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whe [2019/01/22 16:29]
Vitor Silva
whe [2019/02/12 00:45] (current)
Vitor Silva
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-====== ​Mexico ​======+====== ​Italy ======
  
-===== Reinforced concrete multistory buildings ​=====+===== Historic masonry block of flats =====
  
 ==== 1. General Information ==== ==== 1. General Information ====
  
-**Report #:** 115+**Report #:** 206
  
 **Report Date:** 2010 **Report Date:** 2010
  
-**Country:​** ​Mexico+**Country:​** ​Italy
  
 **Housing Type:** masonry **Housing Type:** masonry
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 **Last Updated:** 2012 **Last Updated:** 2012
  
-**Regions Where Found:​** ​Buildings of this construction ​type can be found in four important regions in Mexico: 1.- Mexico City and metropolitan areacapital city of Mexicowith 30% of the total housing stock in the country2.- Guadalajara,​ Capital City of the State of Jalisco, high seismicity 3.- Monterrey, Capital City of the State of Nuevo Leon, low seismicity4.- Cities at resort areas of the Pacific coast, such as Acapulco, Ixtapa, Huatulco. This type of housing construction is commonly found in urban areas.+**Regions Where Found:​** ​This housing ​type is in Abruzzo RegionProvince ​of L Aquilaand is very frequent ​in small medieval villages built in mountainous areas 
 +90% of the Province ​of L Aquila is mountainous and about 50% of its municipalities have less than 1.000 inhabitantsUrban structures and buildings built since the Middle Age are very common
  
-**Summary:​** This report describes Reinforced Concrete (RC) multistory residential buildings in Mexico. This type of construction is found mostly in large cities where space limitations lead to this type of solution. Typically buildings of this type have eight or more stories. Members of the middle and upper classes are the target market for this type of construction. In areas of low seismic risk, waffle slab floor systems without structural RC walls are preferred by developers primarily due to their speed of construction. In areas of medium to high seismic risk, it is typical for this type of building to have a dual system, which combines RC moment frames and RC structural walls as the main lateral load resisting elements. The RC floor systems are constructed of waffle slabs or solid slabs. RC buildings account for about 80% of the entire housing stock in Mexico. Buildings constructed after 1985 are expected to perform well under seismic forces, especially in Mexico City, where the building construction code has been substantially updated to incorporate lessons learned during the 1985 earthquake. 
  
-**Length of time practiced:** 51-75 years+**Summary:** This housing type is typically built on sloped terrain (pic.1). Buildings share common walls with adiacent buildings and the average number of floors ranges from 3 to 5 (pic. 2). The ground floor is sometimes used as cellar or warehouse, whereas the upper floors are used for residential purposes. The walls are built using lime mortar to connect elements that are either bricks or rubble stones or a mix of both in which the bricks are positioned in thin layers every 1.5 2 m, in order to align and stabilize the stones. The last floor (attic) is sometimes more recent (probably from the beginning of the XX cent.) and built with different materials (i.e. tuff) or specific construction techniques (i.e. "muro a cassetta",​ whose bricks are positioned in order to made a very light structure). 
 +The floor structures are vaults of different shapes, materials and resistance depending on the function. At the lower levels they are usually thick and made of stones connected by lime mortar, whereas at the upper floors they are made by bricks. At the last level the vaults are usually made by one single brick layer and their sides are usually kept half empty with no walkable floor. 
 +The roof is made of timber and it is double pitched, sloping down towards the front and rear walls. This building type has shown a good seismic performance,​ because the adiacent blocks work all together to stand the earthquake. 
 +Strenghtening interventions have been carried out after the main earthquakes.
  
-**Still Practiced:** Yes+**Length of time practiced:** More than 200 years
  
-**In practice as of:** +**Still Practiced:** No
  
-**Building Occupancy:** Residential,​ 20-49 units+**In practice as of:** nan
  
-**Typical number of stories:** 10-25+**Building Occupancy:** Residential,​ 5-9 units
  
-**Terrain-Flat:​** ​Typically+**Typical number of stories:** 3-4 
 + 
 +**Terrain-Flat:​** ​Never
  
 **Terrain-Sloped:​** Typically **Terrain-Sloped:​** Typically
  
-**Comments:​** ​Comments here+**Comments:​** ​The building type dates back to the middle ages with a complex later evolution over time expecially since the 18th century.
  
