Wood Diaphragm Nail Slip Maximum Load
Wood Diaphragm Nail Slip Maximum Load
(OP)
If you look at table C4.2.2D in ANSI/AF&PA SDPWS-2008 (http://www.awc.org/pdf/2008WindSeismic.pdf), for 10d common nails the maximum fastener load for calculating nail slip is 260lb (this is for deflection, so ASD loads).
If you calculate the fastener strength for a 10d nail connecting plywood into framing (assuming the plywood's specific gravity is 0.5 and framing also), you get the following load from Table 11Q in NDS 2005 multiplied by 1.6 wind factor and 1.1 diaphragm factor:
15/32" plywood : 88*1.6*1.1 = 155#
1" plywood : 118*1.6*1.1 = 208#
1-1/4" plywood : 118*1.6*1.1 = 208#
What am I missing? Why would they allow for a 260# maximum fastener load when in no situations is that plausible? I must be missing something.
Thanks.
If you calculate the fastener strength for a 10d nail connecting plywood into framing (assuming the plywood's specific gravity is 0.5 and framing also), you get the following load from Table 11Q in NDS 2005 multiplied by 1.6 wind factor and 1.1 diaphragm factor:
15/32" plywood : 88*1.6*1.1 = 155#
1" plywood : 118*1.6*1.1 = 208#
1-1/4" plywood : 118*1.6*1.1 = 208#
What am I missing? Why would they allow for a 260# maximum fastener load when in no situations is that plausible? I must be missing something.
Thanks.






RE: Wood Diaphragm Nail Slip Maximum Load
RE: Wood Diaphragm Nail Slip Maximum Load
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.
RE: Wood Diaphragm Nail Slip Maximum Load
ASD load for this is 2435plf/2 = 1217.5 plf
The edge of the diaphragm has fasteners every 2in. So the load per fastener is 203# and the allowable load is 155#.
So why would they design a diaphragm that has 203# per fastener when the allowable for the conditions listed is 155#. I find nothing about this in the commentary or any diaphragm design guides. I've designed diaphragms using this before I just never noticed this before. What am I missing.
RE: Wood Diaphragm Nail Slip Maximum Load
RE: Wood Diaphragm Nail Slip Maximum Load
We're going to connect to the existing floor diaphragm of building B to the wall but how dependable the existing diaphragm is a judgement call (its 58.5ft x 58.5ft building so even if the diaphragm has barely any capacity, the wind load is only 142plf at the roof it should be ok).
So just to give us some piece of mind we're going to heavily reinforce the diaphragm where we connect to the wall to make a "mini" diaphragm capable of resisting all the wind load.
RE: Wood Diaphragm Nail Slip Maximum Load
Second, why are you going to the commentary?
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.
RE: Wood Diaphragm Nail Slip Maximum Load
I use equation C4.2.2-1 on page 54 which has nail slip as a separate calculation, 0.188Len which is also the same as the IBC equation.
en = (Vn/769)^3.276 Where Vn is fastener load (Table C4.2.2D on npage 57).
If I'm calculating wind deflection why would I use seismic loads. Also, if you look at design guides (ex: http://www.ce.udel.edu/courses/CIEG407/APA%20Diaph...) they use the wind load for Vn when calculating deflection.
RE: Wood Diaphragm Nail Slip Maximum Load
This may be the reason for the 260 lb/nail requirement.
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.
RE: Wood Diaphragm Nail Slip Maximum Load
RE: Wood Diaphragm Nail Slip Maximum Load
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.