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1Prof. G G Schierle, PhD, FAIA
Design of Fabric StructuresSession T33, Thursday, 04/30, 2 3:30
PM
Design of Fabric Structures
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2Acknowledgements/Credits
This presentation includes book excerpts of
Structure and Design
http://www.universityreaders.com/titles/schierle/
Design of Fabric Structures
This program is registered with the AIA/CES for continuing
professional education. As such, it does not include content that
may be deemed or construed to constitute approval, sponsorship or
endorsement by the AIA of any method, product, service, enterprise
or organization. The statements expressed by speakers, panelists,
and other participants reflect their own views and do not
necessarily reflect the views or positions of The American
Institute of Architects or ofAIA components, or those of their
respective officers, directors, members, employees, or other
organizations, groups or individuals associated with them.
Questions related to specific products and services may be
addressed at the conclusion of this presentation.
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3Learning Objectives
Evaluate appropriate uses of fabric structures, i.e., select
appropriate fabric structure types, and select and specify proper
fabric material
Design efficient fabric structures, design fabric structure
details, and select and design proper fabric boundaries
Evaluate the cost of fabric structures, day-lighting of fabric
structures, and the appropriateness of fabric structures for
various loads
Design of Fabric Structures
Saddle shape Wave shape Arch shape Pont shape
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4Anticlastic Stability
Two stressed strings stabilize a point in space
Two sets of strings form a stable surface
Without prestress, convex fiber gets slack, causing
instability
Flat fiber deforms greatly under load, causing instability
Triangular panels are flat & unstable (AVOID)
Prestress Prestress (PS) effect on a stringF = force, P = load,
= deflection 1 Without prestress top link resists all
Assume: = 12 With prestress = 1/2
Top link increase: F=PS+P/2Lower link decrease: F=PSP/2
3 Stress / strain diagram f/A without prestressB with prestressC
Prestress reduced to PS = 0D Prestressed string after PS = 0
Cable nets need about 50% prestressFabric structures need about
30%
prestresshttp://www-classes.usc.edu/architecture/structures/papers/GGS-Yin.pdf
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5Minimal SurfaceCriteria: Minimum surface area Equal stress
throughout Equal +- curvature at any point
Governing Equations (Schierle 1977*)*First published 1977
inJournal of Optimization Theory and Applications
F1/F2 = A/B
Y = F1(X/S1)K/F1+ X tan Y = F2(Z/S2)K/F2
K= F1+F2
Sm
all d
efle
ctio
n
P
rinci
pal c
urva
ture
Larg
e de
flect
ion
Stra
ight
gen
erat
ing
line
Fiber orientationGood Flawed
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6Fabric Properties
8 to 20 kN/m46 to 114 lb/in
Permanent + mobileInternal + external
Flouro-polymer fabric
Coated or uncoated fabric*
40 to 100 kN/m228 to 571 lb/in
Permanent + mobileInternal + external
PTFE fabric(good qualities for sustainability)
Coated or uncoated fabric*
6 to 12 kN/m34 to 69 lb/in
PermanentInternal + external
Flouro-polymer foilETFE
Foil*
6 to 40 kN/m34 to 228 lb/in
Permanent internalTemporary external
PVC foilFoil
50 to 100 kN/m286 to 571 lb/in
Permanent Internal + external
Fine mesh fabricLaminated with PTFE film
Laminated fabric*
20 to 100 kN/m114 to 571 lb/in
PermanentInternal + external
Glass fiber fabricSilicone coating
Coated fabric
20 to 160 kN/m114 to 914 lb/in
PermanentInternal + external
Glass fiber fabric PTFE coating
Coated fabric*
40 to 200 kN/m228 to 1142 lb/in
Permanent + mobile Internal + external
Polyester fabric PVC coating
Coated fabric*
Tensile strengthCommon useMakeupType
* Self-cleaning
> 25 yearsUp to 90 %++++
> 25 years15 to 40 %++++
