Burj Khalifa (Arabic: برج خليفة "Khalifa Tower"),formerly known as Burj Dubai, is a skyscraper in Dubai, United Arab Emirates, and the tallest man-made structure ever built, at 828 m (2,717 ft). 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.The building is part of the 2 km2 (490-acre) flagship development called Downtown Burj Khalifa at the "First Interchange" along Sheikh Zayed Road, near Dubai's main business district.The tower's architecture and engineering was performed by Skidmore, Owings, and Merrill of Chicago. Adrian Smith, who worked with Skidmore, Owings and Merrill until 2006, was the chief architect and Bill Baker was the chief structural engineer for the project. The primary contractor was Samsung C&T of South Korea, who also built the Taipei 101 and Petronas Twin Towers. Major subcontractors included Belgian group Besix and Arabtec from the UAE. Turner Construction Company was chosen as the construction project manager. Under UAE law, the Contractor and the Engineer of Record are jointly and severally liable for the performance of Burj Khalifa. Therefore, by adoption of SOM's design and by being appointed as Architect and Engineer of Record, Hyder Consulting was legally the Design Consultant for the tower.
The total cost for the Burj Khalifa project was about US$1.5 billion; and for the entire new "Downtown Dubai", US$20 billion. Mohamed Ali Alabbar, the Chairman of Emaar Properties, speaking at the Council on Tall Buildings and Urban Habitat 8th World Congress, said in March 2009 that the price of office space at Burj Khalifa had reached US$4,000 per sq ft (over US$43,000 per m2) and that the Armani Residences, also in Burj Khalifa, were selling for US$3,500 per sq ft (over US$37,500 per m2). The completion of the tower coincided with a worldwide economic slump and overbuilding, causing it to be described as "the latest ... in [a] string of monuments to architectural vacancy."
Current records
* Tallest skyscraper to top of spire: 828 m (2,717 ft) (previously Taipei 101 – 509.2 m/1,671 ft)
* Tallest structure ever built: 828 m (2,717 ft) (previously Warsaw radio mast – 646.38 m/2,121 ft)
* Tallest extant structure: 828 m (2,717 ft) (previously KVLY-TV mast – 628.8 m/2,063 ft)
* Tallest freestanding structure: 828 m (2,717 ft) (previously CN Tower – 553.3 m/1,815 ft)
* Building with most floors: 160 (previously Willis Tower – 108)
* World's highest elevator installation
* World's fastest elevators at speed of 64 km/h (40 mph) or 18 m/s (59 ft/s) (previously Taipei 101 – 16.83 m/s)
* Highest vertical concrete pumping (for a building): 606 m (1,988 ft)(previously Taipei 101 – 449.2 m/1,474 ft)
* Highest vertical concrete pumping (for any construction): 606 m (1,988 ft) (previously Riva del
Garda Hydroelectric Power Plant – 532 m/1,745 ft)
* The first world's tallest structure in history to include residential space
* Highest outdoor observation deck in the world (124th floor)
* World's highest mosque (located on the 158th floor)
* World's highest installation of an aluminium and glass façade, at a height of 512 m (1,680 ft)
* World's highest swimming pool (76th floor) (previously Shanghai World Financial Center – 85th floor)
History of height increases
Burj Khalifa compared to some other well-known tall structures
A visual comparison of Burj Khalifa's (far right) height with that of surrounding buildings at dusk There are unconfirmed reports of several planned height increases since its inception. Originally proposed as a virtual clone of the 560 m (1,837 ft) 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 808 m (2,650 ft) 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.[citation needed] 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.
Delay
Emaar 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 design
The 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 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, act as an independent verification and testing authority for concrete and steelwork.The design of Burj Khalifa is derived from patterning systems[clarification needed] embodied in Islamic architecture. 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 1.5 m (4.9 ft).
The spire of Burj Khalifa is composed of more than 4,000 tonnes (4,400 ST; 3,900 LT) of structural steel. The central pinnacle pipe weighing 350 tonnes (390 ST; 340 LT) was constructed from inside the building and jacked to its full height of over 200 m (660 ft) 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 have the artwork of 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 142,000 m2 (1,528,000 sq ft) 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.
The hotel interior will be decorated by Giorgio Armani. An Armani Hotel, the first of four by Armani, will occupy 15 of the lower 39 floors. The hotel will be opened on 18 March 2010. whereas the Corporate Suites and offices, will be opened from March onwards. The Sky Lobbies on 43 and 76 floors will house swimming pools.
However, Burj Khalifa was opened on 4 January 2010.
Architecture and design
The 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 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, act as an independent verification and testing authority for concrete and steelwork.The design of Burj Khalifa is derived from patterning systems[clarification needed] embodied in Islamic architecture. 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 1.5 m (4.9 ft).
