40'X60' pole barn questions

[jimtheengineer10]

A potential client asked me if I could draw up some plans for his pole barn.

This is how he would like to construct it:
20' tall p.t. 6x6 columns spaced 8' apart with 4' in ground
2x4 strapping at 24" o.c. for walls and roof.
1" vertical pine board siding on walls
Metal roof
A 2x12 at the top of each column on each side (one on each side bolted to column)
A 2x10 sitting flat on top of 2x12's and column
He will have diagonal braces near the top of the column (making a Y shape basically)

Area ground snow load is 55 pdf and the Wind Speed is 115 mph.

Will this work or will he need to put full plywood sheathing on the roof?

 

[JAE]

We could never get "pole barns" to work. All the regional pole barn companies typically put these up in agricultural areas where there is no code enforcement.
When they have a client that needs one "in town" and ask us to review/stamp the drawings - we can not get a lot of things to meet code provisions.

For your case, I would think a plywood diaphragm would be needed but that would be something you'd have to verify with a full design effort on "their" system.



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[jayrod12]

I've gotten a few of these to calc out. But it wasn't easy, and wasn't cheap for the client. All of the money they "saved" on the building, they spent in fees for us to get the AHJ to buy in.

The ones I've seen are generally built-up 2x8 columns at 4 ft o/c. I doubt you'll get wood trusses to work at 8ft spacing. I also doubt that 2x4 strapping will span 8ft.

There's a Post-frame building manual put together by the National Frame Builders Association. Check that out as a good starting point.

 

[XR250]

I doubt the lateral stability will check out on that without using metal siding or equiv. as shearwalls. No way "Y" braces on a 20' 6x6 is gonna work.
I usually run away from these as JAE has expressed.

 

[msquared48]

You will probably have to use plywood shear walls and roof diaphragm with a 40x60 structure, as well as extend the pole footing to a sufficient bearing value for the snow load.

Should be able to be done, but definitely not an off the shelf structure.

Mike McCann, PE, SE (WA)

 

[dik]

I don't know if this helps...

Dik

 

[msquared48]

There is no way 20 foot 6x6 wood columns will work laterally. Maybe steel, maybe...

Mike McCann, PE, SE (WA)