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 #:27
Building Type: Confined Masonry Building with Concrete blocks, tie-columns and beams
Country: Iran
Author(s): Behrokh Hosseini Hashemi
Faramarz Alemi
Mohsen Ghafory Ashtiany
Last Updated:
Regions Where Found: Buildings of this construction type can be found in rural areas of Iran. The percentage of this housing type in those regions is almost 10%. This type of housing construction is commonly found in rural areas.
Summary:

This is a typical confined brick masonry housing construction common ...

Length of time practiced: 25-60 years
Still Practiced: Yes
In practice as of:
Building Occupancy: Single dwelling
Typical number of stories: 1
Terrain-Flat: Typically
Terrain-Sloped: Typically
Comments: These buildings are typically found in flat, sloped and hilly terrain. They do not share common walls with adjacent buildings. T


 

Features

 

 

Plan Shape Rectangular, solid
Additional comments on plan shape The typical shape of a building plan for this housing type is rectangular. To view outside the building, typically a window opening is built in external walls. These windows almost take 40% of the external walls areas. The other wall has one or two doors. The door sizes are typically 90 X 210 (cm). The overall window and door areas are about 25% of the overall wall surface area.
Typical plan length (meters) 5
Typical plan width (meters) 9
Typical story height (meters) 3
Type of Structural System Masonry: Confined Masonry: Concrete blocks, tie columns and beams
Additional comments on structural system The vertical load-resisting system is confined masonry wall system. Gravity loads sustain by bearing masonry brick walls. The lateral load-resisting system is confined masonry wall system. In both directions of the buildings lateral load-resisting system are provided by masonry brick shear walls which are confined with concrete tie column and beams.
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 up to 20 %. Total wall area/plan area (for each floor) 0.2.
Wall Openings To view outside the building, typically a window opening is built in external walls. These windows almost take 40% of the external walls areas. The other wall has one or two doors. The door sizes are typically 90 X 210 (cm). The overall window and door areas are about 25% of the overall wall surface area.
Is it typical for buildings of this type to have common walls with adjacent buildings? No
Modifications of buildings This type of construction does not have many modifications.
Type of Foundation Shallow Foundation: Reinforced concrete strip footing
Additional comments on foundation
Type of Floor System Other floor system
Additional comments on floor system The floor/ and roof are considered to be a rigid diaphragm.
Type of Roof System Roof system, other
Additional comments on roof system The floor/ and roof are considered to be a rigid diaphragm.
Additional comments section 2 The main function of this building typology is single-family house. In a typical building of this type, there are no elevators and 1-2 fire-protected exit staircases. Building of this type can have as the one main entry so the two doors. Buildings of this type in some places are located close together and in other places are scattered When separated from adjacent buildings, the typical distance from a neighboring building is 5 meters.

 

Building Materials and Construction Process

 

 

Description of Building Materials


Structural Element Building Material (s)Comment (s)
Wall/Frame Clay brick masonry. / Steel bars.Clay brick masonry: 150 Kg/sq cm 10 Kg/sq cm characteristic strength, 1:6 / 55 X 110 X 220 (mm) mix proportions/dimensions Steel bars: 3000 Kg/sq cm characteristic strength
Foundations Concrete.210 Kg/sq cm characteristic strength, 1:2:4 mix proportions
Floors Wood
Roof Wood
Other

Design Process


Who is involved with the design process? EngineerArchitect
Roles of those involved in the design process For design of building, engineers and architectures are both involved. However, during the construction process they do not spend any time to visit the site.
Expertise of those involved in the design process As far as the design concern, engineers do their job properly. But the main problem is the construction of this type of buildings in rural areas, due to lack of skilled worker.

