what is blocked diaphragms, what is unblocked diaphragms

huangyhg

what is blocked diaphragms, what is unblocked diaphragms?
i am looking at ibc-2006, table2306.3.1 (page445), can anybody please help me to understand what configuration is called blocked diaphragms, what configuration is called unblocked diaphragms?
thanks a lot
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a blocked diaphragm is one where all panel joints fall on framing or blocking.  if you have floor joists space 16" o.c. with 4x8 sheets of plywood running perpendicular to the joists you have an unblocked diaphragm because you have unsupported panel edges between the joists.
if you add blocking between the joists so that all panel edges are supported you have a blocked diaphragm.
buy a copy of don bryer's book "design of wood framed structures".  don's book has a lot of information about diaphragms and shear walls.  it covers such things as shear walls with both vertical and horizontal offsets.  
rarmbj:
thank you very much.