Study On Seismic Behavior Of Anchored Storage Tanks With Random Initial Geometric Imperfections

Along with our country economy sustained and rapid development,oil demand is rising year by year.Relevant national statistics show that China's net oil imports has exceeded the United States in the past year,becoming the world's largest oil imports,the external dependency of oil is as high as 64.4%.Faced with such a huge amount of imports,our country has beginning to prepare to build the national petroleum reserve base since the 12 th five-year plan,and the 13 th five-year plan emphasizes to further promoting the construction of the second and third phase of construction of oil reserves.The oil storage equipment which has been built is most of cylindrical vertical oil tanks,witch are more constructed in the seashore,and being prone to damage under earthquake load.At the same time,the damage of oil tanks can also cause oil spill,fire and other secondary disasters.Besides,the diameter ratio of oil tanks is usual more than1/1000,and wall thickness is small,light weight,the oil storage tank is easy to generate local geometric defects during the process of processing and using,which can result in local bumps,non-roundness and vertical degree of random geometric exceeding the quota of code.There,when researching the seismic reliability of the random initial geometric defect storage tanks under random seismic,the related standards and literature make too much simplification.For that,the additional mass method will be used to study the seismic reliability of the oil storage tank with random initial geometric imperfections under random earthquake load.Firstly,the theory of fluid mechanics and reliability is introduced.On the basis of that,the fluid-structure interaction problem is solved by the method of decoupling thefluid-structure interaction.And the area of the added mass unit is acquired by using Helen Keller equation.Then,based on the ABAQUS secondary development of user unit subroutine,the application of the additional quality of the oil storage tank under the deformation condition is realized,and the dynamic water pressure is more accurately simulated.After that,the simplified model of the oil storage tank is established to solve the structural response under different peak acceleration.And then,the limit state of the simplified oil tank model is compared with the limit state specified in API650,JIS B8501 and GB50341-2014 to determine the buckling limit state equation of the oil storage tank.Finally,based on the non-stationary random earthquake effect of seven and eight degree,considering the randomness of the material and the self-weight of the oil storage tank,the seismic reliability of oil storage tanks with random initial geometric imperfection is solved.The results show that random initial geometric imperfection can significantly reduce the seismic reliability of the oil storage tank.With the increase of the seismic action,the influence of the same random initial geometric imperfections on the seismic performance of the oil storage tank is gradually increased.