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Vernacular masonry construction in Nepal: History, dynamics, vulnerability,
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In: Masonry
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© 2018 Nova Science Publishers, Inc.
Chapter 6
VERNACULAR MASONRY CONSTRUCTION
IN NEPAL: HISTORY, DYNAMICS,
VULNERABILITY, AND SUSTAINABILITY
Dipendra Gautam1,*, Hemchandra Chaulagain2,
Rajesh Rupakhety3, Rabindra Adhikari4,
Pramod Neupane5 and Hugo Rodrigues6
1
Structural and Geotechnical Dynamics Laboratory,
StreGa, DiBT, University of Molise, Campobasso, Italy
2
School of Engineering, Pokhara University, Kaski, Nepal
3
Earthquake Engineering Research Center,
University of Iceland, Selfoss, Iceland
4
Department of Civil Engineering,
Cosmos College of Management and Technology, Lalitpur, Nepal
5
Infrastructure Unit, WWF Nepal, Kathmandu
6
RISCO, School of Technology and Management,
Polytechnic Institute of Leiria, Leiria, Portugal
*
Corresponding Author Email: dipendra.gautam@unimol.it.
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D. Gautam, H. Chaulagain, R. Rupakhety et al.
ABSTRACT
Historical records depict the existence of vernacular masonry
constructions since the Vaidic period in Nepal. As described in the books,
for example, the Mahabharata, Bhagavad Gita, and others written some
5,000 years ago, different types of masonry constructions were used in
ancient times. Since the Vaidic age, gradual changes in masonry
construction, assumedly after major natural disasters, should have
occurred to reach the present day vernacular masonry forms. This chapter
outlines historical development of vernacular masonry buildings in
Nepal. This development is timelined in reference to the dynasties that
ruled Nepal. The timeline of different construction systems is presented.
Seismic vulnerability of existing vernacular masonry buildings in Nepal
is assessed and heuristic fragility functions are presented. Discussions in
terms of sustainability of these constructions and prospects of
technological advancements for vulnerability reduction are also
presented.
Keywords: vernacular construction; seismic vulnerability; fragility
function; sustainability; Nepal
INTRODUCTION
The history of masonry construction in Nepal dates back to at least
5,000 years ago. The books from the early age of eastern philosophy
authored more than 5,000 years ago present accounts of construction
practices of common dwellings, royal palaces, and temples. As civilization
developed on the lap of Himalaya, diversities in construction practices
emerged per the availability of local resources and materials.
Understanding historical construction and dynamics is crucial to preserve
traditional construction systems. This chapter describe historical
construction system and dynamics of vernacular masonry buildings in
Nepal and presents their vulnerability and sustainability level. Methods
used to derive heuristic fragility functions and sustainability assessment are
also described.
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149
HISTORY AND TIMELINE OF VERNACULAR
MASONRY CONSTRUCTION IN NEPAL
As noted earlier, documented history of building construction in Nepal
dates back to at least 5000 years. A sequential building construction
scenario could be formulated considering the history vis-à-vis historical
descriptions of building forms. A generic timeline of vernacular masonry
construction technology is formulated as shown in Figure 1.
Figure 1. Timeline of construction practices in Nepal.
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D. Gautam, H. Chaulagain, R. Rupakhety et al.
Vaidic Age
Nepal is one of the oldest nations of the world. Many places in
contemporary Nepal are mentioned in historical accounts as important
locations in the development of eastern philosophy. As mentioned in
various philosophical accounts, people used to reside primarily in small
huts. As the agricultural and herder societies were dominant around 5000
years ago, small settlements primarily comprising wattle and daub,
masonry buildings, and stone masonry construction could have been
prevalent. As there is no direct evidence of such constructions, historical
accounts are considered as documented evidence.
Cow Herders’ Age (Gopal Vansha Period)
Concrete documentation on settlement of cow herder settlements in
Nepal is lacking in the contemporary literature. Cow herders are believed
to have ruled Nepal for about 700 years -- the famous was of Mahabharata
took place during this period. As described in Mahabharata, the dwellings
in that period was dominated by small adobe huts. Royal residences at this
period have been described as masonry buildings. In the plains of Nepal,
due to lack of stones, adobe together with wattle and daub constructions
can expected to have been prevalent. However, in the middle to high
mountains, stone masonry buildings, either dry stacked stones or mud
mortar, could have been the dominant building types in this age.
