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Recent innovations in materials and technology are leading designers to create air-supported fabric structures with higher-level capabilities than ever before.
By Bruce N. Wright
Air-supported fabric structures have been around since at least the mid 1940s, when Walter Bird developed for government use the archetypal fabric-clad radome to protect sensitive radar equipment from the elements. Along with inventing a new technology, Bird helped invent airtight rubberized fabric with high-performance characteristics, thus ushering in a new construction category, the structural fabrics industry that continues today. Some of Bird’s first postwar non-military applications were for protective bubbles over swimming pools. The business he created to make pool enclosures, Birdair, continues today as a leader in tension structure design and manufacture.
Over time, two approaches to the design of air-supported structures have evolved-from an engineering/architecture perspective and from a product design point of view-and both are nicely embodied by two very successful companies with roots in the UK: Tectoniks Ltd., of Shropshire, England, and Inflate, located in London.
Tube city
Tectoniks was started in 2006 as an offshoot of Lindstrand Technologies, the manufacturer of high-performance, high-altitude hot air balloons. Led by David Kelsall, technical director and co-founder, Tectoniks has focused exclusively on designing and manufacturing fabric structures that incorporate a number of innovative air-support technologies. Their approach is to begin with the engineering and apply known structural concepts and fabrication details worked out over many years of designing for tension structures. Tectoniks’ methodology uses pressurized fabric air tubes that are combined into curved arching forms, the accretion of tubular layers providing the structural strength and stability. There is a consistent appearance to all of Tectoniks’ work; three recent examples are cases in point. This winter, Tectoniks’ design of the Coca-Cola pavilion at the 2014 Winter Olympics in Sochi, Russia, wowed the attendees with its dynamic forms and intense red color. A series of fabric tubes welded to form a double dome shape are connected seamlessly together to suggest half of a Coke bottle lying horizontally. Entrances, circular air-filled fabric rings, are placed at the two widest bulges of the bottle shape, and the assembly lit up at night with red light. The pavilion is actually the most visible vestige of a four-year initiative by Coca-Cola to promote healthy lifestyles in Russia. After the Olympics venue, the mobile pavilion began traveling to many communities across the country, expounding the message of movement as happiness.
Equally interesting is Tectoniks’ Dreamforce 2013 event structure that overtook an entire block of San Francisco for almost a week in late November. The 100m-long (330 ft) by 18m-wide (60 ft) structure appeared in front of the Moscone Conference Center in the city as the main venue for a four-day business/entertainment trade show.
Perhaps the most technically advanced structure in Tectoniks’ portfolio is its transportable custom structure for Lockheed Martin UK, a controlled environment for sensitive equipment that is designed to travel on rails, as well as dismantle and pack into shipping containers to move long distances as needed. Measuring 14m (46 ft) by 14m by 20m (66 ft) high, the structure is mounted on a wheeled aluminum truss system that allows it to move up to 50m (164 ft) distance. Comprised of inflatable walls and an inflatable rolling door that also forms the roof, the structure deflates and packs into six 20 ft shipping containers for easy transport.
Architecture as product design
Inflate-known for its variety of air-supported structures most often used in promotions or events-began as an idea by Nicholas Crosbie while he was a student at the Royal College of Art, London, studying industrial design. “I first had the idea of making something out of air-inflated plastic sheeting in 1993 while I was a student, when I came upon a machine in the RCA’s model shop that could weld synthetic fabrics and plastics,” Crosbie says. “I made an inflatable bag, a portfolio to put my design work into for protection and transport. It got a lot of positive response and led me to continue experimenting with the machine and materials.” This tinkering with machine and materials eventually led in 1995 to a company that produces unique products using cellular inflated shapes that can be made into almost anything. “My philosophy has always been to experiment with the material and the process,” Crosbie says. “To just enjoy the machine’s capabilities with the material at hand, and not have preconceived expectations on the outcome. One day the effort produces an inflatable wine rack, the next an inflatable fruit bowl.” One of the first commercial products to come out of this technique of “hacking” the process was a structure for indoor use called “Office In a Bucket,” an inflatable dome that could be used to set up a conference space or temporary office within an open space in more traditional office buildings.
Inflate’s designs are seldom the same, unless it’s one of their prefabricated structures for rental use or purchase. Its newest product line, called “Airclad,” has a modular frame wrapped in a double layer inflated fabric skin, and can extended to any length by adding modules. With a patented technique for sealed fabric cells, Airclad structures begins with a square or rectangular ring frame that supports the floor, walls and ceiling and is bolted together ring-to-ring for any length as needed to create column-free interior space. The ends of this tube-like form can be enclosed with a glass wall and door assembly or a solid wall closure. The system works well and is quickly put in place on almost any surface, urban hardscape or green field alike. A six-module, 139m2 (1,500 sq ft) Airclad was used as the security accreditation check-in office for the 2012 London Olympics placed outside St. James Palace for what became the Great British Creative embassy during the Olympic and the Paralympics Games.
Inflate also has developed a wide variety of structures for exterior use and has grown to include creative design offices in Antwerp (where its “Airclad” line is produced) and Berlin, in addition to London.
Inspired by new materials
As every designer worth their salt knows, seeking out new materials can often lead to new designs or new interpretations of older designs. The same can be said for fabric structures. About 20 years ago, ETFE foil hit the market as a new building material. Adapted from its original use as an insulator for electronics and aeronautical applications*, transparent ETFE was applied by designers as a clear version of fabrics for shading structures or as roofs over swimming pools and spas. First attempts to use the membrane were limited to single layers.
Architects and engineers quickly learned that the material acted very much like fabric in its anticlastic (double curvature) behavior and that tensioning it provided stability. This meant that traditional tension structure hardware and rigging methods were ideal. Experimentation soon led to placing two and three layers of ETFE together and inflating the assemblies like pillows to increase insulation values. The added advantage is the membrane is strongest when in tension by pressurization. Recent innovations include the addition of sophisticated frit patterns printed on the ETFE membrane to control light translucency.
A recent project that takes this concept to new lengths is the central bus station canopy in Aarau, Switzerland, considered the largest installation of ETFE in the world. Designed by Zurich architects Mateja Vehovar and Stefan Jauslin, with technical and structural design and engineering by formTL of Radolfzell, Germany, the canopy is in the shape of an undulating cloud with a trilobal opening in the middle. The ETFE pillow form is hemmed in on both inner and outer edges by a tapered steel rim, the whole assembly supported by a few slender steel columns scattered here and there and anchored in concrete islands that form queuing lines for the buses. The upper surface ETFE is tinted a sky blue, the lower surface left transparent. Both surfaces are held in place by randomly skewed suspension cables crisscrossing between the inner and outer steel edge curves. In addition, the blue tint contains a bubble pattern printed into the tint surface.
As these examples show, the possibilities for air-supported fabric structures are limitless and whatever form they take will depend upon the creative imagination of designers who seek an alternative to more traditional building technologies.