A THEMATIC NETWORK TO UPGRADE THE BUILT ENVIRONMENT IN EUROPE THROUGH TENSILE STRUCTURES

w w w . t e n s i n e t . c o m N E W S L E T T E R N R . 8 - M A R C H 2 0 0 5

Editorial Board:Mike Barnes, John Chilton, Mike Dencher, Brian Forster, Peter Gosling,Caroline Henrotay, MarcMalinowsky, Marijke Mollaert,Peter Pätzold, RudiScheuermann, Javier Tejera Coordination:Marijke Mollaert, phone: +32 2 629 28 45,marijke.mollaert@vub.ac.be

Address:Vrije Universiteit Brussel (VUB), Fac. of Applied Sciences, Dept. of Architecture, Pleinlaan 2, 1050 Brussels, fax: +32 2 629 28 41,http://wwwtw.vub.ac.be/ARCH/research/publications/showPublicationlist.asp

Tensi ews

Tensi ews Tensi et partners

2The ETFE roof of the AWD-Arena

The Berlin-Bad Wannsee Golf and Country Club

3Aesthetics and functionality:

The Antilles de Jonzac

4The Constructive Membrane

Building

6The Soccer Stadium Allianz Arena:

A pulsating ovalFluon® ETFE Foil to be used forthe Allianz-Arena Soccer StadiumThe Steel Beam Waterproofing

of the Allianz Arena

7TENSAIRITY® PROJECT Garage Park Montreux

8Forum of cultures,

Barcelona 2004

9Design Concept

10Academic Institutions:Politechnico di Milano

11Innovative building methods

of shell structuresHochschule Nürtingen,

Institute for Applied Research

12Experimental investigation of a conical shaped textile

membrane under snow loading

13Forthcoming EventsTextile Roofs 2005

14Structural Membranes 2005

13th Int. Techtextil Symposium

15Frei Otto

wins the Royal Gold Medal& Retrospective on his lifework

16IASS Symposium

Literature

Ceno Tecwww.ceno-tec.de

European Council for Construc-tion Research, Development andInnovation www.eccredi.org

Form TLwww.Form-TL.de

Hopkins Architectswww.hopkins.co.uk

Laboratorium Blum

Messe Frankfurt/Techtextilwww.techtextil.de

SL-Rasch GmbHwww.sl-rasch.de

Taconic Internationalwww.4taconic.com

The Arup Groupwww.arup.com

Universidad Poletécnicade Madrid www.aq.upm.es

technet GmbHwww.technet-gmbh.com

Tensotech Consultingwww.tensotech.com

Tentechwww.tentech.nl

University of Bathwww.bath.ac.uk/Departments/Arch

University of Lincolnwww.lincoln.ac.uk/architecture/arc/

University of Newcastlewww.staff.ncl.ac.uk/p.d.gosling/pdg/

Vrije Universiteit Brusselhttp://wwwtw.vub.ac.be/ARCH/research/publications/showPublicationlist.asp

W.L. Gore & Associateswww.gore.com/tenara

form TL

Canobbio S.p.A.www.canobbio.com

Dear Reader,

Now that EU funding for the establishment of TensiNet has concluded, it is appropriate to restate the objectives of theorganisation: essentially it is an industry sponsored network for the dissemination of information relating to TensileStructures, and prestressed fabric membranes in particular. This exchange of information is to be principally at aprofessional level between architects, consulting engineers, fabricators and manufacturers; but also at an educationallevel to support, through project precedent studies and CAD software for educational use, the growing number ofgraduate option and postgraduate courses in European universities. This dissemination should involve new ideas, newmaterials and potential applications, as well as information on built projects.

The membership of TensiNet is currently drawn from 26 countries worldwide, although in terms of numbers,predominantly from European countries. The website with its links to numerous companies of architects, engineers andfabricators is open to all users, but only members of TensiNet have access to the substantial and continuously updateddatabase concerning built projects. It is intended to expand this in future to include more information on both structuraland environmental design, as well as fabrication details. This will be principally at a level which is intended to supportthe various courses on the design of lightweight structures, but will also be of wider interest to professionals.

The publication of TensiNews is intended to reflect the aims of TensiNet; principally with summary reports on builtprojects and new developments in materials and applications. It is also intended to include in each issue a report onacademic (postgraduate) courses and the publication of the best examples of student design project work. Althoughpurely research articles are excluded, it is certainly intended to give due prominence to the results of research and itstake-up in new design applications. In that context it is hoped to provide a forum for discussion of possibilities for futureresearch directions and needs. Articles on projects or ideas are welcome.

Mike Barnes

Name of the project: New AWD-Arena in Hannover

Client: Niedersachsenstadion, Projekt- und Betreibergesellschaft GmbH,

Hannover

Architect: Schulitz + Partner,

Viewegstraße 26, 38102 Braunschweig, www.schulitz.de

Engineers: RFR Ingenieure GmbH,

Dürrheimer Straße 12, 70372 Stuttgart, www.rfr-stuttgart.de

Primary structure: steel

Steel contractor: ThyssenKrupp Stahlbau GmbH, Hannover

Membrane structure: ETFE-foil, single-layer, cable-supported

ETFE foil: covertex GmbH, Obing

Manufacturing: KfM GmbH, Edersleben

Prüfingenieur: Prof. Peil + Partner, Braunschweig

Wind Engineering: Prof. Sedlacek + Partner, Aachen,

Ing.-ges. Niemann + Partner, Bochum

Duration of installation: 2 months

Planning of execution: E + D, Dieter Linke

covertex GmbH, Stephan Brückner

Roof area: 10 000 m2

Thickness of foil: 250 µm

Area weight: 0.350g/m2

Light transmission: approx. 95 % (UV-A, UV-B transmission approx. 94 %)

Tensile strength: 52 N/mm2

Fire class: DIN 4102 B1, BS 476 class 0, NF P 92 M2

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The Berlin-Bad Wannsee Golf and Country Club

Name of the project The Berlin-Bad Wannsee Golf and Country Club

Architecture and construction management Atelier RATZ, Berlin

Design and engineering formTL, Radolfzell

Manufacture CenoTec Greven

Membrane Sattler Polyplan PVC coated polyester fabric Type 2

Inspector TÜV Süddeutschland

Size: linear setup with altogether 20 parts with a width of 2.4m

6m x 50m

Design, production and assembly 7 weeks

gerd.schmid@form-TL.de • www.form-TL.de © drawings: formTL - © pictures: Michael Fahrig / Golfclub Wannsee

The roof design of the newAWD-Arena in Hannover wasdeveloped by the architect H.Schulitz, Braunschweig and theengineers of RFR, Paris/Stuttgartin an international competitionthat was held in the year 2000.The design team searched for aneconomical, light and powerfulsolution that would fit into thecomplex geometric boundaryconditions. The asymmetricgeometry given by the underlyinghill and the separation of thestands into an outer and aninner part are still clearly visiblein the design of the roofstructure.

This leads to the characteristicsubdivision into an opaque anda transparent roof section. Instructural terms this gave theopportunity to cross the loadsupporting hangers with theroof surface and to create twodistinctive spoke-wheel systemswith a maximum overallstructural height. The outer 16 000 m2 roof section isbasically a conventional steelstructure with metal sheetdecking. The inner roof partcomprises the two primarytension rings and represents aquite flexible cable structure,which is completely covered with

11 000 m2 of clear single layeredETFE foil. The area to becovered with ETFE is dividedinto 34 oblique-angledrectangles with a size ofapprox.18m x 24m.

The choice for this material wasmade at an early design stage,at a time when ETFE was stillquite unpopular and only sparsereferences of small surfacescould be shown to the clientand the checking authorities toprove the feasibility of theconcept. But the architect wasable to convince the investorsand the further tenant to invest

another 10 millioneuro in orderto realize an elegant transparentroof and to ensure that thepitch would have best growthconditions. Later on, theconcept was confirmed by theyoung German manufacturercovertex that is specialised inETFE foil systems and came upwith a very neat andstraightforward proposal todesign a completely flat foilsurface. Initially, the design teamintended to create a doublecurved surface with a muchlighter substructure that wasbased on a complex and non-repetitive cutting pattern.

The ETFE roof of the new AWD-ArenaThe two primary tension rings The framework trusses

The Berlin-Bad Wannsee Golf and Country Club, founded in 1895, issituated at the south-west of Berlin, and with 1600 members it is oneof the largest and most famous golf clubs in Germany. The long-established 27-hole golf course is set idyllically in the mature woodedBrandenburg countryside and features a variety of gently rollingfairways. Roland Specker, known because of the "Wrapped Reichstag",is Chairman and a guarantor for an exclusive membership.

The building constructor EsmeryCaron Structures has built afitness centre, which is a large-scale textile building with a quiteappealing and sophisticatedarchitecture and unusualaesthetics.

