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 #:114
Building Type: Stonework building with wooden timber roof
Country: Iran
Author(s): Masoud N. Ahari
Alireza Azarbakht
Last Updated:
Regions Where Found: Buildings of this construction type can be found in most villages in the mountain regions of Alborz and Zagros (Figure 7). This type of housing construction is commonly found in rural areas. This kind of building is not practiced in major cities but only in rural cities and mountainous villages. The major reason for the popularity of this form of construction is that in mountainous regions, stone mines are easily accessible. Two kind of stones are used in these stonework buildings: 1-Rubble stone, a by-product of the mining industry (Figure 15). 2-Carcass stone, which comes from riverbeds (Figure 14).
Summary:

Stonework buildings are a common type of rural construction in ...

Length of time practiced: More than 200 years
Still Practiced: Yes
In practice as of:
Building Occupancy: Single dwelling
Typical number of stories: 1-2
Terrain-Flat: Typically
Terrain-Sloped: Typically
Comments: Usually this kind of building is used for living but sometimes when the building is located at the foot of a slope, the ground s


 

Features

 

 

Plan Shape Other
Additional comments on plan shape A typical plan of this kind of building is shown in figure 3.
Typical plan length (meters)
Typical plan width (meters)
Typical story height (meters) 2.5-3
Type of Structural System Masonry: Stone Masonry Walls: Rubble stone (field stone) in mud/lime mortar or without mortar (usually with timber roof)
Additional comments on structural system The vertical load-resisting system is confined masonry wall system. The roof of the building is constructed with joists spaced at 20-50 centimeters which transfer loads from the roof to the walls (500-600 kilogram per square meter) and then walls transfer loads to the ground directly. Wall thickness is between 45-70 centimeters. These walls have no foundations. The lateral load-resisting system is confined masonry wall system. Walls carry the inertia forces produced by the roof mass. These loads must be transferred from the walls to the ground by in-plane behavior of the walls, but usually there is no proper path for adequately transferring these seismic loads to the ground in stonework buildings. Floors and roofs do not work as rigid diaphragms and there is rarely connection between the roof components (joists and secondary joists). Heavy floors and roofs are supported on walls without any connection (Figure 24). These deficiencies may cause separation and collapse of roof components as shown in Figures 30, 31 and 32. 1- Walls collapse under out of plane loads. 2- Improper arrangement of stone units may cause buckling of outer stones in walls (Figures 18, 21 and 26). 3- Walls collapse because of poor shear capacity of mortar; also there is not enough cohesion between stone units and mud mortar.
Gravity load-bearing & lateral load-resisting systems
Typical wall densities in direction 1 >20%
Typical wall densities in direction 2 >20%
Additional comments on typical wall densities The typical structural wall density is none.
Wall Openings Most windows are about 120X120 centimeters and doors are 200X100 centimeters.
Is it typical for buildings of this type to have common walls with adjacent buildings? Yes
Modifications of buildings Usually there is no modification.
Type of Foundation Shallow Foundation: Wall or column embedded in soil, without footing
Additional comments on foundation
Type of Floor System Other floor system
Additional comments on floor system
Type of Roof System Roof system, other
Additional comments on roof system The roof includes wooden joists and a set of secondary joists which are plastered with a thick layer of mud (Figures 24, 25 and 5).
Additional comments section 2 Usually they are constructed side by side and there is no distance between them.

 

Building Materials and Construction Process

 

 

Description of Building Materials


Structural Element Building Material (s)Comment (s)
Wall/Frame (wall) Stone; No frame.
Foundations No foundation.
Floors Joists with mud mortar and straw
Roof Joists with mud mortar and straw
Other

Design Process


Who is involved with the design process? Other
Roles of those involved in the design process Engineers or architects are not present in the design/construction of this housing type.
Expertise of those involved in the design process

Construction Process


Who typically builds this construction type? Builder
Roles of those involved in the building process The builder lives in this construction type.
Expertise of those involved in building process This kind of building is constructed by people lacking formal construction expertise. Sometimes expert bricklayers build these buildings with some special architectural features in the walls and roof but they are not certified.
Construction process and phasing First, the ground is excavated with a width of 80-100 centimeters and a depth of 50-100 centimeters for the wall perimeter. Next, the walls are constructed from bottom of this cavity. On rare occasions, a wooden column is used at the intersection of stone walls. Wooden beams are then placed on top of walls at a 20-50 centimeter spacing distance. The top surface of the beams is covered with thinner wooden beams or board(plank). Finally the roof is plastered with mud in two separate stages to achieve a total thickness of 20-30 centimeters. 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. There is no special design & drawings for this kind of construction.
Construction issues

Building Codes and Standards


Is this construction type address by codes/standards? No
Applicable codes or standards
Process for building code enforcement

Building Permits and Development Control Rules


Are building permits required? Yes
Is this typically informal construction? Yes
Is this construction typically authorized as per development control rules? No
Additional comments on building permits and development control rules These buildings are old. Building permits are required to build this housing type.

