World Housing Encyclopedia Report

Country: Kyrgyzstan

Housing Type: Buildings with hollow clay tile load-bearing walls and precast concretefloor slabs

Contributors:Ulugbek T. BegalievSvetlana Uranova

Primary Reviewer:Svetlana Brzev

Created on: 6/5/2002Last Modified: 7/2/2003

This encyclopedia contains information contributed by various earthquake engineering professionalsaround the world. All opinions, findings, conclusions, and recommendations expressed herein are those

of the various participants, and do not necessarily reflect the views of the Earthquake EngineeringResearch Institute, the International Association for Earthquake Engineering, the Engineering Information

Foundation, John A. Martin & Associates, Inc. or the participants' organizations.

Table of Contents

General Information............................................................................................1Architectural Features........................................................................................ 3Socio-Economic Issues...................................................................................... 4Structural Features............................................................................................. 6Evaluation of Seismic Performance and Seismic Vulnerability.......................... 10Earthquake Damage Patterns............................................................................ 12Building Materials and Construction Process..................................................... 13Construction Economics.....................................................................................15Insurance............................................................................................................16Seismic Strengthening Technologies................................................................. 17References......................................................................................................... 18Contributors........................................................................................................ 19Figures................................................................................................................20

1 General Information

1.1 CountryKyrgyzstan

1.3 Housing TypeBuildings with hollow clay tile load-bearing wallsand precast concrete floor slabs

1.4 SummaryBuildings of this type are characterized withload-bearing masonry walls and precastconcrete floors. Typical buildings of this type are3 to 4-story high and they are characterized withthe two longitudinal walls and several crosswalls.There are many existing buildings of thistype in the Kyrgyzstan, and most of them wereconstructed in the 1960's. This constructionpractice was banned after 1966, due to theCode provisions which required restricted size ofcores in hollow clay tiles (blocks). The exteriorwalls are made of hollow clay masonry tiles(blocks). In some cases there are two wallwythes: the exterior wythe made of hollow claytiles and the interior wythe made of solid claybricks. Floor system consists of precastreinforced concrete hollow core slabs. Buildingsof this type were built in the areas with highseismic design intensity (8, 9 and higher on theMSK scale). This building type is considered tobe rather vulnerable to seismic effects.

FIGURE 1: Typical Building

1.5 Typical Period of Practice for Buildings of This Construction TypeHow long has thisconstruction been practiced< 25 years< 50 years< 75 years X< 100 years< 200 years> 200 years

Is this construction still being practiced? Yes NoX

1.6 Region(s) Where UsedMany existing buildings of this type can be found throughout the Kyrgyzstan, most of them were built inurban areas.

1.7 Urban vs. Rural ConstructionWhere is this construction commonly found?In urban areas XIn rural areasIn suburban areas

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Both in rural and urban areas

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2 Architectural Features

2.1 OpeningsTypical window size is 1.2 m X 1.2 m. Typical door size is 0.9 m (width) X 1.9 m (height). The overallwindow and door area accounts for 10 to 12% of the overall wall surface area.

2.2 SitingYes No

Is this type of construction typically found on flat terrain? XIs this type of construction typically found on sloped terrain? (hilly areas) XIs it typical for buildings of this type to have common walls with adjacentbuildings?

X

The typical separation distance between buildings is 10 meters

2.3 Building ConfigurationTypical shape of a building plan for this housing type is rectangular.

2.4 Building FunctionWhat is the main function for buildings of this type?Single family houseMultiple housing units XMixed use (commercial ground floor, residential above)Other (explain below)

2.5 Means of EscapeThere is one staircase in each building unit. Building unit consists of 4 apartments (housing units) on eachfloor. Each building consists of 2 to 4 building units.

2.6 Modification of BuildingsThere are lot of modifications at the ground floor level in buildings of this type. Typical modificationsinclude installation of new door and windows openings, complete/partial removal of existing walls, andhorizontal extension (addition of rooms).

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3 Socio-Economic Issues

3.1 Patterns of OccupancyEach floor in the building consists of 2 to 4 housing units. One family occupies one housing unit.Depending on the number of building units and stories, 32 to 64 families occupy one building.

