Architects: Davis - Brody; deHarak, Chermayeff & Geismar (designers)
Roof Structural Engineers: Geiger - Berger Associates
The U.S. Pavilion at Expo 70 in Osaka is one of the very few embodiments
of major technical and architectural innovation that was also
built quickly and inexpensively. Trying to best R. Buckminister
Fuller's Geodesic Dome built for the U.S. Pavilion at Expo 67
in Montreal (figure 1), the architects of the Expo 70 Pavilion
first envisioned it as a huge floating sphere, inspired by NASA's
Apollo 11 mission that put the first man on the moon (figure 2).
This spherical scheme was the winning entry (submitted by Davis
- Brody Architects and deHarak, Chermayeff & Geismar, Designers)
in a competition sponsored by its future owner, the United States
Information Agency (USIA). The competition
scheme would have included exhibition space inside the sphere,
and used its inner surface as a giant projection screen for continuously
played film clips. The Pavilion ultimately erected at Osaka marked
the birth of a new structural building type -- the longspan, cable
stiffened pneumatic dome -- which would for a time become the
predominant roof system over America's emerging sports palaces
(figure 3). Remarkably, the U.S. Pavilion's pneumatically supported
465 foot by 265 foot clear span dome was developed largely in
response to Congress' 50% reduction in the project's budget. The
completed Pavilion cost $450,000, which was about half the cost
of the Montreal dome.
Despite its extraordinarily economical $4.5 per square foot cost,
the U.S. Pavilion was a masterwork of structural elegance and
recent technological advances. The interior of the Pavilion was
inflated like a balloon, putting its entire roof in tension, and
allowing it to be made of fabric and cables.
The completed roof's 1.5 pound per square foot weight was only one
fifth that of the Houston Astrodome's, built in 1965. The Pavilion's
primary structure and enclosure systems were made from only four
materials: vinyl-coated fiberglass fabric and steel cables for
the roof, held in place by a reinforced concrete ring girder resting
on an earth berm (figure 4). The roof's fiberglass was initially
developed by NASA as an extremely fire-resistant material after
the death of three astronauts on a launching pad in 1967. It would
have been impossible for engineers to predict the roof's aerodynamic
but flexible behavior in Osaka's typhoon winds without the help
of recent advances in computers and numerical analysis techniques.
The earth berm supporting the roof was built of soil excavated
from the site to make room for the lower levels of the Pavilion,
and was simply bulldozed back into place when the building was
disassembled.
The
elegant simplicity of the U.S. pavilion's architectural detailing
both harmonized with and emphasized its new structural form. Exhibition
platforms were laid out to follow the diamond pattern of the roof
cables above. The fiberglass fabric roof was translucent, allowing
diffused sunlight to provide most interior lighting during the
day; at night interior electric lights made the roof glow softly
when viewed from outside. Interior finishes and exhibitions celebrated
advanced and emerging technologies. The earth berm was covered
with then-exotic foil-faced Mylar; the USIA used artifacts like
the Apollo 11 space capsule to extol NASA's achievements. These
features expressed a utopian view of technology that the Pavilion's
architects and engineer embraced when describing future applications
of pneumatically supported domes. Soon after the completion of
the U.S. Pavilion, engineer David Geiger claimed that "there
appears to be no maximum span for application of this type of
roof," and architects Davis-Brody published plans for enclosing
an entire town underneath similar structures.
Sources:
Conniff, Richard. "After a while, nothing seems strange in a stadium with a 'lid'." Smithsonian (January 1988): 114-125.
Cowan, Henry J. "The Pre-History of Lightweight Structures." Lightweight Structures in Architecture 1. The First International Conference on Lightweight Structures in Architecture, 1986: 50-8.
Fuller, R. Buckminster. Inventions:The Patented Works of R. Buckminster Fuller. New York:St. Martins Press, 1983.
Geiger, David. "U.S. Pavilon at Expo 70 Features Air-Supported Cable Roof." Civil Engineering-ASCE (March 1970).
Shaeffer, R.E. "History and Development of Fabric Structures." Abel et al. Spatial, Lattice and Tension Structures. ASCE Structures Congress XII, IASS International Symposium, 1994: 979-89.
Tenfo, Alva. "Environmental Control--U.S. Pavilon." Building Research (January-February 1972).
Villecco, Marguerite. "The Infinitely Expandable Future of Air Structures." Architectural Forum (September 1970).
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