Bolt Through Pipe Column

[BadgerPE]

Hey all,

I am looking at an existing building in which a new awning has already been constructed without the approval of the city. My job is to somehow make this work w/o taking it down if at all possible. On the upper ledger, I can through-bolt it to multiple 2x6s sandwiched between channel sections. However for the lower ledger, the only solid thing in the wall section is a pair of 6" Dia (thickness unknown) pipe columns. These columns will have to support a small amount of gravity load as well as about 1k of lateral load induced by the uplift on the awning. I should add that these columns have some sort of circular architecture near the top, but not where I was looking at bolting through.

My question becomes, is there any place to find an example of something like this or a specification that says it is allowable to bolt through a round column? My intuition says that this is not a good idea, but I am struggling to find a solution to the problem.

On a lesser note, the snow loads are kicking my tail on this one. Based upon 7-05 ground snow load is 30 psf, balanced is 23 psf and the drift load is 71psf tapering to 47psf. The drift load is based upon an upper roof length of 130' which slopes away from the awning. The awning projects 5.5' from the building and has a 6/12 pitch. I am having a hard time justifying these high snow loads because the upper roof is 20' above the awning and has an estimated 3' parapet around it. Is there any literature which would allow for some snow load reduction due to the height above the awning or the parapet blocking the wind-blown snow from reaching the awning?

Thanks much for any help in advance!

 

[a2mfk]

Man you got handed a pile of you know what on this one!

I know your detail is a rough sketch, but it appears to me you are going to be counting on some cantilever action from those bolts? I would personally avoid that, not sure if AISC allows that.

Can you remove the decorative arch cover at the top? Then maybe shim out that space with a HSS tube member and connect to the pipe with through bolts. Still tricky but maybe easier to resolve all the forces.

I live in FL and have very little snow experience, but doesn't a sloped roof give you some discount for sliding? And I thought an upper parapet did offer you a discount from drifting effects from that upper roof.

Good luck with this one...

 

[msquared48]

I am concerned with both connections...

The one at the top I would like to see attached to a roof or floor diaphragm if possible. I question channels in weak axis bending between the pipe columns, but it could work.

At the lower one I would bend some 1/4" plate around the outside of the pipe columns and weld them to it, extending the tabs of the plate forward to catch the awning.

As for the snow load, the loads you mention are not unreasonable for a 30 psf ground snow, but I agree with a reduction due to the parapet above to catch any sliding snow.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[SlideRuleEra]

For the connection to the pipe columns, perhaps you can adapt a pipe clamp. These are typically used for industrial pipelines and are rated for fairly substantial loads:

http://www.cooperbline.com/pdf/catalogs/PH08/Clamps.pdf

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[BAretired]

The columns have an eccentric load from the snow and awning weight. The top of each column must be laterally braced to prevent it from collapsing outward unless you are relying on base fixity.

The upper beam must be capable of taking the vertical and horizontal load from the awning. It doesn't appear very hefty.

The awning must be capable of transferring its horizontal reaction at only two points, i.e. the two column locations. If it was not designed for that, you will have to add a member to carry the horizontal load between columns.

It may be possible to bolt through the round columns. You would find out the wall thickness if nothing else. But it is probably simpler to introduce an exterior bracket as suggested by Mike.

BA