> 25 yearsUp to 96 %++++
15 to 20 yearsinternally
Up to 90 %+0
> 25 years35 to 55 %++++
> 20 years10 to 20 %++++
> 25 years4 to 22 %++++
15 to 20 years0 to 25 %++
DurabilityTranslucencyUV light resistance++ very good+ good
Fire rating++ incombustible+ low flammability0 none
Maximum spansAssuming: Live load LL = 20 psfSafety factor Sf =
4Span/sag ratio L/f = 10
Fabric breaking strength Max. span600 pli (lb/in) ~ 60 ft800 pli
(lb/in) ~ 80 ft
200 pli800 pli150 pli600 pli100 pli400 pli
Design stressTensile strengthDesign stress (tensile strength /
4)
Costs Type Cost / sq. ftPrefab PVC $15 to $20Custom PVC $30 to
$60PTFE Teflon-coated fiberglass $60 to $180Note: costs exclude
foundations
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7RL
RR
H
H
TR
TL
W= w L
w
h
RL
RR
L/2L
f
f H
Symmetric suspensionHorizontal reaction H = w L2/(8f)Vertical
reaction R = w L/2Max fabric tension T = 1.35 w L
Asymmetric suspensionVector methodTotal load W = w LFabric
tensions TR TLHorizontal reaction HVertical reactions RL RR
w
Design / AnalysisRadial loadEdge cable tension T = R p
Lateral LoadSeismic (not critical)V = Cs WV = seismic base
shearCs = Seismic coefficient W = mass (dead load)Example (V / ft2,
Cs = 0.2, w = 1 psf)V = 0.2 x1 V = 0.2 psf
LDG: Lateral Design Graph Sample: 100 x 50 x 20
Wind (critical)Velocity 90 mph (most USA) 150 mph (Golf
coast)Gust factors (G= 0.85 for rigid structures)G ~ 1.5 for fabric
structuresExample (V per ft2, p = 20 psf ~ 90 mph)V = p G = 20 x
1.5 V = 30 psf
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8Acoustics Thin fabric provides little sound insulation
Micro-perforated foils absorb sound(suspended under structural
fabric)
Form may be used to control acoustics Anticlastic forms disperse
sound Synclastic forms focus sound
LightingDaylight sunny days ~75000 luxDaylight overcast ~25000
lux10% translucent fabric ~2500 - 7500 luxTypical office lighting
~1000 lux
ThermalWhile fabric has low R-valuesThermal reflection is very
good
Surf
ace
cond
ition
sP
oint
sha
pe A
rch
shap
e
Wav
e sh
ape
Sad
dle
shap
e
Edge
con
ditio
nsE
dge
beam
Edg
e ar
ch
Edg
e ca
ble
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9Edge Conditions
Edge Cable (tension)
Edge Arch (compression)
Edge Beam (bending)
UCB Canopy
Stage canopy
Edge
Cab
le
tens
ion
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10
Raleigh Arena North Carolina (1953)Architect: Novicki and
DeitrickEngineer: Severud Elstad Krueger
Edge arch / cable roof
EFL portable classroom (1968)Architect: G G SchierleEngineer:
Nick Forell
Edge arch / anticlastic Fabric
Sony Center BerlinArchitect: Helmut JahnEngineer: Ove Arup
Edge ring / radial cables and fabric
Edge
Arc
h / R
ing
co
mpr
essi
on
Horticultural CenterGallaway Gardens, GeorgiaBy ODC
Dining Pavilion Saddlebrook FloridaBy Helios Industries
Note:Edge beams facilitate assemblies
Edge
Bea
m
bend
ing
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11
Saddle shapes Wave shapes
Surf
ace
cond
ition
s
Arch shapes
Stay
ed
Mas
ts
D
ish
Rin
g
P
unct
ure
Pro
pped
Mas
ts
E
ye
Loo
p
R
adia
l Point shapes
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12
Saddle shapes
Courtesy USA Shade
Expo 64 LausanneArchitect: Saugey / SchierleEngineer: Froidevaux
et Weber
26 restaurant pavilions: Featured Swiss regional cuisines
Symbolizing sailing and mountains
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13
R=100
L=120
f=12
A A
B
BSection B-B
Design example
Assume:
Wind pressure p = 30 psf
Allowable fabric stress Fa= 200 pli
Available canvass stress Fa= 50 pli
Wind load (normal to fabric)
T = p R = (30)(100) T = 3000 #
Fabric stress per inch
f = 3000/12 f = 250 pli
Fabric NOT OK 250 > 200 > 50
Cable net was required
Assume: Same allowable stressGravity load w = 20 psfGraphic
method
Total LoadW = w L = 20 (120) W = 2400 #Horizontal reaction H =
3000 #Vertical reaction RL= 2400 #Fabric tension T = 3720 #Fabric
stress (#/in)f = 3720#/12 f = 310 pliGravity load not OK
