Builders Solve Calatrava's Florida Polytechnic Puzzle
Builders of a glass-sheathed Florida college building—topped by a 250-ft-long skylight shading system with 94 louvered arms that raise and lower to track the sun—say they could not have successfully executed the unusual design without intense consultant-contractor cross-pollination. The $60-million building nearing completion in Lakeland, designed by architect Santiago Calatrava, is on time and on budget thanks to the teamwork, they say.
Designed as the signature element of Florida Polytechnic University's still-emerging campus, the 162,000-sq-ft Innovation, Science and Technology Building (IST) stretched the team's envelope of experience. "Every corner we turned, there was something that required close attention," says Joey Ottman, with Alfonso Architects, the project's Tampa-based architect of record.
Construction manager Skanska USA, Tampa, is credited with breaking down traditional silos of silence between the design and construction team.
Calling it an "open, collaborative effort," Roger Webb, operations manager for Baker Concrete Construction—the specialty contractor that delivered the exposed concrete structures inside the building—says Skanska "engaged the design members into the construction process more than I've ever seen."
To that end, Skanska vice president of operations and project leader, Chuck Jablon, eschewed an emphasis on contractual responsibilities in lieu of a broader, shared approach to finding solutions to design challenges. Specialty contractors and sub-designers participated early in the project in a design-assist role.
"We worked with the architect and the consultants from conception," says Jablon, noting monthly trips by various team members to Calatrava's New York City office. "All of us were a team that worked as one."
The facility will serve as the first and central building for the campus of Florida Polytechnic University, which was created in 2012 as a new state institution—and the only one dedicated to a curriculum of science, technology, engineering and math. The two-story reinforced concrete structure—which includes labs, classrooms, offices and common areas—is surrounded by a system of 84 connected pergolas that visually enclose the terraces that encircle the building.
Skanska's contract also included construction of a 5,000-sq-ft central energy plant housing four 600-ton chillers and four cooling towers, all controlled via "cloud-based" systems.
Starting at the Top
The need for the close-knit interaction was apparent early, starting with the main challenge posed by the 3D puzzle-like design of the rooftop shading system. To control daylight entering the glass-covered structure, the architect opted for a system of louver arms as long as 62 ft that automatically raise and lower, in an arc, with the passing sun.
"The movement of the louver arms is integral to the design functionally, technologically and symbolically," says Frank Lorino, chief architect of Calatrava's New York office.
That movement is significant in other ways, too. Each louver arm is engineered with the capability of a maximum upright position equal to approximately 65˚ above the horizontal plane. In the fully lowered position, the operable louver arms will rest at 48˚ below the horizontal plane. Traveling that total 113˚ distance will take between seven and 10 minutes.
"Symbolically, the operable louvers help the building create a strong identity for the new university campus," says Lorino. Thanks to this, the team needed to be able to construct the kinetic system without evident compromise to the design concept, he adds.
The louvers, which control solar heat gain and regulate light levels, were designed to eventually accommodate a system of photovoltaic tape to generate power for the campus, says Skanska. According to architect Lorino, the IST's operable system is roughly twice the size of the one Calatrava designed for the Milwaukee Art Museum. When the louver arms are in their full upright position, the two-story Florida building measures 130 ft from bottom to top.
Originally, the architect proposed building the system as a pair of matched structural-steel components—consisting of 47 arms each—that would move separately via hydraulic equipment situated at each end. But the approach proved unfeasible because the system would have generated extreme loads on the structure, says the structural engineer.
"The accumulated force would be so great that you [would have to have] special structures to transfer load down to the foundations," says Sherry Yin, project manager for Thornton Tomasetti, New York City.
Yin adds that such a system also would have been too costly and, also, difficult to maintain. Instead, Thornton Tomasetti and fabricator-erector MG McGrath set out to devise an alternate approach. "We were trying to come up with a concept from an engineering standpoint that would work structurally," says Mike P. McGrath, vice president of operations for the Maplewood, Minn.-based contractor. "There was a good year of that."
