Prefabricated metal construction of the Modern Movement, Germany

From World Housing Encyclopedia


1. General Information

Report: 95

Building Type: Prefabricated metal construction of the Modern Movement

Country: Germany

Author(s): Maria D. Bostenaru

Created on: 7/4/2003

Last Updated: 7/11/2004

Regions Where Found: Buildings of this construction type can be found in Karlsruhe (1929 Dammerstock: Fig. 3, 4), Frankfurt, Berlin,Stuttgart (1927 Weissenhof: Fig. 6), Kassel (1929 Rothenberg), Celle (1930 Blumlagerfeld) and others. Some 300,000 residential units (see “Weisse Vernunft”, 1999). This type of housing construction is commonly found in sub-urban areas.

Summary: This urban housing construction was practiced for about 20 years during the early 1900s in Germany. Single-family houses and blocks of flats, both built according to the same construction system, are included in this report. This construction was built in what were once the outlying areas of German cities. Typically, these low-cost housing units are rented by the residents. The buildings consist of a row of several individual, 20-meter-long units, each of which usually contains two apartments on each floor. The load-bearing system is iron skeleton with brick infill. Usually, the skeleton is made out of columns and beams, but dense column grids were sometimes used to minimize the spans of metal joists as a cost-saving measure.Experiments with various materials for the bricks were tried as part of the continuous search for improved insulation. The floors are also made out of bricks on iron joists. Stiffening is usually provided by diagonal ties at the staircases, which are placed in the middle of each building unit. Because of the seismic activity, both along the Rhine and in the Swabian Jura affecting Baden-Wuerttemberg, seismic codes (DIN) were issued in 1981 and have been updated. Standards have existed since 1957 and are expected to be included in the new European code, Eurocode 8.

Length of time practiced: Less than 25 years

Still Practiced: No

In practice as of: This construction type had been practiced up to the world economy crisis.

Building Occupancy: Residential, 24 units

Typical number of stories: 2-4

Are buildings of this type typically built on flat or sloped terrain? Flat terrain only

Comments: This construction type was both used for single family housing and multiple housing units, but multiple housing units were more common. See figures 7 and 8 for typical views in a Siedlung.


2. Features

Plan Shape: Rectangular, solid

Additional comments on plan shape: None

Typical plan length (meters): 20-160

Typical plan width (meters): 5.5-8.5

Typical story height (meters): 2.8

Typical span(meters): 3.0

Type of Structural System: Steel - Moment Resisting Frame - With brick masonry partitions

Additional comments on structural system: Typical schelet with I shaped members is shown in Ahnert (2002) Vol. III in Table 10 on page 41.

Gravity load-bearing & lateral load-resisting systems:

Lateral Load-Resisting System: Lateral load resistance is provided by iron skeleton stiffened by brick infill walls (fig. 21) and by wind bracing within the staircase walls (fig. 20). The floor is the so called“Kleine” brick-iron-floor system with I-profile joists. The “Kleine” floor system was characterized through concrete reinforced with round iron bars at about 30cm distance.

Gravity Load-Bearing Structure: The vertical load-resisting system is iron skeleton (fig. 11-13) with infill walls of half clay or“Schwemmstein” bricks support the gravity loads. The connections are made with screws over corner elements in the upper floors and in the basements and at column base with nits (fig. 16). The statics were computed for a 10cm thick brick-iron floor. Iron/steel frames are one story high and later infilled with masonry (Stuttgart, Karlsruhe). In Celle many joists are missing and vertical load bearing elements are spaced 85cm. Gravitational loads are transmitted directly to the foundation. Here the skeleton serves as “Fachwerk” up to the cornice.

Typical wall densities in direction 1: 5-8%

Typical wall densities in direction 2: 5-8%

Additional comments on typical wall densities: The typical structural wall density is 5 - 8%. This density is given for infill walls.

Wall Openings: The openings are usually 85cm wide, which also determined the spacing of metal elements used, for example in Celle (where many joists were missing). Images showing details of openings in mid-rise buildings can be seen in figure 17 (long facade of a typical building bar) and 19 (short facade of a typical building bar). The size and the distribution of windows in a typical low-rise building can be seen in figure 12.

