% or less compared with earth pressure at the end of the front wall.
On the other hand, earth pressure at the end of the front wall increases due to the rigidity of the
structure and the response displacement of the surrounding soil. Earth pressure at the end of the front
wall approaches to static passive earth pressure (σp=Kp·σv, where Kp=tan2(π/4+φ/2), σv: effective
weight of the ground kN/m2) in 400 Gal. This is because the deformation of the shear wall is small and
the relative displacement between the ground and the structure increases.
Figure 4. Distribution of earth pressure acting on the front wall
2.2.3 Deformation of the entire structure
Planar maximum deformation of the front wall and the shear wall is summarized as shown in Figure
5(a). The relationship between the out-of-plane deformation angle of the front-back wall and the in-
plane deformation angle of the shear wall, and the relationship between the out-of-plane deformation
angle of the front-back wall and the torsional deformation angle of the shear wall are shown in Figure
Dir. of input waveS-side
W-side Shear wall
Opening sideN-side
Deformation
0 150 300Earth pressure(kPa)
100Gal
200Gal
400Gal
Ho
rizo
nta
l lo
ad (
MN
)
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
Response displacement(mm)
Response displacement(mm)
Ho
rizo
nta
l lo
ad (
MN
)
Ho
rizo
nta
l lo
ad (
MN
)
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)
応答変位(mm)
400Gal200Gal100Gal
-80
-40
0
40
80
-300 -200 -100 0 100 200 300
荷重
(MN
)応答変位(mm)
400Gal200Gal100Gal
Response displacement(mm)
Response displacement(mm)
Ho
rizo
nta
l lo
ad (
MN
)
0
20
40
60
80
0 50 100 150 200 250 300
作用水平荷重(M
N)
自由地盤の応答地盤変位(mm)
前背面土圧 周面せん断力
慣性力 全水平力
100Gal
200Gal400Gal
Ho
rizo
nta
l lo
ad (
MN
)
Response displacement of free field (mm)
Front-back
earth pressure
Inertial force
Circumferential
shear force Total force
Dir. of the input wave
Earth pressure gauge
Front
Planar view
Total force
Front-back earth pressure force
Circumferential shear force
Load
Inertial force
4
5(b). For the out-of-plane deformation angle of the front-back wall and the in-plane deformation angle
of the shear wall, it was confirmed that the approximate straight line was y=0.38x, and in-plane
deformation of the shear wall occurred. As the results, in the case of concrete wall members, because
out-of-plane fracture (limit value of deformation angle of out-of-plane bending interlayer :1.0%) and
in-plane fracture (limit value of deformation angle of in-plane shear strain of RC wall :0.4%) is 1: 0.4,
it is assumed that the shear wall and the front-back wall are destroyed almost at the same time. For the
out-of-plane deformation angle of the front-back wall and the torsional deformation angle of the shear
wall, the approximate straight line is y=0.33x, and even if the input wave’s direction is one direction,
the torsional deformation was proved to be occurring. we found that it was necessary to always
consider deformation in both directions (out-of-plane, in-plane) in the shear wall. In seismic
performance evaluation, it is necessary to select an analysis method that can take three-dimensional
deformation into consideration.
(a) Maximum deformation of planar view (b) Rrelationship of deformation angle
Figure 5. Relationship of deformation angle between front wall and shear wall
3. 3D-NUMERICAL ANALYSIS
3.1 Experimental verification analysis
Detailed time history dynamic analysis by 3D FEM model was carried out to confirm the
reproducibility of the experiment. The finite element analysis program "FINAL-GEO" developed by
Obayashi Corporation was used. This analysis program has many verification results in the concrete
material constitution model and also has a modified GHE model as a structural model of the ground.
In addition, the computational speed has dramatically increased from the conventional speed by using
simultaneous equation solving method suitable for large-scale high-speed operation. Geometric
nonlinearity is not considered in the analysis. The calculation method of dynamic analysis applies the
Newmark-β method.
In the analysis model, the structure is a shell element, and the ground is a hexahedral solid element.
