ASCE7 Wind Load on Lattice Framework and Trussed Tower
ASCE7 Wind Load on Lattice Framework and Trussed Tower
(OP)
In regards to ASCE7 -05 or -10 do I have the following correct?
Lattice Framework:
Ratio of Solid Area to Gross Area - Use area of of the face of the elevation (or plane) that you are analyzing. Meaning that if you had a square section tower the solid are would only count the windward face of the front member. You would not count the front and back windward member face areas.
Area Af - This area includes both the windward face area of the front and back members.
Trussed Tower:
Ratio of Solid Area to Gross Area - Use area of of the windward face of the elevation (or plane) that you are analyzing. Meaning that if you had a square section tower the solid are would only count the windward face of the front member. You would not add the front and back member face areas.
Area Af - This area includes the windward face area of the front members ONLY.
So the difference is that Trussed towers deal with the projected area on a plane for both the ratio and the force (almost as if shielding is already considered) where as lattice frame work uses the projected area for the solid ratio but then applies the wind to all members windward face.
Thanks in advance!
Lattice Framework:
Ratio of Solid Area to Gross Area - Use area of of the face of the elevation (or plane) that you are analyzing. Meaning that if you had a square section tower the solid are would only count the windward face of the front member. You would not count the front and back windward member face areas.
Area Af - This area includes both the windward face area of the front and back members.
Trussed Tower:
Ratio of Solid Area to Gross Area - Use area of of the windward face of the elevation (or plane) that you are analyzing. Meaning that if you had a square section tower the solid are would only count the windward face of the front member. You would not add the front and back member face areas.
Area Af - This area includes the windward face area of the front members ONLY.
So the difference is that Trussed towers deal with the projected area on a plane for both the ratio and the force (almost as if shielding is already considered) where as lattice frame work uses the projected area for the solid ratio but then applies the wind to all members windward face.
Thanks in advance!






RE: ASCE7 Wind Load on Lattice Framework and Trussed Tower
RE: ASCE7 Wind Load on Lattice Framework and Trussed Tower
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RE: ASCE7 Wind Load on Lattice Framework and Trussed Tower
Ron -
Response is leading me to beleive that I have it backwards. Let me explain further.
Lattice Framework:
Ratio of Solid Area to Gross Area - Use area of of the face of the elevation (or plane) that you are analyzing. Meaning that if you had a square section tower the solid are would only count the windward face of the front member. Update:[/i] Meaning if there is an angle on the front face you have the area of the windward face of this angle. The angle that is on the back face (say 18" back) and is covered by this angle does not contribute to the solid area.[/i] You would not count the front and back windward member face areas.
[u]Area Af - This area includes both the windward face area of the front and back members. Update: Meaning the angle on the front face receives wind pressure and the angle on the back face receives pressure even though its is 'covered' by the front face angle.
Trussed tower:
Ratio of Solid Area to Gross Area - same as Lattice frame work.
Area Af - Use the same solid area as used in the Ratio above. Do not apply wind load to members 'covered' by members on the front face of the tower.
This is still correct or do I have this backwards?
Thanks again!
EIT
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