  
 ==== 2. Features ==== ==== 2. Features ====
-**Plan Shape:** Rectangular, ​solid+**Plan Shape:** Rectangular, ​with an opening in plan
  
-**Additional comments on plan shape:​** ​+**Additional comments on plan shape:​** ​The plan and the overall shape of the buildings are influenced by the orography. People tried to build as much regurarly as possible, but the result were rectangules with not right angles and sides with very different measures. Sometimes walls are curved.
  
-**Typical plan length(meters):​** ​40+**Typical plan length(meters):​** ​3 - 4 
  
-**Typical plan width (meters):​** ​25+**Typical plan width (meters):​** ​3 - 4
  
-**Typical story height (meters):** 3.2+**Typical story height (meters):​** ​2.5 - 3.5
  
-**Type of Structural System:​** ​Structural ConcreteMoment Resisting FrameDual system Frame with shear wall+**Type of Structural System:​** ​MasonryStone Masonry WallsRubble stone (field stone) in mud/lime mortar or without mortar (usually ​with timber roof)Masonry:​ Unreinforced Masonry Walls: Brick masonry in mud/lime mortarMasonry:​ Unreinforced Masonry Walls: Brick masonry in mud mortar with vertical postsMasonry:​ Confined Masonry: Clay brick/tile masonry with wooden posts and beamsWooden Structure: Load-bearing timber frame: Masonry with horizontal beams/​planks at intermediate levels
  
-**Additional comments on structural system:​** ​The vertical load-resisting system is reinforced concrete moment resisting frame. Columns, beams and solid or waffle slabs. The lateral load-resisting system is reinforced concrete structural walls (with frame). Moment resisting frames ​are used in low seismic areas and dual systems ​(combination ​of frames and RC walls) are used in medium and high seismic areas. In dual systemsshear walls are usually located at the building core and moment frames are located at the building perimeter.+**Additional comments on structural system:​** ​In the same structure there are usually different construction ​systems
 +It depended mainly on the availability ​of building materialson the position of the single construction system as part of the overall structure ​and on the history of the buildings, to whom new rooms were added as families grew.
  
-**Gravity load-bearing & lateral load-resisting systems:​** ​+**Gravity load-bearing & lateral load-resisting systems:​** ​Gravity load-bearing system: thickness and materials depend on the floor level.  
 +Walls are thicker at the ground floor and thinner at the upper levels. They are usually made by a mix of bricks and rubble stones in which the bricks are positioned in thin layers every 1.5 - 2 m, in order to align and stabilize the stones.  
 +People used to reinforce perimetral corners placing shaped stones usually up to the 2nd floor. 
 +At the upper level there are often tuff walls or characteristic structures such as those called "muri a cassetta"​. They are made by two-wythe walls, in which every two courses of bricks laid edge on there is one course laid face-up, to connect the vertical bricks. The space between the vertical layers is empty, so that the thermal performance of the structure benefits from it and the wall is light. 
 +Vaults at the upper floors are often supported by timber frames filled by a partition made by a one-wythe wall, whose bricks are laid edge on. The load bearing structure and the partition are covered by plaster and the wall thickness is about 10 cm. 
 +The lime mortar joints are 3-5 mm thick.
  
