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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.

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Report # 71 : Reinforced concrete frame structure with diagonal bracing and brick infill walls

by Maria D. Bostenaru, Ilie Sandu

This is a post-World War II variant of the well-known Romanian ‘inter-bellum’ building. This urban housing construction was practiced in Romania over a rather short period of time after World War II until nationalization in 1947. Buildings of this type are still in use, mainly as apartment buildings. They are typically 7 to 11 stories high and the main load-bearing structure consists of a reinforced concrete space frame with reinforced concrete diagonal bracings. The floor structure consists of RC solid slabs and beams cast-in-place. The frames are infilled with brick masonry walls (typical wall thickness 140 mm or 280 mm). These buildings were designed according to the temporary guidelines issued in 1941 by the Ministry of Public Works (MLP) and based on German recommendations. This region is well known as a seismically prone area, with the epicenter of damaging earthquakes close to Vrancea. Earthquakes of Richter magnitude over 7.0 occur once in 30 years. Bucharest, the capital, is located around 150 km south of the epicenter and lies in the main direction of the propagation of seismic waves. The Bucharest area is located on the banks of the Dâmbovita and Colentina rivers, on non-homogeneous alluvial soil deposits. During the earthquake of 4 March 1977 (Richter magnitude 7.2), over 30 buildings collapsed in Bucharest, killing 1,424 people. It should be noted that although buildings of this construction type experienced severe damage (mainly cracking in the columns and the brick masonry infill walls) collapse was not reported. After the 1977 Vrancea earthquake, the damaged buildings were repaired and strengthened. One of the buildings described in this contribution was retrofitted by strengthening the existing columns with new reinforced concrete jackets and by replacing the existing brick masonry infill walls with new lightweight concrete block walls. The diagonal bracings were removed as a part of the retrofit. Another example shows a triangular-shaped building with the original bracing preserved during the retrofit.

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Report # 70 : Solid brick masonry house with composite hollow clay tile and concrete joist roof slabs

by Virginia I. Rodriguez, Maria I. Yacante, Sergio Reiloba

This housing type is found in the urban areas of San Juan province. It is a one-story, detached or semi-detached building, mainly used as a single-family house. The strength of this construction type is due to its solid brick walls confined with concrete tie-beams and tie-columns. The roof slabs are of composite concrete and masonry hollow clay tile construction, which form a diaphragm tied to the walls. The deficiency of this type of construction is found in the slabs which suffer serious deterioration due to the effects of humidity. This housing type is expected to have good seismic behavior.

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Report # 69 : Confined masonry building with concrete floor slabs

by Nikola Muravljov, Radovan Dimitrijevic

This type of construction has been used for single-family and medium-rise residential buildings throughout urban and rural Yugoslavia during the past 30 years. The structure consists of load-bearing masonry (brick, stone, concrete block) walls confined with reinforced-concrete posts and tie-beams. The walls are typically made of hollow clay tiles. Floor slabs are composed of prefabricated joists infilled with brick elements and topped with a reinforced-concrete slab in-situ.

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Report # 68 : Precast, prestressed concrete frame structure with concrete shear walls

by Radovan Dimitrijevic

This housing type is a prefabricated frame structure, consisting of precast concrete columns and other structural elements, e.g., waffle floor slabs, edge girders, stairs, and wall panels. The frame structure carries the gravity load, while shear walls are the main lateral load-resisting elements. The main feature of this technology is that the key structural elements are joined together by prestressing in two orthogonal horizontal directions. The technology has been used in Yugoslavia during the last 40 years under the proprietary name, IMS Building System, and it can be found in all major Yugoslav cities, including Belgrade, Novi Sad, Nis, etc., and also in other countries, such as Cuba, the Philippines, and Egypt. To date, around 400,000 housing units (approximately 2.5 million m² of the built area) have been constructed using this technology. Design applications include both residential housing and public buildings (e.g., hospitals). Seismic performance of the main IMS structural elements has undergone extensive experimental laboratory tests, and has also been tested in a few major earthquakes. Several buildings of this type sustained the effects of the 1968 Banja Luka earthquake without any damage.

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Report # 67 : Popular, non-engineered urban housing on flat terrain

by Argimiro C. Gandica, Francisco L. Almansa

This is an urban housing construction type found in the Andean states of Venezuela. In some cities, e.g., Merida, this construction accounts for 40% of the total building stock. Typical buildings of this type are two to three stories high. Typically, there are two or three bays in the longitudinal direction (spaced at 3 to 4 m) and four or five bays in the transverse direction (4 to 5 m apart). The main load-bearing system consists of reinforced concrete frame (columns and beams) with hollow clay tile, and masonry-infill walls. The roof structure consists of lightweight roofing (zinc and/or acclimatized galvanized sheets) supported by I-shaped steel beams. The building’s roof level is used as a terrace with a one-meter-high masonry parapet, which serves as a guardrail on the slab perimeter. This is a non-engineered construction, i.e., these buildings are constructed by the owners. Because of the lack of adequate detailing in the longitudinal and transverse steel reinforcement bars, beam-column connections are inadequate and do not provide the continuity required for adequate seismic performance.

