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FABRIC ARCHITECTURE•Fabric Architecture offers a complete turn-key solution to tensile structures.

• From initial sketches through to installation, all stages can be planned and executed to budget.

•In-house design, engineering, project management and installation teams provide a wealth of experience and skills. Every detail is considered in the creation of a unique tension fabric structure.

•Tensile structures are becoming much more visible in large public spaces. Soaring panels of lightweight material twisted into fantastic geometric forms above our heads in airports, sports arenas and commercial buildings are now a common sight across the globe. •However, the beauty of these structures and their seamless integration in to existing environments is deceptive. Many of these designs are extremely complex, as are the engineering principles that go into their construction.In the first instance, we need to:• understand the loads exerted by the fabric itself (known as pre-stress or pre-tension)

•Quantify the live loads that the structure will be exposed to (wind and snow) These loads enable us to make some important calculations. We determine the type of fabric required, the size of structural support system required and the foundations that the structure will be anchored to.

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INTRODUCTIONArchitecture is the science and art of designing and constructing buildings. As a science it uses systematic knowledge regarding –(i) materials for construction(ii) techniques of building and(iii) methods of environmental control.

The architecture of any region is the resultant of evolutionary changes brought about during thousands of years.

Today there are many elements of architecture evolved through centuries of science and technology to suit the climate, materials, spiritual values and social norms.

A form of modern architecture may have to be evolved synthesizing these features to provide a cultural continuity to the building art. 

With sustainability as the most important issue in architecture today designers are not only focusing on the use of environment friendly materials but also on their method of construction for reaching ‘green status.’

Since the 1960s, tensile structures have been promoted by designers and engineers such as:- • Ove Arup,• Buro Happold,• Walter Bird of Birdair, •Frei Otto,• Eero Saarinen etc.

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FABRIC STRUCTURE•Are architecturally innovative forms of constructed fibers that provide end users a variety of aesthetic free-form building designs.

• Custom-made fabric structures are engineered and fabricated to meet world wide structural, flame retardant, weather-resistant, and natural force requirements.

•The major benefits were its minimal impact on the environment, its ability to enclose large spaces with little material aid and of their aesthetic quality.

•When it comes to materials and fabric structures, the three basic components to be considered are: the structural members, the membrane and the perimeter tensioning system.

• The structural system is primarily made of steel but aluminium and wood are being considered more often.

•These materials all have many recyclable attributes and can be specified to be manufactured locally to the site.

•Most tensioned fabric structures are designed, engineered and fabricated by “form finding” which means they are designed to be not only structurally efficient but manufactured and installed with little to no waste and energy.

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•Architectural fabric is considered one of the lightest building materials and can create the largest building envelope.

•Properly designed fabric structures may have little impact on the ground with smaller concrete foundations for compression loads and the use of utility cable anchor technology for tension loads. Most fabric structures are composed of actual fabric rather than meshes or films. Typically, the fabric is coated and laminated with synthetic materials for increased strength, durability, and environmental resistance.

•Among the most widely used materials are polyesters laminated or coated with polyvinyl chloride (PVC), and woven fiberglass coated with polytetrafluoroethylene.

•Some commonly used fabrics and their importance:Cotton canvas- The traditional fabric for fabric structures in light cotton twill, light canvas, or heavy proofed canvas. Polyesters -•Strength, durability, cost, and stretch make polyester material the most widely used in fabric structures. Polyesters that are laminated or coated with PVC films are usually the least expensive option for longer-term fabrications

•Laminates generally consist of vinyl films over woven or knitted polyester meshes (called scrims or substrates), while vinyl-coated polyesters usually have a high-count, high-tensile base fabric coated with a bondable substance that provides extra strength.

 

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Vinyl-laminated polyesters•A laminated fabric usually is composed of a reinforcing polyester scrim pressed between two layers of unsupported PVC film.

• With an open-weave or mesh polyester scrim, the exterior vinyl films bond to themselves through the openings in the fabric.

• Heavier fabric scrims, however, are too tightly woven to allow the same bonding. In this case, an adhesive is used to bond the exterior films to the base fabric. A good chemical bond is critical to both prevention of delamination and development of seam strengths.

