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| reports:report_83 [2025/04/29 15:16] – created - external edit 127.0.0.1 | Changed string Earthquakes [2025/11/13 09:18] (current) – created minor |
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| **Last Updated:** | **Last Updated:** |
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| **Regions Where Found:** Buildings of this construction type can be found in all major urban areas in the country. This type of housingconstruction is commonly found in urban areas. | **Regions Where Found:** Buildings of this construction type can be found in all major urban areas in the country. This type of housing construction is commonly found in urban areas. |
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| **Summary:** This multi-family urban housing construction waspracticed in Romania between the 1960s and1990s. The load-bearing system is a precastreinforced concrete large panel construction.Buildings of this type are typically highrises (10or 11 stories high), although there are also lowtomedium-rise buildings (4 to 8 stories high) ofthis construction type (with different structuraldetails). In general, buildings of this type are ofrectangular plan, with honeycomb ("fagure")layout, housing typically four apartments perfloor. Wall panels are laid in both the longitudinaland the transverse direction. The panels aremechanically coupled at the base, withcontinuous vertical reinforcement bars.This region is well known as a seismically pronearea, with the epicentre of damagingearthquakes close to Vrancea. Earthquakes withthe Richter magnitude of over 7.0 occur onaverage every 30 years. Bucharest, the capital,is located around 150 km south of the epicentreand lies in the main direction of the propagationof seismic waves. The Bucharest area is locatedon the banks of the Dmbovita and Colentinarivers, on nonhomogenous alluvial soil deposits.During the earthquake of 4 March 1977 (Richtermagnitude 7.2), over 30 buildings collapsed inBucharest, killing 1,424 people. There was nosignificant damage reported to the buildings ofthis construction type in the 1977 earthquake.Consequently, this construction technique hascontinued to be practiced since the earthquake.The building described in this report was builtafter the 1977 earthquake, and has not beenexposed to damaging earthquakes so far. | **Summary:** This multi-family urban housing construction was practiced in Romania between the 1960s and 1990s. The load-bearing system is a precast reinforced concrete large panel construction.Buildings of this type are typically highrises (10or 11 stories high), although there are also low to medium-rise buildings (4 to 8 stories high) of this construction type (with different structural details). In general, buildings of this type are of rectangular plan, with honeycomb ("fagure") layout, housing typically four apartments per floor. Wall panels are laid in both the longitudinal and the transverse direction. The panels are mechanically coupled at the base, with continuous vertical reinforcement bars.This region is well known as a seismically prone area, with the epicentre of damaging earthquakes close to Vrancea. Earthquakes with the Richter magnitude of over 7.0 occur on average every 30 years. Bucharest, the capital, is located around 150 km south of the epicentre and lies in the main direction of the propagation of seismic waves. The Bucharest area is located on the banks of the Dmbovita and Colentina rivers, on non homogenous alluvial soil deposits.During the earthquake of 4 March 1977 (Richter magnitude 7.2), over 30 buildings collapsed inBucharest, killing 1,424 people. There was no significant damage reported to the buildings of this construction type in the 1977 earthquake.Consequently, this construction technique has continued to be practiced since the earthquake.The building described in this report was builtafter the 1977 earthquake, and has not been exposed to damaging earthquakes so far. |
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| **Length of time practiced:** Less than 25 years | **Length of time practiced:** Less than 25 years |
| ==== 2. Features ==== | ==== 2. Features ==== |
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| {{gallery>:reports:report_83?rp83_features_*.jpg&200x200&lightbox&crop&4 | }} | {{gallery>:reports:report_83?rp83_features_*.jpg&1200x1200&lightbox&crop&4}} |
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| **Plan Shape:** Rectangular, solid | **Plan Shape:** Rectangular, solid |
| **Type of Structural System:** Structural Concrete: Precast Concrete: Shear wall structure with precast wall panel structure | **Type of Structural System:** Structural Concrete: Precast Concrete: Shear wall structure with precast wall panel structure |
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| **Additional comments on structural system:** This building type is characterized by a so-called "honeycomb" ("fagure" in Romanian) building plancharacteristic for Romanian housing design - the same system is described for the "OD" housing type(World Housing Encyclopedia Report 78). It consists of box-type units creating rooms. Due to such abuilding configuration, the walls are well connected and are able to carry the loads in a uniform manner.Floor structures are 120 mm thick reinforced concrete solid slabs supported by the loadbearing walls.Typical wall-floor connection is illustrated in Figure 13. These buildings are supported by mat foundations.The basement walls are cast-in-place.The special feature of the building described in this report is that the facade walls are non-loadbearingstructures of lightweight block masonry construction. In some buildings of this construction type, precastconcrete wall panels are used as faade elements. The interior wall panels are of solid concreteconstruction - in this case, there is no need for a 3-layered panel section with thermal insulation in themiddle (typical for the faade wall panels).The load-bearing walls are laid in two principal directions, as illustrated in Figure 9. In general, there aretwo interior walls in the longitudinal