The Physics of Tall Structures: Guangzhou TV & Sightseeing Tower

Another gargantuan structure is to be introduced to us soon. It is taller than Canada's CN Tower, and its name is Guangzhou TV & Sightseeing Tower, also called Canton Tower. Guangzhou, China is a city that will host the 2010 Asian Games. Standing 610m tall, almost 60m taller than CN Tower, Canton Tower is currently under construction and due to be completed in late 2010. The most notable feature of this enormously tall tower is the combination of column rings and diagonals that make people think about spider webs. Not only do they contribute to the dynamic look of the tower, but they are also important in the physics of Canton Tower. These immense layers of steel make up the lattice structure that the tower has. (A lattice structure derives its strength from its double curvature.) This hyperboloid structure of Canton Tower derives its hyperboloid geometry from the two ellipses, one at foundation level and the other at an imaginary horizontal plane just above 450 metres. The tightening caused by the rotation between the two ellipses forms the characterizing "waistline" of the tower, and a densification of material. This means that the lattice structure, which at the bottom of the tower is porous and spacious, becomes denser at waist level. The waist itself is tightened, like a twisted rope; further up the tower the lattice opens again, accentuated here by the tapering of the structural column-tubes. The base of the structure must not be forgotten. The core of Canton Tower consists of a concrete elliptical shaft with a short and long diameter of 15.6m and 18.6m respectively, that has been constructed with the help of a sliding formwork.

Informative Websites:
http://en.wikipedia.org/wiki/Guangzhou_TV_%26_Sightseeing_Tower
http://gztvtower.info/
http://www.gztvtower.info/03b%20Engineering.htm