# Development of a Pre-Evaluation and Health Monitoring System for FAST Cable-Net Structure
## 3 Establishment of the FAST MST Model
### Update Process of MST Model  
The update procedure of MST model data will be described below. The stroke change of the actuators first needs to be updated into the model. The ambient temperature is used as the load condition for model calculation. The deformation of pull-down cables is equivalent to the strokes of connected actuators, which is converted into the temperature change of the pull-down cables and superimposed with the ambient temperature through Equation (1):  
\[\Delta T_{i}=\frac{\Delta L_{i}}{\alpha\times L_{i}}+T_{\text{e}} \tag{1}\]  
Here, \(\Delta T_{i}\) represents the final temperature change of the \(i\)th pull-down cable. \(\Delta L_{i}\) is the deformation of the \(i\)th pull-down cable. \(\alpha\) indicates the linear temperature expansion coefficient of the cable, which is \(1.2\times 10^{-5}\). \(L_{i}\) is the length of the \(i\)th pull-down cable in the model. \(T_{e}\) stands for ambient temperature. Ineffective actuators, based on different kinds of failure-response modes, can be divided into two situations: pulled out or stuck. The connected pull-down cable in the MST model would be disabled if the actuator was pulled out; when actuator is found stuck, the last stroke collected from the cycle is entered into the model. Since FAST was completed and put into use, we have continued to measure the regularly measured data every six months, which include: (1) the coordinates of all lug-plate pinholes, which are used to simulate the relative displacement between the edge main cable and the joints of the beam; (2) the coordinates of cross nodes between the main cables and pull-down cables under the basic spherical surface in a curvature radius of 300 m and the strokes of the actuators. These coordinates are used to check whether the cable net has  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**Cable Body**} & \multicolumn{3}{c}{**Double Cable**} & \multicolumn{3}{c}{**Connection Node**} \\ \cline{3-10}
**Serial** & **Specification** & \multicolumn{1}{c}{ \begin{tabular}{c} **Cross-** \\ **Sectional** \\ **Area** \\ \end{tabular}  } & \begin{tabular}{c} **Linear** \\ **Weight** \\ \end{tabular}  & \begin{tabular}{c} **Outer** \\ **Diameter** \\ \end{tabular}  & \begin{tabular}{c} **Limit Cable** \\ **Force** \\ \end{tabular}  & **Weight** & **Length** & **Weight** & \begin{tabular}{c} **Outsourcing** \\ **Diameter of** \\ **Pinhole Centre** \\ \end{tabular}  \\ \cline{3-10}  & & \multicolumn{1}{c}{ \begin{tabular}{c} **cm\({}^{2}\)** \\ \end{tabular}  } & \begin{tabular}{c} **kg/m** \\ \end{tabular}  & \begin{tabular}{c} **mm** \\ \end{tabular}  & \begin{tabular}{c} **km** \\ \end{tabular}  & \ \begin{tabular}{c} **kg** \\ \end{tabular}  & \begin{tabular}{c} **mm** \\ \end{tabular}  \\ \hline
1 & \begin{tabular}{c} OVMST15-1 \\ \end{tabular}  & 1.4 & 1.37 & 23 & 260 & 10.5 & 390 & — & — \\ \hline
2 & \begin{tabular}{c} OVMST15-2 \\ \end{tabular}  & 2.8 & 3.29 & 44 & 520 & 40 & 640 & 41 & 270 \\ \hline
3 & \begin{tabular}{c} OVMST15-2J3 \\ \end{tabular}  & 3.4 & 3.65 & 44 & 629.5 & 40 & 640 & 41 & 270 \\ \hline
4 & \begin{tabular}{c} OVMST15-3 \\ \end{tabular}  & 4.2 & 4.52 & 47 & 782 & 52 & 700 & 55 & 290 \\ \hline
5 & \begin{tabular}{c} OVMST15-3J3 \\ \end{tabular}  & 4.8 & 4.87 & 47 & 891.5 & 52 & 700 & 55 & 290 \\ \hline
6 & \begin{tabular}{c} OVMST15-4 \\ \end{tabular}  & 5.6 & 5.71 & 51 & 1040 & 70 & 800 & 90 & 360 \\ \hline
7 & \begin{tabular}{c} OVMST15-4J3 \\ \end{tabular}  & 6.2 & 6.07 & 51 & 1149.5 & 70 & 800 & 90 & 360 \\ \hline
8 & \begin{tabular}{c} OVMST15-5 \\ \end{tabular}  & 7 & 7  
an overall displacement. (3) The strokes and coordinates of all actuators can be checked to determine whether the positions of pull-down cables move or their lengths change. The similarity between the regularly measured data and the real-time collected data is that they are all stored in Excel files, while the difference is that the regularly measured data are used to modify the geometry of the ANSYS model by invoking the APDL program.