Correct axial load when stud and joist/truss spacing do not align?

[MJC6125]

I wanted to get some opinions on this subject. If you have a wood stud wall with studs spaced at 16" oc supporting trusses spaced at 24" oc, what is the proper axial load to design those wood studs for? Would you design them for a 16" tributary load or would you design them for a 24" tributary load assuming if a truss lands directly on a stud all of its load will go to that stud and not distribute out to the adjacent studs at all?

If you are designing for the stud spacing tributary, what exactly is the mechanism that transfers the load into those adjacent studs? Though the sheathing kind of like a load corbelling in a masonry or concrete wall?

I searched through past threads on this topic, but most of the ones I found were more focused on whether the dbl top plate can span between studs if the truss lands at midspan of the top plate. Obviously that would also be a case that needs to be checked.

 

[KootK]

In the scenario that you've described, I feel that each stud should be designed for the full reaction of the truss that may wind sitting right on top of it. A double top plate isn't going to do much to distribute load in that situation. I will say, however, that I have seen plenty of engineers do other things, including aggressive live load reduction, in such situations. That's at least somewhat more defensible when there's a deep rim member in play and loads are delivered through that rim member in a multi-story structure.

 

[dik]

The sheathing may help to distribute the load a bit... never been overly concerned except for tall walls and long span trusses...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JoshPlumSE]

To some extent, this is splitting hairs.

Personally, I would think it would be better to to design the studs for the worst case condition where one stud perfectly aligns with the one roof truss.

Then again, I'm not going to criticize an engineer for designing for a distributed load that is equal to Truss Reaction / 2 ft which means an average stud load of 16/24 * truss reaction. I may not want to put my stamp on that type of project. But, if it's detailed out well and the load path makes sense, that's a lot more important (to me) than a 30% overstress of any single stud or joist.