Evaluation Method of Statistical Uncertainties for Safety Index Based on Confidence Ellipsoid

摘要

This paper deals with the problem of statistical uncertainties of safety index. Though a second moment safety index is widely used as a safety index for a probabilistic design code, it is impossible for this index to avoid to include intrinsically statistical variations since the random parameters are estimated only from the obtained field data or imperfect information. In this paper, the new measures for statistical uncertainties of safety index which is proposed as a confidence region is around the design point with the confidence level. These confidence regions of safety index are derived from an ellipsoid on super plane whose region corresponds to the value of confidence level. This paper shows that region for safety index can be mapped as the internal region of an ellipsoid on super plane. Therefore the region called as confidence ellipsoid.