The number of elements of the structure is 1870, and the number of elements of the ground is 74500.
Also, the shell element has 5 degrees of freedom, and the hexahedral solid element has 3 degrees of
freedom. Repeated triaxial tests were carried out to determine the deformation characteristics of the
ground material for silica sand No.7 (Dr=70%), and the fitting by the H-D model which is the skeleton
curve of the modified GHE model was performed. The nonlinear relationships between stiffness
(G/G0), damping ratio (h) and strains in the upper layer of ground are modelled by the modified GHE
model. Relationship between the dynamic shear coefficient and the damping constant of the ground
used for the modified GHE model (G-γ, h-γ) is shown in Figure 6. The history law can satisfy arbitrary
G/G0-γ relation, h-γ relation and strength characteristic (upper limit value of shear stress) by
y = 0.38x
-0.2
-0.1
0
0.1
0.2
-0.2 -0.1 0 0.1 0.2
せん断壁の
面内変形
(%)
前面壁の
面外変形角(%)
400Gal
200Gal
100Gal
Deformation angle
of front wall (%)
Def
orm
atio
n a
ngle
of
shea
r w
all
(%)
Dir. of input wave
y = 0.33x
-0.2
-0.1
0
0.1
0.2
-0.2 -0.1 0 0.1 0.2
せん断壁の
面外変形角
(%)
前面壁の
面外変形角(%)
400Gal
200Gal
100Gal
Deformation angle
of front wall (%)
Def
orm
atio
n a
ngle
of
shea
r w
all
(%)
Dir. of input wave
t=12s
t=11.5s
振動前位置Before deformation
Opening-side
Shear wall-side -0.1
0.1(%)
-0.1 0.1(%)
5
improving the Masing rule.
(a) Analysis model (b) G/G0-γ relation and h-γ relation
Figure 6. Analysis model of soil and structure system
3.2 Confirmation of reproducibility
The time history analysis was carried out in good convergence. Overall deformation is shown in
Figure 7. Relationship between displacement and horizontal force is almost the same as the above
tests results as shown in Figure 8. The comparison of deformation of planar view is shown in Figure 9,
as the results, the both results are almost the same.
The load and the deformation of an underground box-type structure computed by the dynamic analysis
are confirmed to become almost the same as the above tests results. It was confirmed that in-plane
deformation and torsional deformation of the shear wall occurred.
Figure 7. Overall deformation (200Gal) Figure 8. Relationship between displacement and force
Figure 8. Relative displacement of structure(400Ga
Figure 9. Deformation of planar view
解析は3次元地盤―構造物連成問題とし、地盤は 3次元ソリッド要素でモデル化し、箱型構造物は 3次
元シェル要素でモデル化した。構造物と地盤間にはジョイント要素で連結する。図 1-1~図 1-5 に解析モデ
ルを示す。
550
500
1200 1200
500
550 Strain of soil
Dam
pin
g r
atio
Opening side
Shear wall side
-0.1
0.1(%)
-0.1 0.1(%)
N-side S-side
Experiment ( - dir.)
Analysis ( - dir.)
Experiment ( + dir.)
Analysis ( + dir.)
Before deformation
Earth pressure of
front & back
Interrail force
Circumferential
shear force
Total force
Solid line : Analysis
Dot line : Experiment
Displacement of free ground
Ho
rizo
nta
l fo
rce
(MN
)
6
4. A NEW DESIGN METHOD CONSIDERING 3-DIMENSIONALITY OF STRUCTURE
4.1 A new design method considering three dimensionalities
Dynamic analysis of 3D FEM model takes a lot of time and cost, so it is difficult to evaluate all the
designed ground and structure systems. Therefore, we propose a new design method considering three
-dimensionality. Design flow of the new design method for an underground box-type structure is shown in
Figure 10. Earthquake resistance assessment is performed by using detailed nonlinear dynamics below
seat of 3D FEM model. The method for calculating the index of "critical deformation angle" applied in
the design method is introduced in next section. The maximum response deformation angle of the
shear wall is obtained by acting the seismic wave of coupled analysis. And finally, it is a value smaller
than the critical deformation angle. It is a simple checking method to compare the critical deformation
angle and the maximum response deformation angle.
