Rainier Square Earns ACEC-WA Engineering Excellence Award

The American Council of Engineering Companies of Washington (ACEC-WA) presented Rainier Square with a Gold Engineering Excellence Award in the Structural Systems category during the organization’s annual gala on March 25 in Bellevue. Completed in November 2020, Rainier Square is a 58-story, 850-foot-tall, mixed-use destination in downtown Seattle offering 1.4 million square feet of space for offices, luxury apartment homes, and retail stores.

Recognized by ACEC-WA as one of the state’s top projects demonstrating an exceptional degree of engineering innovation, complexity, achievement, and value, Rainier Square is the first high-rise building to be constructed using SpeedCore. This innovative, non-proprietary structural system uses modular, prefabricated core elements with assembly-line-like efficiency to erect high-rise towers faster, safer, and more economically. Championed by Magnusson Klemencic Associates (MKA), Rainier Square’s Engineer of Record, SpeedCore’s steel Concrete-Filled, Composite-Plate Shear Wall (CF-CPSW) panels eliminate the need to place formwork or strip and install rebar, allowing developers to build entire structures at the rapid pace of steel construction.

At Rainier Square, SpeedCore cut 10 months off what would have been a 32-month schedule if constructed with a traditional structural system. Rainier Square was erected 43% faster than usual, with four floors completed weekly, resulting in a topping-out milestone just 10 months after the first steel arrived onsite. The attendant savings in general conditions, construction financing interest, and earlier rental revenue streams were significant. The prefabrication of SpeedCore’s modular panels meant less waste, fewer onsite workers, and fewer truck trips.

In addition to SpeedCore, Rainier Square’s design includes two bi-directional, 35,700-gallon water tanks, which serve as dampers at the roof to reduce wind motion, and performance-based seismic and fire engineering. Adding to the complexity, Rainier Square’s seven levels of below-grade parking required a 100-foot-deep excavation extending 50 feet below the mat foundation of the neighboring 40-story Rainier Tower, which was built in the late 1970s. Rainer Tower was supported by an impressive temporary earth retention system provided by geotechnical engineer Hart Crowser that allowed it to remain fully occupied during Rainier Square’s excavation and construction despite both towers’ snug proximities.

With this ACEC-WA Gold Award, Rainier Square advances to ACEC’s national competition, which recognizes the industry’s top engineering achievements. Winners will be announced during ACEC’s Engineering Excellence Awards Gala on May 24 in Washington, DC.

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