Report # 101 : Tunnel form building

by Ahmet Yakut, Polat Gulkan

This type of rapidly constructed, multi-unit residential form has been used in Turkey since the late 1970s and early 1980s. It has demonstrated superior earthquake resistance and has also been increasingly utilized as permanent housing in post-earthquake reconstruction programs. Initially, the tunnel form building was targeted for multi-unit residential construction for public or privately sponsored housing projects. Typically, a single building may contain 15 or more stories and up to 40 or 50 residential units. This contribution has been motivated by our intention to not only familiarize readers with the architectural or structural features of the building type, but to also underscore its noteworthy seismic performance that stands in stark contrast to Turkey’s recent experience.


Report # 109 : Concrete Shear Wall Buildings

by Luis G. Mejia, Juan C. Ortiz R., Laura I. Osorio G.

These buildings are characterized mainly by cast-in-place, load-bearing, reinforced-concrete shear walls in both principal directions. The buildings are usually multiple housing units found in the major urban areas of Colombia, especially in the Andean and Caribbean regions. They represent about 2 to 3% of the housing stock in the cities with a population between one to seven million. These buildings typically have 7 to 20 stories, generally with a cast-in-place reinforced-concrete floor slab system. In general, these buildings have good seismic performance because of their regular mass distribution in height and symmetrical plan configuration and the great stiffness and strength of the walls that can restrict story drift to less than or equal to 0.005h. In some cases, if the buildings were constructed after the first Colombian Seismic Code in 1984, poor seismic detailing is found.


Report # 87 : Block of flats with 11 floors out of cast-in-situ concrete, gliding frameworks

by Maria D. Bostenaru

This is an urban high-rise, built in Romanian cities, especially in Bucharest, during the Communist era. Romania is known as a seismically prone area. The epicenter of damaging earthquakes is near Vrancea and can affect half of the country at one time. Earthquakes higher than magnitude 7.0 on the Richter scale occur once in 30 years. Bucharest, the capital, is located on the banks of the Dâmbovita and Colentina rivers, on non-homogeneous alluvial soil deposits, around 150 km south of the epicenter in the main direction of the seismic wave propagation. This construction type is another example of a building with reinforced concrete shear walls. Unlike the OD type, described in report #78, this construction has more than just a single load-bearing wall in the longitudinal direction, and thus the behavior of the building under seismic loads is significantly improved. These exclusively residential buildings are found in large green-belt areas, in peripheral neighborhoods, either as an isolated building or in groups. Having uniform height and rectangular form, they generally contain four units on a floor. Characteristically, there is a ground floor with either 4 or 10 upper floors. This example is the Y-type, with 10 upper floors. The structural type is the “Fagure” (honeycomb) one, commonly used in Romanian construction practice. Although the perimeter walls are load-bearing, there are wide openings in them. During the earthquake of 4 March 1977 (Richter magnitude 7.2), over 30 buildings collapsed in Bucharest and killed 1,424 people. This type of building behaved rather well, with only superficial damage observed. Seismic strengthening was thus limited to repairs, where necessary.


Report # 79 : Concrete shear wall highrise buildings

by John Pao, Svetlana N. Brzev

This concrete shear wall high-rise represents a contemporary residential and commercial construction commonly found in downtown areas of Canadian cities. This multi-family building contains 100 to 200 units and provides housing for 300 to 500 inhabitants. The height of these buildings is variable and usually ranges from 12 to 35 stories. The lateral load-resisting system consists of reinforced concrete shear walls and concrete floor slabs. The gravity load is carried mainly by concrete columns. Seismic detailing of shear walls in medium-to-high seismic regions is mandatory per the Canadian Concrete Code. Exterior walls are clad in stucco backed by cold-form steel framing or masonry veneer, steel/glazing panels, or precast panels. There is no report on the damage sustained by this building type in past earthquakes in Canada. However, because these buildings are designed according to state-of-the-art seismic codes, their seismic performance is expected to be satisfactory in an earthquake of design intensity (per the seismic design requirements of the National Building Code of Canada).


Report # 78 : Reinforced concrete cast-in situ shear wall buildings (“OD”-type, with “fagure” plan)

