6/10/2015 World Housing Encyclopedia ­WHE

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World Housing Encyclopedia ­WHE

A Resource on construction in Earthquake Regions

HomeHousing Reports

General Information

BuildingType:

RC Structural Wall Building

Country: ColombiaAuthor(s): Luis G. Mejia

Juan C. Ortiz R.Laura I. Osorio G.

LastUpdated:RegionsWhereFound:

Buildings of this construction type can be found in the Andean and Caribbean regions of Colombia. Concrete shear wall buildings are found primarilyin the big cities of the Andean region: Bogota, Medellin, Cali, Pereira, Armenia, Manizales, Bucaramanga, and Ibague. Cities of the Caribbean region:Barranquilla, Cartagena, and Santa Marta). Approximately 2 percent of the housing in these cities is of this type. This building type is found principallyin densely populated urban areas where there is a need to provide many housing units in a relatively small area.

Summary:These buildings are characterized mainly by cast­in­place, load­bearing, reinforced­concrete shear ...

more

Length oftimepracticed:

25­60 years

StillPracticed:

Yes

In practiceas of:BuildingOccupancy:

Residential, 20­49 units

Typicalnumber ofstories:

7­20

Terrain­Flat:

Typically

Terrain­Sloped:

Typically

Comments: The main function of this building typology is multi­family housing. Actually, these buildings are often used for the constructi

Building Materials and Construction Process

Features Bldg Process SocEcon EQ Retrofit Refs

Additional reinforcement in shear walls intersection (plan). Photo courtesy of Alvaro PImage 5 of 16

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Description of Building Materials

StructuralElement

BuildingMaterial (s) Comment (s)

Wall/Frame Wall: reinforcedconcrete

Characteristic strength: f'c = 21 MPa to 35 MPa fy = 420 MPa Mixproportions/dimensions:1:1.5­1.8:2.5

Foundations reinforcedconcrete

Characteristic strength: f'c = 21 MPa fy = 420 MPa Mixproportions/dimensions:1:2:3

Floors reinforcedconcrete

Characteristic strength: f'c = 21 MPa to 28 MPa fy = 420 MPa Mixproportions/dimensions:1:1.8­2:2.5

Roof reinforcedconcrete

Characteristic strength: f'c = 21 MPa to 28 MPa fy = 420 MPa Mixproportions/dimensions:1:1.8­2:2.5

Other

Design Process

Who isinvolved withthe designprocess?

EngineerArchitect

Roles ofthoseinvolved inthe designprocess

Building design is done by architects and structural engineers. Both professions play the mostimportant role in each stage of the design and construction.

Expertise ofthoseinvolved inthe designprocess

Generally, in this kind of building, the design and construction are supervised by engineerspossessing proficiency and expertise. In every case, the project should be reviewed andapproved by a state agency and theoretically, by law, must be supervised during the constructionprocess by a contractor not associated with the construction firm.

Construction Process

Whotypicallybuilds thisconstructiontype?

Contractor

Roles ofthoseinvolved inthe buildingprocess

These buildings are typically built for housing projects by developers and then sold to the generalpopulation.

Expertise ofthoseinvolved inbuildingprocessConstructionprocess andphasing

Generally, a construction company buys the land and contracts with an architectural firm and astructural engineer to design the building. The construction process is simple; first, a design isapproved, and then the foundations, walls and slabs are built. It is very common today to use ametal formwork and build one story per week in a building with four units per story, but it can alsobe built completing one story per day depending on cash flow requirements. Equipment can be

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used to make the mix on site or this can be contracted with a pre­mix company. Placement can bedone manually by workers carrying the concrete in buckets, by pumping the concrete, or by acombination of both methods. The construction of this type of housing takes place in a singlephase. Typically, the building is originally designed for its final constructed size.

Constructionissues

Building Codes and Standards

Is thisconstruction typeaddress bycodes/standards?

Yes

Applicable codesor standards

This construction type is addressed by the codes/standards of the country. NSR­98 (NormasColombianas de y construccion Sismo Resistente) Colombian Code of Seismic ResistantDesign and Construction, 1998. The year the first code/standard addressing this type ofconstruction issued was CCCSR­84 (Codigo Colombiano de Construcciones SismoResistentes) Colombian Code of Seismic Resistant Construction, 1984. Prior to 1984, the ACIand UBC codes were widely used. NSR­98 is an accurate adaptation of ACI 318­95, with afew modifications in accordance with Colombian characteristics. Regulations found in ACI318, sections 10 and 11, are mandatory, and for moderate and high seismic areas, theregulations in chapter 21.6 are required, too. The most recent code/standard addressing thisconstruction type issued was 1998.

Process forbuilding codeenforcement

The building design and construction must follow the provisions of NSR­98. Permits arerequired to develop the project, but in some cases after the permits have been given, theowner or contractor changes some of the building characteristics (mainly, the layout plan)without the approval of the state organization that issued the permits.

Building Permits and Development Control Rules

Are building permits required? YesIs this typically informal construction? NoIs this construction typically authorized as per development control rules? YesAdditional comments on building permits and development control rules

Building Maintenance and Condition

Typical problems associated with this type of constructionWho typically maintains buildings of this type? Owner(s)Renter(s)Additional comments on maintenance and building condition

Construction Economics

Unitconstructioncost

The construction cost varies depending on the place and the economic class of the buyer. Forpoor people, in apartments of 45 m2 to 55 m2, the construction cost per square meter can bebetween 90 US/m2 to 100 US/m2. For middle­ to upper­middle­class people, in apartments of 70m2 to 85 m2, the construction cost per square meter can be between 130 US/m2 to 160 US/m2.The final cost per square meter for the purchaser of the unit can reach between 1.0 to 1.6 timesthe construction costs.

Laborrequirements

Today, it is common to find subsidized housing projects constructed in a short time. The structurefor a 7­ to 10­story building can be constructed within only 2.5 to 3.5 months depending of thefoundation type, and its delivery to the buyer can be practically immediate because of minimalnonstructural detailing. In 20­ to 25­story projects, the construction time for the structure isbetween 9 and 11 months, and the final delivery to the buyer is between 13 to 15 months.Generally, the construction time depends on the project's cash flow.

Additionalcommentssection 3

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This project was funded by a grant from the US Geological Survey.

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