## 2 The Split Column Technology  
The split columns are several independent unit columns divided using partition plates, and each unit column is independently reinforced. The structural diagram of split columns is shown in Figure 1. When cast-in-place reinforced concrete columns are used, partition plates are generally set between unit columns, and there is a bond between the unit column and the partition plates. In terms of assembled reinforced concrete columns, partition plates are not necessary, and frictional contact between unit columns is produced directly. Experimental and theoretical studies [27; 28; 29; 30; 31] have shown that when the split column technology is used in the ground buildings, although the flexural bearing capacity of the column is reduced, the shear bearing capacity remains basically unchanged, and the deformation capacity and ductility are significantly improved.  
Taking the cast-in-place reinforced concrete column as an example, the loading process can be divided into three stages according to the degree of friction effect between the partition plate and the unit column. The strain distribution law of concrete in the cross section of the split column at different stress stages is shown in Figure 2, where \(w_{1}\) is the width of the unit column and \(w_{2}\) is the width of the partition plate. When the horizontal load on the split column is small, there is an effective bond between the partition plate and the concrete. The unit column on both sides of the partition plate is guaranteed to deform in a coordinated manner, and the strain distribution of the cross-section is similar to that of the monolithic column at that time. Furthermore, when the horizontal load increases to a certain degree, the bond between the partition plate and the concrete is gradually broken. The friction between the two restrains the deformation of the concrete on both sides of the partition plate, resulting in a smaller strain at the inner edge of the unit column. When the horizontal load continues to increase, the bond between the partition plate and the concrete is completely destroyed, and the friction between them is completely eliminated. The partition plate will no longer restrain the deformation of the concrete on both sides. Therefore, each unit column works independently, and the neutral axes of each unit columns move to their section center, respectively.  
Figure 1: Structural diagram of split columns.  
Figure 2: The strain distribution of the split column.  
According to the distribution characteristics of strain within the cross section of the split column, the force of the split column is simplified as shown in Figure 3. Assuming that the height of the column is \(H\), forces causing the bending deformation of the unit column are the horizontal load \(P\) and the shear force \(Q_{f}\), where \(Q_{f}\) is the distributed shear force along the column height (i.e., the interaction friction between unit column and partition plate). When the bond between the unit column and the partition plate is intact or with large friction, the \(Q_{f}\) would be larger, and the loading condition of the column is closer to the monolithic one. When there is no friction between the unit column and the partition plate, \(Q_{f}\) is 0 with the unit columns working independently.