The textile building is located inJonzac (near Royan, France) andwas completed in 2002. The Antilles de Jonzac has twocovered zones, a back zonewhich covers the public area ofthe centre, and a front zonecovering the administrativeservices.

Back zone The design of this covered zoneis as follows: alternating arcswith a simple curvature, andarcs with a double curvaturesupport the roof, all the arcshave different heights from 14mfor the zone called the“mushroom” area, up to 24mfor the highest arcs located overthe main entrance.

The covering of this zoneconsists of twenty-four differentmembrane panels for a totalsurface area of about 8 500 m2.The membrane used is a whitepolyester/PVC fabric, Type IV (1 350 g/m2) from Verseidag. It has been treated with a 100%PVDF finishing, and has an M2 fire rating. It is held up by38 boltrope cables withoutadjustment fittings.

Each membrane panel is madeup from an average of nineteenpieces, all different. The making-up consisted of the tracing pieceby piece, the scraping/scratchingof the assembly edges forsubsequent welding and the

High Frequency welding with awidth of 40 mm.

The water tightness between twofabric panels is ensured by twoadditional flaps, High Frequencywelded on the full fabric in theworkshop and attached one tothe other by thermal welding onsite.

The membrane panels are lacedonto a metal tube fixed on thearcs by a double lacing process(halyard/elastic). The wholeassembly was put up using the

“acrobatic” working technique,with an average finishing time ofone fabric panel every two days,with a six-man team.

Front zone The design of this covered zoneis as follows: double sheet coverand ventilation of the air pocketbetween the exterior and interiorfabric to control the ambient airtemperature above the pools.

Both the fabrics are different: - exterior fabric: fourteen

different membrane panels, 5 500 m2 in total, of thePrecontraint Ferrari type 1202 T (1 250 g/m2) with aFluotop T surface treatment,M2 fire rating and whitecolour,

- interior fabric: fourteendifferent membrane panels (5 000 m2) of the PrecontraintFerrari type 501 (650 g/m2),M1 fire rating, white colour.

The making-up consisted of thetracing piece by piece, thescraping/scratching of theassembly edges and the HighFrequency welding with a widthof 40 mm. Average assemblytime per span (exterior andinterior fabrics): three days for ateam of four men.

The architect, Karl Ratzek of atelier RATZ and form TLdesigned the new tent structure on the terrace for the traditional New Year'sReception on February 8th. This design duo has alreadysuccessfully worked together on the BMW Pavilion for the IAA Frankfort 2003.

The made to measure tentstructure, which can be dismantled, increases the space for large club events such as the New Year'sReception or the Summer Party to about 1000 m2,regardless of weatherconditions. The side walls canbe removed separately.

After an additional 1:1 windtunnel test, which confirmedthe flutter resistance of the flatsolution, it was possible toconstruct the world’s largestsingle layered ETFE foil roof. Of course, the span in bothdirections is too big for a flatlytensioned membrane.Therefore, the span in radialdirection is reduced to abearable distance by regularlyinstalled cables. The cables areanchored at the lyingframework of the secondarytrusses like the strings of a lyingharp. To avoid any deformingunder snow load they aresupported at each upper belt ofthe secondary trusses and -again like a harp - pre-tensionedagainst the lying frameworktrusses. Due to this system the bearingcables of the membrane canagain be used for the stiffeningof the upper belts of the sidetrusses and even help withsaving on steel.

The AWD-Arena is the home ofthe Bundesliga Club Hannover96 and is one of the stadiumsto host the FIFA World Cup in2006. It is successfully in usesince September 2004 and wasofficially handed over on March23rd, 2005.

3

Aesthetics and functionality:The Antilles de Jonzac

Name of the project: Les Antilles de Jonzac

Name of the client/building owner: Communauté de Communes

de la Haute-Saintonge

Year of Construction: 2002

Project Leader / Architects: R&N Hendriks / Begue et Peyrichou

Manufacture and installation of the membrane: Esmery Caron Structures

Material: PVC coated polyester

Covered surface: 11 000 m2

Membrane surface 19 000 m2

Number of workshop hours 3 300 hours

Number of hours on site 3 800 hours

Duration of erection April to July 2002

bariteau.philippe@wanadoo.fr • www.esmery-caron.com

paetzold@sl-rasch.de

www.covertex.de

4

Project DescriptionOn 8th February 2002 the decision was taken to build a new Munichsoccer stadium. The stadium will offer rain-protected seats forapproximately 65 000 spectators.The covering area of the building is split up in the roof consisting oftwo-layered white and transparent foil cushions as well as the façadewith foil cushions whose outside is printed. The printing resp. coatingwas necessary, because the soccer clubs using the stadium would liketo make its façade illuminated by the individual club colours duringthe soccer matches. This will be achieved by means of spotlightsinstalled at the inner side of the facades.Each cushion is connected to a permanent air supply and can resist asnow height of approximately 1.6 m. The sub-structure consists of concrete as far as the facade area isconcerned. Beneath the roofing 96 radial, 50m cantilevering steelframework trusses stiffened by ring purlins and trusses were built.On this structure the steel transoms are fixed, to which the rhomboidcushions are watertight connected. The transoms are arranged within96 diagonally running lines crossed by 30 ring transom lines. Thediagonal transoms are diagonally running from the bottom of thefacade towards the “shoulder of the building” and are spirallycontinuing their way within the roof area to its inner edge. 9 of a totalof 30 ring transom lines are arranged on the 40 m high facade, therest (21 lines) can be found in the roof area. Due to their crossingeach diagonal transom line, the characteristic rhomboid pattern isproduced, which is taken by the cushion geometry. For the realization of the entire building covering a period of 15months was agreed upon. Within this period all partial tasks such ascalculation of the cutting patterns of the cushions, cushionmanufacturing, production of fixation profiles, sealing techniques,ventilation and air supply systems, gutter heating, lamella fields etc.were to be planned and ordered as well as to be installed.

Choice of materialWhile the outside covering of a building usually is a thermal insulatedroof, the cushion covering of the Allianz Arena does not take such afunction. However, rain, snow and wind are kept away from thestands and inner rooms. From a thermal point of view, the cushioncovering is completely separated from the building – conventionalglass structures and insulated building structures for the inner roomsare air-conditioned.

The two main arguments for ETFE were the flexibility during formfinding and design as well as the reduced costs, as the lawn has not tobe exchanged that often due to the UV-permeability of the covering.At the moment the architects Herzog & de Meuron won thearchitectural competition the choice of material was not been finallydecided – but one soon realized that the desired geometry could onlybe reached in an economic way by using ETFE.

Figure 1: Overall geometry

Moreover, ETFE offersthe possibility of anunmixed recycling – for a total need ofabout 0.2 km2

respectively 80 tons ofmaterial, an importantenvironmental aspect.

Due to thorough fire protection reports, which proved the material’sexcellent suitability even for facade purposes, the decision for thesynthetic material was a logical consequence.

Design and illuminationA special printing considering different intensities gives the facade ahalf-transparent appearance. About 22 000 m2 of transparent foilwere continuously printed by using a specially milled roller. In order toavoid any shadowing of the pitch, most cushions of the Southernstadium area were manufactured of transparent ETFE-foils.

Different illumination schemes are possible.

Constructioncovertex developed a special fixation system for the Allianz Arenaenabling its partial installation already during the cushionmanufacturing. The pre-mounted EPDM-profile includes the edgekeder of the cushion and is clamped at the secondary steel. Betweenthe cushions a gutter system is installed sealed by flexible tracked TPOsynthetic profiles. At the cross-positions the sealing profiles arethermally welded to down pulled intersection parts (see figure 10).

The expansions of the covering caused by changes of temperature aredifferently taken by the roof and the facade: the monolithic roof canfreely expand over the facade in case there is a change of temperature,

the facade itself reduces the temperature expansions by multiplepunctual expansion joints. Only the solution developed by covertexenables to renounce the originally planned continuously runningexpansion joints within the façade covering. Arch-shaped metal sheetstake the movement amounting to severalcentimetres caused by deformation (seefigure 11, 12). This function was provedduring long-term tests. During the pulldown procedure a wave system wasinstalled at the gutter junctions of thefacade enabling a deformation of theintersection parts (see figure 14).

The Constructive Membrane BuildingThe transparent Allianz Arena, Munich

Figure 2: ETFE- Facade printed Figure 3: a sample of printedETFE-Foil with a lowtransparency

Figure 4: a sample of printedETFE-Foil with a hightransparency

Figure 14: Facade intersection part withmetal sheet to adapt for movement.

Figure 5, Figure 6, Figure 7: Illumination

Figure 8: Sample StandardCross Section Allianz-Arena

Figure 9: Cushion corner withfastened EPDM-Profile

Figure 10: Rain Gutter: TPO-Profile and cross section

Figure 11: adjustable metalsheet

Figure 12: adjustable metal sheet CAD-Model

Figure 13: Sample element witha movable boundary

Risk of water sucking due to flat roof cushionsTwelve repeatedly redundantventilation units keep theoperating pressure of thecushion facade of the AllianzArena at a constant value ofapproximately 3.0 millibar (300 Pascal respectively 0.3 kN/m2) and increase thisvalue depending on the wind-and snow loads to a maximumof 8.0 millibar (800 Pascalrespectively 0.8 kN/m2) (seefigure 15).

