SEISMIC VULNERABILITY ASSESSMENT OF RESIDENTIAL BUILDINGS IN AGARTALA CITY USING RAPID VISUAL SCREENING METHOD

SEISMIC VULNERABILITY ASSESSMENT OF RESIDENTIAL BUILDINGS IN AGARTALA CITY USING
RAPID VISUAL SCREENING METHOD
NIT AGARTALA B.TECH PROJECT
CHAPTER 1 INTRODUCTION
In world mainly 15 tectonic plate exist namely Indo- Australian plate, Philippines plate, Pacific
plate, Juan De Fuca plate, North American plate, Cocos plate, Nazca plate, Caribbean plate,
Antarctic Plate, Scotia plate, Eurasian plate, Arabian plate, African plate, South American plate,
and Indian plate, among all plate’s India is resting on the Indian plate which is moving towards
north-east with a speed of 26-36mm/year having an area of 11,900,000 square km.
Fig 1.1 Indian plate (Wikipedia)
These earthquakes have affected the whole of the region which directly involves six neighbor-
hood countries namely Afghanistan, Pakistan, India, Nepal, Bhutan and Bangladesh. In a span of
114 years between 1897 and 2011 nine such deadliest earthquakes have taken place in India
which include- Assam Earthquake, 1897; Kangra Earthquake in Himachal Pradesh, 1905; Nepal
Bihar Earthquake, 1934; Quetta Earthquake, 1935; Assam Earthquake,1950; Killari Earthquake,
1993; Bhuj Earthquake, 2001, Kashmir Earthquake, 2005 and Sikkim Earthquake, 2011. These
earthquakes account for a loss of about 2,14390 human lives, besides damage to property and
infrastructure.
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The effects of earthquakes on the built environment are comprehensive and seriously disruptive.
It is seen that earthquakes do not kill people, buildings do. This is because most deaths and
physical losses from earthquakes are caused by buildings or other human construction collapsing
during or after an earthquake. Therefore by understanding the characteristics of the building
elements and their collective performance in earthquake tremor might contribute to the human
effort to build safer buildings, and reduce the vulnerability of the building itself. The population
explosion multiplied seismic risk and the encroachment of vulnerable built environment into
areas susceptible to seismic hazard. Due to its ubiquitous geo-climatic conditions, India has
traditionally been vulnerable to natural disasters especially earthquakes, which is considered to
be the most destructive with the potential of inflicting huge losses to life and property. Around
60% of the country’s landmass is prone to moderate, high or severe earthquake risks. The North-
Eastern part of the country continues to experience an earthquake with magnitude greater than
6.0 every year. The western part of the country around Kutch is also highly vulnerable as
evidenced by massive destruction during past earthquakes of the region. The Nepal earthquake
April, 2015and Bhuj Earthquake (Kutch, Gujarat) of 26 January, 2001 as shown in (Fig.1.2 and
Fig.1.3) caused a gigantic damage and thus emphasizes the need for seismic evaluation of huge
stock of existing buildings. So, the states highlight the need of seismic resistant building’s
construction as per latest modified seismic codes in which all the recent research and technical
advancements in this field and also the understanding of the behaviour of collapsed structures of
all past earthquakes are included. Seismic resistant designing of structures is the panacea of the
maximum seismic problems at least in zone IV and Zone V. To resist any massacre in the old
buildings we should rectify and check those buildings as per the codes on micro level. But our
country currently does not have the required technical skills and trained manpower to implement
any vulnerability assessment program on a large scale. Government must positively act as a
catalyst in this grim issue.
Fig 1.2 Earthquake effect at Nepal April, 2015 Fig.1.3 Earthquake effect at Gujrat (Bhuj),
2002
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Tripura (extends between 22°56'N and 24°32'N latitude and 90°09'E and 92°10'E longitude) is in
the zone of most severe seismic hazard (i.e., zone V; as per Indian standard code of practice for
earthquake-resistant design of structures, IS-1893 2002) in the country. Though no major
devastating earthquake has occurred in Tripura till today, then also due to its earthquake
proneness, there is a need for the assessment of the conditions of large numbers of existing
buildings. So this study proposes an approach to estimate the seismic vulnerability assessment of
residential buildings in Agartala city.
Fig 1.4 Seismic Zoning map of India from IS 1893(part 1):2002
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As per IS 1893:2002 (Part 1), India has been divided into 4 seismic zones (Fig.1.4). The details
of different seismic zones are shown in Table 1.1.
Table 1.1 Different seismic zones IS 1893(Part 1):2002
Zone II Low seismic hazard (maximum damage during earthquake may be up
to MSK intensity VI)
Zone III Moderate seismic hazard (maximum damage during earthquake may
be up to MSK intensity VII)
Zone IV High seismic hazard (maximum damage during earthquake may be up
to MSK intensity VIII)
Zone V Very high seismic hazard (maximum damage during earthquake may
be of MSK intensity IX or greater)
Fig 1.5 Survey area Date 10/11/2016, Google Map
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CHAPTER 2 REVIEW OF LITERATURE
2.1 GENERAL BACKGROUND
The subject revealed that many developed and developing countries around the world like Japan,
Turkey, USA, Switzerland, China, India, Bangladesh etc. has adopted various methodologies for
seismic vulnerability assessment in order to analyze defects in existing structures against
earthquake. Seismic vulnerability refers to the susceptibility of those parts of a building that are
required for physical support when subjected to an intense earthquake or other hazard. This
includes foundations, columns, supporting walls, beams and floor slabs. Many researches are
based on the capacity spectrum method (ATC 40) and are intended to provide a methodology for
determining the performance score of the building. Experimental investigation like rebound
hammer test was also used to assess the compressive strength of concrete structural members
wherever access was provided in reinforced concrete structure.
2.2 PREVIOUS RESEARCH
FEMA 154 (1988) revised in 2002 and 2015 reported that the Rapid Visual Screening (RVS)
procedure was used by private-sector organizations and government agencies to evaluate more
than 70,000 buildings nationwide. FEMA 154 provides a procedure that can be rapidly
implemented to identify buildings that are potentially seismically hazardous. In this method
damage grades has been assigned to each of the buildings.
FEMA P-154 defines collapse probability as the probability that the building will suffer
partial or complete collapse. In that part of the building, the gravity load carrying system (such
as beams, columns, floors and shear walls) loses the ability to carry its own weight and weight
of whatever else it supports. That failure leads to severe structural deformation of a potentially
life threatening nature, especially falling of all or portions of a structure. A potentially seismically
hazardous building is one where, with in the accuracy of the RVS procedure, the collapse
probability is estimated to be more than 1% in rate earthquake shaking (using the default cutoff
2.0).
The third edition update of FEMA P-154 occurred over the course of three years.
In the first year project team:
• Performed an extensive literature and research review that focused on RVS programs conducted
since 2002, existing RVS procedures.
• Developed a draft rapid visual screening methodology.
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• Benchmarked the draft rapid visual screening methodology and
