Study On Static Strength And Dynamic Response Of The Large Oil Storage Tank

Along with the large scale of oil storage tank, the potential risk of tanks is increasing. The fracture accident of tank will cause a great loss. In order to ensure the safety of large oil storage tank, further research to the static strength and seismic response of tank are carried on.With the support of 'the safety analysis of the 15×10~4m~3 oil tank, the static stress analysis and test of tank were conducted, and then the dynamic response of tank was investigated simply. The research works of the thesis mainly include:(1) In order to account for the effect of bottom plates on the second shell course in the stress calculation of large oil storage tanks, a new stress calculation methodology based on the theory of combined cylindrical shell was proposed. In this methodology, the first shell course was assumed as a short cylindrical shell and other shell courses as long cylindrical shells. The bottom plates were modeled using coupled flexible and rigid foundation beams. Stress formulas of the shells and bottom plates were derived based on the solution of a combined model of the bottom plates, the first shell course and the second shell course.(2)The axisymmetric finite element method was proposed to calculate the whole stress of tank. This method applied the contact element to simulate the interaction between foundation and tank bottom. There is incomplete penetration in the shell-to-bottom fillet welds. The interaction between bottom and shell in incomplete penetration also could be simulated by the contact element. It indicated that the influence of incomplete penetration is up to 60mm. The axisymmetric finite element wasn't suitable for shell openings stress analysis, so the submodel method was adopted.(3)The stress test was conducted during water pressure test of the 15×l0~4m~3 oil tank. A lot of test data was collected by stress test. The result of test value, theoretical value and FEM value match together very good, which indicated these methods were reliable.(4)The vibration of large oil storage tank was conducted by there-dimensional finite element method. The influence of density and height of liquid in tank were researched. With the increment of density and height of liquid, the natural frequency of liquid-solid interaction vibration is down.(5)The earthquake response of the 15×10 m~3 oil tank was simulated by finite element method. The distribution and variation of hydrodynamic pressure were researched. Therefore, the sloshing of free surface was investigated preliminarily too. The top of tank appeared negative pressure in earthquake that may cause diamondshape buckling.