Footing Design for base (ground) mounted sign 1

[REDPres]

My local church is installing a 5'x8' internally illuminated sign to be mounted on the ground in a masonry casing with a poured concrete footer. My question is... for windload considerations, what are the calculations needed to determine correct footing size? I have searched the treads and researched many projects about POLE mounted signs and understand the application of them, but I cannot find anything on base mounted signage. Can someone point me in the right direction?

 

[MotorCity]

Theoretically, there are two loading conditions that you could check. The first is the overturning moment of the sign created by the wind pressure. Whether the sign is on a pole or on the ground, a bending moment about the base of the structure will be produced. Secondly, the weight of a structure will create a bearing pressure (probably negligible in this case) on the soil below. Both of these criteria are used when sizing a footing.

However, based on the situation you have described, I would not expect the foundation to be much larger than the sign itself.

All of the sign manufacturers that I have worked with in the past design their own foundations and submit shop drawings/calculations for review. One thing to keep in mind is that regardless of the foundation depth required by calculations, make sure that it lies below the frost line in your area (if applicable).

Good luck.