The Redevelopment of Block 37 is a significant mixed-use retail, entertainment, office and transit project located in downtown Chicago. Thornton Tomasetti is the structural engineer for three segments of the project, working with three different owners and two architects.
The 17-story Media Office Tower encompasses 550,000 square feet of Class-A office space with one basement level and includes a street-level, state-of-the-art television and radio station broadcast and operations center. The original 1920s mid-rise building on the Media Tower site contained three sub-basement levels. When the building was demolished, the below-grade structure and debris from the demolition was left in the basements, making it difficult to excavate the site for the new Media Tower. The new building reused many components of the original foundation, including hand-dug rock caissons and portions of the perimeter basement wall.
The Retail portion of the project comprises 70% of the site and utilizes an up-down construction technique. Up-down construction was chosen to accelerate the project schedule by enabling below-grade and above-grade construction to happen simultaneously. Below the 400,000-square-foot, five-level retail development is a four-level, below-grade concrete basement that provides space for retail, parking and transit. Excavation of the four-level basement was complicated by the need to keep local services active. An earth retention system was selected and designed to protect the active freight tunnel located eight feet from the property line, the transit tunnels, and a pedestrian tunnel during excavation of the four sub-basements.
Location: Chicago, Illinois
Owner: Media Office Tower: Golub & Company Retail: Joseph Freed and Associates Transit Center: Chicago Transportation Authority
Architect: Media Office Tower: Perkins + Will Retail / Transit Center: Gensler
Area: Media Office Tower: 17 stories, 550,000 sf; Retail: 5 stories, 400,000 sf above transit area; Transit: 4 below-grade levels
Completion Date: 2009