When designing a 21st century sports stadium, architects and engineers must create a multi-purpose facility that can meet a wide range of needs. To accomplish this, designers and contractors have turned to precast concrete building components for both architectural and structural applications. Precast concrete provides a consistent, durable solution that increases productivity for all phases of the construction process.
By Kirk Stelsel
For four weeks in June and July, the world’s focus was on South Africa for the 2010 FIFA World Cup. Soccer’s global draw is immense. It’s estimated that 700 million viewers tuned in for the final match – all of whom saw the flexibility and beauty of precast concrete, even though they probably didn’t realize it.
Soccer City Stadium in Johannesburg, South Africa, was designed by Populous and Boogertman + Partners to be a symbol of the host country and the continent. Meant to resemble a traditional African pot known as a calabash, the unique look required an equally unique product to bring the design to life (see Figure 1).
Site challenges for this structure included strong winds and dusts from nearby mines that can quickly erode facades and the sheer size of the 90,000-seat facility. The answer was to create a high-tech facade composed of precast panels reinforced with glass fibers. The outer skin spans 51,430 yd2 (43,000 m2) and includes a total of 2,100 modules that contain 16 precast panels each. The concrete mix allows the panels to be lighter than traditional precast cladding and maintain an acceptable strength without sacrificing aesthetics.
Roman ruins to modern marvels
The use of concrete in stadiums stretches back as far as the Roman Empire, which relied heavily on concrete. The Roman Colosseum, for example, constructed in 70 to 72 AD, still stands today.
As the architectural, engineering and building trades have advanced, so have the structures that house sporting events. Relentless innovation and an ever-increasing scale have led to venues that dwarf those of yesteryear in size and design. The modern stadium is a multipurpose facility that can host a sporting event one night and a large-scale spectator event or concert the next. It helps enhance its community and increase economic revenue.
In order to meet these multiple demands effectively, stadiums must possess a variety of attributes including an aesthetically pleasing look; family friendly interior, including ease of ingress and egress for children and disabled fans; design flexibility; abundant access to amenities; and the ability to comfortably and safely house large crowds. The almost universal answer for modern sports venues has been precast concrete components.
Risers, rakers and more
Traditional precast concrete products for stadiums include: risers; raker beams; columns; a variety of structural and architectural wall panels; spandrels, hollow-core planking; and double-tee beams. These flexible components can provide nearly limitless options for architects and engineers.
The use of precast beams and flooring allows contractors to quickly assemble the infrastructure, time the arrival of pieces to match installation schedules and reduce the total amount of material required for load-bearing walls. As the structure is completed, just-in-time precast delivery also provides more construction site workspace for support crew and equipment. Units such as concourse or vomitory walls offer a durable surface that can withstand constant battering by fans, concession carts and other small vehicular traffic. And architectural wall panels are used as an ode to a classic look or to create a new one.
J&R Slaw Inc., a manufacturer of precast concrete in Lehighton, Pa., has done stadium work for clients ranging from high schools to professional sports teams. Slaw’s portfolio includes the Met’s Stadium, the new Meadowlands Stadium, and PPL Park, home of Major League Soccer’s Philadelphia Union. “I think the most obvious advantage is these products are made in a plant, and you’re able to control the quality of the product a lot better,” said Dave Thomas, J&R Slaw project manager. “I can’t imagine trying to pour a 4- or 5-ft (1.2 -or 1.5-m) vertical wall in the field and have it turn out as nice as it would in a precast plant.”
The use of precast stadium risers allows designers and general contractors to create more complex geometries in seating bowls, including more seating levels, suites and boxes to increase revenue. In some cases, upper levels must be cantilevered to increase capacity without moving fans too far from the action.
For PPL Park, J&R Slaw poured four to five risers a day for the project, turning over the forms every day. In total, the stadium required 406 risers, as well as 52 field walls and 43 smaller knee walls (see Figure 2). “Our engineering drawings were laid out so well that they knew where every piece fit, and they would order their pieces as the construction of the stadium went around in a circle,” Thomas said. “They knew exactly what pieces they’d want on their next load.”
