King Stud nailing used to resist overturning?

[andr3w44]

Hello all,
I'm new to this forum so i hope this is the proper place for this question.
My question is when is it sufficient to use kingstud nailing to resist shearwall overturning without a hold down. I am looking over some calculations from an outside engineer(that has been slow to get back to me with answers) that my company has used on a recent residential project. In the link below I have attached a couple sheets of the calcs and highlighted where he uses KS nailing in some areas and hold downs in others with simular R_h values. Each highlighted wall is a shearwall with 6" oc edge nailing.Ive researched around and used NDS and Design of Wood Structures and im having no luck. Any guidance in the right direction is appreciated.
[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1503020226/tips/Mehan_Structural_Calcs_KS_overturning_iwgeu6.pdf[/url]

 

[JAE]

I'm not sure I understand the term "King Stud nailing". Is the king stud somehow fastened to the foundation?

Also - the calculations don't seem to meet the code combination of 0.6D +/- W. Instead it uses 1.0D +/- 1.0W.

Some may argue that the 0.6D + W combo is only for free standing overturning checks but the code doesn't really say that anywhere.



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[SwinnyGG]

The "King Stud" is just the first continuous stud between the top and bottom plates, either side of any opening with a header/trimmer/jack studs.

The only thing that comes to mind for the term 'king stud nailing' is the higher quantity of nails required to attach a trimmer or header to the king stud...

I don't see how this has any possible relation to overturning of shear walls.

 

[hokie66]

I think the engineer who came up with this description should define it, perhaps in a detail.

 

[JAE]

I don't see how this has any possible relation to overturning of shear walls.

I agree.

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[andr3w44]

I don't see how this has any possible relation to overturning of shear walls.

I agree.

this was my first thought as well.

I think the engineer who came up with this description should define it, perhaps in a detail.

ya it seems i may have to wait to hear back from him to see what he means here, I'll reply back to this tread once I do.

 

[Yt.]

The question is clear. The walls began to rotate as soon as the uplift force exceed gravity loads. Prior to that, the wall will be stiff as any other holded down wall. Also, maybe those holded down walls are sufficient to withstand wind or earthquake loads, the difficult part of these second view is to model the truth behaviour of the wall, with diferentes stiffness development through the horizontal forces, and there is insufficient documentation to learn quick about it, maybe that's why your engineer is taking more time than expected. On a third view, he might be distributing the stiffness to void rotations.

Personally, once I checked the lack of hold-downs in a residential project and a crazy contractor/labor man stopped to place the remainings ones as soon as I leave the place, noticed it on next visit. There are ways to install them if some are missing, but to me it was necessary to change somethings prior to complete the installation.

The nails increase sheathing lifespan, improve rigidity (better if anchored), and if balanced can control failure mode giving more ductility, but brittle failure if exceeded.

 

[msquared48]

I do not quite understand this either. If gravity loads are sufficient to resist overturning, no hold down is required, but the nailing to the shear wall end members (king studs et al) must still be developed.

I do not get the need for the king stud callout at all. To me, it's just confusing.

Mike McCann, PE, SE (WA)

 

[KootK]

We might be able to parse this out with a plan view of the referenced wall segments. Perhaps the king stud nailing connects the boundary studs to adjacent/perpendicular walls. In that case, the strategy would be appropriate whenever sufficient ballast could be engaged.

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.

 

[SwinnyGG]

Perhaps the king stud nailing connects the boundary studs to adjacent/perpendicular walls. In that case, the strategy would be appropriate whenever sufficient ballast could be engaged.

I thought of this initially, but why use the term 'king stud nailing' when corners between intersecting walls/segments have their own specific nailing standards?

A diagram would be indicative.

 

[FSS]

I can't get over the fact that the mysterious "king stud nailing" is on Sheet 34 of 37. That is a lot of hand calculation sheets for a residential project. Or any project for that matter.

 

[JoshPlumSE]

It's tough to tell from those calculations. Maybe the details would clear it up. My guess would be the following:

He's talking about FTAO (Force Transfer Around Openings) and he is either calculating the nailing required in the king stud to transfer the force around the opening, or he is talking about the strap forces perpendicular to the king studs that must be transferred around the opening.