# Punching Shear Stress in Post-Tensioned Transfer Plate of Multi-Story Buildings
## 6 Summary and Conclusions  
In this study, the validity of the separated model for the design of the post-tensioned transfer plate was analyzed. From the analysis of the two typical apartment plans, the following conclusions were drawn:  
1. The axial force of the separated model was found to be lower than that of the complete model at the corner columns and at columns located near core wall(s), when the load transferred through the core walls is not taken into account. Even considering the loads, the corner columns still showed lower axial force than the complete model.
2. In comparing punching shear stress at the critical section under the gravity load, shear stress calculated using the separated model was significantly higher compared to that of the complete model. The difference is attributed to the separated model and eccentric shear stress model not being able to consider the contribution of the shear wall(s) within the critical section on punching shear. Therefore, under current seismic design criteria, it is possible that the transfer plate could  
Figure 19: Maximum shear stress ratio vs. number of stories below (L-shape plan). (**a**) Corner and interior columns and (**b**) Exterior columns.  
be designed to be thicker than necessary for punching shear at columns with the shear wall(s) within the critical section using the separated model.
3. The difference in maximum shear stress subject to only lateral force using the modeling methods noted did not show obvious tendency, unlike the gravity load cases. However, punching shear stress calculated using the separated model at the interior column, where shear wall(s) is located within the critical section, showed lower values up to 10% than the complete model.
4. In comparing punching shear stress according to the number of stories below the transfer plate, the ratio of maximum shear stresses calculated by the two modeling methods changed as the number of stories below increased. However, there was no obvious tendency depending on the location of columns and the presence of shear wall(s) within the critical section. However, since the separated model is likely to lead to insufficient shear design as the number of stories below increases at the interior columns and at columns with no shear walls within the critical section, the separated analysis method is not recommended if the location of the transfer story is high.  
The significance of the current research is that this is the first study to investigate the behavior of the complete model with post-tensioning tendons in the transfer plate and/or that of the separate or complete model with post-tensioning tendons under lateral loads. Further research on various planar shapes, including Y-shape and behavior according to the number of upper stories, would also be needed to generalize the results of this study. In addition, analysis of a secondary effect that may occur in continuous members and the development of the strut-tie model for detailed design for the post-tensioned transfer plate is needed.  
Conceptualization, B.A., T.H.-K.K., S.-M.K. and J.K.Y.; Methodology, B.A., T.H.-K.K., S.-M.K. and J.K.Y.; Software, B.A. and J.K.Y.; Validation, B.A.; Investigation, B.A.; Funding acquisition, T.H.-K.K. and S.-M.K.; Supervision, T.H.-K.K.; Writing--original draft, B.A.; Writing--review & editing, T.H.-K.K. and S.-M.K.; All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MSIT) (Nos. 2015R1A5A1037548 and 2018R1A2B6007559).  
Valuable comments were provided by [PERSON] with Freyssinet Korea Co., Ltd. for analytical research.  
The authors declare that they have no conflict of interest.