Research On Seismic Response Performance Of LNG Tanks With Paraments Of Isolated Bearing In Near And Far Field Conditions

LNG tanks may be damaged by earthquakes,and secondary disasters are particularly serious.How to ensure the safety of large LNG tanks under earthquake is an issue of increasing concern in the engineering community.The application of base isolation technology is to increase the seismic resistance of LNG tanks.Performance offers a new way.The current theoretical research focuses on the seismic and seismic isolation performance of LNG tanks under far field earthquakes.There are few studies on the seismic response performance of LNG tanks under the influence of near-field earthquakes.Therefore,reasonable selection and design of the parameters of the vibration isolation bearings(frequency and damping ratio)will help improve the safety of LNG tanks.For this reason,the vibration differential equations for seismic isolation and anti-seismic storage tanks are established based on the Haroun-housner three-mass theory.The seismic response program for LNG tanks using the Newmark-β algorithm is programmed using Matlab software,and the parameters of the isolation support bearings are studied.The effect of the isolation effect of the tank is as follows: The main research contents and conclusions are as follows:(1)Study the influence of stiffness and damping changes of isolation bearings on the seismic response of small volume and large volume liquid storage tanks under the conditions of three types of sites in the near and far field.Analyze the frequency of the isolation support in the three types of sites near and far field.The response to LNG tanks is greatly affected.A reasonable frequency of seismic isolation bearings can effectively improve the seismic performance of LNG tanks.The damping ratio of the isolation bearing has an influence on the seismic response of the LNG tank,and there is a reasonable range of values for the damping ratio between the isolation frequency and the isolation bearing.The sensitivity of the site to the LNG tank’s seismic response to frequency changes is affected.(2)Study the selection of the reasonable interval between the frequency and the damping ratio of the bottom isolation in the three types of near and far fields.The study found that the reasonable frequency intervals for the lower isolating bearings of the first,second and third types of sites in the near field are[1,6],[1,3]、[5,6],[1,6],Reasonable frequency intervals for the lower isolating bearings in the first,second and third category of the far field are [1,6],[1,4],[1,5].For the large-volume small-diameter ratio tanks,the reasonable isolation frequency ranges for the lower isolating bearings in the first,second,and third class sites in the near field are [2,6],[1,6],[1,5],and far The reasonable isolation frequency ranges for the bottom isolation bearings for the first,second and third class venues are [1,6],[1,2],[1,5].For small-size,high-diameter-ratio cans,the reasonable damping ratios of the lower isolating bearings for the first,second and third types of sites in the near field are [0.1,0.4],[0.2,0.4],and [0.1,0.4],respectively.For the large-size thin tanks,the reasonable damping ratios of the bottom-isolation bearings in the first,second and third categories of the near field are both [0.1,0.4].(3)Study the influence of the site on the seismic response of the base-isolated LNG tank.The isolationeffect ofhigh aspect ratio tanks’ base shear force and bending momentin the near field first class and second class sites is better than that in the far field first class and second class sites,the second type of venue in the near field is more powerful than the second type of venue in the far field in terms of high amplification of the swaying wave.For large-volume,high-diameter-ratio tanks,the second-kind field in the near field has a greater amplification effect on the swaying wave height than the second-field site in the far field,and the isolation rate of the base shear,the base bending moment,and the swaying wave height are in the second class of the near field obviously larger than the second venue in the far field.