The Buddha and Buffalo Herders’ Age
(Mahishpal Vansha/Aahir Period)
The buffalo herders ruled for only around 100 years their settlements
in Nepal is not well documented. However, at the same period, the Buddha
was born in the southern plain of Nepal, Lumbini. The remains of the
Buddha’s birthplace note the first documented and preserved construction
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practices in the plains of Nepal around 2500 years ago. As shown in
Figure 2, the oldest construction system depicts a massive brick masonry
wall in mud mortar. The figure further depicts that stretcher bonding was
typical during that period. Irregularly sized bricks thinner than present day
bricks can be observed in the masonry wall. Due to lack of connection
between the wythes of the masonry walls, the structural system should
mostly be understood as stacked bricks in mud mortar. Furthermore, there
is no connection between the orthogonal walls, nor such connections with
partition walls are visible.
Figure 2. The oldest masonry construction in Nepal during the Buddha period (>2550
years ago) [Image credit: Chuda Raj Dhakal].
Kirat Age
Kirats ruled Nepal for several hundred years, however, details
regarding the building forms are not well documented. Kirats usually
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resided in the middle and high mountains of Nepal, thus, their construction
could have been dominated by stone masonry (dry or mud mortar).
Lichchhavi Age
Lichhavi age is believed to be the Stone Age in Nepal as noted by
stone masonry constructions, although brick masonry and adobe
constructions were dominant in different parts of the country. Lichchhavi
age is considered as a golden age in Nepal’s history. Trade, art and culture,
painting, architecture and sculpture flourished in this era. Several landmark
constructions like the world heritage site Changunarayan were built during
this age. Regarding residential construction, the southern plains and
Kathmandu valley is thought to have predominantly adobe constructions.
On the contrary, vernacular stone masonry buildings could have been
dominant in the mountains.
Malla Age
During the Malla age, numerous inventions in terms of housing were
developed in Nepal. Mallas were good craftsmen, thus, they created a
unique architecture in Kathmandu valley and neighbouring areas. The
present-day Kathmandu valley architecture (Newari architecture) inherits
the Malla age features. Composite structures (brick masonry and wooden
members) was dominant during this age. The landmark civilization of
Kathmandu valley and neighbouring towns developed a dynamic
architectural form, i.e., Newari architecture. In early Malla age, at 1255, a
devastating earthquake of modified Mercalli intensity (MMI) ~X had
struck Kathmandu valley. It killed one-third of the population of the valley,
and most of the adobe buildings collapsed during that earthquake. This and
other earthquakes to follow are expected to have changed structural forms
and construction methods. Details regarding the structural damage due to
1255 and subsequent earthquakes can be found in Gautam and Chaulagain
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(2016) and Chaulagain et al. (2018). Meanwhile, changing context of
housing construction is depicted well in the description published by (Rana
1935). A typical Malla age building is shown in Figure 3.
Figure 3. Vernacular Newari building in Kathmandu valley.
Shah Age
After the unification of Nepal in 1768 by the Gorkhali king Prithvi
Narayan Shah, Shah Dynasty ruled Nepal for 238 years. During this age,
most of the architectural forms were replicated from Malla age in the urban
neighbourhoods; whereas, the rural settlements continued to use the
traditional forms for most of the Shah age. During the same age, reinforced
concrete buildings were introduced in Nepal in the late 1960s. After the
1988 Earthquake in eastern Nepal, the then His Majesty’s Government of
Nepal drafted a building code for Nepal. After the restoration of
democracy in 1990, urbanization started growing rapidly; which took
exponential pace after the 2000s.
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Rana Age
Rana dynasty ruled Nepal between 1846 and 1951. During Rana age, a
unique massive masonry construction system, also known as Greco-Roman
construction system, was introduced in Nepal for residential and
administrative buildings. The Greco-Roman construction system is a
massive wall multi-storied construction system with large plinth area and
large columns which are like the ones found in ancient Greek and Roman
architecture. Most of such buildings exist in Nepal in Kathmandu valley
today. The use of mortar and its quality in these constructions is
praiseworthy. However, their massive structure was not compliant with the
seismicity of the region. They suffered severe damage during the 2015
Gorkha earthquake (Gautam 2017). Figure 4 shows a Rana age GrecoRoman building located in Kathmandu Durbar Square.