-**Typical wall densities in direction 1:** 1-2%+**Typical wall densities in direction 1:** 10-15%
  
-**Typical wall densities in direction 2:** 1-2%+**Typical wall densities in direction 2:** 10-15%
  
-**Additional comments on typical wall densities:​** ​+**Additional comments on typical wall densities:​** ​nan
  
-**Wall Openings:​** ​Mostly 2 openings are constructed at floor levels, leaving space for elevators and stairsThese openings are commonly located at the center ​of floor systems ​and are surrounded by concrete walls, which are part of the lateral load resisting systemTheir sizes vary but typical dimensions ​are 2 x 5 m for stair ways and 2.5 x 2.5 m for elevators. Openings for doors are also located in RC walls. These walls are usually located at the building core and is unusual to locate RC walls at the building perimeter. Partitions in RC buildings for residential construction are usually constructed with clay/​concrete blocks.+**Wall Openings:​** ​Every room has usually one window on the external walls. 
 +They aligned ​the windows upright on the facades, but the needs of residents ​and owners changed over time so that the existing opening layout have been often modifiedMisalignments ​are very common. 
 +The openings account ​for approximately 10% -15% of the wall surface area.
  
 **Is it typical for buildings of this type to have common walls with adjacent buildings?:​** Yes **Is it typical for buildings of this type to have common walls with adjacent buildings?:​** Yes
  
-**Modifications of buildings:​** ​A typical pattern for the modification ​of RC buildings ​is the demolition of partitionswhich are not part of the lateral load system for the building.+**Modifications of buildings:​** ​Door and window openings have often been modified. Very frequent modifications are misalignments,​ enlargements,​ windows changed in balcony doors and windows bricked up and opened in different positions. 
 +The layout ​of apartments ​is quite irregular due to changes occurred over time.  
 +As families expandedthey built new storeys or just part of them or they bought rooms from the neighbours. This is the reason why inside the single flats there are often short flights of stairs and the plans are usually irregular, sometimes almost "​labyrinthine"​.
  
-**Type of Foundation:​** Shallow Foundation: Reinforced concrete isolated footingShallow Foundation: Reinforced concrete strip footingShallow Foundation: Mat foundationDeep Foundation: Reinforced concrete bearing pilesDeep Foundation: Reinforced concrete skin friction pilesDeep Foundation: Cast-in-place concrete piersDeep Foundation: Caissons 
  
-**Additional comments on foundation:** +**Type of Foundation:** Shallow Foundation: Rubble stone, fieldstone strip footing
  
-**Type of Floor System:** Other floor system+**Additional comments on foundation:** nan
  
-**Additional comments on floor system:** Structural concrete: Solid slabs (cast-in-place);​ Waffle slabs (cast-in-place);​ Flat slabs (cast-in-place);​ Solid slabs (precast) In most design of RC buildings for residential construction,​ all diaphragms are considered rigid.+**Type of Floor System:** Vaulted masonry floor
  
-**Type of Roof System:** +**Additional comments on floor system:** The traditional floor system is the vaulted masonry floor. 
 +We currently also find the shallow-arched masonry floor and the metal beams light flooring. The first one was introduced at the beginning of the XX cent and in particular after the earthquake occurred in 1915. The second one was introduced after the earthquake occurred in 1984.
  
-**Additional comments on roof system:** In most design of RC buildings for residential construction,​ all diaphragms are considered rigid. 
  
-**Additional comments ​section 2:** When separated from adjacent buildings, the typical distance from a neighboring building ​is 0.20 meters.+**Type of Roof System:** Wooden structure with light roof covering 
 + 
 +**Additional comments ​on roof system:** The traditional roof system ​is the wooden structure with light covering. 
 +We currently also find the cast-in-place metal beam-supported hollow flat tiles and concrete roof, which was introduced after the 1984 earthquake 
 + 
 +**Additional comments section 2:** nan
  
 ==== 3. Buildings Process ==== ==== 3. Buildings Process ====
  
 ^Structural Element ​ ^Building Material (s)  ^Comment (s)  | ^Structural Element ​ ^Building Material (s)  ^Comment (s)  |
-|Wall/​Frame ​ |Concrete|fc= 30 MPa+|Wall/​Frame ​ |Mix of bricks and rubble stones|average compressive strength: 256-413 N/cmq 
-|Foundations ​ |Concrete|fc= 25 MPa+average shear strength: 6.2 - 9.0 N/cmq 
-|Floors ​ |Concrete|fc= 25 MPa+(Baila, A., Binda, L., Borri, A. et al. (2011) - Manuale delle murature storiche, Analisi e valutazione del comportamento strutturale Vol.1, p. 292)
-|Roof  |Concrete|fc= 25 MPa+|Foundations ​ |Mix of bricks and rubble stones or rock|nan
-|Other ​ |||+|Floors ​ |Brick vaults|nan
 +|Roof  |Wooden beams|nan
 +|Other ​ |nan|nan|
 === Design Process === === Design Process ===
  
