Till 4th January 2010 the tallest man made structure known was the Varsaw Radio Mast tower in Gabin. But now the tallest man-made structure is Burj Khalifa, a skyscraper in Dubai that reached 828 metres (2,720 ft) in height. We have some classic man made tall structures, to name a few C N Tower, Taipei 101, Petronas Towers, Empire State, Eiffel Tower etc. But Burj Khalifa is a classic example of one of the best man made structures which is a testimony in itself of the progress made by man in various fields of technology, construction & architecture. The total cost of the Burj Khalifa project is about US$1.5 billion. Dubai", US$20 billion.As per the CEO of Emaar Properties Mr. Mohamed Ali Alabbar, the price of office space at Burj Khalifa had reached US$4,000 / sq. ft. and that the Armani Residences, also in Burj Khalifa, were selling for US$3,500 / sq ft. It is said that all the homes were booked within eight hours of opening of the tower. The cleaning system of the tower was developed in Australia at a cost of A$8 million. During construction the tower was known as Burj Dubai but later on completion it is named as Burj Khalifa after the name of leader of neighboring Abu Dhabi. He recently bailed out Dubai out of the $ 10 billion hole.
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." The Prime Minister and Vice President of UAE and the Emir of Dubai, Mr. Sheikh Mohammed bin Rashid Al Maktoum) is keen to put Dubai on world map with something really sensational," said Jacqui Josephson, a tourism and VIP delegations executive. Burj Khalifa include 30,000 homes, nine hotels 7.4 acres of parkland, 19 residential towers, the Dubai Mall, and 30-acres of man-made Burj Khalifa Lake.
There is a rumour about several changes in the planned height of Burj Khalifa since the inception. It was proposed to be a virtual clone of Grollo Tower which was proposed to be of 1,837 ft in height. It was proposed to build inthe Docklands precinct of Melbourne, Australia. The developer was Grocon, a construction company owned by the Grollo family.
The tower's architecture and engineering is done by Skidmore, Owings and Merrill. As the upperpost section of the tower did not elegently gel with the rest of the structure, the then design architect, Adrian Smith, sought and received approval to increase it to the currently planned height. As no addition floors were added with the height of the tower the architect was able to make it more slender and elegant.The South Korean company, Samsung Engineering & Construction,which also did work on the Petronas Twin Towers and Taipei 101 has constructed the Burj Khalifa. According to Adrian Smith, the design architec, the triple-lobed footprint of the building was inspired by the flower called Hymenocallis.
Alike the flower, the tower is composed of three elements arranged around a central core. As the tower rises, there are step like recessions in the walls of each of the three structures 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. 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. The total structural steel used for the spire of Burj Khalifa is estimated to be 4,000 tonnes. The central pinnacle pipe weighing 350 tonnes was constructed from inside the building and jacked to its full height of 143 metres using a strand jack system. The communications equipments are installed in the spire and operated from the spire itself. It is anticipated that around 1,000 pieces of art will decorate the interiors of Burj Khalifa. In the residential area of the tower there will be artworks of bronze / brass representing 196 countries of the world. The visitors in the lobby ca nhear a sound of water falling on leaves because of some special arrangements of the gold plated cymbals getting struck by the dripping water.
The exterior cladding of Burj Khalifa consists of 142,000 m2 (1,528,000 sq ft) of reflective glazing, aluminium, textured stainless steel and spandrel panels with vertical tubular fins. The cladding system is designed to withstand Dubai's extreme summer temperatures. Also the temperature varies from bottom to top with the top of the tower having very low temperatures in single digits. The primary structural system of Burj Khalifa is reinforced concrete. Over 45,000 m3 of concrete, weighing more than 110,000 tonnes were used to construct the concrete and steel foundation. Burj Khalifa's construction used 330,000 m3 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.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.
The consistency of the concrete used in the project was essential. To ensure that the concrete withstands the high fluctuations of temperature of the desert some extra efforts were taken. 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 structure is visible from a distance of 95 km and has total of 165 floors. Armani Hotel occupies 15 of the lower 39 floors. There is a swimming pool on the 76th floor. Total of 900 residential apartments are available which are built onwards floor no. 108. The 123rd and 124th floor will house observation deck. Corporate offices and suites will fill most of the remaining floors. Burj Khalifa is having a capacity to hold up to 25,000 people at a time. There are 57 double decker elevators and 8 escalators instaleed in this tower. To wash the windows externally a horizontal track has been installed on the exterior of Burj Khalifa on floor 40, 73 and 109. 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. The construction of Burj Khalifa was delayed due to upgrading the structure with time. 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."
With this great structure reaching maximum height in actual sense it is evident that people across the world are making progress in all walks of life. It is one more landmark achieved in the field of construction which definitely will make its ways in all books of history.
Article By - PRANAV JOSHI
Burj Khalifa - The tallest one ! Reviewed by Salil Chaudhary on 08:52 Rating: