Michael Bryson wrote:
< AISC Seismic Provisions for OC braced frames, section 14.2 and 14.5, implies that you cannot have a tension only bracing system for buildings higher than three stories. Is that correct? What about if you have the first three stories concrete shear walls and the fourth story braced? >
You should be able to analyze the structure separately, a 3 story concrete shearwall building with the reactions from a 1 story CBF building applied to the top of the concrete building per UBC 1630.4
Gerard Madden, P.E.
Middlebrook + Louie, Structural Engineers
71 Stevenson Street, Suite 2100
San Francisco, CA 94105