structural insulated panel roof diaphragms

huangyhg

structural insulated panel roof diaphragms
does anyone out there know where i can get some guidance on diaphragm strength of structural insulated panels (sips) used to clad a timber-framed roof?
i have heavy timber (likely 12x16 or bigger) tied-rafters 13' o.c. with a 8 on 12 pitched gable roof.  building is 40'x80'. i would like to span the sips between the rafters and have no purlins, or ridge beam, between the timber rafters.  essentially the sips would simple-span between the rafters and their only connection would be only to the top of the timber rafters and a continous timber around the roof perimeter, which supports the wall infill studs between the timber frames and serves as the diaphragm chord members.   
any help would be appreciated.
thanks.
a significant amount of research was performed on this topic at virginia tech.  in particular this dissertation by david carradine would be of use:
check out the icbo reports for different manufacturers; r-control or premiere have published diaphragm & shear values.
thanks for the replies.  i will look into the va tech and icbo reports.
thanks again