Jay Pritzker Pavilion - Construction

Construction

Jay Pritzker Pavilion cost $60 million, a quarter of which came from the Pritzker family donation. It includes 4,000 fixed seats and a 95,000-square-foot (8,800 m2) Great Lawn that can accommodate an additional 7,000 people. The pavilion was built above and behind the Harris Theater, which has the benefit that Millennium Park's indoor and outdoor performance venues share a loading dock, rehearsal rooms and other backstage facilities.

The bandshell's brushed stainless steel headdress frames the 120-foot (37 m) proscenium theatre; the main stage can accommodate a full orchestra and chorus of 150 members. The bandshell is connected to a trellis of interlocking crisscrossing steel pipes that support the innovative sound system, which mimics indoor concert hall acoustics. The pavilion has restrooms on both its east and west sides. It is one of two features in the park to include accessible restrooms; the other is McCormick Tribune Plaza & Ice Rink. The majority of the park's 123 toilet fixtures (78 for women, 45 for men) are located in underground arcades to the east and west of the pavilion, with the ones on the east being heated for winter use.

Millennium Park is built on top of a large underground parking garage. Construction started before the park's design was completed, and in January 2000, 17 additional caissons had to be added to the partially built garage to support the weight of Gehry's pavilion. In April the tops of all these caissons had to be rebuilt for changes in the pavilion's foundation.

U.S. Equities Realty was responsible for negotiating contracts with Gehry and all contractors. Walsh Construction and its subcontractors were hired to execute three elements of Gehry's design: the structural steel supporting the stainless steel ribbons, the ribbons themselves and the trellis and associated sound system.

The LeJeune Steel Company of Minneapolis was the subcontractor for the structural steel. The pavilion's concrete walls frame the orchestra shell space, which is 100 feet (30 m) wide, 50 feet (15 m) tall and has no support columns. The pavilion's roof rests on a dozen north–south trusses supported by east–west truss girders. The south side of the orchestra shell space is enclosed by the glass doors of the proscenium, which are about 50 feet (15 m) tall, 100 feet (30 m) wide and function like aircraft hangar doors made of glass. They were the largest doors that Glass Solutions of Elmhurst, Illinois, ever produced; the thickness of the glass was a design problem for the steel supports.

Zahner of Kansas City, Missouri, was the subcontractor for the pavilion's ribbons, described as "stainless steel panels that appear to be peeling back from the central opening". The proscenium's metal ribbons are composed of 697 panels that range from 6 to 300 square feet (0.56–28 m2) and 1,600 to 20,000 pounds (730–9,100 kg) with a thickness of about 14 inches (36 cm). They are made from aluminum with a stainless steel outer layer that has a uniform shade across all panels. The structural steel for the ribbons had an abnormally low fit tolerance of 0.125 inches (3.2 mm), rather than the standard 1 to 2 inches (25 to 51 mm). The proscenium was inspired by Gehry's 2001 flagship store for Issey Miyake in New York City, which has sculptured titanium that represents pleating. During construction, about five cranes and 18 aerial lifts were on site. The apex of the center element is approximately 150 feet (46 m) high, which was near the limits of basic construction equipment at the time.

Acme Structural of Springfield, Missouri, was the subcontractor for the trellis over the Great Lawn, which resulted from the distributed sound system's requirement for speakers every 70 feet (21 m). One way to achieve this would have involved placing the speakers on pipes or columns, but the resulting forest of columns seemed discordant with the architecture. Gehry preferred the trellis although it cost about $3 million more than speakers arranged on posts would have. The trellis uses 22 criss-crossing arches in a lattice pattern, and is noted for its parabolic grid. The arches use pipes varying in diameter from 12–20 inches (30–51 cm) depending upon the load requirements. Arches longer than 300 feet (91 m) have four or five different radii, where radius describes the extent of pipe curvature. The arch pipes connect to the structural steel of the pavilion structure without linking to the metal ribbons. The trellis is 600 by 300 feet (180 by 91 m).

The pavilion's construction was aided by the French CATIA software program and internet conferencing. Early plans to incorporate a surrounding waterfall and stairway were abandoned. In the end, budget limitations led to compromises with the original architectural plan that left many elements in their most straightforward form, such as exposed pipes and conduits, or rough concrete.