3.2 Number of Housing Units in a Building64 units in each building.

Additional Comments: Usually there are 32-64 units in each building.

3.3 Average Number of Inhabitants in a BuildingHow many inhabitants reside in a typical building of thisconstruction type?

During the day / businesshours

During the evening / night

< 55 to 1010-20> 20 X XOther

3.4 Number of Bathrooms or Latrines per Housing UnitNumber of Bathrooms: 1Number of Latrines: 0

3.5 Economic Level of InhabitantsEconomic Status House Price/Annual Income

(Ratio)Very poor /Poor X /Middle Class X /Rich /

Additional Comments: 80% poor, 20% middle class

3.6 Typical Sources of FinancingWhat is the typical source of financing for buildings of this type?Owner FinancedPersonal Savings XInformal Network: friends and relativesSmall lending institutions/microfinance institutionsCommercial banks / mortagesInvestment poolsCombination (explain)Government-owned housing XOther

Additional Comments: Before 1990 all kind construction has typical Government source of financing. Nowall existing apartment buildings are private.

3.7 Ownership

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Type of Ownership/OccupancyRentOwn outright XOwn with Debt (mortgage or other)Units owned individually (condominium) XOwned by group or poolLong-term leaseOther

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4 Structural Features

4.1 Lateral Load-Resisting SystemLateral load-resisting system consists of the exterior walls of small-size clay block masonry and theinterior brick masonry walls. The exterior walls are made of hollow clay masonry tiles (blocks). The blockdimensions are: 138 mm (height) X 120 mm X 250 mm. The blocks have oval hollow cores (90 mm X 16mm). The area of the cores accounts for 25-33 % of the block area. Due to the large area of hollow cores,masonry is characterized with rather low tensile resistance. Usually mortar is of a poor quality. In somecases, exterior walls consist of two wythes; the exterior wythe is made of hollow clay tiles, whereas theinterior wythe is made of solid bricks (dimensions 250 mm thickness X 120 mm X 70 mm). Floor systemconsists of precast reinforced concrete hollow core slabs. Dimensions of slab panels are 5.86 m length X1.2 m width. The panels are combined in the uniform diaphragm by means of reinforced concrete belt(cast in-situ reinforced concrete beam). Windows and door lintels are of precast concrete construction.

4.2 Gravity Load-Bearing StructureGravity load-bearing structure consists of loadbearing masonry walls and concrete floor slabs.

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4.3 Type of Structural SystemMaterial Type of

Load-BearingStructure

# Subtypes

Masonry Stone masonrywalls

1 Rubble stone (field stone) in mud/lime mortar or withoutmortar (usually with timber roof)

2 Massive stone masonry (in lime or cement mortar)Earthen walls 3 Mud walls

4 Mud walls with horizontal wood elements5 Adobe block or brick walls6 Rammed earth/Pise construction

Unreinforced brickmasonry walls

7 Unreinforced brick masonry in mud or lime mortar8 Unreinforced brick masonry in mud or lime mortar with

vertical posts9 Unreinforced brick masonry in cement or lime mortar

(various floor/roof systems)X

Confined masonry 10 Confined brick/block masonry with concrete posts/tiecolumns and beams

Concrete blockmasonry walls

11 Unreinforced in lime or cement mortar (various floor/roofsystems)

12 Reinforced in cement mortar (various floor/roof systems)13 Large concrete block walls with concrete floors and roofs

Concrete Moment resistingframe

14 Designed for gravity loads only (predating seismic codes i.e.no seismic features)

15 Designed with seismic features (various ages)16 Frame with unreinforced masonry infill walls17 Flat slab structure18 Precast frame structure19 Frame with concrete shear walls-dual system20 Precast prestressed frame with shear walls

Shear wall structure 21 Walls cast in-situ22 Precast wall panel structure

Steel Moment resistingframe

23 With brick masonry partitions24 With cast in-situ concrete walls25 With lightweight partitions

Braced frame 26 Concentric27 Eccentric

Timber Load-bearingtimber frame

28 Thatch29 Post and beam frame30 Walls with bamboo/reed mesh and post (wattle and daub)31 Wooden frame (with or without infill)32 Stud wall frame with plywood/gypsum board sheathing33 Wooden panel or log construction

Various Seismic protectionsystems

34 Building protected with base isolation devices or seismicdampers

Other 35

Additional Comments: Masonry walls are made of hollow clay tiles.