Figure 4. Greco-Roman building located in Kathmandu Durbar Square.
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Modern Nepal
After Prithvi Narayan Shah unified Nepal in the 18th century, the age is
considered as the modern age in Nepal’s history. Both Shah and Rana
dynasties have ruled modern Nepal. Most of the landmark constructions
that can be seen nowadays were concentrated in urban areas and suburbs
only. At the meantime, rural settlements in Nepal had developed unique
buildings forms and settlements patterns. Figure 5 depicts a dense row
settlement in western Nepal (Ghale gaun). In modern Nepal, due to
economic and climatic reasons, diverse construction systems emerged in
different parts of rural Nepal. However, cultural barriers and beliefs have
played some role in adoption of modern construction styles. For instance,
the Tharu community in southern plains of Nepal is not comfortable with
multi-storied dwellings. This has resulted in some Tharu settlements in
Nepal to be homogenously constructed. Due to climatic variation,
availability of construction materials, and cultural beliefs, hundreds, if not
thousands, of structural forms can be identified in Nepal.
Figure 5. Row housing settlement in western Nepal [Image credit: Prakriti Sharma].
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SEISMIC VULNERABILITY OF VERNACULAR
BUILDINGS IN NEPAL
Seismic vulnerability of vernacular buildings in Nepal is seldom
discussed in Nepal as most of the studies focus on modern reinforced
concrete buildings. Only few studies (e.g., Gautam 2018) have attempted
to describe seismic vulnerability of some vernacular constructions.
However, all past studies have considered one or two building forms only,
hence, a thorough study on seismic vulnerability of many existing
vernacular building forms in Nepal is important. Previous studies by
Chaulagain et al. (2016) and (Gautam 2018) have presented seismic
fragility functions for some masonry buildings. However, both of the
studies have considered diverse building forms as a class. To this end, this
study considers 13 different vernacular building types in Nepal that could
represent almost 70% of existing masonry construction in Nepal. As noted
by several researchers in the past, owing to uncertainties and lack of
damage database, heuristic fragility formulation framework is used in this
work. A summary of the framework is presented in Figure 6.
In total 13 different vernacular masonry building classes were
identified and their performance levels performance levels were defined
following the FEMA-273 guidelines (Federal Emergency Management
Agency 1997). Thereafter, an expert-opinion form was developed and
circulated to identify peers. Judgments were requested for the lower bound
and median peak ground accelerations (PGA) corresponding to each
performance level for all building classes. Based on the methodology
devised by Porter et al. (2007a), the combined lower bound PGA (λ) can be
calculated using Eq. (1).
∑𝑛 𝑤 𝛼 𝜆
𝑖 𝑖
𝜆 = ∑𝑖=1
𝑛
𝑤𝛼
𝑖=1
(1)
𝑖
Similarly, the combined median PGA (Ɵ) for each performance level
was estimated by using Eq. (2).
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∑𝑛 𝑤 𝛼 𝜃
𝑖 𝑖
𝜃 = ∑𝑖=1
𝑛
𝑤𝛼
𝑖=1
157
(2)
𝑖
Figure 6. Methodology to derive heuristic fragility functions.
In Eqs. (1) and (2), wi is the weight assigned to the lowerbound PGA
value (𝜆𝑖 ) judged by expert i, 𝛼 = 1.5, n is the total number of expert
judgements available, and 𝜃𝑖 is the median PGA value judged by expert i.
Once the combined lower bound and median PGAs are estimated, the
logarithmic standard deviation (γ) can be estimated as:
𝜃
ln( )
𝜆
𝛾 = 1.28
(3)
In the case of heuristic fragility functions, it is crucial to note that the
logarithmic standard deviation should not be less than 0.4 (Porter et al.
