## 4 Experimental Research
### Experimental Process
#### 4.2.2 Result Analysis of Pre-Stress Deviation Adjustment  
After the completion of adjustment of each stage, the theoretical values and measured values of internal forces of measuring points and their deviations were shown in Table 3.  
1. The adjusted pre-stress deviation of each measuring point can be effectively corrected, suggesting the feasibility of error adjustment theory and its practical application to guide the adjustment of pre-stress deviation within the actual pretention structure construction.
2. In the adjustment process, although the deviations of some measuring points increased at certain stages, the pre-stress deviations of all measuring points gradually approached the ideal values until they were finally achieved.
3. Pre-stress deviations of measuring points for the 12 DC1 were not only caused by the length deviations of the 12 DC1, but also derived from the length errors of other elements, node errors, as well as adjustment errors which occurred during the process of the length adjustments of the 12 DC1. Thus, it was difficult to absolutely eliminate the pretention deviations, and there was still the presence of a few pre-stress deviations in the experiment.  
Figure 4: Screws connecting to cables and beam.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Adjustment Order** & **Measuring Point** & **2** & **10** & **18** & **26** & **34** & **42** & **50** & **58** & **66** & **74** & **82** & **90** \\ \hline \multirow{3}{*}{The first-stage adjustment (2 + 34 + 42)} & Theoretical value & \(-1.01\) & \(-0.72\) & \(-0.81\) & \(-1.13\) & \(-0.84\) & \(-0.76\) & \(-1.18\) & \(-1.12\) & \(-0.86\) & \(-0.92\) & \(-0.92\) & \(-0.89\) \\  & Measured value & \(-1.05\) & \(-0.70\) & \(-0.82\) & \(-1.20\) & \(-0.78\) & \(-0.76\) & \(-1.20\) & \(-1.18\) & \(-0.81\) & \(-0.90\) & \(-0.90\) & \(-0.94\) \\  & Deviation \% & 3.96 & \(-2.78\) & 1.23 & 6.19 & \(-7.14\) & 0.00 & 1.69 & 5.36 & \(-5.81\) & \(-2.17\) & \(-2.17\) & \(5.62\) \\ \hline \multirow{3}{*}{The second-stage adjustment (2 + 34 + 42)} & Theoretical value & 3.82 & 4.11 & 4.03 & 3.71 & 4.01 & 3.99 & 3.89 & 3.92 & 3.92 & 3.92 & 3.94 \\  & Measured value & 4.02 & 3.93 & 4.08 & 3.90 & 3.84 & 4.03 & 4.12 & 3.71 & 3.79 & 3.96 & 4.13 \\  & Deviation \% & 5.24 & \(-4.38\) & 1.24 & 5.12 & \(-4.24\) & 1.00 & 3.60 & 5.10 & \(-5.36\) & \(-3.32\) & 1.02 & 4.82 \\ \hline \multirow{3}{*}{The third-stage adjustment (50 + 58 + 66)} & Theoretical value & 3.88 & 4.17 & 4.03 & 3.94 & 3.98 & 3.98 & 3.97 & 3.97 & 3.97 & 3.97 & 3.98 & 3.99 \\  & Measured value & 4.10 & 4.00 & 4.11 & 4.12 & 3.75 & 4.03 & 4.14 & 4.20 & 3.70 & 3.85 & 3.94 & 4.20 \\ \cline{1-1}  & Deviation \% & 5.67 & \(-4.08\) & 1.99 & 4.57 & \(-5.78\) & 1.26 & 4.28 & 5.79 & \(-6.80\) & \(-3.02\) & \(-1.01\) & 5.26 \\ \hline \multirow{3}{*}{The fourth-stage adjustment (74 + 82 + 90)} & Theoretical value & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 & 1.75 \\ \cline{1-1}  & Measured value & 1.83 & 1.68 & 1.78 & 1.82 & 1.66 & 1.77 & 1.81 & 1.79 & 1.69 & 1.70 & 1.77 & 1.82 \\ \cline{1-1}  & Deviation \% & 4.57 & \(-4.00\) & 1.71 & 4.00 & \(-5.14\) & 1.14 & 3.43 & 2.29 & \(-3.43\) & \(-2.86\) & 1.14 & 4.00 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Adjustment to pre-stress deviation of the measuring point in four stages (kN).