Research On The Parallel Base-Isolation Of Vertical Storage Tanks

The liquid storage tank is the storage equipment of the petroleum and all kinds of liquid chemistry, and it is one of the important components of petrochemical industry installments and the preserving and transporting system facilities. Because most flammable, poisonous and exploded-prone mediums are deposited in this type of container mostly, once the earthquake occurs, the consequence is very serious, and even much worse second disaster, such as fire, pollution, etc. could be caused, which can lead to the severe destruction of our survival environment and huge loss of national economy and production.Base isolation can effectively avoid the damage of the storage tank from the earthquake, protecting the human life and property. Among all the ways of base isolations, the sliding isolation has characteristics with simple, effective isolation, no affecting its vertical load capacity after the isolation layer sliding, lower cost and the difficulties in controlling sliding displacement and so on.The rubber isolation bearing, however, has some features which have enough supple horizontal stiffness, little influence of the vertical load on the horizontal stiffness, better response ability, and higher cost. In this paper, a new parallel isolation system which is composed of the laminated rubber bearings and sliding friction bearings is researched. With reasonable parameter matching, parallel isolation system can effectively bring into play the advantages of the two former ones, reducing the cost and optimizing the effect of isolation. Aimed at the parallel isolation system, the concrete research mainly includes the following parts:Part1: The specific structure of parallel base isolation system is designed reasonably. The base is designed to be a parallel structure system with sliding isolation and isolation supporting by using the ring beam structure. The supporting is made up of the upper and lower plate which is no restriction with ring beam. The plate can adjust central point settlement and the uneven settlement of tanks.Part2: Simplified analysis mechanical model of liquid tank parallel base isolation structure is established.Part3: The simplified analysis motion equations of the parallel base isolation tanks dynamic response are established according to the simplified analysis mechanical model. And the time-history analysis theory and methods which can solve the dynamic response are given out.Part4: The horizontal isolation earthquake response analysis of the tank parallel base isolation structure system is carried out. Aimed at series of floating roof vertical tanks, the isolation effectiveness of the tank parallel base isolation structure system is analyzed comprehensively by adopting time-history analysis method. The impact of various parameters on the earthquake response of the upper storage tank is studied, including different earthquake waves, different site, different seismic intensity, different friction coefficient, different weight ratio of parallel sliding isolation bearing burden the structure total weight, different ratio of height to diameter, different isolation period and the equivalent damping ratio and so on. The results show that, with both weight ratio of parallel sliding isolation bearing burden the structure total weight and the friction coefficient increasing, the isolation effectiveness doesn't work well. However, the types of earthquake waves, the types of sites, seismic intensity, the isolation period and other factors have corresponding effect on the isolation effectiveness and rule.Part5: The base-isolation experiment of the tank parallel base isolation structure system is made. The experiment model is established based on similar principle. Sliding displacement of isolation top layer of the vertical floating tank with isolation, and the lower wall stress of the tank and beginning sliding shear stress are measured through inputting horizontal static thrust force. Then, the test model is analyzed by adopting finite element method. Parallel isolation tank system damping effect is verified.Systematically summarizing the results of research in this paper, research achievements are reached, and the further research in depth content closely relating to the study of this paper is proposed.