Seismic reduction factor evaluation and its components for steel buildings undergoing nonlinear deformations

Abstract

The force reduction factor (R) and its components for steel buildings are evaluated in this study. The R factor for single-degree-of-freedom models produces non-conservative designs. The global R values can be very different than the local ones. The contribution of damping to R is much more uniformly distributed and different than that of yield, implying that the latter should not be expressed in terms of viscous damping. The value of 8 specified in the codes for R is justified only for low-rise buildings and global parameters, if viscous damping is considered. If damping is not considered, this value cannot be justified in any case, a value of 6 is recommended.