Sources: Skidmore, Owings & Merrill, Chicago; CP staff
Standing at more than a half-mile tall, the world's tallest skyscraper opened on January 4 in Dubai, United Arab Emirates. The centerpiece of a large-scale, mixed-use development, the tower was constructed by South Korea-based Samsung Engineering and Construction, from a design by Skidmore, Owings and Merrill, architects for Chicago's Willis (formerly Sears) Tower and New York City's One World Trade Center (formerly Freedom Tower). (At a proposed 1,776 ft., the latter project stands to succeed the 1,454-ft. Willis as North America's tallest building.)
Said to cost approximately $1.5 billion, the 2,717-ft.-tall Burj Dubai tower not only holds the record for the tallest concrete building but also for vertical concrete pumping for any construction--1,988 ft. to the 156th floor, with the remaining structure above built of lighter structural steel. The tower also houses the world's fastest elevator, which travels 40 mph.
The primary structural system is reinforced concrete, with nearly 59,000 yd. used to construct the foundation, which features 192, 5- x 41-ft.-long piles buried more than 164 ft. deep. Designers configured the tower in a Y shape to reduce the wind forces on the structure. Each wing, with its own high-performance core and perimeter columns, buttresses the others via a six-sided central core. The result is a tower that is extremely stiff torsionally.Building the actual tower required another 431,000 yd., 55,000 metric tons of rebar, and 22 million man-hours. A high-density, low-permeability concrete was specified for the foundation, with a cathodic protection system under the mat used to minimize any detrimental effects from the corrosive chemicals in the local ground water. For the main structure, each batch was tested to ensure it could withstand the extreme pressures of the building's weight. In addition, the consistency of the product had to hold up against the Persian Gulf temperatures, which can reach 122_F. To combat this issue during pours happening in the summer months, ice was added to the mix and the product was only poured at night to take advantage of the cooler air and high humidity. The temperature between the ground and the top of the building can vary by as much as 15_F.