vulnerability assessment of kathmandu valley and ......vulnerability assessment of kathmandu valley...
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Vulnerability Assessment of Kathmandu Valley
and Surrounding Areas
based on Comprehensive Damage Investigation
of the 2015 Gurkha, Nepal Earthquake
Kimiro Meguro, Director/Professor,
International Center for Urban Safety Engineering,
Institute of Industrial Science (IIS), The University of Tokyo (Utokyo)
Ramesh Guragain, Deputy Executive Director,
National Society for Earthquake Technology-Nepal (NSET)
Project team members
Name Affiliation
Dr. Kimiro Meguro (PI) Director/Professor, ICUS, IIS, UTokyo
Dr. Muneyoshi Numada Lecturer, ICUS, IIS, UTokyo
Dr. Hideomi Gokon Asst. Prof., ICUS, IIS, UTokyo
Dr. Osamu Murao Professor, IRIDeS, Tohoku University
Dr. Shunichi Koshimura Professor, IRIDeS, Tohoku University
Dr. Erick Mas Asst. Prof., IRIDeS, Tohoku University
Mr. Kenjiro Yamamoto PhD candidate, Utokyo
Ms. Natsumi Hara Graduate student, Chuo University
Mr. Kazuma Hasekura Graduate student, Chuo University
Name Affiliation
Dr. R. Guragain Deputy Executive Director, NSET
Mr. G. K. Jimee Director, NSET
Mr. H. Shrestha Director, NSET 1
Objective of the Study
� To support the reconstruction activities and retrofitting the
buildings affected by the 2015 Nepal-Gurkha Earthquake,
based on the distribution of building damage, ground
condition and expected distribution of seismic intensity.
2
Study area
� Kathmandu Valley and its surrounding areas.
Framework
• Efficient and effective activities for recovery and reconstruction.
• Identification of the areas and buildings where the retrofitting
should be applied preferentially.
Remote sensing
(UAV, Satellite)
Distribution of
building damage
Developing fragility function by simulation
Distribution of PGA
Propose the appropriate method for retrofitting3
Damage probability of several types of structures
Fragility curve
Expected Outcomes
1. Acquisition of spatial information data of buildings in widespread area
2. Acquisition of extensive building damage data and understanding of actual condition
3. Development of high-precision fragility curve for Nepalese buildings
4. Micro-zoning for efficient recovery and reconstruction of affected areas
5. Clarification of areas and buildings to be strengthened preferentially to reduce thedamage by future earthquakes
6. Proposal of proper seismic retrofit methods for vulnerable buildings in Nepal
4
1. Acquisition of spatial information data
of buildings in widespread area
Open Street Map
Satellite imageBuilding location were
identified using Open Street
Map and visual interpretation
of satellite images, and UAV.
UAV
Aerial photos (UAV :
http://www.dji.com/pr
oduct/phantom)
5
2. Acquisition of building data and identification of the building damage
Field Survey
Visual inspectionDamage
probability
7
Complete damageExtensive damage
Others
3. Development of high-precision
fragility curve for Nepalese buildings
This part is presented by Dr. Guragain.