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4.4 Type of FoundationType Description

Shallow Foundation Wall or column embedded in soil, without footingRubble stone (fieldstone) isolated footingRubble stone (fieldstone) strip footingReinforced concrete isolated footingReinforced concrete strip footing XMat foundationNo foundation

Deep Foundation Reinforced concrete bearing pilesReinforced concrete skin friction pilesSteel bearing pilesWood pilesSteel skin friction pilesCast in place concrete piersCaissons

Other

4.5 Type of Floor/Roof SystemMaterial Description of floor/roof system Floor Roof

Masonry VaultedComposite masonry and concrete joist

StructuralConcrete

Solid slabs (cast in place or precast)Cast in place waffle slabsCast in place flat slabsPrecast joist systemPrecast hollow core slabsPrecast beams with concrete toppingPost-tensioned slabs

Steel Composite steel deck with concrete slabTimber Rammed earth with ballast and concrete or plaster finishing

Wood planks or beams with ballast and concrete or plaster finishingThatched roof supported on wood purlinsWood single roofWood planks or beams that support clay tilesWood planks or beams that support slate, metal asbestos-cement or plasticcorrugated sheets or tilesWood plank, plywood or manufactured wood panels on joists supported bybeams or walls

Structuralconcrete

Precast hollow core concrete slabs X X

4.6 Typical Plan DimensionsLength: 60 - 60 metersWidth: 60 - 60 meters

4.7 Typical Number of Stories4

4.8 Typical Story Height2.7 meters

4.9 Typical Span6 meters

Additional Comments: Typical distance between the cross walls ranges from 2.8 m to 6 m, whereas thedistance between longitudinal walls is 12 m.

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4.10 Typical Wall Density0.07% - 0.08%7 to 8%.

4.11 General Applicability of Answers to Questions in Section 4This contribution is a generic description of a particular construction type.

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5 Evaluation of Seismic Performance and Seismic Vulnerability

5.1 Structural and Architectural Features: Seismic ResistanceStructural/ArchitecturalFeature

Statement True False N/A

Lateral load path The structure contains a complete load path for seismic force effects fromany horizontal direction that serves to transfer inertial forces form thebuilding to the foundation.

X

Buildingconfiguration

The building is regular with regards to both the plan and the elevation. X

Roof construction The roof diaphragm is considered to be rigid and it is expected that the roofstructure will maintain its integrity, i.e.. shape and form, during anearthquake of intensity expected in this area.

X

Floor construction The floor diaphragm(s) are considered to be rigid and it is expected that thefloor structure(s) will maintain its integrity, during an earthquake of intensityexpected in this area.

X

Foundationperformance

There is no evidence of excessive foundation movement (e.g. settlement)that would affect the integrity or performance of the structure in anearthquake.

X

Wall and framestructures-redundancy

The number of lines of walls or frames in each principal direction is greaterthan or equal to 2.

X

Wall proportions Height-to-thickness ratio of the shear walls at each floor level is: 1) Lessthan 25 (concrete walls); 2)Less than 30 (reinforced masonry walls); 3)Less than 13 (unreinforced masonry walls).

X

Foundation- wallconnection

Vertical load-bearing elements (columns, walls) are attached to thefoundations; concrete columns and walls are doweled into the foundation.

X

Wall-roofconnections

Exterior walls are anchored for out-of-plane seismic effects at eachdiaphragm level with metal anchors or straps.

X

Wall openings The total width of door and window openings in a wall is: 1) for brickmasonry construction in cement mortar: less than 1/2 of the distancebetween the adjacent cross walls; 2) for adobe masonry, stone masonryand brick masonry in mud mortar: less than 1/3 of the distance between theadjacent cross walls; 3) for precast concrete wall structures: less than 3/4 ofthe length of a perimeter wall.

