UB engineer's research helped build Seattle's award-winning Rainier Square Tower

Rainier square stands fully built in Downtown Seattle on a sunny day.

Rainier Square Tower, Seattle's second-tallest building, is the first building to be constructed using SpeedCore. Photo: Moris Moreno

By Peter Murphy

Published March 31, 2022

Construction of Seattle’s second-tallest building, a 58-story skyscraper named Rainier Square Tower that opened last summer, took roughly four years.

This research demonstrated the excellent seismic performance of the structural system for its use in such applications
Michel Bruneau, SUNY Distinguished Professor
Department of Civil, Structural and Environmental Engineering

That’s about 10 months quicker than it normally takes to build such a structure.

The accelerated pace was made possible in part due to ongoing research by Michel Bruneau, a SUNY Distinguished Professor at the University at Buffalo School of Engineering and Applied Sciences.

Bruneau has been studying SpeedCore, a new construction method that uses a concrete-filled composite steel plate shear wall cores instead of traditional cast-in-place reinforced concrete core, for more than a decade.

“I started working on concrete-filled steel plate walls in 2008. Incidentally, I have been conducting research on the multi-hazard resistance of concrete-filled steel tubes since the mid-1990s and on steel plate shear walls since 2002, so concrete-filled steel plate walls almost sounds like a logical next step combining the two together,” says Bruneau, a faculty member in the UB Department of Civil, Structural and Environmental Engineering. 

Seattle's second-tallest building mid-construction.

Photo: Magnusson, Klemencic Associates

This system uses a hybrid of steel and concrete, including two structural steel plates held in place with cross-connecting tie rods. The steel plates can support up to four floors of decking before any concrete is added. Once the panels are filled with concrete, the system provides strength and stability, along with the benefits of rapid completion.

SpeedCore led the Rainier Square Tower project to being awarded the 2021 National Council of Structural Engineers Association (NCSEA) Excellence in Structural Engineering prize.

“An industry transforming non-proprietary structural system was the key to realizing Rainier Square, Seattle’s second-tallest building,” NCSEA says. “The first-ever use of SpeedCore allowed construction to proceed 43% faster than traditional methods, shaving an astonishing 10 months off the original 32-month schedule.”

Magnusson, Klemencic Associates (MKA) is the structural and civil engineering consulting firm to develop the building and receive the NCSEA award. During his NCSEA acceptance speech, Ron Klemencic, chairman and CEO of MKA, recognized the importance of SpeedCore and the research contributions from Bruneau.

“Rainier Square was one of those once-in-a-lifetime projects where we were able to execute something that has never been done before.” Klemencic says. “The only way we could achieve this outcome is with the support of countless others, and I’d like to recognize a few of those: First off, the Charles Pankow Foundation for their support over the last 15 years, the American Institute of Steel Construction… and the research teams led by Michel Bruneau at the University at Buffalo and Amit Varma at Purdue University.”

Michel Bruneau.

SUNY Distinguished Professor Michel Bruneau

The American Institute of Steel Construction (AISC) began referring to the concrete-filled composite steel plate shear walls as “SpeedCore” in 2008. Bruneau’s research since then has led to several changes in design provisions.

From 2008-13, Bruneau and other researchers investigated the cyclic inelastic behavior of flexural walls they developed that had circular boundary elements. After demonstrating the walls’ ability to perform both experimentally and analytically, this research led to design provisions in the 2016 Edition of AISC’s seismic provisions for structural steel. According to Bruneau, this early work on SpeedCore helped secure funding and, eventually, made a larger impact.

“With funding from AISC and the Charles Pankow Foundation, in partnership with Amit Varma at Purdue University, we investigated at UB the cyclic behavior of T-shaped and C-shaped walls of cross-sections typically found in core-wall buildings – this is the same structural system used for Rainier Square - and determined the specific design parameters to be used for their seismic design,” Bruneau says. “This research demonstrated the excellent seismic performance of the structural system for its use in such applications, resulting in an expanded set of design provisions for these walls in the 2021 Edition of the AISC-7 standard Minimum Design Loads and Associated Criteria for Buildings and Other Structures, and the upcoming 2022 AISC Seismic Provisions for Structural Steel.”