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RE: allowable hole in wide flanged beam

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I worked for the Navy for a number of years.  EVERY beam had holes to lighten them.  Most "Land" Structural Engineers seem to have a fit about putting holes in a beam.    I have to chuckle given the quantity we used and the loads those beams saw.  It's not that big of a deal IF you put them in the right place.  I don't have any references for you but here are a couple of rules of thumb.  Basically, you are taking advantage of the neutral axis by removing material in the area of VERY low stress.
 
1) Holes are BAD in shear zones.  Hence, never put them in bearing areas and under concentrated loads.
2) Rule of thirds:  If you keep them in the middle third, both ways, you are ok.
3) Limit the diameter of the hole to 1/2 the beam depth. 
4) Keep the hole circular or semi-circular (hexes and octagons).  I've seen ovals for ducts but I would always calc these.
5) Space the holes 1.5 - 2 times the diameter.
6) Smooth the edges.  If you field cut, which I don't recommend, make sure they grind the hole smooth not just remove the burrs.
 
If we were concerned about a particular hole, then we would draw the shear and moment diagrams (remember those?) for the beam, then check the reduced section at the point of the hole.  Computing the reduced section should be easy if you keep the hole centered and it's not that hard if you keep it in the web. 
 
Holes in the flanges are a completely different story as Jason pointed out.
 
Mark Jones
Jacobs Engineering
Structural Engineer, formerly a Naval Architect.
-----Original Message-----
From: Pat Clark [mailto:bcinc(--nospam--at)nanosecond.com]
Sent: Wednesday, April 04, 2001 4:31 PM
To: seaint(--nospam--at)seaint.org
Subject: allowable hole in wide flanged beam

What kind of references are available for designing holes through the web of a wide flange beams.  Should I just check a reduced section, and moment of inertia?  Is there any code references? Any help would be appreciated.
 
Pat Clark, P.E.