solid area to gross area ratio question in trussed tower wind load calcs.

[chrislaope]

Good morning everybody,

In wind load calculation for a square trussed tower which supporting a tall casing like structure, when calculating the solid area to gross area ratio (ASCE7 -05 Figure 6-23), do you take the solid area of the casing into account or just consider trussed tower solid area in the solid area to gross area ratio calculation? (see attached)

Thanks.

 

[LOKSTR]

No. Just the tower members. The casing in this case will be treated as appurtenances.
Also, take into consideration if the tower members are rounded instead of angle shapes.