Dynamic Response Analysis Of Three Dimensional Isolation Of Large Scale Storage Tank Under The Action Of Near Field Earthquake

Vertical storage tank is an important liquid storage container in petrochemical industry,and it belongs to the lifeline engineering of energy supply.It often stores flammable,explosive and toxic mediums,once destroyed in the earthquake,it will often be accompanied by serious secondary disasters such as fire and explosion which has a great impact.The base isolation can effectively protect the storage tank from earthquake damage and ensure the safety of the people’s life and property.At present,most of the isolation bearings used in storage tanks are horizontal seismic isolation systems,which can not reduce the seismic response under the vertical earthquake excitation.The actual earthquake motion is a multidimensional random vibration,including three translational and three rotational components.While reducing its horizontal dynamic response,vertical earthquake may become an important cause of tank failure.The research of tank isolation is mostly based on far-field seismic excitations.For the structures with long natural vibration periods,the adverse effects of long period velocity components on near-field earthquakes can not be ignored.This article considers the near-field horizontal and vertical seismic actions,the 15×10~4m~3 large vertical storage tank is taken as the research object,and the three-dimensional isolation system is introduced into the tank isolation.The contents of the study are as follows:(1)The finite element model of three-dimensional isolation tank with fluid solid coupling is established by using the large general finite element software ADINA.By means of time history analysis,the dynamic response of the near and far field under horizontal and vertical seismic action is analyzed and compared,and the influence of the near field pulse earthquake on the dynamic response of the isolated tank is emphatically analyzed.The results of the study show that:for a 15×10~4m~3 storage tank,the influence of multidimensional earthquake should be considered;the three-dimensional isolation system can significantly reduce the dynamic response of horizontal and vertical seismic excitations but the sloshing wave height can not be controlled,and the isolation effect of far-field seismic excitations is better than near-field seismic excitations;under the near field horizontal seismic excitation,the sloshing wave of liquid storage is far higher than far-field seismic excitation;The sloshing wave height under vertical seismic excitation is small,so it can be ignored in actual engineering.(2)By changing the spring element parameters,the influence of horizontal and vertical isolation parameters on the dynamic response of tanks is analyzed.The results show that:the longer the horizontal and vertical isolation period is,the smaller the effective dynamic stress of the tank wall is;under the far field earthquake excitation,it is suitable for the horizontal isolation period to take the 2~4s damping ratio 0.1~0.4;for the near field earthquake excitation,the appropriate damping ratio is between the 0.1~0.4 the horizontal isolation period is between the 3~4s;under the vertical excitation of the near field and far field,the vertical isolation period is between 1~2s and damping ratio is between 0.1~0.4,which has good isolation effect;changing the parameters of isolation layer has little effect on the wave height of horizontal seismic excitation.(3)Shaking table tests were conducted on the isolation tanks.The acceleration and displacement responses of the tanks at the near or far field and horizontal or three-way excitation were compared.The finite element results were compared with some experimental results.Research indicates:apart from a few test points the peak responses of acceleration and displacement under the excitation of three-dimensional seismic data are larger than those under horizontal excitation,and the amplification effect of multi-dimensional ground motion on the seismic response of the storage tank needs to be considered;with horizontal near far field seismic excitation,HDR damping effect is significant,and the acceleration response of the tank wall is greatly reduced;under three earthquake excitation,the storage tank still has a great peak acceleration after isolation,and the horizontal acceleration caused by the vertical ground motion is significant,It shows that the HDR does not have the function of vertical isolation.;compared with the finite element solution,the shaking table test is consistent with the trend of the finite element solution,the peak difference is small,they are mutually verified.