by Maria D. Bostenaru, Ilie Sandu

This is typical urban multi-family housing practiced throughout Romania in the period from 1965 to 1989. There are many existing buildings of this type at the present time, with about 8,000 apartments in Bucharest alone. Concrete shear wall construction is commonly used for the residential construction and it accounts for over 60% of new housing. Buildings of this type are typically 10 or 11 stories high. The main load-bearing structure is a cast in-situ concrete shear wall structure supported by RC solid slabs. Each building block consists of several (5-6) identical building units (“tronsons” in Romanian) separated by means of seismic joints. The walls are continuous throughout the building height and orientated in two directions, with only one centrally located wall in the longitudinal direction and eight walls in the transverse direction. In addition, there are some lightweight concrete partition walls. This building plan is known as the honeycomb (“fagure”) plan. The buildings are often supported by mat foundations due to soft (alluvial) soil conditions. Many buildings of this type were designed according to the 1963 Romanian Building Code (P13-1963) which was updated in 1970 (P13-1970). The 1963 Code considered a magnitude 7 design earthquake for the Bucharest area. This region is well known as a seismically prone area, with the epicentre of damaging earthquakes close to Vrancea. Earthquakes with the Richter magnitude of over 7.0 occur once in 30 years. Bucharest, the capital, is located around 150 km south of the epicentre 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 river, 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. The buildings of “OD” type suffered damages of various extent in the 1977 earthquake, and one building unit (“tronson”) totally collapsed (that was the only shear wall building that collapsed in the FIGURE 1A: Typical Building Page 1 earthquake). Buildings with their longitudinal direction aligned parallel with the direction of seismic waves were most affected. The earthquake action in 1977 was mainly in NNE-SSV direction. Out of 167 building units (“tronson”s) of the “OD” type existing in Bucharest at the time of the 1977 earthquake, only 7 were lightly damaged; the remaining building units suffered a partial collapse (7 units) or damages (19 were significantly damaged, 72 were moderately damaged, and 61 were lightly damaged). According to the reports, damages to this construction type were due to inadequate wall density in the longitudinal direction, inadequate amount and detailing of wall reinforcement, lack of lateral confinement in the walls and in the boundary elements (“bulbs”) causing brittle concrete failure and buckling of reinforcement. In addition, the quality of concrete construction was found to be rather poor.


Report # 40 : Buildings with cast in-situ load-bearing reinforced concrete walls

by Svetlana Uranova, Ulugbek T. Begaliev, V. Manukovskiy

Buildings with cast-in-situ load-bearing reinforced concrete walls are widespread in many republics of the former Soviet Union. There are many such buildings in Kyrgyzstan in areas with a design seismicity of 8 and 9 on the MSK scale. The buildings with cast-in-situ walls are typically medium- to high-rise buildings (4-18 stories high; often 12-stories high). High-rise buildings of this type (9-18 stories high) have basements. The load-bearing structure consists of cast-in-situ reinforced concrete walls and precast reinforced concrete floor slabs. Floor slabs are either two-way solid slab structures, or, less often, hollow-core slabs. These buildings do not have any frame elements (columns and beams). Facade walls are usually made of lightweight (ceramsite) concrete. The buildings are supported by concrete strip or mat foundations. This building type is considered to be earthquake-resistant. Problems are mainly related to the quality of construction.


Report # 38 : Prefabricated concrete panel buildings with monolithic panel joints

by Svetlana Uranova, Ulugbek T. Begaliev

Prefabricated concrete panel building construction with monolithic panel joints has been practiced throughout the former Soviet Union (including Kyrgyzstan) since 1965. This type of prefabricated construction is known as seria 105. Apartment buildings of this type are usually 5-9 stories high. The foundations are made of cast in-situ reinforced concrete. Steel dowels are provided in the foundations to ensure anchorage of steel rebars located in the panels and in the panel joints. The load-bearing structure in large panel buildings consists of reinforced concrete panels combined to form a box-type rigid system by means of special joints. This building type is considered to be one of the most earthquake-resistant construction types in the former Soviet Union.


Report # 32 : Prefabricated large panel concrete buildings with two interior longitudinal walls.

by Igor E. Itskov, Ashimbayev M. Umarbayevich, Nikolai B. Chernov

This is a typical urban residential construction type commonly found in the southern part of Kazakhstan. Typical buildings of this type are 5- or 9-stories high. This is a prefabricated large panel construction typical for the post-Soviet Union. Large panel buildings with two interior longitudinal walls (as described in this contribution) were developed in Kazakhstan and were specifically designed for the areas of high seismic hazard (intensity 9 and higher per MSK scale). It is considered that this building type (with two interior longitudinal walls) is superior as compared to other large panel building types (usually characterized with one longitudinal wall only) in terms of seismic resistance. The load-bearing system consists of precast reinforced concrete walls and floor panels. All precast members are joined in a box-type structure by means of panel joints. Facade walls are usually made of 2 exterior layers of low-strength lightweight (ceramsite) concrete with good thermal insulation properties and the interior layer of normal-weight concrete. Large panel buildings are generally well-known for their good seismic resistance, which is mainly due to the large rigidity and high degree of redundancy. The fundamental period of vibration for a 9-story building of this type is approximately 0.35-0.4 sec. Large panel buildings of a similar construction (with one longitudinal interior wall) existed in Armenia at the time of the 1988 Spitak earthquake and they remained undamaged, whereas other precast construction types (mainly concrete frame construction) had suffered significant damage and/or collapse. Although the buildings of this type have not been exposed to major damaging earthquakes in Kazakhstan as yet, their dynamic performance was evaluated by means of harmonic forced vibration tests simulating earthquake effects. The buildings subjected to these tests did not experience any damage.


Report # 4 : Concrete Shear Wall Buildings

by Ofelia Moroni, Cristian Gomez

This housing type is mainly characterized by reinforced concrete shear walls that are built in both directions along the entire height. Some of the walls may be perforated with openings (coupled walls). These buildings are multiple housing units and are found in the major urban areas in Chile. Stiffness and mass distribution are regular and most of them may have a symmetry axis in at least one direction of the plan. In general, these buildings are quite stiff because they must resist a base shear of 5-6.7% (depending on the seismic zone) and the story drift must be equal to or less than 0.002. Seismic performance is very good, strength and stiffness are controlled, and torsional effects are minimal. The buildings may have one or two basement floors. Problems that may appear in the future include reduction in the wall density, introduction of soft floor, or torsional effects.