# Numerical Simulation on Dynamic Behavior of Slab-Column Connections Subjected to Blast Loads
## 5 Conclusions  
The blast resistance of slab-column connection was numerically analyzed. The confinement effect of connection on the blast resistance was investigated through a comparison of the slab-interior column, slab-edge column, and slab-corner column. In addition, the effect of the drop panel on the blast resistance performance was investigated. The conclusions from this numerical study are as follows:  
1. Analysis results showed that the slab-interior column had a better performance than the slab-edge column and slab-corner column in terms of slab failure at critical section and column deformation. The confinement effect seems to be considered in the design of blast-resistant structures. However, the effect of the position of the column on the behavior of the slab such as slab deflection and support rotation under explosive load was not apparent. Further research is needed with the location of the explosive load and the dimensions of columns and slabs as variables.
2. The drop panel was observed to contribute to the improvement of the blast-resistance performance. For 4 kg and 12 kg of TNT, the drop panel reduced the maximum deflection of the slab at the critical section by approximately 86% and 17%, and the column deformation by approximately 2.9% and 4.8%, respectively.
3. Although significant concrete fracture occurred in the slab, the maximum stress of the reinforcing bar did not reach the tensile strength. This phenomenon occurs because the concrete is momentarily destroyed by the explosive energy and the energy is not sufficiently transmitted to the reinforcing bars. Further research is needed to ensure that the blast energy can be sufficiently transmitted to the rebar through the concrete.
4. For most design criteria, the support rotation has been considered as a major criterion for blast-resistant capacities. It is a very simple and good evaluation factor representing the critical behavior of the joint. However, in this study, considerable failure occurred in the slab member even though the support rotations at the critical section were satisfied with the criteria. Therefore, for a more accurate evaluation of blast resistance performance, various evaluation factors such as ductility ratio, reinforcing stress, and concrete fracture area can be considered along with the support rotation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Specimen** & \multicolumn{2}{c}{**Column Deformation (mm)**} \\  & **TNT 4 kg** & **TNT 12 kg** \\ \hline IC & 0.034 & 0.104 \\ IC-D & 0.033 & 0.099 \\ EC & 0.035 & 0.171 \\ CC & 0.038 & 12.91 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Maximum horizontal deformation of the column.  
**Author Contributions:** Conceptualization, K.M.L. and J.H.L.; data analysis and writing--original draft preparation, K.M.L.; writing--review and editing, K.M.L., T.H.H. and J.H.L.; supervision, T.H.H. and J.H.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by a grant (21 CTAP-C152069-03) from the Technology Advancement Research Program funded by the Ministry of Land, Infrastructure, and Transport of the Korean government.  
**Acknowledgments:** This paper is an extended version of the conference paper presented at the CECAR7 (2016). This research was supported by a grant (21 CTAP-C152069-03) from the Technology Advancement Research Program funded by the Ministry of Land, Infrastructure, and Transport of the Korean government.  
**Conflicts of Interest:** The authors declare no conflict of interest.