Logan CONRAC Parking Garage
First Use of Terracotta in Load Bearing Precast Concrete Walls
Terracotta veneer on precast concrete structural wall panels clad the new Consolidated Rental Car Facility (CONRAC) at Logan International Airport in Boston. This technique was used for the first time in North America on this project to meet the variety of aesthetic and structural challenges designers faced.
The four-level, 1.2-million square-foot parking structure serves eight rental-car companies that need space to rent as many as 5,000 vehicles as well as maintain and service them. The original plan called for inset brick to complement historic residential buildings facing the structure on two sides, but the owners wanted a more contemporary look to blend with other modern airport buildings on the other two sides.
To blend these disparate aesthetic needs, designers suggested a terracotta veneer on precast panels. The combination has been used in Germany but not in America, says Camille Bechara, project manager and lead designer with Parsons Brinckeroff. The material provided the warmth and texture to complement the neighborhood structures while offering larger pieces that could create the contemporary feel requested for the other façades while creating consistency across the entire façade.
The panels feature 3/4-inch terracotta veneer sheets measuring 2 by 3 feet embedded into the concrete panels, which are 51 feet tall, 12 feet wide and 10.5 inches thick. The veneer was set into formliners and the concrete was cast over them, with added haunches on the reverse side of the panels to support the structure’s double tees. Embedding the veneer into the panels saved about $1 million, Bechara estimates.
Structural walls and H frames were designed for the facility to shift lateral load-resisting elements to the perimeter so interiors could remain open without requiring shear walls. This design provided flexibility for each rental-car company, allowing it to maximize the efficiency of its space for its operating needs. Bays are 60 by 60 foot, with interior moment frames used between columns and tees.
“We liked the flexibility that the precast concrete framing system could provide to give each company complete freedom in designing its layout,” says Bechara. “Embedding the terracotta veneer offered significant savings, and we made it work.”
The structure also achieved LEED Silver certification. Precast concrete aided this goal through its use of local materials and manufacturing, recycled materials, minimal construction waste, and other features.
Structural Precast Elements:
• 1,285 Double Tees
• 323 Girders
• 146 Columns
• 44 Seismic H and Moment Frames
• 60 Wall Columns
• 178 Spandrels
• 36 Stairs
• 11 Solid Slabs
• 132 Wall Panels