To complete the $55 million renovation of the historic John G. Shedd Aquarium in the allotted 17-month schedule, the Building Team had to move fast to renovate and update exhibit and back-of-house maintenance spaces, expand the visitor group holding area, upgrade the mechanical systems, and construct a single-story steel structure on top of the existing oceanarium to accommodate staff office space—all while the facility remained fully operational.
To help coordinate the complex construction schedule and deal with tight working conditions along Chicago's lakefront, the team—led by Walsh Construction and Valerio DeWalt Train—modeled a significant portion of the reconstruction work, including the 24,000-sf office addition, using building information modeling software. Crane location, material staging, steel hoisting and erection schedules, and patron/staff egress pathways were all carefully coordinated using BIM.
Other aspects of the project could not be so carefully anticipated due to unforeseen conditions in the 79-year-old structure. When the aquarium's three-million-gallon tank was drained to make way for a new pool lining, the team discovered that hydrostatic pressure was the only thing holding the acrylic viewing windows in place. To avoid the costly and time-consuming process of hoisting the massive windows out of the pool during the renovation, the team devised a clever structural bracing solution that used brackets installed underwater to hold the windows in place.
The team also had to devise three custom rolling scaffold platforms to permit installation of a new theatrical tension grid and A/V lighting systems to the oceanarium's structural trusses, which span as high as 80 feet over the pools. The special scaffold platforms were designed to cling to and roll along the bottom flanges of the trusses, and to flare out as they moved toward the curtain wall, providing workers safe access to the trusses.
“This was a technically challenging project, with a passionate client and lots of demands,” said Reconstruction Awards judge Matthew H. Johnson, PE, associate principal with Simpson Gumpertz & Heger, Waltham, Mass. —Dave Barista, Managing Editor