## 4 Experimental Research
### Experimental Process
#### 4.2.1 Stages for the Pre-Stress Deviation Adjustment  
1. In this experiment, the length of DC1 was corrected by tightening or loosening the screw, and one end of the screw was connected to cable and the other end was connected to the supporting beam by a screw cap, as shown in Figure 4. In order to accurately obtain the adjustment length of the adjustment cable, it was necessary to begin with the measurement of the variation value of the cable length. \(\Delta d=2\) mm when the screw cap of each cable rotated a circle. The rotation angle was calculated according to the length adjustment value of each adjustment cable.
2. According to the adjustment value of each DC1 in the sequence of number 2-10-18-26-34-42-50-58-66-74-82-90, the length of each DC1 was corrected accordingly, and the  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Leading** & **Weight** & **1-DC1** & **2-DC1** & **3-DC1** & **4-DC1** & **5-DC1** & **6-DC1** & **7-DC1** & **8-DC1** & **9-DC1** & **10-DC1** & **11-DC1** & **12-DC1** \\ \hline
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
1 & 20 & 3 & 4 & 4 & 3 & 4 & 3 & 4 & 3 & 4 & 3 & 3 & 3 \\
2 & 40 & 6 & 6 & 7 & 6 & 7 & 6 & 7 & 6 & 6 & 7 & 7 \\
3 & 60 & 10 & 9 & 10 & 10 & 10 & 10 & 10 & 9 & 10 & 10 & 11 & 10 \\
4 & 80 & 14 & 12 & 14 & 14 & 13 & 13 & 14 & 13 & 13 & 14 & 14 & 14 \\
5 & 100 & 17 & 15 & 17 & 16 & 17 & 16 & 17 & 17 & 17 & 16 & 17 & 17 \\
6 & 120 & 20 & 18 & 20 & 20 & 20 & 19 & 21 & 20 & 20 & 20 & 21 & 21 \\ \hline \multicolumn{12}{c}{\(k\)} & 58.23 & 65.0 & 57.68 & 59.17 & 58.44 & 61.26 & 56.59 & 59.56 & 58.80 & 59.17 & 56.23 & 56.77 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The coefficients k of 12 DC1.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Element No.** & **2** & **10** & **18** & **26** & **34** & **42** & **50** & **58** & **66** & **74** & **82** & **90** \\ \hline Theoretical value (k,N) & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 \\ \hline Measured value (k,N) & 1.63 & 1.99 & 1.90 & 1.57 & 1.86 & 1.94 & 1.52 & 1.58 & 1.90 & 1.53 & 2.06 & 1.95 \\ \hline Deviation (\%) & \(-6.86\) & 14.00 & 8.63 & \(-10.17\) & 6.29 & 10.80 & \(-13.37\) & \(-9.43\) & 8.80 & \(-12.46\) & 17.83 & 11.31 \\ \hline \(\delta\varepsilon_{0}^{\mathrm{t}}\) (m) & \(-0.0030\) & 0.0188 & 0.0103 & \(-0.0140\) & 0.0055 & 0.0079 & \(-0.0281\) & \(-0.0263\) & \(-0.0023\) & \(-0.0142\) & 0.0257 & 0.0202 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The pre-stress deviations of measuring points and adjustment values of cable length.  
forces of the 12 DC1 were recorded and compared with the theoretical values after the completion of adjustment of each stage. For convenience, this paper only recorded the values of internal forces of each measuring point at the completion of the four stages; namely, the lengths of cables 2, 10, and 18 were adjusted in the first stage, the lengths of cables 26, 34, and 42 were further adjusted in the second stage based on the first stage, the lengths of cables 50, 58, and 66 were further adjusted in the third stage based on the second stage, and the lengths of cables 74, 82, and 90 were adjusted in the final stage based on the third stage.