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Burj Khalifa
Burj Khalifa ( "Khalifa Tower"), known as Burj Dubai prior to its inauguration, is a skyscraper in Dubai, United Arab Emirates, and the tallest man-made structure ever built, at . Construction began on 21 September 2004, with the exterior of the structure completed on 1 October 2009. The building officially opened on 4 January 2010, and is part of the new flagship development called Downtown Dubai at the 'First Interchange' along Sheikh Zayed Road, near Dubai's main business district. The tower's architecture and engineering were performed by Skidmore, Owings, and Merrill of Chicago, with Adrian Smith (now at his own firm) as chief architect, and Bill Baker as chief structural engineer. The primary contractor was Samsung C&T of South Korea. In June 2010, Burj Khalifa was the recipient of the 2010 Best Tall Building Middle East & Africa award by the Council on Tall Buildings and Urban Habitat. The total cost for the project was about US$1.5 billion; and for the entire 'Downtown Dubai', US$20 billion. In March 2009, Mohamed Ali Alabbar, Chairman of the project's developer, Emaar Properties, said office space pricing at Burj Khalifa reached US$4,000 per sq ft (over US$43,000 per m2) and the Armani Residences, also in Burj Khalifa, sold for US$3,500 per sq ft (over US$37,500 per m2). The project's completion coincided with the global financial crisis of 2007–2010, and with vast overbuilding in the country, led to high vacancies and foreclosures. With Dubai mired in debt from its huge ambitions, the government was forced to seek multi-billion dollar bailouts from its oil-rich neighbor Abu Dhabi. Subsequently, in a surprise move at its opening ceremony, the tower was renamed Burj Khalifa, said to honor the UAE President, Khalifa bin Zayed Al Nahyan for his crucial support. ConceptionBurj Khalifa has been designed to be the centrepiece of a large-scale, mixed-use development that will include 30,000 homes, nine hotels such as The Address Downtown Dubai, of parkland, at least 19 residential towers, the Dubai Mall, and the man-made Burj Khalifa Lake.The building has returned the location of Earth's tallest free-standing structure to the Middle Eastwhere the Great Pyramid of Giza claimed this achievement for almost four millennia before being surpassed in 1311 by Lincoln Cathedral in England. The decision to build Burj Khalifa is reportedly based on the government's decision to diversify from an oil-based economy to one that is service- and tourism-oriented. According to officials, it is necessary for projects like Burj Khalifa to be built in the city to garner more international recognition, and hence investment. "He (Sheikh Mohammed bin Rashid Al Maktoum) wanted to put Dubai on the map with something really sensational," said Jacqui Josephson, a tourism and VIP delegations executive at Nakheel Properties. HeightCurrent records
History of height increasesthumb|Burj Khalifa compared to some other well-known tall structuresThere are unconfirmed reports of several planned height increases since its inception. Originally proposed as a virtual clone of the Grollo Tower proposal for Melbourne, Australia's Docklands waterfront development, the tower was redesigned with an original design by Skidmore, Owings and Merrill (SOM) discussed below. Marshall Strabala, an SOM architect who worked on the project until 2006, late 2008 said that Burj Khalifa was designed to be tall. The design architect, Adrian Smith, felt that the uppermost section of the building did not culminate elegantly with the rest of the structure, so he sought and received approval to increase it to the current height. It has been explicitly stated that this change did not include any added floors, which is fitting with Smith's attempts to make the crown more slender. DelayEmaar Properties announced on 9 June 2008 that construction of Burj Khalifa was delayed by upgraded finishes and would be completed only in September 2009. An Emaar spokesperson said "The luxury finishes that were decided on in 2004, when the tower was initially conceptualized, is now being replaced by upgraded finishes. The design of the apartments has also been enhanced to make them more aesthetically attractive and functionally superior." A revised completion date of 2 December 2009 was then announced. However, Burj Khalifa was opened on 4 January 2010.Architecture and designthumb|right|Cross-section comparisonsright|thumb|A Hymenocallis flower showing six spokes, as pattern for the three-lobed designThe tower is designed by Skidmore, Owings and Merrill, which also designed the Willis Tower (formerly the Sears Tower) in Chicago, Illinois and 1 World Trade Center in New York City, among numerous other famous high-rises. The building resembles the bundled tube form of the Willis Tower, but is not a bundle tube structure. Its design is reminiscent of Frank Lloyd Wright's vision for The Illinois, a mile-high skyscraper designed