Figure 15: Air Supply

An emergency water outlet excludes an overload of the cushions in avery improbable case of water sucking. The specially designed solutioncan draw out rainwater into the interior of the building in anemergency case.

The automatic finding of cutting patterns3 000 cushions, 1 500 different shapes, but always the same principleof a diamond shaped geometry – an ideal precondition for using aprogrammed routine. Is the dream of a design by “pressing a button”,only a foolish idea? The engineers at covertex started already uponcontracting with a detailed elaboration of a corresponding concept.The first programmes were set up; more extensive programming jobswere awarded to a specialized software company. Only a few monthslater the team could start with the calculation of the cutting patterns.

Having exactly defined the cross section details of the clampingfixation and, thus, the cross points between the cushion and steelstructure design, covertex did set up a central data bank, which wasbased on a 3D system lines model of the architects, including morethan 700 000 details on geometry, seams, air supply and emergencywater outlet. The routines for cutting worked out 3D cushions and thecutting patterns sheets on the basis of this data entirely independentof the steel structure. Before manufacturing was started overlying thecushions with the 3D steel structure controlled their precision, themaximum deviations were only a few millimetres (see figure 18).

The manufacturing started when all relevant information was passedon to the digital cutter, which did not only cut the membrane sheetsthemselves, but also cuts out openings for air supply and emergencywater outlet junctions, and print production and installationinformation directly on the foil.

Despite all programming one cushion of the Allianz Arena is still“manually” designed – the eaves cushion running around the pitchedge of the roof, which is manufactured in four sections. Fourcushions each with a length of approximately 60 m constitute the endof the roof (see Figure 19).

SummaryMembranes enable the realization of structures with increasinglycomplex geometrical edge conditions, the lightweight fabrics allow forbig spans, even of filigree support structures. Appealing structures anddetailed solutions as well as new methods of thermal and acousticseparation contributed to the entire acceptance of synthetic materials,in addition to creative effects by colouring or printing the materials.The Allianz Arena inMunich isdoubtlessly animportant milestonein the history ofmembranestructures – and astimulus for newideas of tomorrow.

Figure 20: View at night

5

Steel structure: Max Bögl Stahl- und Anlagenbau GmbH & Co., Neumarkt

Planning of execution: R & R Fuchs, Ingenieurbüro für Fassadentechnik

Cushion calculations: Engineering & Design GbR, Rohrdorf

www.membranstatik.de

Execution of cushion facade: covertex GmbH, Obing

www.covertex.de

Material: ETFE-foil, Pneumatic two-layered

Cushion manufacturing: KfM GmbH, Edersleben

Area weight (2 layers): 700 g/m2

Light transmission (2 layers): approx. 95 %

(UV-A, UV-B-transmission approx. 94 %)

Tensile strength: 52 N/mm2

Fire class: DIN 4102 - B1

Material warranty: 10 years

Length x width x height of the roof: 260m x 230m x 40m

Horizontal cushion rings: 29

Diagonal cushion axes: 96

Cushion pressure: 0.003 up to 0.008 bar

Ventilation units: 12

Electricity consumption approx.: 1.5 up to 3.0 kW/ventilation units

Wind measuring units: 4

Snow height measuring units: 4

Flat area of cushion covering: 66 500m2

Surface of the cushion covering approx.: 2x 73 500m2

Transparent cushions: 1 014

White cushions: 1 266

Printed cushions: 480

Total number of cushions: 2 760

Lifting cushions white respectively transparent: 19

Rhomboid sheets without cushion (ventilation etc.): 24

Diagonals of smallest cushion approx.: 6.5m x 1.9m

Diagonals of biggest cushions approx.: 17.0m x 4.6m

Total air volume cushion approx.: 50 000m3

Area of ETFE-foil required approx.: 200 000m2

Weight of ETFE-foil required approx.: 80 000kg

Thickness of ETFE-foil: 0.15 - 0.25mm

Length of welding seams approx.: 250 000m

Printed area approx.: 22 000 m2

Total length of clamping profiles: 81 000m

Total length of gutter sealing: 36 000m

Number of adjustable metal sheets: 1 498

Number of emergency water outlets: 1 920

Length of air supply pipes approx.: 7 400m

Length of connection hoses approx.: 3 700 m

Duration of installation steel structure: 10/2003 until 03/2005

w.zettlitzer@covertex.de • www.covertex.de

Figure 16: Overflow Drain Figure 17: Overflow drain, Detail

Figure 18: Overlapping the 3D-Cushions withthe 3D Steel Structure for checking dimensions

Figure 19: Fastened Pneumatic Cushions installedaround the complete inner roof perimeter.

6

Figure 1 The Allianz Arena inMunich – under Construction

Figure 2 The Steel Frame with itsVariety of Angles and Geometries

Figure 3 Extruded Profiles asLiners for the Steel Beams

Figure 4 Deep-Drawn Partswaterproof the Joints

Figure 5 The Ease of HeatWelding of SUCOFLEX®-CM

Figure 6 A remarkable Buildingclose to Finish

The Soccer Stadium Allianz Arena: A pulsating oval"Architecture has to be a sensual medium" Jacques Herzog

Herzog and de Meuron have earned their reputation by continuallyexceeding public expectations and dreaming up new solutions forexteriors and facades, astounding observers time and again. The pair,both of them keen amateur soccer players, deployed this capacity for sur-prise to great effect in the bid process for the new Munich soccer stadium,the "Allianz Arena," described by Franz Beckenbauer, head of the 2006World Cup Organizing Committee, as one of the most unusual in theworld. The first match is scheduled to take place in about a year’s time,when the Allianz Arena and its pulsating, illuminated facade is expectedto captivate even non-football fans. The swirling mixture of colors andchanging intensity of light to reflect events on the field means that thestadium will appear as a vibrant, almost living organism. The oval Arena,258 meters long, 227 meters wide and 50 meters high, is a joint projectbetween Munich’s soccer clubs Bayern Munich and TSV 1860, and willaccommodate 66 000 fans on Europe’s most steeply-inclined terraces.One of the biggest highlights after the opening will be the football worldcup, to be hosted by Germany in 2006. Six matches, including theprestigious opening game and the opening ceremony, will take place inthe Allianz Arena. Herzog dismisses critics who consider the whole thingis just smoke and mirrors: "Effects, light, top players, drama, it’s all partof the show in soccer," he responds, naming his mission as providing theappropriate stage and scenery. The pair turned to traditional Englishfootball stadiums for inspiration, where the fans are as close as possibleto the pitch. "Architecture has to be a sensual and intelligent medium,otherwise it’s just boring," Herzog says.

Fluon® ETFE Foil to be used for the Allianz-Arena Soccer Stadium in GermanyAsahi Glass Co., Ltd. has received an order for about 150 000 squaremeters of fluororesin ETFE foil for the German soccer stadium Allianz-Arena, where the opening match of the 2006 World Cup in Germany isto be held. The sports facility calls for: making the side wall and roofsmooth and curved; allowing ultraviolet rays needed to grow the lawnon the ground through; and enabling a colourful performance using theside wall and roof - transparent or translucent - as monitor screens.

To realize this specification, sheets of double-layered ETFE foil, orcushions, are fit in the cells of the sidewall and roof, and then inflatedby compressed air. The product that was ordered is a high-performancefluororesin Fluon® ETFE foil (tradename "AFLEX" in Japan), whichAsahi Glass Co., Ltd. produces in its entirety including all material. Givenits superior properties, such as heat, chemical and weather resistance;anti-adhesion; excellent electrical characteristics; and transparency, thefoil has been used since its launch in 1975 in a wide range of fields,including electronics, aviation/space, photovoltaic cells, soundinsulation bags and green houses. In recent years, the Fluon® ETFE foilhas been increasingly used in Europe as a building material, since it ishighly regarded for: its transparency light; enabling curved forms; beingstain-free and easy to maintain; as well as durable and long-lived.

