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 #:16
Building Type: Loadbearing stone masonry building
Country: Greece
Author(s): T. P. Tassios
Kostas Syrmakezis

Last Updated:
Regions Where Found: Buildings of this construction type can be found in historical cities of Greece. Perhaps 10% of housing stock in the region. This type of housing construction is commonly found in both rural and urban areas.
Summary:

These buildings are mainly found in the historical centers of ...

Length of time practiced: More than 200 years
Still Practiced: Yes
In practice as of:
Building Occupancy: Single dwelling
Typical number of stories: 2-3
Terrain-Flat: Typically
Terrain-Sloped: Typically
Comments: Currently, this type of construction is being built. Only in historic districts, however. The main function of this building ty


 

Features

 

 

Plan Shape Rectangular, solid
Additional comments on plan shape
Typical plan length (meters) 10
Typical plan width (meters) 15
Typical story height (meters) 41702
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 timber frame load-bearing wall system. - Load bearing walls - Timber or metal strengthening elements. The lateral load-resisting system is unreinforced masonry walls. The main lateral load-resisting system consists of unreinforced stone masonry bearing walls. Floors and roof are wood structures. The wall layout in plan is critical for the lateral performance of this construction type. Also, the wall connections and roof/floor-to-wall connections are the critical elements of the lateral load resistance. The materials and type of construction are the most important factors affecting the seismic performance of these buildings.
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 more than 20 %. Total wall area/plan area (for each floor) 30-40%.
Wall Openings The building has eleven openings per floor, of an average size of 3.5 sq m each. The estimated opening area to the total wall surface is 18%. This is relevant to the resistance of this type of building.
Is it typical for buildings of this type to have common walls with adjacent buildings? No
Modifications of buildings Usually demolition of interior load bearing walls, or partial demolition for the insertion of an opening.
Type of Foundation Shallow Foundation: Rubble stone, fieldstone strip footing
Additional comments on foundation Masonry footings (footing width by 300 mm greater as compared to the walls).
Type of Floor System Other floor system
Additional comments on floor system Wood planks or beams with ballast and concrete or plaster finishing; The floors and roofs are considered to be rather flexible.
Type of Roof System Roof system, other
Additional comments on roof system The floors and roofs are considered to be rather flexible.
Additional comments section 2 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 Rubble stone Mortar Stone: Compressive strength= 80 MPa Mortar: Tensile strength= 0.1 to 0.2 MPa lime/sand mortar
Foundations Rubble stone Mortar Stone: Compressive strength= 80 MPa Mortar: Tensile strength= 0.1 to 0.2 MPa lime/sand mortar
Floors timber
Roof timber
Other

Design Process


Who is involved with the design process? Other
Roles of those involved in the design process
Expertise of those involved in the design process Engineers and architects play an important role during the repair and strengthening of this type of structures.

Construction Process


Who typically builds this construction type? MasonBuilder
Roles of those involved in the building process The builders (usually traditional artisans) live in this construction type.
Expertise of those involved in building process Experience of traditional builders.
Construction process and phasing Traditional builders. Stones from the area and mortar made in situ. The construction of this type of housing takes place in a single phase. 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? No
Applicable codes or standards Experience. European Codes.
Process for building code enforcement

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? No
Additional comments on building permits and development control rules This type of structure was constructed without any explicit design requirements. Building permits are not 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 Since this is a construction method that is no longer practiced, values for unit construction costs are not available.
Labor requirements Information not available.
Additional comments section 3

 

Socio-Economic Issues

 

 

Patterns of occupancy One or two families per housing unit. Usually there are 1-2 units in each building.
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 Middle-income classHigh-income class (rich)
Additional comments on economic level of inhabitants It is primarily the wealthy who can afford to live in these buildings, when they are used for housing. Ratio of housing unit price to annual income: 1:1 or better
Typical Source of Financing Owner financed
Additional comments on financing
Type of Ownership Own 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
1996Aegion
1999Athens
6.1MSK
5.9IX (MSK)

