new openings in existing wood diaphragm

huangyhg

new openings in existing wood diaphragm
is there a good reference for the design of openings in an existing structure (or new for that matter) to account for the shear transfer around the opening?  this particular project is in seismic design category d
i believe that the american plywood association has some good publications regarding wood diaphragm design.  
really nothing fancy about this - just basic diaphragm design.  is this a roof or floor diaphragm?  is this for an ac unit, a skylight, an atrium...???
you may just need to increase the nailing or you may need to design and add new drag struts, depending on the opening size with respect to the size of the diaphragm.  
hopefully you will not have to do a new lateral analysis for the entire structure, but that may be the case...considering the age of the structure and you are modifying the structure.  it may have to comply with current codes depending on the level of the structural changes.   
mike mccann
mmc engineering