Description

The World Housing Encyclopedia (WHE) Report Database contains 130 reports on housing construction types in 43 seismically active countries. Each housing report is a detailed description of a housing type in a particular country. The description is prepared from a number of standard closed-ended questions and some narrative that have been provided by report authors. Each report has five major categories including architectural and structural features; Building Materials and Construction Process; Socio-economic Issues; Past Performance In Earthquakes, Seismic Features and Vulnerability; and Retrofit. All of the housing reports in this database have been contributed by volunteers. If you are interested in writing a housing report please contact the WHE Editorial Board.

About

The World Housing Encyclopedia (WHE) is a collection of resources related to housing construction practices in the seismically active areas of the world. The mission is to share experiences with different construction types and encourage the use of earthquake-resistant technologies worldwide. The technical activities of the WHE are steered by an international team of 22 professionals specializing in different aspects of seismic safety of buildings and structures. They bring relevant experience from 16 seismically active countries across the world. For more information about the World Housing Encyclopedia, visit http://www.world-housing.net/.

General Information

 

Report #:12
Building Type: Clay brick/concrete block masonry walls with concrete floors (predating seismic codes or with a few seismic features)
Country: Colombia
Author(s): Luis Gonzalo Mejia
Last Updated:
Regions Where Found: Buildings of this construction type can be found in Colombia. It represents approximately 50% of the existing housing stock of medium rise buildings (4- to 6-story high). This type of housing construction is commonly found in urban areas. Majority of buildings of this type found in rural areas are 1- and 2-story high.
Summary:

Typical multi-family housing construction found in urban areas of Colombia. ...

Length of time practiced: Less than 25 years
Still Practiced: Yes
In practice as of:
Building Occupancy: Residential, 5-9 units
Typical number of stories: 5
Terrain-Flat: Typically
Terrain-Sloped: Typically
Comments:


 

Features

 

 

Plan Shape Square, solidRectangular, solid
Additional comments on plan shape Typically, a square plan (4 flats per floor) or a rectangular plan (2 flats per floor).
Typical plan length (meters) 17
Typical plan width (meters) 17
Typical story height (meters) 2.6
Type of Structural System Masonry: Unreinforced Masonry Walls: Brick masonry in lime/cement mortarMasonry: Unreinforced Masonry Walls: Concrete block masonry in cement mortar
Additional comments on structural system The walls carry both lateral and gravity loads down to the R.C. strip foundation. In poor soil conditions, pile foundations are used because of the great susceptibility to settlement of the bearing walls. It is important to mention that the slabs span normally in one direction so the walls in one direction sustain gravity and lateral loads and the walls in the cross direction carry lateral loads only. This is a bearing wall system, wherein the walls provide stiffness for in-plane lateral loading and stability to resist lateral loads (wind and seismic effects). Floor slabs are either 100 mm thick R.C. slabs or different types of slab and joist floors; in some cases, slabs with concrete joists and tile blocks are used. The roof is normally made from rafters, sheathing roofing felt and asbestos-cement tile or R.C. slab. Floor slab can act as a rigid diaphragm; the same is not true for the wooden roof because a continuous R.C. beam (bond beam) atop the walls is often absent.
Gravity load-bearing & lateral load-resisting systems Most buildings of this construction are brick masonry in lime/cement mortar or clay brick/tile masonry, with wooden posts and beams; however, some buildings are concrete block masonry in cement mortar or clay brick masonry, with concrete posts/tie columns and beams.
Typical wall densities in direction 1 5-10%
Typical wall densities in direction 2 5-10%
Additional comments on typical wall densities The typical structural wall density is 6% to 8.5%.
Wall Openings Information about the openings in a typical median building is summarized below: Number of openings Size (sq m): Doors Windows Facade 5 0 1.80 Opening area/wall area: Between 0.5 and 1.0m from corners Position of opening: Interior 7 2.0 0. Total 30%.
Is it typical for buildings of this type to have common walls with adjacent buildings? No
Modifications of buildings There are no many modifications in this building type. The most typical modification pattern observed is demolition of interior walls.
Type of Foundation Shallow Foundation: Reinforced concrete strip footingDeep Foundation: Reinforced concrete bearing pilesDeep Foundation: Reinforced concrete skin friction piles
Additional comments on foundation It consists of reinforced concrete end-bearing piles and reinforced concrete skin-friction piles. In some Colombian cities e.g. Bogota, deep foundations are mandatory in a typical case. However, in other cities e.g. Medelin, R.C. strip footings are normally used.
Type of Floor System Cast-in-place beamless reinforced concrete floorOther floor system
Additional comments on floor system Other: Structural concrete cast-in-place flat slabs, precast solid slabs The floor is considered to be a rigid diaphragm that transfers the loads to the wall, although in many instances the floor-to-wall connections are deficient.
Type of Roof System Roof system, other
Additional comments on roof system Other: Timber wood planks or beams that support slate, metal, asbestos-cement or plastic corrugated sheets or tiles; wood planks or beams supporting natural stones slates The roof is considered to be a flexible structure.
Additional comments section 2 This type of construction is found on flat terrain (in the coastal areas) and in the continental region (the Andean) on the sloped and occasionally very steep terrain When separated from adjacent buildings, the typical distance from a neighboring building is 10 meters.

