## 4 Results of Content Analysis
### Methods Integrated with ANN Applied in CM Research  
The result shows that 61% of studies established a hybrid model in which ANN is integrated with other methods to solve the problems in CM, and the number is considerably greater than that of the individual model. Researchers are adopting more and more \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Code** & **Application Fields** &
\begin{tabular}{l} **Freq\({}^{J}\)** \\ **Percentage** \\ \end{tabular} & **Specific Topics** & **Freq.** & **Percentage** \\ \hline \multirow{4}{*}{1} & \multirow{4}{*}{Cost} & & Project cost estimation & 13 & 11.61\% \\  & & & Materials prices prediction & 5 & 4.46\% \\  & & 26 & Bid price prediction & 3 & 2.68\% \\  & & 23.21\% & Forecasting construction cost index & 2 & 1.79\% \\  & & & Usage and service cost estimation & 2 & 1.79\% \\  & & & Maintenance cost of equipment prediction & 1 & 0.89\% \\ \hline \multirow{2}{*}{2} & \multirow{2}{*}{Performance} & 18 & Corporate performance evaluation & 5 & 4.46\% \\  & & 16.07\% & Project performance evaluation & 11 & 9.82\% \\  & & & Industry performance evaluation & 2 & 1.79\% \\ \hline \multirow{3}{*}{3} & \multirow{3}{*}{Safety} & 13 & Worker safety behavior assessment & 10 & 8.93\% \\  & & 11.61\% & Accident analysis for construction safety & 2 & 1.79\% \\  & & 11.61\% & Safety climate prediction & 1 & 0.89\% \\ \hline \multirow{2}{*}{4} & \multirow{2}{*}{Quality} & 9 & Health monitoring of construction structure & 6 & 5.36\% \\  & & 8.04\% & Construction stability testing & 3 & 2.68\% \\ \hline \multirow{2}{*}{5} & \multirow{4}{*}{Resource} & & Mechanical equipment management & 3 & 2.68\% \\  & & Material management & 2 & 1.79\% \\  & & 9 & Fund management & 2 & 1.79\% \\  & & 8.04\% & Patent technology management & 1 & 0.89\% \\  & & & Human resources management & 1 & 0.89\% \\ \hline \multirow{2}{*}{6} & \multirow{2}{*}{Risk} & 7 & Optimal risk allocation in projects & 3 & 2.68\% \\  & & 6.25\% & Multi-project resource conflict risk prediction & 3 & 2.68\% \\  & & Prediction of financial contingency & 1 & 0.89\% \\ \hline \multirow{2}{*}{7} & \multirow{2}{*}{Contract} & 6 & Project dispute prediction and resolution & 3 & 2.68\% \\  & & 5.36\% & Prediction of project claim & 3 & 2.68\% \\ \hline \multirow{2}{*}{8} & \multirow{2}{*}{Schedule} & 6 & Project duration and time estimation & 4 & 3.57\% \\  & & 5.36\% & S-curve prediction, auxiliary schedule control & 2 & 1.79\% \\ \hline \multirow{2}{*}{9} & \multirow{2}{*}{Procurement} & 5/4.46\% & Contractor prequalification and selection & 5 & 4.46\% \\ \hline \multirow{2}{*}{10} & \multirow{2}{*}{Environment and sustainability} & 4 & Energy consumption evaluation & 3 & 2.68\% \\  & & 3.57\% & Environment assessment & 1 & 0.89\% \\ \hline \multirow{2}{*}{11} & \multirow{2}{*}{Other} & 9 & Model or system development & 7 & 6.25\% \\  & & 8.04\% & Trend forecast & 2 & 1.79\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: 11 application fields and 31 specific topics on ANN in CM. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Type** & **Features** & **Weakness** & **Applicable Field** \\ \hline BPNN & \begin{tabular}{l} Gradient descent method. \\ Nonlinear mapping function. \\ Self-learning and adaptive. \\ \end{tabular} & \begin{tabular}{l} Problem of slow convergence, \\ over-fitting, and local optima. \\ see Table 4. \\ \end{tabular} & \begin{tabular}{l} Applied to prediction and classification tasks in \\ CM: display \\ classification of patent screening, classification of \\ project decision. \\ \end{tabular} \\ \hline CNN & \begin{tabular}{l} Sparse connectivity and \\ weight sharing. Suitable for \\ high-dimensional data. \\ \end{tabular} & \
\begin{tabular}{l} Large amount of calculation, \\ and high requirements for \\ input data. \\ \end{tabular} &
\begin{tabular}{l} Applied to the image field in CM: safety risk \\ identification at construction site, sewer image \\ defect classification, equipment tracking \\ and monitoring. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}