The Company will continue to provide solutions based on Fluon® ETFEfoil for use in construction to clients around the world, utilisingtechnology accumulated in the construction-use glass sector, forselectively enhancing the optical properties. Total cost: 280 million euros

info-pr@agc.co.jp • www.agc.co.jp/english/news/2004/0122.html http://www.allianzgroup.com/azgrp/dp/cda/0,,461492-44,00.html

The Allianz Arena in Munich willbe inaugurated in the spring of2005 and will be one of thecentral stadiums for the 2006Soccer World Championship.The arena, designed by the Swissarchitects Herzog & De Meuron,has a roofing area of 66000 m2

covered with an ETFE tensionedmembrane construction. It iscurrently the world’s biggestbuilding with such type ofroofing. The roof wasengineered and realized bycovertex (Obing, Germany) from2800 dual-layer, air-flushedETFE-cushions mounted in aframe of steel beams.The SUCOFLEX Roofing andWaterproof division of HUBER+SUHNER AG, a Swiss basedinternational company inpolymeric high-tech compoundsand products, wassubcontracted to providewaterproofing of the steel frameconstruction.An easy to install kit of extrudedliners and deep-drawn parts –protected by intellectual

property rights – was developedto cope with this task. This waterproofing system wasproduced from SUCOFLEX®-CM, considered to be mostadvanced polymeric compoundfor single-ply roofing systems.

The Requirements A complex set of individualpoints had to be fulfilled. Themost important aspects arelisted below:• Flexibility over a widetemperature range to covermovements of the steel frame.

• Ease of installation, also inoverhead mounting, rainyweather or temperatures belowfreezing point.

• Reliable heat welding proper-ties to assure a homogenousand durable liner system.

• A broad spectrum of individualand flexible blow-mouldedparts to address several

hundred different joint anglesand geometries.

• The requirements on plastics inbuilding applications: flameresistance, UV-stability, impactresistance….

The SolutionThe first parts of the system areextruded, snap-over profiles,which squeeze into the steelbeams and do not require extrafixing during installation even inoverhead mounting situations.The second components aredeep drawn liners for the steelbeam joints. These parts wereproduced on multi-segmentmoulds, which literally allowedrealizing any angle or spacing. Inthe end, more than 100 toolinggeometries were needed to copewith the Allianz roof system. Theparts were made with bellow-zones to provide additionalflexibility in areas where needed.

The joints within the systemwere realized by heat welding.Being the most state of the artolefin compound for single-plyroofing membranes, the chosenSUCOFLEX®-CM compoundshows extreme ease ofprocessing and heat-weldingwithout any pre-treatment orpre-cleaning being necessary. We are proud in havingcontributed to the Allianz-Arena. The SUCOFLEX®-CMsystem will provide maintenancefree and reliable waterproofingfor the years to come. We arelooking forward to the soccergames.

The Steel Beam Waterproofing of the Allianz Arena: A flexible System made from SUCOFLEX®-CM

www.allianz-arena.de

www.covertex.de

www.sucoflex.ch

www.dddach.orgStefan Ultsch

sultsch@hubersuhner.com

The roof of the last floor of theGarage Park of the Montreuxrailway station (Switzerland)designed by architect Luscher inco-operation with engineersPedretti (Airlight Ltd., Biasca,Switzerland) covers an area of1700 m2 and is composed of12 Tensairity® beams of about27m span, and 11 sections oftensioned single saddle shapedmembranes supported by theTensairity® beams and thevertical steel supportingstructure.

The general Contractor wasZschokke Enterprise Generale(Switzerland), which hassubcontracted the steelworks toZ&M (Aigle, Switzerland) andthe manufacturing of the beamsand the membranes toCanobbio SpA (Italy). During the design phase it waspointed out that a special siliconcoated fiberglas fabric was themost suitable fabric; this due tothe excellent fire proofbehaviour, the fact that it doesnot develop toxic gases, hasgood resistance and stabilizingproperties and a high lighttransmittance.

As for the Breitling project, thearchitect has used the beams aslight elements for the wholesurface. This is a very nice andinteresting system as it ispossible to obtain different lighteffects.

Light effects

About erection and installation:the air beams have beenpreviously assembled in the Z&Mworkshop and then transportedonce they were complete andstable. The transport was doneby train in order to reach the sitein the easiest way. Access to thesite was in fact not possible withanother kind of transport.

The individual airbeam

The installation of the beams

Once there, the beams havebeen lifted with cranes andpositioned on the verticalsupporting structure. All this hasbeen done during the nighttimein order to avoid anyinterference with the dailyrailway traffic.

Afterwards the saddle shapedpanels have been installed andfixed to the beams by means ofan aluminium “keder” profileand tensioned at the perimeter.

Laboratorium Blum (Stuttgart)has spent a large period of timeto be able to characterise thefabric behaviour. Several biaxialtests were fulfilled to be able tooptimise the calculation and tofind the adequate compensationfactors to apply.

A few problems have also beensolved to obtain the best airtightness of the beams; thosebeams are provided with acontrol system and an airinflating equipment whichchecks and keep the pressureinside the beams always atadmissible levels. The fabric hasbeen modified a few times inorder to minimise the siliconporosity, the loss of air by theseams and above all the loss ofair in the intersection betweenthe threaded rods and the upperand lower steel element.

The static calculation of thecovering has been executed withthe finite elements programANSYS 7.1, in particular for whatconcerns the Tensairity® beamsand the saddle shape mem-branes that link them. This typeof structure requires advancedcomputer calculations becauseof its double non-linearity:geometric on one hand –important displacements – andfor the behaviour of the materialson the other hand. The calculation of theTensairity® beams must takeplace by stages. The first consistsin applying the load given by theinterior pressure of the air tubeonly. The resulting efforts andthe displacements are then usedlike initial conditions for thesecond stage where the externalloads are added to the structurein different steps.

7

TENSAIRITY® PROJECT Garage Park Montreux

Name of the project: Garage Park Montreux

Architect: Luscher Architectes SA, Lausanne (Switzerland)

Contractor: Zschokke Enterprise Generale (Switzerland)

Engineering: Airlight Ltd., Biasca, Switzerland

Manufacturer: Canobbio SpA, Castelnuovo Scrivia (AL), (Italy)

Steel Supplier: Zwahlen & Mayr, Aigle, (Switzerland)

Completion: November 2004

Fabric: Silicon coated Fiberglas, Atex 5000,

PD Interglas Technologies (Germany)

Stefania.Lombardi@canobbio.com • www.canobbio.com

The saddle shaped panels of Silicon coated Fiberglas

Night views

The Forum of Cultures tookplace in Barcelona from May toSeptember 2004. Its aim was tofoster sustainability, diversityand peace through a series ofexhibitions, conferences andshows.

The Forum was built atopBarcelona’s municipal sewagetreatment plant, which wascovered for this purpose with apost-tensioned concrete slab(Fig. 1). The park’s thirtyhectares were filled with creativeexhibits on display in squares,streets and auditoriums. Thishuge area provided visitors withopportunities to watch andlisten, create, experiment, taste,discover and have their interestpiqued.

The main building was the“Forum” building, which wasdesigned by Swiss architectsHerzog & de Meuron (Fig. 2) tohouse an exhibition hall andauditorium. It was maintainedafter the event and remains atthe Forum site for use as apermanent facility.

The importance of sustainabilitywas highlighted by theconstruction of a solar platedesigned by architects EliasTorres & José Antonio MartínezLapeña (Fig. 3), which wasenhanced by its location,boldness and strength. It alsoremains on the site. It serves asboth a giant sculpture andproducer of energy.

The Forum of Cultures alsoprovided designers with anopportunity to use fabricarchitecture in the form of frametents, canopies, shelters, stagesand scenery (Figs. 4 and 5). Themost visited exhibition was the“Warriors of Xi'an”, which wasdevoted to Chinese funerarysculpture, and at which queuesof visitors were protected fromthe sun by a long linear canopy(Fig. 6). Fifteen other exhibitions

were held in double-layeredframe tents (Figs. 7 and 8).Aluminium frames supportedmembranes that were guidedinto extruded four-groovealuminium hollow profiles andstretched through telescopicdevices and screws. The doublelayering providedweatherproofing as well asthermal conditioning throughthe ventilation of the cavity.

On the sea front, the children'splayground (Figs. 9 and 10) wasbuilt from a cable netsuspended from tubular archesand filled with thin plates tosimulate glittering leaves thatmoved and chimed in the breezeblowing in off theMediterranean.

A textile roof was also designedfor the “The Giant of the SevenSeas” show to protectperformers from direct sunlightat noon (Fig. 11). However, itdid not survive its first storm.The membrane began to flutterand continued to flap until ittore. This was due to the factthat it was very flat, full of holes,improperly installed andflapping in the wind (Fig. 12).

Another application of fabricarchitecture was the “Inhabitingthe World” building, which wasdedicated to exhibits onhumankind and theenvironment. It was a bifidtension dome, whichrepresented an improvementover earlier D. Geiger cabledomes, and was designed torelieve pre-stress, providestability, facilitate installationand allow for 100%recoverability (Fig. 13).