8
9
Guidance and Utilizing the Facility from Utokyo (ICUS, IIS), Solving the Problem of Nepal
Collaborative Work between
NSET and The University Tokyo
Comparison of Work done before Earthquake
with Findings after Earthquake
In-situ Measurement of Masonry Mortar Joint Shear
Strength: Process Test as per ASTM C1531 – 09
10Start with Understanding Key Parameters
11
Masonry Mortar Joint Shear Strength: Mud Mortar
12
8
14
9
11
6
4
2
0
2
4
6
8
10
12
14
16
<0.02 0.02-0.04 0.04-0.06 0.06-0.08 0.08-0.1 0.1-0.12 >0.14
Nu
mb
er o
f Tes
ts (
Nu
mb
er)
Shear Strength (MPa)
Simulation using AEM
Simulation of Experimental Model
• Simplified
• Roof weight on top layer wooden elements
Experimental Verification
13
(Sakthiparan, 2008)
Result Comparison (Run 37: 20Hz, 0.8g)
14
Result Comparison (Run 45: 5Hz, 0.6g)
15
Analysis of Brick in Cement Buildings with Flexible Floor and Roof
16
BC1BC2
BC3
BC4 BC5
BC6
BC7BC8
•8 Buildings
•3 Mortar types•STRONG, Average, Weak
•5 Time Histories
17
Taplejung Earthquake, Nepal
Chi Chi Earthquake
Koceli Earthquake
Kobe Earthquake
Loma Prieta Earthquake
Strong ground motions used
for developing fragility curves
18
Koceli Earthquake 0.2 g Max Amplitude
(One of the Strongest Case)
0.15g: Slight Damage
0.25g: Moderate Damage
0.6g: Extensive Damage
0.65g: Complete
19
0.25g: Extensive Damage
0.35g: Complete Damage
Average Strength Mortar, Koceli Earthquake
20
N: Negligible; S: Slight Damage; M: Moderate Damage; E: Extensive Damage; C: Complete Damage
Building
Acceleration (g)
0.05 0.10.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7
BC1-Strong-Loma N N S M M M M E E E C C C CBC1-Avg-Nep N N S M M E E E C C C C C CBC1-Avg-chi N S M M M E E E C C C C C C
BC1-Avg-Koce N S M M E E E C C C C C C CBC1-Weak-Kobe N M M E E C C C C C C C C C
BC2-Strong-Loma S S M M E E C C C C C C C CBC2-Avg-Nep S M M E E C C C C C C C C CBC2-Avg-Chi S M M E E C C C C C C C C C
BC2-Avg-Koce M M M E C C C C C C C C C CBC2-Weak-Kobe E E C C C C C C C C C C C CBC3-Str-Loma N N N S S M M M E E E E C CBC3-Avg-Nep N S S M M E E E C C C C C CBC3-Avg-chi N S S M M E E C C C C C C C
BC3-Avg-Koce N S S M E E E C C C C C C CBC3-Weak-Kobe S M M E E C C C C C C C C C
BC4-Str-Koce N N S S M M M E E E E C C CBC4-Avg-Nep N S M M E E E C C C C C C CBC4-Avg-Chi N S M M E E E C C C C C C C
BC4-Avg-Koce N S M E E E C C C C C C C CBC4-Weak-Kobe S M M E E C C C C C C C C C
Continue………..
Different level of Damages at Different Acceleration
21
Damage Level
Number of Cases at Different PGA (%g)0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7
None 14 2 0 0 0 0 0 0 0 0 0 0 0 0Slight 9 15 5 0 0 0 0 0 0 0 0 0 0 0
Moderate 1 7 17 14 7 0 0 0 0 0 0 0 0 0Extensive 0 0 2 10 16 17 14 9 5 2 0 0 0 0
Complete 0 0 0 0 1 7 10 15 19 22 24 24 24 24
Damage Level
Cumulative Probability of Damage at Different PGA (%g)0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7
Slight 0.04 0.29 0.79 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00Moderate 0.00 0.00 0.08 0.42 0.71 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00Extensive 0.00 0.00 0.00 0.00 0.04 0.29 0.42 0.63 0.79 0.92 1.00 1.00 1.00 1.00Complete 0.42 0.92 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
22
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Pro
ba
bil
ity
[d
s/P
GA
]
Peak Groung Acceleration PGA (g)
Case 1: Slight
Case 1: Moderate
Case 1: extensive
Case 1: Complete
Case 2: Slight
Case 2: Moderate
Case 2: Extensive
Case 2: Complete
Fragility Function for Brick in Cement
Buildings in Nepal with Flexible Floor/Roof
23
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Pro
ba
bil
ity
[d
s/P
GA
]
Peak Groung Acceleration PGA (g)
Case 1: Slight
Case 1: Moderate
Case 1: extensive
Case 1: Complete
Case 2: Slight
Case 2: Moderate
Case 2: Extensive
Case 2: Complete
Fragility Functions for Brick in Mud Buildings in Nepal
