FOR A LONG time skyscraper structural engineers have had to take account of the effects that wind will have on the structures they are designing. Given its size, and therefore the massive surface area exposed to wind forces, this was a vital consideration for the Burj Dubai.
'We did very extensive wind tunnel testing.
We have done peer reviews on the wind tunnel performance. We then did peer reviews on those peer reviews. We had to be very thorough, ' says Mr Sang.
'One unique aspect of the wind design of the building is that it actually goes above what is called the boundary layer. The boundary layer is a thin strip around the surface of the earth where the wind speed is variable.
'Most buildings are built within the boundary layer, which goes up to 600 m. The Burj steps above that. That will be a first. Above that it stays at a constant speed with height. That is quite unusual but we have engineered to overcome that, ' he says.
Mitigation of wind loading on the Burj Dubai is partially achieved through the way the profile of the building changes as it rises up. The design concept for the tower is taken from a desert flower with a central 'stem' or core off which three 'petals' are attached. These petals each have a series of setbacks closing in on the central core as they rise, at different heights for each different petal. This creates a spiral form that prevents the high forces associated with concentration of wind load.