Tensi ewsNEWSLETTER OF THE EUROPEAN BASED NETWORK FOR THE DESIGN AND REALISATION OF TENSILE STRUCTURESw 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 . 1 0 - A P R I L 2 0 0 6 - P U B L I S H E D T W I C E A Y E A R

Editorial Board: Mike Barnes, John Chilton, Brian Forster, Peter Gosling, Marc Malinowsky, Marijke Mollaert, Peter Pätzold, Rudi Scheuermann, Javier Tejera, Thomas Van der Velde

Coordination: Marijke Mollaert, phone: +32 2 629 28 45, marijke.mollaert@vub.ac.be Address: Vrije Universiteit Brussel (VUB), Fac. of Engineering, Dept. of Architecture, Pleinlaan 2, 1050 Brussels, fax: +32 2 629 28 41

Tensi ews info

Editorial

This is the fourth issue of TensiNews since EU funding for the establishment of TensiNet ceased and the organisation became self funded – principally through industrial sponsorship by the major partners, although supplemented by a significant number of individual, company and university membership fees. TensiNet is now on a sound financial footing to cover its publication, symposia and web support costs (which to some extent have previously been supplemented by staffing provided at the VUB in Brussels). An expansion of the support has come about through the former Working Group for Tensile Architecturewho have now joined TensiNet as full partners. One effect of this is that TensiNet will in future be sponsoring theinternational student design competition (see article in the current issue of TensiNews). Other wider considerations, which are raised in the short article about the working group meeting (page 2) are:• the possibilities for further collaborations or amalgamations with other groups• a possible reconsideration of the aims of TensiNet, or revision of emphasis• a possible review of the constitution or management of TensiNet

In relation to the latter two aspects it seems appropriate to emphasise that TensiNet was set up with EU funding to be a Europe wide network for the dissemination of information relating to Tensile structures(particularly prestressed membranes) and to become an industry sponsored trade, professional and educationalorganisation managed, according to its constitution, by its founding and subsequent industrial partners. That is a verybroad aim and it allows plenty of scope for the organisation to develop however it may wish, and there will be a naturaleffect for the principal partners who provide most funding to shape future policy, including of course the question offurther collaborations. In that context there are three levels of collaboration:• the first is National – there may be good organisational and perhaps commercial reasons for the formation of

local (or national) branches of TensiNet – see for example the article on page 2 concerning the meeting in Madrid• the second is Europe wide – in other words increasing the emphasis on the original aims of TensiNet which, in

addition to the exchange of information at the professional and educational levels, also had the intention ofproviding a forum for potential collaborations in research and development, and the development of design guidesand eventually codes of practice

• The third is International – for example, in a worldwide context there are four Lightweight Structures associations– LSA in the US, LSAA in Australia, TensiNet in Europe and MSAJ (membrane structures association of Japan).Most of these have already agreed in principle to collaborate in the setting up of International Symposia

TensiNews is really an industry news forum, especially relating to new projects. It is not intended to be a magazine forresearch and the articles are not refereed (or particularly vetted and edited), but it might be appropriate to have aletters section and perhaps some of the issues raised above could be discussed more widely.

Marijke MollaertMike Barnes

2Forthcoming Events

Meeting Working Group for Textile Architecture

Regional TensiNet Meeting

3Cooltrax®

Intelligent shading material

4Desert Seal

A Tent with active Cooling

5New tensioning system

for textile façades

6Chemically Rigidized

Expandable Structures (CRES)for Space Application

8Mechanical behaviour

of coated fabrics and films usedin prestressed textile engineering

10Literature

International workshop‘Textile Roofs 2006’

11International Students Seminar

‘de-light and air’

12Student Competition

'Textile Structures for New Building 2007'

Fabric Boat

13Multi-event area

“Los Teros de Melilla”

14Buitink Technology

entrance of Dolfinarium

15Roof Tent Structure

Khoraisch Road Retail CenterUnobtrusive Canopy 2The “Lleida” prototype

16“The Oyster”

Casino del Aljarafe, Sevilla Textile roof for a stand

at TSV Gersthofen

2

Tensi et partners

Ceno Tecwww.ceno-tec.de

Dyneonwww.dyneon.com

Form TLwww.Form-TL.de

IMSwww.ims-institute.org

Laboratorium Blumwww.labor-blum.de

Kurvenbauwww.kurvenbau.com

Messe Frankfurt/Techtextilwww.techtextil.de

SL-Rasch GmbHwww.sl-rasch.de

Schlaich Bergermannund Partnerwww.sbp.de

Vrije Universiteit Brusselwww.vub.ac.be

Universidad Poletécnicade Madrid www.aq.upm.es

Technical University of Berlin www.survey.tu-berlin.de

technet GmbHwww.technet-gmbh.com

Tensotech Consultingwww.tensotech.com

Tentechwww.tentech.nl

Verseidagwww.verseidag.de

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/

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

form TL

Ferrari sawww.ferrari-textiles.com

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

Architen Landrellwww.architen.com

Group ALTO

The following members of the Working Groupfor Textile Architecture did attend the meetingin Frankfurt: Mr. Driesch, Verseidag; Mr. Frisch, Dyneon; Mr. Kleibel, Taiyo Europe;Mr. Jännecke, Messe Frankfurt; Mr. Hohlstein,Messe Frankfurt; Mrs. Heidrun Bögner,TensiNet.

As mentioned in previous meeting reports theWorking Group for Textile Architecture willjoin the TensiNet Association and will nolonger continue its activities as anindependent Working Group.The three companies Verseidag, Dyneon andTaiyo expressed their intention to join theTensiNet Association as a partner.The following main points we discussed: The new partners paying 2400 euro expect toget more power in the management boardthan the founding partners paying much less!

Is it possible that a whole association joinsthe TensiNet Association so that theirengineers get total access? What would be the fee? Is the TensiNetAssociation interested in working togetherwith other associations like the BKTex or IVK(engineering association for synthetics)?On the webpage the information should besubdivided more clearly into working areas sothat potential clients can find the requesteddata more easily: specific data for coaters,fabricators, engineering offices etc. should beclustered. In Mr. Driesch’s opinion the TensiNet Association should formulatenew goals to develop appropriate solutionslike for recycling PES/PVC-fabrics.

Heidrun Bögner-Balz

h.boegner@labor-blum.de

www.labor-blum.de

The regional TensiNetMeeting organized onMarch 2nd 2006 was a success. About 30 experts representingaround 20 organismsand firms attended themeeting. Prof. Llorensgave a lecture aboutthe evolution of tensilearchitecture in Spainand Portugal in the lastfew decades, and Juan

Monjo Carrió explainedthat TensiNet wasfunded to be acollaborative Europeanventure. The interest ofthe current TensiNetAssociation wasclarified. Other topicsof discussion were theorganization of the“Iberica branch”, anIberian section on theTensiNet website, the

organization ofseminars andworkshops to be heldin 2007, and thetranslation of theDesign Guide.There was a goodfeeling and nextmeetings areprogrammed to takeplace in Barcelona inApril and in Madrid inJune to take final

decisions aboutentering the TensiNetAssociation andorganizing the “Ibericabranch”. Even an“Ibero-americanbranch” wasconsidered.

Juan Monjo Carrió

director.ietcc@csic.esJosep Llorens

Ignasi.Llorens@upc.edu

Working Group for Textile Architecture: Meeting Frankfurt 19th October 2005

Regional TensiNet Meeting in Madrid, Spain

ForthcomingEvents

ROOF & CLADDINGMIDDLE EAST 2006

International symposium

Expo Centre, Sharjah,United Arab Emirates

02/05/2006> 04/05/2006

www.roofmiddleeast.com

TEXTILE ROOFS 2006Workshop

Berlin, Germany

25/05/2006> 27/05/2006

www.textile-roofs.de

ADAPTABLES 2006International Symposium

Eindhoven, The Netherlands

02/07/2006 > 05/07/2006

www.supertuesday.tue.nl/adaptables2006.htm

IASS / APCS 2006International Symposium

Beijing, China

16/10/2006 > 19/10/2006

www.iass2006.cn

TENSINET-SYMPOSIUM 2007

International Symposium

Milan, Italy

16/04/2007 > 18/04/2007

www.tensinet.com

TECHTEXTILFRANKFURT 2007

Trade FairFrankfurt, Germany

12/06/2007 > 14/06/2007

www.techtextil.messefrankfurt.com/frankfurt/en/home.html

STRUCTURALMEMBRANES 2007

International Symposium

Barcelona, Spain

17/09/2007 > 19/09/2007

http://congress.cimne.upc.es/membranes07

The functioncooltrax® is a high-tenacity netfabric with a unique triangulargeometry. When the sun shinesthis structure creates light andshadow fields on the groundthat move constantly due toearth rotation. So heataccumulation on the ground isprevented. The specialtriangular geometry is the onlypattern ensuring that eachpoint is evenly shaded. Thussun or shadow stripes arecompletely avoided withoutregard to the material’s angleto the sun. This means aperfect half shadow.