Is it typical for buildings of this type to have common walls with adjacent buildings?: Yes

Modifications of buildings: The original light walls were later replaced by the masonry partition walls. The empty rooms were later used for residential occupancy.

Type of Foundation: Shallow Foundation - Reinforced concrete isolated footing

Additional comments on foundation: None

Type of Floor System: Steel - Composite steel deck and concrete slab, composite masonry and steel joist

Additional comments on floor system: Ahnert (2002) shows the details of such a structure in Table 6 on page 36, Vol.III (with “Kleine” floor). More details are given in the “Kleine” floor in Table 18 on page 57 in Ahnert (2002), Vol. II. Here and in the adjacent Table 17 also another floor system of the same type (I joists and holed bricks) was used in Germany for common buildings at that time: “Secura”, “Wingen”, “Kelling”, “Rhein”, “Frster”, “Ludwig” and finally“Hourdis”. Hourdis is the French name for hollow bricks. This system was also used with “Bimsbeton” (special kind of concrete, based on pumice). All these systems are unreinforced floor system types. Later on round steel was used to bind the I joists (see Ahnert, 2002, Vol. II, Table 22 on page 164) to the exterior walls and within these with higher density in the basement (Ahnert, 2002, vol. II, Table 23, page 65). With added round steel wide variations of the floor type, called “Stahlsteindecken” (steel stone floors) were created and some of them from 1936 are shown in Ahnert(2002), Vol. II, in Table 25 on page 78 and Table 26 on page 79. These were addressed from 1943 on by the code DIN1046. Later cross reinforcing of such floors was possible, as documented by Ahnert (2002), Vol. II, Table 31 on page 88.

Type of Roof System: Structural concrete - Solid slabs (cast in place or precast)

Additional comments on roof system: None

Additional comments section 2:

Typical Plan Dimensions: Typically a building is divided into rectangular units of about 20m long, separated by joints. One to eight such units can form a building, the typical number being 3 to 5 (Fig. 9 and 10). An aerial view today of a typical settlement showing these relationships can be seen at http://www1.karlsruhe.de/Stadtteile/Weiherfeld-Dammerstock/Bilderbogen/luft-dam.jpg ) or http://www1.karlsruhe.de/Stadtteile/Weiherfeld-Dammerstock/bilder_quu.php).

Typical Number of Stories: The typical number of stories for multiple housing units vary from 2 to 4 depending on the region. The average number of stories is 4 (1 ground floor (GF) +3 regular) in Stuttgart (fig. 5), 4 (1 basement + GF +3 regular) in Kassel and in Karlsruhe (fig. 1) . The single family houses are 2story (1 basement+ GF +1 regular) in Celle and Karlsruhe (fig. 2).

Typical Span: For typical buildings the spans in unreinforced systems are 1-2m (and rarely 3-4 m). In the cases where anchors were used, the spans were around 2.5mand in case of “Stahlsteindecken” it is approximate 3m. By 1925, the spans for no iron were usually 1.3-1.4m. In the dry-mounting application the spacing is 1.06 m. The span for example buildings: 3.2 m all at facade in longitudinal direction except at staircase where 1.8m; 4.8 the long ones in transversal direction (the short ones remaining 3.6 m). Other buildings have spans of 0.85, 1.06 for the secondary joists.

Most prominent buildings of this type show the same characteristics of the load bearing and structural system type, including the type of foundation and roof/floor system. Notable exceptions are two specially optimised examples: a dry system building and the one, where through columns laying close to each other. Differences appear in the kind of bricks used, as shown in Section 7.1. Iron joists and columns had been used in Germany since 1860, however, the simultaneous use of both in a schelet was rare at the beginning. The norms for the use of “old steel” were still updated in 1947. Spans of 2-4m were usual. After 1900 steel schelet had been used in common residential buildings, like an example in Ahnert, Vol. III, P. 31 from 1928 (originally from Maul, 1929). This kind of structure was more usual for business use though.


