Determine wind forces on banners, different from flag wind forces
Determine wind forces on banners, different from flag wind forces
(OP)
I'm designing some flag poles for a banner that stretches across a street. I've reviewed the ANSI/NAAMM 1001-07 document which addresses wind forces on flags quite well. It does not address wind forces on a banner supported on both sides, which acts more like a parachute than the wind forces on a flag. Using the ASCE 7-05 wind forces for a solid sign seems overkill, as the banner obviously gives more than a solid sign. Does anyone have equations they can reference for this type of loading?






RE: Determine wind forces on banners, different from flag wind forces
Think of it this way. What would act as a better parachute? A parachute that curves to form a dome or a flat plate?
If you've cut slits in the banner it would help.
Unfortunately, I haven't personally run across literature on this.
RE: Determine wind forces on banners, different from flag wind forces
RE: Determine wind forces on banners, different from flag wind forces
I have found that much of what the sign industry specifies for this type of thing is not very accurate.
I have often also limited the loads applied to 20 to 50% above the published tearing strength of the fabric. Sometimes this gives a more economical design.
Dont forget that the supports will deflect thus increasing the banner deflection and reducing the catenary tension.
RE: Determine wind forces on banners, different from flag wind forces