The advantagescooltrax® withstands high windloads and only requires light constructions. It offers a maximumcooling effect due to the material structure which has 32% of opensurface. This prevents heat accumulation underneath. cooltrax®

reduces rain noise on dormer windows and sky lights and protects thewindow material against e.g. hail. When used indoors cooltrax® issuitable for sprinkler systems.

The application areasAt home the shading materiallets the light in, but keeps theheat outside. Hence it can beused for sun parlours/wintergardens, dormer windows/attic windows,terraces/patios and balconiesas well as for carports.Shading can also be neededin business buildings in open-plan offices, conferencerooms, vestibules, light streetsor glassy airport halls.The shading material is alsoappropriate for leisure timecanopies over sandpits in thedomestic garden, places atthe beach, sun lounges by thepool, children’s paddlingpools, camping sites, etc.

The coated mesh can be used for sun shields on a bigger scale like formarket places, street cafes, school yards, kinder gardens andplaygrounds as well as for fields for tennis, football/soccer, golf andathletics.

heytex® cooltrax® this name stands for a whole new way to enjoy the sun in the shade and for shading places

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Close-up of the cooltrax® shading material

Booth in cooltrax® material, Gartenlust & Landvergnügen, Ippenburg

Test results (temperatures in function of the time of the day) for testing boxes placed on pavement with closed sides in the climatic zone of Casablanca

Katrin von Dreele: kvondreele@heytex.com • www.heytex.com

THE INTELLIGENT SHADING MATERIAL

Base fabric W/F (DIN ISO 2076) trade mark polyesterYarn W/F (DIN 53830) meshwork 550 dtex,

triangular fields 167 dtexBase cloth weight (g/m2) (DIN 53854) ca. 150 g/m2

Coating material PVCTotal weight (g/m2) (DIN 53352) ~480 g/m2

Tensile strength (N/5 cm) (DIN 53354) 850/550Elongation at break W/F ~22%/21%Thickness ~0.9-0.95 mmWelding adhesion at least 100 N/5 cmLight fastness grade 7Flame retardancy (DIN 4102 Teil 1) B1 burning dropletsAir resistance coefficientCw (DIN 1955) 1.054Total strength coefficient Cg 0.818

The Munich and London based design firm ‘Architecture and Vision’presents a new design and prototype for a one-person tent to be usedin the extreme temperatures of the desert. The inflatable tent is theresult of a study performed for the European Space AgencyTechnology Transfer Programme and employs several conceptsdiscussed in Space Exploration. The prototype has beenmanufactured by Italian aerospace company Aero Sekur S.p.A.

The structure is making use ofthe specific temperature curve inhot arid regions, where the air isgetting considerably cooler themore distant it is from theearth’s surface. This effect isused by many desert animals likethe camel.

The tent has recently been in the exhibition “SAFE: Design Takes OnRisk” from October 2005 until January 2006 at The Museum ofModern Art (MoMA) in New York. It will be shown this summer in theMuseum of Science & Industry in Chicago in the special exhibition“Leonardo da Vinci: Man, Inventor, Genius”.

Model at the exhibition “SAFE: Design Takes

On Risk” at The Museum of Modern Art

Desert Seal is an inflatableone-person tent for hotextreme environments. Theintroduction of a verticalelement allows a high air-intake for cooling the tentinside. In addition it allowsentering the tent upright andtaking the cloth of inside,protected from wind. Theentrance can be opened andclosed by a zipper.

To create the vertical element an air beam construction has beenchosen to allow a dense packaging and lightweight construction. Theair beams form a vertical A-frame, which ends in an aluminium plate,which allows a stand-off for the air-intake. Between these air beams asilver-coated awning is spanned to form an anti-clastic shape. Thisprovides an elegant transition fromvertical to horizontal as well as aflutter-free spanned textilesurface, which offers goodaerodynamics with a low wind-resistance.

The first prototype has beenmanufactured by the Italianaerospace company Aero SekurS.p.A. (www.aerosekur.com),specialised in parachutes and life-saver inflatables. The tent consists of an air beam structure made ofyellow PU-coated polyethylene fibre. The two V-shaped air beams arekept on distance by another air beam at the widest part of the tent. Atthe top and bottom end they are held by an aluminium plate, whichdefines an end and allow the openings for the airflow.

The awning is a silver-coated high-strength textile to reflect heat andprotect from direct sunshine. The awning is seamed together out offour pre-cut pieces and glued directly onto the air beam to allow aneasy set-up also in strong winds. In its longitudinal axis the tent isfixed to the ground from both ends by ropes and two large plastictent pegs, which allow fixation in the sand, but also in other grounds.The A-frame provides lateral stability.

The tent design follows twobaseline strategies to protectagainst the excessive heat in thedesert. First, it is providing apassive sun protection by heatreflective shading material andsecond, it is making use of in-

situ resources. In the desert, where the balancing plant cover ismissing, the ground heats up very quickly by the radiation of the sun.The fact that air is actually a good insulator, prevents it from heatingup as much and as fast as the ground. In fact, the air becomesconsiderably cooler the more distant it is from the Earth’s surface.During the day, the temperature can easily reach 60°C and beyond atground level, while just 2-3 meters above, it can be up to 40°C lower.This characteristic is used to cool the tent. Water based coolingtechnologies would have a high weight penalty, whereas others wouldrequire a lot of energy.During the day, an electric fan in the top of the tent, 2.26 m above theground, constantly blows cooler air into the tent, thus reducing theinterior temperature. The fan is powered by batteries charged by aflexible solar panel mounted outside the tent. This rollable solar panelis a development by the Swiss company VHF-Technologies. Batteriesare standard AA rechargeable batteries.During the night, the desert ground radiates heat off to space and isquickly reaching temperatures below zero °C. Since air is acting againas a good insulator, it stays considerably warmer on higher levels. Thistemperature inversion now allows to collect warmer air, using thesame principle. The fan on top is now running on batteries andblowing warmer air into the tent, protecting from the cold air atground level. This environmental condition in the desert is not only used by animalsto fulfil their cooling requirements, but is also employed sincecenturies by traditional building know-how. In Iran, for example, manyold buildings have so called ‘wind-towers’, where the cool air isscooped and led down a chimney into the building.

Recent and near-futuredevelopments in battery andsolar-panel technologyincreasingly allow new conceptsalso in mobile structures, which

Diagram showing the temperature curve inrelation to the distance of the ground in the desert

Picture from inside the tent, showing the airoutlet at the bottom end

Picture from inside the tent showing the electricfan on top of the tent and the two air beamsforming the vertical A-frame structure

Front and side elevations of the Desert Seal tent

DESERT SEALA Tent with active Cooling

Andreas Vogler and Arturo Vittori •

http://www.architectureandvision.com

The Desert Seal tent set up with the flexiblesolar panel installed. The silver metal coatedawning is reflecting the heat from the sun

View of Desert Seal with the flexible solar panelinstalled

4

New tensioning system for textile façadesBuitink Technology has developed and patented an innovative system

to tension textile façades and membranes: an inflatable tensioning tube

5

even a few years earlier wouldhave been easily dismissed,since the technology wouldnot have met therequirements. The tent packstightly into a backpack andweighs less than sixkilograms. The beauty of thisstructure derives from itsfunctionality and efficiency,particularly dealing with suchnatural energies as sun andwind. The aerospacearchitecture background ofthe designers is visible in theconception, construction andmaterialisation of the project,using natural resources andminimum weight fortransportability. Desert Seal’s‘down-to-earth’ conceptderives from currentlydiscussed Space Explorationconcepts. A smalltransportation volume, largedeployment volume and alight-weight construction arecrucial for all spacecraft.Inflatables have beenanticipated from the verybeginning of space flight andare considered for HumanHabitats on Moon and Mars.The temperature extremes ofSpace are also found onEarth and the use of localenergies (In-situ ResourceUtilisation) for coolingand/or heating is reducingtransportation mass. HumanSpaceflight is relying onactively controlledenvironmental systems. The energy needed to drivethe small electric fan isgained by a light-weightflexible Solar Panel, atechnology also tested forspaceflight. Thermal controlis one of the key points indesigning space structures.Desert Seal exploits severalconcepts used in the spacethermal control systems. Thealuminised fabric used for thetent cover is very similar tothe Multi Layer Insulation(MLI) used for spacecraft.

The Desert Seal tent can be packed denslyand is quickly deployed by a pump

All pictures: © Architecture+Vision

Visualisation of textile façade

Examples of detail

Working principle of tensioning system

Working principle of tensioningsystem

Test set-up

Textile façade When a fabric is used to create a textile façade at the exterior of a building, onehas to take into account (large) wind forces. Especially above 10-20m and incase the textile façade is installed at more than 15cm away from the building(which means no or less pressure compensation), the forces on the fabric will belarge. In these cases a once-only pre-tensioning of the membranes might not besufficient, especially when façades for the long term (permanent) are installed.

