Shear Wall

[BSVBD]

The East Elevation has canine kennel windows. The space between the windows does not satisfy the Shear Wall Aspect Ratio requirements.

If i provide a "Shear Strut" header above those windows, can i use the area above the windows as a portion of my shear wall between wood columns 1 & 4?

Assuming there is a way to accomplish this:

Do i need to to provide holdown anchors at the base of wood columns 2 & 3 in addition to holdown anchors at the base of wood columns 1 & 4?

Do i need to apply any portion of the total shear wall reaction at that strut / header vertical elevation, parallel to the X-X, to those wood columns 2 & 3?

What else do i need to know?

Thank you!

 

[KootK]

Firstly, if at all possible, I'd try to get the job done with just the shear wall segments between #1 and #2 (Maybe even just left of the door). Based on what I'm seeing, that looks workable and would probably be a lot simpler to deal with.

Secondly, as an out there kind of idea, you could combine your scheme with little vertical trusses that extend from your shear strut down to the foundation. This would circumvent the aspect ratio business. How you would reconcile this approach with code provisions is the part that I would struggle with. I've seen trussed shear walls in California though so it's clearly possible.

On to your actual questions:

If i provide a "Shear Strut" header above those windows, can i use the area above the windows as a portion of my shear wall between wood columns 1 & 4?

I think so. I question the effectiveness of the approach however. You'd still have to deal with 100% of your shear in the wall segments either side of the kennel windows. Additionally, what you'd be doing here is essentially creating a moment frame system with a rather long beam. As with ordinary moment frames, effectiveness drops off pretty quickly when the beams start to get long.

Do i need to to provide holdown anchors at the base of wood columns 2 & 3 in addition to holdown anchors at the base of wood columns 1 & 4?

Quite possibly. #2 and #3 will be involved in resisting some of your overturning (like a coupled concrete shear wall). If overturning results in tension, you'll need the hold downs.

Do i need to apply any portion of the total shear wall reaction at that strut / header vertical elevation, parallel to the X-X, to those wood columns 2 & 3?

The usual way to do this is to run your shear strut past the opening at #2 and #3 to develop as collectors into the wall sheathing on either side. Obviously, you've got limited space for that. I suppose that you could deal with the forces as weak axis bending in the columns at #2 and #3 but that would tax the columns pretty severely.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[DaveAtkins]

Would the perforated shear wall method work in this case?

DaveAtkins

 

[manstrom]

Use a perforated analysis and save the headache.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[sponton]

If they use a perforated analysis, those little sections between the windows do not help since they probably surpass the aspect ratio. The best way is to use just sections of the wall and treat the portions of the wall that do not fulfill the aspect ratio req't as struts/collectors, [just guarantee that they're properly nailed to transmit stresses via the top Pl's, and the nailing is properly specified.

I agree with KootK, it seems that it is a relatively long wall, so I'd use only sections 1-2 and perhaps 3-4, only question would be properly nailing everything and the collector/strut.

Even when we design perforated walls we specify hold downs in every opening, depending on how they are to be sheathed, we also include the shear wall nailin schematic, I've seen some horrible nailing in the field, so it's better to be safe than annoyed later.