# Effect Mechanism of Connection Joints in Fabricated Station Structures
## 4 Numerical Results
### Different Ground Motion Records
#### 4.1.3 Internal Force  
In addition to deformation and plastic strain, the internal force at the joints of the fabricated station structure is also an important index to study seismic performance. Figure 13 shows the maximum internal force distribution at the joint positions of the fabricated station structure.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & \multicolumn{3}{c}{**Impact Rate (\%)**} \\ \cline{5-6}
**Seismic Waves** & **CC** & **QD** & **SZ** & **QD** & **SZ** & **SZ** \\  & & & & **Compared with CC** & **Compared with QD** & **Compared with CC** \\ \hline Parkfield & 7.091 & 6.876 & 6.869 & \(-\)3.03\% & \(-\)0.10\% & \(-\)3.13\% \\ Kobe & 13.24 & 12.84 & 12.92 & \(-\)3.02\% & 0.62\% & \(-\)2.42\% \\ Taft & 14.26 & 14.07 & 14.52 & \(-\)1.33\% & 3.20\% & 1.82\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: Maximum plastic strains (\(\times 10^{-3}\)).  
Figure 12: The time histories of interlayer relative deformations.  
Tables 6-8 show the maximum internal force of the fabricated station structures with the different joint distributions. According to the joint locations of Changchun Metro Station, the maximum internal forces at seven joints were extracted. The maximum internal force and distribution pattern of the CC model, QD model, and SZ model were basically the same. The maximum influence rates of the axial force, shear force, and bending moment were 2.39%, 1.93%, and 6.83%, respectively. The joint distribution position had little influence on the internal force of the fabricated station structure. The internal force difference of the fabricated station structure with different joints was mainly concentrated in the position of the vault and bottom plate, especially the axial force and bending moment. The whole assembly method of the vault and bottom plate was adopted without connection joints. Since the joints undergo coordinated deformation, the internal force of the prefabricated component without joints is greater than or equal to that with joints, which is consistent with the conclusion obtained from the comparative analysis of the internal force of cast-in-place and fabricated station structures in relevant studies [31; 49].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{
\begin{tabular}{c} **Seismic** \\ **Waves** \\ \end{tabular} } & \multirow{3}{*}{**CC**} & \multirow{3}{*}{**QD**} & \multirow{3}{*}{**SZ**} & \multicolumn{3}{c}{**Impact Rate (\%)**} \\ \cline{4-7}  & & & & & **QD** & **SZ** & **SZ** \\  & & & & & **Compared** & **Compared** & **Compared** \\  & & & & **with CC** & **with QD** & **with CC** \\ \hline Parkfield & 13.82 & 13.82 & 13.49 & 0.00\% & \(-\)2.39\% & \(-\)2.39\% \\ Kobe & 15.18 & 15.33 & 15.34 & 0.99\% & 0.07\% & 1.05\% \\ Taft & 14.14 & 14.02 & 13.99 & \(-\)0.85\% & \(-\)0.21\% & \(-\)1.06\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Maximum axial forces (\(\times\)10\({}^{3}\) kN).  
Figure 13: The maximum internal force distributions at the joints.  
According to relevant literature, the change in seismic conditions [50; 51; 52] and peak acceleration [53; 54; 55] of a seismic wave will increase the seismic response of underground structures and, more importantly, will obviously change the seismic response characteristics. In order to further analyze the influence of the joint distribution on the seismic response of the fabricated station structure, the seismic conditions and peak acceleration were analyzed and the results are given in Sections 4.2 and 4.3 according to the research ideas of Section 4.1.