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 per m2 of built-up area expressed using a currency used in the region, and, if possible, an equivalent amount in $US in the brackets e.g. 200 Rs/m2 (5 $US/m2).
Labor requirements
Additional comments section 3

 

Socio-Economic Issues

 

 

Patterns of occupancy Typically there is one family per housing unit that may sometimes include grandparents.
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 Very low-income class (very poor)Low-income class (poor)
Additional comments on economic level of inhabitants Ratio of housing unit price to annual income: 1:1 or better
Typical Source of Financing Owner financed
Additional comments on financing Because this kind of building is placed in mountainous areas, the owners of them are usually peasants or shepherd.
Type of Ownership RentOwn outright
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
1985Ardabil
1990Manjil
1992Lordekan
2004Firoozabad
5.8VII
7.6
5VII
6.3

Past Earthquakes


Damage patterns observed in past earthquakes for this construction type
Additional comments on earthquake damage patterns During earthquakes in the mountainous regions of Iran, there is extensive damage and many casualties in these buildings due to wall collapses. Figures 26 through 24 show typical damage of stone walls from earthquakes. After wall failure, the heavy roof generally collapses. Figures 30, 31 and 32 show evidence of this phenomenon.

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)FALSE
Building Configuration-HorizontalThe building is regular with regards to the plan. (Specify in 5.4.2)FALSE
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.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. FALSE
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.FALSE
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). 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 The roof consists of a mud-straw mix about 20-30 centimeters thick, which makes the roof very heavy. The walls are not connected together or to the roof with adequate connections. There are no tie beams or columns in these buildings. The walls do not have enough strength to resist out-of-plane forces. The mortar also has inadequate strength. Usually these buildings are placed on steep slopes in mountainous areas which have a high potential for landslides.
Vertical irregularities typically found in this construction type Other
Horizontal irregularities typically found in this construction type Other
Seismic deficiency in walls The combination of stone and mortar has low tensile and shear strength, especially for out-of-plane seismic effects. Sometimes openings such as walls and windows reduce the strength of the bearing walls. The perimeter walls are not sufficiently connected at the corners, and behave as separate elements, which causes damage in the wall corner connections.
Earthquake-resilient features in walls
Seismic deficiency in frames No Frame exists.
Earthquake-resilient features in frame
Seismic deficiency in roof and floors Usually they consist of heavy materials that behave as flexible diaphragms in earthquakes, which undermines the connections between the stone walls and the diaphragm. Also there is not a tie beam for integrity.
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 Total collapse of this kind of building occurred during several past earthquakes in Iran. Figure 33 shows one of these catastrophes.

Retrofit Information

 

 

Description of Seismic Strengthening Provisions


Structural Deficiency Seismic Strengthening

Additional comments on seismic strengthening provisions
Has seismic strengthening described in the above table been performed?
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

Stone Walls (Report in Persian) Iranian Management and Planning Organization 1376


Retrofitting of Stone Houses in Marathwada Area of Maharashtra Arya,A.S. University of Roorkee, March 1994


Firoozabad-e-Kojour earthquake reconnaissance report Eshghi,S. and Zare,M. International Institute of Earthquake Engineering and Seismology, 1383 (In prepartion)


Lordekan earthquake report Chahar Mahal va Bakhtiary and F. Nateghi Elahi International Institute of Earthquake Engineering and Seismology, 1370


Manjil earthquake report Roodbar,S.E. International Institute of Earthquake Engineering and Seismology, 1369


Golestan-Ardebil earthquake report Ashtiani,M.G. International Institute of Earthquake Engineering and Seismology, 1377


Building and housing types of Zanjan according to architects and materials Bonyade maskane enghelabe eslami, 1372


Building and housing types of Gilan according to architects and materials Bonyade maskane enghelabe eslami, 1372


A simple pictorial guideline for resistance construction of rural houses against earthquake (Report in Persian) Hosseini,B., Alemi,F. and Khaki,A. International Institute of Earthquake Engineering and Seismology 2005


Maps referred to "Geology Survey of Iran"


Seminars, Conferences, Personal communications and practical involvements


Authors



Name Title Affiliation Location Email
Masoud N. Ahari PhD student IIEES No. 20 Sabzali Allay Taslihat Square Shahid Madani Ave., Tehran , IRAN noorali@iiees.ac.ir
Alireza Azarbakht PhD student IIEES No 370 Alvand 4 St. Arash St. Shahrake Gandarmery, Tehran , IRAN alireza_azarbakht@yahoo.com

Reviewers


Name Title Affiliation Location Email
Svetlana N. Brzev Instructor Civil and Structural Engineering Technology, British Columbia Institute of Technology Burnaby BC V5G 3H2, CANADA sbrzev@bcit.ca