The R factors first proposed were based largely on judgment and qualitative comparisons with the known response capabilities of relatively few seismic force resisting systems in widespread use at the time. Since then, the number of structural systems addressed in seismic codes has dramatically increased. As a result, the seismic response characteristics of many systems, and their ability to meet seismic design performance objectives, are both untested and unknown.In an attempt to address these issues, the Applied Technology Council (ATC) was commissioned by Federal Emergency Management Agency...
The R factors first proposed were based largely on judgment and qualitative comparisons with the known response capabilities of relatively few seismic...