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 #:112
Building Type: Unreinforced brick masonry residential building
Country: Pakistan
Author(s): Qaisar Ali
Last Updated:
Regions Where Found: Buildings of this construction type can be found in all major cities of Pakistan except Karachi. 90% of residential buildings and 80% of all building stock consist of this type. Other types of buildings in urban areas include RC frame structures with concrete blocks or brick infill walls. In Karachi, the most populous city of Pakistan, with more than 10 million people, RC frame structures with infill walls of concrete blocks are most commonly used. Unreinforced brick masonry construction in Pakistan may constitute more than 50% of all buildings. In rural areas, unreinforced buildings in clay mortar and adobe construction were very common in the past and still exist in some areas, but now are being replaced by unreinforced brick masonry with cement sand mortar. In hilly areas, unreinforced stone masonry without mortar or with cement sand mortar are widely used. Those with financial resources opt for RC frame structures with stone infill or concrete block walls. This type of housing construction is commonly found in urban areas. Most often found in urban areas but sometimes in rural areas, where adobe houses can also be found.
Summary:

In Peshawar and adjoining areas (in northern Pakistan), the most ...

Length of time practiced: 25-60 years
Still Practiced: Yes
In practice as of:
Building Occupancy: Single dwelling
Typical number of stories: 1-3
Terrain-Flat: Typically
Terrain-Sloped: Off
Comments: Normally used as a single-family house but sometimes also used as multiple-housing units and mixed-use.


 

Features

 

 

Plan Shape Rectangular, solid
Additional comments on plan shape
Typical plan length (meters) 10-40
Typical plan width (meters) 5-20
Typical story height (meters) 3
Type of Structural System Masonry: Unreinforced Masonry Walls: Brick masonry in lime/cement mortar
Additional comments on structural system The vertical load-resisting system is un-reinforced masonry walls. The masonry walls also act as load-bearing walls. The roof slab rests directly on walls and transfers the load to walls, which, in turn, transfer it to the foundation. The lateral load-resisting system is un-reinforced masonry walls. The lateral load-resisting system consists only of masonry walls.
Gravity load-bearing & lateral load-resisting systems
Typical wall densities in direction 1 15-20%
Typical wall densities in direction 2 15-20%
Additional comments on typical wall densities The typical structural wall density is more than 20 %. 15-30 The wall density ranges from 0.15 to 0.30 meters.
Wall Openings The houses typically have one door and one or two window openings in each wall. The openings are frequently close to the corners of rooms (< 0.3 m). The windows are generally 1.2 to 1.8 square meters and the doors are 2.2 to 2.5 square meters. The total length of the opening is 20-30% of the wall length. RCC lintel beams are commonly provided above the openings.
Is it typical for buildings of this type to have common walls with adjacent buildings? No
Modifications of buildings Building modification is not as common in urban areas but may occur in rural areas. A typical modification is the construction of additional rooms, both horizontally and vertically.
Type of Foundation Shallow Foundation: Reinforced concrete strip footing
Additional comments on foundation The foundation consists of plain cement concrete strip footing and several brick steps. The size of the foundation is normally 0.76 m. The thickness of the concrete strip is 150 mm.
Type of Floor System Cast-in-place beamless reinforced concrete floor
Additional comments on floor system
Type of Roof System Cast-in-place beamless reinforced concrete roof
Additional comments on roof system
Additional comments section 2 For small residential units (100 square meters), there is usually no separation distance; for larger units (280 to 900 square meters), there is separation in the range of 3 to 10 meters.

 

Building Materials and Construction Process

 

 

Description of Building Materials


Structural Element Building Material (s)Comment (s)
Wall/Frame Bricks and cement sand mortar.Masonry compression strength varies from 2 to 5 Mpa. 1:8 cement sand or 1:4: 4 cement, sand and stone dust Brick size: 230 mm x 115 mm x 65 mm.
Foundations Concrete10 to 18 Mpa, compressive strength. Steel yield strength is 280 Mpa. 1:2:4
Floors Concrete10 to 18 Mpa, compressive strength. Steel yield strength is 280 Mpa. 1:2:4
Roof Concrete10 to 18 Mpa, compressive strength. Steel yield strength is 280 Mpa. 1:2:4
Other

Design Process


Who is involved with the design process? ArchitectOther
Roles of those involved in the design process Almost no role for the engineer. There is, however, some involvement of architects in urban areas.
Expertise of those involved in the design process Only rule of thumb. No engineering knowledge or involvement of engineers.

