The project posed a major structural challenge: Convert the below-grade theater and parking garage into a health club with a swimming pool without compromising the 66-story luxury building above. The existing sloped concrete and steel floors of the theater and garage held back 75,000 tons of soil below Michigan Avenue, making them structurally vital and ruling out the option of wholesale demolition of floors prior to new construction.

The second challenge was completing the project on a tight deadline and limited budget. The Structural Group was brought on to the project late, after the contractor found the initial scheme too costly. Not only were we asked to redesign the structure within budget, but we also had to do so without any delay to the design/construction timeline.

To tackle the main structural challenge, The Structural Group detailed new floor slabs with composite steel frames that could resist the existing loads and connect the floor diaphragms at the correct elevation. Once the new construction was in place, the existing floor could then be demolished from below.

That was far from the only complication, however. The design called for a swimming pool on the lower level, interrupting the existing floor diaphragm. To accommodate this, we stepped in to redesign the pool as a structural element, transferring the diaphragm forces through the pool walls and floor.

This scheme entirely eliminated the need for temporary shoring in the floor construction, which lowered the excess costs.

The scheme The Structural Group designed solved the project’s technical complexities, and it saved the owner hundreds of thousands of dollars in shoring costs through its efficiency.

Despite the initial setbacks, we were able to quickly understand the challenge, pivot the design and provide an alternative structural solution, getting the project out for permit within the six-week deadline as promised.

The Equinox Fitness Center project was such a success that the client has since selected TSG for dozens of other retail, residential and office projects.