## 4 Test Results and Analysis
### Test Results and Analysis of Horizontal Initial Displacement
#### 4.2.2 Floor Acceleration Response  
When the supporting ejector explodes, the structure attenuates vibration. Vibration signals are gathered using sensors situated on each floor, and dynamic signals are input into data gathering software to obtain acceleration attenuation curves for each floor, as well as spectrum characteristics. Since the acceleration attenuation fluctuates smoothly over three seconds and is nearly straight over four seconds, the acquisition time is set at six seconds, which accurately reflects the degree of attenuation. In the direction of travel, Figure 20 illustrates the free acceleration attenuation curves and the related frequency spectra for the first floor and the roof floor (Y direction).  
To compare with the seismic structure and emphasize the isolation structure's damping effect, the measured acceleration of the isolation structure's first floor (154 gal) is input into the seismic structure's first floor model for calculation. Thus, the acceleration response of each floor is determined and then compared to the acceleration response of the isolated structure to determine the floor's associated seismic-reduction rate. The findings are summarized in Table 5. The seismic-reduction rate in Table 5 is equal to the following: (seismic model value--measured value of isolated structure)/seismic model value.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Mode Order**} & \multicolumn{2}{c}{**Natural Vibration Period/s**} & \multicolumn{2}{c}{**Damping Ratio/\%**} \\ \cline{2-5}  & **Seismic Structure** & **Horizontal Movement** & **Seismic Structure** & **Horizontal Movement** \\ \hline First order & 0.416 & 1.173 & 5.00 & 22.39 \\ Second order & 0.221 & 0.386 & 5.00 & 10.86 \\ Third order & 0.115 & 0.176 & 5.00 & 3.72 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of analysis results of first three-order self-vibration characteristics of structure.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Floor** & **Seismic Structure/gal** & **Isolation Structure/gal** & **Seismic-Reduction Rate/\%** \\ \hline Roof floor & 351 & 195 & 45.80 \\
3 & 254 & 173 & 31.89 \\
2 & 207 & 169 & 18.36 \\
1 & 154 & 154 & / \\ \hline \hline \end{tabular}
\end{table}
Table 5: Structural acceleration and seismic-reduction rate.  
As illustrated in Table 5, the acceleration of the seismic structure increases with the rise of the floors, and the acceleration of the top floor is 2.28 times that of the bottom floor, which is consistent with the seismic structure law. However, the acceleration of the isolation structure increases slightly as the floor increases and generally exhibits horizontal movement characteristics, indicating that the seismic resiliency of the structure is intact, but the roof floor has a certain amplification effect, and its amplification factor is 1.27 (195 gal/154 gal).  
It should be noted that the calculated seismic-reduction rate is low due to the fact that the force delivered during the test is located on the structure's first floor, above the isolation layer. In comparison to the seismic wave input from the underground and transmitted to the superstructure via the isolation layer's attenuation, the floor acceleration is not attenuated by the isolation layer, and the isolation structure's response is large, but the isolation structure has good shock absorption effect (which can still be seen from the test data).