The spire of Burj Khalifa is composed of more than 4,000 tonnes (4,400 ST; 3,900 LT) of structural steel. The central pinnacle pipe weighing 350 tonnes (390 ST; 340 LT) was constructed from inside the building and jacked to its full height of over 200 m (660 ft) 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 have the artwork of 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 142,000 m2 (1,528,000 sq ft) 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.
The hotel interior will be decorated by Giorgio Armani. An Armani Hotel, the first of four by Armani, will occupy 15 of the lower 39 floors. The hotel will be opened on 18 March 2010. whereas the Corporate Suites and offices, will be opened from March onwards. The Sky Lobbies on 43 and 76 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 recieves its first residents from, February 2010,they will be among the first of 25,000 people who will live there. The outdoor observation deck, opened on 5 January 2010, is the highest in the world, at 442 m (1,450 ft). Tickets are time stamped at 30-minute intervals, on specific days, in order to carefully manage the daily rush of sightseers. Introductory ticket price is AED 100 for adults and AED 75 for children up to 12 years.
Burj Khalifa is expected to hold up to 25,000 people at any one time. A total of 57 elevators and 8 escalators are installed, the fastest rising and descending at up to 10 m/s (33 ft/s). Engineers had considered installing the world's first triple-deck elevators, but the final design calls for double-deck elevators. 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.
Maintenance
Burj Khalifa is expected to hold up to 25,000 people at any one time. A total of 57 elevators and 8 escalators are installed, the fastest rising and descending at up to 10 m/s (33 ft/s). Engineers had considered installing the world's first triple-deck elevators, but the final design calls for double-deck elevators. 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.
Maintenance
To 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 1,500 kg (3,300 lb) 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.
Dubai Fountain
Outside, 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 275 m (900 ft) long and shoots water 150 m (490 ft) 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.
Burj Khalifa park
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.
Dubai Fountain
Outside, 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 275 m (900 ft) long and shoots water 150 m (490 ft) 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.
Burj Khalifa park
Burj Khalifa is surrounded by an 11 ha (1,200,000 sq ft) park. 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 15,000,000 imp gal (68,000,000 L) annually. WET designers, who also developed the Dubai Fountain, developed the park's six water features.
Construction
The tower was constructed by a South Korean company, Samsung Engineering & Construction, which also did work on the Petronas Twin Towers and Taipei 101. Samsung Engineering & Construction is building the tower in a joint venture with Besix from Belgium and Arabtec from UAE. Turner is the Project Manager on the main construction contract.
The primary structural system of Burj Khalifa is reinforced concrete. Over 45,000 m3 (58,900 cu yd) of concrete, weighing more than 110,000 tonnes (120,000 ST; 110,000 LT) 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 50 m (164 ft) deep. Burj Khalifa's construction used 330,000 m3 (431,600 cu yd) 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 532 m (1,745 ft). Burj Khalifa exceeded this height on 19 August 2007, and as of May 2008 concrete was pumped to a delivery height of 606 m (1,988 ft), 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 50 °C (122 °F). 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 controversy
Burj 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
* January 2004: Excavation commences.
* February 2004: Piling starts.
* 21 September 2004: Emaar contractors begin construction.
* March 2005: Structure of Burj Khalifa starts rising.
* June 2006: Level 50 is reached.
* February 2007: Surpasses the Sears Tower as the building with the most floors.
* 13 May 2007: Sets record for vertical concrete pumping on any building at 452 m (1,483 ft), surpassing the 449.2 m (1,474 ft) to which concrete was pumped during the construction of Taipei 101, while Burj Khalifa reached 130 floor.
* 21 July 2007: Surpasses Taipei 101, whose height of 509.2 m (1,671 ft) made it the world's tallest building, and level 141 reached.
* 12 August 2007: Surpasses the Willis Tower antenna, which stands 527.3 m (1,730 ft).
* 12 September 2007: At 555.3 m (1,822 ft), becomes the world's tallest freestanding structure, surpassing the CN Tower in Toronto, and level 150 reached.
* 7 April 2008: At 629 m (2,064 ft), surpasses the KVLY-TV Mast to become the tallest man-made structure, level 160 reached.
* 17 June 2008: Emaar announces that Burj Khalifa's height is over 636 m (2,087 ft) and that its final height will not be given until it is completed in September 2009.
* 1 September 2008: Height tops 688 m (2,257 ft), making it the tallest man-made structure ever built, surpassing the previous record-holder, the Warsaw Radio Mast in Konstantynów, Poland.
* 17 January 2009: Topped out at 828 m (2,717 ft).
* 1 October 2009: Emaar announces that the exterior of the building is completed.
* 4 January 2010: Burj Khalifa's official launch ceremony is held and Burj Khalifa is opened. Burj Dubai renamed Burj Khalifa in honour of the current President of the UAE and ruler of Abu Dhabi, Sheikh Khalifa bin Zayed al Nahyan.
Opening ceremony
The opening ceremony 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 Burj Khalifa 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.