Existing tensioning systems By tensioning the panels with a spring system, larger forces can be taken by thefabric, to provide tension and to give the fabric the possibility to deform to acertain extent. This can be done by fixing the panels to a (aluminium)tensioning tube or by providing the fabric with springs or elastic rope. Thesesystems have some disadvantages. Springs and elastic rope will wear in timeand will have to be replaced. A tensioning tube needs periodic maintenanceand lubrication. Besides, it needs a very precise and controllable measuring andtensioning (also in the long term) of the tubes and fabric. Maintenance andreplacement of parts will often have to take place in areas that are difficult toreach. Further, when using springs or elastic rope, space will remain betweenthe fixation points to the façade and the fabric panels. Also the fixation partswill remain visible. Finally, an aluminium tensioning tube is rigid and notflexible, which can make it difficult to introduce forces into the fabric evenly.When e.g. one fabric panel covers the complete width of a façade and is fixedto aluminium tensioning tubes, the wind forces on the panel will vary ondifferent locations of the fabric panel (at the corners there will be probablymore force than in the middle).

New: Buitink inflatable tensioning tube In addition to existing tension systems and to take away some majordisadvantages, Buitink Technology developed a new tensioning system: theflexible, inflatable tensioning tube. The system consists of an inflatable tube towhich the fabric panels are connected, by means of e.g. a weld or connectionprofile. By inflating the tube, the fabric is tensioned like a spring system. In caseof external forces, the fabric will tend to deform and will therefore need extralength. This length is obtained by deformation of the round tube into a moreoval shape. Depending on the diameter of the inflatable tube and the innerpressure, this will result in an opposite resulting pulling force from the tube,which keeps the fabric tensioned and will bring it back to the original state. A simple and central air unit maintains the system of inflatable tubes.

Advantages of the inflatable tensioning tube The inflatable tensioning tube has a number of major advantages. First of all,the tubes need no or hardly any maintenance. The only maintenance will haveto take place at the central air unit (e.g. a yearly inspection), which basically isthe complete tensioning system. Besides, architects have more freedom indesign, since the tube can be installed out of sight and the fabric can beconnected directly on the façade (without having space between the fabricpanels and the fixations for the springs or elastic rope). Further, differentcombinations of diameter, inner pressure and maximum deformation can bechosen. Moreover, the inflatable tubes will provide for stiffness perpendicularto the tensioning direction but at the same time they will remain flexible andbendable. This way, external forces can be introduced into the fabric panels ina more evenly way than in case of a rigid tensioning tube. Finally, it is easy togive the tubes on a higher level on the façade more inner pressure, to takelarger wind loads (the tensioning properties can be adapted to localcircumstances). A short summary of the advantages: freedom of design anddetailing, tensioning of flat fabric panels possible, maintenance only at the airsystem, many possibilities of application, and evenly introduction of forces.

A large number of applications….. The system with inflatable tensioning tubes can be used for a lot moreapplications, like tensioned ceilings, banners, tents and even trampolines!

Rienk de Vries: info@buitink-technology.com • www.buitink-technology.com

Chemically Rigidized Expandable Structures (CRES) for Space Application

BackgroundBetween 1979 and 1992, underEuropean Space Agency (ESA)contracts, Contraves AG (Zurich,Switzerland) undertook todevelop a technology forinflatable space rigidizedstructures (ISRS) — intended toserve a wide range of spaceapplications — that raised interestbeyond the original sponsor, e.g.of researchers in the US and inJapan. Unfortunately, thissomewhat unconventionaltechnology could not obtain theflight opportunity that it neededto prove itself in a real testenvironment, leading the Swisscompany to abandon activedevelopment early in the 1990sthen, ten years later, to whollywithdraw from the field. In themeantime, ESA has restarted aneffort in this technologicaldomain. Dr. Bernasconi had the privilegeto become involved with thiswork at its very onset (when hewas massively involved both inthe technology definition and inthe design of the first reflectors)and to accompany it through itsexpansion phase. Because of hiscompetence, in the 1990s hebecame the sole point of contactfor the ISRS field, and performeda number of studies and

assessments for interested thirdparties. Since Contravesdisclaimed any further interest, hehas continued to offer hisengineering services and hisexpertise about inflatableexpandable structures, doingbusiness under the firm of «MCBernasconi Consultants» (MCBC,for short) since January 2003.Below, we summarize some of thepast activities related to the threeclasses of applications: precisionstructures, backbones, and heavy-duty items.

Precision StructuresFor historical reasons, work atContraves centered on microwaveantenna reflectors, whosedifferent forms find numeroususes in communications,astrophysical research, andremote sensing.

Reflectors for CommunicationsAntennae & Radio TelescopesThe experimental activities atContraves led to the manufactureof some eight complete parabolicreflectors, with apertures rangingfrom 1 to 10 m. Three early scalemodels of a symmetric (center-fed) reflector were used toappraise issues such as foldingand deployment, manufactureprocesses, and achievableaccuracy. In successive phases,

the first-ever "inflatable" offsetreflector was built, with three 3 mobjects used for extensive tests,collecting data on accuracy (0.7 mm root-mean-square (rms)for the last object manufactured)and electrical performance --measured at frequencies up to 22 GHz on an object (Figure 2)folded, re-deployed, and cured.Also tested were the concept'shigh packaging efficiency (Figure1), its controlled deployment invacuum, and the chemicalrigidization under simulatedspace conditions. Successively, a10 m aperture, offset-fedreflector designed for multi-beamoperation at 1.6 GHz wasmanufactured and tested (underclean-room conditions -- Figure 3):while the initial 2.2 mm rmssurface error grew to 2.7 mm rmsafter folding and deployment, thereflector still kept a side lobe levelof -33.8 dB.Most communications antennaeadopt offset-fed configurations,to minimize interferences: inradio astronomy, where issues ofgain and resolution predominate,symmetric (on-axis) designs aremore common. Investigating theQUASAT orbital radio telescope, a European scientific groupsuggested to base it on CREStechnology. Supporting activities

at Contraves culminated in themanufacture and test of a 6 mdiameter Test Article (Figure 4)(1.2 mm rms). Further, weprovided assessments andsupport for scientific projects(e.g. Radioastron, the MODESTconcept) and, following upvarious external queries, weevolved a self-contained,compactly stowed, reflectorconcept, to create relatively largeapertures (up to 6 m) to small-satellite missions.

Solar ConcentratorsHigh-concentration-ratio solarcollectors represented a pre-eminent application forflexible wall structures. A study ofa Solar-Thermal Upper Stage (Figure 5), led by EADS SpaceTransportation, offered theopportunity to assess the interestof continuously inflated reflectorsfor such an application, as thelimited life time (up to a month)of such a system makes the use ofthis technology possible.

Backbone StructuresTo satisfy their functions,precision structures demandextended design, analysis, and in-process control measures, butthey do build on a technologybase that allows realization ofbearing elements without

Figure 1: A typical deployment sequence of an inflatable offset reflector demonstrated with “LOAD-3-1” - the first ever rigidizable offset reflector (on the floor ofContraves’ 10000-class clean room). ©Contraves AG (1984)

Figure 3: LOAD-10 offset reflector at the end of manufacture ©Contraves AG (1990)

Figure 4: 6 m Test Article for the QUASAT radio telescope reflector (nominally at 1/3 scale) within Contraves Space 100000-class clean room.

©Contraves AG (1988)

Figure 5: LH2 solar-thermal stage featuring apair of solar concentrators relying on inflatablecollectors for the first stage, with CPC elementsas second stage.

©EADS-ST (2001)

Figure 2: The 3 m ISRSoffset antenna asused for far-field RFmeasurements,with feedsand support

structure byCSELT, Turin

©CSELT (1986)

6

7

inherent accuracy requirements.Thus, lightweight backbonesseem the logical objects to beginimplementing a CRES capability,as ESA and industry areattempting today. Analysesshowed that -- even with simplemorphologies -- the technology'sversatility in complying withvarious needs, still reachesnumerous prospective users.

Planar Instrument Carriers &Solar SailingAny CRES item has an overhead(container, pressure-controlitems, etc) that may become tooimportant when used on a "toosmall" object with "too simple" afunction. As a torus replacesseveral linear elements, suchframes return a better value forthe investment overhead. Anddesigns where a toroidalstructure deploys and supports aflat membrane can suit to a widerange of tasks. In particular, solarsails have been assessed in anumber of studies (Figure 6): thetorus design remains attractivefor such uses up to some 100 min diameter. Toroidal supportstructures received attention for apower transmission rectenna, aswell as for thin-film photovoltaicsolar arrays (TFPV -- Figure 7). To date, no such object has beenbuilt in Europe, but experienceexists both with more complexitems (as used within the FIRSTshield model, mentioned belowand including rings of 3.5-4 m,each incorporating 12 nodes),and with purely inflatable, butlarger (6-15 m), stabilization toriwithin antenna reflectors.

