Blocked vs unblocked shear walls

[Mountainrunner]

SDPWS shear wall values are for blocked shear walls...and to get shear values for unblocked shear a reduction factor applies...

Well...

Ho do you layout the playwood for a blocked / unblocked shear wall...

Per table 4.3A...you get 920/2 = 460 plf A.S.D capacity for a blocked shear wall with 15/32 plywood and 10d @4" o.c...

Well....

Would you be okay if contractor layout plywood per sketch #2 or should have he done it per sketch #1...


I know a blocked shear wall has its edges supported and nailed....but....sketch #1 seems to be more rigid than #2....

What is the plywood layout for a blocked / unblocked shearwall?

 

[skeletron]

It looks like the difference is plywood framed horizontally (#1) vs. plywood framed vertically (#2). And then #1 would have (hypothetically) more or better nailing than #2 because of the orientation of the edges.

 

[DaveAtkins]

My understanding is both of those options qualify as blocked shearwalls.

DaveAtkins

 

[TheDW]

They're both blocked, but check out note 2 below table 4.3A, when you're using 3/8" or 7/16" sheathing:

So they acknowledge that #1 is a bit more rigid. I'm not sure why they don't give us a factor to increase strength of 15/32" as well, but it is what it is

Edit: made pic a bit more readable

 

[dauwerda]

I would expect the contractor to layout per sketch #2 as it requires less material (no extra material for blocking). OSB is even available in 9' lengths to allow for this with 9' tall walls.

They're both blocked, but check out note 2 below table 4.3A, when you're using 3/8" or 7/16" sheathing:


So they acknowledge that #1 is a bit more rigid. I'm not sure why they don't give us a factor to increase strength of 15/32" as well, but it is what it is

I expect this has more to do with the buckling strength of the sheathing. 16" OC studs provide more out of plane bracing to the panel than 24" OC would. OR if placed with long dimension across studs you get a continuously supported panel (pin-spt-spt-spt-pin) as opposed to pin-spt-pin. Both of these options will increase the buckling strength of the panel therefore allowing the 15/32 inch values.