Fastener Head Pull-Through in Wood

[Deadblow]

I am designing the anchorage of a double 2x8 wood plate to concrete using a post-installed screw anchor. The applicable code is the 2018 IBC and the 2018 AWC NDS. I have the anchor design and the lateral load on the wood complete and there are no problems there. How do I calculate the fastener head pull-through value? The fastener head diameter is 1.125" and the side member thickness is 3". Section 12.2.5 of the 2018 NDS limits the range of fastener head diameters to 0.50" and the side member thickness to 1.5". I have a tension load of 600 lbs at each anchor due to overturning. I'm not against using washers if I need to, but I'd like to prove whether or not they are actually needed and how big they need to be if indeed they are required. I have over 500 of these anchors to install, so it's worth the time to use the most economical assembly.

Thanks!

EIT

 

[Eng16080]

I would use Equations (12.2-6a/b) although I think, per my interpretation of Section 12.2.5 that you might not need to check head pull-through considering that you're not "within the range of fastener head diameters, DH, and net side member thicknesses, tns, given in Table 12.2F." Still you might as well check it to see where it comes out. Likely it will not control for the values that you have. Another check which you might also do, but is probably not necessary, is to check bearing perpendicular to grain for the area of the head in contact with the wood.

 

[Deadblow]

Eng16080,

Thank you for your response. As you suggested, I did use Eqs. (12.2-6a/b), but I don't think they are applicable due to being outside of the range of head diameters and side member thicknesses. Good call on checking the bearing perpendicular to grain. That check proved that I need washers! I wasn't even thinking about the bearing perpendicular to grain.

I would still welcome suggestions on fastener head pull-through calculations when the dimensions fall outside of the range of values given in Table 12.2F of NDS 2018.

EIT