/ '| From the Desk ()_________)
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(__) Dennis S. Wish PE
This is an interesting question. My opinion is that this is a transitory zone
and the exact location of change from a blocked diaphragm to an unblocked
diaphragm is only calculated and not exact. The fact that the panels are
lapped (load case 1) for example, would place both boundary and field nailing
in the same line of shear.
I would think that that the change in spacing and addition of blocking should
occur in the zone of lesser shear for the panels that overlap this imaginary
The real case will be how it is interpreted by the contractor in the field -
more than likely he (or she) will change the spacing of the nail to the
critical side of the zone line.
I would assume that it would be save to consider the imaginary line of zone
change to be the blocked line and make it boundary nailed for conservativism.
In reality, the load is proportionally changed and therefore the change at
the transition zone would seem less critical than a few feet further on the
I hope this addresses your issue.
Dennis S. Wish PE
Structural Engineering Consultant