Timber Frame Tension Joinery - Timber Frame Engineering Council

For softwood members the NDS requires that a distance of 7D be provided from
the center of the bolt to the end of the tension member (l v ) and that a distance of 4D be
provided from the edge of the mortise to the center of the bolt (l e ) (where D is the diameter
of the steel bolt).
Since these requirements are based on connections tests with steel bolts, a wood peg
used in the same application would have a much larger diameter than a steel bolt. It does
not seem reasonable to assume that for a given load, a much larger end distance is required
for a wood peg than a steel bolt, just because the diameter needs to be greater. Therefore,
relationships must be drawn between the required wood peg diameter and an equivalent steel
bolt diameter. End distances and perhaps edge distances would then be determined by using
the equivalent steel bolt diameter.
To determine the size of a wood peg or pegs needed in a connection, one would
Figure 3-11 Standard Connection Geometry
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