Hyperbolic paraboloid shell

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Hyperbolic paraboloid with parabolas (black) and straight lines (red, blue). In the case of horizontal cuts, hyperbolas occur (not shown).

The hyperbolic paraboloid , and HP-shell ( Herbert Müller ) or Hyparschale ( Ulrich Müther called), is a special form in the modern roofing . It is a regularly double-curved surface that contains hyperbolas and parabolas as well as straight lines. This shell shape is also called the " saddle surface " and should not be confused with a conventional saddle roof . A paraboloid (= saddle surface) has only hyperbolic surface points and thus the Gaussian curvature is negative ( ). Steel cables are used as the building material for the supporting structure , as this is the only way to create the necessary tensile forces in large buildings. A wide variety of materials are used for the roofing .

history

In 1928 the engineer Tatjana M. Markowa registered a Soviet patent for roofs whose geometry followed the rules of the hyperbolic paraboloid.

The first shell structure made of reinforced concrete in the form of a hyperbolic paraboloid was developed and realized by Fernand Aimond (1902–1984) in the 1930s. Aimond developed a theory of the HP shell as early as 1932 and, from 1934 to 1939, designed several HP shells made of reinforced concrete for aircraft hangars and workshop roofs for airfields. In addition to Aimond, other pioneers are Giorgio Baroni, Konrád Hruban (1893–1977), Félix Candela and Herbert Müller .

Roof structures

In modern architecture, the hyperbolic paraboloid is used almost entirely as a roof structure. A (round or angular) surface is curved symmetrically downwards from two opposite low points, while two high points curve this curved surface upwards in opposite directions. Hypar shells can be shuttered with straight boards because their double-curved surfaces are created from straight lines.

With this type of roof, the roof load ( ridge and rafters) is no longer borne by the walls, here the load can also be borne by the shell itself - the roof is self-supporting with prestressed concrete cables. It is also called a shell structure. If the two lowest points are clamped together by a steel cable below the structure, the roof is even more stable. The rainwater no longer flows off in an eaves , but collects at the lowest points of the roof.

A construction technique that was frequently used was the use of prefabricated, square concrete segments that were hung in the grids that formed the rope nets. Then the roof ceiling was shuttered underneath and then the roof was concreted. This process made the respective roof more stable, but also heavier and more expensive compared to other roof coverings such as steel.

Another construction technique, the dry spraying process, uses a shotcrete machine to apply concrete with compressed air to the reinforcing steel , a wire mesh and its casing underneath. Internally, this process is also known as Torkretizing (after the Essen company Torkret ), which was patented by Carl Weber in 1919. The advantage of this method lies in the lower concrete consumption and the thinner roofs.

In 1969/70 Ulrich Müther developed the wet spraying process for the Oberhof luge track with close-meshed wire mesh on both sides of the reinforcing steel, which also enabled shotcrete to be poured without formwork.

Building types

Several types of construction can be distinguished in the area of ​​HP shells . The roofs are mainly rectangular, like those on Ulrich Müther's buildings , such as the Ostseeperle restaurant in Glowe (1968) or the Hyparschale in Magdeburg (1969). In West Germany, for example, there are the Friedrich-Ebert-Halle in Ludwigshafen am Rhein (1962–65), the St. Hildegard Church in Limburg an der Lahn (1965–67) and the Alsterschwimmhalle in Hamburg .

On buildings with round roofs made of HP shells, the Dorton Arena is the first to be mentioned in the building history , the roof of which consists of a steel cable network, which in turn is hung and supported on two semicircular prestressed concrete girders. Further examples are the Congress Hall (Berlin) , the Teepott in Rostock and the Ice Aréna in Prešov .

Herbert Müller worked with long prefabricated reinforced concrete parts made of half-tubes that were only very slightly curved in the longitudinal direction. He put these half-tubes next to each other so that his roofs formed a wave shape. In contrast to flat reinforced concrete girders, the strong vertical and slight horizontal curvature results in a higher bending and bending stiffness and therefore requires less material. Müller was able to equip many special buildings in the GDR such as the pavilion on Petersberg near Halle . A rare use of Müller's only slightly double-curved precast concrete elements was a 45-meter-long pedestrian bridge ("Blue Bridge") in Halle (Saale) near Riebeckplatz (1971), the bridge part of which was supported by three half-tubes made of prestressed concrete . The city building authority decided against renovating the porous concrete ceiling and tore down the bridge on October 5, 2017.

