Hello there, first time poster, long time reader.
My problem concerns the wind profile dialog in the simulation tool and what is the exact meaning of the wind speed factor and how RSA actually use it.
In the Italian code the wind profile is given as the exposure factor Ce(z), calculated as follows:
And the wind pressure load is then given as:
where Ce is the exposure factor (really ), Cp is the areodynamic factor and Cd is the dynamic factor (Cd and Cp are not relevant in this discussion). Qb is the basic cinetic pressure, as function of the reference wind's speed:
I checked it against the eurocode and it results that it derives from two other factors, the roughness factor Cr(z), and the turbulence intensity lv(z), calculated as follows:
The wind pressure load, according to EC is then given as:
where Vm is the wind velocity in fucntion of the altitude z, as follows:
As you can see, even if the final wind pressure load is equivalent in both codes, the wind profiles differes of a factor of roughly (Ce(z))^0.5, because in the Italian code the variation,functions of z, is applied at the exposure factor level Ce, otherwise in the EC it is applied at the wind velocity Vm, and therefore is squared.
My question is, what is the wind speed factor we introduce in the dialog and where it is applied?
If it is applied at the wind velocity level, so that I have to square Vm(z), it is only the roughness factor Cr(z), or is it the combination of the roughness factor Cr(z) and the turbulence intensity lv(z), i.e. (Ce(z))^0.5?
Hope to have been clear. Thank for your help.
Stefano Follador
(PS:would be nice to have a simple LaTeX editor to enter math formula in the forum!)
