Jack stud to king stud connection 1

[Daniel.858]

I designed a LVL to support the roof/ceiling loads from an interior wall that is to be removed. A single 2x4 jack stud will not handle the load. I want to connect the jack studs to the king studs and try to transfer some of the load to the king stud. Can I design the fasteners for half the load and design the post as a double 2x post?

 

[jayrod12]

I'm typically of the opinion that yes provided there is enough fastening between the plies.

That being said, LVL in bearing is normally pretty terrible, so if you need more than a single jack for load, you likely need more than a single jack for bearing length.

 

[XR250]

That being said, LVL in bearing is normally pretty terrible, so if you need more than a single jack for load, you likely need more than a single jack for bearing length.

I thought LVL's were around 900 psi - way more than the axial capacity of a typical 2x4 stud (900 x 3.5x1.5 = 4725 lbs)

 

[Tmoose]

I believe a few thousand words, or a couple of pictures, would help to clarify if the new LVL beam is bearing on 2X studs, or some curious LVL "studs" are being ordered along with the LVL beam.

 

[dik]

Use two jack studs? It would take an awful lot of nails to transfer a load from a jack stud to a king stud.

Dik

 

[KootK]

Is strong axis buckling the failure mode that you're looking to address? If so, you can utilize both studs without transferring axial load from the jack stud to the king. All the fasteners need to do is ensure that the two studs travel laterally in unison under a hypothetical buckling scenario. There are a few ways to skin that cat analytically but, in the interest of keeping things simple, my recommendation would be to ensure that you've got enough lamination nailing in the middle third of the stud group height to laterally transfer 2% of the total axial load on the stud group from the jack stud to the king stud. Then design the stud group using the composite EI values for the Euler buckling stress. My money says that you default lamination nailing is plenty.

Naturally, if bearing or in plane stud buckling are issues of concern here, then additional attention would need to be paid to those things as others have noted.

While it's pretty easy to get the studs to participate in joint buckling, as I've described, it would probably be quite difficult to get them to meaningfully share axial load in the manner that you seem to be targeting. Doing so would require:

1) Getting the load transferred over a relatively short segment of the stud group near to the point of load application.

2) Transferring the load with a minimum of joint slip.

Both of those things are tough to do with nails.

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.

 

[Daniel.858]

Thanks for all the advice. I think I'm going to call out double jack studs, because there is a lot of load being supported by the beam.

 

[KootK]

Good call.

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.

 

[jayrod12]

I thought LVL's were around 900 psi - way more than the axial capacity of a typical 2x4 stud (900 x 3.5x1.5 = 4725 lbs)

I used to think it was no problem as well, until I started using Forte to size my LVL beams and found more bearing failures than I expected. Especially when compared to the old TJBeam software we once used.

 

[dik]

OP: Good choice... easy and inexpensive.

Dik

 

[dhengr]

Jayrod12:
Did you call all of your previous clients and tell them that recently, the code writing authorities, the formula formulators and the software reinventors and hustlers had declared that all earlier buildings had failed?

 

[XR250]

I used to think it was no problem as well, until I started using Forte to size my LVL beams and found more bearing failures than I expected. Especially when compared to the old TJBeam software we once used.

I think the bearing failure you may be seeing is the supporting wood top plate which is typically around 400-500 psi. I have never been in a situation where the bearing stress on the LVL was a limiting state.

 

[jayrod12]

Quite possible XR.

And to dhengr, I'll get right on that. Anyone have a convenient way to contact 100's of previous clients.

Really in the end, bearing failure is not a life-safety issue in my eyes. It's a small amount of crushing but that is manageable.

 

[KootK]

Anyone have a convenient way to contact 100's of previous clients

Media blitz. Full page ads in newspapers and on social media proclaiming your utter incompetence. At least, that's what I do.

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.

 

[jayrod12]