3. Building Process

Description of Building Materials

Structural Element Building Material (s) Comment (s)
Wall/Frame Infill Walls: Hollow clay brick or other stone Tekton cover inside reinforced with steel on both sides of light isolating concrete filling (Karlsruhe) OR pumice concrete with tekton cover. Basement Walls: simple concrete (not reinforced) Basement Walls: B50-B225 (prescribed since 1894). Brick masonry: 12cm thick tekton cover 6-10 cm thick 25- 12- 6.5 cm (“Reichsformat”) in 1870. System Benzinger (the name given to a mounting construction system out of“stau” bricks and frames)
Foundations Concrete
Floors Floors: Hollow clay brick and I iron profiles, sometimes brick and RC (concrete reinforced with round iron bars) (Stuttgart) OR pumice cement floorboards with over concrete (Celle) OR cement holed floorboards on T steel joints with over concrete (Karlsruhe) with pumice over concrete OR pumice floorboards on I joists (Stuttgart) 10 cm thick - 1.25 kN/m²;12 cm thick - 1.5 kN/m². The“Kleine” floor (fig. 15) had 15 cm thickness for 2.85 m span and 10cm thickness for 1.90 m span prescribed for housing. Over concrete in the middle: B80, at the ends:B120. “Lochstein” (holed brick)10 x 15 x 25 cm or10x12x25cm. Mortar:1:1:5-6 (cement:calc:sand). Round steel for reinforcement: diameter of 5,6,7,8,9,10 cm… or mixed 8+10, 10+12cm… System Benzinger
Roof Roof: RC (Stuttgart) OR pumice concrete (Celle) OR cement holed floorboards on T steel joints with over concrete (Karlsruhe) System Benzinger
Frame iron/steel See tables for typical loads for computing columns as well as computation examples in Ahnert vol. III, P. 23-42. See tables for typical loads for computing joists as well as computation examples in Ahnert vol. III, P. 9-16. Double T profiles OR Z profiles for columns, I profiles for joists. In mortar - System Benzinger for mounting OR dry mounted Typical construction details are shown in Ahnert vol. III on page 32 (Table 6) and page 41(Table 10)

Notes:

1. Although the design calculation rules for iron-concrete spread from Germany to eastern Europe, few applications with iron-concrete construction are known. Even in case of the few known examples for this, iron-concrete load bearing elements are combined with interior iron/steel columns (fig. 18), and the only difference consists in the floor structures, which are supported by RC beams. Iron-concrete columns are embedded into the hollow bricks of pumice, which form a permanent scaffolding. Concrete is used in “casting and pouring process”. Design calculations for iron-concrete columns are explained in Ahnert vol. III P. 42-49, typical reinforcement details on page 46 (Tafel 12) According to “Betonkalender” B50=50kg/cm² (5 N/m²) Since 1917 the DIN (Deutsche Industrie Norm = German Industrial Code) has been in use. Bricks were addressed by DIN105 (since 1922), steel by DIN1050 (since 1937), iron by DIN1051 (since 1937), Page 12 members out of stone by DIN1053 (since 1937), foundations by DIN1054 (since 1940) and load assumptions by DIN1055 (since 1934).

2. The architect Gropius tried out experimentally dry mounting of light steel skelet construction (ie without use of mortar). In this case, instead of masonry infill walls a wall construct with air core was used. Such a wall corresponded regarding the termal isolation possibility to a 1.5m clay masonry wall.

Design Process

Who is involved with the design process? Engineer, Architect

Roles of those involved in the design process: Engineers had a technical role. High enterprises constructing bridges and industrial facilities came into the market of small houses. Architects acted as managers and designers of the construction process. Architects envisaged the optimization of housing prices. They designed building element types for industrial serial production while accounting for spatial considerations as well. Some German architects came back after a stay in the USA where prefabrication and rationalization were used more.

Expertise of those involved in the design process: Columns for this type of building have been addressed by standards since 1876 and by norms (DIN) since 1934. The last DIN addressing them is DIN4114 released in 1952. Joists for this type of building have been addressed by standards since 1876 and by norms since 1934. The DIN1050 was updated in 1937 and 1947 retained its name.


Construction Process

Who typically builds this construction type? Other

Roles of those involved in the building process: No. This construction type was typically built as social housing.

Expertise of those involved in building process: Columns for this type of building have been addressed by standards since 1876 and by norms (DIN) since 1934. The last DIN addressing them is DIN4114 released in 1952. Joists for this type of building have been addressed by standards since 1876 and by norms since 1934. The DIN1050 was updated in 1937 and 1947 retained its name.

