## 2 Experimental Method
### Experimental Program  
The vibration modal analysis instrument used in this modal experiment mainly consists of signal collector, IEPE signal input line, a current loop adapter, an acceleration sensor, a force hammer, a force transducer, and vibration analysis software, as shown in Figure 1. The vibration modal analysis instrument connects to the computer via USB 3.0, while the force hammer is linked to the force transducer to form the excitation system. In this test, seven HFGCWs were fabricated for testing, each comprising 600 \(\times\) 600 mm glass panels adhesively bonded to aluminum alloy frames using structural sealant. The panels with sealant joints of 6 mm thickness and 10 mm width are labeled clockwise as A, B, C, and D along the four sides, where blank boundary portions indicate areas of manually cut structural sealant to simulate debonding conditions, as shown in Figure 2. In the experiment, a sponge with sufficiently low stiffness was selected as the supporting material for the sample to simulate the load transfer characteristics of the actual cur  
Figure 1: Schematic diagram of the experimental setup: (**a**) exciting system; (**b**) vibration signal acquisition system. To simulate realistic HFGCW failure modes, artificial sealant debonding was introduced beneath the glass panels. Six distinct damage scenarios were designed, varying in both debonding locations and extents, to represent actual service conditions. These experimental conditions are illustrated in Figure 3, with detailed descriptions documented in Table 1.  
The test samples were positioned horizontally on a low-stiffness sponge support to simulate simplified elastic boundary conditions. This configuration was chosen to isolate the effects of sealant damage by minimizing external constraints, whereas real-world HFGCWs are vertically installed with rigid mechanical connections (e.g., pressure plates and bolts) that introduce additional stiffness. The horizontal orientation avoids gravity-induced pre-stress in the sealant, which could confound damage detection in small-scale laboratory tests. While the horizontal support simplifies modal analysis, it may alter curvature mode distributions compared to vertical installations. In upright curtain walls, gravity-induced \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Conditions** & **Condition 1** & **Condition 2** & **Condition 3** & **Condition 4** & **Condition 5** & **Condition 6** & **Condition 7** \\ \hline Damage scenario & Undamaged & Side A & Side B & Side C & Side D & Side A & Side A \\ description & Undamaged & debonding (33\%) & debonding (33\%) & debonding (33\%) & debonding (33\%) & debonding (66\%) & Debonding (100\%) \\ \hline Corresponding diagram & Figure 2(a) & Figure 2(b) & Figure 2(c) & Figure 2(d) & Figure 2(e) & Figure 2(f) & Figure 2(g) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Structural adhesive damage condition. Figure 3: Schematic diagram of experimental samples (**a**–**g**). Figure 2: Experimental samples. membrane stresses could stiffen the glass panel, potentially attenuating FCMD amplitudes at damaged edges. Future studies will validate this method in vertical configurations. The glass panel was uniformly divided into 36 small units with 49 measurement points to investigate the relationship between modal characteristics and structural sealant damage. Accurate modal displacement values were obtained sequentially by tapping each measurement point with a force hammer, which were subsequently processed using MATLAB R2024a software to derive corresponding curvature modal values. The sensor was placed at the 13 th measurement point, as shown in Figure 4. The acceleration sensor model used in this experiment was 1A102E-C190101432 with a sensitivity of 2.17 mV/N, the force hammer model was LC02-C190203129 with an axial sensitivity of 1.023 mV/(m/s2), and the sampling frequency was set to 2000 Hz.