 

Building Materials and Construction Process

 

 

Description of Building Materials


Structural Element Building Material (s)Comment (s)
Wall/Frame Concrete block masonry walls Clay Brick masonry wall Cement Mortar Cement groutf'm = 10.0 MPa w/h/l 150x200x400 mm120x200x400 mm f'm = 3 - 10.0 MPa w/h/l 200 x 100 x 400200 x 150 x 400 3MPa for unreinforced or confined masonry and 10MPa for masonry with interior reinforcement f'm = 5 - 10.0 MPa Cement : Sand1:6 to 1:4 Better strengths for buildings with vertical reinforcement, because they have some seismic features. 10.0 MPa 1:4 For walls with vertical reinforcement
Foundations Reinforced concretef'c = 20.0 MPa 1 : 2 : 3 Cement/sand/aggregates
Floors R.C. slabs or hollow tile10.0 # 20.0 MPa 1:3:5 ->1:2:3 Cement/sand/aggregates
Roof Abarco (Cariniane piriformis) 9.0 MPa 50 x 100 mm Whenever the roof is in R.C. properties are the same as floors.
Other

Design Process


Who is involved with the design process? EngineerArchitectOther
Roles of those involved in the design process Whenever engineered, this construction type is built for speculation purposes.
Expertise of those involved in the design process Architects and engineers participate in the design of buildings of this type built for inhabitants belonging to the middle economic class. However, architects and engineers are not involved in the informal construction developed in areas inhabited by poorer sections of the society. If engineers and architects are involved in the construction, there is a "resident" (architect or engineer) on the site during the construction. Unfortunately, he/she is concerned mainly with the project cost aspects (rather than with the construction quality). Engineers and architects do not play any role in informal projects developed for poor people.

Construction Process


Who typically builds this construction type? Other
Roles of those involved in the building process
Expertise of those involved in building process The masons involved in the construction are usually skilled and semi-skilled.
Construction process and phasing This is a typical construction process: firstly, the terrace is formed, followed by the construction of strip foundation. Subsequently, walls, slabs and roof are built, and the masons are skilled or semi-skilled. No equipment is used except for the simple tools. Normally, buildings of this type are built by a developer (in some cases by the owner). The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size. The above statements are true, except for the case of informal construction.
Construction issues

Building Codes and Standards


Is this construction type address by codes/standards? Yes
Applicable codes or standards 1984: Colombian code for earthquake resistant buildings CCCSR-84. 1998: Colombian code for earthquake resistant design and construction of buildings NSR-98 Prior to 1984, the ACI and UBC codes were widely used.
Process for building code enforcement After an earthquake, the authorities enforce the use of building codes, however shortly thereafter these regulations are not enforced with an adequate effort.

Building Permits and Development Control Rules


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 Some of these buildings, especially those of unreinforced masonry construction or confined masonry are informal construction.