Construction process and phasing: New construction methods: Central ideas were rationalization, typisation and standardization. Industrial mounting methods aimed saving in time and costs. The construction flow had to be optimized in a process plan (see an example of processual planing in an axonometrical construction schema of Walter Gropius in “Weisse Vernunft”, 1999). This time the Net Plan so used today has come to life as the model used for process planning was similar to the net plan of operating railways (or to machine models Ford's). All elements which could be prefabricated were done so. Then instead manufacturing construction machines had been extensively employed. The construction flow was optimized regarding the employment of construction machines. This could be only done due to the line-shaped planimetry of the Siedlungen of that time. Regarding the construction technique itself the prefabricated building elements used to be mounted. In case of dry mounting the house could be inhabitated immediately after being finished. First the skeleton was made, one week after that the surface on the ground was made, about ten days later the walls with openings, for which an exterior screening was needed, were constructed. For characteristic images see Stein Holz Eisen P. 769). The walls of the staircases were infilled first, then the other exterior walls (with windows) from the bottom to the top (fig.23-24) were placed. For an archive photo of a low-rise building of this type during construction process seehttp:www1.karlsruhe.de/Stadtteile/Weiherfeld-Dammerstock/bau-damm_1.jpg (orhttp:www1.karlsruhe.de/Stadtteile/Weiherfeld-Dammerstock/bilder_v.php) In certain cases the construction without using any wet techniques was proposed, so that the house could be occupied right after the rough structure was completed. 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: Not provided


Building Codes and Standards

Is this construction type address by codes/standards? Yes

Applicable codes or standards: The year the first code/standard addressing this type of construction issued was In 1917, the first code (DIN = [Deutsche Industrie Norm] =“German Industrial Standard”) for the construction industry appeared. The board was initiated by Muthesius, Behrensand the Deutsche Werkbund. The most recent code/standard addressing this construction type issued was DIN4149 [Bauten in deutschen Erdbebengebieten - Lastannahmen, Bemessing und Ausfhrung blicher Hochbauten] =“Building in German earthquake regions - loading assumptions, dimensioning and execution of common buildings”was issued in 1981. This then became a technical prescription.

Process for building code enforcement: First standards for earthquake safe buildings in Baden Wrttemberg appeared in 1957 and 1972. Since 1981 (this means after the earthquake from Swabian Alb in 1978) the DIN 4142 has been used. It is foreseen that this will appearin the Eurocode 8. For details see: http://www.lgrb.uni-freiburg.de/d/akt/lgrb_n0202.pdf.


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: None


Building Maintenance and Condition

Typical problems associated with this type of construction: Construction changed from its original “statical” design, like: interior masonry walls were added instead of initial light partition walls bringing supplementary loads to the metal joists; floor slabs became thicker than designed, finishings got heavier (due to heavy self weight); change in occupancy: from empty rooms to residential use; strengthening of metal load bearing structure with supplementary welded parts was not always possible due to the material properties of the iron used; floors partially deformed (till 5cm); bad phonoisolation. More details are explained in Nägele(1992), P. 112-114

Who typically maintains buildings of this type? Other

Additional comments on maintenance and building condition: None


Construction Economics

Unit construction cost: Generally 10-15% cheaper than traditional building. Otto Haesler is one of the few architects who reached a notable cost sinking through rationalization in this type of building. The material price of steel was low at the time. According to “Weisse Vernunft”(1999): the cost for multiple housing unit of this type is 52RM/m; and for dry mounting example is 80RM/m. Other buildings of innovative type cost 64 (example with iron-concrete)-85 RM/m. RM =Reichsmark. Workmanship prices of the time were approx. 1.5 RM/h, while material prices looked like: ~50RM/1 tcement, ~70RM/1m gravel, ~200RM/1t steel (after Ahnert, 2002, vol. I, P. 13).

