Soldier Field in Chicago. David B. Seide Defined Space Chicago (left) and Ron Chapple photo (right).
The adaptive reuse of Chicago’s historic Soldier Field tackled complex geometry and steel construction innovations. We provided structural design services for the renovation, which consisted of a new 61,500-seat stadium bowl fitted within the historic 1920s shell of the current facility, as well as the addition of a new partially underground parking garage for 2,500 cars.
Stadium seats on precast concrete risers span between and are supported by structural steel rakers located 40 feet on center. The rakers supporting the upper grandstand cantilever 60 feet over the historic colonnades, one of the longest such cantilevers supporting crowds. Luxury suites and club seating are located on the stadium’s east side, allowing grandstand seating on the west side to be much closer to the field. The suite structure wraps around the corners of the field, cantilevering over 100 feet above the end-zone seating and providing support for massive video displays.
To control vibration in the cantilevered sections, we worked with Swallow Acoustics Consultants, Ltd. – now part of Thornton Tomasetti – to analyze the structure’s vibrational characteristics and design mitigation measures. The acoustical engineering team designed 21 tuned mass dampers (TMDs), each weighing 20 tons, to limit undesirable movement. We also developed a 64-channel permanent vibration monitoring system (PVMS) to monitor the motion of the rakers and TMDs. The PVMS was used in commissioning tests to verify TMD performance and compliance of the rakers with the vibration criteria.
The complex geometry and coordination of this project, together with the fast-track 20-month schedule, were facilitated by the use of Tekla 3D computer modeling of the structural steel frame. This allowed Thornton Tomasetti to electronically provide the fabricator with the geometry needed to fabricate each steel piece and connection. The result was a shorter design review process and aversion of costly miscues from design to fabrication and installation.
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