The dome measured 20 m indiameter and was made up ofradial cables pushed up bystruts resting on hoops (Fig.14). Overall pre-stress andconvexity were provided byadjustable diagonals that liftedup the hoops and struts. Thesupporting structure was aconventional 100% recoverablelightweight tubular scaffold (Fig.15), which was returned tocommercial use after the Forumcame to close. The roof was aFerrari Mesh 31 dense net for

8

FORUM OF CULTURES,B A RC E LO N A 2 0 0 4

Fig. 1. Forum of Cultures site, Barcelona

Fig. 2. Forum building

Fig. 3. Solar pane

Fig. 4. Information tent

Fig. 5. Decorations and providing shade

Fig. 6. Shelter for visitors in queues

Fig. 7. Double layered tent frames

Fig. 8. Extruded aluminium profiles Fig. 9. Children's playground

Fig. 10. Cable-net and thin plate leaves

Fig. 11. The “Giant of the Seven Seas” stage

Fig. 12. The “Giant” under the east wind

Fig. 13. Bifid tension dome

Fig. 14. Section

Fig. 15. Lightweight tubular scaffolding

Fig. 16. Planet Earth printed on a fabricmembrane

Fig. 17. Unfolding the membrane

9

Fig. 18. Installation completed

solar protection, stabilizedagainst wind suction by twelveradial valley cables, and it had acolour image of planet Earthprinted on it (Fig. 16).

The installation process wasfacilitated by the use of amobile platform. This was usedto help place the central tensionring, unfold the membrane andtension the valley cables (Figs. 17 and 18).

As a result, the existing lightnessrecord of 50 N/m2, achieved bythe United States Pavilion atExpo ‘70 in Osaka, was broken.THE BIFID TENSION DOMEWEIGHED LESS THAN 50 N/m2 AND WAS NOTPRESSURIZED.

The success of the BarcelonaForum of Cultures hasencouraged the local authoritiesof Monterrey, Mexico, toorganize a second Forum ofCultures in 2007.

Credits• “Warriors of Xi'an”.

Design: J. B. Pascual,architect. Engineered by Arqintegral.

• “Children's Playground”.Design: E. Ruiz Geli,architect. Engineered by Arqintegral.

• “The Giant of the SevenSeas”. Designed and engineered by N. Pauli.

• “Bifid tension dome”. Design: C. Guri, C. Casajoanaand Arqintegral. Engineered by Arqintegral.

Arqintegral is a team ofarchitects: C. Garcia-Diego,J. Llorens and H. Pöppinghaus

(http://www.arqintegral.com).

More information on the “BifidTension Dome” is availablefrom the Tensinet Database:http://www.tensinet.com

2. FLATTENING ALGORITHM

The flattening function is fast and allows users to flatten any kind of patternswhatever their complexity. The strains of the fabric (for non ruled surface) areautomatically minimized and homogenized by theflattening algorithms.

For an easy optimizationprocess, flat patterns areautomatically updated whenany change is made to the 3D foam shape or sew lines.

3. ANALYZE PATTERN STRAIN,CUVATURE, SHEAR

A set of tools allows the user to analyse the feasibility of thevirtual prototype. Product feasibility is analyzed by simulating the trimmingoperation of the 2D patternsapplied to the 3D shape. For an easy optimizationprocess, flat patternsautomatically update when any change is made to the 3Dstructure or sew lines.

Design ConceptDesignConcept is a 3D/2D CAD solution for textile applications that covers the design, prototyping,pattern creation, product simulation, cost estimation and feasibility analysis of textile products usingcutting patterns such as tensile surface structures.

DesignConcept includes:3D modelling – Powerful parametric and freeform tools (surfacing and solid modelling), 3D componentlibraries and assembly and intuitive sketcher enable you to design simple or complex 3D modelsAssociative drawing tools – Parent/Child relationships between elements and files increase productivitywhen developing or modifying designs during the research and style optimization phases.Parametric drawing tools – Changing the value of the parameters in the software or in an Excel™spreadsheet causes automatically a change of the pattern shape.Minimizing physical prototyping – Visualization tools can create several trim styles from the same 3Dmodel. Moreover a faithful simulation and animation of the end product can be generated. The decision tomarket a product can be made based upon accurate virtual prototypes, thus reducing the need to producenumerous physical prototypes.Textile Rendering & Simulation – Create realistic simulations using unique “3D texture map from flatpattern” methods: stitching and trench effects, kinematics animation, dynamic camera tours and photo-realistic rendering.

4. ADDITION OF SEAM ALLOWANCE AND NOTCHES

Seam allowance and notches can be added to theflat patterns before plotting or cutting. The user-defined 3D key marks are automatically projectedon the 2D patterns and are used to create notcheslocated on the seam allowance. Seam allowancevalues, notch size and shapes can be customized inthe software.

5. PIECE PREPARATION FOR AUTOMATED CUTTING

The virtual pattern measurements are associated toautomatic nesting operations. This makes itpossible to obtain a cost appraisal in an early stageof the product development process. Thesepatterns can also be exported to other cutting orCAD tools using DXFAAMA and DXF/DWGformats.

DesignConcept is a registered trademark of Lectra • www.lectra.com • f.charriaud@lectra.com

Josep Llorens,

ignasi.llorens@upc.edu

http://www.upc.edu/

ca1/cat/recerca/

tensilestruc/portada.html

1. 3D PATTERN CREATION

By designing 3D patterns on top of theshapes 2D patterns are automaticallyobtained, whatever their complexity.The tool is based on Nurbs. The usercan draw freely a curve “region curve”that represents the position of theseam, sew or weld lines in order todefine the 3D pattern. The position ofthose lines can be defined on the 3Dmodel. The 3D pattern is defined by aregion: a 3D mesh made by triangles.This automatic mesh depends onsurface and region curve location. This mesh can also be smoothed by an algorithm to avoid bad triangles: a bad triangle is much stretched.

The “Atlantis” project, designedfor emergency accommodations,consists in a multi-centeredaluminium dome structure. Thedome is easy to carry and risewith self-assembly capabilities ofa peripheral rod cable and acenter lift truck.

The diameter of the dome is afunction of the surface that mustbe covered (500-1000m2).The load carrying structure isconstituted by 24 archedsegments assembled with rods in6061-T6 Al alloy. The dome configuration will beobtained by means of 24 singlesegments joined together threeby three in the lifting phase.

Wheels are added to the externalpoints of the arch in order toallow its displacement. A steelcable will be positioned betweenthe two ends (internal and exter-nal) to avoid a possible failure ofthe arch under its own weight.Simple rods are connected atpre-defined angles by means ofaluminium ball joints. After therods are assembled, theirrotation is blocked by theparticular typology of the jointthat provides the right finalshape of the arch.The assembly begins with theopening of two groups of rodsthat , in a second step, are placedone on top of the other to create

an X-shape that constitutes onearch of the dome.The rods, making use of themovements provided by theconnection joint, reach theposition of maximum opening.They overlap and are hinged bymeans of screw and bolt(forming the X). The assembly isentirely carried out on theground.

Complex rods are positionedafter the deployment of thesimple rods and are characterizedby an upper section to which thecovering panel will be connectedand locked with an aluminiumcover joint.

The structure isreinforced witha 14 mm steelcable at theexternalperimeter and

another 8 mm steel cable at theinternal one. These cables, whichpass through proper pulleys, areset under tension by a motorwinch from the lifting mechanism.The covering panels can bemade from EFTE or aluminiumpanels that will be attached tothe load carrying structurebefore the lifting phase.

alessandra.zanelli@polimi.it

The research unit EXTRA is developing educational contents in thefield of contemporary architecture technology and its criticalcomprehension. EXTRA is an information network striving forsustainable interventions and aspiring to accurate detail. It embracesvarious subjects in design processes important for teachers,researchers and graduating students on the following items:1. Technological culture in architecture design: construction

processes, innovation, connections, environment;2. Innovative construction systems for architecture;3. Environmental sustainability of building production and

architectural design.

EXTRA is investigating in two different fields: light weight technologiesand temporary building systems.On one side, the research unit is interested in developing a researchcalled ECO-CASE, in order to support decision-making in evaluatingenvironmental charges, energy consumptions and costs in thebuilding sector. On the other side, EXTRA improves a disciplinary collaborationbetween different academic institutes for application of lightweightsystems and demountable buildings for dwellings.

TWO EXAMPLES ILLUSTRATE THE ACTIVITIES OF EXTRA:

C-Argo: Mobile dwelling unit with shells in ETFE/THV-filmArchitect Graduate: Elena Biglia and Ombra Bruno

Tutors: Guido Nardi and Alessandra Zanelli (Politecnico di Milano),

Ben Morris (Vector Special Projects)

10

A C A D E M I C INSTITUTIONS

TensiNet will assemble a list ofuniversities dealing with TextileArchitecture in terms of researchand/or education. They will bementioned one by one in TensiNews.