The indoor swimming pool Faulerbad   in Freiburg im Breisgau has ten hyperbolic parabolic shells with a roof made of wood. The Freiburg architect Hans-Dieter Hecker used steel girders as a frame for the roof structure, covered with three rows of wooden ceilings as kite-shaped squares that are supported on reinforced concrete columns and held in place with prestressing steel. The swimming pool received the Hugo Häring Prize in 1984 .


literature

- Alphabetical -

Web links

Commons : Hyperbolic roofs  - collection of images, videos and audio files

Individual evidence

  1. ^ Karl-Eugen Kurrer : History of structural engineering. In search of balance. 2nd, greatly expanded edition. John Wiley & Sons , Berlin 2016, ISBN 978-3-433-03134-6 , reference .
  2. ↑ Anke Zalivako: The Buildings of Russian Constructivism Moscow 1919–32. Building materials - building construction - preservation (=  Johannes Cramer and Dorothée Sack [Hrsg.]: Berlin contributions to building research and monument preservation . Volume 9 ). Michael Imhof Verlag, Petersberg 2012, ISBN 978-3-86568-716-6 , p. 326 .
  3. ↑ Bernard Espion: Pioneering hypar thin shell concrete roofs in the 1930s . In: Concrete and reinforced concrete construction . 111th year, no. 3 . Ernst & Sohn, Berlin 2016, p. 159-165 .
  4. ^ Jürgen Joedicke : Shell construction. Construction and design. Karl-Krämer-Verlag, Stuttgart 1962, p. 11 .
  5. ^ Jürgen Joedicke: Shell construction. Construction and design , [ Shell architecture ], Reinhold, Stuttgart 1963, p. 27 .
  6. ↑ Picture from the roof of the after-work house Knapsack : The network of steel cables as a saddle-shaped roof surface. ( Memento of March 6, 2019 in the Internet Archive ). In: gkkg1935.de .
  7. ↑ Picture from the roof of the after-work house Knapsack: Prefabricated concrete segments are hung into the suspended roof. ( Memento of March 6, 2019 in the Internet Archive ). In: gkkg1935.de , and as a slide show.
  8. ↑ cf. on roofing with steel, Ursulina Schüler-Witte : The congress hall in the zoo - reconstruction of the roof 1980–1987. In: Ralf Schüler and Ursulina Schüler-Witte: A work-oriented biography of the architects of the ICC. Lukas Verlag , Berlin 2015, ISBN 978-3-86732-212-6 , pp. 187-191.
  9. ^ Karl Drebenstedt: Excursus on shell construction history. In: TU Cottbus , May 13, 2011.
  10. ↑ Tanja Seeböck: Ulrich Müthers shell buildings in the building industry of the GDR. In: Germany Archive , ed. from Federal Agency for Political Education (bpb), Bielefeld, 45 (2012), 4, pp. 694–702, chap. V.
  11. ↑ Christoph Gunßer: 1962-65. Friedrich-Ebert-Halle in Ludwigshafen. In: db deutsche bauzeitung , August 2, 2015, No. 5.
  12. ↑ History of the Petersberg Pavilion. In: pavillon-petersberg.de , accessed on September 9, 2016.
  13. ↑ Enrico Seppelt: Blue Bridge: traffic lights over Merseburger Straße should come. In: hallespektrum.de , January 28, 2013, accessed on October 4, 2016.
      Photo series: Pedestrian bridge on Riebeckplatz. In: mapio.net , accessed on October 4, 2016.     Photo
      series: Blue Bridge. In: halle-im-bild.de , March 31, 2015, accessed October 4, 2016.
  14. ↑ Detlef Färber: "Blue Wonder". Pedestrian bridge at the train station will be demolished next summer. ( Memento from July 28, 2016 in the Internet Archive ). In: Mitteldeutsche Zeitung , July 25, 2016.
  15. ↑ Oliver Müller-Lorey: Landmarks and torment. Blue miracle in Halle will be torn down from today. In: Mitteldeutsche Zeitung , October 5, 2017.
    Photo gallery: Demolition of the blue bridge at Riebeckplatz. In: hallelife.de , October 2017.
  16. ↑ Faulerbad. In: badeninfreiburg.de , with photo series .
  17. ^ Andrew Orton: Faulerbad, Freiburg, West Germany. In: ders., The Way We Build Now: Form, Scale and Technique. Taylor & Francis, London, revised new edition, 2016, ISBN 978-1-138-17522-8 , pp. 428–431, limited preview in Google Book search.
  18. ↑ Lexicon entry: Hans-Dieter Hecker - architect. In: archInform.net , accessed on June 2, 2020.