Replacing A Steel Composite Beam 3

[L_D_]

Does anyone know of a method for replacing a corroded steel beam that is composite with the concrete slab above? Is it possible to cut the existing beam out when it's attached with dozens of headed studs? If that could be accomplished, can you retrofit anchor the new beam to the existing concrete to achieve composite action again? Or just design the new beam as a non-composite beam if space allows? Alternatively, could the slab above be broken out locally to the beam and re-poured without the new cold joints diminishing the capacity of the slab? Thanks in advance!

 

[dik]

Does the new beam have to be composite?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JAE]

You could do the following:
1. Install a new beam adjacent to the corroded beam, or two new beams on each side.
2. Set new beams tight to the underside of the slab.
3. Decided if you absolutely must make the new beams composite. This may not be necessary and may be desirable to avoid higher costs.
4. If composite, you can core down from above through the slab to the top of the new beam(s) and install studs from above. Cores would have to be large enough to allow for the welding gun access.
5. Fill the cores with non-shrink grout.
6. If appropriate, cut away the old corroded beam - possibly leaving the top flange in place. Or just leave the old beam there if that works for you.

Note that the new beams, if composite, won't behave like the original beams which were spanning with the dead weight of the wet concrete before hardening/composite action took over.
But the ultimate strength of the composite beam would be unaffected by that.

If you don't do the coring/composite studs then the new beams could be fabricated with top flange holes to allow some nominal fastening (concrete screws, etc) to at least provide some positive attachment to the slab for lateral bracing purposes.

 

[dik]

JAE... your procedures are great.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[HouseBoy]

JAE -
Instead of welding studs, could one use bolts with a nut above and below the flange?

Alternatively to that.... (if say, the top is not accessible) Could anchors be installed from below?

L_D_
Any reason that they can not shore the existing beam prior to installation of the new beams?

What part of the existing beam is corroded? IF it is at the concrete interface, I'm wondering if corrosion will continue (and cause problems with separation or something like that).

 

[JAE]

I suppose you could use bolts/nuts but stud welding from above is much quicker with less labor I'd think.