Construction Process


Who typically builds this construction type? Other
Roles of those involved in the building process It is typically built by developers and the builders does not necessary live in this building type.
Expertise of those involved in building process The main problem is the construction of this type of buildings in rural areas, due to lack of skilled worker.
Construction process and phasing Typically developers build these types of constructions. Process starts with the foundations and then bearing walls. Process continues by adding the concrete tie columns and then tie beams then placing of wood beams and finally putting the finishing on the hole building. The construction of this type of housing takes place incrementally over time. Typically, the building is originally designed for its final constructed size.
Construction issues

Building Codes and Standards


Is this construction type address by codes/standards? Yes
Applicable codes or standards The first official issue about this type of building was in 1987. The Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard 2800) addressed this type of construction. Iranian Code of Practice for Seismic Resistant Design of Building, 1st Edition- 1987 and 2nd Edition-1999 Iranian National Building Code, Part: 8, Reinforced and unreinforced masonry buildings. The year the first code/standard addressing this type of construction issued was 1987. Iranian Code of Practice for Seismic Resistant Design of Building, 1st Edition- 1987 and 2nd Edition-1999.
Process for building code enforcement The building department of municipalities approves the design and holds the designer responsible for the projects. For those constructions, which are supported by government's fund, there is a proper control during construction. But for the others, there is not any control.

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? No
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)Renter(s)
Additional comments on maintenance and building condition

Construction Economics


Unit construction cost A unit construction may cost 500,000 Rials/sq m ( 250 $US/sq m).
Labor requirements For a typical one story building needs about 30 to 40 days to complete the load bearing structure.
Additional comments section 3

 

Socio-Economic Issues

 

 

Patterns of occupancy One family usually occupies each house.
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
Additional comments on number of inhabitants Roughly an Iranian family has 4~6 members.
Economic level of inhabitants Very low-income class (very poor)
Additional comments on economic level of inhabitants For Poor Class the Housing Price Unit is 5000 and the Annual Income is 1000. Ratio of housing unit price to annual income: 5:1 or worse
Typical Source of Financing Owner financedPersonal savingsCommercial banks/mortgages
Additional comments on financing
Type of Ownership Own outrightOwn with debt (mortgage or other)
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
1990Manjil
7.6IX

Past Earthquakes


Damage patterns observed in past earthquakes for this construction type
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.N/A
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.FALSE
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);TRUE
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. FALSE
Wall OpeningsTRUE
Quality of Building MaterialsQuality of building materials is considered to be adequate per the requirements of national codes and standards (an estimate). TRUE
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 Unequal stiffness distribution.
Earthquake-resilient features in walls
Seismic deficiency in frames Poor quality of workmanship and materials.
Earthquake-resilient features in frame
Seismic deficiency in roof and floors Lack of proper connection between roof and masonry shear walls They are not perfectly rigid diaphragm.
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
Shear wall Add new shear wall
Tie beams Increasing the size of the existing tie beams and adding new tie beams for added new walls
Roof Proper connections of the wood beams to the tie beams (existing and new construction).
New Construction Roof: Proper connections of the wood beams to the tie beams.

Additional comments on seismic strengthening provisions
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?
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 Simple Pictorial Guideline for Constructing Earthquake Resistant Adobe Building In Different Rural Areas Hosseini Hashemi,B. and Alemi,F. to be published in Farsi


Manjil-Rudbar Earthquake of June 20,90 Reconnaissance Report IIEES Publication No. 70-91-1, Tehran, Iran 1991


Iranian Code of Practice for Seismic Resistant Design of Building, 1st Edition- 1987 and 2nd Edition-1999 Building and Housing Research Center, BHRC-PN S 253, Tehran, Iran


Iranian National Building Code - Part 8: Reinforced and unreinforced masonry buildings Ministry of Housing and Urban Development, Tehran, Iran







Authors




Name Title Affiliation Location Email
Behrokh Hosseini Hashemi Assistant professor IIEES No. 27, Arghavan St., Dibaji, Farmanieh, Tehran, Iran behrokh@iiees.ac.ir
Faramarz Alemi Professor IIEES No. 27, Arghavan St., Dibaji, Farmanieh, Tehran, Iran alemi@dena.iiees.ac.ir
Mohsen Ghafory Ashtiany Professor President of IIEES No. 27, Arghavan St., Dibaji, Farmanieh, Tehran, Iran ashtiany@dena.iiees.ac.ir

Reviewers


Name Title Affiliation Location Email
Farzad Naeim Vice President John A. Martin & Associates Los Angeles CA 90015, USA farzad@johnmartin.com