1200 Stewart St

Two 48-story residential towers over 5 below-grade parking levels

Seattle

1200 Stewart St

Northwest

Ceco Concrete is providing full concrete frame services—including all formwork, concrete supply, shotcrete and pump, place and finishing work—for two 48-story residential towers over five below-grade parking levels in the heart of Seattle’s Denny Triangle Urban Center Village. The project also includes an 8-story podium structure that will house a state-of-the-art concert venue that the structure was modified to include after construction had started.

The project’s structural design consists of a central three-celled core wall, perimeter columns and flat mild-reinforced slabs in both towers. The unique floorplate features undulating balconies that rotate and wave as the structure climbs up. Ceco employed self-climbing core wall formwork and Ceco’s truss table fly forms to achieve this demanding design.

Work began May 2019. After pushing through the base structures, the towers advanced amazingly fast, despite several hurdles, including:

  • The Ceco team had to execute a 1,550-cubic-yard deck pour with 590 tons of rebar on a challenging transition level. The vertical elements transition into two tower configurations via deep, heavily reinforced transfer beams. Level 1 required 5,800 cubic yards of concrete and 1,500 tons of reinforcing in total.
  • The dramatic overhangs of the balconies also created a significant challenge. The Ceco team collaborated with the client and the City of Seattle to coordinate work so that it took place during off-peak hours and scheduled street closures. This enabled our team to fly out the massive form tables supporting the balconies over public streets, keeping everyone safe and with minimal interruption to the surrounding community.
  • The project stalled for a brief time under Washington State’s COVID-19 stay-home mandates during March and April 2020.

Once restrictions for commercial construction were lifted in May, the Ceco team once again tackled this exciting project. In all, Ceco is providing 92,000 cubic yards of concrete and we are on schedule to complete the final roof pours in December 2021.

Drone video (top) and aerial photography courtesy Tim Rice.

 

Project Details

  • Project Owner:
    Westbank
  • Contractor:
    Graham Construction
  • Architect:
    Henriquez Partners Architectsv
  • Structural Engineer:
    Glotman Simpson
  • Gross Building Area:
    1,600,000 sf
  • CECO Scope:
    Full Concrete Frame Services
  • Date Completed:
    2021