Cable and tensile structures

Cable and tensile structures

1. CABLE & TENSILE STRUCTURES
Rohan Joshi -Assignment 3

2. Cable structures
Cablesaremadeofaseriesofsmallstrands
twistedorboundtogethertoformamuch
largercable.Steelcablesareeitherspiral
strand,wherecircularrodsaretwisted
togetherand"glued"usingapolymer,or
lockedcoilstrand,whereindividual
interlockingsteelstrandsformthecable.
Cableisaflexiblestructuralcomponentthat
offersnoresistancewhencompressedor
bentinacurvedshape.Technicallywecan
saycablehaszerobendingrigidity.Acableis
themaincomponentofcablesupported
bridgeorsuspendedroofstructures.
Classificationofcablestructures
Suspensiontypecablestructures:
Thebasicstructuralcomponentsofa
suspensionbridgesystemincludestiffening
girders/trusses,themainsuspensioncables,
maintowers,andtheanchoragesforthe
cablesateachendofthebridge....Themain
loadcarryingmemberisthemaincables,
whicharetensionmembersmadeofhigh-
strengthsteel.
Cable-stayedtypestructures:
Acable-stayedbridgeisastructuralsystem
withacontinuousgirdersupportedby
inclinedstaycablesfromthetowers.Form
themechanicalpointofview,thecable-
stayedbridgeisacontinuousgirderbridge
supportedbyelasticsupports.

3. Tensilestructures
Atensilestructureisaconstructionofelementscarryingonlytensionandnocompressionor
bending.Thetermtensileshouldnotbeconfusedwithtensegrity,whichisastructuralformwith
bothtensionandcompressionelements.Tensilestructuresarethemostcommontypeofthin-
shellstructures.
Tensioned Fabric Structure :
Astructurewheretheexteriorshellisa
fabricmaterialspreadoveraframework.
Thefabricismaintainedintensioninall
directionstoprovidestability.
Tensile Structures :
Tensionroofsorcanopiesarethoseinwhich
everypartofthestructureisloadedonlyin
tension,withnorequirementtoresist
compressionorbendingforces.

4. Advantages of tensile Structures
FlexibleDesignAesthetics-Tensilemembranestructuresprovidevirtuallyunlimited
designsofdistinctiveelegantformsthatcanberealizedbecauseoftheuniqueflexible
characteristicsofmembraneresultinginaniconicanduniquestructureorfeatureforany
buildingowner,cityorevenregion.
OutstandingTranslucency–Indaylight,fabricmembranetranslucencyofferssoftdiffused
naturallylitspacesreducingtheinteriorlightingcostswhileatnight,artificiallighting
createsanambientexteriorluminescence.ExcellentDurability–Withseveraldifferent
membranesinthemarketplacesuchasPTFEfiberglass,ETFEfilm,PVC,andePTFE,the
durabilityandlongevityoftensilemembranestructureshavebeenproven.
LightweightNature-Thelightweightnatureofmembraneisacosteffectivesolutionthat
requireslessstructuralsteeltosupporttheroofcomparedtoconventionalbuilding
materials,enablinglongspansofcolumn-freespace.
LowMaintenance–Tensilemembranesystemsaresomewhatuniqueinthattheyrequire
minimalmaintenancewhencomparedtoanequivalent-sizedconventionalbuilding.
CostBenefits–Mosttensilemembranestructureshavehighsunreflectivityandlow
absorptionofsunlight,thusresultinginlessenergyusedwithinabuildingandultimately
reducingelectricalenergycosts.