Single-Tier Structures: Aero brakes and moreAs the flexible parts grow to asignificant size, it appearsindicated to position thespacecraft body in the frame by atripod connection (or one with 4,5, or 6 legs). Single-tier elementscan deploy lightweight aerobrakes (e.g. to lower a piggybacksatellite's orbit, or to accelerate aspacecraft's end-of-life decayfrom orbit), to support shadow

shields or «instrumented»membranes (microstrip, lens or reflectarray antenna elements;sensors or multifunctionaldevices, etc). Our studies have shown the attractiveness of such anoption for (slow) aero braking,both in terms of mass and costs (Figure 8).

Two-tier Structures: Telescopes'Tubes and Thermal ShieldsMastering the creation of nodesconnecting out-of-plane tubes toa flat frame enables the creationof 3-dimensional assemblies,complex truss works andpolyhedral skeletons. The initialscientific proposal for a FarInfrared Space Telescope (FIRST)foresaw an 8 m mirror, radiativelycooled to 150 K, thus requiringan expandable thermal shield inthe 10 m size range, for which itsuggested a CRES object. Wedefined this shield as a two-tierassembly, with 48 cylindrical strutelements joined at 24 nodes, eachinterfacing with either four orthree struts. Several ESTECcontracts supported the work atContraves, including the manu-facture of a complete 3.5 mskeleton (Figure 9), used forpackaging, deployment, cure, andgeometric check activities.

Expandable space structures nomore complex than this can covermany applications – includinghangars and other unpressurizedenclosures. In their basic form,orbital hangars build anenclosure for shielding astronautsand hardware duringmaintenance and repair activities,adding services like controlledlighting, some thermalconditioning, work stations andmore. Shielding cryogenic upperstages appears an engineeringapplication viable for a FIRST-shield level technology. Also, theuse of inflatable structures forrealizing greenhouses, particularlyoperating on planetary surfaces,has been discussed and currentlyreceives an increasing amount ofattention.

Heavy-duty Structuresfor HabitationExpandable, habitable volumesembody an ambitious use ofmembrane structures technology.In 2001, the Italian Space Agency(ASI) sponsored the firstEuropean study in this direction,in which Dr. Bernasconiconsulted for Oerlikon-ContravesItaliana (Rome). In analyzing thepackaging of flexible-wallhabitats of different basicgeometries, he showed that botha full torus and its C-annulusderivative (Figure 11) are mostconvenient in terms of theachievable expansion ratio -- i.e. the ratio of the volume of thestructure expanded to its volumestowed. A recommendedmodification of theconfiguration "A" habitat (Figure10), complying with a 4.7 mhigh, 4 m diameter stowagevolume, would increase theexpansion ratio (from 4.5 to 5.9)and thus the habitat's volume(225 m3 vs 135 m3).If expandable habitats offer acapacity well beyond thatotherwise compatible with atransportation systems, they raisethe problem of furnishing them.To create secondary internalstructures, one can use eitherconventional, rigid, equipment --that has to pass through airlocksand hatches connecting withdistinct carriers in a timeconsuming way -- or foldingelements. MCBC, as part of theHTS (Zurich) team, hasaddressed the type and layout ofauxiliary structures that the«Space Haven» module (understudy at Alenia Spazio) wouldneed. But this remains an areafor much future work.

http://esprist.bathome.org • Dr Bernasconi, mcbc1@bathome.org

MCB Consultants bring the accumulated expertise of the pioneering work at Contraves AG into current and future developments

Figure 6: Frames andPICs (Planar InstrumentCarriers): the concept ofa solar sailing spacecraftfor asteroid exploration,with four 2500 m2

saillets. ©MCBC (1995)

Figure 7: Concept for a toroidal support frame(PIC) for a thin-film photovoltaic array.

©MCBC (2004)

Figure 9: The 1/3-scale model of the ISRSskeleton for the FIRST’s thermal shield.

©Contraves AG (1990)

Figure 8: Single-tierskeletons, such as could be used e.g. on smallsatellites to form a light-weight aerobrake, or tosupport a reflectarrayantenna or a lenscollector.©Contraves AG (1990)

Client European Space Agency (ESA), ESTEC, The Netherlands

Original contractor Contraves AG, Zurich, SwitzerlandEngineer MCBCMaterials Textile composite of Kevlar with a modified

cycloaliphatic epoxy resinExecution 1980 - 1991

Figure 10: An inflatableorbital habitatinvestigated during the SpeS Study

©IACSA/Ing. Speranza (2001)

Figure 11: AC-annulus shell in cross section.©MCBC (2004)

In the beam theory one finds theexpression E J as the bendingstiffness in the differentialequation for the displacement w:

M is the bending moment, E isthe E-modulus of the materialand J is the axial momentum ofinertia of the cross section.Analogue equations are valid forthe displacement of plates. In thetheory of membranes such anexpression for the stiffness is notyet known. The question rises: canone define an analogue expres-sion for the membrane stiffness?

Approximate theory of membrane deformationand stress distributionTo get an expression for themembrane stiffness one startswith the equilibrium conditionsfor a prestressed membrane.Assuming a covariantformulation, these conditionshave the form:

Here N is the stress tensor withthe contravariant componentsNαβ. Bαβ are the covariantcomponents of the curvaturetensor. In the pre-stress state oneassumes the load p to zero, andobtains an anticlastic surfacewith a negative Gaussiancurvature. The stresses here maybe nαβ and the curvature bαβ inthe homogeneous equilibriumconditions

Under a loading p perpendicularto the membrane surface thestress will change from the pre-stress nαβ to the Nαβ and thecurvature will change from bαβ toBαβ :

Setting these expressions into theequation above and neglectingexpressions of order two one gets:

For the change of curvature ∆bαβone gets a linear approximationin function of the displacementsu in perpendicular direction:

Here the suffixes indicate thesecond covariant derivative of u. For the changes ∆nαβ one canwrite a linear elasticapproximation:

The Εαβγδ are the components ofthe tensor of rank four ofelasticity and the εγδ are thecomponents of the tensor ofdeformations. For a two-dimensional orthotropic materialΕαβγδ has the following form:

Ε1111 is the stiffness in the warpdirection. Ε2222 is the stiffness inthe weft direction. Ε1122describes the influence ofPoisson ratio. Ε1212 is the shearmodulus. For the deformation εγδ one canassume when neglecting the non-linear terms and theinfluence of the tangentialdisplacements:

Thus one gets the following ex-pression for the displacement u

where D is called the membranestiffness:

Partial solutionIf the load does not change overthe surface and if the initialcurvature is almost constant, a particular solution of thisequation may be written as

Interpreting this, one mayunderstand that D is themembrane stiffness. Thisstiffness has the form:

One can easily prove that D ispositive if the determinant of thestiffness tensor is positive. The physical dimension of D is force/length3.Using this expression for u, one gets for the change of thestresses under a load p in thisapproximation:

Now one may use the possibilityof scaling the tensor of thematerial stiffness by dividing it bythe highest stiffness, say E1111 =E, further called the scalingfactor or magnitude of theelastic moduli. Then one gets:

with the abbreviations:

Using this one gets

D can be composed as a productout of two parts: one part E,which indicates the magnitude ofthe elastic moduli, and one part ∆, which describes theinfluences of curvature andanisotropy. The part ∆ is oforder two in curvature. The deflection u now may be written as:

The deflection is indirectproportional to ∆ and E, and thus indirect proportional to the square of the curvature.The increment of stress results in:

The increment of stress isindependent of the magnitude of the elastic moduli E, butindirect proportional to thecurvature. These conclusions arevalid for the case that the valueof D is high enough. If u is aparticular solution of the

equilibrium conditions it is tostate that u does not fulfil anyboundary condition. But then ageneral solution can be writtenas the sum of this particularsolution and a solution of thehomogeneous equation:

When neglecting the tangentialdisplacements and assuming theboundary of the problem to beparallel to the x2-coordinate andx1 orthogonal to this boundary,the solution for the homo-geneous part along thisboundary is:

The total solution will be:

The condition u = 0 for x1 = 0leads to:

Thus the solution will be

along the boundary x2 = 0.

To clarify these results, D and thestatic properties under pressureload will be calculated for twocases with finite element models.Here, the approximationsmentioned above are notapplied; the deflections in thetangential direction are takeninto account.

