Lateral wind loads - internal masonry walls 1

[LR11]

I'm looking at a dwelling with reverse brick veneer construction with a light sheet truss roof. Single storey.
The external leaf/wythe is timber and the internal leaf/wythe is brick. The internal walls are brick.

With respect to the capacity of the internal walls to transmit shear loads:
(1) Is it unreasonable that the internal walls need to be anchored for uplift. The first attached image seems to show a steel rod, presumably for this.

(2) Another question that I have is with respect to the transfer of wind loads between the external wall and the internal perpendicular walls.
Do you ever see many ties as shown in the second image ... or do you assume that typical ties (spaced at 600mm or 300mm near opening and edges), transfer this load to the internal wall?
Issue with internal pressures as well? Or do you rely on shear capacity of mortar?

 

[JLNJ]

I would expect the external walls to transfer the load to the diaphragm and the diaphragm would transmit the shear loads directly to the interior shear wall.

 

[LR11]

Thanks for the comment JLNJ. I'm inferring that you would not have the ties in the vertical strip

 

[JLNJ]

If you want to make your exterior walls act as “flanges” which act compositely with the shear walls (to stiffen up your structure), then these ties would play a serious role and things get a bit more complicated.

If you are in a high seismic area, there also may be additional prescriptive code requirements for tieing walls together.

Determine the load path and design the pieces along the path.

 

[LR11]

OK thank you.
The reason I brought it up is because the internal wall will not have lateral support at the top. The builder will install the outer timber wall leaf/wythe first, followed by the truss and the internal brick is installed as a veneer.

Did you have any experience with query (1)?

 

[JLNJ]

If the shear is big enough, yes the shear walls can overturn and need to be anchored.

The real question is how does your shear load get into the internal wall? A shear wall with no lateral restraint at the top? Seems rather unconventional. I would need a better diagram of your structure to comment on whether or not you have a viable load path.

 

[LR11]

JLNJ, thanks for responding. Firstly to clarify, the term "internal wall" that I used in my last post, means the internal leaf/wythe.

With respect to how the shear load gets to the shear wall, that's one of the question in the thread.
So for the internal leaf/wythe, the base is anchored to the slab, and the sides are attached to the perpendicular shear wall, 3 of 4 sides are restrained. The top probably won't be anchored to the truss.

So I'm inferring that the forest of ties cause the internal leaf/wythe to go into flexure, restrained at the bottom and sides.

When you use the term "A shear wall with no lateral restraint at the top? Seems rather unconventional." ... is this not the case with non-load-bearing walls? I have always thought that the term load-bearing, was for vertical load only. You've got me thinking on this. Is it required for lateral bending effects? Could you please clarify as it's important.

The sketch below shows the situation. See the gap between the internal wythe and the external.

EDIT: Also, do you normally allow for the mortar to have a tensile capacity, a number of 0.2MPa I've seen mentioned.