with Flexible Floor/Roof
Different Models Prepared and Different level of
Damages at Different Acceleration Noted
0.45g, Extensive
0.55g, Complete
0.3g, Extensive
0.4g, Complete
0.2g, Extensive
0.3g, Complete
Damage probability at different level of acceleration
25
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Pro
ba
bil
ity
[d
s/P
GA
]
Peak Groung Acceleration PGA (g)
Case 1: Slight
Case 1: Moderate
Case 1: extensive
Case 1: Complete
Case 2: Slight
Case 2: Moderate
Case 2: Extensive
Case 2: Complete
Stone Masonry Modeling: New Approach
1. Randomly Generated
Triangles2. Clustering certain number of nearby
triangles
Stone properties inside the cluster
Mortar properties in the boundary
Stone properties inside the cluster
Mortar properties in the boundary
3. Assigning stone and mortar properties
26
Fixed in all 3-displacements and 3-Rotations
Z-displacement Free, Other degrees of freedom fixed
Fixed in all 3-displacements and 3-Rotations
Z-displacement Free, Other degrees of freedom fixed
1st Model: 1:4 Scale Stone Masonry Wallet
Experimental ModelNumerical Model
Materials TensileStrength(MPa)
CompressiveStrength(MPa)
Young'sModulus(GPa)
FrictionCoefficient
Mortar 0.078 8 0.4 0.6Stone 100 1000 3 0.6
m
th
s
th
M
th
E
m
E
S
E
M +=
Mth, EM: Thickness and Young’s
Modulus for Masonry
Sth, Es: Thickness and Young’s
Modulus for Stone
mth, Em: Thickness and Young’s
Modulus for Mortar
27
Crack patterns
Crack pattern at 3 mm vertical displacement
from experiment (Sakurai, K., 2011)
Crack pattern at 3 mm vertical
displacement from Numerical Simulation
28
Force Displacement Comparison
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6
Displacement (mm)
For
ce (
KN
)ExperimentNumerical
29
Shaking Table Test Verification
30
(Sakurai, K., 2011)
Crack patterns: (after Run 40, 15Hz, 0.8g)
31
Crack patterns: (after Run 48, 5Hz, 1.0g)
32
Stone Masonry Buildings
33
SM1
SM2
SM3
SM4
SM5
SM6
Damage State at each PGA Noted
34
0.1g, Koceli, Extensive
0.15g, Koceli, Complete
0.25g, Koceli, Extensive
0.35g, Koceli, Complete
Average
Mortar
35
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6
Pro
ba
bil
ity
[d
s/P
GA
]
Peak Groung Acceleration PGA (g)
Case 1: Slight
Case 1: Moderate
Case 1: extensive
Case 1: Complete
Case 2: Slight
Case 2: Moderate
Case 2: Extensive
Case 2: Complete
Fragility Functions for Stone in Mud Buildings in Nepal with Flexible Floor/Roof
36
Comparison of Response Spectra with The Ground Motions Used Earlier with
Gorkha Earthquake
Simulation with Gorkha Earthquake Ground Motion
37
SM1
SM2
SM3
SM4
SM5
SM6
Connecting the Computer at The University of Tokyo from Nepal
38
0.15g, Koceli 0.35g, Koceli
Average
Mortar
0.2g, Gorkha
0.4g, Gorkha
39
Comparison of Fragility FunctionsFive Time Histories and Gorkha Earthquake
40
Simulation of Brick Buildings for Code Implementation
Slight
Damage
Moderate
Damage
Extensive
DamageComplete
Damage
0.1 g 0.15 g 0.25 g 0.35 g
0.4 g 0.6 g 0.8 g1 .0g
With Cement Mortar Single Vertical Bar Enhance Capacity from 0.8g to 1.0 gKoceli
Average
41
Gorkha Earthquake 0.3g Gorkha Earthquake 0.5g
Research for Reconstruction
Model without Earthquake
Resistant ElementsModel with Earthquake
Resistant Elements
Average Mortar
Conclusions
– Numerical Simulation of Some Buildings with
Building Code Implementation conducted and can be
compared with the developed fragility functions
42
• Fragility Functions Developed Earlier are Compared with
Fragility Functions Developed using Gorkha Earthquake Ground
Motions
• Damage by Gorkha Earthquake is Less by about 0.05g in
Average with the Average Damage by 5 Earthquake Ground
Motions Used Earlier
4. Micro-zoning for efficient recovery
and reconstruction of affected areas
43
44
Study Area
1
2
3
4
5
A B C D E F
D E F G H
Study area of evaluation
of damage
Among all seasons, there is snow and the number of houses is very limited.
