By Jenny Jones
Engineers use computer modeling to achieve the distinct facade of the new 65,000-seat soccer stadium in Basra, Iraq.
The stadium's facade is designed to recall the undulating bark of date palm trees and the texture of traditional woven goods found throughout Iraq. Courtesy of 360 Architecture, Inc.
January 14, 2014—In 2009, the Iraqi government began pursuing plans to construct a 65,000-seat soccer stadium in the port city of Basra, in southeastern Iraq. The proposal was highly ambitious for a country that has spent decades embroiled in wars and conflicts. The nation had not seen a public works project at anywhere near the scale of the stadium in many years, so its construction industry had neither the experience nor the supplies to complete the project alone. Instead, local contractors collaborated with architects, engineers, fabricators, and other contractors from across the region and around the world to see the project to fruition.
The Ministry of Youth and Sport, the government agency that oversees athletics in Iraq, decided to construct the stadium as the centerpiece of a new athletics campus known as Basra Sports City. The campus will eventually also include velodromes, basketball arenas, and indoor aquatics centers, making it one of the largest sports complexes in the Middle East. The ministry held a design/build competition and selected a team comprising Abdullah Al-Jiburi, a construction firm based in Baghdad, Iraq, and American firms 360 Architecture, headquartered in Kansas City, Missouri, and Thornton Tomasetti, Inc., an engineering firm headquartered in New York City, to design and construct the primary stadium—which doubles as an international track and field arena—and a 10,000-seat secondary stadium. The schedule for the project was ambitious, the goal being to complete the primary stadium in time to host the 2013 Gulf Cup of Nations, a soccer tournament that is traditionally held every two years in a different Arab city.
The Iraqi government had two primary requests for the stadium's design: it had to be among the largest in the region, and its architecture had to be reflective of Iraq. To that end, 360 Architecture, which also developed the master plan for the complex, drew inspiration for the stadium's design from the undulating bark of the date palm trees that are common across Iraq and the texture of the nation's traditional woven goods. As a result, the architects wrapped the stadium in a facade of interwoven glass fiber-reinforced polymer (GFRP) panels, giving the oval-shaped structure a basket-like appearance. "The Iraqi government wanted an architectural showcase that represented the history of Iraq," explains Steven Hofmeister, P.E., S.E., LEED-AP, M.ASCE, a senior principal of Thornton Tomasetti. "They did not want an international piece of architecture dropped there that wasn't relevant to the country."
The 65,000-seat soccer stadium is the cornerstone of a new sports complex in Basra, Iraq. Courtesy of 360 Architecture, Inc.
But achieving the facade presented many challenges, the first being the geometry of the GFRP panels. The initial design called for five different-sized panels for the stadium's sidelines and end zones. But because the stadium is oval and has two different degrees of curvature, the initial design would have required the panel fabricator, BFG International, a composite materials manufacturer headquartered in Manama, Bahrain, to make 10 different molds—five for the sideline panels and five more for the end zone panels, says Jonatan Schumacher, the director of advanced computational modeling at Thornton Tomasetti. It takes roughly four and a half months to fabricate just one mold, so it would have taken approximately four years to make all 10 molds—much too long to meet the project's targeted completion date, Schumacher says. At that point, Thornton Tomasetti's computational modeling team joined the project to rationalize the geometry and develop a way to use the same mold for both the sidelines and end zones.
The modeling team used a software package known as Digital Project—a product developed by Gehry Technologies, a Los Angeles-based architecture, engineering, and construction technology development and consulting firm founded by architect Frank Gehry. The software enabled the team to easily communicate with the panel fabricator and the architect as it manipulated the panel geometry. Following a great deal of back and forth with the other project team members, the modeling team achieved its goal of developing a geometry that allowed it to use the same five molds to make both the sideline and end zone panels. "The trick in the end was that we developed this geometry that allowed us to essentially just trim the molds," Schumacher says. "The sideline panels are about two feet shorter than the end zone panels, so we could make them from the same mold if we just trimmed them down."
