Photos courtesy of Cary Kopczynski & Co. The Escala was the first building in North America to use 100 kilopounds per-square-inch steel for seismic reinforcing.

The goal with Escala, a 30-story luxury condominium tower in downtown Seattle, was to create large, open spaces unimpeded by walls and columns.

Cary Kopczynski & Co. developed a dual system for seismic resistance that incorporates minimal shear walls at the stairs, supplemented with ductile moment-resisting space frames. This nonconventional dual system worked well with the architectural layout without compromising the open and spacious unit plans.

The seismic system required an exceptionally high concrete strength of 14,000 pounds per square inch at the lower levels of the building. Working with the city of Seattle, CKC got approval to use reinforcing bar with a yield strength of 100 kilopounds per square inch, in lieu of traditional 60-ksi bar.

A 40 percent reduction in steel requirements at the Escala condominium tower in Seattle reduced rebar tonnage, congestion and field labor.

Escala became the first building in North America, and perhaps the world, to use 100-ksi steel for seismic reinforcing. The 40 percent reduction in steel requirements reduced rebar tonnage, congestion and field labor, allowed use of traditional vibrators for concrete placement, and helped accelerate the construction schedule.