| LNG(Liquefied Natural Gas)is mainly composed of methane, As we all know it is a kind of efficient and clean fuel. With the development of production and long-distance transportation technology, it may change global energy landscape in the near future. Many large LNG storage tank have been established as the receiving terminal, But once destroyed, LNG tank is likely to cause leakage and a fire, resulting in huge economic losses and casualties. The LNG tanks closed to the fire have to be bear with high temperature.To void the chain reaction, it has very important significance to research the safety of storage tank in high temperature conditions.In this paper, the basic concept of reliability was introduced firstly, which was the basis of reliability analysis. Selecting a reasonable analysis was very important to the accuracy results of analysis. Then, the parametric finite element model of LNG tank was established, and system reliability analysis was carried out under high temperature. The effect of high temperature on the mechanical properties of the reinforced concrete structure was taken into account in thermal-structure coupling analysis. The failure path of tank wall was searched out, and the destruction of wall of tanks composed by the top and the bottom of the tank wall, this two fail model was considered as series system, which was composed of a plurality of element. With the definition of random variables and failure criterion, response surface method was used to fit the function of different failure element, and the reliability index and the design checking point were solved by JC method. By killing the failure element, the follow-up element was found by recalculating that made the stress redistributed.By this way the failure path could be found, and then an equivalent reliability index of the failure path would be work out by using equivalent linearization method. In the end, the range of system reliability of tank was calculated respectively by using boundary estimation. |
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