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September 28, 2018

Architectural and artistic (nonresidential)

Photo provided by WACA
Inside the Spheres is a five-story independent structure made with 12 million pounds of concrete.

The Spheres

Location: Seattle

Owner/developer: Amazon.com

Team: Sellen Construction, general and concrete contractor; NBBJ, architect; MKA, structural engineer; Stoneway Concrete, ready-mix supplier

The Spheres are a product of innovative thinking between the owner and design team through an extended conversation about what’s typically missing from urban offices: a direct link to nature.

The Spheres are a place where Amazon employees can work and interact in an environment more akin to a garden than an office — an alternative workplace that fosters collaboration and innovation.

The facility is intended to delight, both inside and out. For the uninitiated visitor, it is an unexpected surprise in the cityscape. Views of its interior garden and accessible exterior landscape benefit the entire community, but particularly surrounding neighbors. For employees, it is the stimulus for serendipitous connections and a shared place where they are invited to think and work differently.

Separate structures support the exterior envelope and the five interior floor levels. This separation allows the self-supporting external shell to be as light and transparent as desired. The design team sought a unique structural system for the enclosure that would be modular and repetitive so that it could be largely fabricated off-site, but also highly organic in appearance to reflect the interior use.

The selected pattern was derived from a “Catalan” solid known as a pentagonal hexecontahedron. Essentially, a single pentagon of set dimensions is arrayed 60 times to form a complete sphere.

The enclosure structure and glazing system continues uninterrupted to street level so that the three spheres appear to be partially buried.

The project is both an experiment and a legacy project. The Spheres has an iconic structure recalling a traditional domed conservatory but is the product of design and engineering innovation.

Less visible from the outside is a five-story, independent concrete structure inside the Spheres made with 12 million pounds of concrete reinforced by 2.5 million pounds of rebar. Undulating concrete floor edges swim past the Catalan structure or pull away to create dramatic spaces. Two concrete shear cores resist seismic loads.

While the typical concrete shear core is rectangular-shaped and rough construction, these concrete cores were shaped like a football and a guitar pick with an exposed finished surface. The design team also wanted the structure to be a sculptural feature. The curved forms were over-sized by 2 inches, and form-liner pieces were used to impress a tree pattern climbing up the core.

Concrete also became the material to form the planter beds in the conservatory areas. These planters curve, swoop and dive to create spaces for introspection, conversation or exploration.

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