Inventive structural design pulls out all the stops to make this stadium a success
Unique in capacity, capability and character, TD Ameritrade Park Omaha opened in June of 2011, enhancing this Midwestern city's reputation as one of America's great sports communities. The new 24,000-seat baseball park had to be designed and built as a hybrid of different stadia types to accommodate multiple sports and various community events, on a tight schedule driven by the opening day of the 2011 College World Series.
To help meet the ambitious schedule for the project, it was separated at the start into two components for structural design: the grandstand structure and the lower seating bowl/outfield structure. This allowed two teams to work independently during design development. HDR, as Structural Engineer of Record, undertook the lower seating bowl and outfield structures, while consultant Thornton-Tomasetti focused on the grandstand.
The site presented issues with high groundwater and soft alluvial soils. HDR's structural innovation on the project was the use of a mechanically stabilized earth wall system to retain the lower seating bowl earth fill, in lieu of structural concrete retaining walls and footing. Since this option avoided the need for scaffolding and formwork, this alone saved the project over $500,000 and three months of time.
Due to poor soil, the site required a surcharge at all locations where the soil would support a slab on grade, or seating bowl. The surcharge duration in many locations would have caused a significant delay in completing critical path activities on the project. The project team determined that using styrofoam to fill locations in lieu of the surcharge would eliminate any delays. After construction, the earth form settled as planned, leaving the seating supported on pylons. Then the grandstand was erected, a curved structure of approximately 3,000 tons of structural steel, with trusses cantilevering 35 feet to support the upper precast seating bowl.