The Citigroup Center is one of the largest skyscrapers in New York City, United States, located at 601 Lexington Avenue between 53rd Street and 54th Street in midtown Manhattan. The 59-floor, 915-foot (279 m) building is one of the most distinctive and imposing in New York's famous skyline, with a 45° angled top and a genuinely unique stilt-style base. It contains 1.3 million square feet (120,000 m²) of office space, and the 45-degree angle at the top of the building was originally intended to contain solar panels to provide energy (this idea was eventually dropped, however). It was designed by architect Hugh Stubbins Jr. for Citibank, and was completed in 1977. Taipei 101, the worlds tallest skyscraper by roof height on high rise. ... Nickname: Big Apple, City that never Sleeps, Gotham Location in the state of New York Coordinates: Country United States State New York Boroughs The Bronx Brooklyn Manhattan Queens Staten Island Settled 1613 Mayor Michael Bloomberg (R) Area    - City 1,214. ... Lexington Avenue is an avenue on the East Side of the borough of Manhattan in New York City that carries southbound one-way traffic from East 131st Street to Gramercy Park at East 21st Street. ... The Borough of Manhattan, highlighted in yellow, lies between the East River and the Hudson River. ... A stiltwalker participates in a parade dressed as a court jester Stilts are poles, posts or pillars used to allow a person or structure to stand at a certain distance above the ground. ... A photovoltaic (PV) module that is composed of multiple PV cells. ... Citigroup Center in New York Hugh Asher Stubbins Jr. ... Citibank was founded in 1812 as the City Bank of New York. ... For the album by Ash, see 1977 (album). ...

Nickname: Big Apple, City that never Sleeps, Gotham Location in the state of New York Coordinates: Country United States State New York Boroughs The Bronx Brooklyn Manhattan Queens Staten Island Settled 1613 Mayor Michael Bloomberg (R) Area    - City 1,214. ... Architect at his drawing board, 1893 An Ciara Danille Bowers is a person who is involved in the planning, designing and oversight of a buildings construction. ... Emery Roth (1871 – August 20, 1948) was an American architect who built many of the definitive New York City hotels and apartment buildings of the 1920s and 30s, incorporating Beaux-Arts and Art Deco details. ...

History

The site was originally occupied by St. Peter's Evangelical Lutheran Church which was founded in 1862. In 1905 the church moved to the location of 54th street and Lexington Avenue. 1862 was a common year starting on Wednesday (see link for calendar). ...

Early engineering details

From the very beginning, the Citigroup Center was an engineering challenge. When planning for the skyscraper began in the early 1970s, the northwest corner of the proposed building site was occupied by St. Peter's Lutheran Church. The church allowed Citicorp to build the skyscraper under one condition: a new church would have to be built on the same corner, with no connection to the Citicorp building and no columns passing through it, because the church wanted to remain on the site of the new development, near one of the intersections. Architects wondered at the time if this demand was too much, and if the proposal could even work. Deconstructing a Roman pillar. ...

Structural engineer William LeMessurier set the 59-story tower on four massive 114 foot (35 m) high columns, positioned at the center of each side, rather than at the corners. This design allowed the northwest corner of the building to cantilever 72 feet (22 m) over the new church. To accomplish these goals LeMessurier designed a system of stacked load bearing braces, in the form of inverted chevrons. Each chevron would redirect the massive loads to their center, then downward into the ground through the uniquely-positioned columns. The engineer responsible for the structural desing of the Citicorp headquarters tower, in New York, (1977). ... The cantilevered beam (green) projects out into space from its supports (blue). ...

The building's engineering crisis of 1978

Changes during construction led to a finished product that was structurally unsound. In 1978, prompted by a question from a student, LeMessurier discovered a potentially fatal flaw in the building's construction: the skyscraper's bolted joints were too weak to withstand 70-mile-per-hour (113 km/h) wind gusts at specific angles. 1978 (MCMLXXVIII) was a common year starting on Sunday. ...

While LeMessurier's original design and load calculations for the special, uniquely-designed 'chevron' load braces used to support the building were based on welded joints, a labor and cost-saving change altered the joints to bolted construction after the building's plans were approved.

