Download Rapid Visual Screening for Seismic Evaluation of Existing Buildings

Rapid Visual Screening for Seismic Evaluation of Existing Buildings
in Himachal Pradesh
by
Pradeep Kumar Ramancharla, Rajaram Chenna, Swajit Singh Goud, Ajay Kumar Sreerama, Gugan Vignesh,
Bhargavi Sattar, Narender Bodige, Ravikanth Ch, Pulkit Velani, Raju Sangem, Krishna Babu
Report No: IIIT/TR/2014/-1
Centre for Earthquake Engineering
International Institute of Information Technology
Hyderabad - 500 032, INDIA
April 2014
Project Completion Report
Rapid Visual Screening for Seismic Evaluation of Existing Buildings in
Himachal Pradesh
Project Sponsored By
TARU Leading Edge Private Limited, New Delhi
Submitted By
International Institute of Information Technology (IIIT), Hyderabad
Technical Report No. 01-2014
Volume-I
April - 2014
Rapid Visual Screening of Himachal Pradesh
Participants
From
International Institute of Information Technology, Hyderabad
Ramancharla Pradeep Kumar
Chenna Rajaram
Swajit Singh Goud
Ajay Kumar Sreerama
Gugan Vignesh Selvaraj
Sattar Bhargavi
Bodige Narender
Ravikanth Chittiprolu
Pulkit Velani Dilip
Raju Sangam
Krishna Babu
From
TARU Leading Edge Private Limited, New Delhi
Shashank Mishra
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Rapid Visual Screening of Himachal Pradesh
Table of Contents
1. Introduction………………………………………...……………………………….….……6
2. Vulnerability Studies of cities…………….…………………………………….…….……6
2.1 Tehra, Iran…………….…………………………………………………...….…….……6
2.2 Dehradun, India…………….…………..………………………………...….…….……7
2.3 Basel, Switzerland………….…………..………………………………...….….….……7
2.4 Kanpur, India………….………….……..………………………………...….…….……7
2.5 Zeytinburnu, Turkey………….………….……..………...……………...….…….……7
2.6 Gandhidham, India………….…………….……………………………...….…….……7
3. Literature on vulnerability assessment methods………………………………….…..…8
3.1 International Practices in RVS………….………………….……..……...….…….……8
3.2 RVS methods in USA………...………….………………….……..……...….…….……8
3.3 FEMA 154……………………..………….………………….……..……...….…….……8
3.4 RVS in Greece………………...………….………………….……..……...….……...…10
3.5 RVS in Canada...……………...………….………………….……..……...….……...…10
3.6 RVS in Japan..………………...………….………………….……..……...….…….…..10
3.7 RVS in New Zealand………...………….………………….……..……...….……...…11
3.8 RVS in India………...………...………….………………….……..……...….…….…..11
4. Methodology………….…………………………………………………………………….11
4.1 Rapid Visual Screening………….…………………………………………………….11
4.1.1
Brick Masonry buildings...…………………………………………………….17
4.1.2
Hybrid buildings...…………….……………………………………………….17
4.1.3
Rammed earth buildings...…………….…………..………………………….17
4.1.4
Reinforced concrete buildings...…………….…………….... ………………..17
4.1.5
Stone masonry buildings...…………..……….……………... ……………….18
4.2 Preliminary Survey………….…………...…………………………………………….18
5. Conclusions…...…………………………………………………………………………….21
6. References…………………………………………………………………...……………...21
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Rapid Visual Screening of Himachal Pradesh
List of figures
1. Location of brick masonry buildings through RVS in the districts of Himachal
Pradesh…………………………..…………………………………………………..….12
2. Normal distribution curve for brick masonry buildings through RVS ……….....12
3. Location of Hybrid buildings through RVS in the districts of Himachal
Pradesh …………………………………………………………………………………13
4. Normal distribution curve for Hybrid buildings through RVS…………………...14
5. Location of Rammed earth buildings through RVS in the districts of Himachal
Pradesh ……………………………….……………………………..………………….14
6. Normal distribution curve for Rammed earth buildings through RVS …………15
7. Location of Reinforced concrete buildings through RVS in the districts of
Himachal Pradesh ……………………………………………………………..………15
8. Normal distribution curve for Reinforced Concrete buildings through RVS....…16
9. Location of stone masonry buildings through RVS in the districts of Himachal
Pradesh…………………………………………………………………………..……...16
10. Normal distribution curve for Stone masonry buildings through RVS ………….17
11. Normal distribution curve typology wise ………………………………......………18
12. Schematic diagram of assessment of building …………………………..………….21
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Rapid Visual Screening of Himachal Pradesh
List of tables
1. Statistics of surveyed buildings in 6 districts of Himachal Pradesh ….…..……...19
2. Details of surveyed buildings typology wise ………………………………………19
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Rapid Visual Screening of Himachal Pradesh
Abstract
India faces serious earthquake problems by a rapid growth of urban population. Nearly
60% of landmass in India is under moderate to severe earthquake prone area. During
2001 Bhuj earthquake, massive damage was happened to moderate buildings.
Reconnaissance survey reports suggested that the need for seismic evaluation of
existing buildings. Different methods for seismic evaluation of existing buildings have
developed in various countries. Most of the methods follow three level assessment
procedures (or something quite similar to it) namely, (a) rapid visual screening, (b)
preliminary assessment, and (c) detailed evaluation.
Rapid Visual Screening (RVS) was conducted on 9099 buildings in Himachal Pradesh
state. In this study, five different typologies like Reinforced Concrete, Brick Masonry,
Stone Masonry, Hybrid and Rammed Earth buildings were selected. The RVS
methodology is referred to as 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 the building type, seismic zone, soil conditions, horizontal and
vertical irregularities, apparent quality in masonry and RC structures and short column
etc. This walk survey is carried out based on the checklists provided in a proforma for
all five typology of buildings. Other important data regarding the building is also
gathered during the screening, including the occupancy of the building and the
presence of nonstructural falling hazards. A performance score is calculated for the
building based on numerical values on the RVS form corresponding to these features.
The performance score is compared to a “cut-off” score to determine whether a building
has potential vulnerabilities that should be evaluated further by an experienced
engineer. Gaussian distribution is applied for cut off score in this study.
An attempt has been made to do rapid visual screening of five varieties of buildings in
Himachal Pradesh state. RVS score has calculated for 9099 buildings and plotted normal
distribution curves for each typology of building to understand the distribution of
buildings in HP state. From the study, it is clearly shown that Kangra district have more
buildings in all five different typologies.
As per statistics of surveyed buildings by TARU consultants in Himachal Pradesh,
around 17% (1541 out of 9099) of buildings are reinforced concrete, 48% (4363 out of
9099) of buildings are brick masonry, 15% (1341 out of 9099) of buildings are stone
masonry, 5% (518 out of 9099) of buildings are rammed earth and 15% (1318 out of
9099) of buildings are hybrid. However, there are some low RVS score buildings which
are potentially vulnerable to future earthquakes. Also it is suggested that preliminary
analysis needs to be performed on 47 buildings and detailed analysis for 15 buildings
for calibrating RVS scores.
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Rapid Visual Screening of Himachal Pradesh
1. Introduction
India faces serious earthquake problems by a rapid growth of urban population. Nearly
60% of landmass in India is under moderate to severe earthquake prone area. BiharNepal border (M6.4) in 1988, Uttarkashi, Uttaranchal (M6.6) in 1991, Latur, Maharastra
(M6.3) in 1993, Jabalpur, Madhya Pradesh (M6.0) in 1997, Chamoli, Uttaranchal (M6.8)
in 1999, Bhuj, Gujarat (Mw7.7) in 2001 and Muzzafarabad, Kashmir (M7.2) in 2005 and
Sikkim (M6.8) in 2011. These earthquakes caused around 2 lakh causalities. However,
similar high intensity earthquakes in the US, Japan, etc., do not lead to such an
enormous loss of lives, as the structures in these countries are earthquake resistant.