Past Earthquakes


Damage patterns observed in past earthquakes for this construction type On September 7, 1999, at 14:56 local time, a strong earthquake occurred 18 kilometres northwest of the center of Athens. The earthquake was magnitude .s =5.9 and the coordinates of the epicentre were located at 38.12.-23.64., in the area of Parnitha mountain. This earthquake came as a surprise, since no seismic activity was recorded in this region for the last 200 years. According to strong-motion recordings, the range of significant frequencies is approximately 1.5-10 Hz, while the range of the horizontal peak ground accelerations were between 0.04 to 0.36g. The most heavily damaged areas lie within a 15 km radius from the epicentre. The consequences of the earthquake were significant: 143 people died and more than 700 were injured. The structural damage was also significant, since 2,700 buildings were destroyed or were damaged beyond the repair and another 35,000 buildings experienced repairable damage. According to the EERI Reconnaissance report (see References), in the meizoseismal area, most stone masonry structures with undressed stones, constructed in the first half of the century, suffered significant damage. This included partial collapse of external walls, collapse of corners, separation of the two walls converging at a corner, and extensive cracking.
Additional comments on earthquake damage patterns Wall: Stone masonry walls were damaged in the 1999 Athens earthquake. The damage included partial collapse of external walls, collapse of corners, separation of the two walls converging at a corner, and extensive cracking (Source: EERI) Roof/floors: Extensive masonry cracking, due to low tensile and shear strength and unsatisfactory diaphragm action of the horizontal members.

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.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). 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 Rubble stone and lime mortar. The system has low tensile and shear strength, especially for out-of-plane seismic effects. Presence of large openings reduces the strength of the bearing walls.
Earthquake-resilient features in walls
Seismic deficiency in frames
Earthquake-resilient features in frame
Seismic deficiency in roof and floors Usually they consist of wooden elements, thus diaphragm behaviour and good connections with masonry walls cannot be ensured.
Earthquake resilient features in roof and floors Even for steel and timber floors/roof the presence of stiffness leads to a rigid diaphragm which is highly desired.
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
Roofs/floors - Strengthening of wall-floor connections; - Strengthening of diaphragms;
Stone masonry walls - Crack repair (see Figure 9); - Installation of RC belts or ties; - Deep repointing and installation of RC jackets (see Figure 11); - Strengthening of wall intersections (see Figure 10)

Additional comments on seismic strengthening provisions The frist step in the seismic strengthening is the deep repointing of the wall. This technique improves the tensile strength of the wall (up to 10 times). Subsequently, cement-mortar injections are applied (if required) for the further improvement - homogenization of the wall. Finally, RC jacket is applied on the wall surface (Figure 10). The overall structural resistance is greatly improved since the reinforcement (provided in concrete jacket) is activated at the critical cracking point.
Has seismic strengthening described in the above table been performed? Yes, to a great extent.
Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages? Repair following the earthquake damage.
Was the construction inspected in the same manner as new construction? Yes
Who performed the construction: a contractor or owner/user? Was an architect or engineer involved? The construction is usually performed by a contractor, not always with the involvement - supervision of an architect and/or a civil engineer.
What has been the performance of retrofitted buildings of this type in subsequent earthquakes? The performance was satisfactory.
Additional comments section 6

 

References

ITSAK. Report on the 1999 Athens Earthquake, Institute of Engineering Seismology and Earthquake Engineering, Thessaloniki, Greece (www.itsak.gr)


EERI. Special Earthquake Report: The Athens, Greece Earthquake of September 7, 1999 (www.eeri.org/earthquakes/Reconn/Greece1099/Greece1099.html)


Authors




Name Title Affiliation Location Email
T. P. Tassios Professor National Technical University of Athens 9 Iroon Polytehniou, Zographou, Athens tassiost@central.ntua.gr
Kostas Syrmakezis Professor National Technical University of Athens 9 Iroon Polytehniou, Zographou, Athens isaarsyr@central.ntua.gr

Reviewers


Name Title Affiliation Location Email
Craig D. Comartin President C.D. Comartin Associates Stockton CA 95207-1705, USA ccomartin@comartin.net