Structural Safety Evaluation by Means of Fuzzy-probabilistic Approach

The evaluation of the safety level in concrete structures should be done considering the stochastic behavior of main involved parameters not only in ultimate conditions but also in serviceability and durability ones. In fact, particularly in concrete structures, the large variability of fundamental mechanical parameters, may give rise to important deviations from the behavior expected if a deterministic approach is used. On the other hand it is well known that the probability density functions and their parameters cannot be defined univocally. To overcome this problem the fuzzy­ probabilistic theory may be used in processing stochastic parameters, consideration taken to the fuzzy nature of their character. In practice the probabilistic level 3 method may be used but, due to the fuzzy nature of involved variables, the analysis produces a fuzzy-probabilistic result. The above procedure is applied to a bridge prestressed beam, to evaluate its behavior in serviceability condition, with particular attention to the crack formation limit state.