DUCTILITY REDUCTION FACTOR OF MDOF SHEAR-BUILDING STRUCTURES

In this paper, the results of recent studies on inelastic seismic response of MDOF shear-building structures are presented. In the last few decades, the concept of response modification factor R has been introduced and developed to account for inelastic nonlinear behaviour of structures under earthquakes. In this paper, an attempt has been made to adjust and extend this concept through introducing a modifying factor R_T. This factor is used for dynamic analysis of MDOF structures, including the calculation of inelastic response spectra. Sensitivity analysis was carried out to identify the parameters that have influence on R_T. It has been demonstrated that R_T is predominantly a function of number of stories, and accordingly a relationship has been suggested. Finally, an approximate approach has been developed for evaluating the seismic strength and ductility demands of MDOF structures.