The engineers did not recalculate what the construction change would do to the wind forces acting on two surfaces of the building's curtain wall at the same time; if hurricane-speed winds hit the building at a 45-degree angle there was the potential for catastrophic failure due to bolt failure. The wind speeds needed to topple the models of Citigroup Center in a wind-tunnel test were predicted to occur in New York City every 16 years. Image File history File linksMetadata Download high-resolution version (2848x2136, 2974 KB) Citigroup Center. ... Image File history File linksMetadata Download high-resolution version (2848x2136, 2974 KB) Citigroup Center. ... Glass curtain wall of the Bauhaus Dessau. ... NASA wind tunnel with the model of a plane A wind tunnel is a research tool developed to assist with studying the effects of air moving over or around solid objects. ...

LeMessurier reportedly agonised over how to deal with the problem - making it known to the wider world risked ruining his professional reputation. But with hurricane season fast approaching, he took the bold decision to approach Citicorp directly, and advise them of the need to take swift remedial action. He convinced Citicorp to hire a crew of welders to repair the fragile building without informing the public, a task made easier by the press strike at that time. Hurricane seaons can refer to : The Atlantic hurricane season The Pacific hurricane season This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ...

For the next three months, a construction crew welded two-inch-thick steel plates over each of the skyscraper's 200 bolted joints during the night, after each work day, almost unknown to the general public. Six weeks into the work, a major storm, Hurricane Ella (1978 Atlantic hurricane season), was off Cape Hatteras and heading for New York. With only half the reinforcement finished, New York City was hours away from emergency evacuation. Luckily, Ella turned eastward and veered out to sea, buying enough time for workers to permanently correct the problem. The 1978 Atlantic hurricane season was an ongoing event in the annual cycle of tropical cyclone formation. ... An aerial view of the Cape Hatteras Lighthouse (before its relocation in 1999) Cape Hatteras from space, October 1989 Cape Hatteras is a cape on the coast of North Carolina. ...

Despite the fact that nothing actually happened as a result of the engineering gaffe, the crisis was kept hidden from the public for almost 20 years. LeMessurier's act of alerting Citicorp to the problem inherent in his own design is now used as a textbook example of ethical behavior.

After the modifications of the bolted members were completed, the building is now generally considered to be one of the most structurally sound skyscrapers in the world.

Other notable features

Citygroup Center is bigger than a tv.

• To help stabilize the building, a tuned mass damper was placed in the mechanical space at its top. This substantial piece of stabilizing equipment weighs 400 tons and has a volume of 255 cubic feet (7 m³). Designed to counterbalance the effects of wind by making the building sway, it is a concrete block that slides on a thick layer of oil and converts the kinetic energy of the building into friction. This mass reduces the building's movement from wind deflection by 50%. Citigroup Center was the first skyscraper in the United States to feature a tuned mass damper.

• The building features double-deck elevators, which are separated to serve only odd or even floors.

• It is one of the tallest buildings in New York City.

• The Citigroup Centre was built on the site of 53rd and 3rd street - which was immortalised in a song by punk rock band The Ramones. It was released February 1976. The song, written by Dee Dee Ramone, refers to a famous spot for male prostitution in New York where it is speculated that he himself had been a "hustler"; and used the money earned there to pay for his heroin habit which he immortalized in "Chinese Rock", and which ultimately killed him (he died from an overdose in 2002).

Image File history File linksMetadata Download high-resolution version (2848x2136, 2947 KB) Citigroup Center in Manhattan. ... Image File history File linksMetadata Download high-resolution version (2848x2136, 2947 KB) Citigroup Center in Manhattan. ... A tuned mass damper is a device mounted in structures to prevent discomfort, damage or outright structural failure by vibration. ... Double-deck elevators are elevators designed such that two elevator cars are attached one on top of the other. ... New York City has the most skyscrapers in the world with 50 buildings taller than 200 meters and 2 taller than 300 meters. ... The Ramones (L-R, Johnny, Tommy, Joey, Dee Dee) on the cover of their debut self-titled album (1976), cementing their place at the dawn of the punk movement. ... Dee Dee Ramone, 1979 Dee Dee Ramone (Douglas Glenn Colvin) (September 18, 1952 - June 5, 2002) was an American songwriter and bassist, best remembered as a founding member of punk rock band the Ramones. ...

References

• Horsley, Carter B. The Midtown Book. Found at The City Review.
• PBS's "Building Big" Series
• A Potentially Disastrous Design Error

External Links

• Emporis Skyscrapers Factfile

• Maps and aerial photos Coordinates: 40.758533° -73.970314°
  • Satellite image from WikiMapia, Google Maps or Windows Live Local
  • Street map from MapQuest or Google Maps
  • Topographic map from TopoZone
  • Aerial image from TerraServer-USA