retrofitting a steel post in a basement 2

[SLTA]

ok folks. One story house, wood framed floor, slab on grade. I'm going to have them cut the slab and pour a new footing, and install a new steel post to replace a jack post that has failed by crushing the wood. How do they get the perfect length for the post, and then install it so that it's flush? Without the jack action, I'm worried there would be a gap or it would be impossible to actually install. Thoughts?

 

[SLTA]

Here's a picture of the situation. Not crushing, actually, but 1 ply of the beam was sawcut through and the second has crushed because of it. Is there a better way I could deal with this, without a new post? I'm thinking maybe a sister at the side across the cut, a steel plate across the bottom. and reusing the existing post.

 

[msquared48]

"a steel plate across the bottom. and reusing the existing post" would be your simplest and best option here.

If possible, I would use a couple of side plates welded to the plate too to nail off the to the beam, and a couple of vertical tabs to nail off to the column - something like a Simpson CC hanger sized for the wood members.

Mike McCann
MMC Engineering

 

[SLTA]

brilliant!

 

[SLTA]

Mike, I just reread this. The existing post is a steel jack post. Are you suggesting I can reuse that, or do I need to replace it with wood? If I replace it, I'm basically back to all the issues I had before, if replacing it with steel.

 

[concretemasonry]

As I see the photo, it seems the problem is with the bearing surface that the post has.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[msquared48]

Slta:

Just replace the jack with a wood column - 6X6, 6X8, 8X8 or whatever you need.

Mike McCann
MMC Engineering

 

[dhengr]

Slta:
That looks like a real cobbled mess. Joists over cut at their notches, so they could fit over 2x2 ledger strips; then the double or triple 2x beam partly saw cut through, for some reason, and then cracked off to the right. You’ll have to kinda determine the magnitude of the loads on either side of that saw cut through the beam, and you’ll want to balance those loads over the steel cap system I’m going to suggest and over that existing jack post, repositioned a few inches to the left. You are going to have to do some jacking and temp. shoring to lift everything off the post as it is. I would take a 6" or 8" channel, legs down, for some strength about its weak axis, about 3' or 4' long, from a steel suppliers cut-off pile for least cost; centered under that balance point, and on the axis of the existing 2x beam. Put a few struct. screws through the Cweb and up into the 2x beam, near its ends. I’m not thinking any sort of a moment connection here, just a flat bearing surface, with some bending strength, and some resistance to rotating if your balance point isn’t perfect. Then, use a .5"+ pl., 12" long and just wide enough to fit btwn. the C radii for your repositioned jack post cap pl. over its existing light cap pl. This is just to spread the post load along the length of the channel a bit.

You’ve see this before in some of your old books on timber mill buildings, where they had a large timber column, then a cap timber (corbel timber?) over the column and immediately under the primary beam timber. You might also want to take a look at the IBC or IRC, there is considerable debate about those jack posts meeting code if the pipe walls are too thin, or if the screw jack is not disabled or embedded in the conc. when you are done. And, that the light cap pl. must be nailed off so the post can’t be just pushed over, or unscrewed.

 

[SLTA]

cheers, dhengr, that's essentially what I did for my detail.

boy am I ever glad for this site, to bounce ideas around.

 

[msquared48]

slta:

If you want the steel column instead of wood, just weld a pipe column to a Simpson CC (without the side tabs to the column) .

Mike McCann
MMC Engineering

 

[Splitrings]

Someone must have been seriously drunk when they built that! And short on full length pieces of lumber.