Structural response modification factors (R-Factor) relate the actual earthquake response of structures at significant yield level to the elastic response as represented by the response spectrum computed from strong-motion records. As a result, R-Factors provide a basic mechanism through which strong-motion data can be applied in the seismic design of many building types. The objectives of this research project are to assess the R-Factor concept in general, to evaluate currently available R-Factor values through the analyses of strong-motion records and building response data, and to develop guidelines for assigning and utilizing R-Factors in the seismic design of commonly used structural systems. The improvement and refinement of the R-Factor approach and the development of R-Factors for specific building types will significantly benefit the engineering community and the construction industry nationwide.
