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RE: Timber Truss Gusset Plate

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If all your lines of force go through a single point then there are no
twisting forces in the members outside of the joint, and it can be designed
as pinned.

However, this means that everything must line up through this point.  One
situation where this might not be the case is if the diagonal web member is
a very shallow or steep angle with an uneven end cut.  To make the gusset
plate smaller, you offset the bolts away from the centerline of the member.
Now, the line of force no longer runs through the common point and moment is
induced in both the connection and the diagonal member.

Back to your specific situation, I can think of one condition that would
cause force to be transferred through cross-grain bearing.  If the holes
don't line up exactly right during construction (say, the diagonal member is
slightly too long), the end of the diagonal member can be pressed hard
against the side of the vertical and the top of the chord.  The bolts are
all in direct contact with wood in the side of the hole toward the center of
the connection.  The horizontal force in the diagonal will be transferred
through wood-wood bearing into the vertical web, then through cross-grain
bearing from the vertical web bolts into the gusset.  The vertical force
will be transferred through wood-wood bearing into the chord, then through
cross-grain bearing from the chord bolts into the gusset.

The easy way to prevent this is by specifying a small gap between the wood
members.


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