EXTRA unità di ricerca in sperimentazione dell’architettura

EXperimental Technological Researches on ArchitectureDepartment of Building Environment Science & Technology (BEST)

Anna Mangiarotti (coordinator), Andrea Campioli, Marisa Bertoldini, Alessandra Zanelli,Monica Lavagna, Ingrid Paoletti, Carol Monticelli, Eugenio Morello

The "Atlantis" Project: Ephemeral, deployablearchitecture for emergency accommodationArch. Graduate: Francesco Peyronel, fpeyronel@yahoo.com

Tutors: Andrea Campioli and Alessandra Zanelli (Politecnico di Milano),

Mario Fortini and Roberto Mantelli (Global Service)POLITECHNICO DI MILANO

Thin compression-stressed shell structures as well as tension-stressedmembrane structures are lightweight structures. They are quite similarnot only with respect to their double curved shape, which stabilises thestructure, but also with respect to the load bearing behaviour. Like thetension-stressed structures, the compression-stressed structures reactto external forces by membrane or normal forces and not orinsignificantly by bending forces. The curvature – synclastic oranticlastic – and also the steadiness of the shape and the low bendingstiffness of the slender cross section are basic characteristics of bothstructures.Whereas there are good and economic building methods for tensilesurface structures, double curved shell structures are still not verywidespread because of the extensive building requirements. Because ofthe similarity in the shapes of the load bearing systems an obviousmethod is to create shell structures by 'stiffening' tensile surfacestructures. In addition to mechanical pre-tensioned anticlastic curvedmembrane structures there are pneumatic structures in consideration.By systematic investigations of potential appropriate methods for thestiffening of tensile membrane structures in the context of the researchprogramme “Natural Growth of Structures for the Building Industry”at Nürtingen University, a wide range of new and effective methods forcreating shell structures were found. Two of them were analysed withlarge scaled models.

Textile reinforced pre-stressed concrete shell

Double-wall fabrics are based on the velvet weaving technology,whereby piles, which are integrally woven into the two layers, connecttwo layers. As with single layer fabrics, it is possible to define thecharacteristics of the fabric by conditioning the threads and thecoating. Using a cutting pattern it is possible to shape the fabric into adouble-curved surface by mechanical or pneumatical pre-tension.When self-compacting concrete or cement glue is filled into the hollowspace of the 3D fabric, the result after hardening is a monolithicconcrete shell of even thickness. Now it is possible to remove the shape-defining forces, for instance with deflation of the pneumatic structure.The former pre-tension of the membrane is transferred into thecompression pre-stress of the concrete. No additional steelreinforcement is necessary. Although the pre-stressing level of theconcrete is relatively low, it turned out that it is possible to design it highenough for the special load-bearing system of slender shell structures. The prototype was made of a sheet of PVC-coated Polyester double-wall fabric of approximately 1.90m x 2.30m welded together from 3panels, due to its easy availability. The plane surface was brought intoa synclastic shape with a height of 0.16 m only by elongation of themembrane under a pneumatic pressure of 75mbar. The distance between the fabric layers and as a result, the thickness ofthe shell structure was 7mm. The stiffened shell was loaded by

depression, simulating planar forces and by local acting point forceswith very low deformation showing an adequate load-bearingbehaviour. The experiment shows the feasibility of the building methodand gives hope for an economic realisation of bigger textile-reinforcedpre-stressed concrete shells, if appropriate resistant fibres are used.

Pre-stressed concrete grid shell

In general grid shells worksimilarly to continuous shells,under the premise of sufficientshear stiffness of the surface.Therefore, grids with triangularmeshes look particularly suitable,but the building method is verycomplex, because of the differentlengths of the linear elementsand the different angles at theknots. In addition to the stabilisation ofthe shape during the buildingprocess, facilitated by a tensilesurface structure, thisgeometrical problem of theindividuality of the single meshelements is solved by theconstruction method developed.The structure is assembled as aflat net of flexible tube-like basicelements, which can be producedas identically serial parts. Theyform a continuous hollow spacewhere continuous steel cables areadded. The structure can then beformed into a double curvedshape by use of mechanical orpneumatic form-findingprocesses, whereby theelongation of the flexibleelements on a rubber membranedefines the designed shape. Thesteel cables slide inside thehollow grid structure until theyattach to a predefined limit stop.

The pressure of the pneumatic structure is then further increased tocause a high stiffness of the formerly soft structure, while the cablesbear a relatively high pre-tension. Now a self-compacting concrete canbe filled into the grid structure, which is hollow throughout. Afterhardening, the pressure in the pneumatic structure can be deflated anda monolithic grid shell with triangular meshes is complete. The pre-tension of the cables transfer to a pre-compression of the concrete,which provides the system with an extraordinary load-bearing capacity.The first model-prototype grid shell has the size of approx. 4.20m x6.00m and a height of 0.55m while the cross section of the extremelyslender rods is d = 18mm with a mesh width of 0.75m and a steelcable of d = 3mm. It shows both the height capability and the easy-to-handle building method of pre-stressed concrete grid shells withtriangular meshes.Both construction methods shown are highly demanding of architectsand engineers because they have to design and calculate not only thefinished shell structure but the construction process whichincorporates a tensile surface structure.

11

Innovative building methods of shell structuresHochschule Nürtingen, Institute for Applied Research

www.fh-nuertingen.de • info@stev-bringmann.de

www.archcon.de • info@archcon.de

The inflated fabric: 1.9m x 2.3m in plan

The inflated fabric: the height is 0.16m

The distance between the 2 layers is 7mm

The behaviour of the shell under local externalloading

The inflation of the grid of 4.2m x 6.0m

The inflation up to a height of 0.55m

The pre-stressed concrete grid shell

The slender rods have a diameter of 18mm

A typical node

12

Introduction

Textile membrane structures arenot so widespread in Bulgariaand their calculation, design, andfabrication are not well knownamong the engineers involved inpractice. The first lightweighttension membrane structure wasbuilt for the reconstruction ofSofia’s Central Railway StationSquare in 2003 (Fig.1). Theforeign consultant firm(Graboplan Kft) designed thetextile membrane and theauthors of the present paperdesigned the supporting steelstructure.

Some important questionsconcerning the realization of thisproject remain unanswered:• How to control the stress over

the surface during the initialprestressing and how to ensurethat the design prestress fromthe numerical model will berealized on the building site?

• Is it possible to prestressappropriately a conical shapedmembrane surface (also theassembly of conical surfaces in onesurface Fig.1) only by pushing thehigh points upward?

• What is the percent ofrelaxation in textile membranes

at biaxial tension and is itimportant for the service periodof the structure?

Based on these questions theauthors of the present paperinitiate a Ph. D. research at theDSTPS to investigateexperimentally and numericallythese kinds of problems. An experimental model wasdesigned with the help ofSOFiSTiK software (Fig 2), which has special modules for form-finding “ASE3” and“ASE4” based on the modifiedNewton method and cuttingpattern module “Textile” fortension structures. For therealization of the experiment asmall group of studentsinterested in tension structureswere attracted and involved inthe design process.

Experimental model

For the purpose of theexperiment a frequently usedbasic shape has been chosen,namely the conical form. Themembrane surface wassupported by a steel space framewith dimensions in plan of 6m x 6m and a height of the topring of 4.5 m (Fig. 3). The textile membrane wasattached to the steel ropes at theouter boundary and to the steelring at the central high point (Fig. 4, 5). The Precontraint 705PVC coated material was usedfor manufacturing of themembrane. It was supplied bythe sponsor firms “KAMMEKS”,which donate the material and“Uniart & CO” responsible forcutting, assembling andtransportation of the surface.

All the experiments were done inthe structural laboratory ESRL(Educational and ScientificResearch Laboratory) of theDepartment of Steel, Timber andPlastic Structures at University ofArchitecture, Civil Engineeringand Geodesy – Sofia.

The scope of the experiment

The scope of the experiment waslimited to the investigation of theentire structure in the process ofprestressing and the simulationof a series load cases for snowloading. Wind loading was notconsidered at that stage. Thesnow loading was tested withfive cases: one symmetrical overthe entire model and four nonsymmetrical cases, which wereconsidered as the most typicalfor the chosen shape. All loadcases have been realizedgradually by a preliminarydefined scheme for placing theloads. Four different types ofsacks (10kg, 8.6kg, 7kg, and4kg) full of sand were used forthe simulation of the snow load(Fig. 6). All sacks were placed insuch a way that they adequatelysimulate a real snow loading.Every load case was applied stepby step.

