## 4 Numerical Simulation Analysis of Large LNG Storage Tank
### Dynamic Response of LNG Storage Tank  
The four seismic waves selected in Section 2.2 were used to analyze the one direction seismic response of the large LNG storage tank. The peak ground acceleration (PGA) of the seismic wave was adjusted to 2.2 m/s. In order to compare the effect of isolation bearings on the seismic response of large LNG storage tanks, numerical models of LNG storage tanks with and without isolation bearings were established, respectively. By comparing the seismic responses of the LNG storage tank, such as acceleration, displacement, base shear force and overturning bending moment, the effect of the isolation bearing was analyzed. The overturning moment is the sum of the bending moment acting on the bottom of each pile foundation. The isolation rate in Table 5 is defined as Equation (4):  
\[\lambda=\frac{R_{non-iso}-R_{iso}}{R_{non-iso}} \tag{4}\]  
where \(R_{non-iso}\) is the seismic response peak value of the seismic storage tank, and \(R_{iso}\) is the seismic response peak value of the isolation storage tank. We then analyzed the base shear and overturning bending moment of large LNG storage tanks. It can be seen from Figures 13 and 14 and Table 5 that after installing the isolation bearing, the base shear force and overturning bending moment of the LNG storage tank are significantly reduced. Under the action of the Wolong wave, the seismic isolation bearing has the best effect, the seismic isolation rate of base shear force is 81.9%, and the seismic isolation rate of overturning bending moment is 64.2%. Under the action of four kinds of seismic waves, the average damping rate of base shear force is 66%, and the overturning moment is 36.0%. This shows that the ability of isolation bearing to reduce the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Elastic Modulus** & **Poisson’s Ratio** & **Density** \\ \hline C40 (outer tank) & 34.5 GPa & 0.167 & 2500 kg/m\({}^{3}\) \\ C50 (pile foundation) & 32.5 GPa & 0.167 & 2500 kg/m\({}^{3}\) \\ Prestressed steel strand & 195 GPa & 0.3 & 7800 kg/m\({}^{3}\) \\ Ordinary reinforced & 200 GPa & 0.3 & 7850 kg/m\({}^{3}\) \\
9\% Ni steel & 206 GPa & 0.3 & 7850 kg/m\({}^{3}\) \\ Expanded perlite & 0.9 GPa & 0.2 & 120 kg/m\({}^{3}\) \\ Foam glass brick & 0.011 GPa & 0.2 & 65 kg/m\({}^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Material parameters of LNG storage tank. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **El Centro** & **Taft** & **Wolong** & **Artificial** \\ \hline \multirow{3}{*}{Base shear force (10\({}^{8}\) N)} & seismic & 1.32 & 2.05 & 1.71 & 1.73 \\  & isolation & 0.61 & 0.77 & 0.31 & 0.55 \\  & isolation rate & 53.8\% & 62.4\% & 81.9\% & 68.2\% \\ \hline \multirow{3}{*}{Overturning bending moment (10\({}^{8}\) N-m)} & seismic & 2.18 & 3.37 & 2.82 & 2.84 \\  & isolation & 1.92 & 2.46 & 1.01 & 1.68 \\  & isolation rate & 11.9\% & 27.0\% & 64.2\% & 40.8\% \\ \hline \multirow{3}{*}{Acceleration of the outer tank wall (m/s\({}^{2}\))} & seismic & 4.92 & 5.34 & 5.35 & 4.04 \\  & isolation & 2.47 & 2.36 & 2.88 & 2.55 \\  & isolation rate & 49.8\% & 55.8\% & 46.0\% & 36.9\% \\ \hline \multirow{3}{*}{Displacement of the outer tank wall (m)} & seismic & 0.0054 & 0.0065 & 0.0059 & 0.0057 \\  & isolation & 0.0380 & 0.0322 & 0.0494 & 0.0174 \\  & isolation rate & \(-\)604\% & \(-\)395\% & \(-\)737\% & \(-\)205\% \\ \hline \multirow{3}{*}{Effective dynamic stress of outer tank wall (MPa)} & seismic & 0.86 & 1.01 & 1.09 & 0.85 \\  & isolation & 0.16 & 0.14 & 0.21 & 0.09 \\ \cline{1-1}  & isolation rate & 81.4\% & 86.1\% & 80.7\% & 89.4\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Peak seismic response of 200,000 cubic meters of the LNG storage tank. base shear force is significantly better than the ability to reduce the overturning bending moment. We then analyzed the seismic response of the outer wall of an LNG storage tank. The displacement and acceleration diagrams of the seismic storage tank and the seismic isolation storage tank are compared, as shown in Figures 15 and 16.