direction and nine walls in the transverse direction; it should be notedthat four transverse walls are continuous over the building width, whereas the other five walls are shorter.In addition, there are lightweight concrete partition walls, some of which have been removed in buildingrenovations carried out by owners.The main lateral load-resisting structure consists of 200 mm precast reinforced concrete wall panelssupported by RC slabs (walls in pre-1977 buildings are typically 140 mm thick). The wall panels form abox of room size ("panouri mari"). The lateral stability is provided by the columns tied to the wall panels,as illustrated in an example of corner panels, see Figure 12. Boundary elements are used instead of thecolumns as "stiffening" elements at the exterior (as shown in Figure 10). According to NBS (1977), themechanical union of wall panels in the joints is achieved by means of splice bars welded to the transversereinforcement of adjacent panels. Longitudinal bars, used singly in vertical joints and in pairs in horizontaljoints, provide an added bearing area for the transfer of tension across the connections. The coupling ofthe floor panels is somewhat different, as illustrated in Figure 15. The top bars are splice welded whilethe bottom bars are bent up 90 degrees and lapped. This particular scheme gives greater continuity to thefloors at the supports than the lapped loop arrangement used in the high-rise building system. The wallpanels are mechanically coupled at their base, as illustrated in Figure 16, so that all vertical bars arecontinuous across the horizontal joints (it should be noted that in the case of the high-rise building panelconnections only the longitudinal bars of vertical joints are coupled). | **Additional comments on structural system:** This building type is characterized by a so-called "honeycomb" ("fagure" in Romanian) building plan characteristic for Romanian housing design - the same system is described for the "OD" housing type (World Housing Encyclopedia Report 78). It consists of box-type units creating rooms. Due to such a building configuration, the walls are well connected and are able to carry the loads in a uniform manner.Floor structures are 120 mm thick reinforced concrete solid slabs supported by the load bearing walls.Typical wall-floor connection is illustrated in Figure 13. These buildings are supported by mat foundations.The basement walls are cast-in-place.The special feature of the building described in this report is that the facade walls are non-load bearing structures of lightweight block masonry construction. In some buildings of this construction type, precast concrete wall panels are used as facade elements. The interior wall panels are of solid concrete construction - in this case, there is no need for a 3-layered panel section with thermal insulation in the middle (typical for the facade wall panels).The load-bearing walls are laid in two principal directions, as illustrated in Figure 9. In general, there are two interior walls in the longitudinal direction and nine walls in the transverse direction; it should be noted that four transverse walls are continuous over the building width, whereas the other five walls are shorter.In addition, there are lightweight concrete partition walls, some of which have been removed in building renovations carried out by owners. The main lateral load-resisting structure consists of 200 mm precast reinforced concrete wall panels supported by RC slabs (walls in pre-1977 buildings are typically 140 mm thick). The wall panels form a box of room size ("panouri mari"). The lateral stability is provided by the columns tied to the wall panels, as illustrated in an example of corner panels, see Figure 12. Boundary elements are used instead of the columns as "stiffening" elements at the exterior (as shown in Figure 10). According to NBS (1977), the mechanical union of wall panels in the joints is achieved by means of splice bars welded to the transverse reinforcement of adjacent panels. Longitudinal bars, used singly in vertical joints and in pairs in horizontal joints, provide an added bearing area for the transfer of tension across the connections. The coupling of the floor panels is somewhat different, as illustrated in Figure 15. The top bars are splice welded while the bottom bars are bent up 90 degrees and lapped. This particular scheme gives greater continuity to the floors at the supports than the lapped loop arrangement used in the high-rise building system. The wall panels are mechanically coupled at their base, as illustrated in Figure 16, so that all vertical bars are continuous across the horizontal joints (it should be noted that in the case of the high-rise building panel connections only the longitudinal bars of vertical joints are coupled). |
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| **Gravity load-bearing & lateral load-resisting systems:** | **Gravity load-bearing & lateral load-resisting systems:** |
| **Additional comments on typical wall densities:** The typicalstructural wall density is 5% - 7% Wall density is larger in the transverse direction. | **Additional comments on typical wall densities:** The typicalstructural wall density is 5% - 7% Wall density is larger in the transverse direction. |
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| **Wall Openings:** There are between 20 and 30 windows per floor. Each room has one window and one door, except forthe corridors (larger number of doors). Windows constitute around 25% of the exterior wall area, whereasdoors constitute less than 15% of the interior wall area. | **Wall Openings:** There are between 20 and 30 windows per floor. Each room has one window and one door, except forthe corridors (larger number of doors). Windows constitute around 25% of the exterior wall area, whereas doors constitute less than 15% of the interior wall area. |
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| **Is it typical for buildings of this type to have common walls with adjacent buildings?:** No | **Is it typical for buildings of this type to have common walls with adjacent buildings?:** No |
