Textile construction

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Textile building (also: textile architecture , membrane construction ) refers to building with membranes and ropes . Membranes are flat components that are pliable and are only subjected to tensile loads, such as B. uncoated and coated fabrics , knitted fabrics , scrims as well as foils and fiber-reinforced foils. Ropes are understood to be flexible, linear components such as braided, twisted and woven wires and threads that are only subjected to tensile loads.

The term textile architecture is also used for tent constructions such as yurt , jaranga ( Chukchi 'house'), tipi , camping tent, circus construction , wigwam and wickiup . Gottfried Semper was considered one of the most important connoisseurs of textile architecture since prehistory . The architect Frei Otto is considered the father of modern membrane architecture .

application

Textile structures are used in the area of football stadiums , traffic structures, roofs on shopping streets or exhibition halls. Examples include the transparent roofing of the Lower Saxony Stadium in Hanover ( HDI-Arena ) or the roofing of sports facilities for the 2008 Olympic Games in Beijing, as well as the Allianz Arena and Soccer City .

There are two main forms of textile architecture: as free-standing constructions, e.g. B. a warehouse or a large parasol, or in connection with conventional architecture, e.g. B. A canopy that has been added to and connected to a building.

draft

The process of developing a project is as follows:

The architect's sketch of the functional requirements of the roofing or the visual effect defines the basis of the project.
The fabricator in the form of the membrane construction company creates a preliminary draft from the architect's sketch, which contains both the geometrically necessary shape and the necessary structural elements, such as the positioning of supports, bracing, anchoring, etc.
Based on the design of the membrane company, the final design is compared with the architect and the client, including the planned aesthetics and functional requirements.

burden

With textile roofs, the final shape is only determined by the statics. Due to the long service life of the materials, textile buildings are now classified as permanent buildings just like conventional buildings. Depending on the standard of the individual country, they are subject to approval and must comply with the load assumptions contained in the respective building regulations. Regional requirements regarding wind and snow loads must be taken into account as well as specific climatic conditions.

The complete requirement profile of the textile roof results from the statics of the membrane. This is where the edge geometry and the edge design, serving the load transfer, are determined. The same applies to load application points in the structure . In addition, it must be ensured that the textile roofing changes shape in the event of external loads, such as wind or snow. These changes in shape have to be absorbed by connection points on existing conventional structures or by introduction of forces into foundations.

The weight of the material (around 1.0–1.5 kg / m ² ) can be neglected here, in contrast to traditional buildings. The resulting high susceptibility to wind loads can be compensated for by shaping and prestressing the static equilibrium. However, there are special demands on the structure and foundations related to the load introduction . The load-bearing capacity of the subsoil is only decisive for the dimensioning of the foundations in a few exceptional cases. Depending on the soil conditions, tensile loads can be diverted using heavy-duty foundations or special ground anchors.

engineering

The necessary tensile strength of the material is defined from the static calculation. A combination of steel construction and ropes is usually chosen as the supporting structure. The design can be freely selected as long as the geometric and construction-related connection points are taken into account. Due to the lightness of the roofing, it is advisable, for example, to break up supports and carrier systems into filigree lattice structures or to replace them as far as possible with rope structures. Of course, supporting structures made of aluminum, stainless steel, glued wood constructions, glass, Plexiglas or reinforced concrete are also conceivable. As membrane materials that are suitable for outdoors, z. B. polyester, acrylic or PVC. In order to achieve the desired properties for textile architecture, such as flame resistance, resistance to light and water, etc., the membranes are coated, e.g. B. with PTFE (Teflon).

After approval of the static calculation by the building authority, the construction drawings are created. Especially with regard to the design elements, they have to be agreed with the planner and client. It is important that, in addition to the accurate geometry for the membrane, sufficient attachment points for assembly and clamping tools are provided. In general, the supporting structure and the membrane are prepared completely ready for assembly in the factory, similar to a prefabricated house.

Manufacturing

The time required from the first idea to implementation is six to nine months. Simple structures can be implemented more quickly, more complex designs, such as a stadium roof, can take up to fifteen months. The planning phase from the idea to the approval planning normally takes two to three months. After approval, around one to two months are required for the work planning and then, depending on the scope of the project, up to six months for production in the factory. The actual production on site is comparable to the erection of a prefabricated house. The foundations are created by the customer in parallel to the factory production. For example, one to two weeks should be planned for the assembly of an area of around 500 m ² .

In planning, after the idea has been concretized, the draft planning begins, which consists of finding the form in connection with a rough static calculation. The design is to be compared with the functional and aesthetic requirements on site. Then the final planning begins, which ends with a verifiable static calculation. After a successful check of the statics by an auditor, the execution plans are created, which must also be checked. After final approval and approval, the workshop plans are produced and the structure, cables and membranes are cut, as well as assembly planning.

