pole buildings 1

[rittz]

For lateral bracing of a pole building (say 100 x 200 x 16 ft high)do you employ kneebraces or design roof as as a diaphragm and end walls as sheer walls. I'm not fussy about the latter when the client wants only roof strapping and light gage metal covering.

 

[Ron]

Knee braces.

 

[MiketheEngineer]

I use the walls as shear walls. Knee braces have their place but are hard to install and connect adequately.

If it is truly a pole building with the columns about 4'or more in the ground - look at those as cantilvered beams. They may add a lot of help.

 

[RockEngineer]

For design you may want to look at and download "Pole Building Design" by Patterson, from this page of slideruleera's website. There are a number of posts on eng-tips on this subject.

http://www.slideruleera.net/miscellaneous.html

 

[MiketheEngineer]

Patterson goes back to 1970's or further. There have been many innovations and changes since then. Check out Woeste at Virgina Tech. He is one the best guys in the industry

Or go to NFBA.com or org... National Frame buliders - they have lots of info.

 

[msquared48]

I don't think you will get enough capacity with light gage metal deck for the roof diapphragm and strapping at the side walls for building that size - the forces will be too great for both. Personally, I think the client is kidding himself without the use of plywood at the roof and shearwalls.

Mike McCann
MMC Engineering

 

[MiketheEngineer]

I agree with msquared --- THAT is a very large pole building!!! ut I have done them.

Can you put in some interior wall sections - say every 60' or so?? They dont' need to be 100' wide - so you can have a large opening between bays.. Those can be used as shear walls and actually breaks the building into about three segments??

Need more info for a real good answer...

 

[RockEngineer]

I purchased the NFBA books several years ago and haven't used them much. The biggest drawback I saw to their method was that you were required to get shear wall and diaphram data from the metal siding manufacturer for your particular brand of siding including testing for all the different attachment schedules. I didn't find much data out there from metal siding manufacturers that provided all the information you had to have to count the metal siding and roofing at all for diaphragms and shear walls. Something may have changed or maybe I just didn't look hard enough. Those I did see seemed like it would take a lot of field inspection to ensure it was installed as required to be able to use the manufacturers instructions. Most people hiring me to engineer a pole barn or horse arena weren't willing to pay for lots of hours of special inspections. The people doing the construction weren't always willing to follow detailed engineering instructions.

I agree with msquared48 that a pole building this size will be hard to engineer without plywood roof diaphrams and plywood shear walls. Using Peterson's pole building methods will require very large treated wood columns buried 6 feet or more deep in minimum 2 ft diameter holes filled with concrete or compacted gravel.

 

[MiketheEngineer]

Check out Fabral

 

[WallenEngineering]

We just finished a design of a large pole building. We decided on large (larger than usual) posts set in concrete footings, with knee beaces and trusses designed to handle forces induced from the braces. We specified connections of the braces, concrete, columns ect. We had a few special details, but nothing the builder could not easily handle. Most were more nails than he would normally use, but nothing too fantastic. I don't know how you get around special inspections or fstening details. When the building has no considerable structure systematically built in(the lack of sheathing and interior walls), the elements that are left(trusses, posts, and braces) are all there is. If there is an engineered solution, the forces need to be transferred somehow. These require detailed connections, and components. The 2' embedded columns you mention, do not seem far off. Try developing a fixed connection at the tops of the columns as well, by fastening to the sides of the trusses, and deep beams for the other direction. This may help the footing depth issue. My experience is that the diameter is often governed by uplift, and soil bearing capacity anyway. Posts alone usually do not cut it for bearing if there is any kind of snow load to speak of. Good luck!