A man-made lake in the shape of Iraq was formed around the stadium following construction. Courtesy of 360 Architecture, Inc.
After developing the new panel geometry, the team faced yet another challenge. The panels had to be trucked from the fabrication site in Bahrain through Saudi Arabia and Kuwait before finally arriving at the construction site in Basra. But the largest trailer that was permitted to drive through all of the countries was too small to carry the largest panels. As a result, the modeling team had to modify the geometry again, increasing the size of the smallest panels while reducing that of the largest panels in order to still use the same five molds for all of the panels. "We have a parametric model, so luckily we didn't have to redesign everything from scratch," Schumacher says. "We just changed some of the parameters, like the height and the width, of the panels." The end zone panels are approximately 30 m long from end to end, while the sideline panels are slightly shorter. All of the panels range from approximately 6 m to 3.5 m wide.
The modeling team also designed the brackets that connect the panels to the stadium's steel perimeter columns, which incline up to 14 degrees. Located at either end and at the center of each panel, the brackets have 4 degrees of freedom in order to allow the panels to slide back and forth as a result of thermal expansion and to accommodate construction tolerances. "If the columns were not installed exactly as modeled, if they were out of angle by half of a degree or something, then all they had to do was simply move the bracket back or forward a bit to meet the panel," Schumacher says. The modeling team began the modeling and bracket design process in May 2010 and submitted the final geometry to the panel fabricator that July. The team then helped determine the placement of the steel shrouds that cover the stadium's perimeter columns. Zahner Sheet Metal, an engineering and fabrication firm headquartered in Kansas City, Missouri, manufactured the shrouds using pretreated A588 weathering steel. Featuring a traditional Arabic pattern, the shrouds were thin enough to be shipped flat and then curved at the construction site to wrap around the columns.
The stadium’s roof cantilevers 46 m from the perimeter columns over the seating bowl. Courtesy of 360 Architecture, Inc.
Foundation construction began in late 2009, well before the rest of the stadium's design was completed. The team used infill to raise the site approximately 3 m, but the soil conditions remained poor. As a result, the stadium—framed in cast-in-place concrete with precast seating arranged within a lower and upper seating bowl—was founded on 800 mm diameter piles that descend to a depth of approximately 24 m. The site also has a high water table and contains a great deal of sulfur and chloride, both of which can significantly deteriorate concrete. To protect the structure, corrosion-resistant concrete mixtures were developed, and waterproofing slabs and pile caps were incorporated into the design. A contractor from Turkey carried out the foundation work. "There was a lot of money spent at the foundation level that would not have been spent had this been at a higher, drier location," Hofmeister says. A man-made lake shaped like Iraq was formed around the stadium following construction.
The stadium is partially covered by a roof that cantilevers 46 m from the perimeter columns over the seating bowl, an 18 m long back span capping the upper-level concourse. The roof is framed in hollow circular sections, which were welded in a shop and then bolted together at the site to form triangular trusses before being lifted into place. A glass band up to 4.5 m wide at the inner edge of the roof allows sunlight to stream into the stadium. "The shape of the glass on the roof varies as you go around the stadium," Hofmeister says. "That was determined by sunsets and by how much glass we needed to [be able to] provide sunlight onto the field to allow the grass to grow."
Although the goal was to complete the stadium in time for the Gulf Cup of Nations in January 2013, the challenges associated with building in a nation that has been ravaged by war and coordinating expertise and materials around the globe delayed construction. As a result, the stadium opened several months later than initially anticipated, in October. Still, the project represents a significant step forward for reconstruction in Iraq. "This is the first large public structure that had been built in Iraq in many years, so the local craftsman didn't have experience working at this scale. But once they were given the opportunity to get the experience, they performed very well," Hofmeister says. He adds that "this project demonstrates how far the Iraqi construction community has advanced after the war and [illustrates] their ability to create a world-class stadium."