LNG储罐单层球面网壳结构动力特性分析

Analysis of Structural Dynamic Properties of LNG Storage Tank

为研究LNG储罐穹顶单层网壳在地震载荷作用下的动力特性,通过3D3S软件建模并借助有限元分析软件ANSYS对单层网壳进行模态分析和地震时程分析,得到结构自身振动特性和动力响应规律。结果表明:穹顶网壳相邻两阶固有频率相近,网壳变形左右对称,后期以整体变形为主。地震波的形态和频率对结构节点位移时程曲线和杆件轴力时程曲线的形状影响较大,结构在人工波作用下动力响应最大,应该选用多条地震波对网壳结构进行包络分析;矢跨比在前10 s相同地震激励下对结构动力响应影响较大,矢跨比为5/36时结构变形最小且最为稳定;整体结构节点位移明显大于单独网壳结构,设计网壳结构时,应该考虑下部结构对网壳动力性能的影响。

In order to study the dynamic characteristics of the single-layer reticulated shell of the LNG storage tank dome under seismic load,3D3S software was used for modeling,and the finite element analysis software ANSYS was used for modal analysis and seismic time history analysis of the single-layer reticulated shell,so as to obtain the vibration characteristics and dynamic response law of the structure itself.The results show that the natural frequencies of the two adjacent orders of the dome reticulated shell are similar,and the deformation of the reticulated shell is symmetrical.The shape and frequency of seismic waves have a great influence on the shape of the time-history curve of the node displacement and the time-history curve of the axial force of the rod.The dynamic response of the structure is the largest under the action of artificial waves.Multiple seismic waves should be selected for envelope analysis of the reticulated shell structure.Under the same seismic excitation in the first 10 seconds,the vector span ratio has a great influence on the dynamic response of the structure.When the vector span ratio is 5/36,the structural deformation is the smallest and the most stable.The node displacement of the whole structure is obviously greater than that of the single reticulated shell structure.The influence of the substructure on the dynamic performance of the reticulated shell should be considered when designing the reticulated shell structure.