Yasushi SANADA

Simple strut model for evaluating infill-frame interaction
Yasushi SANADA, Osaka Univ., Japan
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
2007 Sumatra earthquakes of 8.4 and 7.9 ML
By Padang Ekspres
Modelate
damage
Collapse
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
2007 Sumatra earthquakes of 8.4 and 7.9 ML
By Padang Ekspres
Modelate
damage
Collapse
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Comparisons between collapsed/moderately damaged buildings
Structural type
*3-story
*R/C with Brick Infill Walls
*E0=0.15 to 0.20
according to Japanese standard
Structural type
*3-story
*R/C with Brick Infill Walls
*E0=0.15 to 0.20
according to Japanese standard
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Comparisons between collapsed/moderately damaged buildings
Structural type
Damage level
*3-story
*Collapse
*R/C with Brick Infill Walls
*E0=0.15 to 0.20
Why?
according to Japanese standard
Structural type
Damage level
*3-story
*Moderate
*R/C with Brick Infill Walls
*E0=0.15 to 0.20
according to Japanese standard
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Comparisons between collapsed/moderately damaged buildings
Smaller
Damage level
*Collapse
Amount of Brick Infill?
Why?
Larger
Damage level
*Moderate
Conclusion
Brick Infill contributed to the seismic
performance of buildings
Experimental Approach
Preparation of R/C frame specimen
Upper beam
700
2 x 40%-scale R/C one-bay
frame specimens,
a'
550
D10
12-D19
2,150
1,000
4-φ9
φ4@100
b
b'
600
D10
12-D19
800
700
a
2,250
300
a-a'
121
Lower beam
4-φ9
100
800
140
325
140
b-b'
φ4@100
representing 1st-story of the
surviving building
Experimental Approach
Preparation of R/C frame specimen
Uppre beam
700
700
Upper beam
a'
a'
550
550
D10
12-D19
Brick Wall 140mm
φ4@100
b
Brick
wall
Mortar20mm
2,150
1,000
2,150
1,000
4-φ9
b'
600
600
D10
12-D19
300
a-a'
121
Lower beam
325
4-φ9
140
b-b'
φ4@100
800
2,250
800
a
700
800
700
a
2,250
100
800
140
325
Lower beam
300
a-a'
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
Preparation of brick wall specimen
Cutting from moderately
damaged building
Transported
Infill
Transporting to
Toyohashi Univ.
Seismic
Testing
Experimental Approach
Test set-up and loading program
Test set-up
West
East
Negative Positive
400
2000 kN Vertical jacks
1750
Steel Box
450
West
East
Steel Box
Loading program
– Vertical loading: Constant (183.4 kN)
– Horizontal loading: Cyclic (1/8001/12.5)
1000 kN Horizontal jack
Experimental Approach
Lateral force vs. drift ratio
R/C Bare Frame
Lateral Force(kN)
200
Infilled Frame
BF
100
Qmax = 36.75 kN
0
-100
Qmin = -34.5 kN
柱の曲げひび割れ
-200
-2
-1
0
1
Drift Ration (%)
2
Experimental Approach
Lateral force vs. drift ratio
R/C Bare Frame
200
Infilled Frame
200
BF
Qmax = 163.5 kN
IF
100
Qmax = 36.75 kN
0
-100
Qmin = -34.5 kN
Lateral Force (kN)
Lateral Force(kN)
×
100
▲
0
柱、壁の分離
柱の曲げひび割れ
-100
△
△ 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
柱の曲げひび割れ
-200
-2
-1
0
1
Drift Ration (%)
2
-200
Qmin = -174 kN
-2
-1
0
1
Drift Ration (%)
2
Experimental Approach
Comparison of performance curves
200
Lateral force (kN)
150
100
50
0
-50
QBF=28.5kN
-100
-150
-200
-10
QIF=174.0kN
-7.5
-5
1.6% 2.8%
-2.5
0
2.5
Drift ratio (%)
5
7.5
10
Test and Analysis of a Masonry Infill Wall
Used in Indonesia
at Tongji Univ. in Sep. 2011
Yasushi SANADA, Toyohashi Univ. of Tech., Japan
Damage level
*Collapse
Damage level
*Moderate
Conclusion
Brick Infill contributed to the seismic
performance of buildings
Simple strut model for evaluating infill-frame interaction
Yasushi SANADA, Osaka Univ., Japan
Introduction
dm
Strut Model
h
H

