Up, Up and Away
Inflated flexible membrane forms with innovative construction techniques are creating a new forming option in thin shell concrete structures. This concept is being used successfully in homes, public buildings, and storage facilities. This article discusses the design and use of balloons for forming concrete structures.
Air-Supported Forming: Will it Work?
An overview of air-supported formwork for constructing concrete shells, some prudent suggestions, and a prognosis for the future are given.
Inflate it First
Low-cost concrete shells have been built by spreading dry cement mortar at ground level between layers of nonwoven reinforcing fabric that is anchored at the shell perimeter. This is then inflated with a blower to form a dome and sprayed with a hose to harden the cement. Construction shortcuts, material costs, and maintenance and repair are described.
The Binishell system--Thin Shell Concrete Domes
The Binishell system of constructing thin shell concrete structures by using air supported forming is described. The development of this patented system, its uses, and applications for grain storage structures in the Middle East are outlined.
Suitable Shell Shapes
The use of air-supported forming as a method for controlling forming costs for concrete shells is under study at the Institut fur Massivbau of Stuttgart University in Germany. The possible shapes for shells have gone past conventional geometries and experimental and mathematical methods are being used to design shell shapes. Studies of the technical feasibility of these shapes include the control of formwork deformations and their effects on the setting concrete.
The Shape of Things to Come
An architect with a patented method for building an air-supported concrete shell describes the evaluation of his system and the construction of his own home.
Controlling Construction Mishaps
Concrete domes in excess of 200 ft (61 m) in diameter have been built successfully using air forms. The domes have many uses ranging from houses to large auditoriums and commercial buildings. Storage of granular materials has proven very practical with some storing as much as 40,000 tons (36,290 Mg) of fertilizer or 1 million bushels of wheat. The use has extended to the storage of liquid materials. Water tanks have become practical and economical. Construction problems have included collapse of the air form, collapse of the concrete and steel, uplift of the footing, and excessive stretch of the forms. The problems have been overcome and expanded use of the air form continues. Domes up to 300 ft (91 m) in diameter are currently being considered.
Esthetic, Social and Environmental Aspects of Concrete Shells Constructed on Air-Supported Forms
The construction of concrete shells on air-supported formings will allow man to erect humane, ecologically sound, efficient structures on locations inaccessible to or impractical for previous builders. This method not only opens up previously closed avenues of construction, it is also easily adapted to modern technology which can make the process nearly hazard-free and flawless. With proper understanding of the complex processes involved, engineers and designers will be able to execute successful applications of a method which promises to usher in a new era of architecture.
A Dome in the Mountains
An air-formed concrete shell home in the Colorado Rockies incorporates the architectural and engineering advantages of this construction method.