低温作用下大型LNG预应力混凝土储罐力学分析

Low Temperature Analysis of LNG Prestressed Concrete Tank for Spill Conditions

大型LNG预应力混凝土储罐储存超低温的LNG，对结构的安全性和可靠性提出了更高要求。给出了低温作用下材料的本构模型；借助于ANSYS有限元软件，以16万立方米混凝土储罐为例，对低温下混凝土外罐的温度场和内力分布进行了深入的研究计算，给出了低温作用下混凝土外罐的温度场分布，并针对高低温并存的工作状态下结构内力进行了计算。结果表明：超低温作用下LNG储罐温度分布由内而外呈线性分布，罐壁的温度分布比较均匀；在承台、罐壁以及罐顶的连接部位，为避免由约束作用产生的负弯矩以及低温拉应力产生的裂缝，应在混凝土外罐中合理配置预应力钢筋和热保护角等保冷结构。研究成果对于提高我国大型LNG预应力混凝土储罐的设计水平具有一定的指导意义。

Cryogenic LNG is stored in large prestressed concrete tank, which needs more requirements for safety and reliability for its structure. Constructive relations of materials under cryogenic conditions is given. Finite element software ANSYS is used to study the temperature and stress profile of a prestressed concrete outer tank for 160,000m^3 LNG storage tank. And structural stress in high and low temperature of operation conditions is studied. The result shows that temperature distribution is linear from the inside to the outside of the LNG tank, while it is uniform. Larger minus bending moment exists in the connection of the cap ,wall and roof for the constraints. In order to reduce the tensile stress and to avoid cracks, prestressed bar and thermal comer protection should be allocated in concrete outer tank. Study achievement is meaningful for improving the engineering level of large LNG prestressed concrete storage tank in China.