The Niles North Aquatics Center is a $15 million addition and renovation to Niles North High School. The building achieved LEED for Schools Gold and uses 44 percent less energy compared to a standard code-compliant building of similar size, resulting in annual energy savings of 31.5 percent.
IMEG provided structural engineering design for the project, which renovated the 48-year-old existing pool to create a community “warm” pool and provided an addition to house a competition “cold” pool.
A major component of the renovation of the existing 14,750-SF pool building involved the existing roof structure – long span steel trusses supporting steel beams – and the steel roof deck. These elements were unpainted, and a ceiling above the pool had trapped the unconditioned, humid pool air, leading to severe corrosion of the steel. In addition to replacing all the roof deck, all steel beams were replaced and long span trusses reinforced to support the weight of new rooftop mechanical units. The final design of the renovated space eliminated the ceiling, with the exposed steel protected with paint.
The 25,500-SF addition – comprised of a new two-story building with an eight-lane stretch pool with movable bulkhead and seating for spectators and athletes – presented many structural challenges, starting with the distinguished curved ceiling, one story high at one end and two stories high at the other. Steel joists were chosen because they were economical, provided the light and airy feeling that the architect was trying to achieve, and were easy to fabricate in the curved shaped. However, because of the nature of a curved shape, the joists needed to be designed as pinned on one side and as a roller on the other side. The joists are now free to move in a parallel direction to accommodate horizontal deflection due to snow load.
The second challenge was the angled columns and beams on the south end of the building, where the joists curved down to form the one-story space. Supporting the end of a joist on an angled column and beam adds significant moment to the column, increasing its size. To help keep the column size small, the architect allowed for the addition of a vertical column hidden behind the angled column to brace the column and reduce the moment. In order to to fabricate the joist seat as flat and also allow for the roller connection on this end of the joist, a steel seat was fabricated at each of the joist-bearing locations to allow for easy erection of the joists.
The third challenge was protecting the acoustic deck in the humid environment. To accomplish this, the fiberglass acoustic batts were individually encapsulated and the deck was galvanized and a Tnemec primer was applied in the shop. The final coat of Tnemec paint was added in the field over all the exposed steel to protect it from the humid air.
Leaving the steel structure exposed keeps the space open and comfortable and provides a dynamic look to the building, which has won awards for its design, energy efficiency and design team collaboration. Completed in 2013, the addition and renovation improves competitive and educational swimming programs, promotes community participation, and enhances safety. The facility houses a year-round competitive swim program hosted by the school district, Illinois Swimming, and USA Swimming.
Structural, Construction Administration