Workshops: Control of Wind-Induced Acceleration Response of 80-Story NEMA Chicago: A Case Study

Farshad Berahman
Principal
Magnusson Klemencic Associates, Seattle

NEMA Chicago is a recently completed addition to the skyline of Chicago, rising 273 meters tall in the South Loop. NEMA is Chicago’s tallest all-residential concrete structure which has a pure architectural form that embraces the historical city while looking to the future of urban living. The tower has a column free interior spacing providing residents of the 800 units stunning views through floor-to-ceiling glass spanning between wide structural bays. The architectural vision is achieved by employing innovative engineering solutions to ensure efficiency while achieving the necessary levels of comfort and safety for tenants.

Stability of the tower is provided by the central core and outriggers. The building’s program required stacked corridor openings through the outrigger walls. To overcome this requirement, a relatively unique steel embedded outrigger system was used. The impact of column shortening and temperature loading on exposed concrete columns had to be considered carefully and led to some additional consideration in the design of the structure and cladding.

The design approach used to synchronize architectural and engineering solutions delivers a building with flexibility in unit layouts throughout the tower. In this regard, the building has a structural system that includes a unique outrigger configuration. Additionally, potential susceptibility to human perception of wind-induced acceleration required several supplementary damping systems, including Visco-Elastic Coupling Outrigger Damper (VCD), Tuned Mass Damper (TMD), and Tuned Sloshing Damper (TSD).