Report #: 66

Report Date:

Country: UZBEKISTAN

Housing Type:

Housing Sub-Type:

Author(s): Shamil Khakimov, Bakhtiar Nurtaev

Last Updated:

Regions Where Found: Buildings of this construction type can be found in Tashkent and other cities of Uzbekistan and Central Asia. In Tashkent, this housing type accounts for over 18% of the residential building stock and for over 25% of the public building stock. This type of housing construction is commonly found in urban areas.

Summary: 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 loadresisting (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.

Length of time practiced: 25-60 years

Still Practiced: Yes

In practice as of:

Building Occupancy: Residential, 50+ units

Typical number of stories: 9-12

Terrain-Flat: Typically

Terrain-Sloped: 3

Comments:

This traditional construction practice has been followed for over 35 years. The frame panel seria IIS-04 was first used in 1973.

Plan Shape: Rectangular, solid

Additional comments on plan shape:

Typical plan length (meters): 24

Typical plan width (meters): 15

Typical story height (meters): 3

Type of Structural System: Structural Concrete: Precast Concrete: Moment frame

Additional comments on structural system: The vertical load-resisting system is reinforced concrete moment resisting frame. The gravity load-bearing structure consists of reinforced concrete frame, including precast columns and beams and precast floor panels.

The lateral load-resisting system is reinforced concrete moment resisting frame. The lateral load-resisting system is reinforced concrete frame, which consists of precast columns and beams and cast in-situ or precast concrete shear walls. Precast frame elements are joined together in the space frame structure. Shear walls may be made of precast panels or cast in-situ elevator cores in the taller buildings of this type (e.g., 12-story buildings). In medium-rise buildings of this type (e.g., 4-5 stories), the entire lateral load-resisting system consists of a RC frame only (i.e., shear walls are not present). Precast floor panels are joined in a rigid diaphragm for the distribution of lateral forces.

Gravity load-bearing & lateral load-resisting systems:

Typical wall densities in direction 1: 4-5%

Typical wall densities in direction 2: 4-5%

Additional comments on typical wall densities: The typical structural wall density is up to 5%.

Wall Openings: Usually a rectangular plan. In this housing type, the main load-bearing elements are the columns, beams and joints (a frame structure). Therefore, seismic vulnerability does not depend on the number and size of the openings. The size of the windows and doors ranges from 2.25 m to 4.5 m.

Is it typical for buildings of this type to have common walls with adjacent buildings?: No

Modifications of buildings: Minor modifications of interior partition walls may be done by the owners.

Type of Foundation: Shallow Foundation: Reinforced concrete isolated footingShallow Foundation: Reinforced concrete strip footing

Additional comments on foundation:

Type of Floor System: Other floor system

Additional comments on floor system: Structural concrete: Hollow core slab (precast)

Type of Roof System: Roof system, other

Additional comments on roof system: Structural concrete: Hollow core slab (precast)

Additional comments section 2: When separated from adjacent buildings, the typical distance from a neighboring building is 30 meters.

Typical Plan Dimensions: Typical plan dimensions: 18x18m, 12x36m, 15x24m Typical Span: The typical span may be either 6 or 3 meters.

Who is involved with the design process?: EngineerArchitectOther

Roles of those involved in the design process:

Expertise of those involved in the design process:

Who typically builds this construction type?: OwnerBuilderOther

Roles of those involved in the building process: A builder may live in this construction type, and his children may attend the schools housed in buildings of this type. Typically, frame panel buildings are constructed by order of the municipality.

Expertise of those involved in building process:

Construction process and phasing: Based on the order of the government, a design agency develops a series of industrialized construction elements. Based on the information provided by the design agency, a concrete plant prepares a set of metal forms for the columns, girders, diaphragms, slabs, wall panels, staircases, etc., corresponding to the requirements of a series. Based on the order of a municipality or other clients, design firms develop designs of individual buildings or typical (standardized) building designs. A concrete plant manufactures and delivers all required building elements to the construction site. A construction company erects the building at the construction site. The main pieces of equipment used for the construction are a tower crane, welding equipment, and concrete mixers. The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size.

Construction issues

Is this construction type address by codes/standards?: Yes

Applicable codes or standards: The construction is carried out based upon the catalogs of frame panel seria IIS-04 (developed in 1973), and upon the National Building Code of Uzbekistan: “Construction in Earthquake-prone Areas” (KMK.2.01.03-96). National Building Code, Material Codes and Seismic Codes/Standards; National Building Code of Uzbekistan: Construction in Earthquake-prone Areas (KMK.2.01.03-96). The most recent code/standard addressing this construction type issued was 1996.