• Developed an outline for the third edition of FEMA P-154.
In the second year, project team:
• Developed a draft third edition of FEMA P-154.
• Conducted a workshop to solicit feedback on the updated Handbook.
• Completed a 95% draft of third edition of FEMA P-154 and
• Completed a preliminary draft of the third edition of FEMA P-155.
In the third year, project team:
• Recalculated the basic scores and scores Modifiers using the most current information.
• Conducted trial runs with the updated basic scores and score modifiers and
• Completed the final version of third edition of FEMA P-154 and FEMA P-154 reports
The RVS procedure utilizes a methodology based on a "sidewalk survey" approach that involves:
 identification of the primary seismic force-resisting system and building materials,
 assignment of a Basic Score, which relates to the probability of the building collapse for a
specified earthquake recurrence interval, and
 assignment of Score Modifiers that relate to significant seismic-related defects the screener may
observe.
Application of the procedure results in a ranking of surveyed buildings, which may be divided
into two categories: (1) those acceptable as a risk to life safety, or (2) those that may be
seismically hazardous and should be analyzed in more detail by a professional engineer
experienced in seismic design.
The RVS procedure was developed for a wide range of screeners including civil engineers,
structural engineers, architects, design professionals, building officials, construction contractors,
firefighters, architectural or engineering students etc.
Sinha and Goyal (2003) developed the methodology Rapid Visual Screening of buildings for
potential seismic vulnerability. As wide variety of construction types and building materials are
used in urban areas of India, they include local materials such as mud and straw, semi -engineered
materials such as burnt brick and stone masonry and engineered materials such as concrete and
steel. The RVS procedure has considered 10 different building types. All buildings have been
divided into six vulnerability class, denoted as Class A to Class F based on the European Macro
seismic Scale (EMS-98) recommendations. The buildings in Class A have the highest seismic
vulnerability while the buildings in Class F have lowest seismic vulnerability.
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The probable damage can be estimated based on the RVS score and is given below. Table 2.1
should only be used as indicative to determine the necessity of carrying out simplified
vulnerability assessment of the buildings.
Table 2.1 Expected damage level as function of RVS score (Sinha & Goyal IIT Bombay,
2003)
RVS SCORE DAMAGE POTENTIAL
S < 0.3 High probability of Grade 5 damage; Very high probability of Grade 4
damage
0.3 < S < 0.7 High probability of Grade 4 damage; Very high probability of Grade 3
damage
damage
damage
1.3 < S < 1.5 Probability of Grade 1 damage
S > 1.5 Probability of Grade 0 damage
Giovinazzi and Lagomarsino (2004) proposed a macro seismic method that leads to the
definition of damage probability functions based on the EMS-98 macro seismic scale. The EMS
-98 scale defines qualitative descriptions of “Few”, “Many” and “Most” for five damage grades
for the levels of intensity ranging from V to XII for six different classes of decreasing
vulnerability (from A to F). Damage matrices containing a qualitative description of the
proportion of buildings that belong to each damage grade for various levels of intensity are
presented in Table 2.2 for vulnerability class C
Table 2.2 A Damage Model for Vulnerability Class C as presented in EMS-98
Damage
Level
Intensity
Damage Grade
0 1 2 3 4 5
V Few
VI Few
VII Few
VIII Many Few
IX Many Few
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X Many Few
XI Many
XII Most
Alam et al. (2010) made a comparison between seismic vulnerability assessment techniques for
buildings to evaluate their suitability for use in seismic risk assessment. The methods considered
are ‘‘Hybrid’’ vulnerability assessment method, FEMA 154 (Rapid Visual Screening), Euro
Code 8, New Zealand Guidelines, Modified Turkish method and NRC Guidelines.
Jain et al. (2010) proposes a RVS method for RC-frame buildings in India based on systematic
studies on damage data of the 2001 Bhuj earthquake. The earthquake witnessed large scale
damages and collapse of about 130 RC-frame buildings, leading to many fatalities due to open
ground stories, short columns, irregular configurations, torsional irregularities, pounding effects
etc. A team from Centre for Environmental Planning and Technology (CEPT) University,
Ahmedabad surveyed 6670 buildings of Ahmedabad from which a representative sample of 270
RC-frame buildings was chosen and assigned different damage grades (G0: no damage to G5:
collapse).
Srikanth et al. (2010) reported in the research paper that they adopted the RVS methodology and
it was conducted on 16000 buildings. RVS is a ‘‘sidewalk survey” in which an experienced
screener visually examines a building to identify features that affect the seismic performance of
the building, such as building height, frame action, pounding effect, structural irregularity, short
columns, heavy overhangs, soil conditions, falling hazard, apparent building quality, diaphragm
action etc. On the basis of above mentioned parameters, performance score of the buildings has
been calculated.
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CHAPTER 3 OBJECTIVES OF THE STUDY
In India major earthquake is rare but each earthquake is characterized by high exposure and
their economic and social effects cannot be neglected. AGARTALA lies in one of the most
seismically active zones of India and also possibility of future earthquakes of moderate to
great nature cannot be ruled out. Even after the modification of the seismic codes, the
buildings are not constructed as per the codes. In this regard, a comprehensive study of
seismic risk assessment of residential buildings of AGARTALA is necessary. In the previous
chapter it has been observed that the various researchers have used various methods for
finding out seismically vulnerable buildings. However, the rapid visual screening is the 1st
level procedure which is used to screen the building stock. In this respect the main objective
of the present study is summarized as follows:
1. To assess the seismic vulnerability of residential buildings in Agartala city using different
Rapid Visual Screening Method proposed by FEMA 154 (2015).
2. To predict the expected damage grade that may be observed in the surveyed
buildings in future severe earthquake.
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CHAPTER 4 METHODOLOGY
Existing buildings can become seismically deficient since seismic design code
requirements are constantly upgraded and there is continuous advancement in engineering
knowledge. Indian buildings built over past two decades are seismically deficient because of lack
of awareness regarding seismic resisting measures. The identification of seismically vulnerable
buildings and neighborhoods is a necessary first step in developing effective disaster mitigation
programs for the community. Even though such assessment tools exist in other seismic countries
such as U.S.A and Turkey, these are not applicable to Indian building typologies. Hence a need
has long been felt to develop methodologies of building stock that can be applied to Indian
buildings.
India’s national vulnerability assessment methodology, as a component of earthquake
disaster risk management framework should include the following procedures:
1. Rapid visual screening (RVS) – (Level 1 procedure). This procedure is recommended for all
building stocks.