Vinyl-coated polyester•Vinyl-coated polyester is the most frequently used material for flexible fabric structures. It is made up of a polyester scrim, a bonding or adhesive agent, and exterior PVC coatings.

• The scrim supports the coating (which is initially applied in liquid form) and provides the tensile strength, elongation, tear strength, and dimensional stability of the resulting fabric.

•Vinyl-coated polyester is manufactured in large panels; a proper seam will be able to carry the load requirements for the structure.

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Top coatings -Most fabrics used for fabric structures have some form of top coating applied to the exterior or coating to make cleaning easier. Top coating provides a hard surface on the outside of the material, forming a barrier that aids in preventing dirt from sticking to the material, while allowing the fabric to be cleaned with water. As the material ages, the top coating will eventually erode, exposing the fabric to dirt and making it more difficult to clean. The thicker the top coating, the longer it will last. However, coatings that are too thick will embrittle and crack when folded. There are several commonly used top coatings:

PVF film

PVF lamination is made up of polyvinyl fluoride. It consists of a film layer laminated to the PVC fabric during the manufacturing process. The result is a thicker fabric that can resist weather and chemical agents better than competing fabrics. Its self-cleaning ability repels such things as acid rain, graffiti, and bird droppings. They are often used in industrialized areas ,desert regions, and coastal zones.

 

Acrylic top coatingThis is the most economical and widely available top coating used. Its spray-on application provides a glossy finish and a resistance to UV degradation. Because the coating is thin, the material is both easy to fabricate and is reparable by high frequency or hot air welding. Acrylic topcoats are ideal for fabric structures, and can be found on products used as tradeshow pavilions, temporary concert halls, and portable warehouses.

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PVDF

•These kind of top coating is composed of a mix of fluorine, carbon, and hydrogen.

•The combination of the fluorine and carbon provides superior resistance to UV degradation and chemical damage than that of the acrylic topcoat.

• PVDF coated fabrics also maintain color longer than do those coated with acrylic.

•These coated fabrics are flexible, resist cracking, are easily handled, and generally have a life span of 15 to 20 years depending upon environmental conditions.

•PVDF is chemically grafted to the PVC and polymers used, which reduces the color choices.

 Fabric properties

•When discussing fabric properties for use on a structure, there are several terms that are commonly us.

•Tensile strength.

•It is the basic indicator of relative strength. It is fundamental for architectural fabrics that function primarily in tension.

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Tear Strength –

is important in that if a fabric ruptures in place, it generally will do so by tearing. This can occur when a local stress concentration or local damage results in the failure of one yarn, which thereby increases the stress on remaining yarns. Adhesion strength –

is a measure of the strength of the bond between the base material and coating or film laminate that protects it. It is useful for evaluating the strength of welded joints for connecting strips of fabric into fabricated assembly.

Flame retardancy –

does not have the same meaning as flame proofing.

Fabric that contains aflame-retardant coating can withstand even a very hot point source. However, it can still burn if a large ignition source is present .

Fabric structures Fabric can achieve far greater spans than conventional building materials, with minimal supporting structure.

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•Greater translucency and dynamic, organic shapes bring the feeling of outside inside, as well as providing shade and protection from the weather.

•Tensile structures generate live loads instead of the static loads of traditional roofing materials and modern architectural fabrics offer increased stability and longevity often more than those of other conventional roofing methods. Advantages of using fabric –

• Unique building medium.

• Lightweight and flexible - fabric interacts with and expresses natural forces. •Tensile fabric structures are an environmentally sensitive medium.

•Tension is the most efficient way of using any material, it utilizes the material at maximum efficiency rather than just the material at the extremes of the cross sectional form, as in bending and compression loads. • Fabric structures have higher strength/weight ratio than concrete or steel. • Most fabrics can be recycled.

•A fabric structure can be designed for almost any condition, heavier fabrics and more 3dimensional forms will cope with extreme wind and snow loads.

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Tensioned fabric structures Tensile fabric structures are those in which every part of the fabric is in tension.