Process for building code enforcement: Design of buildings using the seria IIS-04 is carried out in accordance with the National Building Code of Uzbekistan: Construction in Earthquake-prone Areas.

All designs are reviewed by the State Expert Bureau of the State Committee on Architecture and Construction (SCAC); the revisions are incorporated in the final design (if required). Once the review is completed, the designs are forwarded to the concrete plants and the construction company. The concrete strength is evaluated in the laboratory in the concrete plant, and the reinforcement schedule is checked and compared with the design documents. Periodically (once in six months), the laboratory data are examined by a representative of the State Architecture Construction Control Department (SACC) of SCAC. SCAC also monitors the construction quality at the site. In addition to this, a representative of the design agency or firm also performs a site inspection. The builders should take into account the designer's comments made during the site inspection. Once the construction is complete, a special state expert committee needs to approve the building and to issue the building permit. Use and selection of the typical, standard production of series IIS-04 depend upon load conditions. Engineers and architects cannot change any construction details (joints, connections) in the existing series, which is approved by the government. Only the agency that has developed the series is able to change the details.

Are building permits required?: Yes

Is this typically informal construction?: No

Is this construction typically authorized as per development control rules?: Yes

Additional comments on building permits and development control rules:

Typical problems associated with this type of construction:

Who typically maintains buildings of this type?: Owner(s)Renter(s)

Additional comments on maintenance and building condition:

Unit construction cost: 33000 sum/m# (110 US$/m#).

Labor requirements: A 12-story residential building with 48 housing units and with plan dimensions18x18 m may be erected by 10 workers in 10 months.

Additional comments section 3:

Damage patterns observed in past earthquakes for this construction type: Buildings of this type were damaged during the 1988 Spitak earthquake, as illustrated in Figures 6 and 7.

Additional comments on earthquake damage patterns: Due to poor quality of wall-column and wall-beam joints, the walls may experience serious damage in an earthquake.

Damage to beam-column joints

Damage of horizontal panel joints and the subsequent loss of rigid diaphragm behavior

Failure of precast diaphragm-to-frame connections.

The main reference publication used in developing the statements used in this table is FEMA 310 Handbook for the Seismic Evaluation of Buildings-A Pre-standard, Federal Emergency Management Agency, Washington, D.C., 1998.

The total width of door and window openings in a wall is: For brick masonry construction in cement mortar : less than ½ of the distance between the adjacent cross walls; For adobe masonry, stone masonry and brick masonry in mud mortar: less than 1/3 of the distance between the adjacent cross walls; For precast concrete wall structures: less than 3/4 of the length of a perimeter wall.

Additional comments on structural and architectural features for seismic resistance: Precast floor panels are constructed w ith special grooves and steel dow els projected on all four sides for achieving the cast in-situ joint. This type of floor structure subjected to lateral loads w as tested in the lab. The roof diaphragm is considered to be rigid provided that the quality of construction is adequate.

Vertical irregularities typically found in this construction type: Other

Horizontal irregularities typically found in this construction type: Other

Seismic deficiency in walls: Exterior and interior partition walls are non-load-bearing (i.e., they carry their own weight only).

Seismic deficiency in frames: The most vulnerable parts of a frame are beam-column joints; these welded joints are located in the area of extremely high loads. As a result of the welding, steel reinforcement bars may have loose ductility. Also, the concrete poured in these joints is often poorly vibrated.

Seismic deficiency in roof and floors: The joints between the precast slabs (grouted in-situ) are sometimes not properly filled with grout and may lose their strength in an earthquake.

Other seismic deficiencies: Wall panels, (vertical diaphragms) The assembled reinforced concrete diaphragms are inadequately welded to the columns. Vertical bars discontinued during the site installation. Due to poor quality of construction, the diaphragm strength may be reduced by 50%.

For information about how seismic vulnerability ratings were selected see the Seismic Vulnerability Guidelines

Additional comments on seismic strengthening provisions: Seismic strengthening of a building in Tashkent is illustrated in Figures 12 and 13.

Has seismic strengthening described in the above table been performed?: Yes. Seismic strengthening was performed on some buildings in Tashkent.

1. Construction in Earthquake-prone Areas National Building Code of Uzbekistan, KMK 2.01.03-96 1996

2. Concrete and Reinforced Concrete - Design Codes and Standards

3. Construction Catalog: seria IIS-04.16

4. Earthquakes and Us Klyachko,M.A Intergraf, Saint Peterburg, Russia (in Russian) 1999