Opening in Awning Beam

[KutEng]

We have an awning beam as part of a frame supporting 12mm thick glass that needs a 100mm diam hole cut in it directly below an anchor bolt to allow a stormwater pipe to pass through. My first thought is to check the section capacity with the reduced member depth at the opening, however, I am certain there is more that needs to be considered before giving this the OK.
Before even doing any calculations I have a feeling it will be fine as the direct bearing of the top flange on the underside of the slab is probably acting as more of a support than the anchor bolt itself since that section beneath the slab will be in uplift.

Note: only the awning beam highlighted in plan needs an opening cut. The rest will remain as designed.

Any advice or a point in the right direction would be appreciated

 

[Ron]

Weld a pipe nipple or coupling through the beam web and connect the drain to it.

 

[phamENG]

If you can't do what Ron suggested, look up AISC Design Guide 2, Design of Steel and Composite Beams with Web Openings. (The cover shows a graphic of a composite beam, but it covers non-composite in detail as well.)

 

[hokie66]

Ar Engineer,

Wind load on the awning will create a load case of upward loading, therefore placing those little anchors in tension.

 

[JLNJ]

I would be more concerned about the shear/prying in those horizontal anchors. They look like they want to rip right out of the slab.

As far as the drain goes, talk your mechanical guy into the smallest hole possible and check it with the AISC DG. Note that your case will have max shear and max moment. Most beams either have one or the other or a lesser combination when both are present. Your cantilever is a little different animal.

 

[Craig_H]

Blodgett's Design of Welded Structures also provides guidance on web openings in girders, which may be of assistance to you. I have not personally used the AISC Design Guide 2, so I cannot comment on the relative usefulness of that vs. Blodgett. I will say that the proximity to the anchor may pose a challenge, especially in an upward-applied wind load scenario as mentioned by hokie66.

 

[msquared48]

Depending on the section you are cutting through, just weld web stiffeners on each side of the penetration.

Ron’s option is best though if possible.

Mike McCann, PE, SE (WA, HI)

 

[KootK]

Before even doing any calculations I have a feeling it will be fine as the direct bearing of the top flange on the underside of the slab is probably acting as more of a support than the anchor bolt itself since that section beneath the slab will be in uplift.

I largely agree with your assessment as shown below. If it were me, and the original design of the outriggers was kosher, I'd be willing to okay this on inspection without calcs.

 

[KutEng]

Thanks everyone for the advice. Unfortunately, I do not have access to the AISC design guide (Based in the land down under) - is there any way I can access an excerpt from the guide? Or is there enough value in the guide to justify purchasing the guide? (we deal with web openings maybe 3 times a year and usually just surround the opening with stiffeners and call it a day)

Weld a pipe nipple or coupling through the beam web and connect the drain to it.

I have no experience with how this would work theoretically. Can someone care to elaborate?
I'm thinking the pipe nipple either:

a) has a smaller diameter than the pipe to reduce the opening size, however, I imagine this would cause too many issues for stormwater
OR
b) acts to transfer the internal forces around the opening thus essentially mitigating the effects the opening would have?

 

[dold]

I know some people are funny about posting links to free versions of pdfs. But if you google "aisc design guide 2", the fourth link down might have what you're looking for. Order might be different for you than it is for me though. The domain is abarsazeha.com...

 

[Agent666]

Ar Engineer, use the SCI guide P355 from the UK which is available free here (all their guides are free after they spend a while as paid content).

Or alternatively the new composite standard AS/NZS 2327:2017 now has the SCI guidance more or less codified in it (refer to appendix C). The SCI guidance is pretty much the state of the art method now days, far more advanced than the AISC guidance. Given NZ/Australia now have the new composite standard which more or less borrows heavily from Eurocodes, you're better off using the SCI guidance for compliance.