Wood beam and support columns question

[PCustoms]

Framing questions (shop is in the basement, so garage related). Stairs were obviously reconfigured on the fly and there's some less then ideal framing and lally columns (some loose)

House has a 56' beam down the center of the basement made from tripled up 2x10x16' staggered 8' with a lally column about every 8'. For example, first post has the 2 outer 2x of the beam continuous and (I assume) the center has a break. The next post at 16' is where the 2 outer 2x end and the center 2x is continuous. Beam is nailed with no evidence of glue.

How can I calculate the max span?

I've built some walls that can take the load, in hindsight I should have added 2' to one room and hidden the posts. I'm thinking of framing a closet under the stairs, which makes a good opportunity to hide some posts, but this would make my span at 12-14' with 2 joints unsupported.

Maybe a 14' LVL sistered?

Assuming the math works, I could also do the same in the front of the garage (drive out) and eliminate at least 1 lally post.


Potentially compounding the issue, all lally columns were added after the floor was poured and do not appear to have a footing. There is some seasonal movement along the beam.

 

[carlaisle]

Max span is a function of the load on the beam and the beam construction. We have one of those variables. Need a post wherever any part of a beam ends in the application you have described. If you're thinking about LVLs, replacing the existing beam is the correct approach. The load on the main beam needs to rest on the main beam, not near it.

 

[PCustoms]

Max span is a function of the load on the beam and the beam construction. We have one of those variables.

Told you exactly how it's constructed.

The loading is standard residential 1st floor, no roof load is transferred as the roof is trusses.

 

[Hank11]

I think you are trying to remove some of the posts? I’d calculate the load best I could and then figure placement of footings and the new posts. Actually, I’d hire a real engineer to spec this out for me, then follow directions.

 

[jack stand]

I can't tell you how to do the math, but 3ply 2x10 makes a decent beam. I didn't see you mention the length of the floor joists or weather they were on the beam or on hangars.
If they rested on the beam have you considered a good old steel flitch plate?
My "seat of the pants" internet opinion is a 5/16-3/8" x 8-10" 12-16' long "plate" on each side, through bolted or structural screwed would easily give you 16' with no concern without any heavy point loading (bath tub etc) above.
Steel is expensive but in relation to an LVL, by how much?

 

[firebirdparts]

Short answer is don't, really. It just doesn't pass the "who cares" test unless you really need to waltz down there (which is fine if you do).

If you really want to proceed, I might be tempted to do this: Look upstairs for anything load bearing up there. IF THERE IS NOTHING, go by the floor loading, which is easy, and then add an LVL sized to carry the whole load. That is, ignore the original beam due to the unfortunate joint locations.

If there are load bearing items upstairs over this hole, I would punt, but I was going to punt anyway.

 

[PCustoms]

I can't tell you how to do the math, but 3ply 2x10 makes a decent beam.

How decent? Are there span tables?

I didn't see you mention the length of the floor joists or weather they were on the beam or on hangars.
If they rested on the beam have you considered a good old steel flitch plate?

Can't recall the length of the joists, not sure why this is relevant. They do sit on top of the beam, so a flitch plate (or laminated/sistered lvl as I said in OP) is possible.

My "seat of the pants" internet opinion is a 5/16-3/8" x 8-10" 12-16' long "plate" on each side, through bolted or structural screwed would easily give you 16' with no concern without any heavy point loading (bath tub etc) above.
Steel is expensive but in relation to an LVL, by how much?

 

[kwb]

Length of joist tells how much floor loads from above need to be supported.

 

[PCustoms]

Length of joist tells how much floor loads from above need to be supported.

Yep, see it now. Found a few lvl span calcs over lunch.

Still haven't found how to calculate what a triple and overlapped 2x10 can hold

 

[Hank11]

Determination /=/ Engineering.


But you could consider the current beam as doing nothing and go right beside it or replace it with a beam that is properly sized for the job.

 

[firebirdparts]

Still haven't found how to calculate what a triple and overlapped 2x10 can hold

FWIW those were pretty ubiquitous in "ordinary framing" where each side of the house is about 14 feet span (the maximum) with a pine 2 by 10. So these worked with 8 foot spacing on the lolly columns. They're just everywhere. I did not look for what they'd hold because I just don't care that much. Due to the joints, you could consider it mostly like a single 2 by 10, I guess.

 

[PCustoms]

Length of joist tells how much floor loads from above need to be supported.

Looks like 12'