The fundamental rule for stability is that, a tensioned fabric structure must curve equally in opposite directions, this gives the canopy its 3-dimensional stability.

This is often referred to as 'double curvature' or an 'anticlastic form' and mathematically it is known as a hyperbolic paraboloid. The complex 3-dimensional form of a canopy is achieved not by elastic fabric, which is stretched into position but by acutting pattern where strips of material with non-parallel sides are sewn or welded together. 

The fabrics cut and bonded together to make its final 3-dimensional shape. Pre-tension is the most efficient way of resisting live loads such as snow, wind etc.

A tensile fabric structure, once it is tensioned, can take a large amount of applied weight and the fabric is extraordinarily tight. If something is thrown onto the fabric, it will bounce off.

These imposed loads or ‘live loads’ are therefore appropriate when the designer wishes to use the minimum amount of material for either functional or aesthetic reasons. Common misconceptions about Fabric Structures 

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It is commonly believed that fabric structures cannot cope in heavy weather conditions  A fabric structure can be designed for almost any condition - heavier fabrics and more 3-dimensional forms will cope with extreme loads, climatic and atmospheric agents.

 It also is commonly believed that fabric is stretchy or elastic in nature  The tensile characteristic nature of fabric structures keep it inert from high winds and heavier loads. They also tend not creep under heavier loads and are a potentially long lasting roofing method.

Supporting framework -Open & Closed Systems An open system has a fabric perimeter supported by an integral cable.

The loads can be substantial on open systems therefore they require larger foundations than a closed system.

Open systems are considered the most sculptural form of tensile structure.

The open system support structure can be edge masts, corner tri-pods masts or central masts with 'push-ups'.

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A closed system structure consists of rigid members around the edge and closed systems require smaller foundations.

In a closed system the fabric edge will be supported continuously by a 'keder' fed into an extruded section, normally fabricated from aluminium. Pros and cons of open and closed system structures. Open system structures tend to move in heavy weather conditions. Trying to join rigid walls

to a free standing open system structure requires a flexible jointing system between roof and wall scan be considered as untidy and unpleasant.

Cost Savings to Fabric Buildings The benefits of fabric buildings are many - No lighting is required as fabric is translucent, which makes it an energy efficient solution.

 Mobility: You can move them, either on wheels or relocate them completely.

Savings: They cost about half of what a traditional structure costs.

It is fundamental for architectural fabrics that function primarily in tension.

Tensile strength is a basic indicator of relative strength.

Tear Strength is important in that if a fabric ruptures in place, it generally will do so by tearing.

This can occur when a local stress concentration or local damage results in the failure of one yarn, which thereby increases the stress on remaining yarns.

Adhesion strength is a measure of the strength of the bond between the base material and coating or film laminate that protects it.

It is useful for evaluating the strength of welded joints for connecting strips of fabric into fabricated assembly.

FABRIC PROPERTIES

When discussing fabric properties for use on a structure, there are several terms that are commonly used:

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To fully understand a fabric's value and usefulness, consider the following:

Shading coefficients

General solar, optical, and thermal performance data

Acoustical data

Dimensional stability

Colorfastness

Clean ability

Seam strength and stability

General handling ability things like : Including abrasion resistance, fold ability, etc.

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TENSIONED FABRIC

STRUCTURES

THE COLUMBUS CENTERInner HarborBaltimore, Maryland

CLOSED TENSIONED FABRIC STRUCTURE

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Tensioned Fabric Structure: A structure where the exterior shell is a fabric material spread over a framework. The fabric is maintained in tension in all directions to provide stability.

DENVER INTERNATIONAL AIRPORT

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PIER SIX PAVILIONBaltimore, Maryland

OPEN STRUCTURE

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CHICAGO’S NAVY PIER

• Unique designs

• Lightweight and flexible

• Environmentally sensitive

• High strength weight ratio

• Little to no rigidity

• Loss of tension is dangerous for stability

• Thermal values limit use

DISADVANTAGESADVANTAGES

• FABRIC STRUCTURES CANNOT TAKE HEAVY WEATHER CONDITIONS FALSE

• FABRIC IS ELASTIC AND STRETCHES Fabric has a strong tensile strength and will creep (stretch very slightly) only a few percent over 20 years of use.

