Top Plates 2

[pdev67]

For 20'7" high tall using 20' long studs, Can we make it with 4 top plates connected together with sds screw ? or other options?

 

[skeletron]

Weighing in on the Friday afternoon very general debate:
1. Push for a LVL/LSL stud solution. Go deeper stud too if that is available.
2. 4 top plates is kind of ridiculous IMO. More so for the non-struct problems (shrinkage, thermal, etc). Also probably a more complicated assembly than needs to be there.
3. Not a fan of wall stud splicing in this example. To convince me, I would want an elevation drawing rather than a couple details meant to throw together. I think at that point you would be spending more office time on something that has a better available solution out there (see #1). I know it could theoretically work if you pencil it out, but I get an icky feeling just throwing in a bunch of screws (loosing net section) and then letting Zeus take the wheel...
4. I have used a stud splice detail before, but on smaller section of wall and in temporary case.
5. How are you going to lift/stand the wall? Maybe there is economy in letting that be a solution guide.
6. As an ex-steel guy and currently a Big Steel[sup]TM[/sup] mole in the light-frame wood industry...there's always a solution in steel!

 

[Agent666]

7. Also with timber, you're at the mercy of the contractor and their level of competence and experience and almost more importantly general lack of giving a shit in a manner far more than any other common building material we deal with.

Keep it simple, by the time you bugger round with designing it, drawing it, and waste contractors time splicing it, and waste your time inspecting it. You're better just using LVL in one length in my opinion if a solution exists in that space.

https://engineervsheep.com

 

[ChorasDen]

pdev67, sorry to sidetrack the thread, but it's an interesting discussion.

KootK, I don't have an issue with resolving a concentric axial load with a splice. I don't love it, but I can also easily see a way to justify it. What I don't like is the eccentric load induced from the trusses overtop the wall (probably eliminated if we have 4 top plates) but more importantly, the out of plane wind loads that need resolved over the splice.

You mentioned testing to validate moment-rotation characteristics. Are you able to share a resource that discusses this? I'd be interested in reading more about it.

Wood trusses are a different beast. A nail plated connection is very stiff, allowing adequate load transfer. That differs considerably from dowel type fasteners yielding in shear or local crushing.

 

[XR250]

Seems like two top plates top and bottom sandwiched with 1/2" plywood would be a reasonable solution

 

[KootK]

You mentioned testing to validate moment-rotation characteristics. Are you able to share a resource that discusses this? I'd be interested in reading more about it.

I'm afraid not Choras Den. I didn't say that I had such testing for the kind of fastener groups that would apply to spliced studs, only that I'd be happy to let such testing inform my work if it existed. I've seen stuff for fancier wood moment frames but have no apetite for tracking it down.

What I don't like is the eccentric load induced from the trusses overtop the wall (probably eliminated if we have 4 top plates)

I don't feel that the four top plates would help with that at all. What would help, in my opinion, is blocking at the top and bottom of the splice. I think that's why you saw several of us mention that.

Wood trusses are a different beast. A nail plated connection is very stiff, allowing adequate load transfer. That differs considerably from dowel type fasteners yielding in shear or local crushing.

A nail plated connection is a dowel type fastener. So is a toothed plate in many respects. I actually got my start as a designer of metal plate connected wood trusses.

In my mind, a truss and a spaced out stud splice have the following in common:

1) Only axial load and shear load on the fastener groups;

2) A meaningful degree of fastener slip which is typically ignored in routine design.

3) No individual fastener groups required to resist moment which is where, in my opinion, the fastener slip really starts to become a problem. Fastener slip in axial/shear connections tends not to amplify displacements quite the way that it does in localized, dowel fastener moment connections.