X

Quality of buildingmaterials

Quality of building materials is considered to be adequate per requirementsof national codes and standards (an estimate).

X

Quality ofworkmanship

Quality of workmanship (based on visual inspection of few typical buildings)is considered to be good (per local construction standards).

X

Maintenance Buildings of this type are generally well maintained and there are no visiblesigns of deterioration of building elements (concrete, steel, timber).

X

Other

5.2 Seismic FeaturesStructural Element Seismic Deficiency Earthquake-Resilient Features Earthquake Damage PatternsWall - Exterior walls (hollow clay tiles) have

poor shear and tensile resistance. -Large unsupported length of the crosswalls. - Poor quality of masonry mortar.- Absence of wall reinforcement.

Diagonal cracks in wall, cracks at thewall corners, out-of-plane collapsewalls, partial or complete collapse ofbuildings

Frame (columns,beams)Roof and floors

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5.3 Seismic Vulnerability RatingVulnerability

High (Very PoorSeismicPerformance)

Medium Low (ExcellentSeismicPerformace)

A B C D E FSeismic

Vulnerability Class< 0 >

0 - probable value< - lower bound> - upper bound

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6 Earthquake Damage Patterns

6.1 Past Earthquakes Reported To Affect This ConstructionYear Earthquake Epicenter Richter magnitude(M) Maximum Intensity (Indicate

Scale e.g. MMI, MSK)1992 Suusamir (Kyrgyzstan) 7.4 7 (MSK)1988 Spitak (Armenia) 7 10 (MSK)1986 Kairakum (Kyrgyzstan,

Tadjikistan)6.8 7 (MSK)

Additional Comments: Damage to walls: inclined and diagonal cracks in the piers, destruction of buildingcorners, partial collapse of walls.

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7 Building Materials and Construction Process

7.1 Description of Building MaterialsStructural Element Building Material Characteristic Strength Mix Proportions/ Dimensions CommentsWalls Masonry Tension resistance of mortar

less 60 MPamortar mix 1:12(cement/sand) and less

(different, dependon mix materials)

Foundations Concrete 5-7 MPa (cube compressivestrength)

1:3:6 (different, dependon mix materials)

FrameRoof and floors 30-35 MPa ( cube

compressive strength) Steel:flow limit 390 MPa ElasticityModulus 200,000 MPa)

1:1,7:3,2 (different depend ontype of mix materials)

OtherOther

7.2 Does the builder typically live in this construction type, or is it more typicallybuilt by developers or for speculation?Anyone can live in buildings of this construction type

7.3 Construction ProcessThese buildings are constructed by contractors. Design institutes develop design documentation. Specialconstruction companies perform construction. Precast elements and bricks are made at the plant. Mainequipment for construction is: crane, welding equipment and concrete mixers.

7.4 Design/Construction ExpertiseExpertise is necessary for the design and the different stages of construction according to the laws of theKyrgyz Republic.

7.5 Building Codes and StandardsYes No

Is this construction type addressed by codes/standards? X

Title of the code or standard: 1957Year the first code/standard addressing this type of construction issued: SN-8-57.Building norm andguiding principles in seismic regions, SNiP II-A.12-62 Building in seismic regions:Design codes.National building code, material codes and seismic codes/standards: SNiP II-7-81. Building in SeismicRegions - Design codeWhen was the most recent code/standard addressing this construction type issued? 1981

7.6 Role of Engineers and ArchitectsEngineers play a leading role in each stage of construction.

7.7 Building Permits and Development Control RulesYes No

Building permits are required XInformal construction XConstruction authorized per development control rules X

7.8 Phasing of ConstructionYes No

Construction takes place over time (incrementally) XBuilding originally designed for its final constructed size X

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7.9 Building MaintenanceWho typically maintains buildings of this type?Builder XOwner(s)Renter(s) XNo oneOther

7.10 Process for Building Code EnforcementBuilding permit will be given if the design documents have been approved by the State Experts. StateExperts check the compliance of design documents with the pertinent Building Codes. According to thebuilding bylaws, the building cannot be used without the formal appoval of a special committee.Thecommittee grants the approval (permit) if design documents are complete and the construction has beencarried out in compliance with the Building Codes.