COMMON MISCONCEPTIONS

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TYPES OF FABRIC STRUCTURES

• Saddle roof• Mast supported• Arch supported• Point supported• Combinations

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SADDLE ROOF

• Four or more point system when the fabric is stretched between a set of alternating high and low points

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MAST SUPPORTED

• Tent - like structures containing one or more peaks supported by poles (masts) or a compression ring that connects the fabric to the central support.

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ARCH SUPPORTED

• Curved compression members are used as the main supporting elements and cross arches are used for lateral stability.

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ALUMINUM FRAME SUPPORT

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COMBINATIONS

• Combination of several support types.

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COMPONENTS

BASE PLATE

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• Connection to concrete foundation pillar

• MAST SUPPORTED

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BALE RING / MEMBRANE PLATE• Provide a link between the membrane and structural elements..

– Bale rings are used at the top of conical shapes. – Membrane plates accept centenary cables and pin connection

hardware.

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MEMBRANE

Forms the enclosure of the structure. Connections can be glued or heat welded.

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MEMBRANES

• PVC coated polyester (polyvinylchloride)

• Silicon coated glass

• Teflon coated glass P.T.F.E (polytetra fluroethylene)

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• PVC • Less expensive• 15 to 20 year life span• Easy to erect

• SILICON GLASS

• Higher tensile strength• Brittle, subject to damage from flexing• 30+ year life span

• TEFLON GLASS

• Similar to silicon glass, less brittle.

TYPES OF FABRIC MEMBRANES

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SPECIALIZED HARDWARE

Tensioner

Extruded section with membrane plate and centenary cables

Tripod head with centenary cables

Centenary cables at a side connection

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SPECIALIZED HARDWARE

CABLE CLAMPS

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WATER DRAINAGE VIA MEMBRANE PLATESOPEN STRUCTURE

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WATER DRAINAGECLOSED STRUCTURE

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SOLAR BEHAVIOR

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ENVIRONMENTAL IMPACT

• Longer life cycles of materials.

• Materials can be re-used in form.

• Most materials are completely recyclable.

• Less impact on site.

• Less construction debris after demolition.

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Fabric Architecture:Material Choices

• Indentify and compare a variety of architectural fabrics for designing fabric structures

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Materials For Fabric StructuresIt’s all about the coating…

• It seals the fabric against weather• provides resistance to ultraviolet light• functions as a medium for joining panels• fire-rated (Class A,B,C, NFPA 701)

Today’s Materials come… different widths

variety of colors

some can accept graphics

different light transmission

vary in life span

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Other issues include… Selecting the proper Fabric

Size Form Span Function Availability Economics Sustainability

Today’s fabrics include:

Teflon coated fiberglass (PTFE) Ethylene tetrafluoroethylene (ETFE) Vinyl coated polyester (PVC/PVDF) High density polyethylene (HDPE) Laminated Products Theatrical Draperies and Stretch Fabrics

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Make Mine Non Combustible…Teflon Coated Fiberglass (PTFE)

large scale permanent structures

Non Combustible (Class A)

life span of over 25 years

off white color during installation

Colors now available

membrane bleaches to milky white

2009 Pricing: $75-125 /sqft.

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Other “Non-combustibles”…

•Silicon Coated Fiberglass

•Hybrid PTFE (Gore brand Tenara)

•TiO2 (Titanium Dioxide) Photocatalyst membrane

• 2009 Pricing: $85-150 /sqft.

