Wood Framed Inside Corner w/ Chord/Strut Forces in Each Direction -- Detail Ideas

[zrck99]

Anyone out there have a slick detail that they've used for an inside corner where you have chord/strut forces in each direction? I feel like this is a common enough scenario that there is probably a common way of dealing with each force but I haven't found a great option in the connector catalogs I have. I plan on connecting the girder truss to the left-right double top plate with a Simpson DSCR/L-SDS3 drag strut connector but after installing that, it seems like I've blocked off my options for connecting the vertical truss to the perpendicular double top plate. I can slide the girder and regular truss in either direction a bit in order to get things to fit but am not sure what would be typical -- I'd prefer not to send a crazy hand made detail out if people know of a good way to do this with standard manufactured wood connectors. Thoughts?

Thanks,
ZRC

 

[ARKeng]

You slide your girder truss a bit south and connect it with the Simpson DSC (remember you'll want this common truss to be the same length as the ones to the left). You connect the common truss with just a strap on the bottom of the truss using either a cut coil strap like a CS16 or a pre-cut strap like the LST/MST series. (Sorry don't have my Simpson book in front of me at the moment).

 

[zrck99]

If the typical truss is in compression, how do you handle that force? I agree for the tension case that you would be good with a strap but when the load reverses you still need something else.

 

[KootK]

For the compression case, I suppose that you could install snug blocking between the adjacent bump out trusses that move the load down into the top plate.

Usually this situation is obviated by stabilizing the bump out more or less independently with its own shear walls. Not possible here? Big openings in the bump out walls at the re-entrant corner?

 

[zrck99]

KootK,

I've attached my rough framing plan that I'm marking up with a handful of notes.

Blue highlighter and blue pen relate to windload from top of page to bottom, purple highlighter are marks for wind load right to left.

I've noted (3) 3'-0" wide shearwalls and (1) 15'-9" wide shearwall that I have available in orange. Because I need to use the 15'-9" wide shearwall, I'm not sure how to get around the purple 900lb chord force.

For the case with wind load from top of the page to bottom, I have designed as one big diaphragm. This is causing my 2500lb chord force shown in blue pen. When I use a transfer diaphragm to dump the 2500lb load into the diaphragm, I end up with a 400lb vertical chord force in that corner. If I were two break it into two separate diaphragms and utilize the wall just below the inside corner, I would still collect enough force in that corner that I would have to have some sort of compression connection in that corner.

Any thoughts?

Thanks,
ZRC

 

[KootK]

I get why you're trying to do what you're trying to do now. Thanks for the sketch. See some additional ideas below.

 

[zrck99]

KootK,

I think I may be a little confused. The way that I'm thinking about it, for the purple wind load from right to left, I have to have a truss go full width across the building to act as my diaphragm chord. So that 900lb force has to be shared between the double top plate and truss through that corner in order to get my load out to the 15'-9" wide shearwall. Does that make sense or am I missing something?

Thanks

 

[KootK]

I don't think that you're confused at all. Just, perhaps, not seeing the full range of possibilities available to you. You need something to deal with the 960 lb chord demand that you've identified. That, to resolve torsion on the bump out diaphragm that has arisen because you've shifted some of your shear laterally over to the 15.75' wall. That "something" could be either one of these things:

1) Load delivery into the full width truss per your original proposal OR;

2) Load delivery into the bump out shear wall per my previous proposal.

It doesn't much matter where you dump that 960 lb load so long as you take care of it somewhere, in a way consistent with equilibrium. Option #2 might just make for simpler detailing, that's all. It might also make for a more natural load path given that the bump out diaphragm really cannot rotate without imposing some drift on that short bump out shear wall anyhow.

 

[zrck99]

I’m not at work anymore do I just drew up a quick sketch with a made up 10 lb/ft load and easy dimensions to work with. Is this what you are suggesting? Where the chord breaks at the corner the bump out will behave like a 3sided box?

 

[KootK]

Is this what you are suggesting? Where the chord breaks at the corner the bump out will behave like a 3sided box?

Yup, that's pretty much exactly the sketch that I would have sent you if I weren't Eng-Tipping from my recliner like a boss while I watch football. The only difference would have been that, based on your floor plan, it doesn't appear to me that you've got a viable wall on the right side of the three sided box.

 

[zrck99]

Yeah, I don’t have a good walk on that side but the loads over there are at least smaller which is a plus.