Out of
study area
Pick up 36 settlements (50 to 1,228 buildings per settlement) in 32 blocks, and evaluate damage levels.
45
Distribution of Settlements and their major type of structures
Micro-zoning for efficient recovery and reconstruction of affected areas
Damage probability of typical structures in each settlement
Kathmandu
Fragility function developed
by Dr. Remesh Guragain
Damage Probability � Peak Ground Acceleration (g)
• BCr : Brick in Cement Buildings with Rigid Floor/Roof
• BCf : Brick in Cement Buildings with Flexible Floor/Roof
• BMf : Brick in Mud Buildings with Flexible Floor/Roof
• SMf : Stone in Mud Buildings with Flexible Floor/Roof
47
Micro-zoning for efficient recovery and reconstruction of affected areas
Distribution of PGA (gal)
A distribution of PGA was estimated by the interpolation of PGA point.48
5. Clarification of areas and buildings
to be strengthened preferentially
against high-risk future earthquakes
49
Clarification of areas and buildings to be strengthened
preferentially against high-risk future earthquakes
Distribution of PGA
Fragility curves
Distribution of damage probability
Clarification of areas and buildings to
be strengthened preferentially
50
• BCr : Brick in Cement Buildings with Rigid Floor/Roof
• BCf : Brick in Cement Buildings with Flexible Floor/Roof
• BMf : Brick in Mud Buildings with Flexible Floor/Roof
• SMf : Stone in Mud Buildings with Flexible Floor/Roof
Damage probability of each type of structureBCr (Brick in Cement with Rigid Floor/Roof)BCf (Brick in Cement with Flexible Floor/Roof)
BMf (Brick in Mud with Flexible Floor/Roof) SMf (Stone in Mud with Flexible Floor/Roof)
)
51
Comparison
BCr
(complete)
SMf
(complete)
Identify the vulnerable zone
52
• According to fragility curve, Brick in Cement Buildings with Rigid Floor/Roof (BCr) is the strongest, and Stone in Mud Buildings with Flexible Floor/Roof (SMf) is the weakest among these structures
• Next step is to compare the damage probability map from several types of structures with BCr.
Subtract Pd(BCr) from Pd(BMf)
53
Pd(BCr)- Pd(BMf)
Brick in Mud
structures with
Flexible Floor/Roof
located in the area
should be retrofitted
Subtract Pd(BCr) from Pd(BMf)
54
Pd(BCr)- Pd(BMf)
Subtract Pd(BCr) from Pd(SMf)
55
Pd(BCr)- Pd(SMf)
Subtract Pd(BCr) from Pd(SMf)
56
Pd(BCr)- Pd(SMf)
Stone in Mud
structures with
Flexible Floor/Roof
located in the area
should be retrofitted
6. Proposal of proper seismic retrofit
method for vulnerable buildings in Nepal
57
1) Unreinforced Masonry Common Residential Buildings:
→ PP-Band Method (PPM)
2) Unreinforced Masonry School Buildings:
→ Splint and Bandage + PP-band Method(SB-PPM)
3) Low or Middle Rise Reinforced Concrete Buildings:
→Modified Reinforced Concrete Masonry Infill
(MRCMI)
58
Retrofitted adobe masonry house (2009)
2-story adobe mud mortar house
(weakest type structure)
Due to lack of power and welders, cross points of PP-bands were not welded. Just weave PP-bands in wave form without connecting at cross points.