2. Simplified vulnerability assessment (SVA) – (Level 2 procedure). This procedure is
recommended for all buildings with high concentration of people.
3. Detailed vulnerability assessment (DVA) – (Level 3 procedure). This procedure is recommended
for all important and lifeline buildings.
4.1 RAPID VISUAL SCREENING PROCEDURE (RVS)
4.1.1 Introduction
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 1990s. This RVS procedure was originally developed for typical
constructions in US, have also been widely used in many other countries after suitable
modifications. The most important feature of this procedure is that it permits vulnerability
assessment based on walk-around of the building by a trained evaluator.
4.1.2 Importance
The Rapid Visual screening is carried out for all considered buildings. It permits quick visual
vulnerability assessment. The purpose of the Rapid Visual Assessment (RVA) is to determine
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the adequacy of the structural facility as to whether the facility will be able to withstand the
expected earthquake. For scenario earthquakes, performance levels for existing building stock
need to be assessed.
4.1.3 Procedure
Rapid vulnerability assessment is the first necessary step but may not be sufficient to establish
building stock performance levels. Necessary information for evaluation of structure is obtained
either by conducting a field survey or from building typology, if available or from both. If plan
is available, then the field party must check and verify the present status of the building. In this
method, buildings are evaluated qualitatively in terms of structural characteristics, structural
configuration, and the degree of deterioration of the building. This method is rapid and
inexpensive and helps in identifying structures, which are clearly hazardous and the structures for
which detailed hazard evaluation is sought.
4.1.4 Survey parameters
The most pertinent information required to establish rating for building is based on the parameters
of building. These are:
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.
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.
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4.1.5 Factors affecting building vulnerability
Seismic vulnerability of a building is the amount of probable damage induced to it by a particular
level of earthquake intensity. It occurs large near the building situated above the focus. It depends
upon mainly:-
4.1.5.1 Building Structure
Buildings are designed to resist vertical and horizontal forces acting on them. This quantity is
achieved mainly in three ways:
4.1.5.(a) Frame structure: In this type of structure, the entire load acting on the building are
carried out by the frame of reinforced concrete or steel beams, columns and slabs transmitted
through the foundation to the soil beneath.
4.1.5.(b) Load bearing structure: In this structural system the arrangement of masonry units
such as bricks, stones or concrete blocks bonded by mortar transmit all the load acting in the
structure.
4.1.5.(c) Composite structure: This is the combination of frame and load bearing structure.
4.1.5.2 Building Height
Building height and natural period of buildings affects the buildings behavior during occurrence
of an earthquake. Apart from the ground vibrating in multiple directions; buildings also vibrate
in different directions and hence have multiple modes. Each of these modes has a period and the
longest period known as the natural frequency. If the ground motion frequency is close or equal
to natural frequency of building, resonance occurs which amplify the building response.
The approximate frequencies of buildings are 10 for a one storied building, 2 for a 3-4
storied building, 0.5 to 1.0 for a tall building and 0.17 for a high-rise building.
4.1.5.3 Structural Irregularities
4.1.5.3(a) Vertical irregularity
Vertical irregularities can be judged from the structural system like Setbacks in elevation. The
vertical irregularities make a building far more vulnerable as compared to the plan irregularities.
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Fig.4.1 Presence of Setbacks (Image Courtesy Patel, C.N., and Patel, P.V, 2010)
4.1.5.3(b) Plan Irregularity
Irregularity in the plan caused due to various shapes (L, T, U, +) causes torsion during earthquake
and is responsible for major damage.
Fig.4.2 Irregular Plan Configuration and separation joints (Image Courtesy Patel, C.N.,
and Patel, P.V, 2010)
4.1.5.4 Apparent Quality
Visible Quality of the material used in the construction works is known as apparent quality. It
also depends upon workmanship and materials used during construction.
4.1.5.5 Soil Condition
Soil is classified as hard, medium and soft. The hard soil is considered to be better than any other
type of soil.
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4.1.5.6 Frame action
Frame Action is to be present in the RCC buildings to transfer the load uniformly to the ground.
Fig.4.3 Complete and Incomplete Frame action (Image Courtesy Patel, C.N., and
Patel, P.V, 2010)
4.1.5.7 Diaphragm Action
The main function of a horizontal element is to distribute and transfer horizontal seismic load to
the vertical load-bearing element that is the wall below it.
4.1.5.8 Heavy Overhangs
Heavy overhangs refer to extra projections of a building; can be dangerous because they are
subjected to greater seismic forces during an earthquake.
Fig 4.4 heavy overhanging (Image Courtesy Patel, C.N., and Patel, P.V, 2010)
4.1.5.9 Soft Stories
Absence of partition walls in ground or any intermediate stories for shops or other commercial
use.
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Fig.4.5 Soft Storey (Image Courtesy Patel, C.N., and Patel, P.V, 2010)
4.1.5.10 Short Column Effect
Partial height walls adjoining to columns, give rise to short column effect in RC building. These
short columns are not free to deflect over the entire length.
Fig.4.6 Short Column Effect (Image Courtesy Patel, C.N., and Patel, P.V, 2010)
4.1.5.11 Pounding Effect
Pounding is the result of irregular response of adjacent
building of different heights and different dynamic
characteristics. When two buildings are too close to each
other, they may pound on each other during strong
shaking.
Fig.4.7 Pounding Effect (Image Courtesy Patel, C.N.,
and Patel, P.V, 2010)
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4.1.5.12 Large and Asymmetrical Openings
Large openings weaken the masonry walls against vertical as well as soft storey effect for
horizontal seismic load.
4.1.5.13 Structural Bands
4.1.5.13(a) Plinth band: This band is provided at base level for even distribution of the super
structure load to the foundation structure. This is important where soil is soft or uneven.
4.1.5.13(b) Lintel band: This is the most important band and should be provided in all storeys
in buildings.
4.1.5.13(c) Roof band: This band will be required at eave level of trussed roofs and also below
or in level with such floors, which consists of joists and covering elements so as to properly
integrate them at ends and fix into the walls.
4.1.5.14 Water Tank at roof:
It has lot of dead load and if they are placed near the center of plan they may cause large amount
of torsion. They can be classified into three categories:
(a) Doesn’t exist (b) Capacity < 5000 liter (c) Capacity > 5000 liter
4.1.5.15 Falling Hazards
Falling Hazards have contributed more to the causalities than any feature of a building. Towers
and large hoardings that is likely to fall during earthquake.
4.1.5.16 Basement
The buildings without basement suffered higher level of damage as compared to the buildings
with basement. This may be because buildings without basement tend to have significantly larger
storey height in the lowest storey.
