From the outset of the project, the design team for the Worcester Polytechnic Institute (WPI) knew the structure needed to be durable enough to withstand the potentially corrosive pool environment, and be able to accommodate the 110-ft (34 m) spans across the pool. They initially considered steel trusses, but ultimately realized it wasn’t the most resilient choice. Eventually they chose precast concrete thanks to its durability, mass and shape flexibility. The use of precast concrete to solve this challenge not only made the project stronger but aesthetically unique, and as a polytechnic institution, the interesting engineering approach was of great value to the client.
Knowing it needed to work with precast, the design team still recognized that creating the long span precast bents as one piece was not practical. Instead, the bents were designed as five separate elements spaced at 14 ft-9 in. (4.5 m) on center spanning 110 ft (34 m) across the pool. The smaller pieces meet requirements for shipping, weight and size, and splice locations were chosen to minimize the demand on the connection and to avoid heavily reinforced areas.
Precast concrete double tees were placed between the bents to support the four-court gymnasium above. A large circular opening for the duct work was also added to maximize the space above the pool and provide a clean profile for the ceiling.
Along with delivering a clean open design, the precast concrete is durable enough to withstand the harsh pool environment -- other material choices would have degraded over time. Precast reinforced concrete is typically the best type of structural framing material to respond to this type of environment.