Since the dawn of history man has been trying to build the 'tallest building', 'tallest tower' or 'tallest structure' in the world. There seems to be much prestige in being home to the worlds tallest. So much in fact that this is a major issue on the political agenda of many countries. Many towers claim the title, and many cities quarrel about who is the winner. During the first 90 years of this century, the USA dominated the race for the title of the tallest building in the world, and constructed a range of famous buildings that, sometimes only for a few months, and sometimes for many years, were widely recognized as being the 'tallest building' in the world. In 1974 Chicago's Sears Tower was completed, and generally seen as the 'tallest building' in the world. Sears held on to that title for over 20 years. But since the nineties the USA gets some stiff competition from Asia. In 1996 this resulted in the completion of the Petronas Twin Towers in Kuala Lumpur. From that moment on a sort of media clash was unleashed. All over the world people debated about the question which one was the tallest; Sears or Petronas. Now the answer to this question seems so easy. Just measure both buildings from bottom to top, and the tallest one gets the title. Question answered, case closed, no more debate needed? Forget it! As usual, life is not that simple. One could consider how to measure these buildings. For example, do we take in account spires and antennas? To end this discussion, the Council on Tall Buildings and Urban Habitat made a compromise. They defined 4 categories for measuring tall buildings;- Height to the structural or architectural top.
- Height to the highest occupied floor.
- Height to the top of the roof.
- Height to the top of antenna.
Burj Khalifa (Arabic: برج خليفة "Khalifa Tower"), formerly known as Burj Dubai, is a skyscraper in Dubai, United Arab Emirates, and is, at the moment, 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 and 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 architect and engineer is Skidmore, Owings and Merrill, LLP (Chicago). Bill Baker, the Chief Structural Engineer for the project, invented the buttressed core structural system in order to enable the tower to achieve such heights economically. Adrian Smith, who worked with Skidmore, Owings and Merrill (SOM) until 2006, was the Design Partner on the project.
The primary builder is South Korean Samsung C&T, who also built the Taipei 101 and Petronas Twin Towers, followed by Belgian group Besix and Arabtec from 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 is legally the Design Consultant for the tower.
The total budget for the Burj Khalifa project is about US $ 1.5 billion; and for the entire new "Downtown Dubai", US $ 20 billion. Mohamed Ali Alabbar, the CEO of Emaar Properties, speaking at the Council on Tall Buildings and Urban Habitat 8th World Congress, said 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 string of monuments to architectural vacancy."
Though unconfirmed, Burj Khalifa has been rumored to have undergone 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 discussed below. Marshall Strabala, an SOM architect who worked on the project until 2006, recently 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 currently planned 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. However, the top of the tower has a steel frame structure, unlike the lower portion's reinforced concrete.
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.
The tower is designed by Skidmore, Owings and Merrill, which also designed the Willis 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 Supervision Consultant, Engineer and Architect of Record, for its structural, facade and MEP engineering capability (MEP – mechanical, electrical and plumbing, and encompasses all fire and life safety systems within the building). In this role Hyder Consulting re-engineered structural, facades and MEP systems to suit the contractor's and local authority requirements. Hyder Consulting was also responsible for the geotechnical design of Burj Khalifa's foundations with Hyder's own geotechnical specialist, Grahame Bunce heading up a design team that included the world-renowned soil mechanics expert Harry Poulos in a peer-review role. Emaar Properties has 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 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 spiraling 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 tones of structural steel. The central pinnacle pipe weighing 350 tones was constructed from inside the building and jacked to its full height of 143 meters using a strand jack system. The spire houses plant and facilitates for communications equipments.
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 aluminum and textured stainless steel spandrels panels with vertical tubular fins. The cladding system is designed to withstand Dubai's extreme summer temperatures. Additionally, at its projected height the exterior temperature at the top of the building will 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. 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 will fill most of the remaining floors, except for a 123rd floor lobby and 124th floor (about 440 m (1,440 ft)) indoor and outdoor observation deck. 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 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[44] for Burj Khalifa have also been created by Brash Brands as well as the road show exhibition for the Armani Residences, which are part of the Armani Hotel within Burj Khalifa, which toured Milan, London, Jeddah, Moscow and Delhi.
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 1.5 tone 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.
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 colored 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.
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 tones (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 meter diameter x 43 meter 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 tones of steel re-bar, 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 compartmentalized. 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 tones 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.
So, I don't know about you, guys...but for me, it was a definite next holiday destination. Can you imagine, not just we're at the tallest building in the world, but I was more excited about what kind of view would you get from it? Wow! It would be even more complete though, if we can do some extreme things up there...no, am not talking about making love, OMG...that's gross! I was thinking about bungee jump or sky walk, like the one they have on Macau Tower. What do you think? I said, superb! See you there, guys!
^_^
Sources : www.tallestbuildingintheworld.com, Wikipedia