During 2001 Bhuj earthquake, massive damage was happened to moderate buildings.
Reconnaissance survey reports (Jain S. K, 2005) suggested that the need for seismic
evaluation of existing buildings. In India as well as worldwide RVS has been done for a
maximum of few hundred buildings. It is for the first time that the number like 16000
has done in the state of Gujarat (Srikanth et al, 2010). In this study, an attempt has been
made to do RVS for five different typologies like Reinforced Concrete, Brick Masonry,
Stone Masonry, Hybrid and Rammed Earth buildings. As per the Indian Standards
seismic zonation map, Himachal Pradesh state falls in Zone IV and V. And five districts,
namely Chamba, Hamirpur, Kangra, Kullu, Mandi have liable to the severest design
intensity of MSK IX or more, the remaining area of these districts are liable to the next
severe intensity VIII. Two districts, Bilaspur and Una have also substantial area in MSK
IX and rest in MSK VIII. The remaining districts also are liable to intensity VIII. Besides,
the earthquake, the people of HP have also affected by several natural hazards like
landslides, avalanches, floods, fires etc. Figure 1 shows district names to be surveyed in
Himachal Pradesh. Different methods for seismic evaluation of existing buildings have
developed in various countries. Most of the methods follow three level assessment
procedures (or something quite similar to it namely,
(a) Phase-I: Rapid visual screening,
(b) Phase-II: Preliminary assessment, and
(c) Phase-III: Detailed evaluation.
2. Vulnerability Studies of Cities
Vulnerability assessment of cities has been performed in the past based on population
loss estimation and estimation of direct and indirect losses due to various disasters
(Keya Mitra, 2008). The various methods for the vulnerability assessment of buildings
differ in time spent for each building and the degree of analysis that a building is
subjected to. Some recent vulnerability assessment studies are discussed in the
following sections:
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Rapid Visual Screening of Himachal Pradesh
Figure 1. Districts considered for RVS in Himachal Pradesh
2.1 Tehra, Iran
Seismic vulnerability assessment in the city of Tehran (Keya Mitra, 2008) was
done based on database collection and damage estimation for buildings for two
earthquake scenarios. A visual survey was carried out to identify the condition of
buildings and type of occupancy. Seismic building damage for earthquake
scenarios were derived from HAZUS software ranging from slight to complete
degree of damage. Most of the buildings in the study area were found to be
vulnerable considering the two earthquake scenarios. The recommendation of
the study was that to secure lives and property in the study area.
2.2 Dehradun, India
The vulnerability assessment in Uttaranchal was done by singh in 2005. This
study developed a methodology for loss estimation based on building and
population loss. A GIS based tool was developed for primarily population loss
estimation. The research was broadly concluded that in a predominantly
residential area, population distribution and census sources.
2.3 Basel, Switzerland
The evaluation of seismic vulnerability of existing residential building in the city
of Basel, Switzerland (Keya Mitra, 2008) was undertaken to improve the
assessment of seismic hazard, to investigate the vulnerability of the built
environment. Since no major damaging earthquake has occurred in Switzerland
in recent years, vulnerability functions from observed damage patterns were not
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Rapid Visual Screening of Himachal Pradesh
available. A simple evaluation method based on engineering models of the
building structures suitable for the evaluation of a larger number of buildings
was therefore proposed. The study concluded that it was not feasible to evaluate
each individual building in a large area, even though large number of buildings
could be evaluated in the study. Hence a classification of buildings was proposed
to allow the extrapolation of the results for the use of earthquake scenario.
2.4 Kanpur, India
Preliminary evaluation based on IITK-GSDMA guidelines were carried out on 30
representative multistoried RC buildings. The study revealed that large
openings, horizontal and vertical projections, presence of soft and weak storeys
and short column effects are major weaknesses in the buildings at Kanpur from
seismic safety point of view. This study concluded that strict enforcement
mechanisms for implementation of IS codes.
2.5 Zeytinburnu, Turkey
This study is an implementation of the earthquake master plan for Istanbul
metropolitan area in the Zeytinburnu district with a population of 240,000 and
more than 16,000 buildings (Keya Mitra, 2008). As a part of seismic vulnerability
of existing building, a multi stage seismic safety assessment was performed.
2.6 Gandhidham, India
Rapid Visual Screening (RVS) was conducted around 20,000 buildings in
Gandhidham and Adipur cities (Srikanth et.al, 2010). Though, construction
practices are varied, about 26% of buildings were predominantly RCC type and
74% of masonry structure were found. RVS score of these structures reveal that
in general buildings are of low quality and further evaluation and strengthening
of buildings is recommended. The procedure adopted in this study is three tier
method, i.e., rapid visual screening, preliminary assessment and detailed
assessment.
3. Literature on Vulnerability Assessment Methods
Most of the methods for seismic evaluation of building follow three levels of
assessment. RVS methods vary from those requiring 15-30 minutes on site for each
building to more detailed ones involving some basic calculations. Preliminary
assessment techniques are employed to analyze the building performance when a more
reliable assessment is required. This requires detailed information regarding the
structural components, material properties and site conditions. The in-depth evaluation
through sophisticated structural analysis falls within the third category of vulnerability
assessment. The worldwide practices are as follows:
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Rapid Visual Screening of Himachal Pradesh
3.1 International Practices in RVS
RVS can be very valuable to prioritize the buildings to be further studied so that
technical and other resources could be most effectively utilized. The procedure involves
side walk survey either without entering the building or doing so for a short duration
only (15-45 minutes). RVS is useful when the number of buildings to be evaluated is
large, since even non-engineers may collect data and assign scores. However,
uncertainty and non availability of the details can result in widely differing
interpretations of the criteria by different individuals leading to inconsistent results.
3.2 RVS Methodologies in the USA
A number of guidelines were developed by the federal emergency management
agency (FEMA) in the USA for seismic risk assessment and rehabilitation of buildings.
These includes FEMA 178(1992) published in 1989 and revised in 1992, FEMA 310(1998)
developed as revised version of FEMA 178, FEMA 154(2002) for rapid visual screening
of buildings. The RVS method was originally developed by the applied technology
council (ATC) in the late 1980s and published in 1988 in the FEMA 154 Report. FEMA
310 includes a process for seismic evaluation of existing buildings, with the introduction
of an analysis procedure for screening, preliminary evaluation and detailed evaluation.
3.3 FEMA 154
The basis of FEMA 154 is the ATC 13 report (ATC: 13-1988) on earthquake
damage evaluation data for facilities in California which includes background
information, detailed description of methodology used to develop the required
earthquake damage/loss estimates, inventory information and damage probability
matrices for different facility types and estimates as well as the time required to restore
damaged facilities to their pre-earthquake usability. These were developed by a project
engineering panel composed of senior level specialists in earthquake engineering.
a. FEMA: 154 -1988 (First edition)
In developing a handbook on rapid visual screening of seismically hazardous
buildings, ATC evaluated procedures, recommended a rapid screening procedure and
developed supplementary information on heavy debris removal and urban rescue. The
basic structural hazard scores in the first edition of FEMA 154 were calculated using (1)
expert-opinion damage probability matrices from the ATC-13 report, earthquake
damage evaluation data for California (ATC,1985) modified for use in regions outside
of California and (2) ground motion maps provided with the NEHRP recommended
provisions for the development of seismic regulations for new buildings (BSSC,1985),
which specified effective peak acceleration ground motion having a 10% probability of
being exceeded in 50 years.
