Perforated Shear Wall

[kcjenkins]

In the IBC do the aspect ratio requirements for wood shear walls apply to perforated shear wall (fully sheathed) "segments" or is that just for normal wood shear walls and segmented wood shear walls? The code does not explicitly state that the aspect ratios are a requirement for perforated shear walls.

 

[dougantholz]

Aspect ratios are for both the wall as a whole and the pier. The benifit is for piers you only have to count the height of the opening for the height of the pier.

 

[AggieYank]

IBC 2305.3.3 "Size and shape of shear walls and shear wall segments within shear walls containing openings shall be limited as set forth...."

IBC 2305.3.7.1 Force Transfer around openings. "...The height of a wall pier shall be defined as the clear height of the pier at the side of an opening...."

From the diagram in figure 2305.3.4(b), the top diagram shows the "clear height" as bottom plate to top plate. Now, it's a bit confusing because the middle diagram shows the "wall pier height" as the height of the door/window, and you're supposed to use the "clear height of the pier." However, my take is that the aspect ratios should use the "wall pier height". It'd be easier if the code writers had used "wall pier clear height" for the label of the middle diagram, so that it matched the written part.

So in summary, I'd use the wall pier height for the aspect ratio. However, I always make sure I'm using a minimum of 2'-3', even if by code I can make the numbers work with a 1.25' wide shear wall, or something that seems tiny.

 

[kcjenkins]

Thanks for pointing out the wall pier height at openings, I am able to get my perforated shear walls to work with this limitation.

 

[kcjenkins]

I am still unsure if an aspect ratio applies to perforated shear wall segments.

Figure 1205.3.4 only mentions segmented shear walls and shear walls with force transfer around openings. Also 2305.3.7.1 mentions figure 2305.3.4, while 2305.3.7.2 Perforated shear walls: does not say anything about a limiting height-to-width ratio for perforated shear wall segments

I wish the code would make this more clear. I do not know if you can eliminate this limitation for perforated shear wall segments, but there is nothing that says there is a limiting aspect ratio for perforated shear wall segments.