Construction of the 850-foot-tall, $570 million-to-$600 million Rainier Square Tower in Seattle is turning out to be a proving ground for innovation.
According to Construction Dive, “Aluminum components are being 3D printed with the resulting v-shaped nodes and connected squares of curtain wall forming a dramatic slope from the fourth to 40th floors. Aside from the impressive aesthetic, this method of production can also more easily accommodate last-minute changes.”
The article goes on to explain, “Structural engineer Magnusson Klemencic Associates (MKA) started out planning to use a reinforced concrete core for the building, said firm CEO Ron Klemencic, and about halfway into the project, it was clear that the tower would be too expensive and was going to take too long to build, making it economically unfeasible for the building’s owner, developer Wright Runstad & Co.” So after tabling the project for over a year, they needed an idea that would “jumpstart the project without busting the budget.”
MKA’s mission, in 2006 and 2007, to convert steel-plate composite-core technology that was being used in the defense and nuclear industries into a design that would work with high-rise construction. What resulted is a concrete-filled composite steel plate shear wall (CF-CPSW) core that starts with prefabricated panels made up of two structural steel plates held in place with cross-connecting tie rods. The tie rods, according to the American Institute of Steel Construction (AISC), support each panel before the concrete is poured during the erection process. The tie rods also place pressure on the concrete, which increases seismic performance.
Using this system, the AISC estimates that erection crews will be able to top out about 43% faster than if they had to build a traditional core. At the Rainier Tower Square project, using SpeedCore allowed crews to top out in 10 months, which was about half the time allotted in the original schedule, said Lawrence Kruth, AISC vice president of engineering and research.
In addition to the potential for a shorter timeline, the SpeedCore system offers other benefits as well:
- Strength. The concrete-filled prefabricated steel panels make for a robust structure, which is not surprising since the U.S. Department of Defense, Klemencic said, valued its blast protection qualities and the nuclear industry its resistance to projectiles.
- More flexibility for adaptive reuse. The SpeedCore system has no hidden rebar, making the structure more predictable during adaptive reuse projects.
- Safety. Because the progression of work on the system is so close to that of floor framing, much of the tasks take place under steel decking, meaning workers are protected from falling objects.
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