Experimentalinvestigation

of a conical shapedtextile membrane

under snow loading

Table 1: Results of the experimental and finite element model – forces and deformations

Loading case Model Forces Relative deformations at the inductive transducer

Ro R1 F_tr N6-6 ε2 ε3 ε4 ε5 ε6 ε7 ε8 ε9 ε10

[kN] [kN] [kN] [kN] % % % % % % % % %

Initial Num. 21.7 21.7 - -14.1 1.36 2.08 1.88 5.68 4.40 2.69 2.20 7.58 7.38

prestressing Exp. 3.4 3.5 -10.9 -6.7 -0.34 -0.52 0.47 1.42 1.10 0.69 0.57 1.92 1.69

Symmetrical Num. 19.1 19.5 - -24.3 5.46 6.96 9.25 4.15 1.41 1.25 0.80 0.69 0.45

snow load Exp. 6.0 6.8 - -25.3 1.56 1.99 3.02 1.49 0.47 0.30 0.33 0.29 0.14

Non symmetrical Num. 20.3 19.7 - -19.4 2.56 2.08 4.45 3.7 0.79 1.24 0.69 1.09 1.8

snow load Exp. 4.5 6.2 - -16.4 0.83 0.67 1.46 1.22 0.26 0.32 0.23 -0.37 -0.58

Fig. 1 Textile membrane on Sofia’s CentralRailway Station Square

Fig. 2 Form-finding model in SOFiSTiK Fig. 3 Supporting Steel Frame Fig. 4 Assembling the membrane

Fig. 5a Force transducer 1 and inductivetransducer 7

Fig. 5b Inductive transducers 3 and 4 Fig. 5c Inductive transducers 2 and 8 Fig. 6 Nonsymmetrical snow loading.

The measurements were doneafter every step. Themeasurements were done afterthe attenuation of thedeformations and deflections.

Some important results

The analysis of the resultsincludes the following three loadcases: initial prestressing, snowload over the entire surface(service load 0.7kN/m2) andsnow load over half the surface(service load 0.7kN/m2). Forclarification, the results are listedin Table 1, where:• Ro, R1 – axial force at

boundary ropes• F_tr – axial force at force

transducer, measuring theforce in the hydraulic jack

• N6-6 – axial force at the centralpylon

• ε2, ε3, ε4, ε5, ε6, and ε7 –relative deformations at themembrane in radial sections

• ε8, ε9, and ε10 - relativedeformations at the membranein tangential sections

At the stage of prestressing themembrane, the results of theexperimental set-up areconsiderably different of thoseobtained with the numericalmodel. The main reason for thediscrepancies is the fact that thecorner tension bars are notmodelled in the finite elementmodel. The levels of the tensionat the membrane surface, as awhole are considerably lowercomparing with those of the FE-model.

The stated differences lead tothe conclusion that for theparticular membrane structuretested the optimal prestressingof the conical shape cannot bedone only by lifting the centralpylon. Previously tested axiallyloaded samples of the samematerial have shown levels ofrelaxation up to 30 to 33%.However, the relaxation at bi-axial tension is at the level of 14to 16%, which was measuredduring the experiment.

The non-symmetrical loadingsare more unfavorable and forproving the serviceability it isobligatory to check the structurefor those loadings.On the base of the analysis thenext more importantconclusions can be stated:

• The results of the experimentalinvestigation showed that forthe conical shaped surface theprestressing of the membranenear to the high points couldeasily be done by means ofpushing upward the highpoints. On the other hand,regions near to the perimeter(lowest part of the membrane)have to be prestressedadditionally by means of theboundary cables. Theprestressing of huge structuresas well as structures composedof numerous conics unifiedinto one surface might also notbe achieved solely by the liftingof the central pylons. Thecompensation of the boundarycables has to be ensured.

• The relaxation of themembrane at bi-axial tension isat the order of 14 to 16% andhas to be taken in to accountduring the design of thestructure;

• Applied non-symmetrical loadslead to larger deformationsand displacement compared tothe symmetric load with thesame intensity.

SummaryThe experimental investigation ofthe conical shaped membranesuggests that for the correctrealization of such kind ofstructures numerous ways fordifferent prestressing have to beensured. The control during theoperation of prestressing has tobe done by measuring the forcesat boundary cables or thedeformations on the supportingstructure. A precise FE-modelhas to be created to ensure thatthe deformations and thedisplacements of the system areclose to the real one.

University ofArchitecture, Civil Engineering andGeodesy - Sofia

Department of Steel, Timber and Plastic Structures(DSTPS)

13

Dimitar Dakov

Dakov_FCE@uacg.bg

Vatyu Tanev

Tanev_FCE@uacg.bg mail@textile-roofs.com • gruendig@inge3.bv.tu-berlin.de

F o r t h c o m i n g E v e n t s

Textile Roofs 2005The Tenth International Workshop on the Design and Practical Realisation of Architectural Membrane StructuresMay 26th - 28th 2005, BerlinIn addition to a comprehen-sive programme of lecturespresented in English by keyfigures from the membranestructure industry andacademia, opportunity forthe study and hands-ondevelopment of practicalcase-studies in an informaltutorial environment will beprovided.During the afternoons thehands-on workshops will berun with opportunities forboth computational andphysical modelling.Rosemarie Wagner andMichael Schultes plan toorganize a tutorial forstudents on pneumaticstructures. In parallel to thispractical activity, specialisedlectures will be presented onstate-of-the-art topics for themore advanced participants.

These will includealgorithmic approaches,computational algorithmtheory and textile technologyas well as corporatepresentations fromprominent lightweightstructure firms. On Thursday evening thespecial guest lecture will begiven by Prof. Kröplin fromStuttgart University.

The report of last year’sevent is available athttp://www.tensinet.com/documents/general/!Report_Textile_Roofs_2004.pdf

2ND LATIN AMERICAN SYMPOSIUM SymposiumCaracas, Venezuela 04/05/2005 > 06/05/2005www.arq.ucv.ve/idec/simposio/

RETROSPECTIVE ON THE LIFEWORK OF FREI OTTO ExhibitionStuttgart, Germany 10/10/2004 > 13/10/2004www.architekturmuseum.de

TEXTILE ROOFS 2005 WorkshopBerlin, Germany 26/05/2005 > 28/05/2005www.textile-roofs.com/TR2005/index.htm

IASSIACM2005 International ConferenceSalzburg, Germany 01/06/2005 > 04/05/2005www.iassiacm2005.de

TECHTEXTIL FRANKFURT Trade FairFrankfurt, Germany 07/06/2005 > 09/06/2005www.techtextil.messefrankfurt.com/frankfurt/en/home.html

CCC 2005: THIRD INTERNATIONALCONFERENCE COMPOSITES IN CONSTRUCTION International symposiumLyon, France 11/07/2005 > 13/07/2005www.ccc2005.univ-lyon1.fr

IASS 2005 International symposiumBucharest, Romania 06/09/2005 > 09/09/2005www.incerc-cluj.ro/iass2005/

STRUCTURAL MEMBRANES 2005 ConferenceStuttgart, Germany 02/10/2005 > 04/10/2005www.congress.cimne.upc.es/membranes05

FABRIC STRUCTURES 2005 ExhibitionSan Antonio, Texas 26/10/2005 > 27/10/2005www.ifaiexpo.info/

TENSINET ANNUAL GENERAL MEETINGStuttgart, Germany 03/10/2005http://www.tensinet.com/

Textile composites andinflatable structures arebecoming increasingly popularfor a variety of applications in -among many other fields - civilengineering, architecture andaerospace engineering. Typicalexamples include membraneroofs and covers, sails, inflatablebuildings and pavilions, airships,inflatable furniture, airspacestructures etc. The objectives of STRUCTURALMEMBRANES 2005 are tocollect and disseminate state-of-the-art research and technology

for design, analysis, constructionand maintenance of textile andinflatable structures. The ability to provide numericalsimulations for increasinglycomplex membrane andinflatable structures is advancing

rapidly due to computerhardware development and theimproved maturity ofcomputational procedures fornonlinear structural systems.Significant progress has beenmade in the formulation offinite element methods for staticand dynamic problems, complexconstitutive material behaviour,coupled aero-elastic analysis etc.The conference will addressboth the theoretical bases forstructural analysis and thenumerical necessary for efficientand robust computer implemen-tation. A significant part of theconference will be devoted todiscuss advances in new textilecomposites for applications inmembrane and inflatablestructures, as well as in

innovative design, constructionand maintenance procedures. Sessions related to specifictopics of the conference will beintroduced by a keynote lecturein the respective field. Thesekeynote lectures will be comple-mented by invited sessionsorganised by recognised expertsin targeted research and appliedareas, as well as by contributedpapers. Structural Membranes2005 aims to act as a forum fordiscussing recent progress andidentifying future researchdirections in the field of textilecomposites and inflatablestructures.

membranes05@cimne.upc.es

http://congress.cimne.upc.es/

membranes05

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Structural Membranes 2005International Conference on Textile Composites

and Inflatable Structures2-4 October 2005, Stuttgart

Shell Structures without Formwork Innovative ManufacturingMethods for Shell Constructions by StiffeningDipl.-Ing. Stev Bringmann, Prof. Dr.-Ing. Siegfried Gaß, Dipl.-Ing.(FH) Elke Strauß, Fachhochschule Nürtingen (D)

BIFID Tension DomeProf. Josep Llorens, School of Architecture, Barcelona (E), Ch. García-Diego, H. Pöppinghaus, Arqintegral, Barcelona (E)Solar Roofing Membrane Compound SystemsAndrea Glawe, Thomas Kolbusch, Coatema Coating