7.11 Typical Problems Associated with this Type of ConstructionThe problems are associated with the use of hollow clay tiles (blocks) for loadbearing walls, large span forcross walls, and poor quality of construction.

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8 Construction Economics

8.1 Unit Construction Cost (estimate)For load-bearing structure only: about 150 US$/m²

8.2 Labor Requirements (estimate)It would take from 12 to 24 months for a team of 15 workers to build the structure only (without finishes).

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9 Insurance

9.1 Insurance IssuesYes No

Earthquake insurance for this construction type is typically available XInsurance premium discounts or higher coverages are available for seismicallystrengthened buildings or new buildings built to incorporate seismically resistantfeatures

X X

9.2 If earthquake insurance is available, what does this insurance typicallycover/cost?

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10 Seismic Strengthening Technologies

10.1 Description of Seismic Strengthening ProvisionsType of intervention Structural Deficiency Description of seismic strengthening provision usedRetrofit(Strengthening)

Poor shear and tensile resistance ofhollow clay tile walls

Installation of reinforced concrete overlay (FIGURES 6A and 6B)

New Construction

Additional Comments: Seismic strengthening provisions are included in the official design guidelines,however it is rarely practiced in Kyrgyzstan.

10.2 Has seismic strengthening described in the above table been performed indesign practice, and if so, to what extent?No.

10.3 Was the work done as a mitigation effort on an undamaged building, or asrepair following earthquake damage?Very few buildings of this type were strengthened in Kygyzstan. Buildings in Bishkek have beenstrengthened as a part of building expansion project.

10.4 Was the construction inspected in the same manner as new construction?Yes.

10.5 Who performed the construction: a contractor, or owner/user? Was anarchitect or engineer involved?The construction was performed by contractor. Usually engineers participate in the design and superviseconstruction process.

10.6 What has been the performance of retrofitted buildings of this type insubsequent earthquakes?Strengthened buildings were not subjected to the effects of strong earthquakes as yet.

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11 ReferencesSeismic Hazard and Buildings Vulnerability in Post-Soviet Central Asia Republics. Edited by Stephanie A.King, Vitaly I. Khalturin and Brian E. Tucker. Kluwer Academic Publishers, P.O. Box 17, 3300 AADordrecht, The Netherlands. (Proceeding of the NATO Advanced Research Workshop on EarthquakeRisk Management Strategies for Post-Soviet Central Asian Republics. Almaty, Kazakhstan, 22-25October 1996)

Building and Construction Design in Seismic Regions. Handbook. Uranova S.K., Imanbekov S.T#KyrgyzNIIPStroitelstva, Building Ministry Kyrgyz Republic.Bishkek.1996

SNiP II-7-81* Building in seismic regions. (Building Code). Moscow, 1981. Klyachko M. A. Earthquakesand Us. Intergraf, Saint Peterburg, Russia, 1999 (in Russian).

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12 ContributorsName Ulugbek T. Begaliev Svetlana UranovaTitle Head of Department EngineerAffiliation KNIIPCAddress Vost Prom ZoneCholponatisky 2 107-1222 Harwood StreetCity Bishkek Vancouver, BCZipcode 720571 V6E 152Country Kyrgyzstan CanadaPhone 996-3312-237564 604-696-0563FaxEmail utbegaliev@yahoo.com uransv@yahoo.comWebpage

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13 Figures

FIGURE 1: Typical Building

FIGURE 2A: Key Load-Bearing Elements

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FIGURE 2B: A typical hollow clay tile (block) dimensions

FIGURE 3: Plan of a Typical Building

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FIGURE 4: Critical Structural Details: wall section showing concrete bond beam

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FIGURE 5A: A Photograph Illustrating Typical Earthquake Damage 1988 Spitak, Armenia earthquakeSource: EERI

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FIGURE 5B: Building Collapse in the 1988 Spitak, Armenia Earthquake (Source: Klyachko, 1999)

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FIGURE 6A: Illustration of Seismic Strengthening Techniques

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FIGURE 6B: Seismic strengthening under construction

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