Tower Gets Go-Ahead for New Core Design
A new core system design for Seattle’s under-construction Rainier Square Tower has been approved, giving the innovation the green light from a design standpoint.
Engineering News-Record reports that a three-person peer-review panel gave the go-ahead for the 850-foot “proof of concept tower,” which is slated to use a composite structural steel frame instead of the traditional steel frame around a reinforced concrete core.
The Structure
The design for the $370 million project is aiming to change the game for seismic and wind resistance for tall towers. (Rainier is slated to be the Pacific Northwest’s second tallest.)
“This is going to be a watershed in terms of high-rise construction,” said Shannon Testa, senior project manager for general contractor Lease Crutcher Lewis.
The 58-story tower’s construction is slated to take 40 percent less time than a traditional design. Those in charge of erecting the steel superstructure—set to begin in August—say that job will take about one year (around nine months less than normal).
The key to this, reports ENR, is the composite steel frame with a shear-wall core, which has a system of cross-tied steel-plate walls filled with concrete.
This application is the first of its kind for a building of this height aiming for an earthquake-resistant core and was developed by structural engineer Ron Klemencic, chairman and CEO of Magnusson Klemencic Associates.
“Rainier Square brings together my insatiable search for ‘better,’ passion for research and development and intense collaboration with the entire design and construction team to create a breakthrough in how tall buildings are constructed,” Klemencic told ENR.
Michel Bruneau, a professor of engineering at the State University of New York at Buffalo and a co-investigator for ongoing physical load tests at Purdue University, peer-reviewed the structure and praised the design.
“On the basis of what we’ve seen, this is an excellent application [of the module], and it will be pioneering in its use in further high-rise construction,” Bruneau said, calling the system “so clever, I don’t understand why it hasn’t been done before.”
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The 58-story tower’s construction is slated to take 40 percent less time than a traditional design. Those in charge of erecting the steel superstructure—set to begin in August—say that job will take about one year (around nine months less than normal). |
When studies surrounding the Coupled Composite Steel Plate Shear Walls system are complete, the American Institute of Steel Construction estimates that the system will be rated with an R Factor of R=8.
Other Hurdles
Total time on the project, which began in October 2017, is estimated at 31 months, versus 40.
However, work on the building, in addition to another high-profile tower project, was halted by internet juggernaut Amazon.
The company is threatening its occupancy of the towers in opposition of a proposed new tax on large employers in the city. The Seattle Times reports that it’s the first time Amazon has delivered such a political move.
The council is considering what it’s calling a “head tax”—an employee-hours tax on businesses grossing at least $20 million per year in the city. This would raise an estimated $75 million annually, and the council wants to use the money for low-income housing and helping its homeless population, which is reportedly among the largest in the nation.
The tax would cost Amazon about $20 million per year.
“I can confirm that pending the outcome of the head-tax vote by City Council, Amazon has paused all construction planning on our Block 18 project in downtown Seattle and is evaluating options to sub-lease all space in our recently leased Rainer Square building,” Drew Herdener, Amazon spokesperson, said in a statement.
The company is slated to occupy all 722,000 feet of office space in the Rainier tower, and the two tower projects are currently employing about 8,000 workers.
