Award of Merit: Special Projects Category
John G. Shedd Aquarium East Mezzanine Slab Reconstruction
Submitted by Klein & Hoffman, Inc.
John G. Shedd Aquarium
Klein & Hoffman, Inc.
Fieldstone Building Systems
Ozinga Chicago RMC, Inc.
American Hydrotech, Inc.
Reconstruction of the east mezzanine slab at the John G. Shedd Aquarium presented numerous structural and construction challenges. Located in the historic aquarium structure constructed in 1927, the slab was originally designed to function as a roof enclosure for the chiller room. Growth of the aquarium necessitated use of the mezzanine as occupied space.
Not only was the mezzanine significantly deteriorated due to the high chloride in the concrete because of the proximity of salt filters, it had a load-carrying capacity of only
0.07 psi (0.0005 MPa). This limited the functionality of the 3200 square feet (297.3 square meters) space for the proposed use required by the aquarium.
Some of the challenges of this project included the following:
- The chiller room for the aquarium, located below the mezzanine floor, was to remain operational throughout the duration of the project. High-density mechanical, electrical, and plumbing equipment was also mounted below the underside of the slab, limiting access for repair and shoring. Because of the continual use of the equipment, most of the conduits and piping could not be removed to facilitate construction.
- Because of this, the original slab—where possible—was left in place and used only as forming for a new structural slab cast above.
- The original concrete slab was supported by concrete columns; steel columns, however, supported the floor above. Developing continuity and transferring the new slab loads into the columns needed to be accomplished through nontraditional detailing due to the constraints of the existing construction and mechanical systems below.
An analytical review of the load path facilitated detailing to work within the existing construction constraints. Contractor coordination was important to minimize the relocation of existing mechanical systems to accommodate the required structural design on time and within budget.