St. Armands Circle in Sarasota, Fla., is a favorite destination for tourists and locals alike. Located on St. Armands Key along Florida’s Gulf Coast, it offers an open-air shopping market, restaurants, and festivals throughout the year. The main streetscape has been extensively updated over the last 10 years; however, parking options were limited and in need of an upgrade.
The City was facing pressure to address the parking situation quickly, to accommodate the Christmas 2018 crowds. That led the City to plan a $12 million, four-story, 482-space parking structure built entirely of precast concrete.
Accelerated delivery was just one of many goals that precast concrete helped achieve on the project, says Mark Santos, parking practice builder for Kimley-Horn and Associates. In addition to expanding parking options, the new garage had to provide complement the landscape, and achieve a Silver Parksmart rating, which is the second-highest rating offered by Green Building Certification. “The owner was extremely interested in durability because of the project’s proximity to the Gulf of Mexico,” Santos says. Construction also had to be minimally disruptive to adjacent businesses and residents.
“Our biggest challenge was settling on a design that balanced creating an efficient structure on the L-shaped footprint while incorporating an aesthetically pleasing facade,” he says.
Waterproofing admixture reduces permeability
The parking structure’s design features a soaring, white precast concrete structure, with dramatic exterior cascading stairs, a metal mesh twisted facade that catches the sunlight, and solar panels on the third level that provide electricity and shaded parking. A cast-in-place topping was implemented on the two-main parking bays for increased durability and to minimize sound for the adjacent residential neighbors.
To increase water proofing in the highly corrosive seaside environment, the precast concrete producer included BASF MasterLife 300D admixture in all panels. “It reduces concrete permeability, reduces water penetration, and helps seal hairline cracks,” explains Josh Cameron, plant manager for Coreslab Structures. The precast concrete producer recognized that the material, which is commonly used in water treatment plants, would bring added value for this project, he says. “Coreslab found it to be easy to work with, and it had no negative side effects to our pouring or finish of the concrete.”
Cameron also notes that the design’s zigzag joints presented a compelling puzzle for his team. “As precasters, we are always challenged to ensure joints and miters are perfectly square,” he says. They knew they had little room for error when casting these panels, so the layout on the forms was triple-checked prior to casting. “We were very happy when these erected and everything matched up so well.”
Once the precast concrete elements were cast, the precast concrete producer worked closely with the design team to coordinate their delivery in a sequential manner. This helped the team avoid the typical construction issues associated with the cast-in-place construction. “The biggest challenge was shipping the 60,000-pound panels to the site,” says Vern Smith, sales manager for Coreslab. Delivery of the precast concrete elements to the island had to be coordinated with the City and the Florida Department of Transportation (FDOT) to accommodate both bridge weight limits and traffic patterns. Smith notes that the strong collaboration minimized traffic disruption, with brief partial street closings coordinated well in advance. Once on site, the contractor was able to rapidly erect and complete the project, meeting often intricate design specifications.
“Finishing on time and on budget was truly a success for this team,” Smith says. “This project could not have met the timeline that the owner needed using any other construction system.”