# Performance Evaluation of Rigid Braced Indirect Suspended Ceiling with Steel Panels
## 3 Test results
### Analysis of the Damage for the Ceiling with the Brace  
Based on the experimental results, the damage that was caused to the ceiling grid members and the panels were analyzed. It was confirmed that the factors that caused the dislodged panel and hanging state, which is a damage state that can occur because of the anti-falling clip, and the factor that caused the panel falling state appeared in order. This indicates that the damage state in the previous stage has a direct effect on the damage state afterwards. The first factor in the panel dropout of the USD that was conducted in a previous study was the occurrence of the impact loads at the ends because of the short clearance. In this case, the grid members forming the ceiling surface are simultaneously moved until the impact load is generated at the ends; however, due to the uneven impact load, the panels at the ends are first failures, and then the panels at the center subsequently fail. This is because it is difficult to construct the same distance between the ceiling grid and molding. In Section 3.3, the most significant damage that was caused by the brace-applied ceiling system was identified as the relative displacement of the part with and without the brace. The grid member furthest from the brace generates an impact load afterwards as the acceleration level increases; however, it can be observed that the panel fails before the impact load occurs. The order of the cause of damage, which is presented below, was analyzed based on the experimental results of SDB-2. This study confirmed that the damage occurred a similar order to SDB-3. The main types of damage that affect the panels and the ceiling grid members in the brace-applied ceiling system are in the following order. 1. Dislodging of the panel and hanging of the end panel because of the relative displacement of the installed brace parts and the uninstalled parts. When the brace is installed on the ceiling system, relative displacement occurs between the rigidity of the installed brace part and the part member where it is not installed, which causes the panel that is installed at the end to escape the molding and it is lost. In the case of the T-bar system, the in-plane diaphragm does not function owing to the lack of lateral stiffness in the grid members that form the ceiling. For this reason, a large deformation occurred in the center of the specimen, as shown in Figure 16. However, in the case of SDB-2, because the width of the molding is so large that it does not cause the panel to fall out, the end panel did not come off. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Maximum disp. Of SDB-2**} & \multicolumn{4}{c}{**Maximum disp. Of SDB-3**} \\ \cline{2-9}  & **Frame** & **Ceiling** & **Relative** & **Remark** & **Frame** & **Ceiling** & **Relative** & **Impact** \\  & **(mm)** & **(mm)** & **(mm)** & **Remark** & **(mm)** & **(mm)** & **(mm)** & **Load** \\ \hline Test 1 & & & & & & & & & \\ (0.432 g) & 33.7 & 23.0 & 4.4 & - & 45.9 & 46.0 & 2.3 & - \\ Test 2 & & & & & & & & \\ (0.864 g) & 74.6 & 51.7 & 22.4 & - & 79.4 & 80.2 & 5.1 & - \\ Test 3 & 76.3 & 63.4 & 36.0 & Panel & 92.6 & 93.7 & 4.3 & - \\ (1.08 g) & 76.3 & 63.4 & 36.0 & \begin{tabular}{c} Impact \\ occurred \\ \end{tabular} & 92.6 & 93.7 & 4.3 & - \\ Test 4 & & & & & & & & \\ (1.296 g) & 97.6 & 82.1 & 41.3 & \begin{tabular}{c} Impact \\ occurred \\ \end{tabular} & 116.4 & 117.0 & 5.8 & - \\ Test 5 & & & & & & & \\ (1.512 g) & 153.3 & 92.3 & 56.1 & - & 137.0 & 136.3 & 7.4 & - \\ Test 6 & & & & & & & \\ (1.728 g) & 104.1 & 57.2 & - & 156.6 & 156.3 & 9.8 & \
\begin{tabular}{c} Panel \\ failure \\ \end{tabular} \\ Test 7 & & & & & & & & & \\ (1.944 g) & 194.1 & 125.1 & 59.7 & - & 176.3 & 175.8 & 13.4 &
\begin{tabular}{c} Impact \\ occurred \\ \end{tabular} \\ Test 8 & & & & & & & & \\ (2.16 g) & 247.9 & 138.3 & 59.5 & - & 199.0 & 195.2 & 19.9 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Maximum frame displacement, ceiling displacement, and the relative displacement.