| Vertical cylindrical storage tank is widely used for oil and petrochemical industry and related enterprises to store flammable and explosive, toxic matter. Because of the internal fluid sloshing is too large often causes tank damage under seismic excitations and easy to cause secondary disasters such as fire, leakage. So this will cause serious influence to the survival of mankind and the ecological environment and serious losses to the national economy. On the other hand in the design of vertical cylindrical storage tank, the sloshing wave height as an important index for the design of storage tank, this aspect has already specified in the multinational codes. "Code for design of vertical cylindrical welded steel oil tanks" (GB50341-2014)[5] requirements:the distance of the design of fixed and floating roof tank from the highest liquid level to the highest tank wall should be greater than the liquid sloshing wave height. Sloshing wave height plays an important indicator for tank height design and violent liquid sloshing may cause tank wall occur elephant-foot buckling and diamond-shaped buckling etc. So, if can reduce liquid wave height effectively, it will bring good results for the optimization design and safety design of tank.For the purpose of suppressing liquid sloshing, this paper substitutes PMMA for steel to establish 1:30 reduced-scale model, setting relative width and location of ring baffles as the parameters to be optimized and utilizing wave height amplitude, tank wall acceleration and pressure as measures to evaluate the effectiveness of baffled and un-baffled model experiment subjected to different seismic excitations. Experimental results show that the ring baffle haves some inhibitory effect to the fluid sloshing wave height, but the inhibitory effect greatly influenced by the relative width and the relative position. Model for this experiment, when the relative width at 0.125～0.175 and the relative location at 0.125～0.225, the effect of suppressing wave is the most remarkable and also effective to the acceleration amplitude of tank bottom. Although the tank wall pressure amplitude is magnified but still far less than the code limit. Secondly according to the results found that ring baffle is more effective for the short period of Northridge wave, peak acceleration and the peak compressive stress got better control, but for the long period of El Centro wave and Taft wave control effect is relatively poor. The most important thing is sloshing wave height gets significantly reduced, which makes the liquid height limit has been "liberated". Compared with un-baffled tanks, baffled tank liquid height can be designed to be more highly, which has vital significance to add tanks reserves and increase the utilization ratio of covering area.With the aid of the finite element software ADINA, numerical simulation is carried out to establish the finite element model of un-baffled and baffled storage tank. Numerical simulation results show that when the relative location at 0.125～0.225 andthe relative width near 0.15, the effect of suppressing wave is the most remarkable, additionally near the bottom of the tank, stress reached the maximum peak, which is consistent with elephant-foot buckling area, so it has guiding significance to prevent such failure. By comparing the numerical simulation data and test results verify the correctness and reliability of the finite element model so that it can be used to study the complex parameters of storage tank. According to the results of simulation on ring baffle influence to do theory analysis for the storage tank’s sloshing height and then put forward the calculation formula of storage tank fluid sloshing wave height attenuation rate which is considering the effects of ring baffle. Another wave height attenuation rate are obtained by data fitting which is opposed to baffles’ relative width and the relative position is strong nonlinear relation. By comparing the results of the formula and test values, the correctness of the calculation method is verified. |
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