The Rainier Square Tower (59-story, 850 ft/ 259 m tall) in downtown Seattle, is getting off the ground, with its completion scheduled for early 2020.
Traditionally, a rebar-reinforced concrete core has been the preferred method of construction for Seattle’s towers. These cores are very good at bracing against wind and seismic loads. The construction process is slow, though: three to four days per floor, with the steel framing for each floor dependent on completion of the concrete work.
For Rainier Square Tower, a new steel plate & concrete composite fill design for its high-rise core is used. It has been developed by Magnusson Klemencic Associates (MKA) over many years. The system uses two steel plates connected by steel spacing ties, and then the cavity between the plates is filled with high-strength concrete. An added boon is that this method is expected to reduce traditional construction time by 30% or more.