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CHAPTER 5 DETAILS OF CASE STUDIES
Agartala, the capital of Tripura has an area of about 58.84 sq. km. And the total Ward Numbers
of Agartala Municipality Council are 17. As in this stipulated time period the buildings of
municipality area cannot be surveyed. So, to assess the vulnerability of buildings of Agartala city
by Rapid visual Screening Method three different areas have been chosen to carryout door to door
survey for collecting the information regarding various parameters. The details of the selected
areas are given below.
5.1 CASE STUDY OF RESIDENTIAL BUILDINGS IN DHALESWAR AREA
In this phase, visual screening was carried out for Dhaleswar area. Dhaleswar, east zone ward
no.-4, Agartala Municipal Council, is located at latitude 23 ̊49’53.57”N & longitude
91 ̊17’44.54”E. The side walk survey was conducted in a phased manner between 25 august
August,2016 to 2th
November ,2016.The road no’s are respectively – 7,9,10,14,15,16 and 17,
which was surveyed during this period. From the side walk survey information of the building
was collected in data sheet as given in Table no.5.1 and Table no. 5.2.The time required per
building to complete the data sheet was 20- 30 minutes. A digital photograph was taken after
permission of building owner. Total 206 no’s of residential buildings are surveyed. Among them
134 comprise RCC structures, 62 comprise masonry constructions, 10 are Composite structures
and the remaining is mixed type.
Our case study of seismic vulnerability of Dhlaeswar area reveals a gloomy picture as few
buildings are not suitable to sustain seismic shocks as those were built approximately 30 to 40
years back and as a result consciousness of people should be increased about the same. Apart
from that as mass gathering happens there, structural material condition should also be checked
in parallel. So there is an urgent need to understand the seismic vulnerability of existing buildings
and take appropriate measures to reduce the risk.
The reason for choosing this area is due to (i) large population and (ii) large number of residential
buildings both RCC and masonry constructions.
RVS formats usually record the important components of seismic vulnerability and
propose a scoring system that forms the basis for classifying buildings in different risk categories.
The RVS format of Masonry building is shown in the following table:
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Table 5.1 Rapid Visual Survey for Masonry buildings
RAPID VISUAL SURVEY FOR MASONRY BUILDINGS
[FOR EARTHQUAKE SAFETY AT AGARTALA]
Lat:23 50 10.73
Long: 91 17 57.57
RAPID VISUAL SURVEY OF MASONRY BUILD-
INGS FOR EARTHQUAKE SAFETY
SEISMIC ZONE V
Name & Address/Location/Street: SAWAPAN KR.
NATH
DHALESWAR ROAD NO:D17R08
Number of members:4
CITY: AGARTALA FULL ACCESS
Year of construction:2001 STATE: TRIPURA PARTIAL
ACCESS
Type of
construction
Brick
masonry
YES
Stone
masonry
Composite
YES
Number of floors 2 NO ACCESS
Foundation
YES
Existing
Use Residential-
Yes
Commercial Mixed Other Please
specify
CHECKLIST OF OBSERVABLES IN MASONRY
BUILDINGS
COMMENTS
Structural irregularities
Lack of adequate walls in orthogonal directions
Heavy overhangs
Reentrant corners
YES
YES
YES
Apparent quality
Apparent quality of materials and construction
Maintenance
MEDIUM Crack- Absent
Dampness- Present
Soil conditions MEDIUM
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Pounding
Contiguous buildings
Poor apparent quality of adjacent buildings
NO
Openings
Large openings in walls
Irregularly placed openings
YES
Diaphragm Action
Evidence of absence of diaphragms
Evidence of large cut outs in diaphragms
NO
Other features
Horizontal bands at plinth level
Horizontal bands at lintel level
Horizontal bands at roof level
Horizontal bands at sill level
Arches present or absent
YES
YES
YES
NO
ABSENT
Random rubble stone masonry
Presence of thick walls 600 mm and above
NO
Falling hazards
Non- structural elements such as elaborate parapets,
AC unit grilles, elevation features, advertisement
hoardings, roof signs, marquees etc
NO
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Wall thickness at ground floor
External
Internal
10 INCH
Water tank at roof
Capacity
Location- Symmetrically placed or not
Present
1000 ltr
Corner
Basement
Full or partial
Absent
FORM 1-B Performa for Masonry Buildings
RAPID VISUAL SURVEY OF MASONRY BUILDINGS
FOR EARTHQUAKE SAFETY
CALCULATION SHEET MASONRY
FALLING HAZARD IDENTIFIER
F
Seismic zone Base score
Marquees/ hoardings/
Roof signs
Stories V 100
AC units / Grillwork 1 or 2 100
Elaborate parapets 3 85
Heavy elevation features 4 70
Heavy Canopies 5 50
Substantial Balconies
Heavy Cladding
Structural Glazing
No of storey 1 or 2 3 4 5 Vulnerability Score
Modifiers
Vulnerability Scores [VS] VSM
Structural
irregularity
-10 -10 -10 -10
Doesn’t exist=0
-10Exists =1
Good =0 -10
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Apparent
Quality
-10 -10 -10 -10 Moderate =1
Poor =2
Soil Conditions 10 10 10 10
Medium =0 0
Hard =1
Soft =-1
Pounding 0 -3 -5 -5
Doesn’t exist=0 0
Normal apparent condition
of adjacent building=1
Poor apparent condition of
adjacent building=2
OPENINGS 0 -5 -5 -10
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Wall
openings
-5 -5 -5 -5
Small [less than 1/3]=0 -5
Moderate [ Between 1/3
and 2/3]=1
Large[Above 2/3]=2
Orientation
of openings
-2 -5 -5 -5
Regular 0
Irregular
Other features
Horizontal
bands
20 20 20 20
Exist=1 20
Don’t exist=0
Arches -10 -10 -10 -10
Exist=1
Don’t exist=0
Stone masonry
Random
Rubble
Stone
Masonry
Walls
-15 -15 -15 -15
Remedial measures
exist=0
-15
Don’t exist=1
Water tank
at roof
capacity
0 -3 -4 -5
Doesn’t exist=0 0
Capacity<5000lit=0.5
Capacity>5000lit=1
Location of
water tank
0 -3 -4 -5
Symmetric=0 0
Unsymmetrical=1
Basement
– full or
partial 0 -3 -4 -5
Don’t exist=0 0
Exist=1
∑[VSM*VS]
Performance score =BS- ∑[VSM*VS] Performance score 80
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FIELD SUYVEY BY: REVIEWED BY: APPROVED BY:
DATE:22-10-2011 DATE: DATE:
Table 5.2 Rapid Visual Survey for RCC buildings
Rapid Visual Survey for RCC Framed Buildings
[For Earthquake safety at Agartala]
Lat:23 50 10.39
Long:91 17 55.61
RAPID VISUAL SURVEY OF RCC FRAME BUILD-
INGS FOR EARTHQUAKE SAFETY
SEISMIC ZONE V
Name & Address/Location/Street: BHUPENDRA
BHOWMIK
DHALESWAR ROAD NO:D17R06GL5
Number of members:4
CITY: AGARTALA FULL ACCESS
Year of construction:2014 STATE: TRIPURA PARTIAL AC-
CESS
Type of
construction
RC frame NUMBER OF FLOORS 1 NO ACCESS
FOUNDATION
YES
EXIST-
ING
Use Residential
YES
Commercial Mixed Other Please
specify
CHECKLIST OF OBSERVABLES TICK COMMENTS
Soft storey
Open parking at ground level
Absence of partition walls in ground or any intermediate
storey for shops or other commercial use
Taller heights in ground or any other intermediate storey
YES
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Vertical irregularities
Presence of setbacks
Buildings on slopy ground
YES
Plan irregularities
Irregular plan configuration
Reentrant corners
NO
Heavy overhangs
Moderate horizontal projections
Substantial horizontal projections
Absent
Apparent Quality
Apparent quality of materials and construction
Maintenance
Moderate Crack and dampness- Absent
Short column
Size of column at GF
NO
Pounding NO
Soil condition MEDIUM
Frame action NO
Falling hazards
Non-structural elements such as elaborate parapets,
AC unit grilles, elevation features
Absent
Water tank at roof
Capacity
Location – symmetrically placed
Present
500 ltr
Corner
Basement-
Full or partial
Absent
FORM 2-B Performa for Reinforced Concrete Buildings
RAPID VISUAL SURVEY OF RCC FRAME BUILDINGS FOR EARTH-
QUAKE SAFETY CALCULATION SHEET RCC FRAME
FALLING HAZARD IDENTIFIER F Seismic zone Base score
Marquees/ hoardings/
Roof signs
Stories V 100
24

