## 3 Experimental Program
### Test Setup  
In this research, cyclic loading involving eccentric lateral forces was applied to simulate the torsional effects of seismic loads on structures. A specialized jig was used to apply axial and lateral forces at specific points on the test specimens, and the experimental setup is illustrated in Figure 8. For clarity, the front of the specimen was designated as Side 1, while the other sides were labeled Sides 2, 3, and 4 in a clockwise direction. Lateral forces were introduced using a hydraulic actuator with a capacity of up to 1000 kN, controlled through displacement. The hydraulic actuator was positioned between the reaction wall and the specimen, connected to the top of the column through a jig. This jig, situated at both ends of the column's top and linked with steel rods, ensured a uniform introduction of loads in two directions during cyclic loading. The experiment involved varying the eccentricity of the applied lateral force, including scenarios with no eccentricity and eccentricities of 65 mm and 130 mm. This variation aimed to scrutinize the dynamic behavior of RSL-retrofitted reinforced concrete columns. The loading protocol adhered to the guidelines of 4C1 374 [23], which defines the standards for structural experiments on moment-frame structures. The following loading protocol was adopted for assessing structural performance through cyclic loading:  
1. The initial drift ratio should fall within the range of linear elastic behavior.
2. Subsequent drift ratios should not exceed 0.25% and then should not surpass 0.5%.
3. The steps between subsequent drift ratios should be judiciously chosen, ensuring the experiment progresses up to a drift ratio of 3.5%.
4. Each drift ratio should be repeated for three cycles of cyclic loading.  
Accordingly, in this study, cyclic load testing was conducted for each drift ratio over three cycles. The initial drift ratio was set to 0.2%, with a subsequent ratio of 0.25%, and the experiment was planned to conclude when the load on the specimen was reduced to less than 80% of the maximum load after reaching the peak. The drift ratio is defined as the lateral displacement of a column at the point of load application (1800 mm from the bottom) divided by the column's height. To simulate real seismic loads acting on columns, constant axial forces were applied using a hydraulic jack. Columns with an axial load ratio exceeding 0.3 are less likely to exhibit nonlinear behavior and are more prone to brittle failure, while those with a ratio greater than 0.6 have almost no ductility due to excessive axial load [24; 25]. Therefore, an axial load ratio of 0.17 was set to observe the dynamic behavior of the specimens. The axial load ratio was calculated as shown in Equation (2). For the test of the specimens in this study, a constant axial load of 255 kN, corresponding to an axial load ratio of 0.17, was applied to the top of the columns using a hydraulic jack.  
\[\
u=P/A_{g}f^{r}_{c} \tag{2}\]  
Here, \(\
u\) is the axial load ratio, \(P\) is the axial force introduced into the reinforced concrete columns, and \(A_{g}\) refers to the cross-sectional dimensions of the reinforced concrete columns.