# Punching Shear Stress in Post-Tensioned Transfer Plate of Multi-Story Buildings
## 5 Analysis Results according to the Modeling Method  
### Column Axial Force  
In the separated model, the design of the punching shear of the post-tensioned transfer plate is performed based on axial force and moment of transfer column using the eccentric shear stress model. Given that the transfer plate is thick in comparison to the general slab, direct shear, rather than bending moment, typically governs [28]. In the separated model, load transferred through the core wall (same above and below the plate) is typically not considered. Since it is possible that axial force at the slab-column connection may be lower than that of the complete model, differences in column axial forces between the two modeling methods were compared for two plan shapes, Flat-shape and L-shape. The axial forces at the top of the transfer columns under gravity load are shown in Figure 9a,b. Figure 8: Punching shear stress along the critical section of slab-column connection. (**a**) Monitored points along critical section and (**b**) Assumed distribution of shear stress. For the Flat-shape plan, the difference between the axial forces of the separated model and the complete model ranged from 61% to 111%. At the corner columns, it was about 10% lower, and at the exterior columns, it was lower by more than 10%. Where columns were close to the core walls, the difference was more remarkable. Although Col. 2, 5 and 15 to 19 were exterior columns, there were few differences in axial force. However, at Col. 3, 4 and 10, which is relatively close to the core wall, differences noted were more than 18%. Meanwhile, in the L-shape plan, the axial force of the separated model was calculated as 51% to 113% of the complete model. At the corner columns, it was up to 17% lower than the complete model, and at exterior columns, it was up to 49% lower. As in the Flat-shape plan, significant differences were observed in columns near the core wall. The axial forces of Col. 10, 11 and 23 to 27 in the separated model differed by less than 5% from the complete model. Whereas, Col. 7 to 9, 12, 13, 15, 19 and 22 were 10% and up to 51% lower. A comparison of axial forces for the two plan shapes indicated that the current separated analysis model underestimates axial force on transfer columns near the core wall. Figure 9: Comparison of column axial force under gravity load according to the modeling method (without load transfer through core walls) (**a**) Flat-shape plan and (**b**) L-shape plan. Given the separated analysis, the method does not consider load transfer through the core wall, the total load transfer through the columns of the separated model and complete model were compared to analyze the effect (Table 4). The total load transferred through the column of the separated model was lower than that of the complete model by 4.6% in the Flat-shape plan and 5.5% in the L-shape plan. Using a modified separated model that considers load transferred through the core wall, the effect of a load of core wall was also analyzed. In Figure 10a,b, the difference in axial force using a modified separated model that considers load transferred through the core wall is depicted. The difference is significantly reduced in the modified separated model. In addition, the difference in total column load between the modified separated model and complete model was almost identical. Although the difference in columns located near the core wall decreased to less than 5%, the difference in corner columns was still roughly 7 to 8%. Therefore, the separated model, which does not consider load transfer through the core wall with respect to axial force, is not recommended.