Seismic vulnerability assessment of Residential Buildings in Agartala City using Rapid Visual Screening Method

1. SEISMIC VULNERABILITY ASSESSMENT OF RESIDENTIAL BUILDINGS IN
AGARTALA CITY USING RAPID VISUAL SCREENING METHOD
PRESENTED BY
PROJECT GROUP
B. TECH 8TH SEMESTER
Under the Guidance of
Asstt. Prof. LIPIKA HALDER
Department of Civil Engineering
NIT, AGARTALA

2. CONTENT
• Introduction
• Objectives of the study
• Methodology
• DETAILS OF CASE STUDIES
• Results and Discussions
• CONCLUSIONS
• FUTURE SCOPE OF THE STUDY
• References
2

3. INTRODUCTION
• Earthquakes are one of the most devastating
forces in nature. These have been instrumental in
changing the courses of Indian history.
• Some of the most significant disasters in the last
hundred years caused by earthquake results a loss of
about 2,03141 human lives, besides damage to
property and infrastructure.
• Around 60% of the country’s landmass is prone to
moderate, high or severe earthquake risks. North-
east experiences earthquake of average magnitude
>6.0 every year which causes huge losses to
property. 3

4. • As Tripura, north-eastern state of India is situated
in seismic zone V which is severe most zone
indicated by the Indian Seismic code IS 1893(Part
1)2002. So this study proposes an approach to
estimate the seismic vulnerability assessment of
residential buildings in Agartala city.
4

5. Seismic Zones IS 1893(Part 1):2002
5

6. OBJECTIVES OF THE STUDY
• To assess the seismic vulnerability of residential
buildings in Agartala city using Rapid Visual
Screening Method proposed by FEMA 154 (2015)
• To predict the expected damage grade that may be
observed in the surveyed buildings in future severe
earthquake.
6

7. METHODOLOGY
1.Rapid visual screening (RVS) procedure requiring only visual
evaluation and limited additional information (Level 1
procedure). This procedure is recommended for all buildings.
2. Simplified vulnerability assessment (SVA) procedure requiring
limited engineering analysis based on information from visual
observations and structural drawings or on-site measurements
(Level 2 procedure). This procedure is recommended for all
buildings with high concentration of people.
3. Detailed vulnerability assessment (DVA) procedure requiring
detailed computer analysis, similar to or more complex than
that required for design of a new building (Level 3 procedure).
This procedure is recommended for all important and lifeline
buildings
7

8. RAPID VISUAL SCREENING PROCEDURE
(RVS)
• Rapid visual screening was first proposed in US in
1988 in the FEMA 154 report, which was latest
modified in 2015 to incorporate latest technological
advancements and lessons from earthquake disasters
in the 1990.
• RVS is useful when the number of buildings to be
evaluated is large.
8

9. SURVEY PARAMETERS
 General Information: Type of building, Number of
stories, Year of construction, Number of occupants,
Maintenance record.
 Structural Irregularities: Vertical irregularities, Plan
irregularities.
 Apparent building quality: Quality of materials &
construction.
 Soil conditions.
 Frame action
 Diaphragm action.
 Heavy overhangs, Soft story, Short column.
9

10.  Pounding effect: Two Adjacent buildings.
 Openings: Large openings in wall, irregular openings
in walls.
 Bands: Horizontal Bands at plinth level, lintel level,
sill & roof level.
 Falling Hazards.
 Wall thickness at ground floor.
 Water tank at roof: Capacity and location.
10

11. DETAILS OF CASE STUDIES
 The side walk survey was conducted in a phased
manner between 25 August,2016 to 4th April ,2017.
 The road no’s are respectively –
7,8,9,10,13,14,15,16 and 17, which was surveyed
during this period.
 Total 350 no’s of residential buildings are surveyed.
Among them 205 comprise RCC structures, 116
comprise masonry constructions, 29 are Composite
structures and the remaining is mixed type
 A performance score is calculated for each building
which indicates whether the building strength is
adequate to withstand earthquake forces
11