AC units / Grillwork 1 or 2 100
Elaborate parapets 3 90
Heavy elevation features 4 75
Heavy Canopies 5 65
Substantial Balconies >5 6
Heavy Cladding
Structural Glazing
Number of
storey
1 or 2 3 4 5 >5
Vulnerability Score
Modifiers
Vulnerability Scores [VS] VSM
Soft storey 0 -15 -20 -25 -30
Doesn’t exist=0
0
Exists =1
Vertical
irregularities
setbacks,
Buildings on
slopes
-10 -10 -10 -10 -10
Doesn’t exist=0
Exists =1
-10
Plan
irregularities -5 -5 -5 -5 -5
None =0
0Moderate=1
Extreme=2
Heavy overhangs -5 -10 -10 -15 -15
Doesn’t exist=0
0
Exists =1
Apparent quality -5 -10 -10 -15 -15
Good =0
-5
Moderate =1
Poor =2
Short columns
-5 -5 -5 -5 -5
Doesn’t exist=0 0
Exists =1
Pounding
0 -5
Doesn’t exist=0 0
Unaligned floors=2
25

Poor apparent quality of
adjacent buildings=2
Soil condition 10 10 10 10 10
Medium=0 0
Hard=1
Soft=1
Frame action 10 10 10 10 10
Doesn’t exist=0 0
Exists =1
Not sure=0
Water tank at
roof 0 -3 -4 -5 -5
Doesn’t exist=0 0
Capacity<5000lit=0.5
Capacity>5000lit=1
Location at
water tank
0 -3 -4 -5 -5
Symmetric=0 0
Unsymmetrical=1
Basement –
0 3 4 5 5
Don’t exist=0 0
Exist=1
∑[VSM*VS]
PERFORMANCE SCORE= BS-∑[VSM*VS] PERFOR-
MANCE
SCORE
85
FIELD SURVEY: REVIEWED BY: APPROVED BY:
DATE:22-10-2016 DATE: DATE:
26

