Response modification factor for roof top deck

[tmoe]

I'm reading through ASCE7-05 trying to determine what section is most appropriate for determining lateral loading of a roof top deck that will be placed on a 4 story structure in high seismic zone (San Francisco). Was leaning toward using Chap 15 Nonbuilding Structures and using " inverted pendulum type structures" as my structure type which gives R=2. Does anyone know if decks are specifically called out in the code somewhere??

Thanks

 

[JAE]

Is this deck like a separate story some distance above the roof or is it closer to the roof - more like an appendage located just above the roof?

Seems like if it is significantly higher than the roof you almost need to treat it as a new story and the R would be based upon the lateral bracing method of the deck structure.

If it is closer - more like 1 or 2 feet above, I would think it would be more of a "finish" or cover over the roof and I might use a component force (rigid vs. flexible) in ASCE 7-05,
Table 13.5-1.