Erector Tops Out 850-Foot-Tall Rainier Square Tower in Only 10 Months

Rainier Square Tower is the proof of concept for a revolutionary type of steel frame with a modular shear wall core made of dual cross-tied steel plates, field-filled with concrete.

Photo by Brian Morgen/MKA

As predicted, the Erection Co. topped out Seattle’s 850-ft-tall Rainier Square Tower, with its radical composite steel frame dubbed “speed core,” in only 10 months. Steel erection began last October in the lowest basement.

The retail-office-residential building is on course for substantial completion next Aug. 13, according to Andy Bench, project manager for the developer, Wright Runstad & Co.

The core, surrounded by a conventional steel frame, consists of a modular sandwich system of cross-tied steel-plate walls, field-filled with concrete. The modules were fabricated by the Supreme Group. The system requires no rebar and no formwork. The steel erector installed the final core module on Aug. 9.

The overarching aim is to usher in an era of speedier, safer and better office tower construction, compared with concrete core towers with steel perimeter frames. Ron Klemencic, chairman and CEO of the project’s structural engineer, Magnusson Klemencic Associates, and the mastermind behind the scheme, reports MKA has five other speed-core buildings on the boards in three projects in California.

Nadine M. Post, ENR's former editor-at-large for buildings, is an award-winning journalist with 45 years of experience covering trends, issues, innovations, controversies and challenging projects. Post has written about many industry giants, including 10 ENR Award of Excellence winners. And she has covered disasters, failures and attacks, including the 1993 bombing and the 2001 destruction of the World Trade Center. Project stories include the redevelopment of the World Trade Center; the 828-meter-tall Burj Khalifa; Los Angeles’ Disney Concert Hall; and Seattle's Bullitt Center and Rainier Square Tower. In 1985, Post wrote McGraw-Hill's book Restoring the Statue of Liberty (1986) for the restoration’s architects—Richard S. Hayden and Thierry W. Despont.

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