en.Wedoany.com Reported - At the confluence of the Chicago River and Lake Michigan, two supertall towers rising nearly 900 feet are under construction on the long-stalled Spire site. Developed by Related Midwest and named 400 Lake Shore Drive, the project will offer rental apartments with a variety of layouts including studios, one-bedroom, two-bedroom, and three-bedroom units. The plaza between the two supertall towers will mark the terminus of Water Street, featuring public art installations and spaces for residents and guests.
One of the key challenges the supertall project had to address was wind effects. Brad Young, Senior Associate Principal and Project Engineer at SOM, stated: "We focused on the upper half of the tower where the winds are strongest, ultimately achieving a win-win—creating terraces while reducing wind effects." The team optimized the stepped massing of the supertall towers' east facades through extensive wind tunnel testing, observing how air flowed across the site, particularly the strong currents coming from the west and southwest along the river. Young noted that initial testing revealed a "wind tunnel effect," where even subtle form adjustments produced significant impacts.
These adjustments allowed the team to eliminate the tuned mass dampers commonly found in supertall buildings. Young said: "Our approach is to avoid using them whenever possible through the building form and structural system." The solution employs a system of continuous belt walls and outrigger trusses, including reinforced concrete walls extending from the building core to the perimeter. A primary belt wall is located at the 44th floor, with a secondary belt wall near the top completing the system. Don Biernacki, Executive Vice President of Related Midwest, added: "The belt wall at the 44th floor is extremely complex, equivalent to constructing a massive horizontal structure 44 stories high in the lakefront area." Two pours involved 400 cubic yards of concrete, 150,000 pounds of rebar, and 12,000 square feet of formwork, requiring the precise setting of 24 openings for curtain wall installation.
The team chose to utilize the original Spire foundation as much as possible. Young pointed out that 20 rock caissons, each 10 feet in diameter, were already in place, with the supertall towers' cores positioned directly on them. Over 20 million gallons of water had to be pumped out before construction began. At peak, more than 260 workers were on site, with the team pouring concrete every three days, using BIM and drone verification to ensure precision. The project is being built by a diverse team, with Related Midwest reporting over 1.5 million cumulative work hours and fewer than 10 incidents.
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