for Chicago. According to Marshall Strabala, an SOM architect who worked on the building's design team, Burj Khalifa was designed based on the 73-floor Tower Palace Three, an all-residential building in Seoul, South Korea. In its early planning, Burj Khalifa was intended to be entirely residential. Subsequent to the original design by Skidmore, Owings and Merrill, Emaar Properties chose Hyder Consulting to be the supervising engineer. Hyder was selected for its expertise in structural and MEP (mechanical, electrical and plumbing) engineering. Hyder Consulting's role was to supervise construction, certify SOM's design, and be the engineer and architect of record to the UAE authorities. Emaar Properties also engaged GHD, an international multidisciplinary consulting firm, to act as an independent verification and testing authority for concrete and steelwork. The design of Burj Khalifa is derived from patterning systems embodied in Islamic architecture. According to the structural engineer, Bill Baker of SOM, the building's design incorporates cultural and historical elements particular to the region. The Y-shaped plan is ideal for residential and hotel usage, with the wings allowing maximum outward views and inward natural light. The design architect, Adrian Smith, has said the triple-lobed footprint of the building was inspired by the flower Hymenocallis. The tower is composed of three elements arranged around a central core. As the tower rises from the flat desert base, setbacks occur at each element in an upward spiralling pattern, decreasing the cross section of the tower as it reaches toward the sky. There are 27 terraces in Burj Khalifa. At the top, the central core emerges and is sculpted to form a finishing spire. A Y-shaped floor plan maximizes views of the Persian Gulf. Viewed from above or from the base, the form also evokes the onion domes of Islamic architecture. During the design process, engineers rotated the building 120 degrees from its original layout to reduce stress from prevailing winds. At its tallest point, the tower sways a total of . To support the unprecedented height of the building, the engineers developed a new structural system called the buttressed core, which consists of a hexagonal core reinforced by three buttresses that form the ‘Y' shape. This structural system enables the building to support itself laterally and keeps it from twisting. The spire of Burj Khalifa is composed of more than of structural steel. The central pinnacle pipe weighing was constructed from inside the building and jacked to its full height of over using a strand jack system. The spire also houses communications equipment. More than 1,000 pieces of art will adorn the interiors of Burj Khalifa, while the residential lobby of Burj Khalifa will display the work of Jaume Plensa, featuring 196 bronze and brass alloy cymbals representing the 196 countries of the world. The visitors in this lobby will be able to hear a distinct timbre as the cymbals, plated with 18-carat gold, are struck by dripping water, intended to mimic the sound of water falling on leaves. The exterior cladding of Burj Khalifa consists of of reflective glazing, and aluminium and textured stainless steel spandrel panels with vertical tubular fins. The cladding system is designed to withstand Dubai's extreme summer temperatures. Additionally, the exterior temperature at the top of the building is thought to be 6°C (11°F) cooler than at its base. Over 26,000 glass panels were used in the exterior cladding of Burj Khalifa. Over 300 cladding specialists from China were brought in for the cladding work on the tower. An Armani Hotel, the first of four by Armani, occupies 15 of the lower 39 floors. The hotel was supposed to open on 18 March 2010 but after several delays the hotel finally opened the public on 27 April 2010. The corporate suites and offices were also supposed to open from March onwards but the hotel and observation deck remain the only parts of the building which are open. The sky lobbies on the 43rd and 76th floors will house swimming pools. Floors through to 108 will have 900 private residential apartments (which, according to the developer, sold out within eight hours of being on the market). An outdoor zero-entry swimming pool will be located on the 76th floor of the tower. Corporate offices and suites fill most of the remaining floors, except for a 122nd, 123rd and 124th floor where the At.mosphere restaurant, sky lobby and an indoor and outdoor observation deck is located respectively. Burj Khalifa will receive its first residents from February 2010. They will be among the first of 25,000 people who will live there. Burj Khalifa is expected to hold up to 35,000 people at any one time. A total of 57 elevators and 8 escalators are installed. The elevators have a capacity of 12 to 14 people per cabin, the fastest rising and descending at up to . Engineers had considered installing the world's first triple-deck elevators, but the