simple strut model for evaluating infill-frame...
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Simple strut model for evaluating infill-frame interaction
Yasushi SANADA, Osaka Univ., Japan
Collapse
By Padang Ekspres
Modelate
damage
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
2007 Sumatra earthquakes of 8.4 and 7.9 ML
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Collapse
By Padang Ekspres
Modelate
damage
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
2007 Sumatra earthquakes of 8.4 and 7.9 ML
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Structural type
*3-story
*R/C with Brick Infill Walls
*3-story
*R/C with Brick Infill Walls
Structural type
Comparisons between collapsed/moderately damaged buildings
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
*E0=0.15 to 0.20
*E0=0.15 to 0.20
according to Japanese standard
according to Japanese standard
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Structural type
*3-story
*R/C with Brick Infill Walls
*3-story
*R/C with Brick Infill Walls
Damage level
Damage level Structural type
*Collapse
*Moderate
Why?
Comparisons between collapsed/moderately damaged buildings
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
*E0=0.15 to 0.20
*E0=0.15 to 0.20
according to Japanese standard
according to Japanese standard
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Damage level
Damage level
*Collapse
*Moderate
Why? Amount of Brick Infill?
Comparisons between collapsed/moderately damaged buildings
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Conclusion
Brick Infill contributed to the seismic
performance of buildings
Smaller
Larger
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Preparation of R/C frame specimen
Experimental Approach
φ4@100
700
55
01
,00
0600
2,1
50
700
325 800 800 3002,250
100
140
140
1214-φ9
4-φ9
φ4@100Lower beam
a'
a
a-a'
b-b'
b b'
Upper beam
D10
12-D19
12-D19
D10
2 x 40%-scale R/C one-bay
frame specimens,
representing 1st-story of the
surviving building
Uppre beam
Lower beam
Mortar20mm
Brick Wall 140mm
a'
a
70
0550
1,0
00
600
70
0
325 800 800 3002,250
2,1
50
a-a'
Preparation of R/C frame specimen
φ4@100
700
55
01
,00
0600
2,1
50
700
325 800 800 3002,250
100
140
140
1214-φ9
4-φ9
φ4@100Lower beam
a'
a
a-a'
b-b'
b b'
Upper beam
D10
12-D19
12-D19
D10
Brick wall
Experimental Approach
Preparation of brick wall specimen
Cutting from moderately
damaged building
Experimental Approach
Preparation of brick wall specimen
Cutting from moderately
damaged building
Transporting to
Toyohashi Univ.
Experimental Approach
Transported
Infill
Cutting from moderately
damaged building
Transporting to
Toyohashi Univ.
Preparation of brick wall specimen
Seismic
Testing
Experimental Approach
Test set-up and loading program
Test set-up
Loading program
– Vertical loading: Constant (183.4 kN)
– Horizontal loading: Cyclic (1/8001/12.5)
EastWest
PositiveNegative
2000 kN Vertical jacks 1000 kN Horizontal jack
West East
1750
450
400 Steel Box
Steel Box
Experimental Approach
-200
-100
0
100
200
-2 -1 0 1 2
Lat
eral
For
ce(k
N)
Drift Ration (%)
柱の曲げひび割れ
BF
Qmin = -34.5 kN
Qmax = 36.75 kN
Lateral force vs. drift ratio
Infilled Frame R/C Bare Frame
Experimental Approach
-200
-100
0
100
200
-2 -1 0 1 2Lat
eral
For
ce (kN
)
Drift Ration (%)
柱、壁の分離
柱の曲げひび割れ
壁のせん断ひび割れ
柱のせん断ひび割れ
主筋の降伏
帯筋の降伏
柱のせん断破壊
△
▲
×
IFQmax = 163.5 kN
Qmin = -174 kN
△
▲
×
-200
-100
0
100
200
-2 -1 0 1 2
Lat
eral
For
ce(k
N)
Drift Ration (%)
柱の曲げひび割れ
BF
Qmin = -34.5 kN
Qmax = 36.75 kN
Lateral force vs. drift ratio
Infilled Frame R/C Bare Frame
Experimental Approach
Comparison of performance curves
-200
-150
-100
-50
0
50
100
150
200
-10 -7.5 -5 -2.5 0 2.5 5 7.5 10
La
tera
l fo
rce
(kN
)
Drift ratio (%)
QIF=174.0kN
QBF=28.5kN
2.8% 1.6%
Experimental Approach
Damage level
Damage level
*Collapse
*Moderate
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Conclusion
Brick Infill contributed to the seismic
performance of buildings
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Simple strut model for evaluating infill-frame interaction
Yasushi SANADA, Osaka Univ., Japan
W = 0.25 dm (Paulay and Priestley)
cos
-1 W
c hc
αc : the ratio of the column contact length to the
height of the column (El-Dakhakhni et al.)
