Wind action is an important design consideration for most buildings. Several direction and terrain dependent factors are taken into account during the wind load calculation. But how can we calculate the effect of the building height?
The Eurocode 1: Actions on structures - Part 1-4: General actions - Wind loads gives guidance on the determination of wind loading. The scope of this standard is those buildings whose height is maximum 200 m.
To calculate the peak wind pressure, the Eurocode’s figures of the basic structural forms and other designer guides usually recommend taking the reference height as the maximum height of the building.
In this case, the wind pressure distribution is assumed as uniform over the whole height.
But what can we do in the case of a relatively high and slender structure, where the variation of the wind pressure along the height of the building is not negligible?
For buildings with height (h) greater than the crosswind breadth (b), the Eurocode rules provide some reduction for the wind pressure on the windward face of the building (D zone). In terms of the determination of the reference height, the code distinguishes three cases depending on the ratio h/b:
- The height of the building (h) is less than b (general case)
The reference height should be taken as the height of the building and the building should be considered to be one part
- The height of the building is greater than b, but less than 2*b
The building should be considered to be two parts: a lower part extending upwards from the ground by a height equal to b, and an upper part which is the remainder
- The height of the building is greater than 2*b
The building should be considered to be multiple parts: a lower part extending upwards from the ground by a height equal to b, an upper part extending downwards from the top by a height equal to b and middle region between upper and lower parts
However, this ‘division by parts’ rule is only used on the windward face only. For the leeward (E zone) and side walls (A, B and C zones), the reference height should be taken as the height of the building.
MasterKey: Wind Analysis
MasterKey: Wind Analysis add-on module to MasterFrame accurately generate the wind loading on 3D buildings. To determine the wind pressure, the MasterKey: Wind Analysis automatically take into account all the directional & topography parameters and the shape of the building, based on the selected site location (in UK & Ireland only) and 3D structural model.
The following short video demonstrates how can you generate the wind loading in a few steps in the MasterSeries.
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