Web Holes in Steel Beams

[531234]

I am designing a simple 5.4m span steel beam that supports three concentrated loads. The client wants to put twelve circular holes with a diameter ranging from 2" to maximum 4". I am using CISC 9th edition as my reference and according to my analysis using W610x140 is good. The concentrated loads are 282 kN, 570 kN and 600kn with a distance from the left support of 0.5m, 2.4m and 4.4m respectively (loads are factored). Again, the beam is okay after following the design guidelines in the CISC. However my concern is according to CISC, concentrated loads directly above hole locations should be avoided or be at least 'd' (beam depth) from either end of a hole. Some of the holes will violate this requirement. Should I have to worry about these holes which I think are relatively small compare with the depth of the beam?

 

[rb1957]

maybe it's obvious to you structural types, but how deep is your beam?

if you think the web can handle the loads and the cut-outs then go for it.

if you prefer to follow the guidence, ask for them to be nudged out of the way.
or is there a pressing reason putting the holes where they are (in which case you have to suck it up) ?

if the loads are truly point loads, do you have a stiffener running down the web, supporting the web, distributing the load ?

Quando Omni Flunkus Moritati

 

[531234]

The beam is 617mm (24.3") deep. I am planning to add horizontal stiffeners top and bottom of the holes although the design pass unreinforced holes. The concentrated loads are secondary beam framing on to the principal beam (W610x140). The holes will not be directly on the holes but roughly 6" to 24" from the holes.

 

[rb1957]

"The holes will not be directly on the holes ... " ? (it looks like you type the way i do ... looking at the keyboard)

s/b "The loads will not be directly on the holes" ?

sure, reinforce the holes, but i'd put web stiffeners under the point loads before horizontal stiffeners reinforcing the web holes.

Quando Omni Flunkus Moritati

 

[BAretired]

I don't think you should have any problem with that if the holes are within the middle third of the beam.

BA

 

[hokie66]

Agree with BA. Those size holes, located at or near middepth, are inconsequential.

 

[531234]

Thanks for all your replies.

 

[Ozy101]

I have done a bit of work on cells and cut outs of steel beams and as mentioned that its best practise to endusre you are a minimum of D away from an opening but for a small hole (11cm max on a 54cm deep web gives you a steel ration of 0.2) I woulnd tbe all the worried. However I would still do a quick check on the top and bottom ts to ensure that they cant take the stress. How far away is you next hole?

 

[SethGuthrie]

Ram SBeam (or the full Ram Structural System) can design beams with web openings per AISC, CAN S16 BS 5950 Eurocode and AS 4100 including the design of the stiffener plates if you are interested.

http://communities.bentley.com/prod...4956.aspx?skid=CT_EML_NA_STRNL_JUNE2011&MIG=X

 

[531234]

Thanks SethGuthrie,
Holes are spaced 1l inches center to center.

 

[SethGuthrie]

For tight, regularly spaced wholes we often refer to them as castellated beams. There are companies in the US and UK that make them. CSC in the US actually provides a free copy of Ram SBeam to help with the design in fact. I think Westok might do similar.

 

[homostructural]

I searched through internet and I found this thread about cellular beams. You might find it useful!

All about Eurocodes:

http://www.DesignToEurocodes.com