Evaluation Of Response Modification Factor For Moment Resisting Frames

Abstract

Conventional seismic analysis of structure incorporates only elastic response of the structure. To understand nonlinear response of the structure, Performance Based Design (PBD) approach is widely used. PBD includes Pushover analysis i.e. nonlinear static analysis, which shows the post-elastic behaviour of the structure. IS 1893-2002 incorporates the nonlinear response of a structure considering response reduction factor (R) so that a linear elastic force based approach can be used for design. The response modification factor plays a key role in the seismic design of new buildings. However, the Indian code does not provide information on the components of R factor. The values assigned to this factor is based on engineering judgment. The study includes the calculation of value R based on different components as per ATC-19 and compares values of R for Special Moment resisting frame (SMRF) and Ordinary Moment resisting frames (OMRF) for two different seismic zones. An improvement in the reliability of modern earthquake-resistant buildings will require the systematic evaluation of the building response characteristics, which mostly affects the values assigned to the factor.