Most building structures today are designed using the response modification factors (R-factors) given in the code for different types of structural systems. This paper examines whether ductility-based modifiers for structural members (m-factors), recommended in FEMA-356 (Prestandard and Commentary for the Seismic Rehabilitation of Buildings, NEHRP 2000) are more representative of true demands and, therefore, a better alternative to R-factors in seismic design. Two case studies are summarized in this paper. The selected buildings were analyzed using linear static, linear dynamic, and nonlinear static procedures. Comparative studies between the global R-factor and the response-based m-factor indicate that the use of m-factors is more rational since it includes considerations of material behavior and is more representative of deformation demands at story levels. Additionally, mean estimates of m-factors were found to correlate reasonably well with mean demands computed using nonlinear dynamic procedures.
Conference Dates: July 21-25, 2002
Conference Title: Proceedings of the 7th U.S. National Conference on Earthquake Engineering
Pub Type: Conferences
dynamic analysis, earthquake engineering, nonlinear analysis, performance-based design, response modification factors, seismic design