There are some special features in the manufacture of a textile roof. The supporting structure, for example made of steel, can hardly be distinguished from conventional steel structures. However, minimum tolerances must be implemented here. In areas where the connection geometry is important, the locksmith takes on the function of a precision mechanic.

For the membranes, after the final geometry has been determined, with the help of special three-dimensional computer programs, a cut-to-size model is developed that reflects the planned state of pre-tension, taking into account the expansion behavior of the selected material. The resulting individual blanks are applied computer-assisted to the raw material delivered in rolls, taking seam allowances into account, or cut out directly with special CNC cutting plotters. The resulting cutting tracks are then welded to one another by high-frequency welding machines or thermally.

Assembly

The membrane is delivered to the construction site after the steel structure has essentially been erected. Separate process concepts are developed for assembly, some of which contain static assembly status calculations using load cases in sub-steps of assembly. Installation takes only a few days or weeks, depending on the project, which is a great advantage for the construction site itself. All other work there can be carried out largely unhindered. Depending on the local situation, it can make sense to erect the textile roof right from the start. This sometimes enables weather-protected continued work under this roof, but requires that precautions are taken against the destruction or damage of the membrane or damage to the tensioning cables by construction vehicles and cranes. If this membrane is only built at the end of a measure, it must be checked beforehand to what extent planned installations may make this project impossible. Installation after completion of the construction work is always recommended if, due to strong dust formation, e.g. B. during earthworks, the membrane is too dirty and has to be cleaned.

maintenance

Textile roofs are made in such a way that they are largely maintenance-free for the planned service life. The re-tensioning that was common at the beginning of this construction method in the early 1970s is no longer necessary with the materials and technologies used today. The membrane itself does not corrode or weather. Maintenance consists solely of regular checks of the visual appearance.

Care and cleaning

A textile roof needs cleaning every now and then. The modern surface protection coatings used today (e.g. PVDF paint) or the glass or PTFE material are predominantly self-cleaning due to the homogeneous surface. A patina, comparable to the soiling of a pane of glass, naturally cannot be prevented. The cleaning of membrane surfaces is subject to special requirements. The membrane construction also requires regular visual inspection for external mechanical damage (storm, etc.).

material testing

The various material tests are carried out according to the standards of the respective countries. For example, in addition to maximum tensile forces, maximum tensile force elongation, tear propagation force values, adhesion values between coating and fabrics, chemical resistance and flame resistance are also tested. Depending on the use and type of membrane, extensive tests are necessary, which require scientific and technically specialized laboratories and testing facilities.

Guarantee

The young construction method of textile construction has been established in many thousands of buildings around the world for more than 25 years. The minimum life expectancy of such structures, provided they are carried out professionally, is 10 to 20 years , depending on the material and weather conditions . In the case of glass or PTFE constructions, more than 25 years can be expected. It is now quite common to agree to the standard warranty framework of two or even five years for conventional buildings. Longer, graduated and function-related grant periods are usually given in connection with a maintenance contract, so they must be taken into account in the price.

literature

Sylvie Krüger (editor): Textile architecture ; Jovis, Berlin 2009. ISBN 978-3-86859-017-3 .
Markus Heinsdorff: "Mobile Spaces - Textile Buildings", JOVIS Verlag Berlin 2014, ISBN 978-3-86859-295-5
Melanie Schmidt: "Membrane in Architecture", Technical University of Munich, PDF

Web links

Computer Programs: Formfinder and Dlubal

Website of the TEXTILE-ARCHITECTURE network

Individual evidence

↑ Rosemarie Wagner: Building with ropes and membranes . Beuth Verlag, Berlin Vienna Zurich 2016, ISBN 978-3-410-21719-0 , p. 1.
^ Terhi Kristiina Kuusisto: Textile in Architecture. Master's thesis, Tampere University of Technology, first introductory sentence.
↑ G. Semper : The four elements of architecture. (PDF 15.9 MB). Braunschweig 1851;
The Four Elements of Architecture and other writings. Cambridge University Press, England 1989.
↑ Klaus-Michael Koch: Renaissance in building with membranes, in: Petra Knecht (Ed.): Technical textiles . German specialist publisher. Frankfurt am Main 2006, ISBN 3-87150-892-6 ; P. 177.

[1] Rosemarie Wagner: Building with ropes and membranes . Beuth Verlag, Berlin Vienna Zurich 2016, ISBN 978-3-410-21719-0 , p. 1.

[2] Terhi Kristiina Kuusisto: Textile in Architecture. Master's thesis, Tampere University of Technology, first introductory sentence.

[3] G. Semper : The four elements of architecture. (PDF 15.9 MB). Braunschweig 1851;
The Four Elements of Architecture and other writings. Cambridge University Press, England 1989.

[4] Klaus-Michael Koch: Renaissance in building with membranes, in: Petra Knecht (Ed.): Technical textiles . German specialist publisher. Frankfurt am Main 2006, ISBN 3-87150-892-6 ; P. 177.