2007b), thus the median value should be adjusted as follows:
𝜃𝑖 = 1.67 𝜆𝑖 [𝑖𝑓 𝛾𝑖 < 0.4]
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(4)
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Table 1. Estimated Gaussian parameters for different types
of vernacular buildings
Building type
Performance level
Vernacular Khas buildings of the middle
mountains (Figure 7a)
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
Vernacular middle mountain stone masonry
building (Figure 7b)
Rounded vernacular stone masonry building
(Ghumaune ghar) (Figure 7c)
Elliptical stone masonry buildings (Figure 7d)
Vernacular Newari building (Newari chhen)
(Figure 7e)
Gaussian
parameter
ɵ
γ
0.07
0.61
0.11
0.56
0.15
0.41
0.19
0.40
0.25
0.40
0.30
0.40
0.35
0.40
0.06
0.51
0.09
0.40
0.14
0.40
0.19
0.40
0.23
0.40
0.30
0.40
0.39
0.40
0.09
0.44
0.14
0.42
0.20
0.40
0.26
0.40
0.35
0.40
0.43
0.40
0.50
0.40
0.09
0.62
0.13
0.46
0.18
0.45
0.22
0.43
0.27
0.40
0.33
0.40
0.40
0.40
0.06
0.50
0.10
0.47
0.14
0.40
0.18
0.40
0.22
0.40
0.25
0.40
0.30
0.40
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Vernacular Masonry Construction in Nepal
Building type
Performance level
Mixed vernacular building (mud blocks and stone
masonry)
(Figure 7f)
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
Rubble stone masonry with bands (Figure 8a)
Vernacular Bhawar building (Stone masonry with
timber posts and thatched roof) (Figure 8b)
Himalayan vernacular dry-stone masonry building
(Figure 8c)
High Himalayan stone masonry building with
wooden bands
(Figure 8d)
Tundra vernacular building (Figure 9a)
Gaussian
parameter
ɵ
γ
0.05
0.43
0.08
0.40
0.09
0.40
0.16
0.40
0.20
0.40
0.23
0.40
0.27
0.40
0.07
0.64
0.12
0.69
0.15
0.47
0.18
0.40
0.22
0.43
0.26
0.40
0.29
0.40
0.06
0.45
0.10
0.46
0.15
0.40
0.20
0.40
0.23
0.40
0.28
0.40
0.33
0.20
0.05
0.45
0.08
0.44
0.12
0.40
0.16
0.40
0.20
0.40
0.25
0.40
0.33
0.40
0.09
0.66
0.14
0.51
0.18
0.40
0.25
0.40
0.31
0.40
0.35
0.40
0.40
0.40
0.08
0.40
0.13
0.44
0.18
0.40
0.24
0.40
0.33
0.40
0.38
0.40
0.43
0.40
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Table 1. (Continued)
Building type
Performance level
Indo-Gangetic vernacular masonry building
(Figure 9b)
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
Vernacular mixed building (Figure 9c)
Gaussian
parameter
ɵ
γ
0.07
0.55
0.10
0.44
0.16
0.40
0.21
0.40
0.27
0.40
0.32
0.40
0.39
0.40
0.08
0.45
0.13
0.42
0.18
0.40
0.23
0.40
0.31
0.40
0.37
0.40
0.45
0.40
Table 2. Revised Gaussian parameters for the High Himalayan stone
masonry buildings with wooden bands
Building type
Performance level
High Himalayan stone masonry building with
wooden bands [Figure 8a]
No damage
Immediate occupancy
Damage control
Life safety
Limited safety
Collapse prevention
Collapse
Gaussian
parameter
ɵ
γ
0.05
0.64
0.09
0.69
0.15
0.47
0.20
0.40
0.24
0.43
0.29
0.40
0.33
0.40
It is further crucial to note that the fragility curves for each of the
performance levels are not expected to cross each other. In the case of such
crossing, adjustment of combined median PGA (Ɵ) is expected. The
adjustment could be done in two steps: the first one is the estimation of
average lognormal standard deviation (𝛾 ′ ) and the second step is the
revision of the median PGA (𝜃 ′ ). Eqs. (5) and (6) depict these steps.
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Figure 7. a) Vernacular Khas building of middle mountains, b) Vernacular middle
mountain stone masonry building, c) Vernacular Newari building, d) Rounded
vernacular stone masonry building, e) Elliptical stone masonry buildings, f) Mixed
vernacular building (mud blocks and stone masonry) [Image credit: Yogi Kayastha].
Figure 8. a) Rubble stone masonry with bands, b) Vernacular Bhawar building (Stone
masonry with timber posts and thatched roof), c) Himalayan vernacular dry-stone
masonry building, d) High Himalayan stone masonry building with wooden bands
[Image credits: Yogi Kayastha].
