A hybrid reliability approach for structure optimisation based on probability and ellipsoidal convex models

In this paper, a new reliability analysis technique is developed based on a hybrid uncertain model, in which the probability and ellipsoidal convex models are used to quantify the uncertainty. Apparently, a complex nesting optimisation problem will be involved in this hybrid reliability analysis and the traditional optimisation method will lead to extremely low efficiency. To alleviate the computational burden, an efficient decoupling strategy is developed to solve the nesting optimisation problem. Based on this decoupling strategy, an equivalent single-layer optimisation model with only random variables can be obtained and the sequential quadratic programming method is adopted to directly solve this equivalent model. Two numerical examples and two engineering problems are investigated to demonstrate the effectiveness of the present method.