Building frame with severe corrosion in the steel column 2

[ChangeYourIdea]

Hello, I received a call to proceed with a site visit for recommendations on what to do in a building with serious corrosion in the frame column(s) (see pictures), I am not sure yet if it is one column or more than one is in that state). Looking at the pictures, it seems these columns are not carrying many more loads and some buckling signs.

My question is, when we have a situation like this the most common solution is to reinforce the column or replace it? Is replacing a column like this feasible in terms of costs?

I am thinking of right after the site visit, recommend shoring immediately as well.

Any thoughts or suggestions?

What is the line where we should say the building is unstable and should be evacuated?

 

[LittleWheels]

That is not a good look. How quickly can they get that shored?

Are there reasonable alternative load paths for supporting wind loads or (as with most portal frame structures) will a missing column means that part or all of the building will come down like a pack of cards? Propping might not be too helpful in resisting moments.

 

[ANE91]

What is the line where we should say the building is unstable and should be evacuated?

You. You are the line. With all due respect, you should pass this off to someone who knows what they are doing. By the looks of it, lives could be at stake.

 

[JAE]

Agree with the answers above. Get it shored immediately and perhaps keep others away from that whole bay...if not the whole building (don't know the condition of the beam in its span or other columns).

Column is too far gone to repair economically vs. replacement. Shore the beam up, unbolt the bad column and replicate with a new column and bolt back to the beam.

Note that this appears to be a pre-manufactured metal building so the beams and columns are intended to work together as a moment frame. The beam itself can't perform at 100% capacity without the column taking end moments so the shoring should extend the full length of the beam.

Measure up the "bad" column as best as you can and replicate with similar geometry, perhaps a small bit thicker than the original flanges and web.

 

[ChangeYourIdea]

Hello everyone. Thank you for the answers. Yesterday, I went to the location and recommended shoring immediately and not allowing access to this section. This is a building extension of the main building which doesn't present degradation, looking good the main building. This area was used to cut blocks of rocks therefore super humid. In this building addition, there are only 4 columns. In summary, I said right away that the only option is to demolish/rebuild and that I don't recommend any type of reinforcing this damaged structure. Like JAE said to far gone. A contractor was on site and it will shore this structure this week until they decide when demolition will start.

Again, I appreciate the comments.

 

[dik]

Is that a PEMB? If so, there is likely little you can do. Even when new, they are extremely tightly designed (marginal, in my experience).

 

[jayrod12]

We have repaired columns in similar conditions. The repairs consisted of shoring (you've already specified that), shot blasting the column back to bare metal. Installing reinforcing plates in excess of what was there originally, and then pouring a reinforced concrete jacket from ground up above the area where the corrosion is no longer present. We did this repair detail to almost 100% of a building's column recently (the thread about the building is in the failures forum).

 

[HTURKAK]

The tapered columns implies this is a pre-engineered metal building . In my zone , it is typical that PEMB suppliers do skimpty designs and use very thin sections having little rezerve capacity.
The pictures also implies the same. The extent of corrosion most probably more than the visible like cancer.

IMO , this building deserves to be retired. I would prefer to demolish and construct new one.

 

[ChangeYourIdea]

Thank you for the new answers.

The contractor has proposed to do what Jayrod12 just mentioned above. Instead of shoring until demolition (at least 1 year down the road), he proposes to encapsulate the column with concrete up to the beam until the demolition happens. My concern is that once the columns are stable, there is no guarantee that they will be demolished in 1 year. I have some concerns too with the corroded column inside the concrete and how to anchor this new column to the existing foundation and connect it to the beam as well.

Jayrod12, do you have some pictures of your recent project? Did you add dowels to connect this concrete to the existing foundation?

Hturkak, I also would like to retire this structure but sometimes we can find some solution to extend a bit their life cycle.

 

[jayrod12]

Unfortunately I'm not really at liberty to share the photos. But yes, we drilled and epoxied dowels into the caissons that lapped with our concrete jacket reinforcing.

In our case, the columns did not need to resist any lateral load directly, i.e. they weren't part of moment frames the way yours is. So it's not necessarily an apples for apples comparison.

 

[ChangeYourIdea]

Hi Jayrod12, fair enough about the pictures. Not a problem.

Thank you for confirming that you added some dowels. I will need to do a full structural analysis to find a good solution.

I appreciate the feedback of all...