Hi Bernd,
thanks for the info.
No controlling-engineer (Prüfingenieur) in CH:
Thats interesting, I didnt knew that.
But we must deliver our stuff to the local government for checking (Baueingabeplan).
Air density:
Thats a good point, thanks for this. I found a reduction formula
in a swiss chimney-calculation. At +2000 m the density (and the windforce)
reduces by 20%. Thats good.
In the last two days we have got tons of documents from Swisscom
(SIA/Eurocode/design-manuals...)
At the moment I discuss with my colleagues about statics.
We have three problems.
First:
Site location is in Adelboden-Sillerenbühl at the top of a mountain (in german: Kammlage).
The formula for calculating the effective static pressure is
qK=cd*cf*qp0
SIA gives
qp0=3,30 kN/m^2 at +2000 m (more then 330 km/h wind-speed)
cf: factor >1 for topographie
cd: factor > 1 for turbulence
For calculating the turbulence factor cd, SIA261 points to SIA-DO188, when using
the formulas I get a turbulence factor of 2,6, which is far to high. Antenna systems
have a very high stiffness (eigenfrequency approx 1,7 Hz, otherwise the link of
the radio mirrors would break due to much deflection). The cd should be approx 1,2.
Second:
In germany we must calculate two different load combinations:
self-weight+100% wind-load
self-weight+100% ice-load + 60% wind-load on changed geometry (due to ice)
I have no idea how to get icing-parameters of structures on mountains.
Third:
As far as I have understood the SIA, a earthquke-calculation is mandatory in switzerland.
Is that right? The antenna-mast has only a height of 16 m, this is not a skyscraper...
And our CAD-technicians have a problem. Swisscom wants 3D-views of some steel parts.
But they have done only 2D-drawings on autocad the last years. Oooops...
So far so good.
BTW: Sillerenbühl is a nice place
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