The Mark is a 750,000 SF, 48-story commercial office and hotel tower that’s reshaping the Seattle skyline, and designed to preserve the historic Jacobean-style Rainier Club and the nation’s oldest Byzantine-style church next door. Utilizing a compact footprint at ground level, the tower subtly slopes over the site’s existing structures before tapering back through a precise system of steel “knuckles” and triangulated building planes.
Preserving and incorporating the First United Methodist Church into the new development, the tower rises from the city block with a faceted form. At the tower’s base, a transparent entrance lobby and lower level facade integrates with The Sanctuary and The Rainier Club to provide an enclosed court between buildings. With 15,000 square feet available on The Mark’s first floor, the floorplates needed to expand on subsequent levels to maximize leasing potential. Through a joint development agreement with The Rainier Club, ‘over-under’ property rights are utilized. It is Seattle’s first tower with column-free floors and floor-to-ceiling windows—more per square foot than in any other building in the city.
At the heart of the tower is a diagonal steel mega-brace system. The exposed braces zigzag up the tower’s facade and are embedded 11 inches into its reflective glazing. The intersections of the braces are called “the knuckles,” where brace members were initially bolted and finished with penetration welds. The knuckles are a result of the desire to stitch the building together along its corners, even though the design also mandated that the same corners be column-free. Every knuckle had to occur at a floor level, so that forces from braces on two orthogonal faces could be resolved into the floor structure.
The structural system shifts the load away from the core and to the exterior walls, allowing for a smaller core and creating more rentable floor space. ZGF and Arup worked with steel fabricator Supreme Steel to create the knuckles with a Halfen anchoring system for the building’s unitized panels. Supreme Steel developed a detailed three-dimensional model showing all of the welds and plates. The mega-brace structural technology enveloping The Mark is a first for towers in high-seismic regions.
The design optimizes building height, configuration and floor plate efficiency while responding to the owner’s vision for an iconic addition to downtown Seattle’s skyline. Allyn Stellmacher, a partner at ZGF Architects, talked about what it meant to rethink tall buildings in the city. “Our client, Kevin Daniels, envisioned a project that could reset expectations for high-rises in Seattle. Alongside our project partners, it was gratifying to help make our mark on the skyline.”
ZGF associate Henry Zimmerman and Arup associate Bryce Tanner will be presenting The Mark on the panel”Thinking Outside the Box: Detailing and Fabrication Considerations for Advanced Building Geometries,” at The Architect’s Newspaper’s upcoming Facades+ Seattle conference on December 6.