Reliability study of a containment shell

Computational time needed for reliability analysis of realistic structural problems as a rule is very high. Improvements in efficiency are critical to allow solution of large realistic problems. The reliability analysis is usually performed using approximate First Order Reliability Method (FORM). Iterative solution procedures of FORM require extensive design sensitivity computations of high accuracy. The design of realistic structures requires computer-based numerical procedures, such as finite element analysis. The design sensitivity gradients are not explicitly available in terms of design variables. The most intensive computational task of design sensitivity computation should be carried out by highly efficient and accurate methods such as discrete design sensitivity analysis. This paper describes requirements for design sensitivity information for reliability analysis. The way of coupling reliability computation with discrete AVM and DDM methods of design sensitivity analysis is pointed out. A computational program developed for layered concrete shells allows one to solve large realistic reliability problems. The reliability study of an RC nuclear containment shell is carried out. Reliability studies show which of the parameters have the highest impact on the reliability of the vessel.