Eventually, the two firms proposed constructing a system composed of each custom arm unit operating independently via 94 individual hydraulic cylinders, designed by Atlantic Industrial Technologies, Shirley, N.Y., with support from McGrath. Also, McGrath proposed using aluminum, instead of steel, because of lower weight and reduced maintenance.
As a result of that change of the system's design, "Our structure [is] simplified, more economical and more structurally sound," says Yin.
Though aluminum lightened the load, the fact that the material is less stiff than steel meant "we had to keep our eye on the service requirement for deflection," says Yin.
After McGrath proved the aluminum could meet the deflection criteria, Thornton Tomasetti engineered the spacing between the stanchion structures supporting the arms with a 3-ft minimum to further guard against any two arms hitting each other as a consequence of possible wind-induced deflections.
Supporting the entire rooftop system is a concrete ring beam that encircles the interior of the IST's common areas. Originally designed as structural steel, Skanska initiated a change to reinforced concrete for the ring beam, which measures 72 in. deep and 30 in. wide.
Tolerances for all items, including erection, assembly and fabrication of the metal systems, was 1/16th of an inch, says Jablon. For instance, each of the 84 pergola frames—comprising 104 rods each—measures 39 ft tall by 50 ft in length—or nearly 70 ft from end to end, says McGrath.
"You run that 16th of an inch over 70 ft, and [the required tolerance] is nowhere near any typical industry standard," he says.
To meet the standard, McGrath used what he calls "robust 3D modeling." The firm fabricated the pergola pieces in Minnesota and preassembled them at a facility in Bartow, Fla., before installing them on site.
The arms and pergolas proved simpler to construct than to engineer. "The pergola and louver arms required significant interaction to solve myriad technical problems, and to do so within the budgetary restrictions," Lorino says.
Once achieved, though, construction proceeded more quickly. "That [design and fabrication] process was tedious, but once approval was given, it went up pretty quick and easy," says Ottman. "Believe it or not, there weren't a lot of issues."
Exposed Systems
The Polytechnic building is an example of expressed structure. Formwork for the exposed and curved concrete was custom built, says Baker Concrete, and the firm relied on its most skilled carpenters, brought in from across the state to build the formwork on site.
"It was one-time-use stuff mostly," Baker's Webb explains. "So we did a lot of full-scale layout and just cut the wood.
"We did mock-ups religiously out here," he adds. "It's how we set expectations with everybody."
Several hundred "perfect portals," as Webb calls them, line the building's corridor that separates classrooms on the outer walls from lab spaces and common areas in the central space. For these, Baker cast them as two columns, and then used a wall form with inserts to create the angled connection between them.
Constructing the web-like network of raker beams that serve as an interior focal point of the building's front and back entrances was considerably more complicated, requiring extra oversight from Thornton Tomasetti and Alfonso with regard to formwork design, shoring methods and concrete curing methods.
Designing this concrete formwork proved to be "a very tedious process," Ottman says. "I can't tell you how many concrete formwork drawings I reviewed."
Also, hiding the construction joints for the grand staircase at the front entrance took considerable planning, with the team ultimately settling on a construction sequence of building the upper section first, followed by the lower portion and finally the middle.
"Those grand stairs were amazingly difficult to make work," Ottman says. It required "almost surgical construction so that at the end it looks like one piece."
On Schedule
Going into the project, the team was well aware of the constructibility challenges on some of Calatrava's other projects. With Polytechnic's first class of students scheduled to arrive this August, and with no extra state funding available, builders couldn't let the project's schedule slip or its cost balloon.
"That fueled us to get this right at every step," says Ottman. "Everybody bought into that."
"There was a schedule pressure, but not to the expense of the quality on the job," adds Baker's Webb. Schedule "was definitely a secondary priority here."
That's because building an accurate realization of Calatrava's vision was always the goal, says Skanska's Jablon. "He's as happy as we are that we're delivering it," he adds. "The baby lives."