12. 12

13. Rapid Visual Survey for Masonry buildings
13

14. 14

15. Rapid Visual Survey for RCC buildings
15

16. 16

17. Predicted damage grades
17
RVS Score Damage Potential
S < 0.4 High probability of Grade 5 damage; Very high probability of Grade 4
damage
0.4 ≤ S ≤ 0.9 High probability of Grade 4 damage; Very high probability of Grade 3
damage
1.0 ≤ S ≤ 1.5 High probability of Grade 3 damage; Very high probability of Grade 2
damage
1.6 ≤ S ≤ 2.0 High probability of Grade 2 damage; Very high probability of Grade 1
damage
2.0 < S Probability of Grade 1 damage

18. 18
DAMAGE GRADE MASONRY BUILDINGS R.C.C STRUCTURES
Grade 1
Negligible to slight damage
(No structural damage, slight non-
structural damage)
1. Hair-line cracks in very few walls.
2. Fall of small pieces of plaster only.
3. Falling of loose stones.
1. Fine cracks in plaster over frame members or
in walls at the base.
2. Fine cracks in partitions and infill's.
Grade 2
Moderate damage
(Slight structural damage, moderate
non-structural damage)
1. Cracks in many walls.
2. Fall of fairly large pieces of plaster.
3. Partial collapse of chimneys.
1. Cracks in columns and beams of frames and
in structural walls.
2. Cracks in partition and infill walls; fall of
brittle cladding and plaster.
3. Falling mortar from the joints of wall panels.
Grade 3
Substantial to heavy damage
(moderate structural damage, heavy
non-structural damage)
1. Large and extensive cracks in most
walls.
2. Roof tiles detach.
Chimneys fracture at the roof line.
3. Failure of individual non-structural
elements (partitions, gable walls etc.).
1. Cracks in columns and beam-column joints of
frames at the base and at joints of coupled
walls.
2. Spalling of concrete cover, buckling of
reinforced bars.
3. Large cracks in partition and infill walls,
failure of individual infill panels.
Grade 4: Very heavy damage (heavy structural
damage, very heavy non-structural
damage)
1. Serious failure of walls (gaps in
walls).
2. Partial structural failure of roofs and
floors.
1. Large cracks in structural elements with
compression failure of concrete and fracture of
rebars.
2. Bond failure of beam reinforcing bars; tilting
of columns.
3. Collapse of a few columns or of a single
upper floor.
Grade 5: Destruction
(very heavy structural damage)
1. Total or near total collapse of the
building.
1. Collapse of ground floor parts (e.g. wings) of
the building.

19. RESULTS AND DISCUSSIONS
19
33%
59%
8%
BUILDING DISTRIBUTION
MASONRY RCC COMPOSITE
9%
71%
20%
SOIL CONDITION
SOFT MEDIUM HARD

20. 211
124
12
0
50
100
150
200
250
1ST STOREY 2ND STOREY 3RD STOREY
NUMBEROFBUILDINGS
NUMBER OF STORIES

21. 67
155
128
0
20
40
60
80
100
120
140
160
180
BAD MEDIUM GOOD
NUMBEROFBUILDINGS
MAINTANANCE
BAD MEDIUM GOOD

22. 6
33
86
103
44
29
10
14
4 6
15
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 >10
NUMBEROFBUILDINGS
NUMBER OF MEMBER

23. 13
38
53
70
63
39 37
17
9
6 5
0
10
20
30
40
50
60
70
80
NEW 5 Yr 10 Yr 15 Yr 20 Yr 25 Yr 30 Yr 35 Yr 40 Yr 45 Yr 50 Yr
NUMBEROFBUILDINGS
AGE OF BUILDINGS

24. 24
12%
32%
49%
5%
HORIZONTAL BANDS
1 BAND 2 BAND
3 BAND NO BAND
7%
56%
37%
DIAPHAGRAM ACTION
EXIST
DON'T EXIST
DON’T KNOW

