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Structuring the River Stalks

Cesar Pelli & Associates worked with structural engineers Tomoki Hashimoto and Mitsubishi Heavy Industries. They decided early on that key pieces of the vertical structure that plunge to the lower level would actually tie into members that are part of the orthogonal structural grid. The 100-year flood level is slightly above the skylight, so the challenges were above grade as well as below.

In order to resist extraordinary hydrostatic pressure resulting from the underwater site — as well as for economic reasons — the building was constructed in a top-down fashion: The highest below-grade floor was built first, followed by the middle and finally the lowest, descending 74 feet (22.5 meters) into the subsurface of mud and water. This process allowed the earth that remained in place to resist the pressure of river water on the exterior walls as the museum was constructed.

The surrounding 10-foot- (three-meter-) thick wall is composed of three layers. The outermost is a thick vault of concrete; in the middle is another concrete layer with a rubberized waterproofing membrane designed to control temperature and humidity and act as a secondary water stop; and the third and innermost layer is the finished wall of the museum.

Fabricating the Ribs

The oversized stainless steel members were constructed in factories near Tokyo typically dedicated to fabricating machine parts for industry. Entire rooms of the factory were devoted to producing the curved stainless steel reeds.

The members, measuring up to 203 feet (62 meters) each for a total of 8,530 feet (2,600 meters) in length and 212 tons (192 metric tons) in weight, were then disassembled and shipped to Osaka in long sections and mounted and welded in place.

After assembly, the wrapping was removed and — to allow the metal to shed water and be self-cleaning — the entire structure was coated with a thin protective film of liquid titanium. The cool luster of the titanium coating creates an extraordinary visual relationship between it and the blue of the sky.

Glazing the Sculpture

At street level, a thin glass membrane enclosing the lobby nestles within the stainless steel sculpture, carefully integrated into and around the vertical members. A sliding plate connection allows the stainless steel to penetrate the glass so that the steel structure can move without disrupting the glazing.

Within the lobby, the filtered light and shadow of sunlight settling through the stainless steel elements creates an extraordinary diffused, shadowy effect. Daylight penetrates below the ground through skylights, light wells, and courtyards to reach all three levels of the museum.

During construction, the effect of this glass bubble was observed in all types of weather conditions. Perhaps the most beautiful was during heavy rainstorms, when water streams across the gently curved surface of the glass roof and one feels as if one is diving beneath a moving river into a thicket of cool, silver reeds.

Despite the structure's deceptively machine-made appearance, much of it was built by hand, woven as one would weave a basket. Japan is the perfect place to create such a highly crafted building, given the Japanese construction industry's talent for precision. On the typical construction job, several members of the design team are at the site at all times, along with representatives from each of the various consulting firms.

Although Japanese buildings are very well detailed in construction documents, much of the technical design happens on site; shop drawings are done in conjunction with site work. A large number of workers collaborated on the Osaka site to realize this building.

The excitement and magic of the light, space, and structure could already be felt a year and a half before opening. Construction lasted five years, the majority of which were spent below ground. Now the ambitious and seemingly contradictory dream to create a highly visible underground landmark in Osaka has become a reality.   >>>

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Raul A. Barreneche has worked at Architecture magazine as executive editor and is the author of numerous books on architectre and is contributing editor to Metropolitan Home, Architectural Record, and Travel + Leisure.

This article is excerpted from Sections Through a Practice: Cesar Pelli & Associates, copyright © 2003, available from Hatje Cantz Publishers and at Amazon.com.

Construction of the National Museum of Contemporary Art, Osaka, Japan, by architect Cesar Pelli & Associates and structural engineers Tomoki Hashimoto and Mitsubishi Heavy Industries. Photo: Jun Mitsui & Associates All the pieces were custom-formed, though made from standard pipe sections. No two were alike, and they could only be of a limited length for ease in shipping. Photo: Jun Mitsui & Associates Before shipping, the ribs were preassembled to make sure all the connections were right, and the curvature was verified with computer data. Then the sections were disassembled, wrapped in a protective high-tech shrink-wrap, and shipped to the site in Osaka. Photo: Jun Mitsui & Associates The largest cluster of vertical tubes being assembled at the site. The base plate is still visible from the pavilion entry. Photo: Jun Mitsui & Associates The base plate without the protective wrapping displays a hairline-finish stainless steel with a soft, reflective gloss. Photo: Jun Mitsui & Associates Before any of the main structure was put in place, the exterior trusses for the skylight were installed with the mullion system suspended below. Photo: Jun Mitsui & Associates In a typically immaculate Japanese construction site, scaffolding surrounds the main cluster of structural tubes as they rise from a lower level. Photo: Jun Mitsui & Associates The connection where the double-truss meets the concrete curb only needed to be a certain thickness so it was slimmed down as much as possible. The pin connection allows the structure to rotate slightly. Photo: Jun Mitsui & Associates   Click on thumbnail images to view full-size pictures.