Wood Shear Wall Distribution

[NLOKyle]

I'm having trouble determining the best way to distribute shear throughout the walls on this floor plan. If anyone has any suggestions or has designed a plan with mostly angled walls I would love to see an example. The diaphragm design force at the roof level is 30k seismic.

 

[EngDM]

Would something like this work? Not sure if the horizontal one is even needed, but it would certainly add stability.

Depending on scale you'd want to make sure your diaphragm is rigid, or account for it not to be. There are some accidental torque loads to take into consideration as well, so that's why I've chose the walls further out.

 

[driftLimiter]

I'd say it will mostly depend on the diaphragm type.

If its flexible I'd try to get shear on each of the (3) sides of each protrusion. Then try to get an approximately rectangular region in the middle.

If its rigid you may be able to push it more like what EngDM sketched.

There is much to consider that you haven't included in your post.

 

[NLOKyle]

I was looking for suggestions on the best way to design it. Theres a reason I didn't include those details.

 

[EngDM]

I was looking for suggestions on the best way to design it. Theres a reason I didn't include those details.

If its flexible I'd try to get shear on each of the (3) sides of each protrusion. Then try to get an approximately rectangular region in the middle.

 

[driftLimiter]

If you want better suggestions you need to at least provide some more info.

How many floors, What is the construction type. What lateral system. Seismic?

purely from a lateral force horizontal distribution point of view i would say you want to have a rigid diaphragm. Its far more capable of getting the load to isolated locations on this floor plan.

But thats never really the deciding factor on these things.

 

[Flotsam7018]

I think your best bet for a layout like this will be modelling the diaphragm and shear walls elements for a semi-rigid analysis. From there I think the tricky part would be detailing the chords, collectors, transfer diaphragms to some justifiable means.

 

[milkshakelake]

A safe way to do it without involving more details is to make the entire perimeter (except the massive openings near the top) into shear walls. Use Force Transfer Around Openings (FTAO) detailing or perforated/segmented shear walls where you have openings. And also add some shear walls around the core. This will cover the flexible diaphragm case except at the top. For wood buildings, the exteriors tend to be sheathed with plywood anyway, so it's just a matter of adding hold-downs and calculating the nailing pattern.

Where the diagonal shear walls intersect with the rest of the building, you'll need diagonal collectors. Or not; I haven't really heard of a diaphragm tear in my life. But engineering principles says you should add them.

 

[EngDM]

Use Force Transfer Around Openings (FTAO) detailing or perforated/segmented shear walls where you have openings.

Some places don't allow FTAO, just thought I'd throw that out there.

 

[phamENG]

Some places don't allow FTAO, just thought I'd throw that out there.

And where would these terrible and unspeakable places be?

 

[atrizzy]

pham, my copy of the 2014 CSA O86 reads, 11.3.3.3 - "shearwalls with openings shall be analyzed as the sum of the separate shearwall segments. The contribution of sheathing above and below openings shall not be included in the calculation of shearwall resistance."

It also limits the aspect ratio of wood shearwalls to 3.5:1

 

[phamENG]

Ah...Canadian code. That's a bit of a bummer for you guys. FTAO has been a lifesaver for me on a few projects. We have the same aspect ratio limits, but when using the FTAO methodology you apply that to the wall segment where b = width between openings/width from edge of opening to end of wall and h = height of the opening.

 

[atrizzy]

Yes, I've used that for US projects ages ago. Definitely a life saver and I wonder why they're reluctant to allow it here.
I mentioned my copy is the 2014 version because they may well have since changed it in 2019.

 

[EngDM]

I mentioned my copy is the 2014 version because they may well have since changed it in 2019.

99% certain it's the same in 2019 version, since I'm not sure where else I would have read it otherwise.

They are limited to 3.5:1 for b:h or h:b?

 

[atrizzy]

H:B
They're not THAT strict...

 

[NLOKyle]

driftLimiter, literally every question you asked is given already. The original post said its seismic. I showed both floor layouts labeled main floor and upper floor (2-story). The title of the post is wood shear wall distribution, meaning the construction type is wood. Amyways, I appreciate your input!

 

[EngDM]

driftLimiter, literally every question you asked is given already. The original post said its seismic. I showed both floor layouts labeled main floor and upper floor (2-story). The title of the post is wood shear wall distribution, meaning the construction type is wood. Amyways, I appreciate your input!

You uploaded a file, and I posted a screenshot of it without the drawing titles. It's entirely likely that driftLimiter looked at my screenshot instead of downloading your file. Regardless, input was given around how people would go about it, and it came off as though you wanted it done for you? I'm not sure if that was your intent but that is how it reads.

 

[milkshakelake]

OP doesn't acknowledge advice given, attacks others...yeah, I'm moving on.

 

[jerseyshore]

Guys I have a few jobs I need you to get done for me this weekend. Don't ask for any details, those aren't important, just design it and get it out the door. Have to watch redzone tomorrow. DL this is all your fault.

 

[lexpatrie]

This doesn't look very viable. In addition to a lack of knowledge of how to do it, there doesn't look like there's enough shear walls anyway, and the diaphragm spans, based on the scale of the drawing and door openings looks pretty large as well, let alone (if it's rigid), the torsional component. Generally these are all open sided diaphragms and not even that, they are single sided because there's no shear wall on the other three sides, the whole approach looks unworkable. I think you need to ask someone in person, i.e. a senior engineer in your company.