Reliability analysis of stiffened tank-roof stability with multiple random variables using minimum distance and Lagrange methods

Based on the reliability and buckling analysis of the steel tanks with a stiffened dome-roof, a mathematical model with multiple random variables was established and a new method for calculating and analysing the reliability and stability of the tank-roof by minimum distance and Lagrange formulae is provided. The analysis result of the tank as an engineering example by the proposed method shows that the thickness of both dome-roof-plates and stiffened ribs would affect the reliability of the tank-roof under different external loads. It is demonstrated that decisive factors affecting tank-roof reliability may be analysed such as: material thickness and external load. A reliability assessment is also needed performed to prove the correctness of both model and method. The assessment results were consistent with those from the engineering example. A baseline, reference method, for tank design and operation is thus proposed.