## 3 Seismic Performance of the Frame with CFST Dampers
### Hysteretic Loops Analysis of Three Components GJ-1,Gj-2 and GJ-3  
The hysteretic response is a concentrated reflection of the seismic performance of reinforced concrete members. The hysteretic loops of the three models GJ-1, GJ-2, and GJ-3 are shown in Figure 9, and \(\Delta\) is the horizontal displacement at the loading point. All the hysteresis loops are limited by two curves having one inflection point [21] and are characterized by cyclic softening phenomena [22]. The limiting state criterion in the simulation  
Figure 8: Failure process and failure form of GJ-3. (**a**) The first concrete plastic strain element at the left column foot; (**b**) crack development at the bottom of the wall and columns; (**c**) the first right oblique crack of the shear wall; (**d**) the first left oblique crack of the shear wall; (**e**) the second right oblique crack of the shear wall; (**f**) penetrated cracks appear in the frame column; (**g**) yield of main stressed bars; (**h**) crack penetrated the wall and column; (**i**) the shear wall has cracks developing to the upper right; (**j**) the corresponding cloud chart of the reinforcement when the cracks occur at the upper right; (**k**) the lower part of the wall is bulging; (**l**) cloud chart of stiffness degradation of wall and columns; (**m**) cloud chart of compression failure of GJ-3; (**n**) cloud chart of tension failure of GJ-3. test records the time when the bearing capacity of the specimen drops to 85% of the peak bearing capacity (unless otherwise specified, the criterion is followed in the following). From Figure 9a, it can be seen that the hysteretic loop of GJ-1 with CFST dampers has complete ascending and descending segments, where the descending segment is very stable and the middle of the curve is slightly pinched. Under the action of horizontal loading, the hysteretic loop area of the component is large, indicating that the component has excellent ductility. The slope of the hysteretic loop of concrete before cracking is basically unchanged. At this time, the residual strain is small, and the hysteretic loop is generally in the shape of a sharp shuttle. When the applied displacement reaches 2.483 mm, the component cracks with a cracking load of 492.406 kN. After cracking, the slope of the curve becomes smaller. When the applied displacement reaches about 17.01 mm, the load-carrying capacity of the component reaches the peak value of 1669.477 kN, and then the slope of the hysteretic loop decreases significantly. With the increase in the applied displacement, the slope decreases more rapidly. Through analysis, it is known that the concrete damage of the frame columns at both ends becomes more serious with the increase in the applied displacement after reaching the ultimate load, which is called the stiffness degradation of  
Figure 9: Hysteretic loops. (**a**) GJ-1; (**b**) GJ-2; (**c**) GJ-3. the component under repeated load. After the peak load is reached, the load-carrying capacity of the second load decreases by less than 2% when the same level load is applied. In general, it has superior energy dissipation capacity and excellent seismic performance. However, the residual deformation of the whole frame gradually increases in the late loading period, indicating that the structure has large damage. From Figure 9b, the main characteristics of the hysteretic loop of GJ-2 are as follows. It has complete ascending and descending segments, where the descending segment is relatively stable, the middle of the curve is pinched seriously at the initial stage of loading, and the hysteretic loop becomes full after the loading displacement reaches 25 mm at the later stage. By comparing the GJ-1 hysteretic loop, it can be seen that the hysteretic loops of the two components are generally similar, but the main differences are as follows. The cracking load of GJ-2 is higher than that of GJ-1. When the applied displacement reaches 1.358 mm, the cracking load is 657.354 kN. The peak load of GJ-2 is also higher than that of GJ-1.