# Damage Assessment of Shear Wall Structures in an Earthquake-Blast Disaster Chain
## 4 Results and Discussions
### Displacement Time Histories  
The displacement-time-history curve was extracted from the top midpoint of the shear wall in the middle of the corner and the middle room. Figure 8 provides the time histories of the first, sixth, and twelfth-story displacement under the action of a Hector Mine earthquake-explosion disaster chain. During the earthquake, the top story will be displaced by approximately 1.00 cm. At the moment of the gas explosion, the explosion will dramatically alter the horizontal displacement of the shear wall structure, which will be about 4.00 cm. At this time, some structural members risk losing their bearing capacity and thus failing. Moreover, the increase in displacement will vary with the explosion location. When the explosion occurs on the first floor, the displacement of the first floor will increase instantly; on the other hand, the effects on the displacements of the sixth and twelfth floors will be relatively small. The reason for this phenomenon lies in the fact that the sixth and twelfth floors are far away from the explosion; in addition, after the initial shock wave from the explosion dissipated, the structure will enter into free vibration. The residual deformation caused by the explosion loads will be higher when the explosion occurs in the corner of the first story than when the explosion occurs in the middle of the first story. The other two earthquake excitations yielded similar results as the above. All the maximum displacements and the residual structural deformations are, respectively, summarized in Tables 7 and 8. The results show that the explosions would cause the structure to experience plastic deformation, which would significantly reduce the multi-hazard resistance of the structure and make future use of the structure problematic without extensive repairs. \begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Series**} & \multirow{2}{*}{**Case**} & \multicolumn{4}{c}{**Floor**} & & & & & & & & & & & \\ \cline{3-14}  & & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** & **12** \\ \hline \multirow{4}{*}{Series-II} & 4 & 14.4 &  
Figures 9 and 10 further show the peak displacement and the plastic deformation of each floor under an earthquake-blast disaster chain respectively. The earthquake-explosion disaster chain increased the overall displacement of the structure. It should be noted that deformations were much higher for the floor directly exposed to the explosion load than for the other floors. However, Figure 9 suggests that blasts have a stronger influence on structural performance compared to earthquakes. \begin{table}
\begin{tabular}{l l l l l l l l l l l l l l} \hline \hline \multirow{2}{*}{**Series**} & \multirow{2}{*}{**Case**} & \multicolumn{4}{c}{**Floor**} & & & & & & & & & & & & & & \\ \cline{3-14}  & & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** &  
Figure 11 presents the damage distribution of the shear wall structure exposed to the explosion in the corner room of the first floor after San Fernando earthquake. It can be seen that the damage caused by the earthquake is widely distributed in the shear wall structure. In contrast, the damage to the shear walls caused by the gas explosion is highly localized. According to the principle of energy conservation, the energy generated in a gas explosion disperses into the air and is absorbed by the shear walls. The absorbed energy causes large deformation and local damage of shear walls. The corresponding stress and strain field in the x direction are shown in Figures 12 and 13, respectively. It can be seen that the stresses and strains caused by the earthquake are much less than those caused by the earthquake-explosion disaster chain. This observation indicates that such a disaster chain cannot be ignored. Figure 10: Distribution of cumulative plastic deformation. Figure 9: Peak displacement of each floor.