Reinforced beam with web penetrations?

[SteelPE]

I have an existing beam that need to be reinforced and need two 9” dia holes drilled in the web (on opposite sides of the beam). The reinforcing is due to the owner adding more load onto the beam.

I am considering welding a plate to the underside of the beam however, I am not sure how this will effect the calculation for the web penetration. I have gone through DG#2 from the AISC and am wondering if I can treat the bottom flange of the beam (where I plan to add the plate) as if the beam were composite? Does this seam feasible?

 

[ishvaaag]

Make your assumptions, better in accord with the initial idea, if it was not composite. If I remember well, AISC also treats the composite case, so you are armed for both hypotheses. In any case, with maybe some shoring, the possibilities of reinforcing steel beams are plenty.

 

[jhenry]

Have the beam penetrations be made in the middle third of the beam, if possible. If the penetrations are towards the end, then use a steel flitch plate against the beam web.

Use trasformed sections to deterine the portion of beam stiffness to appotion between concrete and steel, and make sure that the resultant shear carried by the concrete is under phi Vc/2.

 

[SteelPE]

This isn't actually a composite beam. It's a beam that is supporting wood framing. I was wondering how to use the web opening equations to calculate if the penetrations were acceptable.

In the end I went through the composite equations and calculated mu only to realize that I would have been better off setting mu=0 as mu only increase the shear strength of the beam. So I probably would have been better off using the equations for a non-composite beam.