Labor requirements: Realization in record speed owes to the optimized construction flow, the so-called Taylorisation. Most of the construction is based on the extensive prefabrication of parts. The size of prefabricated parts was dictated by the lifting force of the machinery or eventually of a worker, although manual work had been tried to be avoided. The construction site management becomes almost like managing industrial lines. For further examples, including numerous films of prefabrication and construction process, see “Weisse Vernunft” (1999): [Baustelle] (=“construction site”). Ex. on the Gropius building site in Dessau-Trten 130 residential units were constructed in 88 working days, i.e. 5 1/2 days for one unit. The Gropius siedlung there belongs nevertheless to another construction type than the one described in this report but uses similar construction methods. Martin Wagner had had an innovative concept of the construction enterprise,where the workers free of making decisions: the “Bauhtte”. For details see “Weisse Vernunft” (1999).

Additional comments section 3: None


4. Socio-Economic Issues

Patterns of occupancy: The type of occupancy is generally residential. The number of inhabitants in a unit varies depending on the size of the units. There are units that can accommodate 2 (32-34 m²) to 8 (60-78 m²) persons. The size of the units, on the other hand, is determined by the degree of “luxury”. The most common unit is designed for a family of 3 to 5 persons (see figure 14). Each building typically has 24 housing units.

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

Number of inhabitants in a typical building of this construction type during the evening/night: Other

Additional comments on number of inhabitants: The average number of inhabitants in a typical building depends on the number of units. Approximately 96 inhabitants reside in a typical building.

Economic level of inhabitants: Low-income class (poor)

Additional comments on economic level of inhabitants: This construction type was considered as social housing for poor inhabitants based on the minimum living space principle of the Modern Movement. The rent was about 150-500 RM per month.

Economic Level: For Poor Class the ratio of Housing Unit Price to their Annual Income is 11:1.

Typical Source of Financing: Government-owned housing, Other

Additional comments on financing: After 1918 the state took the initiative to support housing construction in mainly two ways: cheap credits to private persons and financing of housing construction from public money, through the so-called [Wohnungsbaugesellschaften] = “Housing construction societies”. A corresponding legislative framework and different instruments (taxes and housing construction support programs about how to distribute these taxes) had been created. This replaced the “free housing market”. Before World War I (WWI), 25% of construction price was provided by the investor, 60% by the first mortgage (=credit got by the investor) and the rest by the second mortgage(this followed an English model concerning the separation between capital and interest). After WWI, problems were encountered with the second mortgage. This model is still implemented in the Dammerstock Siedlung in Karlsruhe.The mortgage is just 35% but there is an interest aid spanning over 12 years. In Frankfurt 40% of the cost is coveredby the so-called [Hauszinssteuer] = “House interest tax” and 20% comes from the Wohnungsbaugesellschaft. TheKarlsruher financing model is thus more independent from state money. Research societies were also financing innovative residential buildings. For further details see “Weisse Vernunft” (1999): [Wohnungsnot/Sozialpolitik](=“Housing shortage/Social politics”) and [Finanzierung] (=Financing).

Type of Ownership: Rent

Additional comments on ownership: The rent of the units in this construction type had gone down (up to 25% less) because of the newer buildings constructed with other techniques.

Is earthquake insurance for this construction type typically available?: Yes

What does earthquake insurance typically cover/cost: No data

Are premium discounts or higher coverages available for seismically strengthened buildings or new buildings built to incorporate seismically resistant features?: Not provided

Additional comments on premium discounts: Research to assess seismic risk for buildings in Germany is running and the aspects about insurance necessity are included in this research. According to this, some of the damages from the earthquake in 1978were covered by insurance. However, earthquake insurance is separated from house insurance. More details (in German) about insurance for “elementary damages” (this is, damages caused by natural forces) can be found at:http://www.diw.de/deutsch/produkte/publikationen/wochenberichte/docs/02-35-2.html#HDR2.

Additional comments section 4: None


5. Earthquakes

Past Earthquakes in the country which affected buildings of this type

Year Earthquake Epicenter Richter Magnitude Maximum Intensity
1970 Albstadt, Swabian Jura VIII
1977 Sigmaringen 3.8
1978 Tailfingen-Onstmettingen (Albstadt) 5.3 VII-VIII
1980 Onstmettingen (Albstadt, Swabian Jura) 3.5

