Officials at Bridgeport Hospital in Bridgeport, Connecticut, knew they had to address parking issues before they could address other needs for a new hospital facility they planned to build. The new building would need space for employees’ and visitors’ cars while eliminating some of the available spaces by being built on the site. To alleviate these concerns, designers created a four-story, 150,000-square-foot total-precast concrete structure that was erected quickly before construction on the main building began.
“We built the garage first, because the new facility was going to consume part of the available parking while requiring more spaces itself,” explains Dave Carlson, project engineer at Spiegel Zamecnik & Shaw, the structural engineer on the project. “Using a total-precast concrete structure is a natural in our environment in the Northeast. It’s cost-effective and offers good durability and longevity.”
The structure’s precast concrete system comprises double tees, girders, L-beams, columns, shear walls, column walls, wall panels, spandrels, stairs, slabs and precast planters. A total of 450 pieces were cast, and all were erected within six weeks in the spring of 2014.
Blakeslee Prestress Inc. fabricated and erected the components, providing design-assist services during the project. “The project team was familiar with precast concrete, and we brought Blakeslee in early to help us optimize the design,” Carlson says. “We developed our BIM design to produce the overall design, and then we compared that to Blakeslee’s BIM design to develop special component breakdowns and efficient connections.”
That eliminated any issues to resolve at the shop-drawing stage, he notes. “Everything had already been worked out. The time required to get submittals prepared was greatly shortened.”
The process was complicated by the structure being built into a sloping site near the hospital complex’s entrance. This necessitated creating complex geometries and shortening the lowest and top levels to half-levels to align with the grade. Drivers enter on the second level and travel both down and up to access parking spaces.
The structure sits on a cast-in-place concrete foundation, which was made more complicated by the sloping site, he notes. “There was a lot of complex interaction between the foundation and the precast concrete components. Working early with Blakeslee ensured we found the most effective way to create those interfaces and prevent construction from slowing down.”
The exterior spandrels were cast with a white cement mix and received a light sandblast with some rustication. “Getting the right color was very important, because the hospital wanted a good look for the entrance to the campus that was also cost-effective,” Carlson explains. “We worked very hard to get the right blend, because they wanted an appearance that was whiter than was typical.”
The extra work resulted in a cost-effective design that presents a strong appearance at the hospital’s entrance while providing a key amenity that will be ready to go when the new addition to campus facilities is completed. |