Experimental Study On Isolation Structure Of Liquefied Natural Gas Storage Tank

Liquefied petroleum gas storage tank is an important modern industrial facility,Once destroyed in the earthquake will cause serious damage to human life and property,the consequences are extreme ly serious,So it is the most important problem for the safety design.At present,most of the domestic and foreign researches on the seismic response of LN G storage tanks are focused on theoretical analysis,The experimental study is only based on the consideration of one way and far field vibration,but less study on the vibration test of Multi and seismic isolation under near field and consider working conditions,It can not fully reflect the true ground motion response of the seismic isolation tank in various fields.In this paper,the experimental of seismic isolation study on the single direction and three direction input of ground motion for LNG storage tanks.In this paper,the geometric dimensions of the tank and the model of similarity ratio are accounted.The horizontal stiffness,horizontal yield force and damping ratio of the bearings are obtained;The compression test was carried out to obtain the vertical stiffness of the support.The seismic wave is selected according to the principle of seismic wave selection and the purpose of the experiment,a total of 5 natural waves and one artificial wave are selected.The sensor adopts ICP type acceleration(displacement)sensor and laser displacement sensor,layout according to test purpose.In accordance with the requirements of the subject and the purpose of this test to determine the 156 conditions,the number of more,more comprehensive type.According to comparative analysis of the experimental results,the comparison of the variables include: if there is no support,the ratio of height to diameter,the dimension of ground motion.After the analysis of the acceleration response and displacement response of the tank,the following conclusions are obtained:(1)When the horizontal seismic wave is input,the maximum point of acceleration appears in the center of the tank.the upper part of the tank under the condition of the isolation bearing is accelerated by a factor of 869%,while the acceleration response of the upper tank is reduced by 0.9% compared with that of the shaking table.When the 3D seismic wave is input,the maximum point of acceleration appears in the center of the tank.Horizontally,the shock absorber which absorbing effect is the best,only increasing the acceleration by 176.5%.the isolation tank amplification rate of no more than 158.8%,while the shock absorber which absorbing effect is the best reduce the acceleration of 19.7%.The damping effect of high damping rubber bearing is better than that of lead rubber bearing.(2)Near field seismic wave input.The change of the site type will affect the acceleration amplification effect of the isolated storage tank,and the different isolation bearings will change the regularity of the influence of the site classification,The general trend is that the acceleration amplification effect of the three types of sites is greater.Comparison of near-field and far-field seismic waves.The storage tank with lead rubber bearing is provided in the two kind of near field Wenchuan Wolong wave,The amplification effect of horizontal acceleration is greater than or close to the acceleration amplification effect of two kinds of far-field EL Centro wave input;The amplification effect of vertical acceleration is less than that of the latter;In contrast with the two kind of far field Taft,it is less than the latter in the three directions.The effect of the acceleration amplification effect of the tank with high damping rubber bearing is less than that in the two kind of far field under the condition of the two kind of far field.(3)Unidirectional horizontal seismic wave input.The displacement response of the tank with the isolation bearing is greatly reduced,and the upper part of the isolation bearing is similar to that of the tank.Three dimensional seismic wave input,The displacement response of the tank with the isolation bearing is also greatly reduced in the horizontal direction than that without the isolation bearing.The analysis shows that the isolation bearings are more suitable for the squat tank.In the vertical direction,the displacement of the isolation bearing tank is higher than that of the isolated storage tank.(4)Near-field seismic wave input.Setting the storage tanks of two Isolation,half or ful,in the horizontal direction,the displacement of three types of site is more than one and two sites,the horizontal displacement of isolated storage tank increases with the soil of the site.Comparison of near field,setting of lead rubber bearing and high damping rubber bearing tank,whether the volume of storage liquid is half or full pot,in the second field near field Wenchuan Wolong Wave,the horizontal displacement is less than the displacement of two-dimensional far-field El Centro wave and taft inputting.