Footing Design for base (ground) mounted sign

[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?

 

[Focht3]

It's the same process as a pole mounted sign, except there's no pole. Use the sign pole equations to calculate the air pressure based on the design wind speed (governed by the local building code), which you will multiply by the face area of the structure. You then use that horizontal force as the design shear, and the shear times the offset between the top of footing and centroid of the loaded area will give you the overturning moment.

But you will still need soil parameters in order to design the foundation...



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[GeoPaveTraffic]

REDPres;

Focht3 is correct the loads are the same as for a sign with a pole, it is just the way those loads get to the ground that is different. It may help to think of the sign as a retaining wall, with the load source being wind instead of soil.

All of the stability checks that would generally be done for a retaining wall should be checked for the sign, however, since the horizontal dead load is zero, the factors of safety for those conditions could be lower than that required by a retaining wall.

 

[ERV]

Here is an excelent reference for sign design and load calcs:

http://www.iccsafe.org/e/prodlist.html?stateInfo=adPBzjOnjObEgvya5443|25&words=106h98&go.x=22&go.y=5