## 2 STRC Shear Wall Failure Modes and Small Sample Database Establishment
### Feature Settings  
The accuracy and upper limit of ML models are directly influenced by the database and input features [35]. Currently, there is limited research on predicting the shear-bearing capacity of STRC shear walls using data-driven methods. In this paper, the input features are determined mainly by referring to the design codes for concrete structures, combined steel and concrete structures, and the existing literature on the seismic performance test studies of STRC shear walls in various countries, including JGJ 3-2010 [36] (Chinese code), CECS188:2005 [37] (Chinese code), JGJ138-2001 [38] (Chinese Code), ACI 318-19 [39] (American Code), EC-8 [40] (European Code), and the established literature [29; 30; 31; 32; 33; 34]. This paper establishes 18 input features from three aspects: geometric features (\(\lambda\), \(l_{w}\)/\(\theta_{w}\), \(A_{w}\)/\(A\), \(D\)/\(b_{w}\)), material properties (\(f_{a}\), \(f_{c}\), \(f_{y1}\), \(f_{y2}\), \(f_{y3}\), \(f_{y4}\)), and mechanical properties (\(n\), \(\rho_{cc,s}\), \(f_{y1}\)/\(f_{c}\), \(\rho_{w,s}\), \(f_{y2}\)/\(f_{c}\), \(\rho_{lmw}\), \(f_{y3}\)/\(f_{c}\), \(\rho_{h,c}\), \(f_{y4}\)/\(f_{c}\), \(\rho_{c,s}\), \(f_{u}\)/\(f_{c}\), \(\rho_{w,s}\), \(f_{u}\)/\(f_{c}\), \(\rho_{s,l}\)/\(f_{c}\)). To minimize the influence of dimensional features on the model's prediction accuracy, except for material property features, geometric and mechanical feature input features are all dimensionless features. Table 1 provides specific classifications and descriptions for each feature. The distribution histograms and curves of each input feature are shown in Figure 2a, where Min., Max., Mean, Median, and St. dev. represent the minimum value, maximum value, mean, median, and standard deviation, respectively. From Figure 2a, it can be seen that the distribution ranges of each feature are wide, and the database contains comprehensive information. The typical schematic diagram of STRC shear wall components in the database is shown in Figure 3, which demonstrates that the 18 input features can fully reflect the actual parameter characteristics of STRC shear walls. \begin{table}
\begin{tabular}{c c c l} \hline \hline
**Group** & **Symbol** & **Unit** & **Feature Description** \\ \hline \multirow{6}{*}{Geometric characteristics} & \(\lambda\) & (-) & Shear–span ratios. \\  & \(l_{w}\)/\(b_{w}\) & (-) & Wall length and thickness ratios. \\  & \(A_{w}\)/\(A\) & (-) & Area share of webs. \\  & \(D\)/\(b_{w}\) & (-) & Steel tubular diameter to wall thickness ratio. \\ \hline \multirow{6}{*}{Material properties} & \(f_{c}\) & MPa & Yield stress of steel tubular. \\  & \(f_{a}\) & MPa & Concrete compressive strength. \\ \cline{1-1}  & \(f_{y1}\) & MPa & Yield stress of vertical bars in boundary element. \\ \cline{1-1}  & \(f_{y2}\) & MPa & Yield stress of vertical bars in the web. \\ \cline{1-1}  & \(f_{y3}\) & MPa & Yield stress of horizontal bars in the web. \\ \cline{1-1}  & \(f_{y4}\) & MPa & Yield stress of horizontal bars in boundary element. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification and definition of input features for STRC shear walls.