CHAPTER 6 A COMPARATIVE STUDY OF RAPID VISUAL SCREENING
METHODS
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 1990s. This RVS procedure was originally developed for
typical constructions in US. Many developed and developing countries around the world
have adopted various methodologies for seismic vulnerability assessment in order to
analyze defects in existing structures against earthquake. In the Indian context Jain et al.
(2010) proposed a RVS methodology only for the R.C.C buildings and Srikanth et al.
(2010) proposed a methodology for both R.C.C and Masonry buildings. In this current
study these three methods have been used to find the vulnerability classes. So a comparative
study of these methods is presented below. Table 6.1 shows the various vulnerability factors
considered in the three different methods.
Table 6.1 Major vulnerability factors considered in vulnerability assessment methods
Vulnerability
assessment
No
of
story
VI PI Soft
story
Heavy
overhang
Short
Column
Poun
ding
effect
Base-
ment
Quality Water
Tank
Soil
Type
FEMA
154_508
METHOD
Y Y Y Y N Y Y N N N Y
SRIKANTH
METHOD
Y Y Y Y Y Y Y Y Y Y Y
In Table N represents not considered and Y represents considered
6.1 FEMA 154 (2015)
FEMA 154(2015) was published originally in 1988 in US and latest revised in 2015 to categorize the potentialy
Seismically hazardous buildings of USA by Rapid visual screening method. It is relatively a quick procedure in
developing a list of potentially risky buildings. The method considers 17 different building types based on the
building materials and construction types commonly found in urban areas of USA. Five regions of seismicity:
low (L), moderate (M), moderately high (MH) high (H) and Very high (VH) is considered in this guidelines. This
Method also assigns a basic structural score based on the lateral force resisting system of the building. The number
27

of stories, plan and vertical irregularities, pre-code or post-benchmark code detailing, and soil type effects the
Performance modifiers.
Table.6.2 shows the basic scores and the modifiers assigned by FEMA 154 (2015) for moment resisting frame
buildings based on 10 scales. It shows a pre-code penalty and post-benchmark positive attribute for buildings
constructed after the significant improvements in the code. The pre-code and post-benchmark modifiers have
been given significant importance when compared to the basic structural scores.
Table 6.2 Basic scores and modifiers for moment resisting frame buildings (FEMA 154, 2015)
28

NIT AGARTALA B.TECH PROJECT 29

6.2 Method proposed by Srikanth et al. (2010)
After Bhuj earthquake of 26 January 2001, Rapid Visual Screening (RVS) was conducted
on 16000 buildings in Gandhidham and Adipur cities. A RVS Methodology is developed
by the researchers for both Masonry buildings and R.C.C Structures. The evaluation is
based on some structural parameters of building. These are building height, frame action,
pounding effect, structural irregularity, short columns, heavy overhang, soil conditions,
falling hazard, apparent building quality, diaphragm action etc. On the basis of above
mentioned parameters, performance score of the buildings has been calculated. The
formula of the performance score is given as
PS= (BS) – Σ [(VSM) x (VS)]
Where BS represents Basic Scores, VSM represents the Vulnerability Score Modifiers and
VS represents the Vulnerability Score.
The data analysis of both types of the existing buildings in the region is scrutinized on the
basis of Gaussian (Normal) distribution.
Table 6.3 Base Score and Vulnerability Scores for R.C.C buildings by Srikanth et al. (2010)
No. of
Stories
Base Score
for Zone V
(BS)
Vulnerability Scores (VS)
Soft Story Vertical
irregularity
Heavy
overhang
Apparent
Quality
Short
Column
Pounding
1 or 2 100 0 -10 -5 -5 -5 0
3 90 -15 -10 -10 -10 -5 -2
4 75 -20 -10 -10 -10 -5 -3
5 65 -25 -10 -15 -15 -5 -3
6 or 7 60 -30 -10 -15 -15 -5 -3
Table 6.4 Base Score and Vulnerability Scores for Masonry buildings by Srikanth et al. (2010)
No. of
Stories
Base Score
for Zone V
(BS)
Vulnerability Scores (VS)
Structural
irregularity
Diaphragm
Action
Arches Apparent
Quality
Pounding Water
Tank
1 or 2 100 -10 -10 -10 -10 0 0
3 85 -10 -15 -10 -10 -3 -3
4 70 -10 -15 -10 -10 -5 -4
5 50 -10 -15 -10 -10 -5 -5
30

6.3 Damage Grades
The damage classifications based on the European Macro-seismic Scale (EMS-98) define
building damage to be in Grade 1 to Grade 5 which is shown in Table 6.6. These are used
in RVS to predict potential damage of a building during severe earthquake.
Table 6.5 Classification of damage grade to buildings (EMS-98)
DAMAGE GRADE MASONRY BUILDINGS R.C.C STRUCTURES
Grade 1:
Negligible to slight damage
(No structural damage,
slight non-structural dam-
age)
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 infills.
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 and mumptys.
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
nonstructural damage)
1. Large and extensive
cracks in most walls.
2. Roof tiles detach.
Chimneys fracture at the
roof line.
3. Failure of individual
nonstructural elements
(partitions, gable walls etc.).
1. Cracks in columns and
beamcolumn 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.
31

