Burj Khalifa (Burj Dubai)

Architecture Skyscrapers: Burj Khalifa (Burj Dubai). Burj Khalifa (Arabic: برج خليفة‎ "Khalifa Tower"), known as Burj Dubai prior to its inauguration, is a skyscraper in Dubai, United Arab Emirates, and is currently the tallest structure ever built, at 828 m (2,717 ft). The tower's architecture and engineering were performed by Skidmore, Owings and Merrill of Chicago, with Adrian Smith as chief architect, and Bill Baker as chief structural engineer. Subsequently, in a surprise move at its opening ceremony, the tower was renamed Burj Khalifa, said to honour the UAE President Khalifa bin Zayed Al Nahyan for his crucial support.

Due to the slumping demand in Dubai's property market, the rents in the Burj Khalifa plummeted 40% some ten months after its opening. Burj Khalifa has been designed to be the centrepiece of a large-scale, mixed-use development that would include 30,000 homes, nine hotels such as The Address Downtown Dubai, 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 total cost for the project was about US $1.5 billion; and for the entire "Downtown Dubai" development, 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).

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 tower is designed by Skidmore, Owings and Merrill, which also designed the Willis Tower (formerly the Sears Tower) in Chicago and the new One 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. 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. 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. The design of Burj Khalifa is derived from patterning systems embodied in Islamic architecture. The tower is composed of three elements arranged around a central core. There are 27 terraces in Burj Khalifa. 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 (4.9 ft).

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 4,000 tonnes (4,400 ST; 3,900 LT) of structural steel. 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 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. A 304 room Armani Hotel, the first of four by Armani, occupies 15 of the lower 39 floors. 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. An outdoor zero-entry swimming pool will be located on the 76th floor of the tower. Burj Khalifa will receive its first residents from February 2010. Burj Khalifa is expected to hold up to 35,000 people at any one time. 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^[61] 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 system

The Burj Khalifa's water system supplies an average of 946,000 l (250,000 USgal) of water per day through 100 km (62 mi) of pipes.

Air Conditioning

The air conditioning system draws air from the upper floors where the air is cooler and cleaner than on the ground.

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. Unmanned machines will clean the top 27 additional tiers and the glass spire. The tower was constructed by South Korean company, Samsung Engineering & Construction, which also did work on the Petronas Twin Towers and Taipei 101.^[85]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. 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. In May 2008 concrete was pumped to a then world record 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. 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. CTLGroup, working for SOM, conducted the creep and shrinkage testing critical for the structural analysis of the building.

The consistency of the concrete used in the project was essential. 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.