21 August 2010

Wind loading: science or myth?

Three researchers of the TU Delft have written a very interesting paper on the topic of facade and roof wind loading, with the title: 'Towards a reliable design of facade and roof elements against wind loading'. The paper, published in 2004, is a good starting point for some comments on the matter.

Geurts, van Staalduinen and de Wit very rightly point out that 'current building practice, including the building codes, is still not able to safeguard against local wind loads for every situation'. Wind loading codes, according to the paper, fall short on three main issues:
  • Many buildings are not covered by the typical square or rectangular plan shapes appearing on the building codes. In these cases wind tunnel experiments are the natural option, but an accepted and clear procedure on how to conduct and analyze wind tunnel measurements is not available yet.
  • Pressure equalization plays an important role in the design of roof and facade elements, but it may increase the total wind loading. Such effect is not well covered in our codes.
  • The effect that neighbouring buildings have on the local wind loads is not included in our standards, and there isn't an agreed procedure on how to measure it in a wind tunnel. 
To be continued...

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