horizontally discontinuous studded wood frame walls.

[Materofact]

i’m trying to explain to junior engineers why you can’t have a tall interior stud wall (like 24’) with the stud walls broken with a horizontal member midway i tell them that it’s a joint and out of plane loads (earthquake) loads will blow it out and it not proper construction to be done. but i’ve never really taken it past the idea. but what is the mechanism and calcs to prove it? then they ask what if you span plywood on the wall centered over the “joint”. or what if you use screws instead of nails to avoid withdrawal as it moves out of plane ? tell them no matter what it’s perpendicular to grain loading and to shat up?

 

[jayrod12]

There's a bit of nail/screw slip that really causes any sort of constructed joint like that to be flexible. No matter the number of fasteners.

And what about the future when someone renovates the inside or outside and doesn't recreate that continuity detailing. Then you've got a knuckle that will visibly move.

 

[Mike Mike]

yes I usually shat up, I know I know, shatting down has the proven track record, but I don't give a shat what they say, I like to reverse gravity in my restroom

I agree 100% jayrod, wood moment connection deflections are hard to quantify. Side-track warning: I'm reminded of a long-standing debate in our office. some engineers say the unbraced length of a wood stud wall resisting out of plane wind load should be the length of the stud itself. I say you should include another 4.5" for the double top plate and bottom plate. If you discover one of your headers in the field doesn't quite work, you don't tell the GC to lop 3" off the header next to the jambs and nail a few plates onto the end of the header.

 

[molibden]

What if such a wall has two perpendicular walls? If you connect horizontal plates to perp. walls, studs are basically prevented from buckling out of plane. I don't like it but in some cases I allow contractors to build walls on top of walls. If walls are braced at reasonable spacing.

 

[phamENG]

The only way this works is if you have a member running between them that is capable of spanning horizontally (a wind girt). You have to be careful with deflections, though, since the combined deflection of your wind girt and studs can get pretty extreme.