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An Indian-born British artist Sir Anish Kapoor designed a beautiful sculpture that is now widely known as Cloud Gate, that is the centerpiece of AT&T Plaza at Millennium Park in the Loop community area of Chicago, Illinois. The sculpture and AT&T Plaza are located on top of Park Grill, between the Chase Promenade and McCormick Tribune Plaza & Ice Rink. Constructed between 2004 and 2006, the sculpture is nicknamed The Bean because of its shape. Kapoor's design was inspired by liquid mercury and the sculpture's surface reflects and distorts the city's skyline. Visitors are able to walk around and under Cloud Gate's 12-foot (3.7 m) high arch.
The sculpture builds upon many of Kapoor's artistic themes, and it is popular with tourists as a photo-taking opportunity for its unique reflective properties.
Design approved of Kapoor’s is measuring 33 by 66 by 42 feet (10 by 20 by 13 m) and weighing 110 short tons (100 t; 98 long tons), the proposal featured a seamless, stainless steel surface inspired by liquid mercury. This mirror-like surface would reflect the Chicago skyline, but its elliptical shape would distort and twist the reflected image. As visitors walk around the structure, its surface acts like a fun-house mirror as it distorts their reflections.
In the underside of the sculpture is the omphalos, an indentation whose mirrored surface provides multiple reflections of any subject situated beneath it. The apex of the omphalos is 27 feet (8.2 m) above the ground. The concave underside allows visitors to walk underneath to see the omphalos, and through its arch to the other side so that they view the entire structure. During the grand opening week in July 2004, press reports described the omphalos as the "spoon-like underbelly".
Issues During Design
Although Kapoor does not draw with computers, computer modeling was essential to the process of analyzing the complex form, which created numerous issues. Since the sculpture was expected to be outdoors, concerns arose that it might retain and conduct heat in a way that would make it too hot to touch during the summer and so cold that one's tongue might stick to it during the winter. The extreme temperature variation between seasons was also feared to weaken the structure. Graffiti, bird droppings and fingerprints were also potential problems, as they would affect the aesthetics of the surface. The most pressing issue was the need to create a single seamless exterior for the external shell, a feat architect Norman Foster once believed to be nearly impossible.
Kapoor officially named the piece Cloud Gate. Critical reviews describe the sculpture as a passage between realms. Three-quarters of the sculpture's external surface reflects the sky and the name refers to it acting as a type of gate that helps bridge the space between the sky and the viewer. The sculpture and plaza are sometimes referred to jointly as "Cloud Gate on the AT&T Plaza". It is Kapoor's first public outdoor work in the United States, and is the work by which he is best known in the country according to the Financial Times.
The British engineering firm Atelier One, and subsequently freelance engineer Chris Hornzee-Jones (who later went on to form the engineering firm Aerotrope in 2005) with Christopher Cieslak provided the sculpture's structural design, and Performance Structures, Inc. (PSI) was chosen to fabricate it because of their ability to produce nearly invisible welds. The project began with PSI attempting to recreate the design in miniature. A high-density polyurethane foam model was selected by Kapoor, which was then used to design the final structure, including the interior structural components. Initially, PSI planned to build and assemble the sculpture in Oakland, California, and ship it to Chicago through the Panama Canal and St. Lawrence Seaway. However, this plan was discarded after park officials deemed it too risky, so the decision was made to transport the individual panels by truck and to assemble the structure on-site, a task undertaken by MTH Industries.
The sculpture's weight raised concerns. Estimating the thickness of the steel needed to create the sculpture's desired aesthetics before fabrication was difficult. Cloud Gate was originally estimated to weigh 60 short tons (54 t; 54 long tons) when completed. However, the final figure was almost twice as heavy at 110 short tons (100 t; 98 long tons). This extra weight required engineers to reconsider the sculpture's supporting structures. The roof of the Park Grill, upon which Cloud Gate sits, had to be built strong enough to bear the weight. The large retaining wall separating Chicago's Metra train tracks from the North Grant Park garage supports much of the weight of the sculpture and forms the back side of the restaurant. This wall, along with the rest of the garage's foundation, required additional bracing before the piece was erected. Cloud Gate is further buttressed by lateral members underneath the plaza that are anchored to the sculpture's interior structure by tie rods.
Inside Cloud Gate's polished exterior shell are several steel structures that keep the sculpture standing. The first structural pieces, two type 304 stainless steel rings, were put into place in February 2004. As construction continued, crisscrossing pipe trusses were assembled between the two rings. The trusses and supporting structures were only present for the construction phases. The finished sculpture has no inner bracing. The supporting structural components were designed and constructed to ensure that no specific point was overloaded, and to avoid producing unwanted indentations on the exterior shell. The frame was also designed to expand and contract with the sculpture as temperatures fluctuate. As a result, the two large rings supporting the sculpture move independently of each other, allowing the shell to move independently of the rings.
When Cloud Gate's interior components were completed, construction crews prepared to work on the outer shell; this comprises 168 stainless steel panels, each 3⁄8 inch (10 mm) thick and weighing 1,000 to 2,000 pounds (450 to 910 kg). They were fabricated using three-dimensional modeling software. Computers and robots were essential in the bending and shaping of the plates, which was performed by English wheel and a robotic scanning device. Metal stiffeners were welded to each panel's interior face to provide a small degree of rigidity. About a third of the plates, along with the entire interior structure, were fabricated in Oakland. The plates were polished to 98 percent of their final state and covered with protective white film before being sent to Chicago via trucks. Once in Chicago, the plates were welded together on-site, creating 2,442 linear feet (744 m) of welded seams. Welders used keyhole welding machines rather than traditional welding guns. The plates were fabricated so precisely that no on-site cutting or filing was necessary when lifting and fitting them into position.
Chicago Mayor Richard M. Daley declared the day of the sculpture's dedication, May 15, 2006, to be "Cloud Gate Day". Kapoor attended the celebration, while local jazz trumpeter and bandleader Orbert Davis and the Chicago Jazz Philharmonic played "Fanfare for Cloud Gate", which Davis composed. The public took an instant liking to the sculpture, affectionately referring to it as "The Bean".
Cloud Gate has become a popular piece of public art and is now a fixture on many souvenirs such as postcards, sweatshirts, and posters. The sculpture has attracted a large number of locals, tourists, and art aficionados from around the world. The sculpture is now the piece by which Kapoor is most identified in the United States.
