## 4 Uniform Load Test Results and Discussion  
### Coupling Effect of Cold Bending and Uniform Load  
The coupling stress distribution produced by the coupling effect of cold bending and uniform load on cold-bent SGP laminated glass panels was significantly different to that on the flat glass. Hence, stress nephograms were used to analyze the coupling stress distribution and its changes on the cold-bent SGP laminated glass panels under a uniform load. The coupling stress distribution and its changes on SJ4 are given as a nephogram in Figure 7, which is similar in shape compared to those obtained from other specimens (not given in this paper). It can be inferred from Figure 7 that as the uniform load rose from 1 to 5 kPa, the coupling stress distribution changed from a cold-bending stress distribution to a quadrilateral stress distribution. At a uniform load of 1 kPa, the location of maximum coupling stress was consistent with that under cold bending, and the coupling stress near the panel center was enhanced. Meanwhile, the location of maximum coupling stress gradually moved towards the panel center as the uniform load rose. The area of tensile stress in the glass panel center was magnified, but the area of compressive stress in the panel edges shrank. When the uniform load was 5 kPa, the maximum coupling stress appeared at testing point S22, and the overall shape of the coupling stress nephogram turned to a spindle; in other words, the stress along the diagonal P\({}_{1}\)-P\({}_{4}\) was smaller at both ends and larger in the middle. The coupling stress values at testing points S22 and S30 for each specimen during the uniform load test are listed in Tables 3 and 4, respectively. Both tables exhibit a significant positive correlation between the coupling stress and the uniform load. The relationships between the coupling stress and uniform load at testing points S22 and S30 are depicted in more detail in Figure 8. Both points demonstrated a linear correlation between the coupling stress and the uniform load. The coupling stress at testing point S30 was greater than that at S22 when the uniform load was initially applied and the bearing capacity of the glass panel was controlled by the cold-bending curvature. However, the coupling stress at testing point S22 grew faster than S30 and even exceeded S30 at a certain uniform load. At this time point, the bearing capacity of the glass panel was controlled by the uniform load instead of the cold-bending curvature. With such a change in the control factor of bearing capacity, the corresponding uniform load increased with greater cold-bending curvature. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Specimens**} & \multicolumn{5}{c}{**Uniform Load**} \\ \cline{2-7}  & **0 kPa** & **1 kPa** & **2 kPa** & **3 kPa** & **4 kPa** & **5 kPa** \\ \hline SJ1 & 20.5 & 21.8 & 23.1 & 24.5 & 25.9 & 26.8 \\ SJ2 & 23.2 & 24.1 & 25.1 & 26.4 & 27.5 & 28.7 \\ SJ3 & 27.3 & 28.3 & 29.0 & 29.8 & 30.6 & 31.2 \\ SJ4 & 30.8 & 31.7 & 32.7 & 33.6 & 34.6 & 35.7 \\ SJ5 & 23.2 & 24.1 & 25.3 & 26.3 & 27.2 & 28.1 \\ SJ6 & 24.3 & 25.8 & 26.8 & 28.0 & 29.2 & 30.9 \\ SJ7 & 26.3 & 27.7 & 29.5 & 30.8 & 32.2 & 33.6 \\ SJ8 & 30.7 & 31.8 & 33.3 & 35.1 & 36.5 & 37.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The coupling stress of testing point S30 (MPa). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Specimens**} & \multicolumn{5}{c}{**Uniform Load**} \\ \cline{2-7}  & **0 kPa** & **1 kPa** & **2 kPa** & **3 kPa** & **4 kPa** & **5 kPa** \\ \hline SJ1 & 11.2 & 15.9 & 20.3 & 24.9 & 28.7 & 33.1 \\ SJ2 & 11.9 & 16.4 & 21.1 & 25.5 & 29.9 & 34.4 \\ SJ3 & 12.4 & 17.1 & 22.1 & 26.7 & 31.3 & 36.0 \\ SJ4 & 13.1 & 18.0 & 23.3 & 28.2 & 33.0 & 37.7 \\ SJ5 & 15.6 & 19.5 & 23.3 & 27.0 & 30.8 & 34.2 \\ SJ6 & 15.9 & 19.7 & 23.8 & 27.7 & 31.8 & 35.6 \\ SJ7 & 16.2 & 20.1 & 24.5 & 28.6 & 33.0 & 37.2 \\ SJ8 & 16.6 & 20.6 & 25.4 & 29.8 & 34.5 & 39.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The coupling stress of testing point S22 (MPa).