Research On Seismic Response Of Vertical Storage Tank

Vertical liquid-storage tank are important facilities in oil storage and transportation. Recently, with the rapid development of petroleum chemistry industry, more and more liquid-storage tanks have been built. China locates in an area with high-frequency of earthquakes. Furthermore, most of liquid-storage tanks were built in the seismic area. Therefore, it is important to research the seismic response of the liquid-storage tanks.At present, the tank's developments are thin wall, base floating and large volume. Liquid-storage tanks with floating-roof are primary equipments for oil storage, and the tank bodies are placed on bases freely. The research of tank's seismic response is focus on unanchored tanks which have the widest application. The seismic response analysis of liquid-storage tanks is usually based on simplified theoretical model. Some numerical analyses have been made, but has not been applied in engineering practice widely for its using limitation and calculating accuracy. In this thesis, the professional finite element software ANSYS has been applied in static and seismic response analysis of liquid-storage tanks. The main research and achievement are given as follows:Part1: On the base of the summary of elastic-plastic theory, the finite element knowledge and the analysis of different elastic-plastic constitutive models, the elastic-plastic constitutive relations which is fit for soil-tank system is confirmed.Part2: The finite element model of liquid storage tank with soil structure considering nonlinear contact is built, and the time acceleration method is chosen by the characteristics of different seismic wave inputting methods.Part3: The modal analysis is proceeded for the 2000m3 and 50000 m3 tanks,and the former three-level mode is calculated respectively. At the same time, the influence analysis of parameters is processed which include floating-roof, the tank wall style and the strengthen girder.Part4: The analysis of dynamic response of 2000m3 tank and 50000m3 tank under the horizontal earthquake is given out. The analysis includes the height of sloshing wave, the stress and the displacement of the tank wall, the uplifting of the base plate, the base moment and base shearing force. The cause and destroying mechanism of the Elephant Foot of tank are analyzed primarily. At the same time the seismic response of anchored tanks are analyzed, and the results are compared with unanchored tanks.