Totally collapsed adobe masonry house
Mud mortar adobe house is really vulnerable to earthquake.
Retrofitted adobe house after the quake (2015)
Retrofitted adobe house after the quake (2015)
Spalling of surface finishing
mud mortal. This is an evidence
of the effects of PP-band method.
62
Earthquake Safety School Project by NSET
Before the 2015 Gurkha Earthquake,
NSET has retrofitted about 200 school buildings by Full
Wall Jacketing method (FWJM) and Splint and Bandage
method (SBM). There was no damage to these
retrofitted structures except 4 buildings have fine
cracks. All of these retrofitted school buildings could be
used as shelters for affected people.
While about 300 school buildings were severely
damaged or collapsed. In all affected area by the
Gurkha 2015, about 6,000 school buildings were
severely damaged or collapsed.
63
Un-retrofitted oneRetrofitted ones
Inside of classroom
Inside of retrofitted school. It is used as shelter for affected peopleNo damage to the structure
that NSET retrofitted.
Earthquake Safety School Project by NSET
School buildings after the eq.
64
Splint and Bandage Method
Full Wall Jacketing Method (better but expensive)
Methods that NSET has adopted
65
Recommended Method for School building
2) Splint and Bandage Method(SBM):relatively inexpensive.
Set RC horizontal and vertical bands at critical locations but in case of severe shaking, URM wall may collapse and attack people.
1) Full Wall Jacketing Method(FWJM): Efficient but expensive
3) Splint and Bandage + PP-band Method (SB-PPM):URM wall is retrofitted by PP-band method to prevent collapse of wall and save people. Additional cost is very small.
Model retrofitted by SBM
Model retrofitted by SB+PPM
66
Concrete Beam and Column
MasonryPolystyrene Foam
Mortar PP Band
RCMI
Recommended method for low and middle rise building
(Modified Reinforced Concrete Masonry Infill)
MRCMI
Validation of Numerical Model(AEM)
67
0
20
40
60
80
100
120
140
0 0.002 0.004 0.006 0.008 0.01
Forc
e (
KN
)
Displacement (m)
Force vs Displacement
Experimental AnalyticalAEM Simulation
Failure Behavior
of Frame Structure
68
920
800
75
100
120
50
680
120 1160 20
50
25
2040120
680
Concrete Strength: 20 MPaYoung’s Modulus: 2.49e+10MPa
Masonry:Compressive Strength: 15 MPaInitial Stiffness: 1.35e+10MPa
Engineered FrameNon-Engineered
Frame
Comparison of Engineered and Non-engineered RC frame
69
Collapse analysis of full scale 3D infilled frame
Bare NE_RC Frame
NE_RCMIFrame NE_MRCMI
Frame
NE_MRCMI Frame
with PP-Band
• 2 Storey, S. Width = 3.3 m, S. Height = 4 m
Building 1 Building 2 Building 3 Building 4
70
Building 1
1 2
3 4
Kocaeli earthquake
71
Building 2
1 2
3 4
72
Building 3
1 2
3 4
73
Building 4
1
2
3
Summary
1. Acquisition of spatial information data of buildings in widespread area � O.K
2. Acquisition of extensive building damage data and understanding of actual condition � Could not be obtained all the damage data, therefore we interpolated the building damage data in 36 settlements.
3. Development of high-precision fragility curve for Nepalese buildings � O.K
4. Micro-zoning for efficient recovery and reconstruction of affected areas � O.K
5. Clarification of areas and buildings to be strengthened preferentially against high-risk future earthquakes � O.K
6. Proposal of proper seismic retrofit method for vulnerable buildings in Nepal� O.K
74