• Canopy for exit of customer center of Autostadt in Wolfsburg
    © Tobias Hein
Projects

Canopy for exit of customer center of Autostadt in Wolfsburg

Wolfsburg, Germany, 2013

The exit of the customer center provides a space for drivers to try out the electronic systems of new car models. The design for the roof is based on the idea of a ‚leaf in the landscape‘. It is composed of a saddle surface with only two minimalist support points on the ground, which integrates itself lightly and harmoniously into its surroundings. The support structure has an elliptical footprint and spans a length of 55 m and a width of 38 m. The global saddle geometry creates two peaks and two valleys, with the highest points approximately 6 m and 9 m higher than the lowest points. The saddle surface consists of a cable net supported PTFE-membrane, with a dynamically shaped hollow section edge beam made of doubly curved structural steel profiles along its perimeter. The membrane and cable net planes are both held in tension by the compression ring edge beam and are interconnected at the nodes of the cable net.


  • Location

    Wolfsburg, Germany

  • Architect

    GRAFT, Berlin; WES LandschaftsArchitektur, Hamburg

  • Cooperation

    Kardorff Ingenieure Lichtplanung GmbH, Berlin

  • Awards

    Ingenieurpreis des Deutschen Stahlbaues 2015

  • Client

    Autostadt GmbH

  • Contractor

    Eiffel (Stahlbau/steel construction); Taiyo, formTL (Membrane)

  • Our Scope of Work

    conceptual design, construction design, technical spots check

Strain

If there is an external load acting perpendicular to the surface (like wind pressure or suction) the equilibrium state of planar nets,such as vertical or inclined cable net facades, can only be reached through elastic elongation. These strains can be "anticipated" and thus reduced by pretension because the equilibrium state is reached at an earlier point of deformation. Still, there will be increasing deformations towards the center of the net.

 

Membrane and cable net do not only follow the same anticlastic shape. They are also both similar in set-up and load-bearing behavior since their layers are made out of tension members which are woven or rather knotted in an orthogonal alignment towards each other (compare suspension/tension ropes with warp and weft directions).

 

This factor carries a certain advantage: Since the offcut of the membrane is generally defined by its orientation within the structure's final shape, it can be minimalized as long as the seam layout follows the orthogonal cable lines, which was wanted in any case.

How can 150 tons appear light?

The roof, a membrane-covered, self-anchored cable net with a dead load of only 8.3 kg/m² covers an area of 1610 m². The edge beam has a total length of approximately 150 m and is symmetrical to the longitudinal axis of the oval layout. The section consists of a welded pentagonal steel box (S355) which undulates and rotates along the longitudinal axis of the edge beam. Thereby the sheet dimensions vary continuously and cause a light and dynamic appearance despite weighing 150 t in total.

 

The cable net consists of two series of open spiral cables that are aligned orthogonally towards each other with a total cable length about 2100 m. For structural reasons the diameter of the concave-oriented suspension cables (24 mm) varies from the tension cables (20 mm). 

 

It was a guiding principle of Graft and schlaich bergermann partner during the interactive design process to keep the complex structure plain and simple by means of structural clarity in concept and detail.

Main characteristic features of the structure are the plainly visible cable net and the dynamic shape of the edge beam carried by two supports only.

  • Membrane area 1,610 m²
  • Width 38 m
  • Cables open coil ropes, galvanized,
    Ø 20 mm, 24 mm, length 2,000 m
  • Foundation pile foundation, Ø 60 cm, length 20 m
  • Length approx. 55 m
  • Height max. 9 m
  • Membrane PTFE coated glass fiber membrane,
    Type 3
  • Canopy for exit of customer center of Autostadt in Wolfsburg © Tobias Hein
  • Canopy for exit of customer center of Autostadt in Wolfsburg © Tobias Hein

Project location

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