Time-varying response surface method for high-temperature structural reliability analysis using copula

For the high-temperature structure, there exists correlation between the thermal stress and thermal intensity in most cases because of the two-sided effects of temperature. This paper proposes a time-varying response surface method considering correlation between the structural response value and structural response threshold based on Copula models. Firstly, the time-varying model of structural response value is developed by incorporating the interaction between basic variables and time variable into the quadratic response surface method; Secondly, the time-varying model of structural response threshold is determined based on the intermediate variable of temperature; Thirdly, the proper Copula function is selected using simulation data; Finally, the structural reliability estimation method is given when basic variables are distributed normally. The result of case study indicates that the negative correlation leads to the decrease of reliability, and with the increase of thermal stress, the difference of reliability between the correlative and independent situations becomes larger.1