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Figure 9. a) Tundra vernacular building [Image credit: Yogi Kayastha], b) IndoGangetic vernacular masonry building [Image credit: Yogi Kayastha], c) Vernacular
mixed building.
1
𝛾 ′ = 𝑛 ∑𝑛𝑖=1 𝛾𝑖
(5)
𝜃𝑖′ = 𝐸𝑋𝑃(1.28(𝛾 ′ − 𝛾𝑖 ) + ln 𝜃𝑖 )
(6)
A summary of the estimated Gaussian parameters is presented in
Table 1. The fragility functions derived for the High Himalayan stone
masonry building with wooden bands (Figure 8a) intersected for some
performance levels. Thus, the Gaussian parameters were re-estimated for
all performance levels. Table 2 depicts the revised Gaussian parameters for
the High Himalayan stone masonry buildings with wooden bands.
Figure 7a shows a typical vernacular Khas masonry building in middle
mountains of Nepal. Usually, such buildings are constructed directly above
river banks. There is no sufficient record of the inception of such
construction; however, it is thought to have emerged with the Sinja valley
civilization which started in the 12th century. Khas vernacular buildings are
characterized by three storied construction with large overlooking windows
at several locations. Tiles are used as the roofing material. Such buildings
are primarily located in the central to western middle mountains of Nepal
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where people of Khas ethnicity reside. Their construction system differs
from that of the Newars (Figure 7c) in terms of height of the building,
distribution of openings, brick type, and gable window. The fragility
functions for various performance levels for the Khas vernacular building
are shown in Figure 10.
In the middle mountains of Nepal, mostly stone masonry construction
system is practiced due to abundance of field stones that can be easily
shaped with minor tools into building stones. In western Nepal, dry-stone
masonry construction is widely practiced as shown in Figures 5 and 7b.
Dry-stone masonry constructions are amongst the most vulnerable
buildings of Nepal due to lack of binding material between the masonry
units. However, it should be noted that dry-stone masonry construction
system is limited to one- to two-stories only. The fragility functions for
dry-stone masonry buildings in Nepal are shown in Figure 11.
Figure 10. Fragility curves for the vernacular Khas building of middle mountains.
The Newari vernacular construction system started in Nepal when
Newars entered Nepal from the southern plains and settled in Kathmandu
valley and neighbouring areas. Newari vernacular buildings are usually
four-storied, i.e., Chheli (ground story), Matan (first story), Chota (second
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story), and Buigal (top story) as shown in Figure 7c. Newari vernacular
buildings have massive structural masonry wall system unlike the Khas
vernacular buildings.
Figure 11. Fragility curves for vernacular middle mountain stone masonry building.
Figure 12. Fragility curves for vernacular Newari building.
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Figure 13. Fragility curves for rounded vernacular stone masonry building.
Figure 14. Fragility curves for elliptical stone masonry buildings.
The wall thickness is usually >40 cm. Smaller and limited number of
openings can be found in all traditional Newari settlements. The uppermost
floor heights are smaller than the lower ones also have a lower height when
compared to the lower ones. The fragility functions for Newari buildings is
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depicted in Figure 12. Figure 7d shows a Ghumaune ghar (rounded stone
masonry building) that can be found in western Nepal. Number of such
buildings is diminishing due to complication in construction technology
and lack of knowledge transfer. Thatched roof is provided in such
buildings and a central wooden post supports the roof. Historical records
show that the Rounded buildings survived significant earthquakes and
remained occupiable for more than 100 years (Chaulagain et al. 2018).
Fragility functions for the Rounded stone masonry buildings of western
Nepal are shown in Figure 13.
Elliptical stone masonry buildings (Figure 7e) are also found in
western Nepal. They are relatively fewer compared to the other building
forms. Elliptical vernacular buildings are usually not plastered, and slates
are used as roofing system. Such buildings are sometimes two storied; in
which case the upper story is made from timber. Unlike Rounded stone
masonry buildings, elliptical buildings have wooden struts to carry loads
from their overhanging parts. Fragility functions for Elliptical stone
masonry buildings are shown in Figure 14.
In the middle mountains of Nepal, stone and mud blocks are used for
construction (Figure 7f) when stones are not abundant, and quarrying is
tedious. The upper stories are usually provided with mud-blocks. Due to
mixed nature of the masonry units, such buildings are highly vulnerable to
seismic shaking. The durability of such buildings is not satisfactory. Such
buildings usually have a useful life of around 30 years. Fragility functions
for the mixed vernacular buildings are shown in Figure 15.
The higher Himalayan buildings in the Middle Western part of Nepal
are characterized by two-storied stone masonry constructions with wooden
bands (Figure 8a). These buildings are considerably lower than other types
and are suitable for the cold climate in the higher Himalaya. Upper story of
such buildings can sometimes have wattle and daub system as well.
Fragility functions for various performance levels for the higher
Himalayan stone masonry buildings with wooden bands are depicted in
Figure 16.
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Figure 15. Fragility curves for mud blocks with stone masonry.
Figure 16. Fragility functions for rubble stone masonry with bands.
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Figure 17. Fragility functions for vernacular Bhawar building (Stone masonry with
wooden posts and thatched roof).
Figure 18. Fragility curves for Himalayan vernacular dry-stone masonry building.
The vernacular Bhawar buildings (Figure 8b) are dominant structural
forms of Bhawar region, the region in between the southern Indo-Gangetic
plains and the Siwaliks. Due to the availability of timber in the vicinity,
composite construction system is usually practiced in Bhawar region. For
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stability and safety purpose, people construct buildings with stone masonry
and timber and thatched roofing system is common. Fragility functions for
such buildings are shown in Figure 17.
The Himalayan vernacular dry-stone masonry (Figure 8c) can be found
in the high Himalayan regions of Nepal. Such buildings are single storied
stacked stone masonry constructions without any connection between the
orthogonal walls. The roofing system consists of a layer of clay covered by
bushes or shrubs to avoid the direct impact of sun and snow. The fragility
functions such buildings are shown in Figure 18.
Figure 19. Fragility functions for High Himalayan stone masonry building with
wooden bands.
In the middle to high mountains of Nepal, multi-storied stone masonry
buildings are common in Nepal (Figure 8d). These vernacular buildings are
related to the Sinja Valley Civilization. Multiple wooden bands throughout
the perimeter could be found in all the buildings of some settlements in the
mid-western Himalayan region. In some buildings, structural walls are
setback from one another. However, most of the buildings are uniform,
thick-walled constructions with five or more wooden bands at various
levels. Figure 19 presents the fragility functions for such buildings.
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Figure 20. Fragility functions for Tundra vernacular building.
Figure 21. Fragility functions for Indo-Gangetic vernacular masonry building.
The most unique vernacular masonry building in Nepal is the Tundra
vernacular building (Figure 9a). Tundra buildings are constructed in layers
of locally available clay. Tundra buildings are constructed in the
Himalayan region where settlements are sparse. Due to extreme weather,
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low height single-storied buildings are common. The clay layers are
rammed at several layers and finally stabilized to from a thick wall. Thick
wall and small openings are crucial for heat insulation. Due to low
precipitation rate, flat roofs are provided in Tundra buildings. Fragility
functions for the Tundra masonry buildings are depicted in Figure 20.
In the temperate regions of Nepal, proper building construction is
crucial for coping heat waves during the summer and cold waves during
the winter. Thus, the vernacular construction practice in the indigenous
settlements adopts single storied thick-walled masonry buildings with tiles
as roofing material. Figure 9b shows vernacular Tharu building in western
Nepal. Such buildings have walls made up of sun-burnt clay bricks.
Fragility function for such buildings is shown in Figure 21.
Figure 22. Fragility functions for vernacular mixed building.
In the Siwaliks of eastern Nepal, vernacular mixed construction
practice (Figure 9c) can be found to some extent. Most of such buildings
are two-storied; the ground story is constructed from locally manufactured
masonry units (clay blocks) and the first story is made from timber.
Roofing is made of tiles. Due to the availability of wood in the vicinity,
timber is used in the first story. To protect against frequent annual
torrential precipitation and inundation, ground story is constructed from
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D. Gautam, H. Chaulagain, R. Rupakhety et al.
clay blocks. To shelter against heat during summer, roof tiles are used. The
fragility functions for the vernacular mixed masonry building are shown in
Figure 22.
