【作者】 林杨；

【导师】 杨建江；

【作者基本信息】 天津大学 ， 结构工程， 2012， 硕士

【摘要】 大型LNG储罐的组成为:预应力混凝土外罐;承台;穹顶;吊顶;绝热层;9%镍钢内罐以及桩基础。正常操作条件下,全容式LNG储罐的钢内罐保存超低温液体,外罐承受来自于外罐顶的荷载,保存内罐泄漏出的超低温液体,并将泄漏液体气化而产生的气体有控制地排出。本文通过ansys有限元分析软件建立了大型LNG储罐的桩、土以及上部结构整体三维模型,基础选型分为三种:低承台、高承台(承台架空1米左右)、高承台加橡胶隔震支座。各种模型的计算工况均包括:运行基准地震(OBE)、安全停机地震工况(SSE)的加速度峰值条件下,结构在EI-centro波、天津波以及人工波作用下的响应。计算分析了结构在地震作用下,加速度、位移、倾覆力矩以及底部剪力随时间变化的结果。通过计算得出的结果可以看出,不同的桩基形式对上部结构的影响是不同的。在地震作用下,高、低承台的地震响应差别不大,而隔震体系对上部结构的地震响应有着很大的减震效果,虽然增大了上部结构的整体位移,但是大大降低了地震的加速度响应及应力值。所以考虑高承台加隔震支座的基础形式是更为合理的。对于三种不同的地震波形,模型对EI-centro波的地震响应是最大的,而天津波和人工波的地震响应较小,通过各项地震响应值的对比,给出了各地震波作用下的隔震效率。对桩身的受力特性也进行了分析。从文中的分析结果可知,选择高承台加隔震模型对上部结构的地震响应及桩身的受力都是有利的。更多还原

【Abstract】 A Low Temperature LNG Storage Tank consists of external wall of prestressed concrete, pile cap, roof, insulation, inner wall of 9% Ni steel and pile foundation. In normal operation condition, the inner wall contains liquid of extremely low temperature, the external wall bears the load transferred from the roof. The external wall also contains divulged liquid and gas, then discharges them in a controllable method.The integrated model of LNG tank was established by Ansys, including pile, soil and upper structure. Three different foundation types, which were low cap, high cap and high cap with rubber isolation, were established respectively. The working condition of these models included operation base earthquake(OBE) and safety shutdown earthquake(SSE). Both of them were analyzed under three different earthquake waves. The seismic responses of the models, including acceleration, displacement, overturn moment and bottom shearing force, were analyzed and discussed. The isolation efficiency was discussed by comparing the responses of these models. The stresses of piles were also analyzed.From the calculating results, it is found that different foundations result in different earthquake responses. There are little differences in the responses of low cap model and high cap model. But isolated model hugely reduces the responses of upper structure though it increases the displacement. The responses under EI-centro wave are higher than that under Tianjin wave and artificial wave. Conclusions are drawn that high cap with isolation model will effectively reduce the seismic responses of upper structure and the stresses of piles.更多还原