National Museum of the American Indian

Sited prominently between the National Air & Space Museum and the U.S. Capitol, the Smithsonian’s National Museum of the American Indian on the National Mall is a centerpiece venue for ceremonies and presentations, as well as a primary exhibition space for Indian arts, histories and cultures.

The 260,000-square-foot, five-story structure reflects the relationship between humankind and the rest of nature, with references to the four cardinal directions and the four elements of the world – earth, air, water and fire. The five-story curvilinear building is clad in Kasota limestone that evokes natural rock formations of the southwestern United States. The building’s special features – an entrance facing east toward the rising sun, a prism window and a 120-foot high entrance called the Potomac – were carefully designed in close consultation with the Native American community over a four-year period to reflect beliefs and meanings in Native American culture.

The structure contains six footprints, undulating perimeter walls, real boulders and constructed water features and a 45-meter entrance overhang reminiscent of age-old cliff dwellings. No two floors have the same geometric layout, and the design contains many compound curves and changing radii throughout the building. There are more than 500 work points, each of which represent the center of a circle and can generate multiple radii. Within the building, there are easily over 1,000 curves and little repetition. In addition, the structure features a roof that cantilevers above the entrance at the eastern end.

To undertake the challenge of constructing such a complex facility, Clark employed several different concrete forming systems including European formwork systems made by Conesco Doka. Because the foundation walls are curved with no repetitive radii, the Conesco Doka adjustable radius formwork system was used for its flexibility. The adjustable system is capable of forming concave or convex walls with radii as tight as ten feet. In addition, eight separate custom-made shear wall forms were used to form the curved vertical shafts that house mechanical risers and stairways within the structure. The form systems used on the project ultimately increased productivity and helped control quality by rigidly maintaining the varying concave or convex radii for the different geometric configurations once the forms were set into place.

The museum is designed to resist seismic and wind loads, primarily by transferring loads to the shear walls of the stair and elevator cores placed throughout the building. Over 1,000 friction-resistant driven piles of epoxy-coated steel support the structure.