# Seismic Analysis of a Large LNG Tank Considering Different Site Conditions
## 4 Seismic Analysis of a Large Liquefied Natural Gas (LNG) Tank  
### Project Overview  
This study employs a 160,000 m\({}^{3}\) LNG prestressed storage tank reproduced from an existing and widely-applied design as shown in Figure 4[15]. The outer tank has an inner diameter of 82 m, a wall height of 38.55 m, a wall thickness of 0.8 m, and a dome thickness of 0.4 m. Additional components are embedded within the tank to keep the moisture-proof linings and roof-bearing rings in place.  
Figure 3: SPH-FEM simulation results of liquid sloshing with different element sizes at time 2.0 s; (a) 3 mm, (b) 5 mm, (c) 7.5 mm, (d) 10 mm.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Depth of Liquid (mm)** & **Housner’s Result** & **Experimental Result** & **SPH-FEM Result** \\ \hline
50 & 1.23 & 1.28 & 1.22 \\
100 & 1.54 & 1.52 & 1.56 \\
150 & 1.64 & 1.63 & 1.67 \\
200 & 1.68 & 1.67 & 1.72 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Sloshing frequency results from SPH-FEM method compared to theoretical and experimental results.  
The inner tank has a total of 10 layers each with a height of 3.55 m; as shown in the diagram, layer R1/24.9 refers to the first layer from the bottom with a thickness of 24.9 mm. Additional thinner layers rest on top the first layer as given in Table 4.  
The LNG storage tank consists of four components including the LNG, an inner tank composed of 9% Ni steel, an insulation layer, and an outer tank. The tank is characterized by excellent low-temperature resistance [30,31], good weldability, and low susceptibility to cold cracks. The insulation layer consists of expanded perlite and resilient felt. The expanded perlite is attached to the inner wall of the outer tank, and the outer wall of the inner tank is lined with resilient felt that provides elastic properties for the perlite and prevents it from settling. This elasticity is essential due to temperature-induced tank shrinkage. The prestressed concrete external tank increases structural safety during LNG leakage. The material of the outer tank is chosen to be 60 MPa high-strength concrete according to the advice of [PERSON] [32]. The respective material properties of the tank and the LNG are listed in Tables 5 and 6.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{**Density (kg/m\({}^{3}\))**} & \multirow{2}{*}{**Sonic Speed (m/s)**} & \multirow{2}{*}{**Dynamic Viscosity (kg/(m\(\cdot\)s))**} & \multicolumn{2}{c}{**Coefficients of the Equation of State**} \\ \cline{5-6}  & & & & \(s\) & \(\Gamma_{0}\) \\ \hline LNG (liquid) & 480 & 1500 & 0.00113 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Material properties of LNG.  
Figure 4: LNG storage tank cross section (unit: mm) [15].  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Layer**} & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** \\ \hline Thickness (mm) & 24.9 & 22.4 & 19.8 & 17.3 & 14.7 & 12.2 & 12 & 12 & 12 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Thickness of each layer of the inner tank.