Report # 172 : Dry Stone Construction in Himachal Pradesh

by Ankita Sood, Aditya Rahul, Yogendra Singh, Dominik H. Lang

The addressed building type has been identified in Himachal Pradesh, a northern state in India. It is a
relatively recent construction typology, which can be seen prevalent in the areas where people have
been forced to leave their traditional construction practices due to scarcity of wood. Thus, this
construction style is nothing but the traditional housing style omitting the wooden elements, be it
Kath-Kunni style of the Kullu, Shimla or Kinnaur districts or Thathara style of Chamba district. Due
to the region’s heavy precipitation both in terms of rainfall (June to July) as well as snowfall (October
to March), rubble stones are preferred over the alternative locally available construction material, i.e.
mud. However, these buildings possess high seismic vulnerability due to low in-plane and out-ofplane
strength of their dry stone walls. This report identifies the main sources of seismic vulnerability
of dry stone buildings and also suggests a retrofitting scheme to reduce the seismic vulnerability of
such buildings.

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Report #171 : Mud Wall Construction in Spiti Valley

by Ankita Sood, Aditya Rahul, Yogendra Singh, Dominik H. Lang

This report describes a building type found in Himachal Pradesh, a northern state in India. It is
concentrated in the upper reaches of the state in the Lahaul and Spiti districts, which are located in a
cold-desert area with very hot days and chilling nights. Precipitation usually only occurs in the form
of snowfall with almost no to very little rainfall. This dryness of the local climate is reflected in the
architecture of this construction typology which consists of thick mud walls with small openings in
order to insulate the interior from the harsh outside climate. This style of construction which is
predominantly used for residential houses and temples is still being practiced though it shows high
seismic vulnerability.


Report #170: Thathara Houses in Himachal Pradesh

by  Aditya Rahul, Ankita Sood, Yogendra Singh, Dominik H. Lang    

The addressed building type has been identified in Himachal Pradesh, a northern state in India. Nowadays, this type of construction practice can be seen for houses and temples, however, earlier photographs suggest that the same style was adopted to build palaces, bridges as well as various other structures. The construction style is named ‘Thathara’ as this term is locally used for wooden planks that make the vertical load-carrying members (columns) locally known as Thola(s). Tholas (a peculiar combination of timber and stone) and wood are primarily used for the vertical and horizontal frame elements, respectively. The region where this building typology is found is characterized by cold climate and witnesses heavy rainfall during the rainy season (from June to July) as well as snowfalls in winter (from October to March). These effects have been considered well in the construction style, like e.g. small openings, a verandah to take sun but prevent from rain and snow, wooden and mud interiors which are good insulators and keep the interiors warm, sloping roofs with adequate projections as well as other features. Being located in the Himalayan region, the area has experienced numerous strong earthquakes and this construction technique has eventually evolved to resist seismic action.


Report #154: Assam-type House

by  Hemant B. Kaushik, K. S. Ravindra Babu    

Assam-type houses are commonly found in the northeastern states of India. Generally, it is a single storey house; however, two-storey houses are also found at some places. The main function or use of this construction type is multi-family housing. These are generally single dwelling units and do not have common walls with adjacent buildings. The house is made largely using wood-based materials. Performance of Assam-type houses has been extremely good in several past earthquakes in the region. Structural strengths that influence earthquake safety of the house include good configuration, light-weight materials used for walls and roofs, flexible connections between various wooden elements at different levels, etc. However, the houses are vulnerable to fire because of use of untreated wood-based materials. When built on hill slopes,unequal length of the vertical posts leads to unsymmetrical shaking that may damage the house.


Report # 146: Dhajji Dewari

by  Kubilây Hiçyılmaz, Jitendra Bothara, Maggie Stephenson    

Dhajji dewari (Persian for “patch quilt wall”) is a traditional building type found in the western Himalayas. Such houses are found in both the Pakistan and Indian Administered Kashmir. This form of construction is also referred to in the Indian Standard Codes as brick nogged timber frame construction. Dhajji most commonly (but not exclusively) consists of a braced timber frame. The spaces left between the bracing and/or frames is filled with a thin wall (single wythe) of stone or brick masonry traditionally laid into mud mortar. Completed walls are plastered in mud mortar. They are typically founded on shallow foundations made from stone masonry.