Building Maintenance and Condition


Typical problems associated with this type of construction As the amount of reinforcement is it rather limited (and in some cases does not exist at all), and the quality of materials and workmanship is generally poor, this construction type is very susceptible to earthquake effects.
Who typically maintains buildings of this type? Owner(s)
Additional comments on maintenance and building condition

Construction Economics


Unit construction cost On the average $300,000 Colombian pesos/ sq m ($US 150 /sq m)
Labor requirements It is possible to construct one floor per month on the average (when the building is designed for its final size and engineers/architects participate in the construction).
Additional comments section 3

 

Socio-Economic Issues

 

 

Patterns of occupancy Normally one family occupies one housing unit. On the average, 5 floors per building; consequently, there are 20 units in buildings of a square plan (four apartments per floor), and 10 units in buildings of a rectangular plan (two apartments per floor).
Number of inhabitants in a typical building of this construction type during the day 5-10
Number of inhabitants in a typical building of this construction type during the evening/night >20
Additional comments on number of inhabitants
Economic level of inhabitants Low-income class (poor)Middle-income class
Additional comments on economic level of inhabitants Ratio of housing unit price to annual income: 5:1 or worse The above are average values. House price for middle class section ranges from US$ 30,000 to 50,000. The approximate economic distribution of population in Colombia is as follows: Economic status % Annual Income Very poor 35 <1000 Poor 35 1000 - 2000 Middle Class 25 2000 -10000 High Middle Class 4 10000 - 40000 Rich 1 >40000 Economic Status: For Poor Class the Housing Price unit is 10000 and the Annual Income is 1500. For Middle Class the Housing Price unit is 40000 and the Annual Income is 6000.
Typical Source of Financing Combination
Additional comments on financing The main source of financing for the poor people is informal network (friends and relatives) and (sometimes) small lending institutions. For the middle class population, the main sources of financing are personal savings and commercial banks.
Type of Ownership RentOwn outrightOwn with debt (mortgage or other)Units owned individually (condominium)
Additional comments on ownership
Is earthquake insurance for this construction type typically available? Yes
What does earthquake insurance typically cover/cost Earthquake insurance is available only for engineered buildings. At the present time, premium discounts are not available for seismically strengthened buildings, however the insurance companies are dealing with this matter. Although there are many unclear aspects in this matter, in general the insurance covers the previously fixed value of the building. The insurance cost varies from 0.1 to 0.15% of the building value.
Are premium discounts or higher coverages available for seismically strengthened buildings or new buildings built to incorporate seismically resistant features? No
Additional comments on premium discounts
Additional comments section 4

 

Earthquakes

 

 

Past Earthquakes in the country which affected buildings of this type


YearEarthquake Epicenter Richter Magnitude Maximum Intensity
19794.8N, 76.2W, depth: 108 km(Mistrato)
19832.46N, 76.69W, depth: 22 km (Popayan)
347384.1N, 76.62W, depth: 73 km (Pereira)
361854.46N, 75.72W, depth: 17 km (Armenia)
6.7 MsVIII MMI (MANIZALES)
5.5 MbIX MMI (Popayan)
6.4 MwVIII MMI (PEREIRA)
6.0 MsIX MMI (ARMENIA)

Past Earthquakes


Damage patterns observed in past earthquakes for this construction type Typical earthquake damages are illustrated in Figures 7-13.
Additional comments on earthquake damage patterns