| **Additional comments on roof system:** Solid slabs (cast-in-place); Solid slabs (precast) | **Additional comments on roof system:** Solid slabs (cast-in-place); Solid slabs (precast) |
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| **Additional comments section 2:** Whenseparated from adjacent buildings, the typical distance from a neighboring building is 2.5 meters. | **Additional comments section 2:** When separated from adjacent buildings, the typical distance from a neighboring building is 2.5 meters. |
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| ^ Structural Element ^ Building Material (s) ^ Comment (s) ^ | ^ Structural Element ^ Building Material (s) ^ Comment (s) ^ |
| | Wall/Frame | Reinforced concrete:Steel | Steel PC 52 - steel yieldstrength 350 MPa; Concrete:around 1970s, typicalconcrete strength was in therange of 25 MPa (cubestrength)Information onconcrete and steelproperties is inagreement with thereports after the1977 earthquake(e.g. NBS 1977) | | | Wall/Frame | Reinforced concrete:Steel | Steel PC 52 - steel yield strength 350 MPa; Concrete:around 1970s, typical concrete strength was in the range of 25 MPa (cube strength)Information on concrete and steel properties is in agreement with the reports after the1977 earthquake(e.g. NBS 1977) | |
| | Foundations | | | | | Foundations | | | |
| | Floors | | | | | Floors | | | |
| === Design Process === | === Design Process === |
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| **Who is involved with the design process?** EngineerArchitectOther | **Who is involved with the design process?** Engineer Architect Other |
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| **Roles of those involved in the design process:** The building design was developed by "Design Institutes", which employ trained technical specialists,including engineers and architects. | **Roles of those involved in the design process:** The building design was developed by "Design Institutes", which employ trained technical specialists, including engineers and architects. |
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| **Expertise of those involved in the design process:** The building design was developed by "Design Institutes", which employ trained technical specialists,including engineers and architects. | **Expertise of those involved in the design process:** The building design was developed by "Design Institutes", which employ trained technical specialists, including engineers and architects. |
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| **Roles of those involved in the building process:** Buildings of this type were financed by government housing funds and were built by construction companies. | **Roles of those involved in the building process:** Buildings of this type were financed by government housing funds and were built by construction companies. |
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| **Expertise of those involved in building process:** The construction was made by technical specialists employed by theconstruction companies using the specialized equipment. The construction was additionally supervised bya special unit called "State Inspection for Buildings". | **Expertise of those involved in building process:** The construction was made by technical specialists employed by the construction companies using the specialized equipment. The construction was additionally supervised by a special unit called "State Inspection for Buildings". |
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| **Construction process and phasing:** The construction was performed using specialized equipment for prefabricated construction. The construction of thistype of housing takes place in a single phase. Typically, the building is originally designed for its final constructedsize. In some cases, new building blocks were built at the same location; however,these new blocks were built as completely new buildings with their own walls and foundations. | **Construction process and phasing:** The construction was performed using specialized equipment for prefabricated construction. The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size. In some cases, new building blocks were built at the same location; however, these new blocks were built as completely new buildings with their own walls and foundations. |
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| **Construction issues:** | **Construction issues:** |
| **Is this construction type address by codes/standards?** Yes | **Is this construction type address by codes/standards?** Yes |
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| **Applicable codes or standards:** This construction type is addressed by the codes/standards of the country. P-100-81. The year the firstcode/standard addressing this type of construction issued was 1981. The most recent code/standard addressing thisconstruction type issued was 1992. | **Applicable codes or standards:** This construction type is addressed by the codes/standards of the country. P-100-81. The year the first code/standard addressing this type of construction issued was 1981. The most recent code/standard addressing thisconstruction type issued was 1992. |
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| **Process for building code enforcement:** Information not available. | **Process for building code enforcement:** Information not available. |
| **Is this construction typically authorized as per development control rules?** Yes | **Is this construction typically authorized as per development control rules?** Yes |
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| **Additional comments on building permits and development control rules:** Building permits were required in the period when this construction was practiced. Building inspections wereperformed by the construction company staff and also by a special government department called "State ConstructionInspection." | **Additional comments on building permits and development control rules:** Building permits were required in the period when this construction was practiced. Building inspections were performed by the construction company staff and also by a special government department called "State ConstructionInspection." |