FEMA: 155-2002, performance modification factors (PMF) developed in the first edition
were related to significant deviations from the normal structural practice or conditions,
or had to do with the effects of soil amplification on the expected ground motion.
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Rapid Visual Screening of Himachal Pradesh
Deviations from the normal structural practice are varied and numbers are quite large
for different building types. Many of these cannot be detected from the street on the
basis of a rapid visual inspection. On account of this, and based on querying of experts
and checklists from ATC 14, a limited number of most significant factors were
identified. These factors were limited to those having an especially severe impact on
seismic performance. Those that could not be readily observed from the street were
eliminated. The PMFs were assigned values, based on judgment, such that when
applied to the basic structural hazard scores, the resulting modified score would
approximate the probability of major damage given the presence of that factor. As
discussed in FEMA: 155-2002, the PMFs in the first edition were based on engineering
judgment, lacked analytically basis.
b. FEMA: 154 -2002 (Second edition)
Several significant changes and enhancements were incorporated in the second edition
of the FEMA 154 handbook as follows:
An updated scoring system, formatted as in the scoring system in the first edition and
consisting of
a. New Basic structural hazard scores based on (1) the HAZUS methodology and
fragility curves (NIBS,1999) for low rise buildings and assuming soil type B and (2)
new maximum considered earthquake seismic design spectral acceleration
response values (developed by the USGS and building seismic safety council),
which are based on ground motion having a 2% probability of being exceeded in
50 years, adjusted to incorporated the 2/3 reduction factor specified in the FEMA
319 handbook for the seismic evaluation of buildings-A pre standard (ASCE,1998);
and
b. Performance modification factors were renamed as score modifiers
c. New scores modifiers were proposed for mid rise building, high rise buildings, plan
irregularity, vertical irregularity, pre-code buildings, post-benchmark buildings, soil
type C, soil type D, soil type E. One of these modifiers was based on calculations to
reflect the HAZUS fragility curves and methodology. The vertical irregularity was left
to judgment.
A comparison between the performances score modifiers of FEMA and the earthquake
engineering building characteristics listed in ATC 13 (1985) reveals the rationale for the
judgment of practicing engineers that led to the performance modification factors in
FEMA 154 first edition and retained in the second edition (2002) with changes in the
numerical values of the same. These have been summarized in table 5.1. An important
change was in the score modifier in FEMA 1st Edition were less than zero implying
penalties. This was indicative of judgment of that time that the vulnerability of high rise
buildings to earthquakes was higher that low rise buildings. Hence, score modifiers for
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Rapid Visual Screening of Himachal Pradesh
the mid rise and high rise buildings is generally positive in the second edition
indicating advantages given for the better design and construction that these buildings
are likely to posses.
3.4 RVS in Greece
A fuzzy logic based rapid visual screening procedure was developed in Greece
(Demartinos and Dritsos, 2006) for the categorization of buildings into five different
damage grades in the event of future earthquake. The method was developed on 102
buildings affected by 1999 Athens earthquake. The above based RVS proposed a
probabilistic reasoning method that treats the structural properties of a building in a
holistic way and gives a score that represents possible damage in the case of major
seismic event, defined as earthquakes that produce ground accelerations equivalent to
the values provided by the relevant codes. The evaluation of output variables through
the fuzzy inference process involves the evaluation of all fuzzy rules that make up the
system. For the sake of simplification, the developers of this method have proposed
grouping of input variable to a set of four intermediate variables which are evaluated
through fuzzy inference processing of the input variables. The damage score is
evaluated through a fuzzy inference system. Higher damage scores indicate greater
vulnerability.
3.5 RVS in Canada
The method is based on a seismic priority index which accounts for both
structural and non-structural factors including soil conditions, building occupancy,
building importance and falling hazards to life safety and a factor based on occupied
density and the duration of occupancy.
3.6 RVS in Japan
The procedure is based on seismic index for total earthquake resisting capacity of
a storey which is estimated as the product of basic seismic index based on strength and
ductility indices, an irregularity index and time index. The evaluation is based on very
few parameters and lacks clarity regarding ranking of buildings based on a scoring or
rating system.
3.7 RVS in New Zealand
The New Zealand code recommends a two stage seismic performance evaluation
of buildings. The initial evaluation procedure involves making an initial assessment of
performance of existing buildings against the standard required for a new building. A
percentage new building standard of 33 or less means that the building is assessed as
“potentially earthquake prone” in terms of the building act and a more detailed
evaluation of it will typically be required. The process requires the expertise of
earthquake engineers to yield quality results.
3.8 RVS in India
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Rapid Visual Screening of Himachal Pradesh
There have been some efforts in India towards developing RVS methods. Sinha
and Goyal have proposed a methodology for RVS of 10 different types of buildings. The
procedure requires identification of the primary structural load carrying system and
building attributes that are expected to modify the expected seismic performance for the
lateral load resisting system under consideration. Building types have grouped into six
vulnerable classes based on European Macro seismic scale (EMS) recommendations.
Likely damage to structures have been categorized in different grades depending on
their impact on the seismic strength of buildings and the damage levels used have been
sourced from EMS.
4. Methodology
A schematic diagram of assessing of any building is shown in figure 2. The evaluation is
based on a few parameters of buildings. The parameters of the buildings 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) + ∑[(VSM) x (VS)]
Where VSM represents the Vulnerability Score Modifiers and VS represents the
Vulnerability Score that is multiplied with VSM to obtain the actual modifier to be
applied to the BS or Basic Score.
The data analysis of the existing buildings in the region is scrutinized on the basis of
Gaussian (Normal) distribution. This distribution is commonly used for statistical
analysis of large data. A normal distribution in a variate X with mean µ and variance σ
is a statistical distribution with probability density function:
f (x) 

1
 2
x   
e
2 2
Generally a cumulative probability refers to the probability that the value of a random
variable falls within a specified range. Frequently, cumulative probabilities refer to the
probability that a random variable is less than or equal to a specified value. The
cumulative Distribution function, which gives the probability that a variate will assume
a value ≤x, is then
D(x ) 
x


P(x )dx 
1
 2
13
x
e

( x   )
2 2
dx
Rapid Visual Screening of Himachal Pradesh
From these two it is very convenient to represent the probability that the performance
score is less than or equal to some specified values under the curve.
Based on the scores of RVS, some percentage of structures will be selected for
preliminary evaluation and further for detailed evaluation. RVS is useful when the
number of buildings to be evaluated is large. In this survey, even non-engineers may
collect data and assign scores. Finally correlation between three phases will be
standardized for further application of seismic evaluation in other cities falling in zone
IV and V of seismic zoning map of India. Based upon this complete evaluation we can
develop strategies for both short-term and long-term mitigation and plans to reduce
risk in different areas.
Figure 2. Schematic diagram of assessment of building
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Rapid Visual Screening of Himachal Pradesh
4.1 Phase-I: Rapid visual screening
In this project, an attempt has been made to survey 9099 building in Himachal Pradesh.
The above buildings include five varieties of buildings namely, brick masonry,
reinforced concrete, hybrid, stone masonry and rammed earth buildings. As a part of
this project, RVS forms are generated for stone, hybrid and rammed earth buildings.
RVS scores have calculated for the above buildings. A proforma of RVS sheet for all five
building
s
are
shown
in figure
3 to 7.