Structural and Architectural Features for Seismic Resistance


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.
Structural/Architectural Feature Statement Seismic Resistance
Lateral load pathThe structure contains a complete load path for seismic force effects from any horizontal direction that serves to transfer inertial forces from the building to the foundation.FALSE
Building Configuration-VerticalThe building is regular with regards to the elevation. (Specify in 5.4.1)TRUE
Building Configuration-HorizontalThe building is regular with regards to the plan. (Specify in 5.4.2)TRUE
Roof ConstructionThe roof diaphragm is considered to be rigid and it is expected that the roof structure will maintain its integrity, i.e. shape and form, during an earthquake of intensity expected in this area.FALSE
Floor ConstructionThe floor diaphragm(s) are considered to be rigid and it is expected that the floor structure(s) will maintain its integrity during an earthquake of intensity expected in this area.TRUE
Foundation PerformanceThere is no evidence of excessive foundation movement (e.g. settlement) that would affect the integrity or performance of the structure in an earthquake. TRUE
Wall and Frame Structures-RedundancyThe number of lines of walls or frames in each principal direction is greater than or equal to 2.TRUE
Wall ProportionsHeight-to-thickness ratio of the shear walls at each floor level is: Less than 25 (concrete walls); Less than 30 (reinforced masonry walls); Less than 13 (unreinforced masonry walls);FALSE
Foundation-Wall ConnectionVertical load-bearing elements (columns, walls) are attached to the foundations; concrete columns and walls are doweled into the foundation.TRUE
Wall-Roof ConnectionsExterior walls are anchored for out-of-plane seismic effects at each diaphragm level with metal anchors or straps. TRUE
Wall OpeningsN/A
Quality of Building MaterialsQuality of building materials is considered to be adequate per the requirements of national codes and standards (an estimate). FALSE
Quality of WorkmanshipQuality of workmanship (based on visual inspection of a few typical buildings) is considered to be good (per local construction standards).FALSE
MaintenanceBuildings of this type are generally well maintained and there are no visible signs of deterioration of building elements (concrete, steel, timber).FALSE

Additional comments on structural and architectural features for seismic resistance Foundation Performance: Occasionally, there are buildings with induced weaknesses caused by foundation movements (please see Figure 12). Wall-Roof connections: See Additional Comments in Sections 2.10 & 2.11 #Type of floor/roof system#.
Vertical irregularities typically found in this construction type Other
Horizontal irregularities typically found in this construction type Other
Seismic deficiency in walls -Unreinforced or with insufficient vertical and horizontal reinforcement. - Stepped construction (offsets) for example half of the buildings with six stories and the other half with five due to the sloping terrain (resulting in nonuniform vertical stiffne
Earthquake-resilient features in walls
Seismic deficiency in frames
Earthquake-resilient features in frame
Seismic deficiency in roof and floors #NAME?
Earthquake resilient features in roof and floors
Seismic deficiency in foundation
Earthquake-resilient features in foundation

Seismic Vulnerability Rating


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

High vulnerabilty Medium vulnerabilityLow vulnerability
ABCDEF
Seismic vulnerability class |- o -|

Additional comments section 5

Retrofit Information

 

 

Description of Seismic Strengthening Provisions


Structural Deficiency Seismic Strengthening
Walls -Unreinforced or with insufficient vertical and horizontal reinforcement. - Stepped construction (offsets) for example half of the buildings with six stories and the other half with five due to the sloping terrain (resulting in nonuniform vertical stiffness distribution). See Additional Comments
Roof and floors: - Absence of continuous boundary members, chords and collectors. -Weak roof-wall and floor-wall connections. See Additional Comments
Other : -Poor quality of workmanship and materials. -Foundations designed only for vertical loads without considerations for overturning moments. See Additional Comments

Additional comments on seismic strengthening provisions Due to the fact that this construction type in general belongs to poor or middle class population, the costs of seismic strengthening is so prohibitive and unaffordable; this is a major reason for a very limited experience in this area. For the above reason, only scarce efforts have been made in the area of seismic strengthening. As illustrated in Figures 24 and 25, an appropriate seismic strengthening technique includes the installation of new end confining members in the selected walls. An alternative seismic strengthening technique that would be appropriate for buildings of this type (using the Fiber Reinforced Polymers) is very expensive.
Has seismic strengthening described in the above table been performed? No
Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages? N/A
Was the construction inspected in the same manner as new construction? N/A
Who performed the construction: a contractor or owner/user? Was an architect or engineer involved? N/A
What has been the performance of retrofitted buildings of this type in subsequent earthquakes? N/A
Additional comments section 6

 

References

1. Normas Colombianas de y construccion Sismo Resistente (NSR-98)


Authors


Name Title Affiliation Location Email
Luis Gonzalo Mejia Consulting Structural Engineer L.G.M y Cia. Calle 49b #77b #12 Medellin Colombia lgm@epm.net.co

Reviewers


Name Title Affiliation Location Email
Sergio Alcocer Director of Research Circuito Escolar Cuidad Universitaria, Institute of Engineering, UNAM Mexico DF 4510, MEXICO salcocerm@iingen.unam.mx