seismic performance evaluation of existing rc buildings in
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SEISMIC PERFORMANCE EVALUATION OF EXISTING
REINFORCED CONCRETE BUILDINGS IN YANGON
Phyo Hein Kyaw
1
OUTLINE OF THE PRESENTATION
Introduction
Objective of the Study
Scope
Procedure
Case Studies
Results and Discussion
Conclusion
2
INTRODUCTION
Yangon, the commercial city of Myanmar, is the biggest city in Myanmar and
located near the Sagaing fault .
Over the past three decades, many frequent earthquakes with various
intensities occurred there.
In Yangon, there are two popular types of building, reinforced concrete type for
residential and masonry type for public use mostly.
3
• Most of the reinforced concrete buildings less than 8 floors in Yangon were designed
only by gravity based design.
• According to the current situation, for these low rise and mid rise buildings, seismic
design is not considered for both old and new ones.
PROBLEM STATEMENT
4
• This study is aimed to find the performance of the low to mid rise R.C
buildings in Yangon under different earthquake levels.
OBJECTIVE OF THE STUDY
5
• To analyse the R.C buildings ( three story , six story and eight story)in
two townships of Yangon
• To find the performance of each building
• To develop the fragility curve for three earthquake levels (MOE, DBE
and MCE)
SCOPE OF THE STUDY
6
Collect Data Assessment of the Building
consistency to Gravity-based Design
Determine Evaluation
Requirements
Modelling
Seismic Evaluation
DeficienciesYesNo
Analysis
(Linear Static
Procedure)
Further
Evaluation
No
No
Yes
Yes
No
Building
CompliesFinal Evaluation Result
Yes
Analysis
(Non-Linear Static
Procedure)
Target
Performance
Level
Building
Does
NOT
Complies
FLOW CHART FOR THE STUDY
Fragility Curve
End
Start
7
CODE AND REFERENCE FOR ANALYSIS
MNBC
ASCE 7-10
ATC-40, FEMA 356
SDS=(2/3)FaSS=(2/3) x 1.176 x 0.77 = 0.604
SD1=(2/3)FvS1=(2/3) x 2.76 x 0.31 = 0.57
Fv= 2.76
Fa= 1.176
8
STRUCTURE PERFORMANCE
9
Under MOE Under DBE Under MCE
PERFORMANCE OBJECTIVE
Type Structural Performance Level
Immediate Occupancy(IO) Life Safety (LS) Collapse Prevention (CP)
Drift 1% transient;
negligible permanent
2% transient;
1% permanent
4% transient
or permanent
10
Fragility curve is a statistical tool representing the probability of exceeding a
damage limit state for a given structure type subjected to a seismic excitation
(shinozuka et al, 1999).
Probability of failure, Pf= P [Z < 0| EQ ]
FRAGILITY CURVE
u2
u2
maxcr
cr
uu
Pf = 1 - Φ
Z = Capacity - Demand
11
SOIL PROFILE TYPE COMPUTATION
Soil
Type
Shear wave
velocity (vs)
SPT(N)
A vs>5000ft/s -
B 2500ft/s<vs<5000ft/s -
C 1200ft/s<vs<2500ft/s N>50
D 600ft/s<vs<1200ft/s 15<N<50
E vs<600ft/s N<15
ASCE-7-10, ASCE-41-13
n
ii
i
s
N
dd
N
1
For BH 1
Depth(ft) SPT(Ni) di ∑(di / Ni)
07 6 0.86
6
610 3 0.30
9
911 3 0.27
12
1213 6 0.46
18
187 6 0.86
24
246 6 1.00
30
309 10 1.11
40
409 10 1.11
50
SUM 5.97
For BH 2
Depth(ft) SPT(Ni) di ∑(di / Ni)
06 6 1.00
6
69 3 0.33
9
911 3 0.27
12
1214 6 0.43
18
188 6 0.75
24
247 6 0.86
30
308 10 1.25
40
4010 10 1.00
50
SUM 5.89
Item Street Township
Avg
SPT(N)
Soil
Type
1 50th Street Pazundaung 6.43 E
2 Kaung Yan Street Pazundaung 8.56 E
3
Lower Pazundaung
Street Pazundaung 8.47 E
4 51st Street Pazundaung 8.43 E
5 Yay Kyaw Street Pazundaung 8.15 E
6 Thar Yar Kone Street Pazundaung 11.13 E
*Soil Investigation Report is from 51st street, Pazundaung.
