Height of Skyscrapers

[brassmonkey]

What limitations are there on the maximum height of a building?  Are skyscrapers limited by the load bearing capacity of the ground,  the weather,  weight of the floors,  cost, or what?

[vehelpfulguy]

One of the original limitations of the height of the twin towers was the arrangement of the lifts.

Tall buildings are generally fairly tall and thin (like the twin towers) so floor space is expensive and at a premium. 

Obviously if you have a building of say 100 floors you need at least 4 lifts to serve the building, and four lift shafts take up a fair bit of space.

But you cannot have lifts that serve all the floors from 1 to a 100, or the people who get in on floor 1 who want say floor 93 are going to get pretty fed up stopping at all the floors below. 

So what you do is have lifts that serve floors 1 to 50, and other lifts that serve floors 50 to 100.

But the lifts that serve floors 50 - 100 still need to go from the ground floor to floor 50, to start serving the upper floors.

So that is another 4 lift shafts, so you are now up to 8 lift shafts.

If the building goes even higher then you need lifts to serve those floors above 100, so that is another 4 lift shaft, so you are up to 12 lift shafts, and so on.  

But I guess the real limit is a practical one, building a tall building is expensive, and their are all sorts of safety and security issues, particularly after 9/11.              

[Cathyhuns]

I saw a TV programme once which said that you can often date buildings from their height. When buildings were made of wood, because brick and stone were too expensive and not reliably strong, buildings could only be 2 or 3 storeys high as wood cannot support anything more.  The next limit was 4 or 5 storeys as people won't walk any higher on a regular basis.  Once lifts were invented the next limit was about 8 to 10 storeys as anything higher in a stone or brick building means the foundations are so thick that the ground floor is used up.  Steel framed buildings solved that one and the next limit was the stiffness of the buidling and how much is swayed in the wind - if it moves too much the inhabitants feel sea sick.

If you look around big, older cities you can usually pick out the different stages of buildings on this basis.

[CT]

You are limited by the difference in air pressure between the top and bottom of the building. Don't know if anyone saw that programme on the bbc in, mabye, May. It was all about skyscrapers. Can't remember what it was called.

[CT]

This is the one. It was presented by Alann Yentob. Really interesting. Watch it if it's repeated.

[CT]

Oops, Failed to put the link in.
http://www.bbcworld.com/content/template_clickpage.asp?p ageid=2659&home=1