Strut width w:
dm
H h
Introduction
Strut Model
where 4.0175.0
hW (Stafford-Smith and Carter)
mgc
m
hIE
tE
4
2sin
Modeling of Infilled Frame
Strut width (W) = ? Contribution of infill to
strength/stiffness
Infill
deformation : iδ Column
deformation: cδ Infilled frame
deformation
Flexural
deformation
Shear
deformation
Frame/Infill
contact length
Infilled frame
Q
y: intersection point
iδ = cδ
yhs
h
Ch hs
cδ
Q
Mu
Qu
Evaluation of cδ
Moment
diagram
Column
Displacement: cδ(y)
432 ..24/1..6/1..2/11
yCyQyMIE
y huu
cc
c 0 ≤ y ≤ hs.
Column displacement:
)(2
2
yMdy
xdEI )(yxEI
Double Integration
hs θ
hs
h
Ch
fm
f 'm
=
fm
Q
Cs
wh
L
hs
h
Ch
fm
f 'm
=
fm
Q
Cs
wh
L
f’m = 0.65 fm
Equivalent
stress block
Evaluation of cδ
Moment
diagram
Column
Displacement: cδ(y)
)(2
2
yMdy
xdEI )(yxEI
Double Integration
yhs
h
Ch hs
cδ
Q
Mu
Qu
θ=0
Column displacement:
hs ≤ y ≤ h :
)..24/1..6/1
...4/1.2/1...6/1(1
43
223
shsh
shuhu
cc
c
hCyhC
yhCMyhCQIE
y
iδ
θ
θ
Infill : uniform shear deformation
yy ii
h
hyci
Evaluation of iδ
yy ic
Finding intersection height
(Newton Raphson Method)
hs
hs: Infill/frame contact length w = hs cos θ
Infill/Frame Contact Length
hs : intersection height
yy ic
Finding intersection height
(Newton Raphson Method)
hs: Infill/frame contact length
Infill/Frame Contact Length
hs : intersection height
w = hs cos θ 2
-200
-100
0
100
200
-2 -1 0 1 2Lat
eral
For
ce (kN
)
Drift Ration (%)
柱、壁の分離
柱の曲げひび割れ
壁のせん断ひび割れ
柱のせん断ひび割れ
主筋の降伏
帯筋の降伏
柱のせん断破壊
△
▲
×
IFQmax = 163.5 kN
Qmin = -174 kN
△
▲
×
-200
-100
0
100
200
-2 -1 0 1 2
Lat
eral
For
ce(k
N)
Drift Ration (%)
柱の曲げひび割れ
BF
Qmin = -34.5 kN
Qmax = 36.75 kN
Lateral force vs. drift ratio
Infilled Frame R/C Bare Frame
Application to Test Specimen
Evaluation of Infill Contribution
-200
-100
0
100
200
Lat
eral
for
ce (
kN)
-2 -1 0 1 2
Drift ratio (%)
Experiment
IF_FB
-200
-100
0
100
200
-2 -1 0 1 2
Lat
eral
For
ce (kN
)
Drift Ration (%)
柱、壁の分離
柱の曲げひび割れ
壁のせん断ひび割れ
柱のせん断ひび割れ
主筋の降伏
帯筋の降伏
柱のせん断破壊
△
▲
×
IFQmax = 163.5 kN
Qmin = -174 kN
△
▲
×
-200
-100
0
100
200
-2 -1 0 1 2
Lat
eral
For
ce(k
N)
Drift Ration (%)
柱の曲げひび割れ
BF
Qmin = -34.5 kN
Qmax = 36.75 kN
Lateral force at the same drift ratio
2cos..
d
twEK m
hs= 312 mm
Strut width : Initial lateral stiffness of infill:
hs = y
w = 2 hs cos
= 515 mm
Contact length:
= 112.6 kN cos... mftwQ
Verification of Analytical Model
Lateral strength of infill:
-200
-100
0
100
200
Lat
eral
for
ce (
kN)
-2 -1 0 1 2
Drift ratio (%)
Analysis
Experiment
Seismic Performance of Infilled R/C Frame
Q
Cs
hs
h
Ch
Cs/2 cos θ Qu
Qt Qu
Qt
-300
-200
-100
0
100
200
300
Lat
eral
for
ce (
kN)
-4 -2 0 2 4
Drift ratio (%)
Test Model
tsu QCQQ cos2/
Lateral strength of
overall infilled frame:
Conclusions
A simplified analytical method was proposed to evaluate infill
contribution to the seismic performance of masonry infilled RC frames,
and was verified through our structural test.
In the proposed analytical method, an infill panel is replaced by a
diagonal compression strut.
Compression strut width was determined with contact length between
column and infill.
Contact length was evaluated based on the compression balance at the
infilled/frame interface and lateral displacement compatibility under
column flexural and infill shear deformations.
The performance curve of the infill in the experimental specimen was
simulated by the proposed method. Consequently, a good agreement was
observed between experimental and analytical results.
Thank you for your attention