Report #: 50

Report Date:

Country: PERU

Housing Type:

Housing Sub-Type:

Author(s): Cesar Loaiza, Marcial Blondet

Last Updated:

Regions Where Found: Buildings of this construction type can be found in all parts of Peru, particularly in the coastal region. This type of housing construction is commonly found in urban areas.

Summary: This multifamily housing construction type has been the most commonly used in the urban areas of Peru during the last 35 years. Confined masonry buildings consist of load-bearing unreinforced clay masonry walls confined by cast-in-place reinforced concrete tie columns and beams. Tie columns are cast after the construction of the masonry walls is complete and theyare connected to the tie beams. Confined masonry walls have limited shear strength and ductility; however, buildings of this type typically have a good seismic resistance.

Length of time practiced: 25-60 years

Still Practiced: Yes

In practice as of:

Building Occupancy: Mixed residential/commercial

Typical number of stories: 4-6

Terrain-Flat: Typically

Terrain-Sloped: 3

Comments:

Average 6 units in each building; usually there are from 4 to 8 units in each building.

Plan Shape: Rectangular, solid

Additional comments on plan shape:

Typical plan length (meters): 20

Typical plan width (meters): 12

Typical story height (meters): 2.7

Type of Structural System: Masonry: Confined Masonry: Concrete blocks, tie columns and beams

Additional comments on structural system: Lateral-load resisting system: The lateral load-resisting system is confined masonry wall system. Confined masonry walls give stiffness to the structure and control lateral drift. Tie columns and post beams prevent damage due to out-of-plane bending effects and improve wall ductility. Tie columns have the longitudinal reinforcement necessary to resist overturning moments. In some cases, reinforced concrete walls are required to avoid cracking of reinforced concrete elements. Gravity load-bearing system: Generally, the same system as described above. Floor and roof structures are composite structures, made of masonry units and concrete joists that transfer the gravity loads to the walls.

Gravity load-bearing & lateral load-resisting systems:

Typical wall densities in direction 1: 4-5%

Typical wall densities in direction 2: 4-5%

Additional comments on typical wall densities: The typical structural wall density is up to 5 %. Total wall area/plan area (for each floor) is 3-5%.

Wall Openings: A typical building has 3 to 4 windows (typically 1 to 2 m wide) in each in the longitudinal direction. In the transverse direction there may be one or two openings per facade.

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

Modifications of buildings: In some cases owners build additional interior walls as a part of the building extension (new rooms or bathrooms).

Type of Foundation: Shallow Foundation: Reinforced concrete strip footing

Additional comments on foundation: Usually the foundation is of plain (unreinforced) concrete unless the soil is clay or silt

Type of Floor System: Other floor system

Additional comments on floor system: Composite masonry and concrete joist; in the analysis, the floors are considered to be rigid diaphragms.

Type of Roof System: Roof system, other

Additional comments on roof system: Composite masonry and concrete joist.

Additional comments section 2: When separated from adjacent buildings, the typical distance from a neighboring building is 0.5-1.0 meters.

Average plan area is 260 m.sq. Length varies from 15 to 30 m, and the width varies from 5 to 15 m. Story height varies from 2.5 meters to 2.8 meters.

Who is involved with the design process?: EngineerArchitect

Roles of those involved in the design process: Engineers are in charge of the structural design and construction process. Architects are in charge of the architectural design and in some cases in charge of the construction process.

Expertise of those involved in the design process: Both the structural and the construction engineer should have 5 years of study and minimum work experience of 2 years.

Who typically builds this construction type?: Other

Roles of those involved in the building process: Construction companies build the buildings of this type and sell them.

Expertise of those involved in building process: Both the structural and the construction engineer should have 5 years of study and minimum work experience of 2 years. Commonly, the construction process is inspected. The designer may visit the construction process once or twice during the construction.

Construction process and phasing: Masonry walls are built with serrated endings, then tie columns are cast against them. After that tie beams, lintels and floors are built simultaneously. The equipment commonly used is: concrete mixer, traveling crane, winch, trucks.

Typically not built incrementally, buildings originally designed for final constructed size.

Construction issues

Is this construction type address by codes/standards?: Yes

Applicable codes or standards: Seismic Design Standards E-030 (1977) National Construction Standards, Masonry Standards E-070 (1998) The most recent code/standard addressing this construction type issued was 1998.

Process for building code enforcement: Municipal authorities approve the structural and architectural design for the building. It is common that the owner hires a private inspector to supervise the construction process.

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?: BuilderOwner(s)Renter(s)

Additional comments on maintenance and building condition:

Unit construction cost: Unit construction cost may vary from 200 to 300 US$/sq m.

Labor requirements: Depending on the technology used, the construction of a typical building may take 2-3 stories per month.

Additional comments section 3:

Damage patterns observed in past earthquakes for this construction type: Wall shear cracking that propagates through tie columns.

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.

Vertical irregularities typically found in this construction type: Other

Horizontal irregularities typically found in this construction type: Other

Seismic deficiency in walls: Limited ductility and the absence of tie columns diminishes shear strength.

Earthquake-resilient features in walls: Good transfer of seismic forces

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

Has seismic strengthening described in the above table been performed?: Yes, parapets are confined and non structural walls are isolated from the structure.

Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages?: The seismic strengthening was done in a new construction.

Was the construction inspected in the same manner as new construction?: N/A

Who performed the construction: a contractor or owner/user? Was an architect or engineer involved?: Usually engineers are involved.

What has been the performance of retrofitted buildings of this type in subsequent earthquakes?: Good seismic performance: parapets resist overturning forces and cracking effects were reduced in non structural walls..

Harmsen y Mayorca, 1997, de Estructuras de Concreto Armado, Pontificia Universidad Catolica del Peru.

Norma Peruana de Albanileria E-070, 1998, Capitulo Peruano del ACI.

Norma Peruana de Sismorresistente E-070, 1998, Capitulo Peruano del ACI.

Quiun, San Bartolome, Torrealva, Zegarra, 1997, El Terremoto de Nasca del 12 de Noviembre de 1996, Pontificia Universidad Catolica del Peru.

San Bartolome, 1994, Construcciones en Albanileria, Pontificia Universidad Catolica del Peru.

San Bartolome, Munoz, Rodriguez, 2001, Fuerzas as de para Edificaciones de Albanileria, Pontificia Universidad Catolica del Peru.