Report: 59

Building Type: Reinforced concrete frame with concrete shear walls - dual system

Country: SYRIAN ARAB REPUBLIC

Author(s): Adel Awad, Hwaija Bassam, Isreb Talal

Last Updated:

Regions Where Found: Buildings of this construction type can be found in the main cities of Syria like Damascus, Aleppo, Latakia, Homs, and Hama. This type of housing construction is commonly found in urban areas.

Summary: These buildings are characterized by a combination of shear walls and frames in both directions. The buildings are multiple housing units found in the main cities of Syria. The shear walls are often part of the elevator and service cores, whereas the frames are arranged in-plane, in conjunction with the walls, to support the floor system. Stiffness and mass distribution are irregular and the majority of buildings may experience soft-story or torsional problems. As a result, these buildings are expected to have only moderate seismic resistance.

Length of time practiced: Less than 25 years

Still Practiced: Yes

In practice as of:

Building Occupancy: Residential, 20-49 units

Typical number of stories: 6-15

Terrain-Flat: Typically

Terrain-Sloped: Typically

Comments:

Plan Shape: Rectangular, solid

Additional comments on plan shape:

Typical plan length (meters): 30

Typical plan width (meters): 20

Typical story height (meters): 3.1

Type of Structural System: Structural Concrete: Moment Resisting Frame: Dual system Frame with shear wall

Additional comments on structural system: The vertical and lateral load-resisting system is a dual system. Shear walls and frames (columns, beams) carry gravity loading. We can assume that the shear walls provide adequate strength and stiffness to control lateral displacements.

Gravity load-bearing & lateral load-resisting systems:

Typical wall densities in direction 1: 3-4%

Typical wall densities in direction 2: 3-4%

Additional comments on typical wall densities: The typical structural wall density is up to 3 %. The ratio between total wall area/plan area is 1 to 3% (for each floor).

Wall Openings: Area of openings/walls surface area= 20% for inner walls and 40% for outer walls.

Is it typical for buildings of this type to have common walls with adjacent buildings?: No

Modifications of buildings: Buildings of this type haven't a lot of modifications yet.

Type of Foundation: Shallow Foundation: Reinforced concrete isolated footingShallow Foundation: Reinforced concrete strip footingShallow Foundation: Mat foundation

Additional comments on foundation:

Type of Floor System: Other floor system

Additional comments on floor system: waffle slabs (cast-in-place), solid slabs (precast)

Type of Roof System: Roof system, other

Additional comments on roof system: waffle slabs (cast-in-place), solid slabs (precast)

Additional comments section 2: When separated from adjacent buildings, the typical distance from a neighboring building is 10 meters.

Who is involved with the design process: EngineerArchitect

Roles of those involved in the design process: The designer may visit the construction site, at request.

Expertise of those involved in the design process: The structural engineer will have 5 years of studies and more than 5-10 years of experience.

Who typically builds this construction type? Other

Roles of those involved in the building process: It is built by developers and sold to the people who may live in this construction type.

Expertise of those involved in building process: The construction engineer may have 5 years of studies and less experience than the structure engineer.

Construction process and phasing: The owner of the land will hire an architectural office and structural engineer to design the building. They will use modern equipment. 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:

Is this construction type address by codes/standards? Yes

Applicable codes or standards: Starting from 1997, the seismic design for buildings is mandatory as a law: Syrian Code for Earthquake Resistant Building (1995). Prior to 1997, seismic design was not applicable but the normal Syrian Building Code is used from 1972. The year the first code/standard addressing this type of construction issued was 1972. The most recent code/standard addressing this construction type issued was 1997.

Process for building code enforcement: The building design must follow the Syrian Code 1995. In case of damage arbitration process may take place at the court of justice. There is compulsory inspection during the construction and good revision of the structural project.

: 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:

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:

Unit construction cost: A unit construction may cost 170-300 USD/m# (USD =50 Syrian pound (SP), on market rate).

Labor requirements: One floor per month.

Additional comments section 3:

Patterns of occupancy: Each building typically has 21-50 housing unit(s). 45 units in each building. One family typically occupies one unit.

Number of inhabitants in a typical building of this construction type during the day: >20

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: Middle-income classHigh-income class (rich)

Additional comments on economic level of inhabitants: Ratio of housing unit price to annual income: 4:1 Notes: 1. Below are the general guidelines related to the economic status of the inhabitants: Very Poor = lowest 10% of the population (per GDP) Poor = lowest 30% of the population Middle Class = from the lowest 30% up to the top 20% of the population Rich = top 20% of the population. Additional comments: GNP per capita, in 1997, was $1120. GDP per capita, in 1996, was $1288. Economic Level: For Middle Class the Housing Unit Price is 25000 and the Annual Income is 6000. For Rich Class the Housing Unit Price is 40000 and the Annual Income is 15000.

Typical Source of Financing: Owner financedPersonal savingsCommercial banks/mortgages

Additional comments on financing:

Type of Ownership: RentOwn outrightOwn with debt (mortgage or other)Long-term leaseOther

Additional comments on ownership: Other: Ownership by heritage.

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:

—-

Damage patterns observed in past earthquakes for this construction type: Data about earthquakes taken from (Ambraseys, 1983), starting from 18th Century up to date. But estimation of values (Magnitude M and Maximum Intensity MMI) were made by us depending on our findings and experience. Most of the building destroyed were of adobe and stone masonry particularly in urban regions.

Additional comments on earthquake damage patterns:

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.

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: No flexural tension reinforcement; and no confinement at the wall ends.

Earthquake-resilient features in walls:

Seismic deficiency in frames: No special transverse reinforcement at the critical region (joints).

Earthquake-resilient features in frame:

Seismic deficiency in roof and floors: Weak connection between roof, floors and walls; and no lintel beams.

Earthquake resilient features in roof and floors:

Seismic deficiency in foundation:

Earthquake-resilient features in foundation:

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

Additional comments section 5:

—-

Additional comments on seismic strengthening provisions: Seismic strengthening has not been done in Syria so far.

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:

• Statistical Abstract 1999 Central Bureau of Statistic, Damascus 1999

• Earthquake Damage in the Arabic Region Ambraseys,N,N. Assessment and Mitigation, UNESCO publication , pp. 11-15 1993

• Scientific Fundamentals for Assessment and Mitigation of Earthquake Risk in Syria Awad,A. Damascus University Journal (“Issues of Applied Research”) Vol. 9, No 33-34, pp.21-47 1993

• Human Development Report 1999 United Nation Development Program (UNDP) Oxford University Press, NY 1999

• Seismic Design of Reinforced Concrete and Masonry Buildings Paulay,T. and Priestley,M.J.N. John Wiley and Sons 1992

• Syrian Code for Earthquake Resistant Design and Construction of Building Syrian Engineers Order, Damascus Damascus 1995

• European Marcoseismic Scale 1998 (EMS98) Gruenthal,G. European Seismological Commission (ESC), Luxembourg 1998