[RED_PDXer]

I came across this article and was amazed at how quick this tower went up.

The thought of constructing a tower core without rebar would cause many builders to scoff.

But the project team behind a 58-story tower under construction in Seattle is working to prove that there may be a better, faster way to build tall.

Seattle-based engineering firm Magnusson Klemencic Associates (MKA) has pioneered a new type of high-rise building core that utilizes a concrete-filled composite plate shear wall system called SpeedCore. The system was used for the first time on Rainier Square, an 850-foot-tall mixed-use tower being built by general contractor Lease Crutcher Lewis.

The building was designed by NBBJ for Seattle-based developer Wright Runstad & Company.

Because the concept was utilized for the first time on such a high-profile project, there are a lot of eyes on the work being done....

The SpeedCore concept was actually borrowed from methodology used around the world to construct nuclear power stations, Morgen said.

“The loading is entirely different with blast and projectile,” he said. “You have thick walls for out-of-plane loading, while for tall buildings we’re using the same concept in a completely different manner. Extrapolating it to Rainier Square was the first real world application when it comes to high rises.”

So how does it work?

Because concrete in a building core is normally poured days or even weeks before structural steel is erected on the same level, the leading core method leads to completion of the building core long before the rest of the building catches up.

By contrast, erection of a SpeedCore structure begins with prefabricated panels consisting of two structural steel plates held in place with cross-connecting tie rods. After erection, the panels are filled with concrete, which is poured from the bottom of the panel. The resulting sandwich provides strength and stability along with significant on-site time savings.

It does away with the need for curing time entirely by eliminating the need for a leading core. Also, it eliminates the need for formwork, installation of rebar, embedded plates, sleeves and block-outs.

“In SpeedCore you could do two floors in one week,” Morgen said. “Now, what you’re doing is trading prefab time offsite to achieve that; that does have lead time associated with it.”

And now the involved firms know the concept works as intended.

The Rainier Square project topped out after just 10 months, achieving a construction rate of roughly 1.35 floors per week. The system has shorted the timeline of the project, which is slated for completion in March 2020, from 40 months to 31 months.

Full article (behind pay wall)