INTERVENING VARIABLES AND CONSTRAINT APPROXIMATIONS IN SAFETY INDEX AND FAILURE PROBABILITY-CALCULATIONS

The emphasis of this paper is on developing suitable intervening varia bles and constraint approximations for structural reliability analysis . Traditionally, these procedures are used in structural optimization, whereas this research work adopts these concepts to safety index and failure probability computations. The use of these concepts enables th e development of an efficient and stable iteration algorithm for ident ifying the most probable failure points (MPPs) of the limit state func tions. An approximate second-order failure probability is calculated a t this MPP with no extra computations of the limit state function and gradients. The efficiency and accuracy of the proposed algorithm are d emonstrated by several examples with highly nonlinear, complex, explic it/implicit performance functions.