# A Parametric Computational Study of RC Building Structures under Corner-Column Removal Situations
## 3 Results
### Vertical Reactions in the Adjacent Columns  
This section gives the vertical reaction forces in the adjacent column, P2, for each group of simulations (i.e., concrete tensile strength, flexural reinforcement ratio, number of floors, column removal time and superimposed load). The numerical reaction histories are depicted in Figure 9 from t = 0 s to t = 2 s. The results of columns P1, P4, P5 and P7 are reported in Appendix A, to which the reader is referred for further details. It is worth mentioning that from 0 s to 1 s the building supports gravity loads, while from 1 s to 2 s it undergoes the removal of ground floor column P3 and the subsequent free vibration phase.  
As can be seen by comparing Figure 9a,b,d, the peak vertical reaction force in P2 is not influenced by varying the concrete's mechanical properties, reinforcement ratio or column removal time, respectively. Each of these parameters influences the reaction force histories after the peak value. Higher concrete tensile strength reduces the formation of tensile damage in the structure and therefore extends the vibration of the building after the column removal (Figure 9a). A longer column removal time (Figure 9d) delays the peak value, but the results still reach the same peak and residual values. As expected, the application of higher superimposed loads and the higher number of floors modify the vertical reaction force in column P2, as can be seen in Figure 9c,e.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multicolumn{4}{c}{**Floor**} \\ \cline{2-5}  & \multicolumn{2}{c}{**1 st Floor**} & \multicolumn{2}{c}{**2 nd Floor**} \\ \cline{2-5}  & **Peak** & **Residual** & **Peak** & **Residual** \\ \hline M\_Ref & 0.61 & 0.21 & 1.99 & 1.36 \\ M\_fct2.5 & 0.73 & 0.28 & 1.85 & 1.16 \\ M\_fct3 & 0.71 & 0.27 & 1.76 & 1.11 \\ M\_\_\(\rho\)0.5 & 0.45 & 0.06 & 1.95 & 1.30 \\ M\_nf4 & 0.41 & 0.07 & 2.05 & 1.37 \\ M\_nf7 & 0.16 & 0.01 & 1.58 & 1.35 \\ M\_crt0.01 & 0.63 & 0.14 & 2.14 & 1.46 \\ M\_crt0.05 & 0.62 & 0.16 & 2.06 & 1.38 \\ M\_crt0.2 & 0.53 & 0.22 & 1.70 & 1.30 \\ M\_q9 & \(-\)0.74 & \(-\)0.46 & 1.57 & 1.05 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Residual and peak horizontal drift values obtained in each floor for each model. Units in mm.  
Figure 8: Numerical residual horizontal drift obtained by varying (**a**) concrete tensile strength, (**b**) flexural reinforcement ratio, (**c**) number of floors, (**d**) column removal time and (**e**) superimposed load.  
Figure 10 shows the axial force histories in the first-floor column P3 because it is a key element on the load redistribution of the load supported by the missing ground floor column, P3. As is clearly visible, the models behaved in two different ways: (i) from 0 s to 1 s and (ii) from 1 s to 2 s. In the first phase, all the models are subjected to compressive forces due to the application of the gravity loads,  
Figure 9: Numerical reaction in P2 obtained by varying (**a**) concrete tensile strength, (**b**) flexural reinforcement ratio, (**c**) number of floors, (**d**) column removal time and (**e**) superimposed load. Positive values indicate compression.  
while in the second phase the column is subjected to the effect of the sudden removal of the ground floor column, and column P3 suddenly loses almost all its axial force.  
Figure 10: Numerical axial force in P3 (first floor) obtained by varying (**a**) concrete tensile strength, (**b**) flexural reinforcement ratio, (**c**) number of floors, (**d**) column removal time and (**e**) superimposed load. Positive values indicate compression.