Notched Column Reinforcing 5

Are you doing this work before it's erected or after erection? I'm assuming it's an existing structure right?

What design actions are being carried here as it has some bearing on an appropriate the solution. I ask because you detail compromises the column for axial buckling and probably for flexural torsional buckling when the notched side of the column is in compression. Your solution does not really address this aspect of the behaviour in my view, can you provide a printout of the axial/moment envelopes?

My proposal sketch is below. If this work will be done on erected structure, shoring of the system be necessary with scaffolding, props , etc.

The transfer section slope should be in the range of 1H: 5V, and use web stiffeners ...

I must add that,for me, it is not reasonable fault and i did not like my proposal also...

However you choose to solve this problem, be sure that you have a welder go back and make all the single sided welds (web to flange welds on the 3 plate beam-column) a double sided weld in the reinforced region with appropriate start and stop lengths. You must make sure the 3 plate column is adequately reinforced.

Jim

OP said:

My question is what is the best way to transmit the flange force from the existing flange into the double angles?

Click to expand...

In my opinion, it would be more conventional to simplify it to something like this which would probably tilt things in the direction of flat plates rather than angles.

OP said:

I am considering some gussets running diagonally from the flange to the reinforcing angles as shown below. Does this sound like a reasonable approach? Is it even required?

Click to expand...

I would say that it's not required as the web itself can usually be used to adequately transfer the flange forces laterally via web shear.

Hturkak: I like your reinforcing better terminating the stiffeners about 1-1/2" inside the outer flange. Inner flange is likely in fairly high compression.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

A slight change from HTURKAK's solution. Watch out stresses in the web panels, especially the one with odd shape. .

waytsh - When you say "I can easily get the reduced section to work" how are you analyzing the new section, are you using the original design loads?

I don't know the effects of modifying the leg of the PEMB, but there could be a shift in the reactions from the original... not sure how much. I did mods to a PEMB several decades back where the frame had a single supporting column at mid span and the owner wanted to remove a leg at the haunch to create a large opening... there was a huge change in moments as well as reactions that had to be addressed.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Yeah, PEMB is not very kind to changes. A slight alteration can result in a lot of strengthening works.

and you may want to leave 1/2" or 1" of clearance between the concrete and the leg... to prevent 'hammering' of the steel against the concrete during wind... you realise that these modifications likely void any warranty.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Thank you for all the replies, they are much appreciated. The columns have been erected already and are in place. The column will be subject to axial, bending, and shear at this location. I can't generate diagrams but the base is pinned so moment will be tapering to zero at the base with shear and axial load being relatively uniform. If I consider the worst case of these three simultaneously, use the lower yield of the angles for the entire section, and use the smallest section at the lowest portion of the column, it is at about 60% utilization.

The solutions HTURKAK and r13 have suggested is the approach I would normally take. However, this approach is very labor intensive with the butt welds and fit up of the plates. I was thinking with the angles we could avoid much of that work and it could be largely installed prior to cutting out the flange. I am fond of KootK's detail with just a slight modification. If I stubbornly hang onto the angles and trim back the inner gusset what are your thoughts on this configuration?

That's why you leave a 1-1/2" gap on the outside of the flange.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Watch out stresses on the upper cutout. I like to avoid 90° corner in metal.

I assume you have already checked the global strength of the column considering it's reduced section modulus?

If so, the only issue is local strength, particularly at the re-entrant corners.

“Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands.”

Dear waytsh , i did not mention the use of new flange plates. If i were in your shoes, i will check the existing flange thickness for reduced section . If OK, just take out the web portion (red painted ) with oxygen burning then cut the flange at ( A ) and bend flange at B and C to fit new situation and add web stiffeners . With this set up, you only need one butt weld , others will be fillet welding.

hturkak: I thought that's the way it would be done... and stiffeners the only added component.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik