Burj Khalifa
Burj Khalifa, mixed-use skyscraper in Dubai, United Arab Emirates, that is the world’s tallest building, according to all three of the main criteria by which such buildings are judged (see Researcher’s Note: Heights of Buildings). Burj Khalifa (“Khalifa Tower”), known during construction as Burj Dubai, was officially named to honor the leader of the neighbouring emirate of Abu Dhabi, Sheikh Khalifa ibn Zayed Al Nahyan. Although the tower was formally opened on January 4, 2010, the entirety of the interior was not complete at that time. Built to house a variety of commercial, residential, and hospitality ventures, the tower—whose intended height remained a closely guarded secret throughout its construction—reached completion at 163 floors and a height of 2,717 feet (828 meters). It was designed by the Chicago-based architectural firm Skidmore, Owings & Merrill. Adrian Smith served as architect, and William F. Baker served as structural engineer for this building.
The building, modular in plan, is laid out on a three-lobed footprint that is an abstract rendering of the local Hymenocallis flower. The Y-shaped plan plays a central role in the reduction of wind forces on the tower. A hexagonal central core is buttressed by a series of wings, each with its own concrete core and perimeter columns. As the tower increases in height, the wings step back in a spiral configuration, changing the building’s shape at each tier and so reducing the effect of the wind on the building. The central core emerges at the tower’s top and is finished with a spire, which reaches more than 700 feet (200 meters). The spire was constructed inside the tower and hoisted to its final position using a hydraulic pump. At the foundational level, the tower is supported by a reinforced concrete mat nearly 13 feet (4 meters) thick, itself supported by concrete piles 5 feet (1.5 meters) in diameter. A three-story podium anchors the tower in place; the podium and two-story basement alone measure some 2,000,000 square feet (186,000 square meters) in their own right. The tower’s exterior cladding is made up of aluminum and stainless-steel panels, vertical stainless-steel tubular fins, and more than 28,000 hand-cut glass panels. A public observation deck, called “At the Top,” is located on the 124th floor.
Upon its inauguration in January 2010, Burj Khalifa easily surpassed the Taipei 101 (Taipei Financial Center) building in Taipei, Taiwan, which measured 1,667 feet (508 meters), as the world’s tallest building. At the same time, Burj Khalifa broke numerous other records, including the world’s tallest freestanding structure, the world’s highest occupied floor, and the world’s highest outdoor observation deck.