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Rapid Visual Screening of Himachal Pradesh
Figure 3 (a). Proforma for Brick Masonry Buildings (First page)
Figure 3 (b). Proforma for Brick Masonry Buildings (Second page)
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Rapid Visual Screening of Himachal Pradesh
Figure 4 (a). Proforma for Hybrid Buildings (First page)
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Rapid Visual Screening of Himachal Pradesh
Figure 4 (b). Proforma for Hybrid Buildings (Second page)
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Rapid Visual Screening of Himachal Pradesh
Figure 5 (a). Proforma for Reinforced Concrete Buildings (First page)
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Rapid Visual Screening of Himachal Pradesh
Figure 5 (b). Proforma for Reinforced Concrete Buildings (Second page)
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Rapid Visual Screening of Himachal Pradesh
Figure 6 (a). Proforma for Rammed Earth Buildings (First page)
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Rapid Visual Screening of Himachal Pradesh
Figure 6 (b). Proforma for Rammed Earth Buildings (Second page)
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Rapid Visual Screening of Himachal Pradesh
Figure 7 (a). Proforma for Stone Masonry Buildings (First page)
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Rapid Visual Screening of Himachal Pradesh
Figure 7 (b). Proforma for Stone Masonry Buildings (Second page)
This performance score mainly depends on soil type, building condition, architectural
and earthquake resistance features. Other important data regarding the building is also
gathered during the screening, including the occupancy of the building and the
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Rapid Visual Screening of Himachal Pradesh
presence of nonstructural falling hazards. In this, nonstructural interior components are
not evaluated. The performance score is compared to a “cut-off” score to determine
whether a building has potential vulnerabilities that should be evaluated further by an
experienced engineer. From these scores, we can come to a conclusion on whether the
building strength is adequate for earthquake forces likely to occur at the site.
Many different types of damage can occur in buildings. Damage can be divided into
two categories: structural and nonstructural, both of which can be hazardous to
building occupants. Structural damage means degradation of building’s structural
support systems (i.e. vertical and lateral force resisting systems), such as the building
frames and walls. Nonstructural damage refers to any damage that does not affect the
integrity of the structural support systems. Examples of nonstructural damage are
chimneys collapsing, windows breaking, or ceilings falling. The type of damage to be
exposed is a complex issue that depends on the structural type and age of the building,
its configuration, construction materials, the site conditions, the proximity of the
building to neighboring buildings, and the type of non structural elements. Structural
parameters that have to be observed during the field surveys and the value given to
each parameter by the observer are briefly given below.
4.1.1 Brick Masonry Buildings
The basic components of masonry buildings are roofs, floor slabs, walls and
foundations (spread wall footings). The walls and footings are mainly made of bricks or
stones, laid in horizontal courses, with mortar filling up the gaps and providing the
required bond between the units. Figure 8 shows typical view of brick masonry
building.
Figure 8. Typical view of brick masonry building
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Rapid Visual Screening of Himachal Pradesh
4.1.2 Reinforced Concrete Structures
In a framed building, the basic skeleton (frames) comprises of beams, columns and
footings (fig. 9). The framework resists both vertical and lateral loads. Reinforced
concrete is comprised of two basic materials, steel and concrete. The two materials work
in a synergistic fashion when constructed properly to provide composite components
which have very strong structural characteristics. Reinforced concrete is commonly
used in structures designed for heavy use and long life, such as governmental and
institutional buildings and public works structures. Concrete has a great capacity to
support compressive loads. Steel has a great capacity to carry both compressive and
tensile loads. Beams are horizontal structural components that support floors, ceilings,
roofs, or decks (i.e., bridge and parking decks). The loads carried by a beam are
primarily perpendicular to the longitudinal axis of the beam. A typical reinforced
concrete beam is designed to allow the compressive forces to be carried by the concrete
material and the tensile forces to be carried by the steel. Columns are vertical structural
components that support beams and other structural elements. The compressive loads
carried by columns are primarily parallel to the vertical or longitudinal axis of the
column.
Figure 9. Typical view of RC building
4.1.3 Year of Construction
In India, reinforced concrete structures are designed and detailed as per the Indian
Code IS:456-2000. It was revised in year 2000 and IS:1893 code is revised in year 2002.
Most of the buildings satisfy gravity and serviceability loads only. However, structures
located in high seismic regions require ductile design and detailing. Provisions for the
ductile detailing of monolithic reinforced concrete frame and shear wall structures
are specified in IS:13920-1993. After the 2001 Bhuj earthquake, this code has been
made mandatory for all structures in zones III, IV and V. Newer buildings
generally sustain less damage than older buildings designed to earlier codes.
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Rapid Visual Screening of Himachal Pradesh
4.1.4 Number of Floors
This is the total number of floors above the ground level. The buildings were generally
residential, although some were commercial and some mixed use involving residential
accommodation above ground floor commercial premises.
4.1.5 Structural Irregularities
Properly distributed lateral load resisting elements within the building lead to a regular
structural configuration and better seismic performance. The structural walls should be
uniformly distributed in both orthogonal directions of the building. They should be
sufficient in number and strong enough to resist the expected seismic loads. In masonry
buildings, horizontal vibrations can be most damaging, especially in situations where
adequate walls are not present in both the orthogonal directions, or when the walls are
not properly joined to adjacent walls. In low income residential areas, having small and
narrow plots the houses may have two parallel walls in one direction only, with fewer
walls in the perpendicular direction. In deep plots located in commercial areas, with
comparatively narrow frontages, it is quite common in India to find buildings with
walls only at the two ends along the long directions and no walls in the other direction,
to accommodate clear floor space for display or storage. Such buildings are clearly very
vulnerable. Figure 10 shows presence of structural irregularities in the building.
Figure 10. Structural irregularities are present in the building at Kangra district
4.1.6 Heavy Overhangs
Heavy overhangs are formed when projections of the actual habitable spaces, from the
first floor upwards, are made to increase the available floor area in the upper floor
27
Rapid Visual Screening of Himachal Pradesh
tenements. Buildings having such large and heavy cantilever projections have been
observed to sustain heavy damage in earthquake events. Heavy balconies and
overhanging floors in multistory reinforced concrete buildings shift the mass center
upwards; accordingly give rise to increased seismic lateral forces and overturning
moments during earthquakes. Heavy balconies and overhanging floors in reinforced
concrete buildings shift the mass center upwards; accordingly increase seismic lateral
forces and overturning moments during earthquakes. Buildings having balconies with
large overhanging cantilever spans enclosed with heavy concrete parapets sustained
heavier damages during the earthquakes compared to regular buildings in elevation.
Since this building feature can easily be observed during a walk-down survey, it is
included in the parameter set. Large cantilevers (projections supported only on one
side) especially at upper floors are undesirable. Figure 11 shows presence of heavy
overhangs on the top of building.
Figure 11. Heavy overhangs are present on the top of structure at Kangra district
4.1.7 Re-entrant Corners
The re-entrant, lack of continuity or “inside” corner (fig. 10) is the common
characteristic of overall building configuration that, in plan, assume the shape of an L,
T, H, +, or combination of these shapes. The dimension of the offset and the proportion
of the derived wings will determine the vulnerability of a building. Each wing will react
to the displacements and the torsional effects produced by ground motions in a
different way. Under the action of earthquake forces, each wing will have a different
dynamic behavior because of its particular stiffness and position relative to the direction
of horizontal forces. The movement of different parts of the building can be very
complicated, producing considerable diaphragm deformation, torsional effects and
concentration of stress at the vertices of reentrant corners.
28
Rapid Visual Screening of Himachal Pradesh
Figure 10. Re-entrant corners in buildings
4.1.8 Local Soil Conditions
The intensity of ground motion at a particular site predominantly depends on the
distance the causative fault and local soil conditions. There exists a strong correlation
between Peak Ground Velocity (PGV) and the shear wave velocities of local soils. Site
amplification is one of the major factors that increase the intensity of ground motions.
Although it is difficult to obtain precise data during a street survey, an expert observer
could be able to classify the local soils as stiff or soft. The geotechnical data provided by
local authorities is a reliable source for classifying the local soil conditions. The risk of
building increases, as the softness of soil increases. If the soil is sandy and is saturated
with ground water, there is a possibility of liquefaction during earthquakes as the soil
loses its firmness and behaves as a jelly.
4.1.9 Pounding
Pounding is damage caused by two buildings, or different parts of a building, hitting
one another. The number of buildings damaged by pounding is small. Pounding is the
result of irregular response of adjacent buildings of different heights and of different
dynamic characteristics. In situations where two buildings are located too close to each
other, they may collide during strong shaking leading to substantial damage. The
pounding effect is more pronounced in taller buildings (fig. 12). When building heights
do not match, the roof of the shorter building may pound at the mid-height of the
columns in the taller building; this can be quite dangerous, and can lead to story
collapse.
29
Rapid Visual Screening of Himachal Pradesh
Figure 12. Possible location of occurrence of pounding
4.1.10 Diaphragm Action
The diaphragm configuration is the shape and arrangement of horizontal resistance
elements that transfer forces between vertical resistance elements. Diaphragms perform
a crucial role in distributing forces to the vertical seismic resisting elements. The
diaphragm acts as a horizontal beam, and its edges act as flanges. Geometrical
irregularities are analogous to such irregularities in other building elements, leading to
torsion and stress concentration. The horizontal inertia forces generated by the ground
motion at different locations of the floor must be transferred to the vertical elements
such as walls. For this, the floor must act as a diaphragm. Cast-in-situ reinforced
concrete or reinforced brick slabs are quite effective as diaphragms. However, other
types of floors such as timber, if not properly connected together, for seismic loading,
may not provide the diaphragm action. Discontinuities in the diaphragm due to the
presence of large cut outs hinder the ability of the diaphragm to transfer lateral forces to
the walls. Diaphragms cannot be determined from building exteriors during rapid
visual screening surveys and may be observed only if access to a building is possible.
The same is true of cut outs in diaphragms. Considering the importance of proper
diaphragm action in the seismic performance of buildings, a penalty modifier of -10 is
proposed in situations where absence of proper diaphragm action can be confirmed. No
modifiers are proposed for situations where diaphragm action is either present or
undeterminable through visual screening alone.
4.1.11 Soft/weak stories
A soft or weak storey is created when the lateral stiffness and/or strength of a storey is
markedly more flexible than the floors above and below. This often occurs at the
30
Rapid Visual Screening of Himachal Pradesh
ground floor when it is left open for parking, a shop front, or other reasons. Most of the
deformation demand from the seismic event is concentrated at this level and results in
large rotation demand in columns that have not been designed for ductility. Soft/weak
storey collapses have been seen in many past earthquakes. Soft story usually exists in a
building when the ground story has less stiffness and strength compared to the upper
stories. This situation mostly arises in buildings located along the side of a main street.
The ground stories, which have level access from the street, are employed as a street
side store or a commercial space whereas residences occupy the upper stories. These
upper stories benefit from the additional stiffness and strength provided by many
partition walls, but the commercial space at the bottom is mostly left open between the
frame members, for customer circulation. Besides, the ground stories may have taller
clearances and a different axis system causing irregularity. The compound effect of all
these negative features from the earthquake engineering perspective is identified as a
soft story. Many buildings with soft stories were observed to collapse due to soft story
in the past earthquakes all over the world.
4.1.12 Short Column Failure
A short column failure is caused by its relatively high stiffness in comparison to other
columns at that floor level. The transverse forces generated at a floor level are
distributed in proportion to the member stiffness, therefore a short column will attract a
greater proportion of the load and, when compared to a more slender member, will
have less ability to withstand the deflections that will occur over their height. Frames
with partial infill lead to the formation of short columns which sustain heavy damage
since they are not designed for the high shear forces due to shortened heights that will
result from a strong earthquake. Semi-in-filled frames, band windows at the semiburied basements or mid-story beams around stairway shafts lead to the formation of
short columns in concrete buildings. These captive columns usually sustain heavy
damage during strong earthquakes since they are not originally designed to receive the
high shear forces relevant to their shortened lengths. Short columns can be identified
from outside because they usually form along the exterior axes.
4.1.13 Frame Action
Load transfer means to support the loads acting on the building and to safely carry
them down to the soil below. In a framed building, the loads are transferred by 'Frame
Action'. First the loads are transferred from slabs to beams. Beams then transfer them to
columns immediately below them. These columns transfer the loads to lower columns.
While a beam carries the load for that floor only, a column carries the load for all the
floors above it. The lowermost columns transfer the loads to the foundation, which, in
turn, transfers them to the soil.
4.1.14 Falling Hazards
Presence of various non-structural components such as air conditioning units, parapets
and advertisement hoardings can cause injury to pedestrians as well as to building
31
Rapid Visual Screening of Himachal Pradesh
occupants and contents during an earthquake, even though these may not have
implications for the overall structural safety of the building. These are important
because they can and do contribute to earthquake related losses as is evident from
instances of chemical spills, breakage to building contents, misalignment of piping, etc.
Falling hazards include mechanical and electrical equipment, piping and ducting,
unsecured masonry parapets, and eccentrically placed water tanks on top of the
building. A slab or a beam supported only on one side and projecting horizontally on
the other side is called a 'Cantilever' slab or beam e.g. balconies, lofts and canopies.
Figure 13 shows location of falling hazards in a building.
Figure 13. Falling hazards in a building
4.2 Phase-II: Preliminary Evaluation
Preliminary evaluation methodology is applied when in-depth evaluation of buildings
stock is required. In this stage, simplified analysis of the building under investigation is
performed based on a variety of methods.
This phase involves the following tasks:




Collection of drawings and redraw (if possible) in AutoCAD,
Identification of the sizes of all columns and beams,
Load calculations,
Configuration related checks and strength related checks.
32
Rapid Visual Screening of Himachal Pradesh
Phase-II can broadly classified into two categories, (a) configuration-related and (b)
strength related checks. The first tier involves a quick assessment of the earthquake
resistance of the building and its potential deficiencies, with the objective to screen out
the significantly vulnerable structures for the second tier detailed analysis and
evaluation. The first tier evaluation typically consists of assessing the configurationally
induced deficiencies known for unsatisfactory performance along with a few global
level strength checks, whereas the next level of evaluation consists of proper force and
displacement analysis to assess structural performance at both global and/or
component level.
Configuration related checks:
Although a building with an irregular configuration may be designed to meet all code
requirements, irregular buildings generally do not perform as well as regular buildings
in an earthquake. Typical building configuration deficiencies include an irregular
geometry, a weakness in a given story, a concentration of mass, or a discontinuity in the
lateral force resisting system. Vertical irregularities are defined in terms of strength,
stiffness, geometry and mass. Horizontal irregularities involve the horizontal
distribution of lateral forces to the resisting frames or shear walls.
Load Path:
Inertial forces, induced as a result of the seismic force effects from any horizontal
direction, are transferred from the mass to the foundation through the load path. If
there is a discontinuity in the load path, the building is unable to resist seismic forces
regardless of the strength of the existing elements.