Figure 10. Design flow of an underground box-type structure
4.2 Calculation method of “limit deformation angle”
For the various assumed load distributions, the critical deformation angle of the shear wall of the box
type structure was calculated as shown in Table 1, by load control gradual increase analysis by the
three-dimensional laminated shell model. We changed the load distribution in the depth direction to
the front wall and the shear wall to parametric in the examination series of K1 ~ K6. The relationship
between the horizontal load and the shear deformation angle of the shear wall is determined in this
analysis. When the wall member reaches the horizontal yield strength (maximum value) in the in-
plane direction and undergoes in-plane shear deformation, it becomes brittle (sharply decreasing the
horizontal yield stress). The deformation angle at the time when the horizontal yield strength is
reached is calculated as the critical deformation angle. It is possible to obtain the minimum critical
deformation angle of the box type structure with respect to the shear wall, and it can be a threshold
value of the damage index used in the seismic evaluation. The method of calculating the critical
deformation angle is proposed by the following study.
Table 1 shows the results of determining the critical displacement angle of each case. The load -
Setting of structure dimension
2D section model※
・Feature of design method
Design of section
Design of shear wall
・Feature of analysis method
2D FEM model
Spring-frame model
Calculation of Limit value (Rd)
・Limit deformation angle
・Load step analysis by 3D model
Calculation of Response (Sd)
・Response of deformation angle
・Dynamic analysis by 3D model
NGRd > Sd
Verification
END
OK
2D Model 3D Model
YES
YESNO
NO
※ Guideline and recommendation for
seismic performance verification of underground reinforced concrete structures in nuclear power stations.
START
Classification by parameter of structure shape
Classification by structure arrangementand soil condition
Specified
Proposal
In this paper, the explanations of classification are omitted.
7
displacement curves of each case are shown in Figure11 and Figure12. In-plane shear deformation of
the shear wall preceded by the load distribution of the lower triangle (K3-3) with the load of only the
peripheral shear stress, resulting in the smallest shear deformation angle (=0.462%). From this, we
propose a case where circumferential shear force acts on the shear wall with a lower triangular
distribution as a method for finding the minimum value of the critical deformation angle.
Table 1. Evaluation result of critical deformation angle*
No. Struct
ure Load type
Loading
place Load distribution
Limit
deformati
on angle
(%)
K1
Openi
ng
Acceleration All walls Uniform distribution 0.621
K2-1 Front and
back earth
pressure
Front
back wall
Uniform distribution 0.853
K2-2 Upper triangular distribution 0.644
K2-3 Lower triangular distribution 0.650
K3-1 Circumferen
tial shear
force
Shear
wall
Uniform distribution 0.787
K3-2 Upper triangular distribution 0.956
K3-3 Lower triangular distribution 0.462
K4-1
Front and
back earth
pressure
Circumferen
tial shear
force
All walls
Lower triangular 75% (front and back wall side)
Lower triangular 25% (shear wall side) 0.625
K4-2 Lower triangular 50% (front and back wall side)
Lower triangular 50% (shear wall side) 0.760
K5-1
Front and
back earth
pressure
Circumferen
tial shear
force
The
lower
half of all
walls
Uniform distribution 75% (front and back wall
side)
Uniform distribution 25% (shear wall side)
0.691
K5-2
Uniform distribution 50% (front and back wall
side)
Uniform distribution 50% (shear wall side)
0.565
K6
Response
displacemen
t method
All walls Ground spring + Response displacement 0.491
* Calculated by the three-dimensional laminated shell model
Figure 11. Relationship between shear deformation angle and load (K1, K2, K3)
Lower
triangular Upper
triangular Uniform
distribution Uniform
distribution
Inertial force Earth pressure distribution
Shear deformation angle
Inertial force Uniform distribution Upper triangular Lower triangular
Ho
rizo
nta
l fo
rce
(kN
)
Shear deformation angle
Ho
rizo
nta
l fo
rce
(kN
)
Uniform distribution
Upper triangular
Lower triangular
8
Figure 12. Relationship between shear deformation angle and load (K4, K5)
4.3 Case study in actual structure
4.3.1 Analysis condition
3D nonlinear dynamic analysis of a box type structure only, which is a structure of real size with an
opening, simulating real structures, is performed. The target structure is a two-story box-shaped
structure, the outer shape is 23.9 m (side wall width perpendicular to the direction of the input
horizontal seismic wave) ×32.1 m (side wall width parallel to the direction of the input horizontal
seismic wave) ×29.0 m (height), as shown in Figure13. The structure has an opening on the lower first
floor of one side wall having four walls. As a coupled model, the structure and the ground were
hexahedral solid elements (number of elements: 37060, number of nodes: 59740).