Case study 1Assume a hyperboloid of thefollowing form:

The covariant components of thetensor of curvature can becalculated to be:

The size of the surface is 20m x 20m projected on the x1-x2-plane. Assume first that warp and weftare approximately in thedirections of the generating

8

The mechanical behaviour of coated fabrics and films used in prestressed textile engineering: Its importance in the analysis and how to derive membranestiffness by simple theoretic considerations

áâ 0//

straight lines. Then themembrane stiffness D results in:

where C is the elevation and G isthe determinant of the metrictensor:

The term E1212 is approximately300 kN/m. Thus D will berelatively small and the stressesdependent of the magnitude ofthe elastic moduli E.The values for the physicalcomponents are assumed to be:

The load p is considered to be250 N/m2. (figure 1)

In figure 2 the maximaldisplacement u in normaldirection is shown as a functionof the magnitude of the elasticmoduli E.

The curves plotted differ inelevation of the hyperboloid, or, in other words, with thecurvature: the higher thecurvature, the lower thedisplacement. The dependenceon the modulus resembles a

hyperbola as predicted by the theory, although the stiffness D is very low. There is no difference betweenthe principal behaviour for high and low curvature,respectively C.

In figure 3 the maximal stress inwarp direction is presented infunction of the magnitude of theelastic moduli E. Once more thecurves differ in the curvature Cof the hyperboloid: the lowestone belongs to the largestcurvature.

Here the conclusion derivedabove does not work: one sees aremarkable increment of themaximal stress with the scalingfactor E.

Case study 2The same shape is used but themain axes of anisotropy areoriented along the diagonal ofthe surface. The covariantcomponents of the tensor ofcurvature along these axes are:(figure 4)

Here the membrane stiffness Dresults in:

This value of D is higher because the stiffness in warp and weft direction is in the orderof MN/m.

Figure 5 represents the maximaldeflection as a function of the magnitude of the elasticmoduli E. The single curvesdiffer in curvature C: the uppercurve belongs quite clear to the lowest C, the lower one to the largest C. The hyperbolicbehaviour is quite evident.

Figure 6 presents the maximalstress in the warp direction as a function of the magnitudeof the elastic moduli E for different curvatures C.

For C = 0.1 the stresses dependon E but form C = 0.3 thisdependence disappears with increasing C. For higher curvatures, the maximal stress does notdepend on the scaling factor E,or, in other words, on the magnitude of the elasticmoduli E. That is why the E-moduli are asked only veryroughly from the design people.But since lately, the preferreddesign of the structures becomesmore and more flat, the precisevalue of the E-moduli willbecome necessary.

Conclusion

1. It is possible to define amembrane stiffness D whichreflects the materialtangential stiffness tensorand the influence ofcurvature.

2. If D is large enough theincrease of stress undernormal loads does notdepend on the stiffness itself. One has not to knowthe stiffness matrix veryexactly.

3. Under constant normal load one can find analgebraic particular solutionof the equilibrium conditionswhich do not fulfil theboundary conditions.

4. The deflection under normalloads depends from thestiffness.

5. If D is low the stress increaseunder normal loads dependson the stiffness. One has toknow the stiffness matrixexactly.

AcknowledgementsThe numeric analysis for theexamples of this paper was doneby K. Reimann and M. Jentschusing the programming system/7/, /8/, /9/

Rainer Blum

r.blum@labor-blum.de

Heidrun Bögner-Balz

h.boegner@labor-blum.de

www.labor-blum.de

REFERENCES[1] Bidmon, W. und Blum, R., Spannungs-

Dehnungs-Verhalten von BautextilienSFB 64 Mitteilung 74, 1987

[2] Blum, R., Beitrag zur nichtlinearen Mem-brantheorie, SFB 64 Mitteilungen 73,1985

[3] Bögner, H., Vorgespannte Konstruktionenaus beschichteten Geweben und Rolle desSchubverhaltens bei der Bildung von zweifachgekrümmten Flächen aus ebenen Streifen,Dissertation Stuttgart, 2004

[4] Meffert, B., Mechanische EigenschaftenPVC-beschichteter Polyestergewebe,Dissertation Aachen, 1978

[5] Blum, R.; Bögner, H.: Evaluation method for the Elastic Moduli,Tensinews Newsletter 3, Internet-publication 2002

[6] Blum, R.; Bögner, H.; Némoz, G.:Material properties and testing, in European Design Guide for TensileSurface Structures, Brussels 2004

[7] K. Reimann and M. Jentsch:

“Numerische Berechnung und Visualisierungdes Spannungs-Dehnungs-Verhaltens vonGeweben mit SCOOP-BB”, FemScopeGmbH, 2005.

[8] K. Reimann and M. Jentsch: “Object-oriented Analysis of Textile Structures usingthe SCOOP Framework”. ECCOMASStructural Membranes 2005.

[9] M. Jentsch, K. Reimann, R.Wagner andS. Rudolph: “Innovative Design ofMembrane Structures”. ECCOMASStructural Membranes 2005.

9

αβγδ

Figure 1. Saddle shaped surface with orientation of the main axesof anisotropy parallel to the boundaries

Figure 4. Saddle shaped surface with orientation of the main axesof anisotropy rotated 45°

Figure 2: Maximal deflection u as a function of E for increasingcurvature C

Figure 5: Maximal deflection u as a function of E for increasingcurvature C

Figure 3: Maximal stress as function of E for increasing curvature C

Stre

sses

s in

kN

/m

Figure 6: Maximal stresses as a function of the scaling factor E forincreasing curvature C

CASE STUDY 1CASE STUDY 1

CASE STUDY 2

Def

lect

ion

in m

Scaling Factor E in MN/m

Increasing curvature C

Max

imal

str

esse

ss in

kN

/m

Scaling Factor E in MN/m

Increasing curvature

Def

lect

ion

in m

Scaling Factor E in MN/m

Increasing C

Scaling Factor E in MN/m

Increasing C

TEXTILE ROOFS 200611TH INTERNATIONAL WORKSHOP ON THE DESIGN AND PRACTICAL REALISATION OFARCHITECTURAL MEMBRANE STRUCTURES TU BERLIN MAY 25TH – 27TH 2006

ObjectivesThe workshop’s objectives are toprovide fundamental practicalinformation, as well aspresenting the state-of-the-art intextile roof engineering know-how. In addition to acomprehensive programme ofpresentations in English by keyfigures from the membranestructure industry, a uniqueopportunity for the study andhands-on development ofpractical case-studies in aninformal tutorial environmentwill be provided. Above all, theworkshop aims to providepractical answers to real-worldquestions.

IntroductionIn the last eleven years, tenworkshops on the Design andRealisation of Textile Roofs wereheld in Berlin. Due to thepractical emphasis and uniqueformat, these events have provento be increasingly popular.Textile Roofs is now anestablished annual event. The 2005 workshop (reportsavailable at http://www.tensinet.com, in the librarysection) attracted around eightyparticipants from twentycountries. The series willcontinue in 2006 with furtherdevelopments and enhance-ments to the programme.The workshops are concernedwith the design of architecturalmembrane roof structures. Formost people such roofs aretypified by world famous sportsstadia and temporary expositionstructures. Although prestigiousbuildings of this type continueto utilize tensile roofing systems,the scope of application has

widened considerably over thepast decade. Today, tensile roofsare routinely used in shoppingcentres, corporate headquarters,leisure centres, zoos, schools,and even factories. With acombination of visuallydramatic curvilinear forms, andeconomic efficiency, sucharchitectural solutions representan attractive option for manysituations.The participants to the previousevents have come from a widerange of backgrounds, rangingfrom established experts tocomplete novice students. Thisrich mix appears to explain partof the popularity of theworkshops.

Programme and LecturersThe detailed programme may befound at the workshop’swebsite.In addition to a comprehensiveseries of lectures presented inEnglish by key figures from themembrane structure industryand academia, opportunity forthe hands-on development ofpractical case-studies in aninformal tutorial environmentwill be provided. The followingkey subjects will be addressedduring extended morninglectures:· Introducing Lightweight

Structures· Computational and Physical

Modelling · Project Management and the

Design Process· Detailing, Connection Design

and Fabrication · Project Case Studies · Materials for Textile Structures · Environmental Aspects

During each afternoon, thehands-on workshop will runwith opportunities for bothcomputational and physicalmodelling. In parallel to thispractical activity, specializedlectures will be presented onstate-of-the-art topics for themore advanced participants.

Students SeminarThis year, an InternationalStudents Seminar held fromMay 23th – 27th is part ofTextile Roofs 2006. Selectedstudents with different fields ofstudy and great interest intensioned structures, have thechance to develop a sense forthese structures by practicalexperience. Finally, they will havethe possibility to discuss theirwork with the participants andprofessionals of the workshop.

SponsorsIn addition to the TechnicalUniversity Berlin, Textile Roofs 2006 is supportedby technet GmbH(www.technet-gmbh.com),Ferrari (www.ferrari-textiles.com) and TensiNet(www.tensinet.com).