Weak Story:
The story strength is the total strength of all the lateral force-resisting elements in a
given story for the direction under consideration. Weak stories are usually found where
vertical discontinuities exist, or where member size or reinforcement has been reduced.
The result of a weak story is a concentration of inelastic activity that may result in the
partial or total collapse of the story.
Soft Story:
Soft story condition commonly occurs in buildings with open fronts at ground floor or
with particularly tall first stories. Soft stories usually are revealed by an abrupt change
in interstory drift.
Effective Mass:
33
Rapid Visual Screening of Himachal Pradesh
Mass irregularities can be detected by comparison of the story weights. The effective
mass consists of the dead load of the structure tributary to each level, plus the actual
weights of partitions and permanent equipment at each floor. Mass irregularities affect
the dynamic response of the structure, and may lead to unexpected higher mode effects
and concentrations of demand.
Torsion:
Whenever there is significant torsion in a building, the concern is for additional seismic
demands and lateral drifts imposed on the vertical elements by rotation of the
diaphragm. Buildings can be designed to meet code forces including torsion, but
buildings with severe torsion are less likely to perform well in earthquakes.
Strength Related Checks:
The seismic evaluation documents specify some global level checks to quickly identify
the major deficiencies. At the global level, buildings are mainly checked for shear stress
and axial stress.
4.3 Phase-III: Detailed Evaluation
It requires linear or nonlinear analyses of the building based on as-built dimensions.
This phase involves the following tasks:
 Calculation of vertical distribution of lateral forces by static method,
 Eccentricity calculation for additional torsional moment,
 Component level analysis of calculation of moment of resistance in hogging &
sagging,
 Check for shear capacity of beam, column flexural capacity, strong column weak
beam considerations, storey drift of the frame.
Lastly, correlation will be drawn based on detailed evaluation and RVS score.
5. Seismicity of Himachal Pradesh
Himachal Pradesh is located 31.1033° N, 77.1722° E and lies in the Himalayan
Mountains, and is part of the Punjab Himalayas. Large earthquakes have occurred in all
parts of Himachal Pradesh, the biggest being the Kangra Earthquake of 1905. The
Himalayan Frontal Thrust, the Main boundary Thrust, the Krol, the Giri, Jutogh and
Nahan thrusts lie in this region. However, it must be stated that proximity to faults does
not necessarily translate into a higher hazard as compared to areas located further
34
Rapid Visual Screening of Himachal Pradesh
away, as damage from earthquakes depends on numerous factors such as subsurface
geology as well as adherence to the building codes. Chamba, Kullu, Kangra, Una,
Hamirpur, Mandi, and Bilaspur Districts lie in Zone V. The remaining districts of
Lahual and Spiti, Kinnaur, Shimla, Solan and Sirmaur lie in Zone IV. Since the
earthquake database in India is still incomplete, especially with regards to earthquakes
prior to the historical period (before 1800 A.D.). The largest instrumented earthquake in
Himachal Pradesh was 1905 Kangra earthquake (Mw7.8). The seismicity and faults map
of Himachal Pradesh is shown in figure 14.
6. Case study in Himachal Pradesh
In this project, an attempt has been made to survey 9099 building in Himachal Pradesh.
The above buildings include five varieties of buildings namely, brick masonry,
reinforced concrete, hybrid, stone masonry and rammed earth buildings. The location of
buildings considered in this analysis shown in figure 15. For each typology, RVS score
is calculated from the above relations (Ref. section 4). From total number of buildings,
the number of different typologies is as follows:
 Reinforced Concrete Buildings: 1541
 Brick Masonry Buildings: 4363
 Stone Masonry Buildings: 1341
 Rammed Earth Buildings: 518
 Hybrid Buildings: 1318
35
Rapid Visual Screening of Himachal Pradesh
Figure 14. Seismicity and location of faults in Himachal Pradesh state
Figure 15. Location of buildings considered in the analysis
The number of buildings surveyed in the districts of Bilaspur, Hamirpur, Kinnaur,
Kullu, Lahul Spiti, Simla, Solan, Chamba, Kangra, Mandi, Sirmur and Una are 383, 789,
149, 619, 70, 401, 1553, 513, 1929, 692, 585, 637 respectively. The categorization of
buildings according to district and status wise are shown in figure 16-31.
36
Rapid Visual Screening of Himachal Pradesh
Types of Construction
No of Buildings
1500
1000
500
Una
Solan
Sirmur
Shimla
Mandi
Lahul
0
Brick Masonry
Hybrid
Rammed Earth
RC Frame
Stone Masonry
Types of Construction
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Figure 16. Statistics of type of construction for 12 districts in HP state
No of Buildings
Quality of Maintenance
2000
Una
Solan
Sirmur
Shimla
Mandi
1000
0
Not Undertaken
Undertaken
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Lahul
Quality of Maintenance
Figure 17. Statistics of quality of maintenance for 12 districts in HP state
37
Rapid Visual Screening of Himachal Pradesh
Age of Buildings
No of Buildings
600
400
200
0
Solan
Sirmur
0-10
10-20
20-30
30-40
40-50
Simla
Mandi
Kullu
Kangra
Hamirpur
Chamba
Bilaspur
>50
Age
Una
Districts
Figure 18. Statistics of age of buildings for 10 districts in HP state
Soil Types
No of Buildings
2000
1000
Una
Solan
Sirmur
Shimla
0
Mandi
Hard
Medium
Soft
Not Sure
Soil Types
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Figure 19. Statistics of type of soil conditions for 12 districts in HP state
38
Rapid Visual Screening of Himachal Pradesh
No of Buildings
Presence of Pounding
2000
1000
0
Does not Exist
Exists
Lahul
Una
Solan
Sirmur
Shimla
Mandi
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Presence of Pounding
Figure 20. Statistics of effect of pounding for 12 districts in HP state
No of Buildings
Corner Openings
1000
Una
500
Solan
Sirmur
Shimla
0
Does not Exist
Exists
Not Sure
Corner Openings
Mandi
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Figure 21. Statistics of corner openings for 12 districts in HP state
39
Rapid Visual Screening of Himachal Pradesh
No of Buildings
Substantial openings
1000
500
Solan
Sirmur
Simla
0
Mandi
Kullu
Kangra
Hamirpur
Chamba
Bilaspur
Does not Exist
Exists
Not Sure
Substantial openings
Districts
Una
Figure 22. Statistics of substantial openings for 10 districts in HP state
No of Buildings
Diaphragm Openings
2000
1000
0
Does not Exist
Exists
Lahul
Solan
Sirmur
Shimla
Mandi
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Diaphragm Openings
Figure 23. Statistics of diaphragm action for 12 districts in HP state
40
Una
Rapid Visual Screening of Himachal Pradesh
No of Buildings
Horizontal Bands
1000
Una
500
Solan
Sirmur
Shimla
0
Mandi
Lahul
Exists
Does not Exist
Not Sure
Horizontal Bands
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Figure 24. Statistics of horizontal bands for 12 districts in HP state
No of Buildings
Soft Storey
Una
2000
Solan
Sirmur
1000
Shimla
Mandi
0
Exists
Does not Exist
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Soft Storey
Figure 25. Statistics of soft storeys for 12 districts in HP state
41
Rapid Visual Screening of Himachal Pradesh
No of Buildings
Heavy Overhangs
Una
2000
Solan
Sirmur
Shimla
1000
Mandi
0
Exists
Does not Exist
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Heavy Overhangs
Figure 26. Statistics of heavy overhangs for 12 districts in HP state
No of Buildings
Short Column
Una
2000
Solan
Sirmur
Shimla
1000
Mandi
0
Exists
Does not Exist
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Short Column
Figure 27. Statistics of short columns for 12 districts in HP state
42
Rapid Visual Screening of Himachal Pradesh
Slope
No of Buildings
2000
1000
Una
Solan
Sirmur
Shimla
0
Mandi
Flat to Mild
Medium
Steep
Not Sure
Slope
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Figure 28. Statistics of buildings on slopes for 12 districts in HP state
No of Buildings
Staircase
Una
2000
Solan
Sirmur
1000
Shimla
Mandi
0
Exist
Does not Exist
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Staircase
Figure 29. Statistics of existance of staircase in buildings for 12 districts in HP state
43
Rapid Visual Screening of Himachal Pradesh
No of Buildings
Quality of Construction
1000
500
0
Good
Moderate
Poor
Quality of Construction
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Districts
Bilaspur
Lahul
Una
Solan
Sirmur
Shimla
Mandi
Figure 30. Statistics of construction quality for 12 districts in HP state
Types of Cracks
No of Buildings
800
600
400
200
0
Horizontal
Vertical
Diagonal
Horz & Diag
Horz & Vert
Horz, Vert & Diag
Vert & Diag
No Cracks
Types of Cracks
Una
Solan
Sirmur
Shimla
Mandi
Lahul
Kullu
Kinnaur
Kangra
Hamirpur
Chamba
Bilaspur
Districts
Figure 31. Statistics of different type of cracks for 12 districts in HP state
44
Rapid Visual Screening of Himachal Pradesh
In second stage, normal distribution curves are generated for different typology of
buildings. In this project, a total of 9099 buildings are surveyed in Himachal Pradesh.
