engleski

One Approach to Limit State Design

The design process is clouded with uncertainties arising from errors in idealisation and incomplete information. Therefore, assurance of absolute prevention of failure is a difficult task, and risk must be considered the design procedure. Thus, probabilistic approach to design has been widely accepted in engineering practice. It is based on identification of all variables influencing the expression of the limit state, deriving their probability functions, and comparing the probability that the limit state criterion is not satisfied to limit probability previously accepted. An inventive alternative to probabilistic reliability theory has appeared recently - the possibilistic theory of reliability, which uses a new confidence measure: possibility of failure defined by means of fuzzy logic, as a possibility that safety margin be negative or zero. The main advantage of possibilistic approach to design is the fact that determination of reliability indicators (failure possibility and possibility reliability index) is much easier than in the probabilistic approach. Hence, the probabilistic approach generally requires optimisation of a multivariate function, while the possibilistic approach reduces the study to the optimisation of the variable function.

probabilistic theory; possibilistic theory; design point; limit state function

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