I. Introduction
To make the structure complete the specified task in its service period safely and reliably, reliability analysis has been a key part of structure design. A variety of reliability analysis methods have been explored, intended for calculating the failure probability. The Monte Carol Simulation (MCS) [1], [2] is a direct method to reach the failure probability. However, it requires the entire population to be calculated to obtain the failure probability, which is computationally expensive. To reduce the computational expense, surrogate models were introduced to approximate the calculations, including the classic polynomial response surface [3], the support vector machine [4], [5], the neural networks [6] and Kriging [7], [8].