The above buildings include five varieties of buildings namely, brick masonry,
reinforced concrete, hybrid, stone masonry and rammed earth buildings. RVS scores
have calculated for the above buildings. For brick masonry buildings the score ranges
from 40 to 220 for 4141 buildings. For reinforced concrete buildings the score ranges
from 50 to 160 for 1466 buildings. For hybrid buildings the score ranges from 60 to 140
for 1180 buildings. For stone masonry buildings the score ranges from 30 to 170 for 1042
buildings. For rammed earth buildings the score ranges from 50 to 150 for 509
buildings. The state Himachal Pradesh contains 12 districts namely, Bilaspur, Chamba,
Hamirpur, Kangra, Kullu, Mandi, Simla, Sirmur, Solan, Una, Lahul Spitti, and Kinnaur.
From the above data, RVS score is calculated for each district in Himachal Pradesh and
plotted in QGIS. Normal distribution curves are generated based on available RVS
scores. The normal distribution curves for total buildings as per district wise are shown
in figure 32-37. From the above studies, it is clearly shown that all typology of buildings
are available in the district of Kangra.
 Reinforced concrete buildings:
From the study, the number of RC buildings is more in Kangra district. The normal
distribution curves are wider for almost every district. Except Bilaspur district, the
number of RC buildings is few in other districts. The mean of RVS score of all districts
ranges from 100-110.
 Brick Masonry buildings:
From the study, the number of brick masonry buildings is more in Bilaspur, Kangra,
Una, Sirmur, Mandi and Hamirpur. The number of buildings present in these districts
is more than 100. Few buildings are present in the rest of districts. The mean of RVS
score of all districts ranges from 100-130. From the observation, brick masonry
buildings are evenly distributed throughout the state.
 Stone Masonry buildings:
From the study, the number of stone masonry buildings is more in Kangra district. The
normal distribution curves are wider for almost every district. Since the state is located
in hilly terrain, stone masonry buildings are constructed in every district. The mean of
RVS score of all districts ranges from 90-115.
 Rammed earth buildings:
From the study, the number of rammed earth buildings is more in Kangra district. The
normal distribution curves are wider for almost every district. Except Kangra district,
the number of rammed earth buildings is few in other districts. The mean of RVS score
of all districts ranges from 95-115.
45
Rapid Visual Screening of Himachal Pradesh
 Hybrid buildings:
From the study, the number of hybrid buildings is more in Kangra district. Since the
normal distribution curve is narrow for Kangra district, the RVS score ranges from 60 to
140. Except Kangra, and Una, the distribution curve is wider for rest of districts. The
mean of RVS score of all districts ranges from 100-110.
450
Bilaspur
Chamba
Hamirpur
Kangra
Kullu
Mandi
Shimla
Sirmur
Solan
Una
400
No. of Buildings
350
300
250
200
150
100
50
0
0
50
100
150
RVS Score
200
250
Figure 32. Normal distribution curve for brick masonry buildings through RVS
46
Rapid Visual Screening of Himachal Pradesh
250
No. of Hybrid Buildings
200
150
100
50
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
0
40
60
80
100
RVS Score
120
140
160
Figure 33. Normal distribution curve for Hybrid buildings through RVS
300
No. of Rammed Buildings
250
200
150
Chamba
Hamirpur
Kangra
Kullu
Mandi
Sirmur
Solan
Una
100
50
0
20
40
60
80
100
120
RVS Score
140
160
180
Figure 34. Normal distribution curve for Rammed earth buildings through RVS
47
Rapid Visual Screening of Himachal Pradesh
200
Bilaspur
Chamba
Hamirpur
Kangra
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
No. of RC Buildings
150
100
50
0
0
50
100
RVS Score
150
200
Figure 35. Normal distribution curve for RC buildings through RVS
140
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
No. of Stone Buildings
120
100
80
60
40
20
0
0
50
100
RVS Score
48
150
200
Rapid Visual Screening of Himachal Pradesh
Figure 36. Normal distribution curve for Stone Masonry buildings through RVS
1800
RC
Brick
Stone
Rammed
Hybrid
1600
No. of Buildings
1400
1200
1000
800
600
400
200
0
40
60
80
100
120
140
RVS Score
160
180
200
Figure 37. Normal distribution curve typology wise
International Institute of Information Technology with collaboration of Taru
consultancy has done survey on 47 buildings in Hamirpur, Kangra, Una, Mandi, Shimla
and Sirmur districts of Himachal Pradesh state. For preliminary analysis, around 15
buildings are taken for further analysis. The summary of buildings surveyed is shown
in table 1 and 2. The main criteria of selection of buildings are as follows:
 RVS score: The RVS score for all typology buildings is calculated from RVS forms
specified in appendix A. The buildings are selected based on low, medium and high
RVS scores.
 No. of storeys: The number of storeys varies from single storey to four storey.
 Unsymmetry: Building unsymmetry is also one of the factors which are considered
in the analysis. Around 5 asymmetric buildings are taken for analysis.
