Fuzzy-bayesian approach to reliability of existing structures

Classical reliability has significantly enhanced the ability of engineers to assess the safety of constructed projects. It has been shown that Bayes' theorem is an effective tool in updating prior probabilities when the value of a random parameter is known. However, the preceding theorem usually fails to adequately address the uncertainties of the subjective parameters (such as "the connections are good") that are associated with structural evaluation. It has been demonstrated that these parameters can be significant to the overall safety assessment. With the introduction of fuzzy-set theory, it is possible to quantify the qualitative evaluation and incorporate it into the safety assessment. This paper presents an algorithm to compute the posterior probability based on visual inspection of structural components by incorporating fuzzy-set theory into Bayes' theorem. The results based on two examples—a reinforced concrete beam and a structural frame—showed that the fuzzy-Bayesian approach is a viable enhancement to the safety assessment of existing structures.