The structure is a foundation structure which is directly installed on the rock (CM class), and the
ground constituent law is based on the rock under the structure as an elastic body. For the upper layer
of soil, a modified GHE model that can account for the nonlinearity of the ground is applied.
The analysis software is a large-scale, high-speed nonlinear finite element method program "FINAL-
GEO" which can greatly shorten the calculation time.
Figure 13. Target structure of a two-story box-shaped structure
Ho
rizo
nta
l fo
rce
(kN
)
Shear deformation angle
Fornt:1.00, Shear:0.00
Fornt:0.75, Shear:0.25
Fornt:0.50, Shear:0.50
Shear deformation angle
Ho
rizo
nta
l fo
rce
1st, Uniform dis. ,Fornt:1.00, Shear:0.00
1st, Uniform dis. ,Fornt:0.75, Shear:0.25
1st, Uniform dis. ,Fornt:0.50, Shear:0.50
Section[1] Section[2]
Shear wall
2.0m
3.0m
23.9m
32.1m
29.0m
Front - back wall
h
Dam
pin
g r
atio
(h
)
Sti
ffn
ess
(G/G
0)
Shear strain ()
G/G0
Middle Deck
Dir. of input wave
1st floor
2nd
floor
Location of opening
9
4.3.2 Analysis results
In the underground box-type structure, as the results of large-scale ground motion, front-back walls
that are perpendicular to the direction of ground motion is pushed by the ground, hence earth pressure
acting on the front wall centre is reduced by the deformation occurred due to the decrease in the
rigidity. On the other hand, acting earth pressure on the front wall end and the shear force acting on the
shear wall surface is increased, resulting in in-plane shear deformation of the shear wall, which can
lead to cases where critical breakage of the entire structural system occurs.
Input seismic waves are shown in Figure14. Input range of analysis is 30.0s to be shorten analysis
times. In original input wave, overall deformation and crack graph of the structure are shown in
Figure15. Maximum deformation angle of shear wall occurs in 8.4s of input range to analysis. Then,
the large strain of rebar and minimum principal strain of concrete occur in the lower end of front-back
wall and lower of shear wall as shown in Figure16 and Figure17. In 3times input wave, compression
softening in lower of shear wall is expended as shown in Figure18.
Figure14. Input wave motions (NS-dir., UD-dir., original)
Horizontal (X dir.) Vertical (Z dir.)
