Earthquake-resistance Analysis Of Large Unanchored Oil Storage Tank

The oil storage tank is the storage device of the energy system in the lifeline system.It is of great value to the research of earthquake resistance.In this paper,the finite element numerical simulation analysis method is adopted in order to study the earthquake resistance of the oil storage tank.The finite element model of the tank is established in ADINA software.Firstly,the static and dynamic characteristics of oil storage tanks are studied by static analysis and modal analysis.Subsequently,considering the fluid solid coupling effect,the ground motion of the tank is studied by the elastic time history analysis.And then,the influence of liquid level sloshing,liquid density and depth change on tank body is compared and analyzed.Finally,elastoplastic analysis is used to study the buckling failure of the tank wall under frequent earthquakes and rare ground motions.Research shows:(1)The natural vibration period of the empty tank is 0.64s;the shaking period of the full tank liquid surface is 13.18s;the fluid-structure interaction vibration period of the tank wall is 1.78 s.It shows that the tank wall is rigid.The liquid increases the flexibility of the structure,resulting in longer interaction vibration cycles.The depth of liquid has little effect on the low order modal shape of coupling vibration.The deeper the depth of liquid is,the larger the coupling period of the tank is,but the smaller the shaking period of the tank liquid surface is.The larger the liquid density is,the larger the coupling period of the tank is.(2)The fluid-structure interaction has a lagging effect on the peak response of tank wall.The elastic analysis shows that: The equivalent stress and horizontal lateral displacement of tank wall increase first and then decrease along the fluid-structure interaction area.And there is an increasing trend of ground motion response at the top without liquid.The most unfavorable position of tank wall dynamics is in the middle and lower part of the tank wall.The acceleration of the seismic wave has magnification effect on the tank wall.The peak acceleration of the tank wall first increases,then decreases and then increases again along the height of the tank wall.(3)Different seismic waves have different influences on the earthquake response of oil storage tanks.The effect of vertical seismic action on tank wall stress and horizontal lateral displacement is more obvious than the effect of horizontal seismic action.The depth of liquid storage and the density of liquid storage only affect the tank wall stress and horizontal lateral displacement in the fluid-structure interaction region.With the increase of liquid depth,the stress and displacement increase.At the level of the liquid level to the top of the tank,it tends to be the same value.The larger the liquid storage density is,the smaller the stress and displacement of the tank wall are.(4)Elastic-plastic analysis shows that: In the multiple earthquake,some nodes of the tank wall will yield material strength at some time.The tank wall is local yield,while the whole structure will not buckle and the tank can work normally.In the rare earthquake,the wall of the tank will buckle and the stress will redistribute.The most unfavorable position of tank wall dynamics will move down after the tank wall buckles.