## 3 Analysis of Torque Load Transfer Mechanism  
### Standard Scale Model  
In this test, the strain gauge on the sidewall of the foundation ring is located on the outer side, so the measured torsional strain (stress) should be the maximum. Through the above analysis, the theoretical shear stress in each specimen under torsional load can be calculated. Based on the mean value of shear stress on different cross-sections, the transfer mechanism of the torsional load can be further analyzed.  
Here, the standard specimen ZT-1 is taken as an example. To avoid the influence of stress concentration at the opening of the foundation ring, the corresponding stress measurement point was arranged at a certain distance from the opening. The stress at each measurement point on the flat cross-section above or under the opening was analyzed, as shown in Figure 8.  
Consider that when the experimental model was being made, the isolation measures of the template paint and lubricant had been applied to the sidewall of the foundation ring. Assume that the adhesion between the foundation ring sidewall and the concrete is small at this time. The calculation method for the torque load on the three sections is as follows:  
1. Actual torque load applied  
The actual torque load was applied step by step, according to Table 4. The actual applied tension value was measured by two tension sensors, and then the actual applied torque load was calculated according to Equation (10).  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Level** & **Security Level** & **Vertical Load** & **Theoretical Torque Value (kN-m)** & **One-Way Tension Value (kN)** \\ \hline
0 & 0 \(T\) & 216.78 & 0 & 0 \\
1 & 0.2 \(T\) & 216.78 & 3.41 & 1.07 \\
2 & 0.4 \(T\) & 216.78 & 6.82 & 2.13 \\
3 & 0.6 \(T\) & 216.78 & 10.22 & 3.20 \\
4 & 0.8 \(T\) & 216.78 & 13.63 & 4.26 \\
5 & 1 \(T\) & 216.78 & 17.04 & 5.33 \\
6 & 1.2 \(T\) & 216.78 & 20.45 & 6.39 \\
7 & 1.35 \(T\) & 216.78 & 23.00 & 7.46 \\
8 & 1.5 \(T\) & 216.78 & 25.56 & 8.52 \\ \hline \end{tabular}
\end{table}
Table 4: Loading levels of torque T.  
Figure 7: Arrangement schemes for strain measurement points on the foundation ring. (a) Elevation view of strain gauge layout (b) Top view of strain gauge layout.  
2. Torque load transferred to the foundation ring On the outer surface of the foundation ring, at a certain distance upwards from the top radial reinforcement, a 45\({}^{\circ}\) right-angle strain rosette measurement point on the top of the first layer was set, and the measured strain value can be calculated according to Equation (8).
3. Actual torque load on the bottom flange of the foundation ring On the outer surface of the foundation ring, at a certain distance downwards from the top radial reinforcement, a 45\({}^{\circ}\) right-angle strain rosette measurement point at the bottom of the first layer was set, and the torque load of this section can also be calculated.  
At this time, it can be considered that the torque load difference between \(T_{\text{up}}\) and \(T_{\text{bottom}}\) is shared by the top radial reinforcement. Using this simplified analysis method, the forces of top radial reinforcement and the foundation ring of ZT-1 during the whole loading process can be summarized, as shown in Figure 9.  
Figure 8: Torsional shear stress in the foundation ring of ZT-1.  
Figure 9: Torque load sharing ratios of ZT-1.  
Under the torque load, the foundation ring shares the main torque load except at the first stage. Under 0.4-1.0 \(T\), the foundation ring shares about 90%; after 1.0 \(T\), the ratio changes to about 85%. After the torque load is transferred through the top radial reinforcement to the foundation ring, it is further transferred to its lower part. As a result, the top radial reinforcement on the top layer shares only a small part.