There are some great stories when it comes to the evolution of the lift. There was Elisha Otis who ceremoniously (and sensationally) had the lift cable cut while he was in the lift to prove his new brake system worked. Or the fact the lift shaft was actually invented 4 years before the first modern lift. More poignantly, the lift (or elevator in American-speak) enabled taller buildings and denser cities which some argue has led to a fatter populace.
Archimedes’ screw is the precursor of lifts, using technology to lift up, or elevate, items efficiently. And as technology boomed, so too the height of buildings. There are a dizzying array of types of lifts now, and their presence is being felt even inside our homes. To get more people up faster, there are double decker lifts (no triples as yet) as well as sky lobbies so that occupants need to change lifts to go higher. The limited height of lifts enables 3-stage buildings which are a conglomerate of dumped buildings on top of each other in order to reach ever higher (hotels on residential on commercial).
Currently the tallest building in the world, the Burj Khalifa in Dubai, standing at 828 metres has 57 lifts and has a top speed of 10 metres per second and this building has the record of the longest travel distance of a lift – 504 metres. (The fastest lift however still belongs to Taipei 101 in Taiwan at 16.83 m/s). This appears to be the limit, or was…
Buildings have now been restricted (more-or-less) by the current cable technology – it is not hard to imagine how heavy the cables are. Steel cables (called ropes) account for around 3/4 of the moving mass. The larger the travel distance, the longer the ropes, the heavier the mass, the larger the motor, and the more expensive it is. And counterweights only do so much. Eventually, steel could snap under such loads.
On 22 May 2013 works commenced on site on the Kingdom Tower in Jeddah, Saudi Arabia. Its height? 1000 metres.
Taller however does not necessarily mean better. Neither does it necessarily mean prettier. To prove this, one only has to look at the proposed Changsha Tower in China, designed in a Brutalist style and reminiscent of the older Adventures of Superman with George Reeves. Thankfully, construction has stalled on that project.
But now – buildings are set to take the next leap as another breakthrough in lift technology arrives. Otis, the largest lift manufacturer in the world (from the US) has been beaten to the punch by their rival Kone (Finnish) who has announced it has manufactured a system that can raise a lift up to 1000 metres, doubling the current design. Their development laboratory is actually is 333 metre deep mineshaft in Lohja and the new cable is made of carbon fibre instead of heavy steel. The weight of carbon fibre ropes (called for now the UltraRope) are 60% lighter (resulting in around a decrease in moving mass of 90% over longer distances) and have far greater tensile strength. The have a high friction coating, double the life span (also meaning less maintenance) and as a result of being lighter uses far less electricity.
Tall buildings are designed to sway but with carbon fibre resonating at a different frequency to other building materials, it means tall buildings will sway less in high winds. This means that tall buildings will not need to be shut down as often in high winds.
the sky is no limit to skyscrapers
In theory, cables do not need to remain with buildings. In 1895 it was proposed to build a tower to geostationary orbit. Now space lifts are getting more attention and further development of carbon fibre could be the way using carbon nanotubes or boron nitride nanotubes which are even stronger for their weight. At the end of the cable would be a counterweight far into space. Competing forces of gravity on earth and centrifugal force from the spin of the earth would keep the cable under tension. Climber cars would then crawl up this tether into space.
On other celestial bodies where gravity is weaker (such as the Moon or Mars) currently available Kevlar would be strong enough.
All of this means taller buildings and perhaps the end of earth-constrained building. Either way, the term skyscraper may need to be re-named – to spacescraper.