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Ethylene Tetra fluoroethylene (ETFE)

high transparency (97%)

more than 25 year life span

self cleaning

single or multi-layers

100% recyclable

2009 Pricing: $100-150 /sq.ft.

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Make mine PVC

Vinyl Coated Polyester (PVC/PVDF)

most cost effective

temporary and permanent structures

soft, pliable and easy to handle

less expensive than PTFE and ETFE

variety of colors, weights, topcoats and textures

Fire resistant (Class C, NFPA 701)

life span of 20+ years

2009 Pricing: $50-75 /sq.ft

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What’s not to like…

•Perforations, translucency•Stretches nicely•Different seam width•A variety of manufacturers•10-15 year warranties• Recyclable

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Made for the Shade High Density Polyethylene (HDPE)

shading only (UV stable) variety of styles, colors & shade factors high tensile strength Fire and non fire resistant well suited for dry/hot climates protection from sun and hail 2009 Pricing: $25-50 /sq.ft

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Mesh is hot so you can stay cool……

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If you want to keep it simple… Acrylics, Coated and Laminates

Tent and Awning Industry

variety of styles, colors & patterns

low tensile strength

Fire and non fire resistant

Exterior Shading Devices

2009 Pricing: $35- 50 /sq.ft

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A little bit of this, a little bit of that…

• Textile Facades• Graphics• Textures• Digital Printing• Truly unique patterns

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Keep it inside… Theatrical Drapery and Stretch Fabrics

Interior Applications and Lighting Fixture variety of styles, colors & patterns and cost! low tensile strength Fire resistant Self supporting, tensioned or draped No snow load! 2009 Pricing: $30-100 /sq.ft.

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Soft Spaces…• Hides mechanical systems• Acoustical helper• Light reflector• Transforms spaces

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Photo Voltaic and Custom Fabrics

Thin film PV

Sustainability

multi-purpose structures

custom colors, textures, patterns

Form follows Fabric, Fabric follows form

2009 pricing: Unknown

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Anatomy of a Fabric Structure (% varies)Plan Area (Length x Width) X Shape Factor (H) = Surface AreaSurface Area X Cost per SQFT= Budget

Design (DD to CD)

Engineering (awning to dome Stadium)

Project Management (scope of work)

Steel Fabrication (large variable)

Membrane Fabrication (based on complexity)

Installation (location, location, location)

Shipping (dedicated truck, gas prices)

Teflon coated fiberglass (PTFE): $75-125Other “non-combustibles”: $85-150Ethylene Tetra fluoroethylene film (ETFE): $100-150Vinyl coated polyester (PVC/PVDF): $50-75High density polyethylene (HDPE): $25-50Laminates and Interior Fabrics: $35-50Future “Fabrics” unknown

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Are you ready for a quiz?

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Question 1

• Which material is best used for permanent structures requiring a Class A rating or is “non combustible”?

A. Teflon Coated Fiberglass (PTFE)B. Vinyl Coated Polyester (PVC)C. High Density Polyethylene (HDPE)

Question 1:Answer: A, Teflon Coated Fiberglass. PTFE is a Class A non-combustible material used for permanent applications.

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Question 2

• The best material for applying graphics to is:

A. Teflon Coated Fiberglass (PTFE)B. Vinyl Coated Polyester (PVC)C. High Density Polyethylene (HDPE)

Question 2Answer: B, Vinyl coated polyester. PVC is the most common material used for background to vinyl applied digital printing and screen printing ink.

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Question 3

• A. True or B. False• Architectural Fabrics vary in color,

weight, light transmission and cost.

Question 3Answer: True. Yes, Architectural Fabrics vary in color, weight, light transmission and cost.

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Question 4

• The overall cost of a fabric structure is most effected by:

A. The fabric chosen.B. The amount of steel required.C. The material finishes.D. The size of the project.E. All of the above.

Question 4Answer: E. All of the above. The chosen fabric, the amount of steel and the finish specified for the steel, fabric and cables effect the overall cost. The size can play a major role too. As the larger the structures becomes, the lower the overall cost becomes on a square footage basis.

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Contact Information

• www.fabricarchitect.com• www.fabritecstructures.com

• Samuel J, Armijos, AIA• 89 Glenroy Road East

• Fairfield, NJ 07004• 973.244.5871

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LINKS……………….• BIRDAIR, INC. -

– www.birdair.com• SPRUNG INSTANT STRUCTURES LTD.

– www.sprung.com• FABRIC ARCHITECTURE

– www.fabricarchitecture.co.uk• FABRITEC STRUCTURES

– www.shadeconcepts.com

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