The 2nd Avenue Residences Parking Garage showcases several primary advantages of precast concrete construction. The project highlights the design possibilities of precast components. It documents the speed of precast construction and how precast is ideal for building on tight sites with limited access. It also illustrates how precast systems can work effectively with other building materials.
Located in the Needham Crossing district of Needham, Massachusetts, the development consists of a 4-story, open-air precast concrete parking garage surrounded on three sides by a 5-story, apartment building. The garage offers 583 parking spaces including open roof-top parking. The 390-unit apartment structure surrounds two, separate open courtyards. One court features an outdoor swimming pool. The other provides theater lawn space and a fire pit.
The garage footprint is bounded on three sides by the new residential structures and on the fourth side by a public street. Each level in the apartment building is designed to have direct floor access from the structured garage. Common walls with the residential structure are designed as solid fire separation walls. Designed for self-parking, the garage provides two-way traffic and sloping parked-on ramps between floors. The sloping structure is pitched to drains. Circulation consists of a single threaded helix.
Precast concrete construction was selected for the garage for a number of reasons, according to Wes Wilson, senior project manager for project engineer Desman. “One was cost,” says Wilson. “Another was [precast] allowed long span construction and allowed us to meet the schedule. In addition, designers were able to meet the architectural design intent. There was a high level of architectural finish that had to be incorporated into the exterior precast façade elements. A specialized, pigmented concrete was used with a form liner that provided a wood-grained texture.”
A primary advantage of using precast for the parking garage was its speed of construction, agrees Chad Carr, design manager for architect Cube 3 Studio. “It set our construction time line and it fit the budget that was in place.” Carr also notes that a standalone precast parking garage, rather than a podium-type project, was able to get the density of parking they desired.
“We also wanted the aesthetics of the precast garage to mimic what we were doing architecturally on the building,” adds Carr. “The architectural challenge was to get a cohesive design between the two [structures].” This was accomplished by using the textured precast panels to mimic the wood and by finding a particular color match that worked nicely and would complement the building.
Christopher Zarba, director of sales and project development for Blakeslee, explains: “The exterior façade on the open side of the garage facing the public street includes a unique combination of textured form finishes and colored concrete to create visual interest and compliment the architecture of the surrounding residential complex. The spandrels,” he says, “feature a light sandblast finish with two types of form liner and two types of color pigmented concrete used to achieve the exterior façade aesthetic.”
The most exciting aspect of the project, according to Wilson, was seeing how the two mixed-use elements came together and how the architect was able to bring two different structure types into a similar design within the overall setting. “We had to make sure we had the appropriate separation between the two usages, including fire separation,” he adds. “The garage pedestrian connections are tied into the vertical pedestrian connections that are part of the apartment complex.”
Carr agrees. “Having the garage wrapped by the apartments with two completely different construction types was a major challenge,” he says. “We had to detail that [connection] in terms of waterproofing. More importantly, from a life safety standpoint, we had to maintain the fire rating on the residential side but still make that a constructible detail in the field.”
Determining the construction sequencing was also important. The precast garage was erected first. The apartments utilized tilt-up construction with the walls fabricated in panels, waterproofed and then tilted up into place to the garage. The two structures have a common footing, says Zarba, but the apartments are not bearing on the garage but are only separated by a thermal expansion joint.
Long Span Double Tees
The all precast garage includes precast concrete pretopped double tees, columns, beams, shear walls, lite walls, wall panels, and spandrels. Blakeslee Prestress both furnished and installed the precast components. The firm prides itself on working with the design team during the preconstruction stage to serve as a specialty contractor for the precast scope of work.
Double tees used on the garage measure 12-feet wide, 30-inches deep, and 61-feet long. All field welded connections are stainless steel. Diaphragm chord reinforcing is epoxy coated rebar. GGBFS (ground-granulated blast-furnace slag) was used on interior structural products – double tees, girder floor members, interior columns, lite walls and shear walls – to improve durability. Blakeslee’s production and batching operations also allow them to provide a .38 water/cement ratio for all products.
The tight site provided limited access for precast erection, according to Zarba. “Erection,” he says, “was accomplished with the cranes and delivery trucks inside the footprint. Close coordination and cooperation between Blakeslee and the Contractor,” Zarba adds, “proved to be key to smooth running site logistics, which allowed for advancing the precast garage erection ahead of schedule.”
Precast erection took just 22 days, from August 2 to August 31, 2017.