As shown in the figures above, most of the masonry buildings in Nepal
have poor seismic resistance even at minor to moderate shaking. However,
some of the structural forms have shown remarkable performance levels
during moderate to strong earthquakes. In general, most of the vernacular
buildings in Nepal should be understood as highly vulnerable in light of
impending hazard.
SUSTAINABILITY OF VERNACULAR MASONRY
CONSTRUCTIONS IN NEPAL: PAST, PRESENT, AND FUTURE
Vernacular construction systems in Nepal use only local resources and
technology. The vernacular construction technology is polished continually
so that modified forms of construction have evolved, especially after major
natural disasters. To date, to the best of our knowledge, sustainability of
vernacular constructions in Nepal has not been assessed. To fulfil this gap,
this chapter assesses the sustainability of the considered building classes
based on the parameters that are modified and localized to Nepal from the
American Society of Civil Engineers guidelines (American Society of
Civil Engineers 2010). Seven parameters are considered for sustainability
analysis. Three levels of sustainability levels, i.e., high, medium, and low,
are considered in this study as qualitative measures. High level indicates
excellent sustainability; medium level indicates average sustainability, and
low denotes essentially unsustainable constructions. Table 3 outlines the
sustainability analysis of 13 vernacular buildings in Nepal.
As shown in Table 3, all vernacular building forms considered depict
medium to high level of sustainability; however, sustainability used in this
chapter is qualitative and quantification of sustainability parameters for
Nepali buildings is still underway. However, it should be noted that
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sustainability, being a vital component of present-day structural
engineering, is obviously notable in Nepali vernacular masonry buildings.
Table 3. Sustainability of vernacular buildings in Nepal
Building
type
(Figure)
Figure 7a
Figure 7b
Figure 7c
Figure 7d
Figure 7e
Figure 7f
Figure 8a
Figure 8b
Figure 8c
Figure 8d
Figure 9a
Figure 9b
Figure 9c
Sustainability parameters
Recycling Local
Durability Reusability Adaptability Environment, Overall
resources and
toxicity, and sustainability
maintenance
structural
level
materials
Low
High
Medium
Low
Low
High
Medium
High
High
Medium
High
High
High
High
Low
High
Low
Low
Medium
High
Low
High
High
High
High
High
High
High
High
High
High
High
High
High
High
Medium Medium Low
Medium
Medium
Medium
Medium
Medium High
Low
Medium
High
High
Medium
High
High
Medium
Medium
High
High
Medium
Medium High
Low
Medium
High
High
Medium
Medium High
Low
Medium
High
High
Medium
High
High
Medium
High
High
High
High
Low
Medium Low
Medium
High
High
Medium
Medium High
Medium
High
High
High
High
CONCLUSION
Considering 13 vernacular buildings in Nepal, we present
sustainability and vulnerability of representative masonry constructions in
Nepal. Apart from this, history and dynamics of vernacular masonry
construction from Vaidic to the modern age in Nepal is outlined. A
tentative timeline of construction practices is also presented, and this could
be important in understanding and improvising the construction systems
for resilience against multi-hazards, while at the same time respecting
cultural beliefs and local needs. The sum of results highlights that Nepali
vernacular buildings have appreciable sustainability; however, seismic
performance is not satisfactory. This raises an important, yet unanswered
question in risk mitigation of vernacular constructions. The usual and
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D. Gautam, H. Chaulagain, R. Rupakhety et al.
straightforward option is to use advanced construction materials such as
reinforced concrete. While this option, if implemented correctly, can help
reduce seismic vulnerability, it is, to a large extent economically
restrictive, and more importantly, not as sustainable as the vernacular
systems. It is, however, not our intention to argue for vernacular buildings
against modern construction systems and materials. Long term
sustainability and economic feasibility, however, requires studies and
research on low cost seismic strengthening of vernacular buildings. This is
a field of research that has huge and widespread potential impact on people
living under seismic risk in developing countries, but unfortunately, has
not received due attention in research in more advanced countries.
ACKNOWLEDGMENTS
Authors would like to appreciate the support provided by Digicon
Consult, Lalitpur and Cosmos College of Management and Technology.
Yogi Kayastha, Prakriti Sharma, Chuda Raj Dhakal, and many other
people have contributed when collecting the information; authors express
their sincere gratitude to all. The local people who provided access to
assess the buildings are also acknowledged for their help. Authors are
grateful to the experts for their valuable time to provide the expert
judgement.
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