final design calls for double-deck elevators. The double-deck elevators are equipped with entertainment features such as LCD displays to serve visitors during their travel to the observation deck. The building has 2,909 stairs from the ground floor to the 160th floor. The graphic design identity work for Burj Khalifa is the responsibility of Brash Brands, who are based in Dubai. Design of the global launch events, communications, and visitors centers for Burj Khalifa have also been created by Brash Brands as well as the roadshow exhibition for the Armani Residences, which are part of the Armani Hotel within Burj Khalifa, which toured Milan, London, Jeddah, Moscow and Delhi. Water supply systemThe Burj Khalifa's water system supplies an average of of water per day.At the peak cooling times, the tower requires cooling equivalent to that provided by of melting ice in one day. The building has a condensate collection system, which uses the hot and humid outside air, combined with the cooling requirements of the building and results in a significant amount of condensation of moisture from the air. The condensed water is collected and drained into a holding tank located in the basement car park, this water is then pumped into the site irrigation system for use on the Burj Khalifa park. MaintenanceTo wash the 24,348 windows, a horizontal track has been installed on the exterior of Burj Khalifa at levels 40, 73 and 109. Each track holds a bucket machine which moves horizontally and then vertically using heavy cables. Above level 109, up to tier 27 traditional cradles from davits are used. The top of the spire, however, is reserved for specialist window cleaners, who brave the heights and high winds dangling by ropes to clean and inspect the top of the pinnacle. Under normal conditions, when all building maintenance units will be operational, it will take 36 workers three to four months to clean the entire exterior facade.Unmanned machines will clean the top 27 additional tiers and the glass spire. The cleaning system was developed in Australia at a cost of A$8 million. FeaturesThe Dubai Fountainthumb|right|The Dubai FountainOutside, and at a cost of Dh 800 million (US$217 million), a record-setting fountain system was designed by WET Design, the California-based company responsible for the fountains at the Bellagio Hotel Lake in Las Vegas. Illuminated by 6,600 lights and 50 coloured projectors, it is long and shoots water into the air, accompanied by a range of classical to contemporary Arabic and world music. On 26 October 2008 Emaar announced that based on results of a naming contest the fountain would be called the Dubai Fountain. Observation deckAn outdoor observation deck, named At the Top, opened on 5 January 2010 on the 124th floor. It is the third highest observation deck in the world and the highest outdoor observation deck in the world, at . To manage the daily rush of sightseers, Emaar Properties offers advance purchase tickets for a specific date and time at a 75% discount over tickets purchased on the spotOn 8 February 2010, the observation deck was closed to the public after power supply problems caused an elevator to become stuck between floors, trapping a group of tourists for 45 minutes. Despite rumours of the observation deck reopening for St. Valentines Day (14 February), it remained closed until 4 April 2010. Burj Khalifa parkBurj Khalifa is surrounded by an park designed by landscape architects SWA Group. The design of the park is also inspired by the core design concepts of Burj Khalifa which is based on the symmetries of the desert flower, Hymenocallis. The park has six water features, gardens, palm lined walkways, and flowering trees. At the centre of the park and the base of Burj Khalifa is the water room, which is a series of pools and water jet fountains. In addition the railing, benches and signs incorporate images of Burj Khalifa and the Hymenocallis flower.The plants and the shrubbery will be watered by the buildings's condensation collection system,that uses water from the cooling system. The system will provide annually. WET designers, who also developed the Dubai Fountain, developed the park's six water features. Floor plansThe following is a breakdown of floors.Constructionright|thumb|Animation of construction processthumb|upright|Aerial closeup of Burj Khalifa under construction in March 2008The tower was constructed by South Korean company, Samsung Engineering & Construction, which also did work on the Petronas Twin Towers and Taipei 101. Samsung Engineering & Construction built the tower in a joint venture with Besix from Belgium and Arabtec from UAE. Turner is the Project Manager on the main construction contract. Under UAE law, the Contractor and the Engineer of Record, Hyder Consulting, is jointly and severally liable for the performance of Burj Khalifa. The primary structural system of Burj Khalifa is reinforced concrete. Over of concrete, weighing more than were used to construct