Ring Shank Nails

As I wrote about previously, the release of 2005 NDS Design Aid #4, "Post Frame Rink Shank Nails", allows designers to assign shear values for Ring Shank nails which have not been available since the 1997 NDS. Also referred to as Post and Framing Nails or Pole Barn nails, the shear values are currently a bit conservative, I believe, but current testing being sponsored by the NFBA will provide the technical basis for higher (more accurate) design values for shear AND withdrawal in future editions of the NDS.

One difficulty in discussing nails in general and Ring Shank nails in particular is relating the penny designations common in the construction and building fields to the design standards such as the NDS. My good friend and fellow NFBA T&R Committee Member at Maze nails, Tom Koch, was gracious enough to help me close the loop on this little issue by pointing out to me how the penny designation relates to a specific length in inches and also how the gauge number relates to a decimal inch diameter.

I used his information and Maze's catalog to relate to the NDS for a common side member thickness (1.5") for two common materials used in my projects: Southern Pine (G=0.55) and Spruce Pine Fir (G=0.42). This is the table I generated to show the allowable "unadjusted" shear for these single shear (two-member) connections:


Keep in mind that, for a given diameter, as long as the length of actual penetration, "p", into the main member is at least 10 times the nominal diameter, the shear capacity of the connection does not increase with increased length. The penetration must always be at least 6D and can be adjusted for penetrations between 6D and 10D by taking the design value from the table and multiplying it by the actual penetration p/10D.

For species of woods other than Southern Pine and SPF, different shear values are assigned. The shear values can be adjusted for other considerations in the NDS, such as Duration of load which allows a 15% increase adjustment when the shortest duration of load applied is snow, and a 60% increase adjustment when wind is included in the design requirements.

The best recommendation I have for specifying nails is to use what I call the inch by inch approach: specify the length in inches and the diameter in inches, and then the type of nail (Common, Box, Ring Shank, etc.). For example, 4"x0.177"Ø R.S. Nail is a better description than a 20d R.S. Nail, but both "might" be used refer to the same nail. If penny designation is desired because of common relation in the field, I would suggest using that in addition to (and not instead of) the length and diameter in inch by inch format, such as: 20d 4" x 0.177"Ø R.S. Nail.

I hope this discussion helps you with Nail specifications and reduces errors in the selection and specification of the proper nails for your jobs!

Aaron Halberg, P.E.