49
Rapid Visual Screening of Himachal Pradesh
Table 1. Statistics of surveyed buildings in 6 districts of Himachal Pradesh
S. No
District
RC
BM
Hybrid
Stone
Traditional
Total
1
2
3
4
5
6
7
Hamirpur
Kangra
Una
Mandi
Shimla
Sirmur
Total
4
2
2
3
4
3
18
3
5
3
2
5
2
20
1
1
1
1
4
2
2
2
1
3
8
12
5
5
11
6
S. No
1
2
3
Table 2. Details of surveyed buildings typology wise
No. of
District
Building Type
Storeys
Brick Masonry
2 + Steel
Brick Masonry
2
Brick Masonry
1
Reinforced Concrete
2
Hamirpur
(Seismic zone IV)
Reinforced Concrete
3
Reinforced Concrete
3
Reinforced Concrete
2
Hybrid
1
Brick Masonry
1
Brick Masonry
1
Brick Masonry
2
Brick Masonry
1
Brick Masonry
1
Reinforced Concrete
3
Kangra
(Seismic zone V)
Reinforced Concrete
3
Hybrid
2
Stone Masonry
2
Stone Masonry
1
Rammed Earth
2
Rammed Earth
2
Brick Masonry
1
Brick Masonry
2
Una
Brick Masonry
2
(Seismic zone IV)
Reinforced Concrete
2
Reinforced Concrete
1
50
RVS
Score
113
110
83
125
83
103
115
118
85
83
83
105
85
96
70
95
90
112
85
95
105
123
113
100
100
Rapid Visual Screening of Himachal Pradesh
4
Mandi
(Seismic zone V)
5
Shimla
(Seismic zone IV)
6
Sirmaur
(Seismic zone IV)
Brick Masonry
Brick Masonry
Reinforced Concrete
Reinforced Concrete
Reinforced Concrete
Brick Masonry
Brick Masonry
Brick Masonry
Brick Masonry
Brick Masonry
Reinforced Concrete
Reinforced Concrete
Reinforced Concrete
Reinforced Concrete
Hybrid
Rammed Earth
Brick Masonry
Brick Masonry
Reinforced Concrete
Reinforced Concrete
Reinforced Concrete
Hybrid
3
1
3
4
2
2
4
1+truss
2
2+truss
3
5
1+truss
2
2+truss
Truss
3
2
3
5+roof
3
4
52
85
61
55
95
85
35
105
105
82
105
75
135
115
105
120
125
105
86
90
106
120
Usually conclusions can be drawn based on the scores and Gaussian Normal
Distribution. It can be said that the buildings with higher performance scores perform
better compared to lower performance scores shall get damaged. However the
buildings which are in the middle range of performance score is large in number and
drawing meaningful conclusion is a difficult task because of non-availability of
standard results for the Indian conditions.
To overcome the above difficulty, it is proposed to do the preliminary assessment of
selected buildings. For this purpose around 50 buildings falling in the range of mean
plus or minus standard deviation are selected. Later detailed analysis is required on
selected few buildings to standardize the RVS score. After standardization of the
performance scores, the fragility curves will be prepared. The fragility curve is the
graph between seismic ground acceleration in ‘g’ and damage. This relationship will
estimate loss for different categories of buildings and intensities of earthquakes.
The normal distribution curves are drawn for all typology of buildings in the state of
Himachal Pradesh. The database of buildings for Himachal Pradesh is provided by
TARU Consultants Ltd. The total number of buildings present in the state is as follows:
51
Rapid Visual Screening of Himachal Pradesh
Reinforced Concrete Buildings: 8,426
Brick Masonry Buildings: 4,39,889
Stone Masonry Buildings: 3,29,911
Rammed Earth Buildings: 2,16,916
Hybrid Buildings: 32,646
Total Number of Buildings: 1027788
The normal distribution curves for the state of HP are shown in figure 38-43.
600
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
No. of Buildings
500
400
300
200
100
0
0
50
100
RVS Score
150
Figure 38. Normal distribution curve for RC buildings
52
200
Rapid Visual Screening of Himachal Pradesh
7
x 10
4
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
6
No. of Buildings
5
4
3
2
1
0
0
50
100
150
RVS Score
200
250
Figure 39. Normal distribution curve for Brick buildings
9
x 10
4
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
8
No. of Buildings
7
6
5
4
3
2
1
0
0
50
100
RVS Score
150
200
Figure 40. Normal distribution curve for Stone buildings
53
Rapid Visual Screening of Himachal Pradesh
12
x 10
4
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
No. of Buildings
10
8
6
4
2
0
20
40
60
80
100
120
RVS Score
140
160
180
Figure 41. Normal distribution curve for Rammed Earth buildings
10000
Bilaspur
Chamba
Hamirpur
Kangra
Kinnaur
Kullu
Lahul
Mandi
Shimla
Sirmur
Solan
Una
No. of Buildings
8000
6000
4000
2000
0
40
60
80
100
RVS Score
120
140
160
Figure 42. Normal distribution curve for Hybrid buildings
54
Rapid Visual Screening of Himachal Pradesh
4.5
x 10
5
RC
Brick
Stone
Rammed
Hybrid
4
No. of Buildings
3.5
3
2.5
2
1.5
1
0.5
0
40
60
80
100
120
140
RVS Score
160
180
200
Figure 43. Normal distribution curve typology wise
7. Conclusions
An attempt has been made to do rapid visual screening of five varieties of
buildings in Himachal Pradesh state. RVS score has calculated for 9099 buildings and
plotted normal distribution curves for each typology of building to understand the
distribution of buildings in HP state. From the study, it is clearly shown that Kangra
district have more buildings in all five different typologies.
Results of the performance scores reveal that around 17% (1541 out of 9099) of
buildings are reinforced concrete, 48% (4363 out of 9099) of buildings are brick
masonry, 15% (1341 out of 9099) of buildings are stone masonry, 5% (518 out of 9099) of
buildings are rammed earth and 15% (1318 out of 9099) of buildings are hybrid in the
whole state of Himachal Pradesh. However, there are some low RVS score buildings
which are potentially vulnerable to future earthquakes. Also it is suggested that
preliminary analysis needs to be performed on 47 buildings and detailed analysis for 15
buildings for calibrating RVS scores. Finally all the buildings will be categorized in a
few performance factors categories. After developing the fragility curves for the region,
damage due to different ground acceleration of earthquakes will be estimated.
Recommendations
55
Rapid Visual Screening of Himachal Pradesh
1. Implementation of the building code regulations for rammed earth, hybrid and
stone masonry buildings needs to be initiated in our country.
2. Structural detailing particularly near the beam-column junctions must be
improved with adequate shear reinforcement being provided.
3. Performance of the low-rise buildings constructed using locally available
materials must be improved. This factor could lead to a significant reduction of
casualties in future earthquakes.
4. Research is needed to investigate and improve the performance of the above
buildings.
Acknowledgment
The authors would like to express their gratitude to the TARU Leading Edge
Private Limited, New Delhi.
8. References
1. Jain S.K., (2005), “The Indian Earthquake Problem”, Current Science, Vol.89 (9),
pp. 1464-1466.
2. Keya Mitra (2008), “Assessing Urban Fabric Against Natural Disasters: A Case
Study of Seismic Vulnerability of Kolkata”, Ph.D Thesis, Department of
Architecture, Town and Regional Planning, Bengal Engineering and Science
University, Shibpur, India.
3. Singh P., (2005), “Population Vulnerability for Earthquake Loss Estimation using
Community Based Approach with GIS: Urban Infrastructure Management”,
Master of Science, International Institute for Geo Information Science and Earth
Observation, Netherlands.
4. FEMA 154, 1988. Rapid Visual Screening of Buildings for Potential Seismic
Hazards - A Handbook, Federal Emergency Management Agency, Washington
D.C.
5. FEMA 154/July, 1988. ATC-21, Rapid visual screening of buildings for potential
seismic hazards: A handbook, Applied Technology Council, CA.
6. FEMA 310, 1998. Handbook for the Seismic Evaluation of Buildings -A
Prestandard, Federal Emergency Management Agency, Washington D.C.
56
Rapid Visual Screening of Himachal Pradesh
7. Srikanth Terala and Pradeep Kumar Ramancharla, (2010), “Rapid Visual Survey
of Existing Buildings in Gandhidham and Adipur Cities, Kachchh, Gujarat”,
Proc. of International Symposium on the 2001 Bhuj Earthquake and Advances in
Earthsciences and Engineering, Gujarat, India.
57