Past Earthquakes

Damage patterns observed in past earthquakes for this construction type: For further details on the earthquake in 1978 see: http://www.iaag.geo.unimuenchen.de/sammlung/Zollerngraben.html The following earthquakes affecting Germany are documented in Ambraseys et al. (2002): 1977 - Albstadt, Swabian Jura (Magnitude 3.2 Ms); 1982 - Abstadt, Swabina Jura (Magnitude3.5 ML); 1983 - Grosselfingen (in Zollernalbkreis in front of the Swabian Alb; Magnitude 3.6 ML); 1992Wutschingen (north of the Rhein and south of Donaueschingen, west from Boden see in the Black Forest;earthquakes from there registered in Basel, Zrich and many other locations with both rock and stiff soil; Magnitude3.9 ML); 1996 - Gottmadingen (close to Wutschingen, west from Bodensee, between Singen and Zrich; 3.1 ML);1997 - Binzen (locality laying at the frontier between Germany, France and Switzerland; earthquake registered in Basel;3.1 ML); 1998 - Degerfelden (part of Rheinfelden, in the extreme SW Black Forest, next to the Swiss frontier; 2.6 ML);2000 - Steisslingen (near Singen next to Konstanz; 3 ML). See also: http://www.iaag.geo.unimuenchen.de/sammlung/Stockach.html for more recent earthquake activity. Historically on the 18th of October 1356the biggest earthquake of middle Europe destroyed the city of Basel. 1869/71 a strong earthquake in Gro-Gerau(north of Basel on the Rhein) followed. A new earthquake map for Baden-Wrttemberg has been proposed on:http://www.lgrb.uni-freiburg.de/d/akt/lgrb_n0202.pdf Damages caused by earthquakes among other “elementarynatural forces” in south-west Germany (Albstadt) are documented in the dissertation of Plapp(2003) and availableonline (in German) as follows: http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2003/wiwi/10&search=erdbeben&format=1&page=262 Thus the earthquake of 22 January 1970 in Zollerngraben (MMI = VIII) caused a total loss of 1 Million as a result of the damage. The earthquake of 18September 1977 in Sigmaringen (M=3.8) caused only low damage in buildings. During the earthquake of 3 September1978, 5000 buildings were damaged, 60 of them collapsed. 20000 people were affected, 23 injured, 100 left homeless,300 homes were evacuated. The total loss was 275 Million DM, of which 120 Million DM was insured. In the earthquake of 21 April 1980 only the phone connection in Albstadt was damaged. Damages caused by earthquakes among other “elementary natural forces” on the lower Rhein in Germany (Cologne) are documented in the dissertation of Plapp (2003) and available online (in German) as follows: http://www.ubka.uni-karlsruhe.de/cgibin/psview?document=2003/wiwi/10&search=erdbeben&format=1&page=258 - on the 13th of April 1992 anearthquake of M 5.2, max. Intensity VII-VIII occurred with epicenter in Roermond, the Netherlands. In Cologne,houses and vehicles were damaged. The main damage area was in the Netherlands but it was felt in Cologne as well.

Additional comments on earthquake damage patterns: Curvature up to 5cm of the floor; the out of plane deformation of reinforcing iron (30cm).


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.

Structural/Architectural Feature Statement Seismic Resistance
Lateral load path The 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. TRUE
Building Configuration-Vertical The building is regular with regards to the elevation. (Specify in 5.4.1) TRUE
Building Configuration-Horizontal The building is regular with regards to the plan. (Specify in 5.4.2) TRUE
Roof Construction The 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. TRUE
Floor Construction The 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 Performance There is no evidence of excessive foundation movement (e.g. settlement) that would affect the integrity or performance of the structure in an earthquake. FALSE
Wall and Frame Structures-Redundancy The number of lines of walls or frames in each principal direction is greater than or equal to 2. TRUE
Wall Proportions Height-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); N/A
Foundation-Wall Connection Vertical load-bearing elements (columns, walls) are attached to the foundations; concrete columns and walls are doweled into the foundation. TRUE
Wall-Roof Connections Exterior walls are anchored for out-of-plane seismic effects at each diaphragm level with metal anchors or straps. N/A
Wall Openings The total width of door and window openings in a wall is: 1) for brick masonry construction in cement mortar : less than ½ of the distance between the adjacent cross walls; 2) for adobe masonry, stone masonry and brick masonry in mud mortar: less than 1/3 of the distance between the adjacent cross walls; 3) for precast concrete wall structures: less than 3/4 of the length of a perimeter wall. N/A
Quality of Building Materials Quality of building materials is considered to be adequate per the requirements of national codes and standards (an estimate). FALSE
Quality of Workmanship Quality of workmanship (based on visual inspection of a few typical buildings) is considered to be good (per local construction standards). FALSE
Maintenance Buildings 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: Not provided

