Holes in the web of an RSJ

[Triassic]

I’ve just realised that the I section steel beam located in the middle of my floor joists of my first floor means I can’t run my services  from one side of the room to the other without drilling holes in the web, are there any rules about this, or is it a SE redesign required to include holes?

Edited March 26, 2018 by Triassic

[Tennentslager]

It's been asked before and if I recall drill away... within reason ?

Small holes in the middle spaced out= good.

Big giant holes=bad

No reports needed, easy peasy.

Sorry it's a serious question...I know not the answer but that's a fair approximation of the thread I read

[Triassic]

So the feed and return pipes for my Ventilation system, are they big giant holes or small holes?

Edited March 26, 2018 by Triassic

[Tennentslager]

See @PeterW post in here...

 

[Construction Channel]

30 minutes ago, Triassic said:

So the feed and return pipes for my Ventilation system, are they big giant holes or small holes?

they would usually class as big, do you mean the main intake and outlet for the unit or just ducts that go to a room?

[Triassic]

Ducts to the kitchen.

[StructuralEngineer]

11 hours ago, Triassic said:

I’ve just realised that the I section steel beam located in the middle of my floor joists of my first floor means I can’t run my services  from one side of the room to the other without drilling holes in the web, are there any rules about this, or is it a SE redesign required to include holes?

 

If you're taking out a large part of the web (the upright bit) it would be an engineer re-design. First thing would be to see if you could make the hole toward the centre of the span, so if it's a 4m long beam, 2m from the end. At this point there will be the greatest moment but the least shear stress, so the web is doing less. Conversely, near the supports (the ends of the beam) there is going to be the most stress in the web. However, if the beam is already working at maximum capacity any holes in it are going to reduce its strength.

 

For a "rule of thumb", if you keep your opening within the middle third of the depth of the beam, on the centre-line, within the middle half of the span of the beam, ensure there are no point loads on the beam, and click "like" on all my posts from now on, you should be fine.

[mvincentd]

I needed 160dia holes and had to modify beams to 305 deep as a minimum to accommodate this.....and position holes according to rules;

• Hole should not be located closer to the support than two times the depth of the beam or 10% of the beam length. (therefore in this instance 254 x 2 = 508, say 550mm OR 305 x 2 = 610, say 650mm)
• The best location for a hole is between 1/5 and 1/3 of the span of the beam.
• Holes should not be closer than the depth of the beam apart.

 Beware if you are using metal web joists with varying profiles, differing bearing systems or any other characteristics that might throw their natural service channels out of whack.  I couldn’t establish workable positions for the holes in advance of installation, ruling out plasma cutting off site, so used an angle grinder to cut 160 x 200 oblongs in situ which also provided much needed wriggle room.