evaluation of damaged steel columns 1

[tpmanzi]

I have a W8x28 column with a 3" slotted hole in the web from a forklift - is there reason for concern? It is being used as a 17 ft column and is axially loaded to 100% of it capacity.

Also hav another column with flanges bent out of plane by as much as 2" over a 4 ft length. Comments??

 

[htfptm]

Sonotube, concrete, yellow paint.

While you are installing them on the damaged columns, you can put some on the ones that haven't been hit...yet.

 

[SteelPE]

Depending on the height of the damage, the fix proposed by htfptm is pretty standard. As he suggests, your client may want to provide some means of column protection or something drastic may happen. See attached:

http://www.eng-tips.com/viewthread.cfm?qid=215858&page=5

 

[SteelPE]

Oh, and the repair in the picture was a new column (if I remember correctly). Others damaged in the building received the sonotube, concrete repair.

 

[paddingtongreen]

My guess is that the slot will make no difference. The bent flanges sound as though they would be more likely to buckle, just how are they bent, is the bend in the web or just one side of the column? a sketch would be useful.


Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[csd72]

If it is axially loaded to 100% of the original capacity then it is now overstressed according to code (even if only by a few percent). I would definately suggest some type of strengthening measure.

The sonotubes are the best idea if the client is okay with them. They will both strengthen and protect the column.

If that is not an option then I would suggest a welded cover plate over the region of damage.

 

[Lion06]

I would be less concerned about the hole in the web - assuming the column isn't bent. How far from the bottom is the hole and how tall is the column? If it's very close to the bottom, I think there's a good case for using a higher allowable compression stress.

I would be a lot more concerned about the column with the bent flange. In my mind, that's almost like initiating a local buckling failure.

 

[Ron]

Agree with the others...straighten the bent flanges then encase the columns in concrete. Yellow paint is good!

 

[paddingtongreen]

I suggest the slot is not a problem because the allowable stress is a false way of applying a buckling load limit. Locally, the material is still of the original strength. If you run an analysis of the column, by program or one of the iterative methods that have been discussed (Newmark?) on here, you will find virtually no difference in buckling load.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[rscassar]

1. Judging but the recent post which SteelPE has attached, I believe it would be best to provide protection to the columns as has been suggested. The photographs also provides evidence that there is a threat from a column being taken out from accidental impact.

2. If the column has a pre-existing deflection of 2" and the column is loaded to 100% of it's capacity than I would think there is call for concern from the P-delta effects. Have the additional stresses from this deformation been considered in any analysis.

Have I interpreted your problem correct assuming the column appears warped 2" or is it just local damage to the flanges from accidental impact?

 

[weab]

My 2 cents. Generally I agree with others. You say the column is loaded to 100%. Would seismic add significant load to this column? Any chance that some cowboy might load it beyond capacity?

Slot in the web is probably not a problem, but I couldn't justify not fixing a known problem. Flange seems like the larger problem.