Dhajji buildings are typically 1-4 storeys tall and the roof may be a flat timber and mud roof, or a pitched roof with timber/metal sheeting. This building system is often used side-by-side or above timber laced masonry bearing-wall construction known as taq, bhater, unreinforced masonry and is also used extensively in combination with timber frame and board/plank construction or load bearing timber board construction.

The floors of these houses are made with timber beams that span between walls. Timber floor boards, which span over the floor beams, would traditionally be overlain by a layer of clay (or mud).
Dhajji buildings are typically used for housing, often of large extended families. In rural areas the lowest level may be used to shelter livestock. In urban areas they are more equivalent to town houses. With time these buildings are usually extended. This construction type was and is used extensively for commercial buildings, shops, workshops, bazaars.

Because the timber framing and/or bracing is first erected the masonry does not directly carry vertical loads. Although this construction type is not formally “engineered” and is a relatively basic construction system, well maintained ones performed reasonably well during the 8th October 2005 earthquake in both Pakistan and India.

The earthquake resistance of a dhajji building is developed in the following ways. Because of the weak mortar, the masonry infill panels quickly crack in-plane thereby absorbing energy through friction against the timber framing, and between the cracks in the fill material and the infill material and the hysteretic behaviour of the many mud layers. The timber frame and closely spaced bracing, which essentially remains elastic, prevents large cracks from propagating through the infill walls and provide robust boundary conditions for the infill material to arch against and thus resist out of plane inertial loads. Because the framing and/or bracing is often extensive and close together, particularly when rubble stone is used as the infill, it is possible for keep the masonry walls relatively thin. This helps to reduce the mass of the building and therefore the inertial forces that must be resisted during an earthquake. The “soft” behaviour of the system has the additional benefit of de-tuning the building from the energy rich content of earthquake excitation.

Good quality timber and experienced craftsmen are the vital components to ensure the proper detailing of the buildings timber components during construction, as well as resistance against premature decay. The technology to build such a house is simple. Builders have a large degree of control over the quality of the building materials they use because the materials are sourced locally from the natural environment and are not dependant on manufacturing processes. It is often the owner who is responsible for the selection and purchase of materials and therefore often he who decides on the timber quality to be used on a project. It is rare that the “Mistris” (term used in Kashmir to describe craftsmen such as carpenters and masons) have any significant say in the quality of the purchased materials.

These structures are environmental friendly and traditionally would not have incorporated any toxic products in their construction, apart from the natural fungal and insect resistant chemicals in the timber itself.


Report # 150 : Timber-reinforced Stone Masonry (Koti Banal Architecture) of Uttarakhand and Himachal Pradesh, Northern India

by Piyoosh Rautela, Girish Chandra Joshi, Yogendra Singh, Dominik Lang

Despite being located in a high seismic risk area, a region in the Himalayan states of Uttarakhand and Himachal Pradesh (Northern India) exhibits an elaborate tradition of constructing multistoried houses. In the Rajgarhi area of Uttarkashi district (Uttarakhand) a large number of intact buildings of the distinct construction type known as Koti Banal can be found. Koti Banal is the name of a village in the Yamuna Valley which represents the traditional knowledge and understanding of earthquake effects on buildings and their earthquake resistant design. Investigations suggest that the region had evolved this elaborate and magnificent earthquake-safe construction style as early as 1,000 years before present. This architectural style further demonstrates the existence of elaborate construction procedures based on principles somewhat akin to that of blockhouse construction. Many features of these buildings are considered as the basics of modern earthquake-resistant design. Generally, ornate multistoried houses with abundant use of wooden beams are characteristic of Rajgarhi area. For buildings of the Koti Banal architecture, locally available building materials such as long thick wooden logs, stones and slates were judiciously used. The height of these structures varies between 7 and 12 m above the base platform which consists of dry stones. These structures are observed to have four (Chaukhat) to five (Panchapura) stories. It is reported that especially buildings of the Koti Banal architecture withstood and performed well during many past damaging earthquakes in the region. In a report on the effects of the 1905 Kangra earthquake (M 7.8), Middlemiss (1910) already describes the well performance of these ?(..) top-heavy constructions? located along steep slopes of the Kangra-Kulu epicentral area, which differed ?entirely from the sun-dried brick-built structures of the Kangra Valley. The performance of these structures has also been corroborated by eye-witness accounts during the 1991 Uttarkashi earthquake which had a magnitude of mb 6.6 in an epicentral distance of 30 km during which many new buildings collapsed while these structures did not suffer any damage. The reasons that these buildings outlived so many centuries mainly lie in their structural configuration which clearly demonstrate that their builders already had the idea of dynamic earthquake actions, particularly out-of-plane failure of masonry walls. The buildings are further characterized by a number of advantageous design features such as regular plan shapes, the sensible use of locally available building materials, the integration of wooden beams over the total height of the building as well as small openings and the arrangement of shear walls.