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| ==== 4. Socio-Economic Issues ==== | ==== 4. Socio-Economic Issues ==== |
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| **Patterns of occupancy:** One family per housing unit.Each building typically has more than 100 housing unit(s). 150 units in each building. In general, there are 48 to 54housing units per building block. Each building block is centered around a staircase. There are usually between oneand five building blocks in a typical building complex. | **Patterns of occupancy:** One family per housing unit.Each building typically has more than 100 housing unit(s). 150 units in each building. In general, there are 48 to 54housing units per building block. Each building block is centered around a staircase. There are usually between one and five building blocks in a typical building complex. |
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| **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 day:** >20 |
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| ==== 5. Earthquakes ==== | ==== 5. Seismic Vulnerability ==== |
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| === Past Earthquakes in the country which affected buildings of this type=== | === Past Earthquakes in the country which affected buildings of this type=== |
| === Past Earthquakes === | === Past Earthquakes === |
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| **Damage patterns observed in past earthquakes for this construction type:** No damage to buildings of this type was observed in the 1986 and 1990earthquakes. In the 1977 earthquake (M 7.2 ), no significant damage was observed to other buildings ofsimilar construction. | **Damage patterns observed in past earthquakes for this construction type:** No damage to buildings of this type was observed in the 1986 and 1990earthquakes. In the 1977 earthquake (M 7.2 ), no significant damage was observed to other buildings of similar construction. |
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| **Additional comments on earthquake damage patterns:** According to the reports on the 1977earthquake (Balan et al. 1982), somebuildings of this type experiencedcracking in the wall panel connectionarea, especially at the wall corner jointsand intersections, and wall-floorconnections. In some cases, those wereexisting cracks that were widened inthe 1977 earthquake. However, in thecity of Lasi (north of the epicentre), 45cracks developed in the walls especiallyabove the openings and around thestaircases in some 8-storey buildingsbuilt around 1960. | **Additional comments on earthquake damage patterns:** According to the reports on the 1977earthquake (Balan et al. 1982), some buildings of this type experienced cracking in the wall panel connection area, especially at the wall corner joints and intersections, and wall-floor connections. In some cases, those were existing cracks that were widened in the 1977 earthquake. However, in the city of Lasi (north of the epicentre), 45cracks developed in the walls especially above the openings and around the staircases in some 8-storey buildings built around 1960. |
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| **Seismic deficiency in walls:** | **Seismic deficiency in walls:** |
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| **Earthquake-resilient features in walls:** - Large panel stiffness; redundancyprovided by several wall panels in bothdirections with frequent cross walls;regular and symmetric plan; goodquality of concrete construction. | **Earthquake-resilient features in walls:** - Large panel stiffness; redundancy provided by several wall panels in both directions with frequent cross walls; regular and symmetric plan; good quality of concrete construction. |
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| **Seismic deficiency in frames:** | **Seismic deficiency in frames:** |
| For information about how seismic vulnerability ratings were selected see the {{ :wiki:seismic_vulnerability_rating.pdf | Seismic Vulnerability Guidelines}} | For information about how seismic vulnerability ratings were selected see the {{ :wiki:seismic_vulnerability_rating.pdf | Seismic Vulnerability Guidelines}} |
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| | ^ High vulnerabilty ^^ Medium vulnerability ^^ Low vulnerability ^^ | | ^ High vulnerability ^^ Medium vulnerability ^^ Low vulnerability ^^ |
| | | A | B | C | D | E | F | | | | A | B | C | D | E | F | |
| | Seismic vulnerability class | | | %%|-%% | o | %%-|%% | | | | Seismic vulnerability class | | | %%|-%% | o | %%-|%% | | |
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| **Additional comments section 5:** Information on earthquake damage patterns is based on other buildings of similarconstruction that experienced the 1977 earthquake. The building described in this report was built afterthe 1977 earthquake. | **Additional comments section 5:** Information on earthquake damage patterns is based on other buildings of similar construction that experienced the 1977 earthquake. The building described in this report was built after the 1977 earthquake. |
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| **Additional comments on seismic strengthening provisions:** | **Additional comments on seismic strengthening provisions:** |
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| **Has seismic strengthening described in the above table been performed?** Based on the good performance of buildings of similar construction in the 1977 earthquake, it isconsidered that retrofit is not required. | **Has seismic strengthening described in the above table been performed?** Based on the good performance of buildings of similar construction in the 1977 earthquake, it is considered that retrofit is not required. |
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| **Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages?** | **Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages?** |