310>200>50Cable net was required
L=120
f=12
A A
B
B
h=40
HRL
f RL=2400#
H=3000#
W= 2400#T=3720#
w = 20 psf
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15
Wave shapes
Computer model
San Diego Convention CenterArchitect: Arthur EricksonEngineer:
Horst BergerFabric design: Horst Berger
Concrete pylons at 60 supportridge, valley, and guy cables
thatspan 300 between pylons
Translucent Teflon coated fiber glass fabric provides
daylight
Ridge cables support gravity loadValley cables support wind
upliftGuy cables support : Flying buttresses
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1Denver AirportArchitect: FentressPhoto: David Benbennick
Denver AirportPhoto: David Benbennick
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17
Sony Center BerlinArchitect: Helmut JahnEngineer: Ove Arup
Truss compression ring 335
Flying buttress mast supports
top tension ring
Radial guy cables support mast
Radial roof cables hold fabric
Translucent fabric
Arch shapes
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18
Study model
EFL portable classroom (1968)Architect: G G SchierleEngineer:
Nick ForellSize: 30x40First twin fabric with thermal insulation
Theater pavilion Armonk (1968)Architect: G G SchierleEngineer:
Nick ForellSize 60x80 - capacity 600Longest span fabric roof 1968
fabric tensile strength 720 pli
Skating Rink MunichArchitect: AckermannEngineer: Schlaich /
BergermannPrismatic arch truss supports translucent PVC fabric on
wood slats and cable net
Arch truss detail
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19
Point ShapesSt
ayed
M
asts
Dis
h
R
ing
Punc
ture
Pro
pped
M
asts
Eye
L
oop
Rad
ial
Hudson River Park PavilionNew York, NYCourtesy USA Shade
Sea-World Pavilion VallejoArchitect: G G SchierleEngineer: ASI,
Advanced Structures Inc
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20
Fabr
ic p
atte
rn s
eam
Twin
fabr
ic @
hig
h st
ress
Pre
stre
ss tu
rnbu
ckle
Web
bing
hol
ds fa
bric
Fabric corner Ground anchor
Twin fabric @ high stress
Mast topDet
ails
Erection
Color lighting
Layout
Erection
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21
German Pavilion Expo 67 MontrealArchitect: Gutbrod &
OttoEngineer: Leonhardt & Andrae
Translucent fabric for naturallighting suspended from cablenet
on 3-D adjustable hangers.Prefab panels assembled onsite with
lacing.
Balance Forces
Unbalanced
Balanced
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22
Stretch fabric design / testing model
Design ProcessStretch Fabric models
Stretch fabric models for form-finding and testing
Design ProcessComputer Aided Form-finding Analysis Pattern
design
Computer modelComputer model
Load shape dotted lines
CAD patterns by triangulation
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OptimizationEdge & surface curvature(Schierle, 1971)
Usual optimum L/f = 10L = spanf = sag L
f
Watts Towers Cultural Center (2002)Architect: Ado /
SchierleEngineer: ASI
Removable fabric and cable truss
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Stadium Oldenburg GermanyArchitect: Kulla, Herr und Partner
Engineer: Schlaich Bergermann
Anticlastic fabric panels suspended from cantilever cable
trusses
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25
Grid Shell Mainz, GermanyArchitect: Mutschler / Otto Engineer:
Ove ArupGrid shell of 50 cm square, 50 mmtwin slats form rhomboids
in space; covered with translucent fabric.
Form-finding model
Millennium Dome LondonArchitect: Richard RogersEngineer: Buro
Happold
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anticlasticfabric
Cur
ved
wal
l to
resi
st w
ind
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27
Speaker
Prof G G Schierle, PhD, FAIAUSC - School of ArchitectureLos
Angeles, CA 90089-0291
T 213-740-4590F
[email protected]://www.usc.edu/structures
Prof G G Schierle, PhD, FAIAUSC - School of ArchitectureLos
Angeles, CA 90089-0291
T 213-740-4590F
[email protected]://www.usc.edu/structures
http://www.universityreaders.com/titles/schierle/
thank youthank you