Report # 147 : Traditional Naga Type House

by Amir Ali Khan

The housing type is most common throughout the Northeast India which lies in the most severe seismic zone of the country (Zone V – corresponding to MSK IX). Majority of this type of houses are used for residential purposes. Typically these houses are built with light weight locally available material like bamboo, wooden planks, thatch etc. These housing types have traditional system of bamboo/wooden posts. Bamboo posts are inserted into the ground to act as compression members and are tied with horizontal bamboo/wooden girders with the help of bamboo ropes (cane) to give a proper shape and framing action. However, there is no protection of bamboo/wooden posts against decaying/termites or any other natural cause. The performance of these houses during the past earthquakes is unknown. However, during the discussions with local people about the performance of these houses in the past major earthquakes, it was noted that the majority of houses survived.


Report # 116 : Timber Frame Brick House with Attic

by Amit Kumar, Jeewan Pundit

This type of house is used for residential purposes. The building type under study has been picked the from central part of India (Madhya Pradesh), but it is found throughout India with small or large variations. Timber is primarily used for the frame structural elements but due to an acute shortage of timber, this construction type is not practiced anymore. Various components of the building change from place to place depending on climate, socio-economic conditions, availability of material, etc. Timber frames, placed in longitudinal and traverse directions, are filled with brick masonry walls. The floor structure is made of timber planks. Most of the buildings are found to be rectangular in shape with few openings. The roofing material is usually light when it is made from galvanized iron sheets. Seismic performance of a perfectly framed building is very satisfactory. Existing old structures, however, require maintenance and strengthening (Figure-1a,1b). It has been observed that nominal cost will be incurred for introducing earthquake resistant features.


Report # 80 : Low-strength dressed stone masonry buildings

by Ravi Sinha, Vijaya R. Ambati


Construction of stone masonry buildings using easily available local materials is a common practice in both urban and rural parts of India. Stone masonry houses are used by the middle class and lower middle class people in urban areas, and by all classes in rural areas. In rural areas, these buildings are generally smaller in size and are used as single-story, single-family housing. In urban areas, these buildings are up to 4 stories high and are used for multifamily housing. This is a typical load-bearing construction, in which both gravity and lateral loads are resisted by the walls supported by strip footing. If the locally available stone is soft, dressed (shaped) stones are commonly used and can be chiselled at low- or moderate cost. Mud or lime mortar has been used in traditional constructions; however, more recently, cement mortar is being increasingly used. Because soft sandstone is readily available in the Kutch region of Gujarat in the western part of India, stone block masonry constructions are widely used for both single- and multi-story constructions. These houses are usually built by local artisans without formal training and the resulting constructions are structurally weak and incapable of resisting large seismic forces. In the Kutch region, which was affected by the 2001 Bhuj earthquake, this construction type is commonly used with a gable end timber roof truss or RCC roof slabs. Thousands of these houses collapsed in the 2001 Bhuj earthquake resulting in the deaths of large numbers of people. This construction type is inherently unsuitable for areas of moderate-to-high seismic hazard, such as the Kutch region of Gujarat.

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Report # 72 : Traditional rural house in Kutch region of India (bhonga)

by Madhusudan Choudhary, Kishor S. Jaiswal, Ravi Sinha

The Bhonga is a traditional construction type in the Kutch district of the Gujarat state in India, which has a very high earthquake risk. A Bhonga consists of a single cylindrically shaped room. The Bhonga has a conical roof supported by cylindrical walls. Bhonga construction has existed for several hundred years. This type of house is quite durable and appropriate for prevalent desert conditions. Due to its robustness against natural hazards as well as its pleasant aesthetics, this housing is also known as “Architecture without Architects.” It performed very well in the recent M7.6 Bhuj earthquake in 2001. Very few Bhongas experienced significant damage in the epicentral region, and the damage that did occur can be mainly attributed to poor quality of the construction materials or improper maintenance of the structure. It has also been observed that the failure of Bhongas in the last earthquake caused very few injuries to the occupants due to the type of collapse.