Splice steel column near base plate

[kodstruct]

Hi,

The contractor is having an issue on a project that I engineered and submitted an RFI.
Basically, he set the top of pier 6" lower than what is in the construction documents. Now the columns that the steel company shipped to the site are all 6" shorter.
They are asking if they can splice a piece of column to make up for the length. For me 6" doesn't meet the space/length for splicing. Any thought?
I was thinking about double plate splice with bolts. In other words, keep the base plate of the short columns, provide a plate at the top of the little stub column, bolt everything together.

Thanks.

 

[KootK]

What kind of column section is it? Wide flange? HSS? Purely axial load? Do you mind if there's a bunch of ugly stiff protruding 6" above the real base plate? Depending on your situation, there are a number of alternatives:

1) Cut off the existing base plate and full pen weld on a new stub column / base plate assembly.

2) Do the same as #1 but make it bolted or fillet welded to the column somehow.

3) Extend your anchor bolts and make up difference in either grout or shim plates.

4) Leave the existing base plate on and bolt it to a column stub extension below that has both a base plate and a cap plate.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SlideRuleEra]

... or a fifth alternative:
5) Contractor purchases new columns that are 6" longer.

actually, IMHO, Option 1) is the best compromise.

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[kodstruct]

It is a W flange.
Pen welds will do but I have the feeling that the contractor would prefer bolting the exiting column base plate to a cap plate of the little stub column.

 

[KootK]

No doubt. I imagine that the existing base plate bolt holes are oversized. I'd ensure that they get pretensioned for good measure. Your reconstituted column may also need to work as a cantilever for OSHA loads in the temporary state.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[kodstruct]

You nailed it..... That's a great point. My response will be pen welds, take or live it. I don't think the contractor has ever used pre-tensioned bolts...

 

[KootK]

I commend your willingness to be open to suggestions from the field. In that vein, you could also:

1) Upsize your bolts to suit the oversized holes and have those holes reamed if necessary.

2) If you can tolerate leaving the existing base plate in place, you could fillet weld the new stub to the underside of it. That should be cheaper than full pen both in terms of fabrication and inspection. Besides, in the field, you might be better off with fillet weldS anyhow. A good full pen field weld takes some skill. At least that's what I'm told. I just draw pictures and Google stuff.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.