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Report # 66 : Precast reinforced concrete frame panel system of seria IIS-04

by Shamil Khakimov, Bakhtiar Nurtaev

This housing type is used in the construction of residential and public buildings in many cities throughout Uzbekistan (including the capital city Tashkent) that are located in zones with intensities between 7-9. Residential buildings of this type are generally 9 to 12 stories high, whereas public buildings of the same construction are 1 to 4 stories high. All seismic load-resisting (and also nonstructural) components, e.g., foundations, columns, girders, slabs, staircases, wall panels, etc., are manufactured in specialized plants. The materials are subsequently transported to the building site. The positive features of this construction type are (1) the ability to manufacture all building materials in an industrialized setting, and (2) the gain in efficiency inasmuch as the same building components may be used both for residential and public buildings. The key drawback is that the welded joints cause seismic vulnerability when the building is located in zones of extremely high seismic loads. These joints have shown extremely brittle behavior during earthquakes. Earthquake damage is mainly concentrated in the column joints, or in the column-to-girder joints. In some cases non-bearing walls and exterior wall panels have collapsed.

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Report # 65 : Wood frame single family house

by Christopher Arnold

Wood frame construction is typical for single family houses throughout the USA. Historically, in the East, Midwestern and South, brick masonry and stone were used for house construction, but this began to be superseded by wood frame around the turn of the 19th century. In the earthquake-prone western part of the US, wood frame has been dominant over stone and brick. The development of present-day wood frame construction began with the appearance of standardized sawn lumber and cheap machine-made nails. By 1840, the typical wood frame house was built of milled lumber in standard sizes. The standardized wood frame structure is now augmented by a wide range of compatible standardized components such as doors, windows, electrical and plumbing fixtures, and the like, that are designed to be easily installed in the wood structure. Because wood frame walls are hollow, alternative levels of insulation can be installed, enabling accommodation of any climatic conditions and easy installation of plumbing and electrical services within walls, in the open spaces above the ceilings, within the floor structure, and in the space between the first (ground) floor and the ground below. Because of their light weight (compared to brick or stone), their relatively large number of walls, and the use of a multiplicity of nails for connections, wood frame houses have traditionally performed well in earthquakes. Deaths and serious injuries are very rare in these structures. Today’s wood frame construction is highly codified and regulated, with a good standard of inspection by suburban local building departments in earthquake-prone regions. In smaller towns and rural areas quality control may be lacking.

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Report # 63 : High-rise, reinforced concrete buildings with open space at the ground floor

by Su C. Tung, George C. Yao


This is an urban housing construction. Typically, these are 12-story apartment buildings with a parking area in the basement. The first and second floor are classified as Open Space (OS) and the ground floor is used by the residents for gardening and for leisure and social gatherings. The common features in these buildings are: (1) The two lower floors were designed for the OS with a net height of approximately 7.6 meters. (2) There are many walls above the third floor in both horizontal directions but very few walls on the OS except around the elevator shaft and the staircases. If the elevator is located at the corner of the building, torsional effect may be present. (3) Architects tend to design zigzag floor plans for these buildings in order to maximize view angle and natural lighting. (4) Very few columns were designed into these buildings in order to maximize the parking area on the basement level. The primary load-resisting system is reinforced concrete moment-resisting frame on a mat foundation. The fact that the partition walls are dense at the third floor and above, creates a soft-story configuration in the lateral load-resisting system. Many buildings of this type collapsed in the 1999 Chi-Chi earthquake due to the soft-story effect caused by the OS design

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Report # 62 : Street front building with arcade at the first floor (contemporary construction)

by George C. Yao, M. S. Sheu

This building type is common in many Taiwanese cities and towns. The street-front buildings are medium-rise, reinforced concrete frames with infill brick masonry walls serving as partitions. Usually, the first floor (typically 4 m high) is used for commercial purposes while the upper stories (typically 2 to 4 stories above, floor height 3 m) are used for storage and residences. Neighboring units of similar design have been constructed together to form a corridor for pedestrians to walk in. Connected units vary in number from 6 to 10 and they may be built in a row, in an L shape, or in the U shape. There are several structural deficiencies associated with this building type: (1) the weak and soft first story can result from a large opening at the street level for commercial use; (2) a typical building layout has walls in one direction only, perpendicular to the street; as a consequence, there are few earthquake-resisting elements in the other direction; (3) extra rooftop additions increase loads. Also, building owners tend to reduce the number of columns for a wider storefront view. Many buildings of this type collapsed in the Chi-Chi earthquake of 1999

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