Prof Dr. Ing. Lothar Gründig,

gruendig@inge3.bv.tu-berlin.de

www.textile-roofs.de

Model built by Elisa Gutierrez Pneumatic construction by Matti Orpana, Tensotech

10

Architextiles explores thecontemporary intersectionsbetween architectural and textiledesign. Focusing on thepossibilities for architectural andurban design, this issue examinesthe most generative set ofconcepts, forms, patterns,materials, processes,technologies, and practices thatare driving the proliferation ofthis multi-disciplinary designhybrid.

Architextiles represents atransition stage in spatialdesign's re-orientation towards amore networked, dynamic,interactive, multi-functional, andcommunicative state. Theparadigms of fashion and textiledesign, with their unique,accelerated aesthetics, andability to embody a burgeoning,composite, and complex rangeof properties such as lightness,flow, flexibility, surfacecomplexity, and movement, havea natural affinity witharchitecture's shifts towards amore liquid state. Theemergence of Architextiles toarchitectural prominencechallenges traditionalperceptions and practices ofinteriors, architectural, urban,landscape, and fashion andtextiles. Interweaving newdesigns and speculative projectson the future, Architextilesbrings together architects,designers, engineers,technologists, theorists, andmaterial researchers to unravelthese new methodologies offabricating space.

Each of the contributors offers aunique insight into thedimensions of Architextiles. Thistitle includes the work of NigelCoates, Dagmar Richter, LarsSpuybroek, Frederic Migayrou,Peter Testa, Dominique Perrault,Kennedy & Violich, DavidWakefield, Bradley Quinn,Robert Kronenburg, Will Alsop,Matilda McQuaid, UshidaFindlay, Marie O'Mahoney,SHoP, Arup, Tensys,Massimiliano Fuksas, and newprojects and writings fromyoung and emerging designersand theorists.

LITERATUREby M.G. Garcia

Architextiles

Paperback: 128 pages Publisher: Wiley-Academy , Nov 2006

ISBN: 0470026340

D E - L I G H T A N D A I RTOPIC

Even today, tensioned andinflated membranes are stillfascinating. This fascination isbased on the relation of the freeshaped tensioned structures tonature, and depends on theorganic shapes, the lightness andtransparency of textile buildings.Like in nature, the shapes ofmembrane structures are lessdetermined by the designpurpose, and are quite a bitmore influenced by the processof development.Non-tensioned membranes andcables are slack, and can berolled, or folded up, and onlytensioned or inflated membranesget their stiffness and stability.The kinematics and the nearlynon-existent bending stiffness ofmembranes and cables areleading consequently to thetensioned shapes. The shapes aredefined by the equilibrium ofinternal stresses and forces,obeying mechanical principles,and they are not free in theirdesign. Developing tensionedand inflated structures requiresan attitude towards designingstructures that is not justdetermined by the will of thedesigner, but also affected by theprocess of finding the right shapeunder given circumstances, andthe search for the right solutiondefined by the structure itself.The main emphasis of theInternational Students Seminarlies in developing and

manufacturing building modelsfor tensioned and inflatedstructures, including allexperiences during the process ofdevelopment and manufacturing,up to the final and real model.The design of membranestructures is closely related to aninterest in new fields of research,and triggered by some form ofcuriosity while developing, andfun during manufacturing.Interests in new ways of thinkingand unusual approaches areaffecting the appearance of thebuildings.

TARGETThe major aims of the Inter-national Student Seminar are inthe design and manufacturingprocess of tensioned and inflatedstructures. The building processis influenced by an interest ofgetting into new fields, thegathering of experience, and thestepwise success. The design ofmembrane structures is deeplyrelated with the behaviour of thefabric and the possibility totension, join, and fix thematerials. Therefore, one of thetargets of the seminar is to pointout the relation between form,material behaviour, andstructural behaviour which canbe realized during manufacturingand construction. Another aim isto get practical experience indesigning and manufacturingtensioned and inflated

membrane structures. Thepractical experience can hardlybe teached using computermodelling, neither for the 3D-shapes and animations, norfor the numerical simulation ofstructural behaviour. The gapbetween virtual designedstructures and real building isgetting wider and wider, and oneof the aims of the internationalseminar is to show thepossibilities and differencesbetween physical modelling andcomputational design.Participants of the Seminar areteachers of invited EuropeanUniversities, and they arebringing eager students along.These students come fromdifferent fields of study, but theyshare an interest in and anenthusiasm for tensionedstructures. Students have thechance to develop a sense forthese structures by practicalexperience, and have thepossibility to discuss their workwith the participants andprofessionals of the Workshop.Being open minded and free inthinking are the inhibitions ofdesigning tensioned and inflatedstructures, and this will enable anew type of internationalworkshop, combining practicalexperience and theoreticalbackground, while working in thefield of tensioned structures.Main importance is attached tothe interplay between massiveand light structural elements.The light structural elementshave to serve moveability,mobility, sustainability andinnovation, challenging theimagination.

ORGANISATIONThe International StudentsSeminar is part of the TextileRoofs Workshop 2006. Textile Roofs workshops areannually organized by TU Berlin(www.textile-roofs.de) and technet GmbH, Berlin(www.technet-gmbh. com).The participants of the StudentsSeminar have the chance tolisten to the lectures of theworkshop for free. The Inter-national Students Seminar is co-organized by the TechnicalUniversity of Berlin, the Univer-sity of Applied Science Bielefeld/Minden, the University ofApplied Science Munich and theTechnical University of Vienna.Responsible persons for therealisation and organisation ofthe Seminar are P. MichaelSchultes (Vienna) and RosemarieWagner (Munich). P. MichaelSchultes studied architecture atthe TU Vienna and sports at theUniversity of Vienna. He washead of the family companyfrom 1982 to 2000 (www. schulteswien.com).Within the module ExperimentalBuildings at the TU Vienna manyinteresting and non-conventionalproblems have been approached,founding unusual solutions(www.h1arch.tuwien.ac.at/hb1/documents/43/ aufgeblasene_arch_folder.pdf).

Prof. Dr.-Ing. Rosemarie Wagner

R.Wagner@fhm.edu

Prof. Dr.-Ing. Lothar Gründig

gruendig@inge3.bv.tu-berlin.de

Peter Michael Schultes

DESIGN TASK: MOBILE TEA HOUSE“A motorcycle with sidecar stopped in front of the hotel. A manremoved his helmet and started to work. Within a few minutes thesidecar was changed into a small restaurant with two gas cooker anda nice looking table being piled with small tablets full of goodies. Bynow people stopped and picked spits with minced meat, calamaripieces, sausages and chicken wings. They dipped the pieces intoboiling water then into yellow, red or orange dressing, which is addedon small plates, eat while standing and paid afterwards the numberof empty spits they hold in their hand. Everything was clean,appetisingly and was organised at best.The man was Chinese. The poor Malayan had the impression neverbe successful surrounded by such competitor.”from: Tiziano Terzani, A Fortune-Teller Told Me: Earthbound Travelsin the Far East, Three Rivers Press, 2002.

WORK PACKAGEThe project of the seminar is to design and to build on the scale of M 1:5 or M 1:10 a tent which can be stored in the trailer of a bicycletogether with all equipment such as cooker, dishes, silverware, tea,milk, cakes etc.. The tent has to serve space for onetable with 2 guests. The structure ofthe tent can be inflated or tensioned.The best designs will be built in scaleM 1:1 and presented on theconference in Eindhoven, Adaptables ’06, www.adaples2006.nl

INTERNATIONAL STUDENT S SEMINAR ‘DE-LIGHT AND AIR’ TU BERLIN MAI 24 TH – 28 TH 2005

11

A client wantedto build atraditionaltypical ofBahrain old boatout of fabric.The concept wasto make theboat and displayit for theIndependenceDay celebrationin Manama.

The idea sounded dull in thebeginning. But few sketches andquite some moments of thoughtshad formalized the idea of howto do it. Once we knew how totackle the problem, all aspects ofwork came to view so clearly.

The first step was to get theshape of the boat hull to matchthat of the traditional BahrainiBoat. This was done by takendigital photos of boats lying onthe shores of the city ofManama. Ratios representingwidth and heights, andmeasurements of curvatures ofthe boat hull were taken fromthese digital photos. The measurements were redrawnwith AutoCAD. The hull is

6 meter long and the mast is 10 meter high.Once the shape was complete3D Studio MAX was used to givethe boat a more realistic look.The work was presented to thecustomer and we got animmediate approval, as the 3Dpresentation did its magic.From a fabrication point of view,the biggest hurdle in this project

was the forming of the steelmasts to mimic that of thetraditional Bahrain Boat. Weneeded to bend steel, CHS of 8inches with a wall thickness ofabout 15mm, for the support ofthe sail. We needed to get the rightradius of curvature to match thatof the fabric.

That took a lot of ingenuity onbehalf of our fabrication team.

