Multi story wood structure stud wall plates

[ars001]

I think I go around and around with this situation everytime I look at my detail. I have a 4 story wood structure (hotel) that is framed with 2x6 stud walls and 24" deep pre-engineered roof trusses. My questions lies at each level where the stud wall sits on my trusses. I usually provide a 2x6 sill plate that sits on my floor sheathing that sits on a continuous 1 1/2" rim board. The trusses butt into the rim board and sit on a double top plate of my stud wall. How do I analyze this system when transfering my vertical stud loads from above? Is it just and accepted practice just to stick with a single sill plate and a double top plate? I usually don't worry about this but with this being 4 stories and all I probably won't sleep so well.

 

[msquared48]

If these bearing walls are also shear walls, depending on the load to the wall, the perimeter members, to include the bottom plate, will have to increase in size with increased nail9ing. Plus you have the deep beam spanning effect of any plywood on the walls. Gyp is questionable for the sameeffect, but id realistically add to the beaming effect of a wall, although it is questionable to consider this as such by code. Additionally, as you progress down to lower floors, the studs increase in size and spacing.

I would be primarily concerned with the shrinkage issues, and the isolated column pressures though before I would be concerned with the bearing walls. I have seen 95% of the post-construction structural problems in those two areas.

Mike McCann
MMC Engineering

 

[DaveAtkins]

If you are concerned with gravity loads, here is how I look at it: the rim board will transfer the stud loads from above into the studs below without bending the double top plate below. The double top plate should be checked for bending if the floor trusses at the floor in question land between the wall studs below.

DaveAtkins