09-10-2014, 02:30 PM
The conventional approach of obtaining the inelastic response spectra for the aseismic design of structures involves the reduction of elastic spectra with the help of strength reduction factors (SRFs). SRF is considered to primarily depend on the initial time period of the single-degree-of-freedom (SDOF) oscillator and the ductility demand for the ground motion. This study proposes a preliminary scaling model for estimating the SRFs of horizontal ground motions in terms of earthquake magnitude, strong motion duration and predominant period of the ground motion, geological site conditions, and ductility ratio, with a given level of confidence. The earlier models have not considered the simultaneous dependence of the SRFs on various governing parameters. Since the ductility demand is not a complete measure of the cumulative damage in the structure during the earthquake-induced vibrations and since the information on available ductility in the system is presently ignored, the existing definition of the SRF is sought to be modified with the introduction of damaged-based SRF