osb in lieu of tie downs?? 1

[AlpineEngineer]

Hey guys,
I'm wondering if you guys have seen the APA publication for "using wood structural panels for combined uplift and shear resistance". Basically they are using properly placed and nailed OSB in lieu of shear wall holddowns. It seems logical, I'm sure its been tested, but still I hesitate. At 1500plf of uplift resistance for 7/16" sheathing its a pretty healthy credit. I am assuming if there were any joints in the OSB they would need to be blocked since the applied load is at the top?
Any thoughts are appreciated.
Thanks a ton guys!!

 

[UcfSE]

Threaded rod systems likely rely on this concept a lot. I don't think it's intended for shear wall hold-downs, but rather the truss uplift combined with shear in a shear wall.

I haven't used this myself, but I don't do much wood either. I don't see why you shouldn't if everything, including deformation compatibility, is examined. One thing I would worry about is relying on something very different from the norm. You're hoping they'll actually read the plans and the inspectors won't give you a hassle because you have no straps.

 

[msquared48]

I have not taken a look at the publication, but find it REAL REAL hard to accept any notion of using the nailing of OSB to sill plates as a substitution for a holddown.

Regardless of what the publication says, my enginering requirements will not change in this scenario.

Mike McCann
MMC Engineering

 

[boo1]

Agree with Mike about nailing. In the real world the nailing would be very very hard to follow.

 

[RARWOOD]

The 1500 plf number you refer to, is a maximum uplift load allowed in the panel before the calculation of combined tension and shear is required.

The tenisle capacity of the wall studs and the panel will generally exceed this number. So the controlling factor will ussually be the strength of the fasteners.

The APA Technical Note is for the transfer of uplift forces between floors on exterior walls. The attachment of the sheathing to the sill plates is a seperate problem.

To utilize the sheathing the nailing and sheathing placement has to be properly detailed. The APA Tech. Note provideds several typical details. Like all shear design problems a load path must be maintained.

 

[UcfSE]

See also an article in STRUCTURE magazine from March 2006 if you have access.