Strut width w:
W  0.175 h
0.4
where

Em t sin 2 
(Stafford-Smith and Carter)
4 Ec I g hm
W = 0.25 dm (Paulay and Priestley)
W
1 -  c  c h
cos 
αc : the ratio of the column contact length to the
height of the column (El-Dakhakhni et al.)
Modeling of Infilled Frame
Q
Infilled frame
Contribution of infill to
strength/stiffness
Column
deformation: cδ
Infill
deformation : iδ
Flexural
deformation
Shear
deformation
Strut width (W) = ?
Infilled frame
deformation
Frame/Infill
contact length
y: intersection point
iδ = cδ
Evaluation of cδ
Q
Q
w
h
Moment
diagram
h
2
EI
L
Column
Displacement: cδ(y)
d x
Double

M
(
y
)
Integration
dy 2
EI x   ( y)
Equivalent
stress block
f m
Q
f ' m=
Qu
fm
Mu
hs
y
Cs
hs
w
Ch
hs
Cs
h
θ
fm
cδ
f’m = 0.65 fm
L
Column displacement:
0 ≤ y ≤ hs.

1
2
3
4



y

1
/
2
.
M
.
y

1
/
6
.
Q
.
y

1
/
24
.
C
.
y
c
u
u
h
Ec I c

Evaluation of cδ
Q
θ=0
cδ
h
Ch
hs
Mu
Qu
hs
y
Moment
diagram
Column
Displacement: cδ(y)
d 2x
EI 2  M ( y ) Double
Integration
dy
Column displacement:
hs ≤ y ≤ h :
c   y
EI x   ( y)


1
2
(1 / 6. Qu  Ch . h. y 3  1 / 2. M u 1 / 4. Ch . hs . y 2
Ec I c
1 / 6 Ch .hs . y 1 / 24. Ch . hs )
3
4
Evaluation of iδ
i
 y  i y
iδ
Infill : uniform shear deformation
i

c
  y  h
h
θ
θ
Infill/Frame Contact Length
Finding intersection height
c
 y  i y
(Newton Raphson Method)
hs
hs : intersection height
hs: Infill/frame contact length
w=
hs cos θ
Infill/Frame Contact Length
Finding intersection height
c
 y  i y
(Newton Raphson Method)
hs : intersection height
hs: Infill/frame contact length
w = 2 hs cos θ
Application to Test Specimen
Lateral force vs. drift ratio
R/C Bare Frame
200
Infilled Frame
200
BF
Qmax = 163.5 kN
IF
100
Qmax = 36.75 kN
0
-100
Qmin = -34.5 kN
Lateral Force (kN)
Lateral Force(kN)
×
100
▲
0
柱、壁の分離
柱の曲げひび割れ
-100
△
△ 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
柱の曲げひび割れ
-200
-2
-1
0
1
Drift Ration (%)
2
-200
Qmin = -174 kN
-2
-1
0
1
Drift Ration (%)
2
Evaluation of Infill Contribution
Lateral force at the same drift ratio
200
200
Qmax = 163.5 kN
IF
IF_FB
200
BF
▲
0
柱、壁の分離
柱の曲げひび割れ
-100
△
△ 壁のせん断ひび割れ
100
Qmax = 36.75 kN
0
-100
Qmin = -34.5 kN
Lateral force (kN)
100
Lateral Force(kN)
Lateral Force (kN)
×
100
0
-100
柱のせん断ひび割れ
主筋の降伏
-200
▲ 帯筋の降伏
× 柱のせん断破壊
Qmin = -174 kN
-2
-1
0
1
Drift Ration (%)
柱の曲げひび割れ
2
-200
-2
-1
0
1
Drift Ration (%)
2
Experiment
-200
-2
-1
0
Drift ratio (%)
1
2
Verification of Analytical Model
Analysis
Experiment
hs = y
Lateral force (kN)
200
100
0
-100
-200
-2
-1
0
1
Drift ratio (%)
Contact length:
Lateral strength of infill:
hs= 312 mm
Q  w. t. f m . cos 
Strut width :
w = 2 hs cos
= 515 mm
= 112.6 kN
Initial lateral stiffness of infill:
K 
Em . w. t
cos 2 
d
2
Seismic Performance of Infilled R/C Frame
Q
Qt
Cs
h
Qt
Cs/2 cos θ
Qu
Ch
Qu
hs
300
Q  Qu  Cs / 2 cos   Qt
200
Lateral force (kN)
Lateral strength of
overall infilled frame:
100
0
-100
Test
Model
-200
-300
-4
-2
0
Drift ratio (%)
2
4
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