Originally Posted By: mcyr
This post was automatically imported from our archived forum.
This might answer the question.
Hopefully it was written up properly and not have to be so technically correct.
On occasion installers will use whatever nail they have in their nail pouch to fasten the connector. Or, if they look at the specifications and see ?common? nail might assume that a 16d sinker or gun nail with a similar size designation is equal to a 16d common nail.
Catalogs from the major connector suppliers include instructions to the installers cautioning them about making fastener substitutions. Since the default specification is for common nails and common nails are seldom ?commonly? available, one cannot assume that the installer will even have the correct fastener on the job site, let alone be certain to use it. The catalogs include information on how to adjust for fastener substitutions, but these charts may not be available at the time the connectors are installed.
It is critical that the installer understands that all the specified fasteners may be required to achieve the design capacity. The load capacity for each 16d common nail in DF/L is 134 lbs. A total of 20-16d common nails are specified (20 x134 = 2680 lbs). If more than one nail is omitted, the connector will be overstressed because too few fasteners were used.
If 16d sinkers are substituted for 16d commons, the carrying capacity is only 112 lbs per fastener (20 x3 112 = 2240 lbs). One can also use the reduction factor of 0.84 from a supplied table (2680 x3 0.84 = 2251 lbs). In either case, the connector will be overstressed because the wrong diameter fastener was used.
If the specified common nail is being driven into SPF instead of DF/L, an adjustment of 0.86 will have to be applied to the load (2680 lbs x 0.86 = 2305 lbs) because fasteners do not have the same capacity in every species of lumber. The connector might be overstressed and fail because it's being nailed into a different material than originally assumed.
If the member that the fastener is being driven into is thinner than 12 times the diameter of the fastener, an additional reduction needs to be taken into account using the following equation:
The minimum penetration of a 16d common nail is 12 x 0.162 = 1.94". If the member is a single 2x, the edge dimension is only 1.5". Thus, the reduction equation must be applied.
The load carrying value of each of the 16d common nails nailed into the single 2x is reduced from 134 to 103.6 lbs (20 x 103.6 = 2072 lbs). This situation might also be the cause of a connection overstress.