the concrete and steel foundation, which features 192 piles, with each pile is 1.5 metre diameter x 43 metre long buried more than deep. Burj Khalifa's construction used of concrete and 55,000 tonnes of steel rebar, and construction took 22 million man-hours. A high density, low permeability concrete was used in the foundations of Burj Khalifa. A cathodic protection system under the mat is used to minimize any detrimental effects from corrosive chemicals in local ground water. The previous record for pumping concrete on any project was set during the extension of the Riva del Garda Hydroelectric Power Plant in Italy in 1994, when concrete was pumped to a height of . Burj Khalifa exceeded this height on 19 August 2007, and as of May 2008 concrete was pumped to a delivery height of , the 156th floor. The remaining structure above is built of lighter steel. Burj Khalifa is highly compartmentalised. Pressurized, air-conditioned refuge floors are located approximately every 35 floors where people can shelter on their long walk down to safety in case of an emergency or fire. Special mixes of concrete are made to withstand the extreme pressures of the massive building weight; as is typical with reinforced concrete construction, each batch of concrete used was tested to ensure it could withstand certain pressures. The consistency of the concrete used in the project was essential. It was difficult to create a concrete that could withstand both the thousands of tonnes bearing down on it and Persian Gulf temperatures that can reach . To combat this problem, the concrete was not poured during the day. Instead, during the summer months ice was added to the mixture and it was poured at night when the air is cooler and the humidity is higher. A cooler concrete mixture cures evenly throughout and is therefore less likely to set too quickly and crack. Any significant cracks could have put the entire project in jeopardy. The unique design and engineering challenges of building Burj Khalifa have been featured in a number of television documentaries, including the Big, Bigger, Biggest series on the National Geographic and Five channels, and the Mega Builders series on the Discovery Channel. Labour controversyBurj Khalifa was built primarily by workers from South Asia. Press reports indicated in 2006 that skilled carpenters at the site earned UK£4.34 a day, and labourers earned UK£2.84. According to a BBC investigation and a Human Rights Watch report, the workers were housed in abysmal conditions, their pay was often withheld, their passports were confiscated by their employers, and they were working in hazardous conditions that resulted in an apparently high number of deaths and injuries on site.On 21 March 2006, about 2,500 workers, who were upset over buses that were delayed for the end of their shifts, protested, damaging cars, offices, computers, and construction equipment. A Dubai Interior Ministry official said the rioters caused almost UK£500,000 in damage. Most of the workers involved in the riot returned the following day but refused to work. On 17 June 2008, there were 7,500 skilled workers employed in the construction of Burj Khalifa. Milestones
Official launch ceremonythumb|right|upright|The Burj Khalifa in its opening ceremonyThe opening of Burj Khalifa was held on 4 January 2010. The ceremony featured a display of 10,000 fireworks, light beams projected on and around the tower, and further sound, light and water effects. Using the 868 powerful stroboscope lights that are integrated into the facade and spire of the tower, different lighting sequences were choreographed, together with more than 50 different combinations of the other effects. The event began with a short film which depicted the story of Dubai and the evolution of Burj Khalifa. The displays of sound, light, water and fireworks followed. The portion of the show consisting of the various pyrotechnic, lighting, water and sound effects was divided into three. The first part was primarily a light and sound show, which took as its theme the link between desert flowers and the new tower, and was co-ordinated with the Dubai Fountain and pyrotechnics. The second portion, called 'Heart Beat', represented the construction of the tower in a dynamic light show with the help of 300 projectors which generated a shadow-like image of the tower. In the third act, sky tracers and space cannons enveloped the tower in a halo of white light, which expanded as the lighting rig on the spire activated. The ceremony was relayed live on a giant screen on Burj Park Island, as well as several television screens placed across the Downtown Dubai development. Hundreds of media outlets from around the world reported live from the scene. In addition to the media presence, 6,000 guests were expected. ReceptionBASE jumpingThe building has been used by several experienced BASE jumpers for both authorized and unauthorized BASE jumping:
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