A mile-high tower would not just be a new structure, but a new technology.
- Frank Lloyd Wright originally proposed The Mile-High Illinois in the 1950s.
- Innovations in construction materials and elevators are necessary to reach the one mile height and beyond.
- We may see the first mile-high skyscraper by the middle of the 21st century.
Frank Lloyd Wright’s The Mile-High Illinois<p>One of the first legitimate plans to build a mile-high tower that wasn't some megalomaniac's fever dream (maybe his was too), was famed architect Frank Lloyd Wright's The Illinois. </p><p>On October 16th, 1956 at the Sherman House Hotel in Chicago, Wright at 89 years old presented his design for what he conceived to be the tallest skyscraper in the world, an incredible spire shooting one mile high. The structure proposed to stand 528 floors and 5,280 feet (1,609 meters) tall. Behind him stood an illustration that measured 25 feet (7.6 meters) tall with the skyscraper's dimensions drawn at a scale of 1/16 inch to the foot. The Illinois' dimensions would have been astronomical at the time, with: </p><ul><li>528 floors </li><li>76 elevators </li><li>Gross floor area (GFA): 18,460,106 ft² (1,715,000 m²)</li><li>100,000 occupants </li><li>15,000 parking spaces </li><li>100 helicopter landing pads </li><li>Architectural height of 5,280 ft (1,609.4 m)</li><li>Tip antenna height of 5,706 ft (1739.2 m)</li></ul><p>"This is The Illinois, gentlemen… In it, will be consolidated all government offices now scattered around Chicago," Wright proclaimed.</p>
Frank Lloyd Wright presents The Mile High Illinois at the Sherman House Hotel in Chicago
Credit: Alamy Photos<p>Wright in an exemplary display of showmanship unveiled the first proposal for the mile-high tower. He believed that he'd found a method to construct the tower out of two principles he coined "tenuity" and "continuity." With these methods he'd believed he would be able to construct the tower out of reinforced concrete and steel.</p> <p>The general principles between these two ideas is characterized by Wright's designs in which he used a "taproot" foundation to support the central load of the structure. </p> <p><a href="https://www.chicagotribune.com/columns/ct-frank-lloyd-wright-mile-high-met-0528-20170528-column.html" target="_blank" rel="noopener noreferrer">Chicago Tribune's Blaire Kamin</a> described it as follows: </p> <p> "The Mile-High didn't simply aim to be tall. It was the ultimate expression of Wright's "taproot" structural system, which sank a central concrete mast deep into the ground and cantilevered floors from the mast. In contrast to a typical skyscraper, in which same-size floors are piled atop one another like so many pancakes, the taproot system lets floors vary in size, opening a high-rise's interior and letting space flow between floors."</p>
Building technology for a 1-mile skyscraper<p>The undefeated champion of the skies right now is the Burj Khalifa in Dubai, which stands at 2,717 feet (roughly half a mile) and is the tallest building in the world.</p><p>Although take that with a grain of dusty salt—only 1,916 feet of the Burj Dubai is occupiable space, the rest is vanity height, meaning nearly 800 feet is non-occupiable space. That represents 29 percent of the building's height. </p><p>So let's get back to real contenders for a mile high.</p><a href="https://www.technologyreview.com/2018/08/20/2343/get-ready-for-more-and-taller-skyscrapers/" target="_blank" rel="noopener noreferrer">Researchers at MIT Technology Review</a> used data from the experts at the Council on Tall Buildings and Urban Habitat and predicted that there is a 9 percent chance that a building exceeding a mile will be built by 2050. They've also predicted that by 2050, nearly 6 billion people will live in cities. Already we're seeing that urban areas in China and the Middle East are continually building up, not out.
Credit: Jonathan Auerbach and Phyllis Wan, International Journal of Forecasting Vol. 36, Issue 3<p>There are three major construction and stability aspects that must be dealt with if we're to reach a vertical mile. Those are:</p><ul><li>Dampening wind sway </li><li>Elevator speed and length </li><li>Construction materials </li></ul><p>The tallest skyscrapers all employ a tapered top design. This serves both a utilitarian and structural purpose. It's simply not possible to take pre-existing buildings and just double their height. </p><p>A mile-high tower would not just be a new structure, but a new technology. </p><p>Putting aside Burj Khalifa's vanity height for a moment, we have to admire its structural ingenuity. Designed by architect Adrian Smith and structural engineer William Baker at Skidmore, Owings and Merrill, the structure's foundational approach is a buttressed core – which is a hexagonal concrete core that frays out into three triangle buttresses. This was one inventive solution they made to support such a great height. </p><p>But that only solves one issue. </p><p><strong>Diverting winds at high elevations</strong> </p><p>What might be a slight breeze on the ground floor can turn into a windstorm in greater heights. Aside from the fundamentals of stability, occupants also need comfortability. Most building sway is harmless to the structural integrity of the building. But the last thing anyone wants is to feel like they're in the midst of a tornado 500 floors above ground level. </p><p>Architecture, engineering, and construction (AEC) professionals calculate estimated wind sway from a building's height and incorporate that into the design. Buildings are often made to withstand cataclysmic 500 to 1000 year inclement weather disasters. </p><p>To deal with wind, you either confuse it by spinning it around the building in creative structural ways or you use a mass dampener.</p><p>A mass dampener is a counterweight suspended somewhere in the building to counteract and balance the movement from the outside. For example, the Taipei 101 Tower employs a <a href="https://gizmodo.com/how-a-730-ton-ball-kept-the-second-tallest-building-fro-5019046" target="_blank">730 ton orb </a>pendulum that sways back and forth to balance wind from storms and typhoons. </p><p>Aerodynamic vortexes of wind can exert dangerous amounts of pressure and vibrations on a building. Air currents can be unpredictable, so rather than guess what could happen to the building, AEC professionals need to calculate it directly into the design. If it's not a mass dampener, it'll be a mix of structural fins, curves, and asymmetrical floors. </p><p><strong>Elevator speed and stability</strong> </p><p>The logistical obstacles of moving thousands of people in a mile-high skyscraper is one of the biggest challenges. To reach the floor at the top of a mile-high building with current technology would require people to change elevators multiple times. </p><p>The current figure for elevators runs at 1,600 feet as wire suspension ropes cannot support their own weight and any additional weight after that point. Aside from the technical limitations, needing multiple elevator lobbies would take up too much valuable space. </p><p>A few years ago, Finnish elevator company Kone developed a carbon fiber cable, UltraRope that they believe could double the distance of an elevator rope. This would be enough to get those would-be mile-high penthouse residents to their sky digs. </p><p>Beyond the old school cable elevator, others have floated ideas about a looped system that could pull elevators up, down and sideways. This could increase the building's usable area by 25 percent. </p><p><strong>New structural materials</strong> </p><p>Concrete has served us well for thousands of years. It's time to rethink what materials we can use. Engineers are looking at materials like carbon fiber, an extremely lightweight and strong material. </p><p>Carbon fiber is a polymer composed of thin strands of carbon atoms bound together in a unique crystalline formation. It is far lighter than steel, five times stronger and has double the stiffness. Currently carbon fiber is used in a number of manufacturing processes ranging from aircraft wings to bike frames. Carbon fiber and other related composite materials weigh very little but can take on heavy bearing loads.</p>