Analysis Of Dynamic Characteristics And Vault Stability Of 10000 M~3 Atmospheric Pressure LNG Tank

LNG is a kind of green energy.With the continuous development of LNG industry,LNG storage tank's volume is increasingly large.Because of storing low temperature,flammable and explosive medium,once LNG storage tank was destroyed,a large number of flammable liquid leakage and fire,will cause devastating secondary disasters and serious damage to the national economy.In this paper,the seismic performance of a 10000 m~3LNG tank and the stability of the vault were studied to ensure the safety and reliability of the tank structure.The finite element model of storage tank was established,in which the contact connection between tank walls and pearlite,contact connection between inner tank bottom and ground glass brick,liquid solid coupling were taken into consideration.The vibration characteristics of the tank was analyzed and the response spectrum analysis of the OBE and SSE seismic loads was carried out.It reveals that the external tank can increase the natural frequency of the system.Higher stresses occurs at locations such as the connection coner of inner tank bottom and wall,the connection of anchor belt to the inner and outer tank wall,and the connection between outer tank wall and the vault.The inner tank is more vulnerable to damage of the earthquake load due to its uplifting.The stability of the vault is analyzed with the condiseration of both structure and load correlation.In the structural correlation analysis,the effect of the real constraint of tank wall and the simplified model constraint(full constraint,axial and circumferential constraints)on the stability of the arch was discussed.The nonlinear critical load factor of the real constraint is 11.42%lower compared with the full constraint model,which indicates that the relative structure shoulb be included in the FEA model for its real constraint to yiled more reliable stability response of tank vault.The influence of tank wall load on the stability of the vault was discussed in the load correlation analysis.The stability of the vault is also affected by the load of the correlation structure and the buckling load factor is decreased with the increase of the correlation structure load.The buckling load factor under the wind load,external pressure and the SSE earthquake load was about15.61%lower than that with the complete FE model but without tank wall loads,and about22.45%lower than that of vault only FE model with full constraints.In this paper,a new method for stability analysis of large tank vault is presented.With the finite element model of vault and tank wall constrained at the bottom,the buckling mode is obtained by the engivalue buckling analysis with the real vault loads only,which is used for the initial defects of the vault.Then two load steps are imployed in the folowing nonlinear stability analysis,namely only the tank wall loads are applied first to catch the futher deformation of the defect including structure,then the vault loads with higher enough load factor are aplied to search for the buckling load of the vault.