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.
Among two RVS Methodologies Srikanth et al. damage grades are not considered. As have
the performance scores in 100 scales the damage grades assigned by Jain et al. is considered
in Srikanth method. Whereas in FEMA P-154 the predicted damage grades considered in
this method is defined by Sinha and Goyal (A National Policy for Seismic Vulnerability
Assessment of Buildings and Procedure for Rapid Visual Screening of Buildings for
Potential Seismic Vulnerability) and the performance score is based on 10 scales. Table 6.6
shows the predicted damage grades.
Table 6.6 Predicted Damage Grades
Damage grades G0 G1 G2 G3 G4 G5
Performance score
calculated by FEMA 154 S>1.5 1.2<S<1.5 1≤S≤1.2 0.7≤S≤0.9 0.4≤S≤0.6 S<0.4
Performance score
calculated by Jain et al. and
Srikanth et al.
S>100 90<S≤100 80<S≤90 70<S≤80 60<S≤70 S≤60
32

CHAPTER 7 RESULTS AND DISCUSSIONS
This study presents seismic vulnerability assessment of residential buildings in Agartala
city using RVS methodology. Survey of buildings was conducted and data on various
parameters like type of buildings, age of buildings, number of stories, apparent quality,
heavy overhangs, diaphragm action, horizontal bands, vertical irregularities and plan
irregularities have collected. Based on these data the performance score of each building
has calculated from which the predicted damage grade has assigned for each building.
Below mentioned sections shows the results of the present study in the pie and bar charts
for both residential and school buildings.
7.1 RESIDENTIAL BUILDINGS OF DHALESWAR
7.1.1 Type of Structures
Based on survey data, Fig.7.1 shows that a variety of building types exist, however 65% of
buildings are constructed with RCC, 30% of the buildings are masonry types and 5% are
composite structures. The reinforced concrete structural type consists of clay brick bearing
walls, confined with caste in place concrete columns and beams, which imports some
ductility. But, URM structures, which have clay brick bearing walls and no concrete
columns, are not contributing any ductility.
Fig. 7.1 Type of structures
33

7.1.2 Age of buildings
The age of the building is one of the most important factors that should be taken in account
in order to study the seismic vulnerability assessment. Fig 7.2 shows that 5 buildings are
new, 26 buildings are about 5years ago, 27 buildings are about 10 years ago, 40 buildings
near about 15 years ago, 46 buildings are of 20 years ago, which is maximum in group,
24buildings are 25 years ago, 22 buildings are 30 years ago, 8 buildings are 35 years ago,
4 buildings are 40 years ago, 2 buildings are 45 years ago, and 2 buildings are above 50
years ago. Buildings are constructed after 2005 are sustainable for Earthquake.
Fig. 7.2 Age of buildings
7.1.3 Analysis of storeys
The buildings of this area are mostly single or two storied. All the surveyed buildings are
residential type. In the case of masonry buildings, all the buildings in the area are up to 2
storied. In the case of RCC buildings, all the buildings are below 4 storied or mostly up to
34

3 storied. General observation is that most the RCC buildings have been constructed after
2001 and will have naturally some shear capacity to tolerate low level of seismic shaking.
But in the case of masonry buildings, due to lack of reinforcement, the capacity of resisting
the seismic load is quite doubtful. Fig.7.1.3 shows the number of stories of buildings.
Fig.7.3 Number of stories
7.1.4 Analysis of apparent quality
Material, workmanship and maintenance create a building’s quality. Fig. 7.4 shows the
apparent quality of buildings. It is observed that 80buildings are of good quality out of 206
buildings. Among these good quality buildings some are constructed in recent past and the
buildings which are constructed recently are followed by the guideline of seismic codes and
for that reason crack and dampness are negligible. 78 buildings are of moderate quality, as
these are constructed earlier and are not followed by the guidelines of seismic codes. And
the remaining 48 buildings are of poor quality which is constructed 40 or 60 years ago as a
result excessive cracks and dampness are found
116
82
8
0
0
20
40
60
80
100
120
140
1ST STOREY 2ND STOREY 3RD STOREY 4TH STOREY
NUMBEROFBUILDINGS
NUMBER OF STORIES
35

Fig.7.4 Apparent quality
7.1.5 Analysis of Heavy Overhangs, Plan Irregularity and Vertical Irregularities
In multilevel reinforced concrete buildings shift the mass center upwards, increasing
seismic lateral forces and moments for overturn during earthquakes. The plan irregularities
in buildings (L-shaped, T shaped or U-shaped) cause torsion during earthquake and are
responsible for major damage. Among the surveyed buildings most of them are L shape,
and very few are U shape. Vertical irregularities can be judged from the structural system
like Setbacks in elevation. The vertical irregularities make a building far more vulnerable
as compared to the plan irregularities.
Fig. 7.5 shows that 58 buildings have heavy overhangs or horizontal projection,80 buildings
having plan irregularities and 61 buildings are found with presence of setbacks.
36

Fig. 7.5 Heavy overhanging, horizontal irregularities, vertical irregularities
7.1.6 Analysis of diaphragm action
Fig 7.6 shows that 37% of the total surveyed masonry buildings have diaphragm action and other
features are given diagram.
Fig.7.6 Diaphragm Action in masonry buildings
37

Fig 7.7 Soil Conditions
Fig 7.8 Number of Members
38

Fig 7.9 Soft Stories Fig 7.10 Short Column
Fig 7.11 Falling Hazards
34.50%
65.50%
FALLING HAZARDS
EXIST DON’T EXIST
39

