Shear Panel Nail Spacing < 2"

[PMIDesignGroup]

So the framer must love his power nailer because for a 10d 2" o.c. CDX plywood shear wall, he did 1.5"-2" o.c., two rows staggered on the double 2x4 chords and perimeter. The result is for many nails (in adjacent 2x4's) to be approx. 1/2"-1" apart, measured diagonally. The building department is asking for clarification if this tighter-than-specified spacing is an acceptable condition. Are there any resources out there that recommend how to apply a strength reduction factor for TOO MANY nails in a shear panel? The Doug Fir #2 studs and plywood do not show any signs of splitting, just a ton of nails.

 

[efsinc]

NDS provides formula to determine reduced value of nails with spacing closer than a minimum spacing for full value.
Now from memory (Better double check this in NDS!), I think minimum full value spacing is same as minimum full value penetration. And reduction is linear, and drops off cliff to zero at spacing equals half minimum spacing for full value. But for some reason I think reduction is linear from 100% at minimum full value spacing to 0% at 0" spacing, but is truncated at 50% spacing, such that 49% spacing is 0. I need a beer.

 

[PMIDesignGroup]

Thanks a lot efsinc! The approach resulted in a reasonable analysis. I'll buy you that beer if you find yourself in the Silicon Valley area!

 

[TDIengineer]

Like his post, sir! that's not quite a beer, but is better than a pat on the back..

 

[JoshPlumSE]

If anyone knows the actual NDS reference for this, I'd love to hear it. I was interested and took a quick look through my "SDPWS" (special design provisions for wind and seismic), but didn't find anything.

 

[msquared48]

I am not sure that the NDS addresses that, but the APA might as it does get into plywood diaphragm nailing quite heavily. Might check there.

Mike McCann
MMC Engineering

 

[msquared48]

Interesting to note the 2008 NDS Wind and Seismic SDP with Commentary, section 4.3.7.4(a) where a nail spacing less than two inches is implied, but no values noted any any if the tables I can find. Might check the 2012 commentary.

Mike McCann
MMC Engineering

 

[woodman88]

The spacing requirements in the NDS do not apply to dowel-type fasteners with a D less than 1/4". See 2001 NDS (also I think the 2005 NDS) section 11.5.1.1.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.