Whenever people think of “megastructures,” their focus inevitably lands on height or length, meaning how tall or how long the buildings are. Examples include the United Arab Emirates’ Burj Khalifa, which is currently the tallest building in the world at 2,717 feet, and Saudi Arabia’s Jeddah Tower, which is still under construction and aims to be at least 3,307 feet in height. In other instances, like The Line, a megalopolis stretching 110 miles in Saudi Arabia, the structure’s length is what leaves people in awe.
However, another dimension is equally impressive but often overlooked: depth–specifically, the foundations.
A world record. In terms of foundations, the world record isn’t in Saudi Arabia, the United Arab Emirates, or the U.S. Instead, it belongs to Malaysia. According to the Guinness World Records, the deepest building foundations in the world are those of the Petronas Towers in Kuala Lumpur in Malaysia, which reach a remarkable depth of almost 400 feet.
Guinness World Records isn’t the only organization to recognize the Petronas Towers for their deep foundations. Capital Piling, a UK company specializing in piles and foundations, also lists them as having the deepest foundations in the world, at least as of 2022.
Objective: Adapt to the terrain. The foundations of the Petronas Towers are exceptionally deep, not merely for the sake of aesthetics or in pursuit of records. According to Capital Piling, the primary reason lies in the surrounding terrain, which is “notoriously unstable.” This instability led the architects to select a concrete pile foundation, a design meant to distribute the load effectively. Engineering news site Structures Insider reports that the local soil is prone to moisture-induced expansion and shrinkage during dry periods.
“The building is situated on a dense, silty formation that overlays weathered and highly-decomposed limestone. Each tower sits on a raft that caps 104 barrette piles, which are 30 to 108 meters [98 to 354 feet] deep,” Durham Geo Slope Indicator, a geotechnical instrumentation and equipment company, says on its website. It adds, “The rafts are 4.5 meters [15 feet] thick and were cast in one pour for each tower. The designers required that the rafts be instrumented to measure the load taken by the piles and the load transmitted to the ground by the raft.”
A year’s work. Achieving an architectural milestone such as this is no simple task, especially since much of the work is hidden beneath the surface. The Petronas Twin Towers website outlines the foundation work undertaken by the company Bachy Soletanche. It says that workers spent about 12 months on this task, resulting in foundations that extend about 400 feet deep.
“Skyscrapers need strong, deep foundations that penetrate into the ground below. Given the tremendous height of the towers, the Petronas Twin Towers have a ground-breaking 120 meters (approx. 400 ft.) of solid foundation underneath its dense concrete footings,” the official website adds. To further clarify, the site includes a straightforward sketch illustrating the structure of the foundation.
The foundations of the Petronas Towers.
A well-anchored mass. The foundations of the Petronas Towers are impressive, but they’re no more remarkable than the towers they support: two skyscrapers that were the tallest buildings in the world from 1998 until 2004.
Each of the towers is 1,483 feet high, consisting of 88 stories, plus five levels of mechanical services and parking. According to the official website, each tower is estimated to weigh approximately 300,000 tons, equivalent to more than 42,800 adult elephants. It took six years and $1.6 billion to construct them.
Higher, but not deeper. Although the Petronas Towers are no longer the tallest skyscrapers in the world, the structures that now exceed their height don’t necessarily have deeper foundations. For instance, the Burj Khalifa in Dubai, which stands slightly over 2,700 feet tall, has a much shallower base, with 192 concrete piles drilled to a depth of 164 feet.
The same applies to Taipei 101 in Taiwan, which reaches a height of 1,667 feet and is supported by 380 concrete piles with a diameter of about 5 feet, extending to a depth of 262 feet. Similarly, in 2014, Jeddah Tower developers reported that the skyscraper incorporated 270 piles with diameters ranging from about 5 feet to 6 feet, reaching 344 feet below ground level.
The “king of buildings.” Guinness World Records recognizes the Petronas Towers as having the “deepest foundations for a building.” The “building” mention isn’t insignificant. Kuala Lumpur’s skyscrapers are well-known among the world’s major residential and office structures. However, the competition becomes much closer when you broaden the comparison to include other engineering feats.
In June 2022, Bangladesh officially inaugurated the Padma River Bridge, a 3.82-mile viaduct that cost $3.6 billion. The bridge was designed to connect the capital city, Dhaka, with the port of Mongla. While its length may not be remarkable, the structure is notable for its foundation. Its steel piles are driven more than 400 feet deep into the riverbed, prompting discussions at the time of its inauguration about the bridge potentially holding a “world record” among similar structures.
Image | Neil Daftary | Kevin Olson | Petronas Twin Towers
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