Maximum Length of wood shear on Overturning forces calculations 1

[RDMESH]

Hey all,

Is there any limitation on the length of wall that could be utilized for overturning/holddown capacities calculation on wood shear walls? For example, if the shear wall is 50' long , would it be effective to take the full length of shear wall to calculate tension or compression forces to determine hold down requirement. I am not aware if there is any limitation for the length of shear wall to calculate chord forces at end per NDS? Personally, i think the use of 50' length for overturning calcs will be ineffective on wood shear walls. I will appreciate any suggestion.

 

[KootK]

I don't have a definitive answer for you but I share the concern. I see this with unit demising walls a lot where they get quite long. I also wonder about unintended joints in shear walls. Often, when walls are prefabricated, I find that demising walls end up getting fabricated and shipped in as many as three or four pieces. You can stitch the segments together with fasteners easily enough but, at some point, I'd have to think that there would be performance penalties.

I find it a bit comforting to thing of wood shear walls not as giant rigid bodies but, rather, as rigid individual sheets of sheathing, each racking/rotating about it's own center of gravity. There is some validity to that model I believe and it gets me a bit closer to believing in long shear walls.

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.

 

[msquared48]

If you are concerned, then look to the code diaphragm limitations of 3.5 or 4 to 1. Provide additional hold downs at these locatons to break up the wall.

Mike McCann, PE, SE (WA)