Arch support
The skeleton of Mansueto Library’s glass dome rises.
By Elizabeth Station
Photography by John Pitcher
Workers install steel-and-aluminum tubing—the bones of Mansueto’s glass dome.
Like the tiers of a wedding cake, scaffolding appeared over the big hole in the ground that will soon become the Joe and Rika Mansueto Library. Built to aid construction of the library’s elliptical glass dome, the structure went up in late April.
Over the summer, passers-by will be able to watch as the library’s distinctive oval dome takes shape. First, a high-strength steel-and-aluminum grid will rise from the foundation. When the grid is in place August 1, glass panels will be installed from top to bottom.
At the work site in April, a tall crane swung bundles of sleek, silver tubing—made in the Czech Republic and delivered directly to Chicago—from a truck to the ground. To create the grid, workers will bolt together more than 700 six-foot tubes and nodes, “like a giant erector set,“ explains Michael Natarus, senior project manager. Special tools have been manufactured to assemble the components.
Although Helmut Jahn designed the library, the current construction phase reflects the genius of architect and structural engineer Werner Sobek. “He takes Helmut’s ideas and does the structural calculations,“ says Natarus. Following Sobek’s specifications, Seele, the German company hired to build the dome, recently did a successful test-run of the grid assembly at its plant near Augsburg. The pieces are designed to fit “within a tenth of a millimeter,“ says Tobias Karnagel, site manager. That level of precision is unusual, but necessary for ensuring the frame bears the weight of the glass.
Seele has done steel-and-glass construction for the new U.S. Institute of Peace in Washington, DC; Apple stores in New York City and around the world; and many other projects. Two workmen on the Mansueto crew helped assemble Anish Kapoor’s Cloud Gate in Chicago’s Millennium Park, but according to Natarus, “nobody has worked on anything like this before.“
Below ground, work on the library is also progressing. When Natarus led the way down into the five-story-deep cavern that will eventually house an automated storage and retrieval system for 3.5 million volumes, the massive scale of the project hit home. The space, now mostly empty, is gargantuan, making a visitor feel like a tiny flea in the bottom of a deep, dark mixing bowl.
But the giant oval won’t be empty much longer. Fireproofing, ductwork, and construction of a corridor to the Regenstein Library are moving forward. Air-handling units, which will maintain the temperature and humidity in the book stacks, have already been delivered. A concrete slab now separates the Mansueto basement from the ground floor, the future home of a sunny reading room. The dome is expected to be finished this fall.
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- Photos of the Mansueto Library construction