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large hole in steel I-beam

large hole in steel I-beam

large hole in steel I-beam

Hello fellow Structural Engineers,

I am supporting a floor with 100 psf Live Load with a 16" steel beam. However, I have been asked to have a 13" diameter hole.  What design guide is available to check such a larger hole in a steel beam?

I can deepen the beam to as much as 24" but I am looking to minimize the depth.

Thank you for your help!
I appreciate it.

RE: large hole in steel I-beam

There is am AISC design guide that deals with web holes (from memory it is design guide no. 2). A 13" diameter hole in a 16" beam will be too much in my opinion. I remember reading in a steel code somewhere that any opening greater than 0.3*D requires longitudinal stiffeners. I will upload some info when I get home.

RE: large hole in steel I-beam

So like I was saying, the AISC design guide you need to obtain is Design Guide 2: Steel and Composite Beams with Web Openings.

AS4100 (Australia Steel Code) says:

Except for a castellated member, an opening in a web may be unstiffened provided that the greatest internal dimension of the opening (lw) satisfies either-

(a) lw/d<=0.1 for webs with longitudinal stiffeners; or
(b) lw/d<=0.33 for longitudinally stiffened webs,

provided that the longitudinal distance between boundaries of adjacent openings is at least three times the greatest internal dimension of the opening.

In addition, not more than one unstiffened opening shall be provided at any cross-section unless a rational analysis shows that stiffeners are not necessary.

The design of a castellated member or a member with stiffened openings shall be based on a rational analysis.

I had a client who asked me to provide holes in the webs of a member so that they could pass through pipes. The dimension of the opening was very small and I located the openings in low stress regions and provided longitudinal stiffeners anyway.

thread507-187710: Web Holes

RE: large hole in steel I-beam

For that big a hole I would stop the I beam on each side and figure out some type of way to connect the two.

RE: large hole in steel I-beam

Where is the hole, midspan or near the support?  Since it is a circular hole, I like the idea of reinforcing with a RHS (Round Hollow Section) fillet welded to the web all around, but you may have to increase the depth of beam by a couple of inches to make room for it.


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