When the Burj Khalifa was completed in Dubai in 2010, it became the tallest building in the world by a considerable margin, beating the previous record holder, Taipei 101 in Taiwan, by more than 300 m (984 ft.). The Burj Khalifa is a truly remarkable achievement. Standing 829 m (2,720 ft.) above the desert, the tower is so tall that it is able to draw cool, high-altitude air from its top to feed and ease the load on its massive air conditioning units.
However, it looks like the Khalifa’s reign as the world’s tallest building may soon come to an end. The Kingdom of Saudi Arabia is currently planning to build an even taller building near Jeddah on the Red Sea. The Kingdom Tower would be one kilometer (over half a mile) tall when completed.
The race for the sky is definitely a way for emerging economic powers to express their national pride to the world.
“Building this tower in Jeddah sends a financial and economic message that should not be ignored. It has a political depth to it to tell the world that we Saudis invest in our country.”
—Al-Waleed bin Talal, Prince of Saudi Arabia and visionary behind Kingdom Tower
How high buildings can actually go. Is a mile-high building out of the question? In fact, the Kingdom Tower was originally proposed as a mile-high building (1600 m tall) before being scaled back to 1000 m. Some designers believe that a mile-high building will eventually be built. It is just a matter of time.
The engineering challenges presented by extremely tall buildings are immense.
One of the major challenges in designing an extremely tall building is the need for so many elevators. Considering the number of stops and distance traveled in a tall building, many elevators are required to move people up and between floors. As a building design gets taller, the elevators can take up an unacceptably large portion of the interior volume of the building. The Kingdom Tower design includes a total of 66 elevators. The result is that floor space is lost to elevators and their lobbies.
A primary engineering challenge when designing a very tall building is the wind load. Wind blowing on one face of a building exerts tremendous force and this force is multiplied as the building extends upward from its base. Buildings must be designed to withstand hurricane strength winds, but even light winds can cause very tall buildings to sway at the top. This can result in motion sickness for the people inside the building so the design must work to prevent wind sway. Typically, the building’s stiff inner concrete core is sufficient to hold the building rigid against the wind. Most tall buildings, however, employ a computer controlled dampening system to mitigate sway.
Any tall building must start will a solid base. Extremely tall buildings are extremely heavy, and their weight is spread over a much smaller area than a comparably sized “short” building. Combine this with the lateral forces of wind on the structure as mentioned above and you can see that the design and construction of the building foundation is of critical importance. A very tall building will usually have a very deep and massive foundation. The building’s foundation must not only be exceptionally strong, but must also be exceptionally durable. Water and waterborne chemicals can attack and seriously deteriorate the concrete and its steel reinforcement. Wise builders incorporate Kryton’s Krystol Concrete Waterproofing Technology into their building’s foundations.
Will the Kingdom Tower become the next world’s tallest building? And even if it does, how long will it be before someone decides to build one even taller? Architects and engineers agree that the technology already exists to build a mile-high building. And new technologies are being developed all the time. For example, advanced materials such as carbon nano tubes, which are extremely light and incredibly strong, may play a role in the super tall buildings of the future. It is simply a matter of time before someone with the money and the motivation will build the next tallest building in the world.