7.1.7 Analysis of horizontal bands
Fig 7.13 shows that 50% of the total surveyed buildings have three horizontal bands i.e.
plinth band, lintel band and roof band. 31% buildings have two horizontal bands and 13%
buildings have only one horizontal band, whereas surprisingly some very old constructions
have no band.
Fig.7.12 Horizontal Bands in masonry buildings
7.1.8 Analysis of RVS Performance Score
7.1.8.1 According to FEMA 154 (2015)
Fig.7.14 shows that the performance scores of the surveyed buildings of Dhaleswar area
for both masonry & RCC structures are predominantly ranging between 0.2 through 1.5.
12 buildings have performance score greater than 1.2, 54 buildings have also scored
between 0.9 to 1.2, 39 buildings have scored between 0.6 to 0.9, 34 buildings having scored
between 0.3 to 0.6 and 67 buildings have scored less than or equal to 0.3. From the visual
assessment, it is seen that these buildings are in moderate condition and will not get collapse
under low seismic action. But there is a need of further evaluation i.e. preliminary
evaluation. Guide Lastly a large number of structures i.e. As per this line all the building
40

need further evaluation as the performance score of all these buildings are less than 2 which
is considered as cut-off score.
Fig.7.13 Performance Score by FEMA 154 (2015)
7.1.8.2 According to Srikanth et al. (2010)
Fig.7.15 shows that the performance scores of the surveyed buildings of Dhaleswar area
for both masonry & RCC structures are predominantly ranging between 65 through 120.
More than 40 buildings have scored greater than 100 and 46 buildings have scored between
90 to100. The buildings scoring from 80 to 90 are 56. 41 buildings have scored only
between 70 through 80. and 25 buildings scoring from 60 to 70.
41

Fig.7.14 Performance Score by Srikanth et al. (2010)
7.1.9 Damage Grade of residential buildings
In Agartala 206 residential buildings was surveyed during the period of 25th
August 2016
to 2th
Nov 2016. As R.C.C structures can only be evaluated by the two methods so a
representative sample of 206 buildings was taken out of the total buildings. These buildings
had been assigned different grades of damage (G0: no damage to G5: collapse) where G0
is no damage, G1 is slight nonstructural damage, G2 is slight structural damage, G3 is
moderate structural damage, and G4 is severe structural damage, G5 is collapse. The
performance score of these RCC buildings was calculated by the three methods namely
FEMA 154 (2015) Method, and Srikanth et al. (2010) and subsequently the buildings are
grouped to various damage grades. In the Fig.7.16 it is seen that Srikanth et al. (2010)
method underestimates the high grade damages specified by FEMA 154 (2015).
42

Fig.7.15 Comparative Study of RVS methods for residential buildings
43

7.1.10 SHOWING ANALYSIS BY RVS METHODS
Fig 7.16 showing analysis by FEMA 154-508, 2015
Fig 7.17 showing result of SRIKANTH Et. Al. Method
44

CHAPTER 8 CONCLUSIONS
This report presents a summary of work dealing with seismic vulnerability assessment
(SVA) of different building types like RCC, Masonry and Composite structures in
Dhaleswar, area buildings in Agartala city using Rapid Visual Screening Method. In this
report a classification of buildings are done depending on their performance score. It can
be said that the buildings with higher performance scores perform better compared to lower
performance scores. However the buildings which are in the middle range of performance
score are large in number and hence proposed to do the preliminary assessment of selected
buildings. The main results of this present study are as below
1. In light of above results and discussions it has been seen that out of total
surveyed 206 buildings more than half of the buildings (65%) are RCC structures, 30%
are load bearing walls, 5% composite structures building.
2. It is observed that 23% buildings constructed about 25 years ago are not suitable
to sustain the strong seismic shock. Moreover 18% buildings constructed about 30-35
years back are obviously masonry buildings should be strengthened immediately.
3. It is seen that 30% buildings have Vertical Irregularities and 39% 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 28%
buildings have heavy overhangs in buildings.
4. The performance score of the residential buildings is calculated by the three
vulnerability methods namely FEMA 154 (2015) and Srikanth et al. (2010). According to
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. Srikanth
et al. (2010) perform the analysis for Masonry, R.C.C and Composite structures. Out of the
total buildings 19.4% have a performance score of 100 which signifies that these buildings
meet the present codal guide lines and have the capacity to withstand lateral force. 22.3%
buildings scored between 90 -100. More than 39% buildings are 30 to 35 years old having
performance score within the range of 70-90 are in doubt and Preliminary Evaluation has
to be carried to come into concrete conclusion.
45

Lastly about 8% buildings have least performance score of 65 to 43 which may be less
resistance lateral force and may fall in danger in future.
5. Near about 39 buildings may experience G3 type of damage and more than 34
numbers of buildings may be experienced G4 type damage in severe future earthquake
estimated by FEMA 154 (2015). However, it is observed that Srikanth et al. (2010) method
underestimates the high grade damages specified by FEMA 154 (2015).
46

CHAPTER 9 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. Accordingly
to judge the vulnerability condition of building in this city, in the present study few areas
like Dhaleswar area has been selected which will not show the vulnerability as whole so,
in future other municipal area of Agartala city has to be selected to carry out the same work.
All otherimportant building like hospital, school buildings may be considered for future
study. However, the preliminary and detail study on the few surveyed building can be carry
out to judge the findings of RVS methods.
47

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), Washington, D.C
Giovinazzi, S., and Lagomarsino, S. (2004). “A Macro seismic Method for the Vulnerability
Assessment of Buildings”, Proceedings of the 13th World Conference on Earthquake Engineering,
Vancouver, Canada, Paper No. 896 (on CD).
Google Earth for valuable image,
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.
Jain, S. K., Kumar, M., Mitra, K., and Shah, M., (2010). “A proposed Rapid Visual Screening
Procedure for Seismic Evaluation of RC-Frame Buildings in India”, Earthquake Spectra 18, Volume
2, No. 3, pages 709-729.
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.
Srikanth, T., Kumar, R.P., Singh, A.P., Rastogi, B.K. and Kumar, S., (2010). “Earthquake
Vulerability Assessment of Existing Buildings in Gandhidham & Adipur Cities Kachchh, Gujarat”.
Thapaliya, R. (2006). “Assessing Building Vulnerability For Earthquake Using Field Survey and
Development Control Data, Nepal”.
Wikipedia.
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