-**Who is involved with the design process?:​** ​Engineer or Architect+**Who is involved with the design process?:​** ​None of the above
  
-**Roles of those involved in the design process::​** ​Local building codes require that a project be designed ​by a registered engineer. Architects are in charge of the building space distribution and of fulfilling the owners requirements. Usually architects hire structural ​engineers ​for the design ​and construction of buildings.+**Roles of those involved in the design process::​** ​The construction process was carried out by masons, so engineers and architect were usually not involved
  
-**Expertise of those involved in the design::​** ​+ 
 + 
 + 
 +**Expertise of those involved in the design::​** ​nan
  
 === Construction Process === === Construction Process ===
  
-**Who typically builds this construction type?​** ​Other+**Who typically builds this construction type?​** ​Mason
  
-**Roles of those involved in the building process:​** ​Typically this construction ​type is built by developers.+**Roles of those involved in the building process:​** ​The construction ​was based on the mason'​s experience.  
 +Tricky works such as the construction of vaults were committed to specialized teams of masons
  
-**Expertise of those involved in building process:​** ​ 
  
-**Construction ​process ​and phasing:** RC buildings for residential ​construction in Mexico is mostly constructed by developersDepending ​on the type of soilexcavations for foundations is carried out with several types of excavator machineries. Ready-mix concrete is usually supplied for construction of these buildings. The construction of this type of housing takes place incrementally over time. Typically, the building ​is originally designed for its final constructed size.+**Expertise of those involved in building ​process:​** ​Masons were supposed to meet the owner'​s needs, working on a budget and using the construction ​materials available ​in the areaTheir main ability consisted in finding the right balance among forces acting in different directions ​on light and thin structures. They basically had to make sure that the stiffness ​of all the structural elements was coherent as a whole so thatin the event of an earthquake, the building ​would perform a box-behaviour.
  
-**Construction issues:​** ​+ 
 + 
 +**Construction process and phasing:** The construction process was influenced by the owner'​s budget, the availability of materials, the characteristics of the area (orography) and of the surrounding buildings. 
 +The works usually took place in one phase. Sometimes at a later time, storeys or just single rooms were added in order to meet the owner'​s needs. 
 +The construction tools were simple. 
 + 
 +**Construction issues:​** ​nan
  
 === Building Codes and Standards === === Building Codes and Standards ===
Line 115: Line 145:
 **Is this construction type address by codes/​standards?​** Yes **Is this construction type address by codes/​standards?​** Yes
  