Figure16. Rebar strain distribution (t=8.4s)
Section[1] Section[2]
Figure17. Minimum principal strain distribution (t=8.4s)
Figure15. Analysis results (Deformation, Crack)
全体変形図 (変位倍率:100) ひび割れ図
5.0s
8.4s
(最大
層間変
形時)
15.0s
Overall deformation Crack graph
Max
deform
ation
angle
Section[1]
2000
1600
1200
800
400
0 (μ)
2000
1600
1200
800
400
0 (μ)
Section[2]
0
-200
-400
-600
-800
-1000 (μ)
10
Original of input wave
(Maximum amplitude of acc. 460Gal) 3 times of input wave
(Maximum amplitude of acc. 1380Gal)
Figure 18. Crack graph at maximum interlaminar deformation
4.3.3 Seismic safety judgment of structure system
The evaluation is based focusing on "shear deformation angle of shear wall”. In this case, a method for
calculating the limit value of deformation angle, which is “limit deformation angle”, is proposed by
applying the index of structural member’s deformation angle to the damage index of the shear wall of
an underground box-type structure. As the results, Figure 19 shows the result of obtaining the member
deformation angle of the time history from the response displacement of the three-dimensional
coupled analysis. Here, the horizontal axis is the shear deformation angle of the shear wall of the
whole-time history, and the vertical axis is the horizontal load applied to the lower end of the shear
wall at that time. In the case of seismic wave 6 times the limit deformation angle occurred and the
deformation angle exceeded. The deformation angle (θmax=0.695%) at the response load peak shows a
value larger than the critical deformation angle (θu=0.365%) which was analysed as the proposed
method by using the structure model of hexahedral solid elements, which is the verification of the
applicability of the critical deformation angle calculation method.
The response maximum deformation angle of the shear wall and front-back wall that was obtained by
loading original, 3 times and 6 times seismic waves of coupled analysis, as shown in Table 2 and
Table 3. In case of 3 times seismic waves, the breakage of the shear wall was occurred first and the
deformation angle of shear wall became a larger value (Sd/Rd =1.03) than “limit deformation angle”.
Figure 19. Relationship between "Out-of-plane deformation angle of member"
and "Horizontal load at lower end of wall"
Table 2. Evaluation result of shear wall
Input wave Original 3 times 6 times
Maximum deformation angle, Sd 0.132 0.377 1.281
Limit deformation angle, Rd 0.365
Examination result, Sd/Rd 0.36 1.03 3.51
Judge OK NG NG
Deformation ratio:100times
(a) Shear wall
0.0E+00
2.0E+05
4.0E+05
6.0E+05
8.0E+05
1.0E+06
0 0.5 1 1.5 2
水平荷重(M
N)
せん断変形角(%)
地震波6倍 地震波3倍
地震波1倍 限界変形角
θmax=0.695
θu=0.365
Ho
rizo
nta
l lo
ad (
kN
)
Deformation angle (%)
6 times
3 times
Original
Limit angle
0.0E+00
1.0E+05
2.0E+05
3.0E+05
4.0E+05
5.0E+05
0 0.5 1 1.5 2
水平荷重(kN)
変形角(%)
地震波6倍 地震波3倍
地震波1倍 限界変形角
θmax=1.078
θu=0.996
(b) Front-back wall
Deformation angle (%)
6 times
3 times
Original
Limit angle
Ho
rizo
nta
l lo
ad (
kN
)
Concrete element that led to compression softening
Open crack
11
Table 3. Evaluation result of front and back wall Input wave Original 3 times 6 times
Maximum deformation angle, Sd 0.220 0.559 1.554
Limit deformation angle, Rd 0.996
Examination result, Sd/Rd 0.22 0.56 1.56
Judge OK OK NG
5. CONCLUSION
(1) As the results of the centrifuge model vibration test and the detailed time history dynamic analysis
by 3D FEM model, we confirmed that it was necessary to select an analysis method that can take
three-dimensional deformation into consideration in seismic performance evaluation.
(2) In designing RC structure, in-plane shear failure of the shear wall is a brittle fracture that causes a
sharp drop in the horizontal yield strength. Therefore, to grasp the damage mode preceding such
fracture, it is necessary to evaluate by a simple method in advance. The deformation and failure
modes of the entire structure can grasp easily by evaluating the inspection of the entire structure
and the out-of-plane and in-plane destruction of each member with one index of only the
deformation angle. It is necessary to grasp the macro response of the whole structure and it is
considered that the proposed method will be useful.
(3) The proposed seismic evaluation method is a simple checking method to compare the critical
deformation angle and the maximum response deformation angle. We expect it to be carried out by
actual seismic performance evaluation in the future. The evaluation results and the proposed
method in this paper are the result of examination by a box type structure with a simplified
structure assuming horizontal stratification ground, and it is necessary to pay attention to the scope
of its application.
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