Kerkstra Precast in Grandville, Mich., helped Hope College in Holland, Mich., meet an aggressive timeline by creating a total-precast solution for its Van Andel Soccer Stadium. The project’s timeline, just nine months, led the project designer to think outside the box. The precast structural frame was chosen due to its durability, quality and aesthetics, as well as its ability to meet the demanding schedule (see Figure 3).
All precast framing was produced and erected in less than 10 weeks, and the project was completed four weeks ahead of schedule. In total, it features 9,500 ft2 (883 m2) of precast stadium risers; 700 linear ft (213 linear m) of precast beams; 420 linear ft (128 linear m) of precast columns; 1,200 ft2 (111 m2) of precast spandrel panels; 2,800 ft2 (260 m2) of solid precast panels; 1,200 ft2 of interior solid panels; and 2,150 ft2 (200 m2) of solid precast slabs.
Speaking about the precast Kerkstra provided, Jim Hoekstra, director of construction with GDK Construction, said, “Kerkstra’s detail in documentation, efficiency in production and installation, and concern for quality helped expedite and shorten the construction timeline.” According to Greg Kerkstra, president of Kerkstra Precast, “The contractor has to align themselves with a dependable, on-time precaster that provides a quality product. Once they do that, they can concentrate their efforts and time on other parts of the project and leave this part to the precaster.”
Right on Target
Stadiums are a key part of the success equation when it comes to professional sports. In Minnesota, the Twins were stuck playing in the aging Metrodome, which was designed for multiple sports rather than specifically for baseball. With Major League Baseball (MLB) considering disbanding the team, the city, the Twins and MLB came up with a plan for a new, baseball-specific stadium. When architectural firm Populous and engineering firm Walter P Moore began design work, it was quickly determined both wanted to use precast elements throughout.
“Architecturally we wanted to use a very large, patterned natural stone on the exterior of the building, so those large pieces would have been difficult to set as a traditional, load-bearing masonry,” said Bruce Miller, principal, Populous. “The precast solution that we came up with allowed us to use those large pieces, allowed us to get them erected quickly, and it was a cost-effective solution.”
Justin Barton, an associate with Walter P Moore, served as project engineer on Target Field. According to Barton, the use of precast provided a number of advantages including speed of erection, an overall quality feel, and the ability to span 42.5 ft (13 m) between raker bays. In addition, the construction time was reduced even further than normal through the use of an innovative lifting mechanism (see Figures 4 to 6).
“One of the things they used on this job that we had never used before was a suction lift, as opposed to the typical embedded lifting devices,” Barton said. “That seemed to work really well in terms of getting units up and less crane time per lift.” The device, produced by Aerolift Industrials BV, is commonly used in Europe, but Hanson is one of the first to use it in North America. Its capacity of 15 tons (13.6 tonnes) allowed crews to lift many of the pieces into place with a 30% increase in productivity and set as many as 30 to 50 pieces a day.
The precaster chosen for the job was the Maple Grove, Minn., facility of Hanson Structural Precast. Hanson produced 76,500 ft (23,320 m) of risers, enough to seat 39,500 fans; 4,600 ft (1,400 m) of beams; 800 ft (244 m) of columns; 21,500 ft (6,553 m) of double tees; and 5,000 ft (1,524 m) of hollow core plank. The Hanson facility spent 12 to 14 months casting pieces for the stadium, and another eight to nine months erecting product on site.
“Hanson was under contract for the TCF Bank Stadium at the University of Minnesota when pricing and construction were announced for this project,” said Matt Westgaard, general manager at Hanson Structural Precast. “We’ve participated in other construction projects for major sports stadia in Minneapolis/St. Paul with Mortenson Construction. We’ve had an ongoing relationship with them, which we value.”
Kelly Mansell, project manager for Mortenson, was very pleased with the results and the product that Hanson provided. “I think one of the reasons you always look to the precast stadium is it’s something you can fabricate off site and set in a fairly fast manner,” Mansell said. “We got a great finish on the product; I think it’s some of the best finish we’ve seen.” Mansell attributed the aggressive project schedule to the ability of precast to manufacture pieces year-round, which is particularly important in Minnesota where the weather changes dramatically between seasons.