25. 36%
64%
FALLING HAZARDS
EXIST DON'T EXIST
19.00
%
81.00
%
POUNDING
EXIST DON'T EXIST

26. 5%
95%
SHORT COLUMN
EXIST DON'T EXIST 26
10%
90%
SOFT STORIES
EXISTS DON’T EXISTS

27. 115
78 80
0
20
40
60
80
100
120
140
HI VI HEAVY OVERHANG
NUMBEROFBUILDINGS
HORIZONTAL IRREGULARITIES, VERTICAL IRREGULARITIES & HEAVY
OVERHANG
HI VI HEAVY OVERHANG

28. 0
53
0
9
3
28
6
0
28
7
45
0 0
16
13
3
5
18
10
0
7
2
49
0 0
4
0
2
0
10
20
30
40
50
60
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
NUMBEROFBULIDINGS
FEMA 154-2015 SCORE ANALYSIS
RCC MASONRY

29. 53
46
96
16
42
49
0
20
40
60
80
100
120
G5 G4 G3
NUMBEROFBUILDINGS
GRADES OF BUILDINGS
RCC MASONRY

30. Seismic Mapping of RVS score analysis
30

31. CONCLUSIONS
• In light of above results and discussions it has been
seen that out of total surveyed 350 buildings more than
half of the buildings (59%) are RCC structures, 33% are
load bearing walls, 8% composite structures building
• It is observed that 21% buildings constructed about 25
years ago are not suitable to sustain the strong seismic
shock. Moreover 11% buildings constructed about 30-
35 years back are obviously masonry buildings should
be strengthened immediately.
• It is seen that 23% buildings have Vertical Irregularities
and 33% buildings have Plan irregularities. Fortunately
the percentage of Vertical irregularities is less than Plan
irregularities, as the former is much more vulnerable
than the latter. Lastly 23% buildings have heavy
overhangs in buildings.
31

32. • The performance score of the residential buildings is
calculated by FEMA 154 (2015). it is seen all the
building need further evaluation as the performance
score of all these buildings are less than “2” which is
considered as cut-off score. All buildings belong to G3
to G5 grades.
• Near about 149 buildings may experience G3 type of
damage, 88 numbers of buildings may be
experienced G4 type damage and 69 buildings may
be experience G5 type damage in severe future
earthquake estimated by FEMA 154 (2015).
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33. FUTURE SCOPE OF THE STUDY
• The seismic vulnerability assessment of existing
structures is very much essential in the city of
Agartala as it is situated in the seismic zone V, the
worst zone in India.
• All other important building like hospital, school
buildings may be considered for future study
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34. REFERENCES
• Bernardini, A.,Giovinazzi, S.,Lagomarsino, S., Parodi, S. (2007). The vulnerability
assessment of current buildings by a macroseismic approach derived from the
EMS-98 scale. 3° National Congress of Earthquake Engineering, Girona, Spain
• Federal Emergency Management Agency (FEMA 154), (1988). Rapid Visual
Screening of Building for Potential Seismic Hazards: A Handbook (FEMA 154, 2015)
• Google Earth for valuable image and QGIS
• Indian Standard 13920:1993 Code of practice for ductile detailing of reinforced
concrete structures subjected to seismic forces Indian Standards, New Delhi
• Indian Standard 456:2000 Code of practice for plain and reinforced concrete Indian
Standards, New Delhi. Indian Standard 1893 (Part 1): 2002 Criteria for earthquake
resistant design of structures (Fifth Revision) Indian Standards, New Delhi.
• Sinha, R., and Goyal, A., (2004). “A National Policy for Seismic Vulnerability
Assessment of Buildings and Procedure for Rapid Visual Screening of Buildings for
Potential Seismic Vulnerability”, Department of Civil Engineering, Indian Institute of
Technology Bombay, India
• Wikipedia.
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35. Thank you
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