Machinery

GmbH, Dormagen (D)Utilization of Solar Energy with Textile Heat AccumulatorsDr. Barbara Pause, Textile Testing & Innovation, LLC, Longmont (USA)Identification of Shear Stiffness for Soft Orthotropic Textile CompositesKateryna Vysochina, A. Gabor, D. Bigaud, S. Ronel-Idrissi, MechanicMaterials & Structures, Laboratory Claude Bernard University Lyon (F)Temporary, Adaptable and Convertible Membrane StructuresUniv. Prof. Dr.-Ing. Bernd Baier, Universität Duisburg-EssenBauwissenschaften, Konstruktive Gestaltung-Leichtbau, Essen (D)Appropriate Modelling of Textile for the Design of Surface Stressed StructuresErik Moncrieff, Kurvenbau, Berlin (D)Textile Solutions for FassadesDipl.-Ing. Raimund Apel, ARGE Smart, Kassel (D), Henry Koch, Planungsbüro Koch & Partner, Kassel (D)New Church of St. FranziskusDipl.-Ing. Annette Hartung, Lichtplanung Hartung, Köln (D)New Membrane StructuresEnd Dipl.-Ing. Arch. Gerd Schmid, form TL, Ingenieure für Trag- und Leichtbau GmbH, Radolfzell (D)

13th International Techtextil Symposium6 - 9 June 2005,

Congress Center Messe Frankfurt

The Techtextil Symposium isdesigned to make existing trendsvisible and to promote newdevelopments, i.e., to transfernew developments fromresearch to production. At thesame time, the Symposium aimsto intensify the interdisciplinaryworking relationship betweenscience, industry and users.

The Buildtech topic ‘Lightweight+ Membrane Construction’ will be presented on the 8thJune 2005, 9:00 am - 1:30 pm with the following contributions:

The mainemphasis ofthe Inter-nationalStudentsSeminar is todevelop and manufacturebuilding models for tensionedand inflated membrane struc-tures, and to experience theprocess of development andmanufacturing up to the finaland real model. Interest in newways of thinking and unusualapproaches is affecting theappearance of the buildings.The design of membrane

structures is deeply related to thebehaviour of the fabric and thepossibility to tension, to join andto fix the materials. Thereforeone of the targets of the seminaris to point out the relationbetween form, material beha-viour and structural behaviourwhich can be realized duringmanufacturing and construction. A further aim is the get practicalexperience in designing and

manufacturing tensioned andinflated membrane structures.The practical experience ishardly to teach using computermodelling neither for the 3d-shapes and animations norfor numerical simulation of thestructural behaviour. The gapbetween virtual designedstructures and the real buildingis getting wider and one of the aims of the internationalseminar is to show thepossibilities and differencesbetween physical modelling and computational design.Participants of the Seminar are

selected students -from differentfields of study -with great interest

in and enthusiasm for tensionedstructures. The International Studentsseminar is co-ordinated byLothar Gründig from theTechnical University of Berlin,the University of Applied ScienceBielefeld/Minden, RosemarieWagner from the University ofApplied Science Munich and P. Michael Schultes responsiblefor the module experimentalbuildings at the TU Vienna.Pictures from ‘Aufgeblasene Architektur’ by P. Michael Schultes, Wien

de-light and air International Students Seminar at Textile Roofs

Mai 24th – 28th 2005 , TU Berlin

R.Wagner@fhm.edu

On the occasion of Frei Otto's80th birthday theArchitekturmuseum of the TUMünchen at the Pinakothek derModerne is preparing anextensive retrospective on thelifework of this great architect,designer, scientist and visionary.Frei Otto's systematic researchof a lightweight and adaptableconstruction, his earlydedication to environment andecology as well as his impressivepersonality turned him into anoutstanding architect in thesecond half of the 20th century.His works offer an inexhaustiblesource of inspiration andreflexion.

"Frei Otto – LightweightConstruction, Natural Design"is the first major survey on thisuniversal architect. Scientifically compiled at theTechnische UniversitätMünchen it shows the span of

his 50 years' work by means ofdrawings, sketches, models andhistoric documents.

Frei Otto will provide thecomplete original material forthis exhibition, thus making itpossible to experience theastonishing variety of his worksfor the first time. Along with the exhibition a filmon Frei Otto will be shown,initiated and supported by theArchitekturmuseum andproduced by Louis Saul in acoproduction of Südwestfunkand arte.

With approx 50 000 visitorsevery month the Pinakothek derModerne is the most frequentlyvisited German museum. Thepresentation reflects Frei Otto’sessential concern: naturalnessand lightness and culminates inFrei Otto's vision: "How do wehave to live on in the future? –We must think more, research,develop, invent and dare moreto allow all human beings apeaceful life in a natureprotected by themselves."

For the first time an extensivepublication (German andEnglish version) by BirkhäuserVerlag will show the completeworks of Frei Otto.

OPENING: 25 MAY 2005

DURATION: 26 MAY >

28 AUGUST 2005

The famous German architectand engineer, Frei Otto, is thewinner of one of architecture’smost prestigious prizes, the RoyalGold Medal. Giving therecognition of a lifetime’s work,the Royal Gold Medal isapproved personally by herMajesty the Queen and is givenannually to a person or a groupof people whose influence onarchitecture has had a trulyinternational effect.

Frei Otto on the German Pavilion in Montreal at the EXPO 67

Born in 1925 in Siegmar, Frei Otto, who’s pioneering tensile structuresand grid shells inspired architects such as Richard Rogers, MichaelHopkins and Ted Cullinan, is responsible for the revival of the tent asa feature of modern architecture. His interest in applications of modern technology and research intonatural forms has led him to be regarded as a world-rankinginnovator in architecture and engineering. Frei Otto was a visitingProfessor at Washington, Yale, Berkeley, and Harvard universities, aswell as at MIT. He also held a Professorship at the TechnicalUniversity in Berlin where he himself studied at the beginning of hiscareer. He has received many international awards and honours, andhas published a variety of works on tensile and pneumatic structures.His most famous projects include the West German Pavilion at theMontreal Exposition in 1967 and the roofs over several of the sportsstructures at the 1972 Olympic Park in Munich.

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Frei Otto wins the Royal Gold Medal

http://www.architecture.com • b.burkhardt@tu-bs.de

www.architekturmuseum.de

archmus@lrz.tum.de

RETROSPECTIVE ON THE LIFEWORK OF FREI OTTO LIGHTWEIGHT CONSTRUCTION - NATURAL DESIGN

Frei Otto in the IL Institute at the Stuttgart University

Experiments with soap films at the IL

Experimentson structures

The IL Tent during test phase for the MontrealPavilion in 1965 at the Stuttgart UniversityGlobal view on structures in nature and techniques, sketch by Frei Otto

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Frank Jensen who presented a general design methodology for single-degree-of-freedom expandable blob structures gave a very inspiring lecture. This takes his previous PhD-research onfoldable plates, conducted under the supervision of Prof. S. Pellegrino of the Deployable Structures Laboratory inCambridge, one step further by adding a third dimension. All this is based on expandable bar structures pioneered by Hoberman and later extended by You and Pellegrino.

Frank Jensen proposed solutions for expandable plate structures wherethe location of the hinges connecting the plates coincides with theirlayout in a ‘parent’ bar structure. Several plate elements are connectedtogether to form a radially expandable plate. Provided that somekinematic conditions are satisfied, several layers of these plates can beconnected together to form a three-dimensional expandable blobstructure. With this method buildings can be designed that are able toalter their plan shape and thus their overall volume.

Retractable plate structures [1]

Retractable blob structure [1]

Pictures from:[1] Concepts for Retractable Roof Structures, PhD-dissertation, F.V.Jensen, Oct. 2004, University ofCambridge

Abstracts and papers are published in:R. Motro (ed), 2004 “Shell and Spatial Structures from Models to Realization”Editions de l’Espéron, Montpellier ISBN 2-912261-22-8

A more complete report is available athttp://www.tensinet.com/documents/general/!Report_IASS_2004.pdf

The scope of the symposium covered all aspects of Shell and Spatial Structures and included topics ranging from design of shell and spatial structures to mechanics,morphology, materials and realization.

L I T E R A T U R E ISBN: 3-7913-3049-7

Pages: 224

Published: 2004, Prestel

Price: $136.8

IASS 2004 Shell and Spatial Structures from Models to

Realization, organized by the UniversityMontpellier II and chaired by Prof. R. Motro from

20th to the 24th of September 2004

Frank Jensen, fvj@sj.dk • Niels De Temmerman, niels.de.temmerman@vub.ac.be

Abstract This book provides information about numerous innovations in the field of materialsdevelopment, technology and design applications including the history, materials and use ofmembrane structures.There are contributions from Brian Forster, Knut Göppert, Thomas Herzog, John Pudenz, Bill Taylor, and David Wakefield.

Klaus-Michael Koch with Karl J. Habermann

Membrane StructuresInnovative Building with Film and Fabric