St. Regis Chicago

Team

Architect

bKL Architecture, w/Studio Gang Architects, Gensler, and Loewenberg Architects

Contractor

McHugh Construction

Stats

PROJECT TYPE

Mixed-Use

COMPLETION

2021

PROJECT SIZE

1.97 million ft²

MKA ROLE

Structural Engineer

Chicago, IL
St. Regis Chicago

Rising 1,200 ft above downtown and representing Chicago’s third-tallest structure, this mixed-use residential and hotel building is comprised of three interconnected, extremely narrow, vertical volumes of 100, 75, and 50 stories. Wind analysis optimized a 28-ft-tall blow-through level to reduce the building’s cross-wind lateral response by 24 percent.

A Slender, Resilient Design for the Windy City

Tasked with designing a tower that soars 1,200 feet into the sky, stands just 90 feet wide, and is located in one of the windiest cities in the world, MKA incorporated multiple engineering innovations into St. Regis Chicago’s design.

MKA’s chief concern was to design a tower resilient enough to withstand Chicago’s seasonally powerful windstorms without experiencing large cladding deformations, elevator shutdowns, and motion sickness among the building’s occupants.

It sounds counter-intuitive, but St. Regis Chicago’s design allows wind to blow directly through the building at Level 88. This double-height, blow-through floor confuses and reduces wind forces, resulting in a 20% reduction in overall building overturning forces.

Meanwhile, six Tuned Liquid Damper Tanks holding 90,000 gallons of water are located at the roof and the blow-through levels. This added dampening reduces building accelerations by 70% simply by tuning the liquid’s sloshing motion to counteract the building motion.

Finally, a buttress-coupled, dual-core lateral system engages the full width of the building, capturing the broadest possible stance to resist the wind, while providing minimal disruptions to the condominium and hotel programs.