Vertical irregularities typically found in this construction type: Not provided

Horizontal irregularities typically found in this construction type: None

Seismic deficiency in walls: hollow bricks, large window openings

Earthquake-resilient features in walls: fills the frame

Seismic deficiency in frames: especially the column bases oxydates, as it lays without protection in the concrete

Earthquake-resilient features in frame: presence of stiffening elements

Seismic deficiency in roof and floors: heavier than computed and thus inducing additional loads into the structure; sensitive to oscillation

Earthquake resilient features in roof and floors: rigidity through large concrete volume or reinforcement

Seismic deficiency in foundation: Not provided

Earthquake-resilient features in foundation: Not provided


Seismic Vulnerability Rating

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

High vulnerability Medium vulnerability Low vulnerability
A B C D E F
Seismic vulnerability class < 0 >

Additional comments section 5: None


6. Retrofit Information

Description of Seismic Strengthening Provisions

Type of intervention Structural Deficiency Seismic Strengthening
Retrofit (Strengthening) The structure is heavier than designed one, which imposes additional loads to the structure; sensible to oscillation Replacement of damaged floors with new ones; reducing gravitational load at terraces(strengthening through replacement of thermal insulation material with a lighter one)

Additional comments on seismic strengthening provisions: These measures were applied because of general structural system problems, not necessarily due to seismic deficiencies.

Has seismic strengthening described in the above table been performed? It was performed in practice, in Stuttgart, see Ngele (1992), P. 112-114.

Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages? The building was damaged but not by an earthquake.

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 German government contracted the work. A workgroup was created including representatives from the finance and construction ministries, the direction of monuments of the state and of the city of Stuttgart, the Association of the Friends of the Siedlung. They had to determine the way of approach and a concrete rehabilitation concept. In the first phase the state of the siedlung in 1927 was documented. In a second phase a building survey was conducted. In the third phase the rehabilitation concept was developed. This included the construction technique, the infrastructure technique, the concept for implementation with the tenants, costs estimation, application for financial means and detailed plans for monument conservation. Architects were involved; they had to identify themselves with the role of the “protector of a cultural monument”.

What has been the performance of retrofitted buildings of this type in subsequent earthquakes? No data is available on this.

Additional comments section 6: None


7. References

  • Typical Constructions from 1860 till 1960/ Vol. I. Foundations, Isolations, load bearing massive walls,corniches, smokestacks, load bearing walls out of wood, old units of measure (in German)Ahnert,R., and Krause,K.H.CD-ROM; ISBN 3-345-00622-7 2000
  • Typical Constructions from 1860 till 1960/ Vol. II. Wooden joist floors, massive floors, floor index,floorings, bays and balconies, overview of live loads (in German)Ahnert,R. and Krause,K.H.CD-ROM, ISBN 3-345-00623-5 2001
  • Typical Constructions from 1860 till 1960/ Vol. III. Beams and masonry belt arches, piers and columns, stairs,roofs and roof structures, wooden roof buildings, loading assumptions for the roof (in German)Ahnert,R. and Krause,K.H.CD-ROM, ISBN 3-345-00624-3 2002
  • Internet-Site for European Strong-Motion Data, European Commission, Research-Directorate GeneralAmbraseys,N., Smit P., Sigbjornsson,R., and Suhadolc,P., and Margaris,B.Environment and Climate Programme. Geo. - Hamburg : Gruner + Jahr ISSN 0342-8311, 1980 2002
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Authors

Name Title Affiliation Location Email
Maria D. Bostenaru researcher Urban and Landscape Design Department, Ion Mincu University of Architecture and Urbanism str. Academiei nr. 18-20, Bucharest 010014, ROMANIA Maria.Bostenaru-Dan@alumni.uni-karlsruhe.de

Reviewers

Name Title Affiliation Location Email
Ahmet Yakut Assistant Professor Department of Civil Engineering, Middle East Technical University Ankara 6531, TURKEY ayakut@ce.metu.edu.tr
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