Mike’s extremely well-illustrated talk was about skyscrapers – there are about 4,800 in the world!
The idea of building tall buildings is not new – even in biblical times they thought up the Tower of Babel!
In more modern times the tower of Lincoln Cathedral, the Eiffel Tower, the Chrysler Building and the Empire State Building, both in New York, were examples.
It seems that bell towers for religious buildings (e.g. the Leaning Tower of Pisa) were intent on reaching Heaven, but in more recent times the tall buildings are to do with making money.
Early tallish buildings were timber framed but they had a tendency to decay and fall down or, in some cases, to burn down. Then Shrewbury Flax Mill was built using iron columns as its framework, which cost much more than timber, but it is still standing and perhaps taught other architects a lesson.
* The first essential for a skyscraper is a steel framework with other materials added to it e.g. the Reliance Building has no load-bearing outer walls.
* The second essential for a sky scraper is a passenger lift, because people do not want to or are not able to climb hundred of stairs (but the lift must be safe!).
The first lift with a safety brake was put into a five-storey apartment block in (of course) New York.
After a fire which devastated the second largest city in the U.S.A., Chicago, there they began to build upwards because the business district was confined to a smallish area. Many offices were needed for the businesses to make money so skyscraper were the answer.
Then it seems that vanity took over and there was a fierce drive to have the world’s tallest building. The Chrysler Building in New York was erected. It was 1046 feet high, the tallest in the world – but not for long!
A year later the Empire State Building had an extra five floors to make it 1050 feet high, then someone thought that if Chrysler added an aerial mast it would still be tallest, so two more floors were added that took it up to 1250 feet, and the Empire State was the tallest for 43 years! The building was a triumph of organisation using 3,400 workers who were able to build four floors a week! Then the film “King Kong” gave it worldwide status!
So a steel frame with glass outer walls became the new style until the World Trade Centre changed to a steel outer frame, leaving the inner floors less confined.
Tall buildings have their problems – they tend to sway in the wind and to oscillate, but a large weighty ‘pendulum’ has been designed to counteract this.
At the moment the Burj Khalifa in Dubai (838metres) is the tallest skyscraper in the world – but for how long?