# Damage Assessment of Shear Wall Structures in an Earthquake-Blast Disaster Chain
## 3 Numerical Simulation  
### FE Model of Shear Wall Structure  
This paper uses a 12-story building as an example case study. The building may be subjected to earthquake and explosion hazards during its service life. The shear wall structure was designed according to the Chinese Seismic Design Code [28; 29]. The fortification seismic intensity of the site is 7 degrees, equivalent to the design peak acceleration (PGA) of 0.10 g. The seismic design group is the first group, and the site soil category is II. The schematic of the prototype shear wall structure is shown in Figure 2. The structure was constructed with C40 concrete, which has a standard compressive strength of 40 MPa [30]. The software ANSYS was used to establish the FE model (Figure 3), which was then imported into the explicit dynamic FE analysis program LS-DYNA for numerical simulations [31]. Arbitrary-Lagrange-Euler (ALE) and fluid-structure interaction (FSI) algorithms were used to simulate the propagation of blast waves in the air and the interaction of the waves with the shear wall structure [24; 32]. The mesh sizes of the shear wall structure were determined by trial and error to optimally model damage modes and reflect the true dynamic responses of the shear wall structure. The mesh sizes of shear wall structure, air volume, and TNT were, respectively, 500, 500, and 100 mm. Note that in this study, the overall structural response was observed rather than the responses of the individual components. Thus, rebars were neglected to increase simplicity and computational efficiency. Furthermore, the seismic mass acting on the shear wall structure is 180 tons for each floor. The P-delta effect was taken into account in the FE model. The first three mode shapes of this shear wall structure are shown in Figure 4, with the first three periods being 0.54, 0.37, and 0.26 s, respectively. \begin{table}
\begin{tabular}{l l l} \hline
**Performance Level** & **Damage State** & **Drift** \\ \hline Fully operational & No damage & \textless{}0.2\% \\ Operational & Repairable & \textless{}0.5\% \\ Life safe & Irreparable & \textless{}1.5\% \\ Near collapse & Severe & \textless{}2.5\% \\ Collapse & & \textgreater{}2.5\% \\ \hline \end{tabular}
\end{table} 
Table 1: Performance levels, corresponding damage state, and drift limits. Considering that the HJC model cannot simulate the spalling and crushing of concrete, the keyword \(*MAT\_ADD\_EROSION\) was utilized to delete the excessively distorted  
Figure 4: The first three modes of the shear wall structure: (**a**) the first order; (**b**) the second order; and (**c**) the third order. Figure 3: FE model of the shear wall structure under earthquake–explosion disaster chains. Figure 2: Schematic diagram of the 12-story shear wall structure: (**a**) elevation; and (**b**) plan (Unit: m). structural elements. This function improves the chances of convergence and can accurately model structural failure and erosion. In this paper, the maximum erosion principle was set to 0.01 [33]. The parameters for modeling the concrete [21], TNT [33], and air [33] are listed in Tables 2-4, respectively. Throughout the duration of the earthquake, the shear wall structure, which has fixed end constraints in both the earthquake and explosion stages, is discretized by the solid164 element. The keyword \(*RIGIDWALL\_PLAANAR\) was used to create an infinite rigid ground. Regarding load application, two keywords \(*LOAD\_ BODY\_Z\) and \(*LOAD\_ BODY\_PARTS\) were used to apply gravity loads. Furthermore, the keywords \(*LOAD\_ BODY\_GENERALIED\_SET\_PARTS\) were used to apply the ground motions in the horizontal direction of the structure system. At the end of the earthquake, explosive loads were applied to the structure. The full restart method provided by LS-DYNA was used to reproduce the different loading steps. The air and TNT were simulated by the solid164 element. ALE is applied to simulate the propagation of blast waves in the air and their interaction with the shear wall structure.