-**Applicable codes or standards:​** ​There is not a national ​building code and only few local codes are available; thereforea number ​of regions in Mexico do not have building ​codesIn those cases some adaptations ​of the Mexico City building ​code are usedThis code covers RC design and in most parts is based on the ACI 318 codeIn some regions ​of the country where there is no local building code, the ACI 318 code is mostly followed. In Mexico Citythe title of the current building code is "​Reglamento de Construcciones del Distrito Federal"​ (Federal District Building Code). The year the first code/​standard addressing this type of construction issued was In Mexico City the first code provisions were issued in 1920 and the 1942 building code for Mexico City was the first that had seismic provisions. The most recent building code for Mexico City was released in 2004.+**Applicable codes or standards:​** ​With Royal Decree-Law n.573, on 29 April 1915 the area was included among the seismic ones, due to the earthquake occurred on 13 January ​ 2015. This Royal Decree-Law ruled both new construction and reparation works on damaged buildings (Title II Reconstructions,​ Title III Reparations) 
 + 
 +Relevant following regulations:​ 
 +- Royal Decree-Law n.2089, 23 October 1924 
 +Law n. 64, 2 February 1974, Provvedimenti per le costruzioni con particolari prescrizioni per le zone sismiche (Measure for constructions with specific rules for seismic areas) 
 +- Ministerial Decree 16 January 1996, Norme tecniche per le costruzioni in zone sismiche (Technical standards for constructions in seismic areas) 
 +- Ministerial Decree 14 January 2008, D.M. 2008 Norme Tecniche per le Costruzioni (Technical standards for constructions),​ which includes how to repair existing buildings made by bricks and stones. 
 + 
 +The standard currently in force is: Decree 17 January 2018, Aggiornamento delle "Norme tecniche per le costruzioni"​ (Update of the Technical standards for constructions). 
 + 
 +Technical suggestions and best practices are included in "Linee guida per riparazione e rafforzamento di elementi strutturali,​ tamponature e partizioni"​ written by ReLUIS consortium 
 + 
 +**Process for building code enforcement:​** nan 
 + 
 +=== 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** All these buildings are currently subjected to national ​and local codes that are much more recent than the constructions themselves 
 + 
 +=== Building Maintenance and Condition === 
 + 
 +**Typical problems associated with this type of construction:​** These buildings need structural strengthening due to their agetheir structural fragility, the poverty ​of their materials and even because throughout the centuries they have been subjected to several hearthquake tremors, which made them every time weaker (incremental damage)  
 + 
 +**Who typically maintains buildings of this type?** Owner(s) 
 + 
 +**Additional comments on maintenance and building ​condition** nan 
 + 
 +=== Construction Economics === 
 + 
 +**Unit construction cost:** This construction typology is no longer built and is usually replaced by other typologies made of reinforced concrete frames, whose cost ranges from 1.500 to 2.500 euros/sq m 
 + 
 + 
 + 
 +**Labor requirements:​** nan 
 + 
 +**Additional comments section 3:** nan 
 + 
 +=== 4. Socio-Economic Issues === 
 + 
 +**Patterns ​of occupancy:​** One family per 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:​** Family units are usually small (<=4 people) 
 +They are often retired people 
 + 
 +**Economic level of inhabitants:​** Low-income class (poor)Middle-income class 
 + 
 +**Additional comments ​on economic level of inhabitants:​** Retired people who live in these houses have often a low income. 
 +Families usually belong to the low or middle income class. 
 +Lots of houses are used as holiday homes by people from the area who live and work in other parts of the country. 
 +In villages with beautiful views sometimes apartments are bought by foreigners from high-income classwho spend there their holidays or few months out of the year 
 + 
 + 
 +**Typical Source ​of Financing:​** Owner financedPersonal savingsInformal network: friends or relativesSmall lending institutions/​microfinance institutionsOther 
 + 
 +**Additional comments on financing:​** State aid for the reparation ​and strengthening of the buildings after earthquakes 
 + 
 +**Type of Ownership:​** RentOwn outright 
 + 
 +**Additional comments on ownership:​** nan 
 + 
 +**Is earthquake insurance ​for this construction type typically available?​** No 
 + 
 +**What does earthquake insurance typically cover/​cost:​** nan 
 + 
 +**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:​** nan 
 + 
 +**Additional comments section 4:** nan
  
-**Process for building code enforcement:​** Building has to be designed by code requirements and plans need to be approved by a registered engineer. Plans are submitted to a code enforcement agency. However, usually the structural design is not reviewed by these agencies. It is assumed that the structural design is a responsibility only of the registered engineer. Building permits in Mexico City are granted by the local agency. In other parts of the country where there are local building codes these permits are granted by the corresponding local code enforcement agency. After the permit is granted, the code enforcement agency usually does not send inspectors to the construction site.+==== 5Earthquakes ====
  
 +^Year  ^Earthquake Epicenter ​ ^Richter Magnitude ​ ^Maximum Intensity ​ |
 +|1703|L'​Aquila|6.6|MI|
 +|1706|Campo di Giove (L'​Aquila)|6.6|MI|
 +|1762|Poggio Picenze (L'​Aquila)|5.9|MI|
 +|1904|Rosciolo (Marsica)|5.6|MI|
 +|1915|Paterno (Marsica)|7|MI|
  
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