UNIFORM HAZARD SPECTRA BASED ON PARK-ANG DAMAGE INDEX

Abstract

The primary emphases in the performance-based seismic design (PBSD) philosophy are in the accounting for uncertainties in seismic demand/capacity and in the better quantification of seismic damage using suitable inelastic damage parameters. Uniform hazard spectra (UHS) provide probabilistic information regarding a seismic demand on a single degree oscillator for a specific site. UHS are very good tools for probabilistic hazard estimation as intended in PBSD. In the present work, UHS are generated for Park-Ang damage index of an elastic-perfectly plastic oscillator. Park-Ang damage index takes into account the effects of both displacement ductility demand and hysteretic energy demand in low-cycle-fatigue, and therefore is a demand parameter suitable for PBSD. The UHS are generated for a specific site using artificially generated ground motions. Two types of UHS plot are illustrated. A correlation between the probability of exceedance (of certain target damage index) and stated level of structural capacity is also established. Information provided by the UHS are proposed to be used, with the aid of equivalent systems, in the development of a reliability-based seismic design framework considering Park-Ang damage index as the seismic demand parameter.