Mainau Inseleingang, Entrance to isle of Mainau
General information
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Home page
http://www.bfl-tr.com
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Location address
D-78465 Insel Mainauemail: info@mainau.de
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Location country
Germany
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Name of the client/building owner
Mainau Gmbh
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Function of building
Public spaces
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Degree of enclosure
Open structure
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Climatic zone
Temperate - cold winters and mild summers
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Number of layers
multi-layer
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Primary function of the tensile structure
- Rain protection
Description
As is typical for this type of structure, architect and specialist engineer worked together in order to develop a convincing solution. Both described the process of designing the structure as an iterative process between the disciplines. The structure is a widespaned irregular shaped ridge with landmark character.Three very slender ridge arches with radial cable suspensions (spoke wheel principle) are stabilized by the membrane. Each arch is supported on beam bearings on top of a tripod at one end and an A-shaped trestle at the other end. The prestressed membrane gets the necessary curvature by two valley cables and circumferential border cables. Ten beams with, in each case two cables stretching the roof. The border cables themselves are fixed to the arches and masts. The overall structure is deflective due to its absolute lightweight approach.One of the requirements to the material was very high translucency. For this reason glass fibre fabric laminated with PTFE foils on both sides was chosen. Due to the open mesh weave (mesh size 1 mm x 1 mm), the material provides a higher translucency than standard PTFE-coated glass fibre fabrics. However, welding of the fabric requires a certain experience because the PTFE-foils tend to delaminate from the weave. Büro für leichtbau Tritthardt + Ayrle in cooperation with the supplier of the material modified the manufacturing process of the material. In the interaction with the high quality welding technology of Ceno Tec a high resistance seam was the result. Consequently, a number of welding seam and edge detail tests were carried out prior to fabrication in order to find out the correct welding parameters. Furthermore, testing during production was required for the authorities approval (single case approval). Standard PTFE-coated glass fibre material was used for reinforcements, edge cable pockets and other membrane details. The membrane was provided with draining rails in order to lead rainwater to the lower membrane corners, where it is collected in steel funnels underneath the membrane. The drainage rails made from PTFE-coated glass fibre fabric are welded to the membrane. With a structural steel work of only 18 kg/m2 (from top of foundations) the structure is a real lightweight structure. The membrane was fabricated in 3 panels. All secondary steel components and cables were installed on the ground before lifting the membrane. The membrane was carefully lifted by using a webbing belt net in order to avoid sharp kinking. The installation of the structure was completed in approximately two weeks.
Description of the environmental conditions
The « Insel Mainau » is a well-known holiday resort at the lake « Bodensee» in south west Germany.The island of Mainau in the Bodensee (Lake Constance) is known as the Flower Island. A special microclimate allows growth of subtropical plants on the island. Owned by the Earl Lennart Bernadotte Foundation and the Earl's family, Mainau is today one of the major touristic attraction in the Bodensee region.
Material of the cover
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Cable-net/Fabric/Hybrid/Foil
Fabric
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Type (code)
Fiberflon 04838/140
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Material Fabric/Foil
Glasfabric
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Material coating
PTFE
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Weight (g/m2)
665
Main dimensions and form
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Covered surface (m2)
1350
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Maximum height (m)
11
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Total length (m)
56
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Total width (m)
40
Duration of use
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Temporary or permanent structure
Permanent
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Design lifespan in years
31-..
Involved companies
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Architects
bmt architects with büro für leichtbau
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Engineers
büro für leichtbau
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Contractors
Ceno Membrane Technology GmbH
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Suppliers
Ceno Membrane Technology GmbH
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Other companies
Tobler Stahlbau AG
Editor
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Editor
Jörg Tritthardt
