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 # 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 # 58 : Rubble-stone masonry house

by Marjana Lutman, Miha Tomazevic

Rubble-stone masonry houses are still found throughout Slovenia. This housing type with its special history represents a typical, older residential building in the northwestern part of Slovenia. After their destruction during World War I, these houses were rebuilt, mostly with the recycled stone material from demolished buildings. Many houses of this type were subsequently damaged during the last two earthquakes in Slovenia (1976 Friuli and 1998 Bovec). In order to preserve the country’s architectural heritage, about 66% of these houses were strengthened following these earthquakes.

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Report # 57 : Wood panel wall buildings (typical seria 181-115-77 cm of “Giprolesprom”)

by Mark Klyachko, Andrey Benin, Janna Bogdanova

This is a rural housing construction practice widespread in the forested areas of Russia. Buildings of this type are common in seismically prone areas of Russia (Far East, Siberia, Baikal Lake Region). The load-bearing structure is made of wood panel walls. Buildings have timber roof and fieldstone or concrete strip foundations. Typical seria 181-115-77 cm of ‘Giprolesprom’ for seismic regions is an example of this building type. Seismic resistance is relatively high, provided that the quality of materials and the construction are satisfactory.

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Report # 56 : Timber log building

by Mark Klyachko, Andrey Benin, Janna Bogdanova

This is a rural housing construction practice widespread in the forests of Russia. Buildings of this type are common for seismically prone areas of Russia (Far East, Siberia, Baikal Lake Region, North Caucasus). The load-bearing structure is made of wood. To construct the walls, timber logs are sawn horizontally in a square or circular cross section with special end joints (similar to dovetail joints). Buildings have timber roofs and fieldstone or concrete strip foundations. Typical seria 146-115-77 cm of ‘Giprolesprom’ for seismic regions is an example of this building type. Seismic performance of these buildings is good if the construction quality is adequate.

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Report # 55 : Large reinforced concrete panel buildings (Series 122, 135 and 1-464c)

by Mark Klyachko, Igor Mortchikchin, Igor Nudga

Large panel buildings represent one of the most common multifamily housing construction types (apartment buildings) in the former Soviet Union. Buildings of this type range from 4 to 9 stories high. This construction practice started in the 1960s and has been followed ever since. This contribution describes three different types (series) of large panel construction, known as seria 122, seria 135, and seria 1-464c. These three types (seria) are characterized by welded panel connections. The main vertical load-bearing elements, designed to carry both gravity and lateral loads, are precast reinforced concrete panels. Typically, buildings are of a regular plan and are characterized with only one interior load-bearing wall in the longitudinal direction and several walls in the transverse direction. Floor and roof structures are also made of precast reinforced concrete panels. Both wall and floor panels are of room dimensions, and the assembly of these structures consists of setting the panels in their final position and joining them in a box-type structure by means of welded joints. The methodology of achieving panel connections in large panel construction practice has significantly improved in the last 50 years. Seria 1-464c is among the first seria of large panel construction. Initially, panel joints in seria 1-464c were achieved by welding the steel elements projecting from the panels. Later on, welded joints were replaced with the monolithic joints. Seria 1-464c is characterized by a plan typical for large panel buildings with continuous walls and a typical span (2.7 m or 3.6 m) of cross walls (Figures 3C and 3D). Seria 122 is characterized by discontinuous façade walls in the longitudinal direction (Figure 3A). Seria 135 is characterized by a larger span of cross walls (6m) as compared to the other types (see figure 3B). Due to the large wall density, these buildings are rather rigid. Seismic resistance in this construction type is generally good, as these buildings have been exposed to several strong earthquakes in the former Soviet Union.

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Report # 54 : Large concrete block walls with reinforced concrete floors and roof (typical series: 1-306c, 1-307c, 114c)

by Mark Klyachko, Yuriy Gordeev, Freda Kolosova

This is a typical residential construction found both in urban and rural areas. It represents a construction practice followed in the former Soviet Union. Buildings of this type constitute 15 to 30% of the housing stock in earthquake-prone areas of Russia (Far East, Siberia, Baikal Lake Region, North Caucasus) and CIS states (Central Asia, Armenia, Georgia, etc.). The main load bearing system for lateral and gravity loads consists of concrete block masonry walls and concrete floor slabs. Seismic resistance is relatively good, provided that the welded block wall connections are present and are well constructed.

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Report # 53 : Small concrete block masonry walls with concrete floors and roofs

by Mark Klyachko, Yuriy Gordeev, Freda Kolosova

This is a typical residential construction found both in urban and rural areas. It represents a construction practice followed in the former Soviet Union. Buildings of this type constitute 15 to 30% of the housing stock in seismically prone areas of Russia (Far East, Siberia, Baikal Lake Region, North Caucasus) and in CIS states (Central Asia, Armenia, Georgia, etc.). The main load-bearing system for lateral and gravity loads consists of concrete block masonry walls and concrete floor slabs. Seismic resistance is relatively good, provided that the welded block wall connections are present and well constructed.

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Report # 31 : Brick masonry farmhouse with a “dead door”

by Agostino Goretti, Daniela Malvolti, Simona Papa

This is a single-family farmhouse construction, found throughout the Padania plain (Reggio Emilia Province). This housing type accounts for approximately 20% of the entire housing stock in the Reggio Emilia municipality. This building practice is no longer followed. Most of the existing buildings were built in the 19th and 20th centuries. The residential and agricultural sections of the house are separated by a central area closed at one end and hence called a “dead door.” The residential section usually has two floors (typical story height 2.5 – 3.0 m) and a sloping roof. The agricultural portion, usually larger than the residential section, also has two floor levels. The first-floor height is on the order of 2.5 – 3.0 m whereas the second-story floor height ranges from 5.0 – 9.0 m. As a result, the roof in the agricultural section of the building is at a higher level than that of the residential. The first floor is used as a cow shed and the second as a hayloft. The load-bearing structure consists of brick masonry walls in lime mortar. The walls are characterized by variable thickness, decreasing from 280 mm at the first-floor level to 150 mm at the second-floor level. There are brick masonry columns in the interior of the agricultural section at the second-floor level. The buttresses can be found in the exterior brick masonry walls. Both the residential and agricultural sections have wooden floors; there are vaulted floors in the central area. In some cases, composite floors made of steel beams and perforated bricks can be found. Although the building plan is very regular, the seismic performance of this building type is rather poor due to the vertical irregularity (offset of the floors in the residential and agricultural sections), the absence of connections between walls and between the walls and floors, the thrusting of the roof, and the deterioration of materials.

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