SAFETY INDEX CALCULATION USING INTERVENING VARIABLES FOR STRUCTURAL RELIABILITY-ANALYSIS

This paper utilizes the intervening design variables concept for struc tural reliability analysis. This procedure was traditionally used in s tructural optimization, whereas this work applies to problems having s tochastic information. The present algorithm is on the basis of a safe ty index algorithm present in Ref [1] [L. P. Wang and R. V. Grandhi, E fficient safely index calculation for structural reliability analysis. Comput. Struct. 52, 103-11 (1994)], which utilized the nonlinear appr oximation of performance function in the original space of random vari ables. The proposed algorithm further develops this procedure by (i) i mplementing the adaptive nonlinear approximation of performance functi on in the standard normal space of random variables, (ii) using an imp roved intervening variable procedure for more accurate approximation, and (iii) adding an additional convergency check on safety index calcu lation using approximate gradients. The efficiency and robustness of t he proposed algorithm are demonstrated by several examples with highly nonlinear, complex, and explicit/implicit performance functions.