ASCE 7 seismic shear walls with concrete frame; dual system or not?

[RFGMT]

Consider a reinforced concrete building frame (beams and columns) with concrete shear walls (between and integral with the columns) designed for seismic resistance per ASCE 7-05 in SDC C or worse. Can this system be classified as a "B. Building Frame System" per Table 12.2-1 or MUST it be classified as a "D. Dual Systems with special moment frames...", or "E. Dual System with intermediate..." Systems D and E will require a more complex analysis particular for higher SDCs. I do not need a "dual system" but I am not sure if "B" can be used due to the presence of the moment frame. Can anyone site a reference that clarifies this? I have not found one.

Thanks.

 

[ishvaaag]

You can find an example of what is thought to be a Building Frame System iat chapter 4 of

Design of Concrete Buildings for Earthquake and wind forces
S.K. Ghosh
August W, Dimel, Jr.
Portlan Cement Association 1992

Essentially "a complete frame providing support for gravity loads, with resistance to lateral loads provided by shearwalls. Since beam-column frames are not part of the lateral load resisting system, they do not require special detailing."

Having columns at the ends of the shearwall is no obstacle to consider the system within this classification. There are figures in the chapter that prove so. Gravity loads are assigned on a tributary basis to the shearwalls as well, and compatibilization of the "brought to expected value" displacement must be ensured for the gravity-only parts of the structure, i.e., the gravity frame and members need be stable with such displacements in the structure.