Construction Process


Who typically builds this construction type? MasonContractorOther
Roles of those involved in the building process
Expertise of those involved in building process Only rule of thumb. No engineering knowledge or involvement of engineers.
Construction process and phasing The construction is typically carried out by a contractor, who arranges for masons and laborers to carry out the work. The foundations are constructed from 1:2:4 concrete. The walls are constructed from brick masonry in cement sand or cement sandstone dust mortars. RCC roof slab is laid directly on the walls. The concrete mixing is either carried out manually or through machine-operated mixers. Both the mortars and concrete are prepared with very high water-tocement ratios and are used quite often for several hours after the addition of water. The construction of this type of housing takes place in a single phase. Typically, the building is originally not designed for its final constructed size.
Construction issues

Building Codes and Standards


Is this construction type address by codes/standards? No
Applicable codes or standards Currently Pakistan does not have any building code which covers construction of such type of buildings.
Process for building code enforcement No such practice is ever carried out.

Building Permits and Development Control Rules


Are building permits required? No
Is this typically informal construction? Yes
Is this construction typically authorized as per development control rules? Yes
Additional comments on building permits and development control rules

Building Maintenance and Condition


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

Construction Economics


Unit construction cost USD 180 to 200 per square meter.
Labor requirements 10-15 persons working 8 hours a day can complete an approximately 280-squaremeter building in four months.
Additional comments section 3

 

Socio-Economic Issues

 

 

Patterns of occupancy In urban areas one family normally occupies the buildings, but in some cases there may be two or even three families residing in one building. In rural areas the house is typically occupied by one family, with the number of inhabitants frequently exceeding six.
Number of inhabitants in a typical building of this construction type during the day <5
Number of inhabitants in a typical building of this construction type during the evening/night 5-10
Additional comments on number of inhabitants
Economic level of inhabitants Low-income class (poor)Middle-income classHigh-income class (rich)
Additional comments on economic level of inhabitants
Typical Source of Financing Owner financedPersonal savingsInformal network: friends or relativesCommercial banks/mortgagesGovernment-owned housing
Additional comments on financing
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? No
What does earthquake insurance typically cover/cost
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
1994Hindu Kush
2002Hindu Kush
2005Kashmir
6.5V
6.3V
7.6VI-VIII

Past Earthquakes


Damage patterns observed in past earthquakes for this construction type Many far field earthquakes originating from the Hindu Kush region, varying from 6 to 7.5 and even up to 8 in some cases, have hit the northern part of Pakistan. The distance from the epicenter to Peshawar is in the range of 250 kilometers. Some low-level seismic activity also occurs near the city. According to MSK, Peshawar may be placed in VI or at most in VII, Islamabad in VI, and Lahore in V. A major earthquake in October, 2005, killed over 85,000 people and collapsed many buildings throughout Kashmir and NWFP. See photos for typical unreinforced masonry damage.
Additional comments on earthquake damage patterns Mainly, diagonal shear cracks. Separation of roof slab from walls.

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.TRUE
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.TRUE
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.FALSE
Wall-Roof ConnectionsExterior walls are anchored for out-of-plane seismic effects at each diaphragm level with metal anchors or straps. FALSE
Wall OpeningsFALSE
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
Vertical irregularities typically found in this construction type Other
Horizontal irregularities typically found in this construction type Other
Seismic deficiency in walls Inadequate materials used. Poor quality of mortar, excessively thick bedding joints. Poor quality of construction.
Earthquake-resilient features in walls
Seismic deficiency in frames
Earthquake-resilient features in frame
Seismic deficiency in roof and floors
Earthquake resilient features in roof and floors The RC roof helps to integrate the walls, and the structure essentially acts like a box-type structure.
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

Additional comments on seismic strengthening provisions In the past 25 years there have been several earthquakes striking various cities of Pakistan. However, there is no documentation of the damage, especially to this type of structure. Therefore, no record of earthquake damage to such buildings is currently available. Neither are there records of retrofitting or strengthening. Major deficiencies of such buildings include low-quality mortar and lack of integrity (box-type action).
Has seismic strengthening described in the above table been performed? No strengthening has been observed after earthquakes.
Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages?
Was the construction inspected in the same manner as new construction?
Who performed the construction: a contractor or owner/user? Was an architect or engineer involved?
What has been the performance of retrofitted buildings of this type in subsequent earthquakes?
Additional comments section 6

 

References

A critical review of the seismic risk zoning Ali,Q. and Naeem,A. World Conference on Earthquake Engineering, Vancouver, BC, Canada, Paper #50 2004


Seismic performance study of brick masonry buildin Ali,Q. Doctoral Thesis, Civil Engineering Department, University of Engineering and Technology, Peshaw ar 2004


Authors


Name Title Affiliation Location Email
Qaisar Ali Associate Professor Department of Civil Engineering, NWFP University of Engineering and Technology Pesh Peshaw ar 25000, PAKISTAN engrqaisarali@yahoo.com

Reviewers


Name Title Affiliation Location Email
Robin Spence Director Cambridge Architectural Research Ltd. Cambridge CB1 1DP, UNITED KINGDOM rspence@carltd.com