Alpharetta, Ga., is a fast-growing southern city, with restaurants, shops, and office spaces that are attracting a growing population of citizens and tourists. This growth has been great for the local economy, but it was creating increasing traffic concerns. So in 2012, city leaders decided they needed a new downtown parking structure to accommodate the flow.
The new 40,500-ft² five-level parking deck is a supporting component of the master-planned Civic and Government Center and accommodates 455 cars, dramatically easing the demand for parking in the area. But this structure had to be more than a temporary warehouse for cars. “The City of Alpharetta wanted a showcase parking deck with an architectural design to match the new City Hall in its new city complex,” says George Spence, business development manager for Metromont Corp. in Dalton, Ga. But it had to be done on a fixed budget.
The architectural team chose precast concrete to address these dual needs. Precast concrete ensured the structure would be aesthetically compatible with the traditional Georgian architecture of the adjacent City Hall building, while still accommodating the schedule, budget, and structural needs of the deck, he says. “The ease of casting intricate and repetitive shapes in precast concrete panels allowed an economical way to incorporate the high level of detail required to effectively coordinate with the surrounding municipal buildings.”
To further accommodate the budget, the designers wanted to minimize the number of precast concrete pieces used on the project, without compromising the design aesthetic.
To achieve these goals, they worked with the precasters to develop a panelization system featuring a joint pattern that would eliminate individual spandrel panels supported on columns, which reduced the number of façade pieces by 30%.
To add visual appeal and structural support, they created a tall “tree” column design with branches extending to each side. The branches feature architectural details and are able to receive double-tee loads on the back side. “The resulting layout fulfilled the architectural intent, the structural requirements, and kept the project in budget,” Spence says.
For the façade, the precasters cast thin-brick insets with buff-colored exposed and sandblasted concrete to mimic the cast stone pieces on City Hall. The entry and exit points and elevator towers have a reveal pattern that simulates cut limestone block construction, suggesting a grand entrance for approaching cars and pedestrians. The structure is capped with a precast concrete cornice, accented with bands of bullnose projections at each floor level. A series of cast-in medallions was also included, some inserted directly into the brick façade and others framed in shadow boxes in the limestone-colored precast concrete spandrel.
Achieving these monumental details in a structural parking deck was no small feat, but it was worth the time spent on planning and collaboration to get it right. “Although this is a parking deck, the façade has the architectural complexities of high-end institutional building,” Spence says. “In my opinion, the Alpharetta City Center Parking Deck has the best architectural design of any parking deck anywhere.”