Purpose
Burj 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 Burj Khalifa, 3 hectares (7.4 acres) of parkland, at least 19 residential towers, the Dubai Mall, and the 12-hectare (30-acre) man-made Burj Khalifa Lake.
The building has returned the location of Earth's tallest free-standing structure to the Middle East — where 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.
BASE jumping
The building has been used by several experienced BASE jumpers for both authorized and unauthorized BASE
jumping:
* In May 2008, Hervé Le Gallou and an unnamed British man, dressed as engineers, illegally infiltrated Burj Khalifa (around 650 m at the time), and jumped off a balcony situated a couple of floors below the 160th floor.
* On 8th January 2010, with permission of the authorities, Nasr Al Niyadi and Omar Al Hegelan, from the Emirates Aviation Society, broke the world record for the highest BASE jump from a building after they leapt from a crane suspended platform attached to the 160th floor at 672 m (2,200 ft). The two men descended the vertical drop at a speed of up to 220 km/h (140 mph), with enough time to open their parachutes 10 seconds into the 90 second jump.
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 15,000,000 imp gal (68,000,000 L) annually. WET designers, who also developed the Dubai Fountain, developed the park's six water features.
Construction
The tower was constructed by a South Korean company, Samsung Engineering & Construction, which also did work on the Petronas Twin Towers and Taipei 101. Samsung Engineering & Construction is building the tower in a joint venture with Besix from Belgium and Arabtec from UAE. Turner is the Project Manager on the main construction contract.
The primary structural system of Burj Khalifa is reinforced concrete. Over 45,000 m3 (58,900 cu yd) of concrete, weighing more than 110,000 tonnes (120,000 ST; 110,000 LT) 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 50 m (164 ft) deep. Burj Khalifa's construction used 330,000 m3 (431,600 cu yd) 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 532 m (1,745 ft). Burj Khalifa exceeded this height on 19 August 2007, and as of May 2008 concrete was pumped to a delivery height of 606 m (1,988 ft), 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 50 °C (122 °F). 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 controversy
Burj 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
* January 2004: Excavation commences.
* February 2004: Piling starts.
* 21 September 2004: Emaar contractors begin construction.
* March 2005: Structure of Burj Khalifa starts rising.
* June 2006: Level 50 is reached.
* February 2007: Surpasses the Sears Tower as the building with the most floors.
* 13 May 2007: Sets record for vertical concrete pumping on any building at 452 m (1,483 ft), surpassing the 449.2 m (1,474 ft) to which concrete was pumped during the construction of Taipei 101, while Burj Khalifa reached 130 floor.
* 21 July 2007: Surpasses Taipei 101, whose height of 509.2 m (1,671 ft) made it the world's tallest building, and level 141 reached.
* 12 August 2007: Surpasses the Willis Tower antenna, which stands 527.3 m (1,730 ft).
* 12 September 2007: At 555.3 m (1,822 ft), becomes the world's tallest freestanding structure, surpassing the CN Tower in Toronto, and level 150 reached.
* 7 April 2008: At 629 m (2,064 ft), surpasses the KVLY-TV Mast to become the tallest man-made structure, level 160 reached.
* 17 June 2008: Emaar announces that Burj Khalifa's height is over 636 m (2,087 ft) and that its final height will not be given until it is completed in September 2009.
* 1 September 2008: Height tops 688 m (2,257 ft), making it the tallest man-made structure ever built, surpassing the previous record-holder, the Warsaw Radio Mast in Konstantynów, Poland.
* 17 January 2009: Topped out at 828 m (2,717 ft).
* 1 October 2009: Emaar announces that the exterior of the building is completed.
* 4 January 2010: Burj Khalifa's official launch ceremony is held and Burj Khalifa is opened. Burj Dubai renamed Burj Khalifa in honour of the current President of the UAE and ruler of Abu Dhabi, Sheikh Khalifa bin Zayed al Nahyan.
Opening ceremony
The opening ceremony 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 Burj Khalifa 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.
Purpose
Burj 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 Burj Khalifa, 3 hectares (7.4 acres) of parkland, at least 19 residential towers, the Dubai Mall, and the 12-hectare (30-acre) man-made Burj Khalifa Lake.
The building has returned the location of Earth's tallest free-standing structure to the Middle East — where 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.
BASE jumping
The building has been used by several experienced BASE jumpers for both authorized and unauthorized BASE
jumping:
* In May 2008, Hervé Le Gallou and an unnamed British man, dressed as engineers, illegally infiltrated Burj Khalifa (around 650 m at the time), and jumped off a balcony situated a couple of floors below the 160th floor.
* On 8th January 2010, with permission of the authorities, Nasr Al Niyadi and Omar Al Hegelan, from the Emirates Aviation Society, broke the world record for the highest BASE jump from a building after they leapt from a crane suspended platform attached to the 160th floor at 672 m (2,200 ft). The two men descended the vertical drop at a speed of up to 220 km/h (140 mph), with enough time to open their parachutes 10 seconds into the 90 second jump.
