| History
of Tensile Structures: |
| For 4,000 thousand years tensile principles have been
used in bridge building as the only way to span large distances.
Throughout the Far East and South America, suspension bridges
made of rope and bamboo were used. Although bamboo is quite
strong, it is not very durable. A more lasting solution
came in 100 AD, when the Chinese invented wrought iron.
Some of the early bamboo bridges could span over 800 feet.
It was not until the introduction of steel cable in the
nineteenth century that western engineering could greatly
increase that span.
Despite all these precedents, tensile architecture never
really took off until after WWII. Frei Otto was the seminal
figure in the development of tensile architecture. He
was the first to lead away from the simple geometric solutions
to the organic free forms that could respond to complex
planning and structural requirements.
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Tensile
Structures:
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A special feature of Tensile membranes is
that their form is completely integrated with their structure:
the shape of the building is determined by the physical
characteristics that maintain its strength, and that strength
is achieved almost exclusively with tension forces. They
are therefore almost unique in the range of construction
materials, which usually rely on compression or bending
forces. In other words, a tensile structures is a building
that is made from materials under tension.
The main requirements of tensile fabrics
are strength, non - combustibility, long life, low heat
absorption, resistance to dirt and easy cleaning, and
ease of handling.
Fabrics can be used to make building envelopes
that are much ligther than those formed by conventional
means. And they have therefore primarily been used in
situations where portability or speed of erection has
been a requirement - mobile dwellings, military shelters
and circus and other entertaiment venues being most common. |
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History of Pneumatic Structures:
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The Chinese developed the first hot air balloons
from paper. In the eighteenth century, lightweight, close weave
cotton fabric made the first passenger hot air balloons possible,
and this led to the giant gas-filled airships and zeppelins
of the early twentieth century. The development of synthetic
fibers such as nylon and improved coating techniques led to
innovative balloon designs, and the appearance of the first
pneumatic buildings during the Second World War.
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The system is based on the creation of air pressure between
the ground and the membrane. Using air as the suppoting element
of the membrane skin to bear compression loads, a great range
of efficient structures can be developed that can cover extremely
wide spans. They are also sometimes called inflatables.
Pneumatic structures are mostly used for roofing very large
areas, such as athletic facilities, greenhouses, temporary exhibitions.
Pneumatic or inflatable structures are basically of two types:
1)Air-supported structures; 2) Air-inflated structures
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