The utilization of the fabric tocreate the boat in its traditionallook was easy. Some detailswere compromised. For example,the hull has got an opening atthe bottom. This is surely notfound in any boat!! However, for us it was necessaryfor the fabrication of the steeland fabric of the hull. Similarlyfor the sail, it was manufacturedas an independent entity. The mast and the hull are doneand manufactured and installedseparately. When all parts wereput together, the picture wascomplete. The design philosophy allowedthe fabrication and theinstallation to be manageable toa very good degree.

3D-model

General view of the Bahrain boat

A traditional typical old boat of Bahrain

Location Manama

Architectural Concept Osama Thawadi

Concept Development Yousif Ahmed

Structural Design Robert Medina

Fabrication and Installation Contractor Gulf Shade - Bahrain

Year of construction 2005

Material PVC polyester fabric: Ferrari 1002, 1050g/m2

FABRICBOAT

www.gulfshade.com • info@gulfshade.com

The TensiNet Association and Techtextil - International Trade Fair forTechnical Textiles and Nonwovens - are holding the 9th Competition onthe subject of: 'Textile Structures for New Building'. TensiNet andTechextil cordially invite students of architecture and civil engineeringto enter this competition. Also invited are all young professionals inthese fields who completed their courses of study after January 1st

2006. The competition aims to promote innovative ideas and problemsolutions in relation to building with textiles or reinforced materials,which have concrete prospects of being realised. The competition alsoaims to promote the prize winning students and young professionals.Furthermore, it is hoped that the competition will intensify contactsbetween the young generation, the universities, the technical textilesindustry and broad areas of the building industry.

Tasks: the subject of “re-usability and recyclability”The competition covers all fields of textile building:• earthworks, traffic-route construction, landscape engineering,

constructions for environmental protection• civil engineering and industrial constructions,• building - from building with textile-reinforced concrete or textile-

reinforced plastics to building with membranes for permanent andtemporary, variable and mobile constructions

• interior fitting - including developments such as the use of polymer optical waveguides for light transmission, textile air-duct systems for draught-free air-conditioning of rooms, mobile sound-insulation walls in production halls, etc.

• product design for architecture.The subject of 'Re-usability and recyclability' has also been included asa main theme. There are no restrictions on the project subject chosen.Both supervised and unsupervised work will be accepted.

PrizesThe prizes will be presented within the framework of a ceremony atTechtextil in Frankfurt in 2007. Additionally, prize-winning projects willbe exhibited in a special show at Techtextil 2007. The organisersreserve the right to exhibit the projects at other Techtextil events and toinform the specialist world and the public about the prize-winningprojects. A certificate will confirm the prizes.

JuryThe members of the 'Textile Structures for New Building' jury willinclude renowned academics and a number of architects and engineerswell known in the field of textile construction. Michael Jänecke, willparticipate on behalf of the organisers.

Composition of the workPlans, photographs or models may be submitted. The work should beorganised in a manner suitable for exhibition max. 2 plans in A0 or 4 plans in A1, max 12 photographs, format min. 18 x 24 cm,1 Model in a solid transport box: surface area max. 70 x 70 cm, 1 A4 page description integrated in the work

Further informationmay be obtained fromMr. Michael Jänecke, from members of theTensiNet Associationor from ILEK, Universität Stuttgart,tel +49 711 685 3599, fax +49 711 685 3789,www.uni-stuttgart.de/ilek

9TH STUDENT COMPETITION 'TEXTILE STRUCTURES FOR NEW BUILDING 2007'

12

Exhibition at Techtextil Frankfurt 2005 ©Techtextil

DescriptionThe project is composed of a pitched roof with a 15° slope thatcovers an 11m (36ft) space with a repetitive 6m (20ft) module. It ismade of hardwood trusses and conic-shaped membranes in PVC, pre-stressed by means of central regulating masts, with lateral scrollableclosures.The membranes are screwed to the structure by means of wood screwswith small aluminium plates.The formal solution resembles the existing wooden construction. Itwas integrated on one of its sides to the main building.

Background InformationLos Teros de Melilla is an estate located on a farm near the city ofMontevideo, dedicated to agriculture and cattle-breeding activities,but whose premises can be engaged for hosting parties and events ofall sorts.

DesignThe roof was generated with a lateral pitch for rain drainage to oneside, beginning at the height of the existing buildings. The roof iscomposed of three 11mx6m (36ftx20ft) independent conical shapes,so as to cover the area with the least amount of structural elements.

Design ProcessOnce the main design parameters were defined, there was specialattention to avoid making the conical shapes too high-rising, and that—at the minimum height— the membrane could perform its functionscorrectly regarding tensions, as well as properly draining rainwater toprevent unwanted ponding.

The membrane was designed with the force-density method, and thecutting patterns defined by triangulating the surface. The wooden elements were designed according to the tensionstransmitted by the membrane, every detail studied in 3D solving alljunctions with the metal fittings, which were specially designed foreach node.

Building ProcessAll the woodwork was prepared atthe carpenter’s workshop, and theironwork at the blacksmith’s.The parts were then set up on site by means of a crane.Next, the membranes were fixed tothe perimeter with plates and woodscrews, and ultimately, the conicalshapes were pre-tensed with thespecially designed regulating masts.

PrestressingThe pre-tensioning of the membranes was done manually by means of three telescopic centralmasts with regulation bolts at their base.

MaterialsThe structure is made of 4x8” Patagonian Walnut (Lapacho), withpainted metal fittings, anchored to the ground through concretebases.

The membranes are made of polyester fabric PES HT 1100dtex, 5x5 threads per cm (12 threads per inch) with PVC coating, UVprotection on the outside, a weight of 800gr/m2 (230oz/sqyd) and abreaking load limit of 30daN/cm (167lbs/inch).

ConclusionsThe objective sought after by the roof was achieved to perfection,accomplishing an enjoyable space for holding events.

MULTI-EVENT AREA “LOS TEROS de Melilla”

Outside views of the Los Teros de Melilla membrane roofs

Connections in the wooden supporting structure

The installation of the membrane

Pre-tensioning the membranes

Supporting construction in woodConical membrane shape

Location Montevideo, URUGUAY

Construction date September 2000

Covered surface 200sqm (2.153sqft)

Roof design and project Roberto Santomauro & arch. Patricia Pinto

Roof structural engineer eng. Marella & Pedoja

Roof fabricator and contractor Sobresaliente ltda

General project arch. Ritorni

Objectives of the Roof1. Eliminating direct solar

radiation that can disturbongoing activities.

2. Allowing entrance of naturallight, at least 7%, so theindoor area is not darkened.

3. Rain protection.4. Low building costs, so as to

keep investment risks low,and not generateconsiderable losses shouldthe enterprise not prosper.

5. Easy installation.6. Special design to provide

distinctive design quality.8. Integrating with the existing

building, without distortingthe existing construction.

tenso@sobresaliente.com, Roberto Santomauro

www.sobresaliente.com

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Reasons for Choosing a Prestressed PVC

Membrane 1. It strictly complies with all

the objectives.2. When compared to other

traditional systems such asglass, plastic, metal orconcrete construction, thesetraditional systems do notmeet all the requirements.Furthermore, some of themadd new problems, such asincreasing internal heat,blocking light completely,and more importantly, notoffering the aesthetic andformal opportunities PVCmembranes have to offer.

1414

A combination of tensioned membranes and a laminated wood structure

Buitink Technology recently finishedthe membrane- and wood structure,which together form the entrance ofthe Dolfinarium in Harderwijk (theNetherlands). Buitink Technologyengineered, produced, and installedthe entrance canopies, as well as themasts with printed flags asdecoration. The architect specificallychose this combination of woodand membranes to create thedesired atmosphere.

It was a challenge to design all the details of the wood structure tobe able to take the large forces resulting from the membranes. Forthis project several specific details were developed.The layout of the bearing structure corresponds to a spine. In thecentre there is a tower, carrying the logo of the Dolfinarium. At bothsides a wooden laminated Larch (spine) beam is placed. It is carriedby portal frames formed by laminated Larch columns and purlins. Inbetween the portal frames purlins are cantilevering from the spine-beam.The architect had designed a rather flat membrane. To prevent largedeformations and ponding of the fabric, the pretension is high. Thetension forces from the fabric, combined with the relatively large

eccentricity, caused by the height andthe curvature of the wooden beams,created large permanent bendingmoments and forces in the wood.This required special detailing of thewood connections. Special attention is paid to the rainflow over the fabric. Because thestructure is an entrance covering, it isnot desirable that the water drainsall along the boundary of the fabric.At the other hand, the architect didnot want to see any water drainagesystem. A compromise was found byadding rims on the fabric, andguiding the water by means of thinchains to the ground. In thepavement drainage systems areprovided.