Pazundaung Township
Item Street Township
Avg
SPT(N)
Soil
Type
1 156th Street Tarmwe 5.67 E
2 Bayatheikti Street Tarmwe 10.58 E
3 Thiri Street Tarmwe 14.52 E
4 Ar Yoe Gone Street Tarmwe 10 E
5 Ponenar Kone Street Tarmwe 9 E
6 Myo Thit (2) Street Tarmwe 7.78 E
Tarmway Township
12
MATERIAL STRENGTH DETERMINATION
Concrete Strength (fcu)
Building
Type
Constructed Number of Story fcu(Mpa)
R.C Before 2000 3 Story, 4 Story 25.5
R.C Before 2005 3, 6 and 8 Story 28.5
R.C Around 2010 3 , 5 and 8-1/2 Story 33
Reinforcing Steel (fy, fu)
As per as-built design drawing and documentation
Consistency check with Rebar locator
13
CASE STUDY R.C BUILDINGS
Item Story Type Township Quantity
1 3 Story A Tarmway 1
2 6 Story B Tarmway 1
3 8 Story C Pazundaung 1
14
BUILDING-A
Typical Story Height 9.5ft
Bottom Story Height 10ft
Total Height 34ft
Soil Profile Type SE
Building Aspect Ratio 2.22 (27’ x 60’)
Plan Configuration Asymetric
f’c 3000psi
fy 40000psi3D View Plan View
15
BUILDING-B
3D ViewPlan View
Typical Story Height 10ft
Bottom Story Height 12ft
Total Height 68ft
Soil Profile Type SE
Building Aspect Ratio 2 (25’ x 50’)
Plan Configuration Asymmetric
f’c 3000psi
fy 40000psi
16
BUILDING-C
3D ViewPlan View
Typical Story Height 10.5ft
Bottom Story Height 12ft
Total Height 89ft
Soil Profile Type SE
Building Aspect Ratio 1.76 (34’ x 60’)
Plan Configuration Symmetric
f’c 3000psi
fy 40000psi
17
DAMAGE ASSESSMENT
(BUILDING-A)
0
20
40
60
80
100
120
0 0.5 1 1.5 2
Pro
ba
bil
ity
of
Fa
ilu
re
(%)
Sa(g)
Fragility Curve
MOE
DBE
MCE
RESULTS AND DISCUSSION
18
0
20
40
60
80
100
120
0 0.5 1 1.5 2
Pro
ba
bil
ity
of
Fa
ilu
re
(%)
Sa(g)
Fragility Curve
MOE
DBE
MCE
DAMAGE ASSESSMENT
(BUILDING-B)
RESULTS AND DISCUSSION
19
0
20
40
60
80
100
120
0 0.5 1 1.5 2
Pro
ba
bil
ity
of
Fa
ilu
re
(%)
Sa(g)
Fragility Curve
MOE
DBE
MCE
DAMAGE ASSESSMENT
(BUILDING-C)
RESULTS AND DISCUSSION
20
CONCLUSION
From this study, the selected R.C buildings are in moderate performance in seismic
condition.
for DBE level earthquake, 3 story building can be damaged about one fourth of the
total building members and about almost all can be damaged under MCE level
earthquake. The 6 story building can have about 25% damage for life safety level
earthquake and more than 80% probability of failure under severe earthquake.
And also, the 8 story building has damages of more than a quarter of the total under
moderate earthquake (DBE) and nearly 95% probability to be damaged under MCE
earthquake. Therefore, it can be clearly seen that the existing R.C buildings cannot
withstand for severe level earthquake.
Thus retrofit and strengthening is required for severe earthquake levels in these
existing buildings.
21
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