International Core Journal of Engineering 2020-26 | Page 55

foundation soil to simulate the interaction of the two.
angle weld is different from the strength of the tank wall.
When the maximum Mises stress exceeds the strength of the
large angle weld, it will cause the damage of the weld.
Because the large angle weld is located at the connection
between the wall plate and the floor of the tank, once the
damage occurs, the light affects the normal operation of the
tank, and the weight leads to the leakage accident. So the
large angle weld should be the key research area of the
safety protection of the storage tank.
In addition to the above differences, the load and
boundary conditions of the three models are the same. The
loads applied to the tank include: the weight of the tank and
its accessories, the hydrostatic pressure of the tank bottom
plate, and the hydrostatic gradient of the tank wall. The
settlement of the foundation is simulated by the vertical
displacement on the lower side of the soil. The settlement of
the foundation is the combined harmonics described in the
upper section. The settlement of the center point of the
foundation takes the average value of the settlement of the
base of the tank, and the settlement of the other points is
linearly along the radius direction of the foundation [8-9] . The
vertical displacement of the foundation soil is simulated,
and the radial displacement and tangential displacement are
restrained. The rest of the model are free boundaries.
Since there is no difference in appearance between the
three models, only one graph is used to display the finite
element model of the storage tank, as shown in Figure 1.
(a)


Fig.1 Finite element model of tank
IV. C OMPARISON AND A NALYSIS OF T ANK S TRUCTURE
R ESPONSE M ODELS
(b)

Three kinds of finite element models are used to
calculate respectively, and the results are compared,
analyzed and summarized.
Due to the different methods used in modeling, there are
some differences in the numerical results of the three
models, but all show some of the same rules. After the
settlement of the storage tank, the maximum Mises stress
calculated by the three models appears at the large-angle
weld joint between the wall plate and the floor plate, and
their positions are the same. The calculated maximum radial
displacement of the tank also appears in the same position in
the tank roof. The maximum vertical compressive stress of
the tank body also shows a similar pattern, and the
calculated maximum vertical compressive stress appears at
the same position on the bottom of the tank wall. In order to
more intuitively demonstrate the similarity of the results of
the three model calculations, radial displacement is selected
to display the cloud diagram, as shown in Figure 2.
(c)

Fig.2 Radial displacement of three models
After the settlement of the tank foundation, the tank has
different degrees of deformation, and the part of the tank
wall is obviously convex or concave, and the maximum
radial displacement appears in the area of the top of the tank.
For the external floating roof tank, the deformation of the
tank wall will affect the upward and downward movement
of the floating disc. If the part of the tank wall is more
deformed than the allowable value of the normal work of the
floating plate, the tray phenomenon will appear and the tank
cannot work properly. In addition, regardless of the type of
storage tank, excessive deformation of the tank wall may
cause tearing of the tank wall and lead to leakage accidents.
Therefore, it is necessary to monitor the radial displacement
of the tank wall, especially the radial displacement of the
upper wall panel of the storage tank, so as to prevent
excessive deformation of the tank wall.
In addition, the distribution of radial displacement along
the tank height in the vertical direction of the maximum
radial displacement is investigated. It is found that the
calculated results of the three models show a similar
distribution law, as shown in Figure 3. With the increase of
the tank height, the radial displacement of the tank is
generally increasing, and the maximum value is obtained at
the top of the tank, while the radial displacement decreases
in the height of the anti wind ring and the reinforcement ring.
The common law reflected by the three models can
provide valuable reference for the safety protection of
storage tanks. The maximum Mises stress appears at the
large angle weld of the tank, while the strength of the large
In addition, the maximum vertical pressure stress of the
tank appears at the bottom of the tank wall. When the
vertical pressure stress increases, the structure of the bottom
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