5. Atwo-dimensionaltensionfabricmembranecantakeplanartensileforces,butitcannottake
significantforcesperpendiculartothisplane.Therefore,inadditiontobeingpre-stressed,
tensionfabricmusttakeacertainthree-dimensionalshape,inordertoremainstable.These
shapeswerediscoveredbyOttoandBergerduringtheirinvestigationofnaturalforms,such
assoapbubbles.Therearetwotypesofgeneralshapes:
Types of Tensile structures
AnticlasticShapes:
AnticlasticShapesarecreatedbyhavingthe
radiioftheprincipalcurvaturesonopposite
sidesofthetensionfabricsurface.Asaresult,
whenloadedataparticularpoint,tensionwill
increaseononecurveofthemembraneand
leavetheoppositecurve.Thereby,preserving
equilibriumandkeepingthestructurestable.In
ordertokeepanticlasticshapes,somekindof
structuralframeorsupportisnecessaryinthe
formofcablesorsteelbeams.Someexamples
ofanticlasticshapesaresaddle,coneandwave
forms.
SynclasticShapes:
SynclasticShapesarecharacterizedbyhaving
theradiioftheprincipalcurvaturesonthesame
sideofthefabric.Inordertocounteractexternal
forces,pressurefromthewithinisnecessary.
Thisiswhysynclasticshapesareassociatedwith
air-inflatedstructures.Thedifferenceof
pressurecreatedbyairpumpedintothe
buildingisabletocounteracttheexternal
forces,intheformofwindorsnow.

6. Whetherit’sapermanentdurablestructurethatneedstolastlongerthan30years,an
insulatedmembranesystemforthermalperformanceoradeployableflexibleapplication,
thereareavarietyoftensilemembranestochoosefromtomeetspecificperformancesfor
yournextbuildingproject.
ByusingtranslucenttensilefabricmembraneslikePTFE,PVC,InsulatedTensileMembraneor
transparentETFEfilms,daylightismaximizedinbuildinginteriors,thusreducingthecostsfor
electriclighting.
ThefollowingaretypesoftensilemembraneswhicharewidelyusedinIndia–
•PVC(Poly-vinylChloride)
•FRP(FiberglassReinforcedPlastic)
•PTFE(Polytetrafluoroethylene)
•FILM
Types of Tensile Membranes

7. PVC(Poly-vinylChloride)
PVCcoatedpolyestercanbeagreatmaterialchoiceforbothpermanentandtemporarytensile
fabricstructures.PVCcoatedpolyesterisknownforitsexcellentstrength,flexibility,translucency
andaffordabilitycomparedtoFRPandPTFE.ThePVCcoating,whichisappliedtopolyester
includesUVstabilizers,fireretardantadditives,andanti-fungicides.PVCcoatedpolyesterfabrics
haveastructurallifespangreaterthan20years.
PTFE(Polytetrafluoroethylene)
PTFEcoatedglassclothwasdevelopedbyDuPontinthe1960sandhasbeenusedtocreate
tensilefabricstructuressincetheearly1970s.Originally,thematerialhadalifespanof25years;
however,thishasalreadybeenexceeded,withpresentdayexpectationslyingsomewhere
between30and50years.Today,itisconsideredtobethehighestqualitymaterialforcreating
tensilefabricmembranesandthebestchoiceifyoudesirealonglifespanandlowmaintenance.

8. FRP(FiberglassReinforcedPlastic)
FRP(FiberReinforcedPolymers)materialisatypeofcompositematerialthatisincreasingly
usedintheconstructionindustryinrecentyears.Duetotheirlightweight,hightensilestrength,
andcorrosionresistanceandeasytoimplementationmakesthesematerialpreferredsolutions
forstrengtheningmethodofreinforcedconcretestructuralelements.Inthisstudyitisaimedto
discussadvantagesofFRPusageasacompositematerial.Itisnotedthatthemechanical
propertiesofthesematerialsshowsausefulbehaviorforstrengthenedtheoreticallytosatisfy
safecross-sectionwithFRPmaterials.
NAME FEATURES BUILT TYPE SPAN MARKET RATE
PVC Easily assembled
Eco friendly
Prefab 20-30m 300/sq.ft
PTFE Superior quality
Water proof
easy installation
Panel Build
Modular
25-45m 1750/sq.ft
FRP Light weight
High tensile strength
Corrosion resistance
Prefab 40-60m 75/sq.ft
Film Waterproof
Easily available
Post-
stressed
25-45m 350/sq.ft
The following table constitutes the properties of different tensile membranes in the Indian market

9. References
•https://www.rstensile.in/tensile-structure-manufacturer-in-india.html
•https://www.rstensile.in/tensile-fabric.html#tensile-fabric
•https://architizer.com/blog/product-guides/product-guide/tensile-fabrics/
•https://www.slideshare.net/MimiAlguidano/cable-and-tensile-structures-for-architecture-
and-engineering