Buitink Technology buildsentrance of Dolfinarium in Harderwijk

General view

Frontal elevation

Side elevation

Section

Drawing of the wooden structure and membrane

Wooden spine beam and purlins at the entrance

Rather flat curvature of the membrane

Solution to direct the rain flow

The connection of the membrane to the wooden purlin and portal frame

Location Harderwijk, The NetherlandsTotal surface covered: Entrance 205 m2

Lockers 75 m2

Owner Dolfinarium Grévin & Cie, Paris, FranceDesign/Architect Eremco, Paris, FranceMain contractor GMB Infra BV, Opheusden, The NetherlandsWood- and membrane structure Buitink Technology,

DUIVEN, The NetherlandsWood construction GLC Houtconstructies, ARNHEM, The NetherlandsEngineering Wood construction Semplonius Adviesbureau, Laag Soeren

and Adviesbureau Lüning, DoetinchemEngineering membranes Tentech BV, Delft, The NetherlandsMaterial 1002 Fluotop T2 (Ferrari)Year of construction 2005

www.buitink-technology.com

Rienk de Vries , info@buitink-technology.com

Rogier Houtman , rogier@tentech.nl • www.tentech.nl

Exterior view of the glass façade ©Covertex

The connection between the membrane and theglass façade ©Covertex

The membrane cantilevering over the glass façades ©SL-Rasch

15

Furniture and equipment arefrequently difficult to integrateinto the urban or naturallandscape. For monumental sites,historic places, landmarks, andinteresting environments, the“Lleida” prototype was designedin order not to interfere visually.

It is a 6m x 4m self-supportedcanopy, formed by two frames,united by T-shaped cross beams.The beams hold a longitudinalCHS arch that pushes down theroof made of a membrane tiedup to the frames by means ofelastic rope.

The two surfaces includedbetween the frames anddeformed by the arch areanticlastic, resistant to the wind,and they drain properly.

There are no inclined planes,slopes, nor vertical faces thatobstruct the vision, because thesurfaces are perceived as asmoothly deformed horizontal

plane. In this way, the canopydoes not consolidate a volume, as it used to happen to thepitched roofs of pavilions.

The steel sections are lined withrounded pieces of wood toincrease the visual and tactilereceptiveness, thereby raising thetemperature of the metal, andsoftening the aggressiveness ofedges and corners, procuring tothe user the same gentleness thatis provided to the environment.The “Lleida” prototype has beenused in a variety of differentlocations and purposes.

Name of the project The “Lleida” Canopy

Client Lleida City Council

Location Lleida, Spain

Architects Llorens & Soldevila

Membrane structure PVC-Coated polyester

Manufacturing Toldos IASO, Lleida, Spain

Roof area 6m x 4m per module

First year of construction 1987

15

http://www.upc.ed/ca1/cat/recerca/tensilestruc/portada.html

Josep Llorens, ignasi.llorens@upc.edu

UNOBSTRUSIVE CANOPY 2 THE “LLEIDA” PROTOTYPE

The longitudinal courtyard of the Shopping Mall at the KhouraisRoad Retail Centre in Riyadh (approx. 115 m x 10-16 m) is coveredby a Roof Tent Structure. The longitudinal layout of the membraneroof structure is curved in plan and elevation with an axis of symmetryin x- and y direction, and has its maximum width and height at itscentre. The maximum dimensions of the roof in plan are approx. 22 x 130 m with a 3D membrane area of approx. 2 350 m2 and aglazed area of approx. 180 m2. The complete roof structure is generated as a continuous tensionequilibrium form, and this results in the dynamic appearance of theroof structure that is full of suspense.

The membrane roof consists of 15 single segments that aresupported by 14 steel archstructures. The membrane edgesare continuously connected alongthe arched steel frames. Thecurved membrane roof edges thatare cantilevering over the plane ofthe façade are reinforced by steelcables that are spanning betweenthe tips of the steel arches.

The steel arches consist of two curved steel beams with a skylightglazing in between. This skylight glazing is made of ornamented sunprotection glazing. The geometries of the different sized steel framesfollow in height and width the overall curved shape of the membraneroof that is at both short sides connected to the concrete roof slab.The two long sides of the roof tent structure have inclined glassfaçades with an increasing height, approx. 9m towards its centre.These façades are made of an insulated sun protection glazing system.The natural air ventilation and also the emergency smoke exhaust areprovided by automated vents that are integrated with the façade. Theroof itself does not have any openings. There are special cut andspecial sealed glass elements where the curved roof beams penetrate

the façade. The membrane roof and the top of the façade areconnected by a foldable membrane strip to seal the interior air space,and to allow for movement of the membrane under wind.

The rainwater from the tent roof is discharged over the wholeperimeter of the roof, onto the roof deck underneath. There are nospecial rainwater collection points.

All forces resulting from the roof are transmitted to the buildingstructure at the footing points of the steel arch supports, at the twoedge beams, and at the tension bar footing points. The concretestructure of the building is designed to carry all reaction forces from

the tent roof structure. For this,the anchor bolts to connect thetension bars, and the edgebeams are cast with the concreteroof structure. The footings forthe V-shaped steel columns arefixed to the concrete structure byvertical anchors. All horizontalforces are transferred to theconcrete structure by shear pins.

Inside views of the membrane covered Shopping Mall ©SL-Rasch

Client Al Shaya GroupLocation RiyadhArchitects, Structural Engineers (tent roof) Architekturbüro Rasch + BradatschCompletion June 2004Contractor (tent roof) SL- Rasch GmbH with Stahlbau Süssen (steel works)

and Covertex GmbH (membrane works)Dimensions 130m x 22mMembrane Glass/PTFE (2 350 m2)Steel mild steel, galvanized, coatedCables steel cables, galvanizedFaçade insulated sun protection safety glass with ornamented printing

paetzold@sl-rasch.de

www.sl-rasch.de

KHORAISCH ROAD RETAIL CENTER, RIYADHROOF TENT STRUCTURE

Biergarten Details

“The Oyster” Casino del Aljarafe, Sevilla The new Casino will beinaugurated in April 2006. As apart of the rehabilitation works inthe existing office building, a newentrance marquee was planned.The canopy roof was needed toprotect the entrance from therain, as well as from the Sevillasun (more than 3000 sun hoursper year, 19ºC year averagetemperature, 27ºC average inJuly-August). Part of the difficulty of thisdesign was to find a way toanchor the roof to the existingbuilding with an “untouchable”skin of glass and precast concrete

pillars. It was decided to build avery light structure, with specialattention to the transmission ofthe loads to the right points.Therefore, a curved 26m longbeam was fixed to the roof slab,and two masts placed in a V-shape were added in order tostabilize the arch. Smaller mastssupport the high points.Client and building typedetermined the final design. TheV-shape is in fact a reference tothe symbol of victory in casinos. The fabric is a Ferrari 1202 nacre-silver colour, reinforcing theluxury aspect of the roof. Form

and colour provide the roof withits nickname: “The Oyster”.

The fabric is fixed to the arch bya keder and the back borders arepockets with cables tightened tothe three corner plates. Thesecorner plates are connected tothe small masts placed on theroof slab at appropriate points

(heads of pillars, nerves ofslabs), and stabilized by means oftwo cables per mast.These cables are anchored in thelevel +0.60 slab over the roof, inorder to minimize the impact ofthe forces on the curtain wall.The entire structure was planned,designed, manufactured, anderected in 19 working days.

Client: Mace Management - Casino del Aljarafe Proprietor

Engineer: BAT · Buró Arquitectura Textil, Javier Tejera,

José Javier Bataller, Ana Vispe, Rebeca Muñoz, Marian Marco

Manufacture & Installation:Servicios y Constultas, S.L., Antonio Lucena

Fabric material supplier: Ferrari S.A., Joan Nos

General view of the entrance marquee Supporting structure Front view of the entrance marquee

Javier Tejera Parra, tejera@batspain.com • http://www.buroarquitecturatextil.com

Textile roof for a stand at TSV Gersthofen

The textile roof over the standand the terrace has a width of12m and a length of 54m. Four 13m high masts are placed at a distance of 18m in the longitudinaldirection.

The anchorage ofthe cable, running in the longitudinaldirection over the high points of the masts, assures thestability in thelongitudinal direction.

Every 6m, a beam spans in thetransverse direction. The loadsare taken by the connection atthe top and the back side of thestand.

The high points (every 6m) of the membrane are attached to the longitudinal cable. The anti-clastic membrane shape is tensioned between the high points and thetransverse beams of the roof: the snow is carried by the ‘snow bearing direction’, while the upward wind is takenby the ‘tensioning’ direction.The used membrane is PTFE-coated glass.

Client Stadt Gersthofen

Architect Architekten SZZ, Stich, Ziegler, Zirngiebel

Landscaping Eger & Partner, Landschaftsarchitekten

Design & engineering of the tensile roof Kiefer Textile Architecture

Structural engineer Dipl.Ing. H. Steinherr

Material PTFE-coated glass fabric

Year of construction 2005

Michael Kiefer, kpm@amsee.net