The Target Field project faced a number of unique challenges that had to be overcome. In addition to the Minnesota Twins site being smaller than most MLB ballparks, it had an active railroad line running through it that needed to remain open. Hanson provided precast to overcome the railroad challenge. “Hanson did more than just the stadium, Mansell said. “We had hollow-core and double tees over the railroad to cantilever out over that part, and that was probably some of the trickiest work as far as scheduling. A lot of work went into how we were going to erect that without messing up the railroad for more than a couple of hours at a time.” Mortenson Construction used a combination of cast-in-place girders with precast double tees to span between girders. By using precast, the rail line was never shut for more than two to three hours at a time.
In April, the Twins kicked off the 2010 season in their new 39,504-seat stadium with a win over the Boston Red Sox. “We know that the Minnesota Twins will be pleased with what the stadium offers fans in product quality, lifecycle and duration of precast for their stadia sections,” Westgaard said.
More than meets the eye
While precast concrete has become the product of choice when constructing stadium infrastructure, the options it provides stadiums extend well beyond design and structural flexibility. The new Yankee Stadium, for example, used precast concrete to create a stormwater detainment system to collect excess rainfall under its parking garage to prevent a potential overload of the storm sewer system.
The concrete was cast by the Oldcastle Precast plant in Middle Island, N.Y., for Phase 1 Group Inc. General manager George Schramm, a longtime employee, got the job after the plans had originally called for cast-in-place concrete. “Gerard Petri of Phase 1 Group asked Marc Ficken, one of our sales reps, if we could precast the detention tanks for more efficient installation,” Schramm said (see Figure 7). “We said we could put something together, and were grateful for the opportunity to help him with his project. We had done a couple other detention systems in schools and other
projects, but these were much larger ones.”
When the Greensboro Grasshoppers in South Carolina needed something to set themselves apart from other minor league ballparks, they turned to precast. Minor league baseball is not known for its star players; fans come more for the atmosphere and experience.
While they pale in comparison to the size of their major league counterparts, minor league stadiums must create a fun, family-friendly atmosphere despite their compact sizes and budgets. To achieve this, one tactic employed by the Greensboro team was to situate six massive baseballs, weighing more than a ton each, outside the stadium (see Figure 8). The pieces were cast in halves and transported to the stadium where they were epoxied together and painted to resemble baseballs.
In Blacksburg, Va., Virginia Polytechnic Institute and State University (Virginia Tech) was looking to do more than just match the existing buildings on campus with its new Hahn Hurst Basketball Practice Center: it wanted to impress.
Local precaster Smith-Midland hand-built custom wooden forms for exterior wall panels with the imprint of basketballs, the Virginia Tech logo and the school’s seal cast directly into the concrete (see Figures 9 and 10). “The forms took a couple of weeks,” said Ashley B. Smith, president and COO. “We had to do a mockup and send it down to Virginia Tech for the owner to approve, because they obviously wanted to see what it looks like before they had basketballs and VT logos around the entire building. To actually produce the panels took about eight weeks.” Smith-Midland was also able to match the look of existing structures on campus.
“If you’ve ever been to Virginia Tech, they have what they call ‘Hokey Stone’ all over campus,” said Matthew Smith, vice president, sales and marketing. “So they incorporated the Hokey Stone into this practice facility and then our panels blended right in.” The panels were designed by Tae Jung, an architect with Cannon Design. The inspiration behind the design included incorporating the keys of a piano and the movement of a basketball into the panels, both of which have an affinity in terms of back-and-forth movement, along with the Virginia Tech logos and seal.
When the award-winning project was completed, it exceeded expectations. “We had a really good reaction,” Jung said. “One school official gave us a really interesting compliment. He thought it’s a really nice meeting between the movement of a basketball and the architectural language, and it’s really well-balanced.”
When it comes to the mega stadiums of the 21st century, the demands on architects, engineers and contractors have never been greater. Whether it’s a look and feel that transports fans to a bygone era, a cutting-edge facility that breaks new barriers or a combination of both, precast concrete is being called on to complete the task. From structural to architectural and underground to groundbreaking, precast is helping complete the project on schedule and on budget while providing consistent quality and unmatched durability.
Kirk Stelsel is communication manager for the National Precast Concrete Association.