Practical method of reliability-based condition assessment of existing structures

The continued use of existing structures is one of the important factors for achieving sustainable society. In order to assess such structures for continued future service, simple and practical tools need to be developed for evaluating the time-dependent reliability and performance of the structures. Authors have introduced the concept of resistance reduction factor with which a time-dependent reliability problem can be approximated as a time-independent one. This paper describes the improved method to estimate a factor, with which the inverse of cdf and extremely accurate numerical integration is no longer necessary. On the course of the analysis, it is found that the resistance reduction factor is heavily dependent on the type of cdf of the principal load intensity. Classifying the cdf's according to the classification of a parent distribution of extreme value distribution, a revised formula for resistance reduction factor is proposed. The accuracy of the method is investigated using numerical examples.