DISPERSION REDUCTION OF SEISMIC NONLINEAR RESPONSES OF A 3 STORIES ASYMMETRIC REINFORCED CONCRETE FRAME

Performance-based design method which enables designers to evaluate various performance levels of a structure for a given hazard level, consists of four steps: hazard analysis, structural analysis, damage assessment and loss estimation. The structural analysis responses are formulated by statistical analysis of the results of the set of non-linear time-history analyses of typical structure for the expected earthquakes. Although mean inelastic displacement ratios are very important, it is equally important to quantify its scattering and dispersion which usually display large record-to-record variability. For a given level of confidence, it is desirable to find an efficient method which can reduce the dispersion in the results with using fewer records. This paper proposes a method for dispersion reduction of nonlinear seismic response resulting to more reliable loss estimation. The method has been applied on a 3 stories asymmetric reinforced concrete structure. The results of a comprehensive statistical study of aleatory uncertainty distribution in structural response are presented. These uncertainties are computed for different levels of strong motions representing the seismic characteristics of a predefined scenario. The study is based on a set of time histories recorded on near-field region. Inelastic displacement ratios associated with the median values are presented and special emphasis is given to the dispersion of responses. Dispersion of the responses is monitored with emphasizing on “scaling parameters”, “level of ground shaking ” and “damage measure”