**Footing for Economic Design Needed**

[Dezog]

I am cureently designing a structure here in California consisting of 4 masonry columns supporting a heavy roof structure. Usingthe UBC 97, I cam up with my lateral forces acting on each column. All of the structural elements have been designed but the footing still needs to be worked on. The problem I have is how to design the footing. Using the Brian Das foundation design book, and the chapter on spread footings, my footing would have to be huge due to eccentricity e = M/P, mainly because I have a very large moment versus the axial load ( M = 24 k-ft, P = 5 kips). I'm trying to find some design examples of a flagpole base where the lateral forces are acted on against by the lateral soil pressures. I want to keep my foundation economic and easy to build as possible because this is a recreational structure only 20' by 20' in dimension. I was thinking of a 3' x 3' x 2.5' footing or so..Any help would greatly be appreciated.
Glenn

 

[72shortbox]

you can use the sheet pile wall method described by Das
Its acceptable to use 2-3 times the shaft diameter when determining the passive resistance when using piers instead of a continous sheet.