Components and Cladding Loads on a Sign - ASCE 7

[theshearstud]

I am currently designing a free standing wall (which I am considering to be a sign) that will be approximately 40 feet in height. This wall will serve only an aesthetic function and will take only wind loads. The wall will be framed with steel and have an aluminum mesh facade. I would appreciate your thoughts on the following:

1. What wind loads would be appropriate to use for designing the secondary members (in this case studs or girts) that are to support the aluminum mesh? My intuition tells me components and cladding, but ASCE 7-05 makes no reference to C&C for signs.
2. If the answer to the above question is to use the C&C provisions for a building, would I only account for the external pressure coefficient and neglect the internal?
3. If the answer to question 1 is use the C&C provisions for a building, would it be ok to consider an effective area (for the aluminum mesh) equal to the entire mesh area spanning the secondary members (assuming there will be load sharing amongst this monolithic piece).

I appreciate all of your time!

Nick

 

[asixth]

Yeah, it needs a C&C load and should have a co-efficient of at least 2. I think the pressure co-efficient for freestanding structures can vary between 1.3 to 1.5 depending on aspect ratio and clearance above the ground.

 

[azcats]

I don't have my ASCE 7 in front of me, but I believe it's figure 6-20 that specifies wind loads on freestanding signs and walls. Found one online...it is 6-20.

Have fun with the Cf on Case C depending on your wall height:length ratios.

 

[charliealphabravo]

The force coefficients for sign design are provided since it is a simple lateral force resisting system. I don't see that C&C is appropriate except perhaps for some cladding that you are attaching to the sign.

 

[dcarr82775]

If the aluminum mesh is really a mesh, the wind pressures will be lower.

 

[theshearstud]

Thanks for all your input. It is a mesh, but we are accounting for possibility of icing and giving the owner the option to hang signage on this wall, so we are designing it to be solid.

 

[wannabeSE]

In the past, I have used the end zone loading from Load Case C in figure 6-20 to design all of the C&C on a fence. I think in some (many) cases, the Components and Cladding wind load for a building might be less than the forces for freestanding walls. If you use Components and Cladding wind load, consider using the positive force on one face with the negative force on the opposite face simultaneously.

 

[SAIL3]

I would use a drag coefficient of 2.0(total) and move on.....

 

[theshearstud]

Thanks all