The Chicago Spire is a supertall skyscraper under construction in Chicago, Illinois. The Spire will surpass Chicago's own Sears Tower, currently at 442 m (1,450 feet) tall, and New York's upcoming Freedom Tower, planned to be 541 m (1,776 feet) tall, to become North America's tallest tower.The current design also will surpass the height of the CN Tower in Toronto to become North America's tallest free-standing structure. The Chicago Spire would also surpass the Q1 in Queensland, the Eureka Tower in Melbourne, and the Princess Tower in Dubai, United Arab Emirates, to become the world's tallest all-residential building. Other world records, though, will by that year likely rest with the Burj Dubai, currently under construction in Dubai, United Arab Emirates.The building was designed by Spanish architect Santiago Calatrava and is being developed by Garrett Kelleher of Shelbourne Development Group, Inc. The Chicago Spire is scheduled to be completed in 2011 with 150 floors.
Crane parts and construction equipment arrived at the site on June 25, 2007. In preparation for construction, 34 concrete and steel caissons will be drilled 120 feet (37 m) into bedrock underlying the Earth's surface.A cofferdam with a 104 foot (31 m) diameter and 78 foot (24 m) depth will be installed to create a work environment and will later act as a foundation for the building's core. The underground portion of the construction is expected to be completed in the first quarter of 2008.
Originally proposed as "Fordham Spire" in July of 2005, the design called for 115 stories. The building was planned to include a hotel and condominiums and also featured a tall broadcast antenna mast. However the original Chicago developer Christopher T. Carley of the Fordham Company ran into financial problems. As a result, the project was taken over by the Irish developer Garrett Kelleher who changed the design to make the building solely residential and removed the above-ground parking lot, incorporating underground parking into the spire itself.
The skyscraper is being constructed along Chicago's lake front west of Navy Pier, located northeast of Chicago's Loop, in the Streeterville neighborhood of the Near North Side community area. The construction site is at the junction of Lake Michigan and the Chicago River. The site is bordered by the Ogden Slip of the Chicago River to the north, North Lake Shore Drive to the east, the Chicago River to the south, and existing residential property to the west. The site was originally zoned for two 35- to 50-story buildings.
Chicago's buildings are known for innovative designs. The Chicago Spire aims to complement this pattern, and standing at 2,000 feet (610 m), will further transform the already changing Chicago skyline. Plans for the tower include 1,193 condominiums with each of the building's 150 stories rotating exactly 2.44 degrees from the one below for a total 360 degree rotation. For supplemental structural support, each floor would be surrounded by cantilevered corners and four concave sides.
Similar to the Sears Tower and John Hancock Center skydecks, the Chicago Spire will house a community room at the top floor offering residents a view of four states. The soaring four story lobby of the skyscraper will have translucent glass walls and be framed by arching, steel reinforced concrete vaults.The building has been labeled as a giant "drill bit" by the public and others in the media have likened it to a "tall twisting tree" and a "blade of grass".
The curved design, may provide two major benefits to the structure of the building. First, curved designs have a tendency of adding to the strength of a structure. A similar principle has been applied in the past when building curved stadium roofs.
In addition to structural support, the curved face of the exterior will minimize wind forces. In rectangular buildings, a fluid wind flow puts pressure on the windward face of the building, while as air moves around it, a suction is applied to the leeward face. This often causes a sway in tall buildings which can be counteracted, at least partially, by stiffening the structure or by using a dynamic wind damper. Although the curved design of the Chicago Spire will not completely negate wind forces, a tapering concrete core and twelve shear walls emanating from it are installed to counteract these forces instead.
Additionally, the Chicago Spire will incorporate world-class sustainable engineering practices to meet the Gold standard of Leadership in Energy and Environmental Design certification. Sustainable features include recycled rainwater, river water used for cooling, ornithologically-sensitive glass to protect migratory birds, intelligent building and management systems, waste storage and recycling management, and a monitored outdoor air delivery.
(Information comes courtesy of the Wikipedia amongst other sources.)